[PATCH v5 1/2] Add documentation for SPI to CAN driver

[Stefano Babic]

Signed-off-by: Stefano Babic <***@denx.de>

---

Changes in v5:
- drop Patch 2/3, already applied.

Changes in v4:
- added GET_CFG message to query bit timing to the remote controller.

Changes in v3:
- format documentation, check for lines > 80 chars (O. Hartkopp)
- patch 2/3 already aqpplied to can-next, removed from patchset

Changes in v2: None

Documentation/networking/spi_can.txt | 774 +++++++++++++++++++++++++++++++++++
1 file changed, 774 insertions(+)
create mode 100644 Documentation/networking/spi_can.txt

diff --git a/Documentation/networking/spi_can.txt b/Documentation/networking/spi_can.txt
new file mode 100644
index 0000000..82f33e7
--- /dev/null
+++ b/Documentation/networking/spi_can.txt
@@ -0,0 +1,774 @@
+The spi_can driver is intended to provide a general protocol
+to support CAN interface that are not directly connected or
+part of the main controller, but they are available on a
+separate controller, such as a low cost/low power microcontroller
+(for example, very simple 16 bit controllers providing multiple CAN
+ busses).
+
+This document is intended to describe the internal protocol
+on the SPI interface between the linux system (main controller)
+and the remote CAN controller(s).
+
+1. Overview
+----------------------
+
+The CAN controller processors supports up to N Can Busses. The Main Controller
+driver should be able to manage all CAN busses. It is then
+responsibility of the SW Main Application to decide which controllers
+(which CAN channels) should be opened and used.
+
+There is the requirement to configure the CAN controller, sending some
+parameters or commands not strictly related to the CAN interfaces. For example,
+it is required that the application sends periodically a message to the CAN
+controller, that has the responsibility to supervise the Main Controller. If the
+message is not received in time, the CAN controller must perform a reset of the
+Main Controller controller (Watchdog message).
+Another known use case is to configure the wake-up mechanism, that is
+under which circumstances the CAN controller must awake the Main Controller
+(ignition, opened door,...). The protocol foresees an additional channel (CFG)
+used to exchange data between the application layer and the CAN controller.
+
+The document sets the rules to exchange messages between the Main Controller and
+the CAN controller and allows to extend the functionalities with new messages
+(see Chapter 5) in the future.
+
+2. Interface to upper layer
+------------------------------
+
+The driver must provide a socket CAN interface. In this way, the
+application is able to communicate with CAN via usual sockets.
+A detailed description can be found in the kernel documentation
+(Documentation/networking/can.txt).
+
+On the application level there will be network interfaces, and
+they can be set up with Linux tools such as "ifconfig" and "ip".
+
+For the CAN controller configuration it is proposed to add a further network
+device ("cfg") to have a consistent interface. In this way, the
+driver must not expone itself in a different way to the application SW.
+Configuration packets are simply forward to the CAN controller exactly as it is
+done for the other channels. The application fills data for the cfg
+interface and the Main Controller driver does not need to look inside.
+Configuration data are treated by the CAN driver exactly as all other CAN
+packets.
+Only the SW application and CAN controller-SW are aware of it.
+
+The driver must be able to mux/demux packets from the socket can interface.
+Indeed, there is only one SPI interface to to communicate with the CAN
+controller, and the driver instantiates automatically multiple network
+interfaces.
+On the downstream direction, the driver must take packets from all interfaces
+(hcan0,..hcan4), set up a frame header (message type,
+channel number, etc.) and send it to CAN controller via the SPI interface.
+
+
+ hcan0 hcan1 hcan2 hcan3 hcan4 cfg
+ | | | | | |
+ | | | | | |
+ ,__|_____|____|_______|_______|____|_
+ | |
+ | |
+ | SOCKET CAN (Kernel) |
+ | |
+ L________________,.__________________|
+ ,!!;
+ ,!!;
+ `!!.
+ ;!!.
+ ,'''''''''''''''''''''''''''''''''''`.
+ | +------------------------------. |
+ | | Channel Mux/Demux | |
+ | L______________________________| |
+ | |
+ | +------------------------------. |
+ | | Can to SPI controller | |
+ | L______________________________| |
+ |..................................../
+
+
+On the upstream direction, the driver must be able to demux the received
+frames and forward them to the related network interface.
+
+The cfg is a special CAN interface used only to set up the
+CAN controller behavior and does not map to a physical CAN channel, as the other
+CAN interfaces do. The scope of such interface is to provide a way to
+exchange messages with the CAN controller processor that are not strictly
+related to the CAN bus. As example for such messages, a watchdog message must
+be sent regularly by the Main Controller to the CAN controller, and it is sent
+as CAN data to channel that matches the imxhcs12. The driver is not aware of
+these messages, as they are seen as normal data messages for a CAN channel.
+This guarantees that it is possible in future to extend the list of these
+configuration messages without changing the driver. The partners that must know
+their format are the application software in user space and the CAN controller
+Software.
+
+3. Interface to HW
+---------------------------
+
+The CAN controller is connected to the Main Controller via the SPI interface.
+
+3.1 SPI Hardware Connection
+---------------------------
+
+ - Main Controller is always the Master and the CAN controller in slave mode.
+
+ - Maximal frequency:
+ The limit is set by the CAN controller, because it must serve an interrupt
+ request before the next two bytes are sent.
+
+ The CAN controller has two operational modes: "User Mode" and
+ "Supervisor / Maintenance" Mode. The last one is used to update
+ the software on the CAN controller.
+ In Supervisor Mode, the CAN controller runs with little support for its
+ peripherals. The maximum SPI frequency is limited to 1 Mhz.
+ The driver must support two different operational frequencies,
+ and must be able to switch between them.
+ This is done using the CFG_MSG_SET for the CFG channel, see details in chapter 6.
+
+ - bit x words : it was tested with 32 bits. This means that the Main Controller
+ deactive the chip select automatically (without intervention by Software)
+ each 4 bytes. No interrupts are generated on the Main Controller because they
+ are ruled by the internal FIFO.
+
+ - GPIO(s):
+ IRQ GPIO: set active by CAN controller when it has something to send
+ it raises an interrupt on Main Controller side.
+
+To transfer data, some frame header will be included. If a field contains more
+as one byte, a big endian convention is used (MSB is transmitted first).
+
+The SPI interface is full duplex. This means, both Main Controller and CAN
+controller are transmitting data at the same time. It is possible to transfer
+CAN messages to and from the CAN controller in the same SPI transfer.
+
+4. SPI Protocol between Main Controller and CAN controller
+----------------------------------------------------------
+
+The format of the frames exchanged between Main Controller and CAN controller
+is:
+
+
+ ,'''''''','''''''''''''''','''''''''''''''''''''''','''''''''''''|
+ |MSG ID | Length(16 bit)| DATA | CHECKSUM |
+ L________|________________|________________________|_____________|
+
+The checksum is thought to be used in the development phase to check
+for implementation's error. It should be possible to disable it after
+the development is finished. The SPI interface ensures that data are
+transfered without modification between the two processors.
+
+The checksum is computed as 16 bit 2's complement of the sum (module 16)
+of all bytes in the message, excluded the checksum itself.
+On the receive side, it is enough to sum all bytes including the checksum
+to verify if the message was received correctly (the sum must be zero).
+
+The MSG-ID (1 byte) identifies the type of exchange data. For basic exchange
+of frames, the following messages are used:
+
+ SEND_DATA_MSG
+ STATUS_MSG
+ SYNC_MSG
+ CFG_MSG_SET
+ CFG_MSG_GET
+ REQ_DATA_MSG
+
+The SEND_DATA_MSG is used when one of the two processors needs to send a CAN
+message.
+
+The STATUS_MSG is used to inform the partner about the number of bytes ready
+to be transfered. This is used by the Main Controller when it has several
+messages to send, and it needs a longer frame as usual to sen all CAN messages
+back.
+
+The SYNC_MSG is used to start up the communication and in case an error is
+detected. It is the first message that the Main Controller will send to the
+CAN controller.
+Because the Main Controller will always send the MSG ID as first byte in the
+frame, the SYNC_MSG is used to signalize the start of a frame to the CAN
+controller.
+The SYNC_MSG is used also to initialize or reinitialize the time on the
+CAN controller. It is not required to the CAN controller to have an absolute
+time synchronized to the Main Controller. It is enough to have a relative time,
+and the Main Controller computes the absolute time to add it as timestamp to
+the received packets.
+
+The CFG_MSG_SET is sent to configure the CAN channel for bitrate and timing.
+The driver on the Main Controller does not need to parse the parameters and it
+forwards them to the corresponding CAN controller's CAN interface.
+
+The CFG_MSG_GET is sent at the start up to query the CAN controller about its
+internal timing, making them available to the netlink interface. CAN drivers
+have usually fest values for can_bittiming_const. In case of a remote
+CAN controller driven via SPI, the Main Controller cannot know the timing
+and must ask them to the CAN controller before instantiating a CAN device.
+For this reason, the message is sent only once in the probe() entry point.
+
+The REQ_DATA is sent only by the Main Controller when the Main Controller
+signals it has packets to be transfered, but the Main Controller has nothing
+to sent. Its scope is mainly to signalize to the Main Controller the Start of
+the Frame and to pass in the LENGTH field the number of bytes of the frame
+itself.
+After receiving the REQ_DATA message, the CAN controller knows how many bytes
+is allowed to send without fragmenting frames on the Main Controller's side.
+
+4.1 Start of the comunication
+-----------------------------
+
+The Main Controller does not poll continuosly the CAN controller.
+If it has nothing to send, it waits to get an interrupt on the GPIO-line.
+
+If the CAN controller has packets to be sent, it sets the GPIO-IRQ,
+and this raises an interrupt on Main Controller side.
+
+The CAN controller can sends enough messages as they can fit inside
+the SPI transfer. The number of bytes (=SPI clock cycles)
+to be transfered is set by the Main Controller inside the Status Message.
+
+ | |
+ |GPIO(IRQ for Main Controller) |
+ |<------------------------------'
+ | |
+ | First SPI Transfer started |
+ | SPI:REQ_DATA |
+ |------------------------------>|
+ | SPI:Send Data |
+ |<------------------------------|
+ | SPI:Send Data |
+ |<------------------------------|
+ | SPI: Status |
+ |<------------------------------|
+ | |
+ | New SPI Transfer started |
+ | SPI:Send Data |
+ |------------------------------>|
+ | SPI:Send Data |
+ |<------------------------------|
+ | |
+ | |
+ | |
+ Example of SPI transfer.
+
+The CAN controller sets the GPIO-IRQ, and this raises an interrupt on the
+Main Controller.
+The protocol uses several Message-IDs to identify what is really exchanged.
+
+From the Main Controller point of view, a SPI Transfer is initiated when the
+first byte is written into the internal FIFO and it is finished when the all
+bytes are transmitted. The protocol relies on the positional place of the
+bytes, that means there is no need to wait for a start-frame byte.
+
+On the receive side, due to CAN controller limitations, the Main Controller
+must drop the first 4 bytes received from the CAN controller, as they have
+no meaning.
+It must be ensured by the CAN controller software that the first valid byte
+is the fifth in the SPI transfer.
+
+The Main Controller has no knowledge at the beginning how many messages the
+CAN controller will send and it starts with a 32-bytes transfer because this
+matches the internal FIFO and raises only one interrupt.
+If the CAN controller has communicated with the status message
+the number of bytes it needs for the next SPI frame, the Main Controller will
+start a SPI transfer for a number of bytes equal or greater
+as the received value.
+Sending imediately a new SPI transfer should minimize the delay to transfer
+CAN messages into the socket CAN layer, and setting the transfer to
+a multiple of 32 is a best-effort for the CPU load on the Main Controller side,
+because it matches the internal FIFO size (tested on i.MX35). However, there is
+no restrictions about the number of bytes to be transfered, and it is duty of
+the Main Controller driver to find the most valuable length to be used.
+
+A SPI transfer is *NOT* delimited by changes of the chip select signal. Indeed,
+the chip select is ruled internally by the bits x word setup, and it is made
+suitable for both CAN controller and Main Controller. Bits x words must be a
+multiple of 2, because the CAN controller gets an interrupt each 2 bytes.
+
+
+5. SPI Communication scenarios
+-------------------------------
+
+5.1 The CAN controller wants to send data, no data from Main Controller
+-----------------------------------------------------------------------
+
+The CAN controller sets the GPIO to raise an interrupt on the Main Controller.
+The CAN controller sets always the GPIO if it has something to sent, and it is
+duty of the Main Controller to disable and enable the interrupt source depending
+on the status of the transmission.
+
+After getting the interrupt, the Main Controller (that has no knowledge about
+the amount of data to be transfered from the CAN controller), will start a SPI
+transfer for a total of 32 bytes (default), sending a REQ_DATA message.
+
+This is the best-effort way for the Main Controller, as it will transfer so many
+bytes as the internal FIFO can, and only one ISR is raised to terminate the
+transfer.
+Taking into account that the header requires 3 bytes (MSG-ID + length) and the
+checksum further two bytes, there are still 27 bytes available for the CAN
+messages.
+This is always enough to send at least one CAN message.
+
+The CAN controller answers with the SEND_DATA_MSG. The Main Controller knows
+that there is no message from the Main Controller, because the MSG-ID is not
+set to SEND_DATA, and acquires the number of bytes to be transfered from the
+length field.
+The CAN controller packs so many CAN messages inside the SEND_DATA_MSG
+(usually 1 or 2), delimiting the packet with the checksum as described before.
+
+
+ Main Controller ,''''''''''''''''''''''''''''''''''''''''''''''''''|
+ (MOSI) '''| REQ_DATA |
+ |__________________________________________________|
+
+
+
+ CAN Contr.,'''''''''''''''''''''',''''''''''''''''''''''''''''|
+ (MISO) |Do not care (4 bytes) | Send DATA MSG |
+ | | |
+ '`''''''''''''''''''''''`''''''''''''''''''''''''''''
+ 32 bytes long transfer
+ '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+There are two options at this point:
+
+5.2 The CAN controller has sent all CAN messages.
+-------------------------------------------------
+
+In this case, the CAN controller deasserts the GPIO line to avoid further
+interrupts for the Main Controller.
+
+5.3 The CAN controller has more data to be sent.
+------------------------------------------------
+
+It can send a STATUS_MSG message, if it fits into the current transfer.
+There is no rule about when sending this message. The main constraint for
+the CAN controller is that the packets must not be fragmented, that is, there is
+still enough place inside the current frame to send the STATUS_MSG.
+The CAN controller can decide also to send the Status Message before the
+SEND_DATA_MSG.
+Anyway, because the length of a STATUS_MSG is fixed (5 bytes), it is sure that
+the CAN controller is always able to send a SEND_DATA_MSG and a STATUS_MSG
+inside a standard (=32 bytes) SPI transfer.
+
+
+ Main Controller ,''''''''''''''''''''''''''''''''''''''''''''''''''|
+ (MOSI) '''| REQ_DATA |
+ |__________________________________________________|
+
+
+CAN Controller ,'''''''''''''''''''''''''''''',''''''''''''''|
+ | SEND DATA | STATUS |
+ | | |
+ `''''''''''''''''''''''''''''''`'''''''''''''
+
+
+After receiving the STATUS_MSG, the Main Controller is aware of the number of
+bytes the S12 wants to send. It starts without waiting for the GPIO-ISR
+and sends (if it has no messages for the CAN controller) a new REQ_DATA
+with the length of the SPI transfer, followed by dummies 0x00.
+The length could be changed by the Main Controller, but it must not be smaller
+as the value required by the Main Controller in the STATUS_MSG.
+
+ Main Controller ,''''''''''''''''''''''''''''''''''''''''''''''''''''''|
+ (MOSI) '''| REQ_DATA |
+ |______________________________________________________|
+
+
+ ,'''''''''''''''''''''''''''' ,''''''''''''''''''''''''''''',
+ | SEND DATA | SEND DATA |
+ | | |
+ `''''''''''''''''''''''''''' `'''''''''''''''''''''''''''''
+
+The CAN controller has now enough SPI clock cycles to send all data
+to the Main Controller. After sending all data, it will fill also any
+remaining bytes until the end of transfer with dummy bytes.
+
+In case there is no place for the STATUS_MSG and because it is not allowed
+to fragment packets, the CAN controller must maintain assert the GPIO-IRQ line
+and wait until the Main Controller will start a new transfer again.
+
+5.4 Both CAN controller and Main Controller has data to be sent
+----------------------------------------------------------------
+
+The CAN controller asserts the GPIO line to raise an interrupt. The interrupt
+can be served or not, depending if the Main Controller has already recognized
+that it must send data. The GPIO is used from the Main Controller as
+level-interrupt, and the Main Controller is able to activate it when no transfer
+is running, and to deactivate it when it already knows there are messages
+to be exchanged.
+
+The scenario is quite the same as previously:
+
+
+
+ ,'''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
+Main | SEND DATA | ...........
+ | |
+ `''''''''''''''''''''''''''''''`''''''''''''''''''''''''''
+
+ ,'''''''''''''''''''''''''''',
+CAN Controller | SEND DATA |
+ | |
+ `'''''''''''''''''''''''''''
+
+The Main Controller starts with the SEND_DATA_MSG. If it has a lot of CAN
+messages to be sent, it sets accordingly the length field and it packs all CAN
+messages inside the same single SEND_DATA_MSG.
+
+The CAN Controller, that has something to send, will answer with the
+SEND_DATA_MSG, too.
+Because it has already received the length of the incoming message, it is
+aware about how many bytes are transfered and can act as in 5.3 if it has more
+messages to send.
+
+5.5 The CAN controller gets new data during a transfer
+------------------------------------------------------
+
+In this case, there are the following options:
+
+- the new messages can be fit inside the actual transfer.
+Then the CAN controller will append a new SEND_DATA_MSG to the end of the
+data that it is currently sending on the SPI line.
+
+ Main ,''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''|
+ (MOSI) '''| REQ_DATA |
+ |___________________________________________________________________|
+
+
+ ,'''''''''''''''''''''''''''' ,''''''''''''''''''''''''''''',
+CAN Controller | SEND DATA | SEND DATA |
+ | | |
+ `''''''''''''''''''''''''''' `'''''''''''''''''''''''''''''
+ ^--at this point, new can message(s) is(are) received
+
+- the new messages cannot be fit inside the actual SPI transfer
+but there is place for a STATUS_MSG.
+
+The CAN controller will append a STATUS_MSG after the SEND_DATA as in 5.3.
+After receiving STATUS_MSG, the Main Controller will start a new SPI transfer
+for the requested amout of data.
+
+
+ Main ,'''''''''''''''''''''''''''''''''''''''''''''''''''|
+ (MOSI) '''| REQ_DATA |
+ |___________________________________________________|
+
+
+
+CAN Controller ,'''''''''''''''''''''''''''''',''''''''''''''|
+ | SEND DATA | STATUS |
+ | | |
+ `''''''''''''''''''''''''''''''`'''''''''''''
+
+- There is no place for the new message and/or the STATUS_MSG
+
+In this case, and because it is not allowed to fragment packets, the CAN
+controller must maintain assert the GPIO-IRQ line and wait until the Main
+Controller will start a new transfer again.
+
+5.6 Communication with upper layer
+----------------------------------
+
+After reception of data, the CAN-Main Controller driver should demux data and
+send them to the correct CAN interface via the API provided by socket CAN.
+
+6. Time synchronization
+----------------------------
+
+As the CAN controller sends a timestamp to the Main Controller, it is required
+to have the same time base. The CAN controller inserts timestamp with 1mSec
+resolution, because it is programmed with 1mSec timer interrupt.
+This resolution is enough for diagnostic protocols and higher resolution
+timestamps are not reliable inside the CAN controller itself.
+
+To allow to the Main Controller to compute the absolute time, the Main
+Controller and the CAN controller must compute elapsed time from the same base.
+
+The SYNC_MSG is used to reset the CAN controller's internal counter.
+The Main Controller sends this message at the start up, and it can send it
+when there is no traffic to maintain time synchronized.
+The following actions are taken:
+
+1. The Main Controller sends a SYNC_MSG, and stores its absolute time.
+ The SYNC_MSG is sent as single message in a 32 byte transfer.
+ The remaining bytes are filled with zeros by the Main Controller.
+ This makes easy to recognize the SYNC_MSG if the snchronization is lost.
+2. After receiving the SYNC_MSG, the CAN controller resets its internal
+ counter to zero.
+ As the SYNC_MSG is used to signalize the start of frame, the CAN controller
+ synchronize itself for the next transfer.
+
+When the CAN controller will send data, it will add the elapsed milliseconds
+from the receiving of the SYNC_MSG as timestamps. As 4 bytes are used for
+timestamp, the timestamp will roll over after 1193 days.
+
+7. CAN configuration
+----------------------------------
+
+It is foreseen that the CAN controller's CAN channels are configured in the
+usual way under Linux via the "ip" command. In fact, the CAN interface cannot
+be set to "up" if it was not configured before.
+
+With ip, the following parameters can be set:
+
+ip link set DEVICE type can
+ [ bitrate BITRATE [ sample-point SAMPLE-POINT] ] |
+ [ tq TQ prop-seg PROP_SEG phase-seg1 PHASE-SEG1
+ phase-seg2 PHASE-SEG2 [ sjw SJW ] ]
+
+ [ loopback { on | off } ]
+ [ listen-only { on | off } ]
+ [ triple-sampling { on | off } ]
+ [ one-shot { on | off } ]
+ [ berr-reporting { on | off } ]
+
+ [ restart-ms TIME-MS ]
+ [ restart ]
+
+ Where: BITRATE := { 1..1000000 }
+ SAMPLE-POINT := { 0.000..0.999 }
+ TQ := { NUMBER }
+ PROP-SEG := { 1..8 }
+ PHASE-SEG1 := { 1..8 }
+ PHASE-SEG2 := { 1..8 }
+ SJW := { 1..4 }
+ RESTART-MS := { 0 | NUMBER }
+
+After using the ip command, the driver will receive from the socketCAN layer
+the following structure, defined in include/linux/can/netlink.h:
+
+/*
+ * CAN bit-timing parameters
+ *
+ * For futher information, please read chapter "8 BIT TIMING
+ * REQUIREMENTS" of the "Bosch CAN Specification version 2.0"
+ * at http://www.semiconductors.bosch.de/pdf/can2spec.pdf.
+ */
+struct can_bittiming {
+ __u32 bitrate; /* Bit-rate in bits/second */
+ __u32 sample_point; /* Sample point in one-tenth of a percent */
+ __u32 tq; /* Time quanta (TQ) in nanoseconds */
+ __u32 prop_seg; /* Propagation segment in TQs */
+ __u32 phase_seg1; /* Phase buffer segment 1 in TQs */
+ __u32 phase_seg2; /* Phase buffer segment 2 in TQs */
+ __u32 sjw; /* Synchronisation jump width in TQs */
+ __u32 brp; /* Bit-rate prescaler */
+};
+
+The parameters are not interpreted by the driver, but they are encapsulated
+as they are in a SPI frame with MSG-ID=CFG_MSG_SET and sent to the corresponding CAN
+channel.
+It is then duty of the CAN controller to set up the hardware on base of
+the received parameters. According to the rules set in this document,
+single parameters are sent in a big-endian order (MSB first).
+
+A special case is the setup for the CFG channel. This channel is not mapped to
+a real CAN bus, but it is used to instantiate a communication
+between the CAN controller software and the Application in User Space.
+Data are not interpreted at all by the driver, and anybody can set its internal
+protocol to add commands and features to the CAN controller software.
+One example is the Watchdog triggering already mentioned.
+The CAN_MSG is ignored by the CAN controller for the CFG channel, and its values
+do not change the hardware setup.
+Using this message it is possible to switch the CAN controller between two
+operational modes:
+ - Supervisor / Maintenance mode: slow, max SPI frequency 1 Mhz
+ - User / Normal mode max SPI frequency set at startup
+
+The driver will start setting the SPI frequency to the lower value.
+When the CFG channel is opened, the driver checks the bitrate of the
+can_bittiming structure, and takes the following actions:
+
+ - bitrate = 125000 sets SPI frequency to low value
+ - bitrate > 125000 sets SPI frequency to high value
+
+In user space it is then possible to switch the CAN controller between the two
+operational modes simply issueing the "ip link" command and setting
+the bitrate for the CFG channel.
+
+To set the CAN controller in supervisor mode:
+ ip link set cfg type can bitrate 125000
+
+To set the CAN controller in user mode:
+ ip link set cfg type can bitrate 500000
+
+
+8. SPI Frame definition and Messages
+----------------------------------------
+
+A SPI Frame begins with a 4-bytes header:
+
+bytes:
+ 0 Message ID
+ 1-2 Message Length.
+ Length is computed including 2 bytes for checksum,
+ but without Message ID and Length itself.
+ 3 .. N-2 Depending on Message-ID
+ N-1 .. N Checksum
+
+Command codes:
+ 0x01 Status Request
+ 0x02 Send Data
+ 0x03 Sync message
+ 0x04 Configuration Message
+ .... t.b.d.
+
+8.1 Format of Send Data Message
+-------------------------------
+
+ _____,________________
+ | | ,''''''''''''''''',''''''''''''| ,'''''''|
+ |ID=2 | LENGTH | CAN MESSAGE |CAN MESSAGE | |CHECKSUM
+ |_____L________________|_________________|____________| L_______|
+ _.-' `--._
+ _,,-' ``-.._
+ _.-' `--._
+ _,--' ``-.._
+ ,.-' `-.._
+ ,'''''',''''''''''''','''''''''''''','''''',''''''| ,'''''''''|
+ | CH |TIMESTAMP | CAN ID |DLC |D[0] | |D[dlc-1] |
+ L______L_____________|______________L______|______| L_________|
+
+
+ Offset
+ 0 0x02 (SEND_DATA_MSG)
+ 1 - 2 Length of message
+
+
+Each CAN message has the following format
+
+ 0 Channel Number
+ Values:
+ 1-n CAN Channel
+ 0xFF CFG channel
+ 1 - 4 Timestamp
+ 5 - 8 can_id
+ 9 dlc (length of can message)
+ 10..N Variable number of data (max 8)
+
+Note: Channel 0 is reserved for configuration.
+
+The flag for Standard and Extended frame format (SFF and EFF
+in socketCAN framework) is a flag in the can_id.
+
+8.2 Format of Status Message
+----------------------------
+
+ _____,________________
+ | | ,''''''''''''''''''|'''''''|
+ |ID=1 | LENGTH=4 | Length (2 bytes) |CHECKSUM
+ |_____L________________|__________________|_______|
+
+
+ Offset
+ 0 0x01 (STATUS_MSG)
+ 1-2 4
+ 3-4 Desired mionimal length for next transfer
+ 5-6 Checksum
+
+8.3 Format of Sync Message
+--------------------------
+
+ _____,________________
+ | | ,'''''''''''''''''''|'''''''|
+ |ID=3 | LENGTH=6 | AA | 55 | 55 | AA |CHECKSUM
+ |_____L________________|____|____|____|____|_______|
+
+
+ Offset
+ 0 0x02 (SYNC_MSG)
+ 1-2 6
+ 3 0xAA
+ 4 0x55
+ 5 0x55
+ 6 0xAA
+ 7-8 Checksum
+
+8.5 Format of Set Configuration Message
+----------------------------------------
+ _____,________
+ | | ,'''''''''''''''''''''''''''''''''''''''''|'''''''''|..
+ |ID=4 | LEN=40 | channel | Enabled | bitrate | sample | tq | |CHECKSUM
+ |_____L________|_________|__________|__________|_________|_________..
+
+
+ Offset
+ 0 0x04 (CFG_MSG_SET)
+ 1-2 36
+ 3 channel number
+ 0xFF = CFG
+ 0..n = CAN controller CAN channel
+ 4 Enabled/disabled
+ Bit 0 is defined.
+ 0 = disabled
+ 1 = enabled
+ bit 1..7 = reserved (do not care)
+ 5-8 bitrate
+ 9-12 sample point
+ 13-16 Time quanta (tq)
+ 17-20 Propagation segment
+ 21-24 Phase Buffer segment 1
+ 25-28 Phase Buffer segment 2
+ 29-32 Sync jump width
+ 33-36 Bit rate prescaler
+ 37-40 ctrlmode
+ 41-42 Checksum
+
+There is no answer from the CAN controller after receiving a CFG_MSG_SET, and the
+CAN controller is not allowed to send a data frame in answer to a CFG_MSG_SET. After
+setting the channel, the communication will go on as usual.
+
+8.6 Format of REQ_DATA Message
+------------------------------
+
+ _____,________________
+ | | ,''''''''''''''''''''''''''|'''''''|
+ |ID=5 | LENGTH=n | 00 | 00 | 00 | |CHECKSUM
+ |_____L________________|____|____|____|___________|_______|
+
+
+ Offset
+ 0 0x05 (REQ_DATA)
+ 1-2 Length of the message.
+ This value is not fiixed and tells the CAN controller
+ how many bytes it can send back
+ 3:(n-2) Filled with zero
+ (n-1):n Checksum
+
+8.6 Format of Get Configuration Message
+----------------------------------------
+
+Format of the frame sent by Main Controller:
+ _____,________
+ | | ,'''''''''|'''''''''|
+ |ID=6 | LEN=3 | channel |CHECKSUM |
+ |_____L________|_________|_________|
+
+Answer from CAN Controller:
+ _____,________
+ | | ,''''''''''''''''''''|''''''''''|'''''''''|'''''''''|..
+ |ID=6 | LEN=25 | channel |tseg1_min |tseg2_max |tseg2_min| |CHECKSUM
+ |_____L________|_________|__________|__________|_________|_________..
+
+ Offset
+ 0 0x06 (CFG_MSG_GET)
+ 1-2 25
+ 3 channel number
+ 0xFF = CFG
+ 0..n = CAN controller CAN channel
+ 5 tseg1_min
+ 6 tseg1_max
+ 7 tseg2_min
+ 8 tseg2_max
+ 9 sjw_max
+ 10-13 brp_min
+ 14-17 brp_max
+ 18-21 brp_inc
+ 22 ctrlmode
+ 23-27 clock
+ 28-29 Checksum
+
+The CAN controller answers after receiving a CFG_MSG_GET with the can bittiming and
+capabilities. The meaning of bittiming is as explained in netlink.h for
+struct can_bittiming_const.
+
+ctrlmode contains the CAN controller capabilities. It is a wired-or byte, whose bits
+are defined in netlink.h.

[Stefano Babic]

This driver implements a simple protocol
to transfer CAN messages to and from an external
microcontroller via SPI interface.
Multiple busses can be tranfered on the same SPI channel.

It was tested on a i.MX35 connected to a Freescale's
HCS12 16-bit controller with 5 CAN busses.

Signed-off-by: Stefano Babic <***@denx.de>

---

Changes in v5:
- sort include headers
- match open parenthesis (globally fixed)
- add newline to dev_err() in insert_cfg_msg()
- use sizeof(*p)
- drop unused variable val in ISR
- proper return code instead of -1
- move device ids after probe/remove
- drop #ifdef CONFIG_OF (not needed anymore)
- use devm_ API
- use module_spi_driver()

Changes in v4:
- implement GET_CFG message to ask the microcontroller
for bittiming consts.
- drop set_mode (never called)
- drop echo_index (never used)
- fix inconsistencies using int variable (int/u32)
- add reference to documentation in Kconfig help
- s/refTime/ref_time/
- move module parameters on the top
- use variable to get sizeof inside kzalloc/memset
- fix missing close_candev() in open entry point
- fix return values (spi_can_fill_skb_msg())
- not access skb after calling net_receive_skb()
- fix minor coding style issues
- add missing free_irq() and gpio_free() in probe when fails

Changes in v3:
- spican.h renamed to spi_can.h
- drop further references to i.MX and HCS12, not yet cleaned
- drop CAN_DEV depend from Kconfig
- drop debug stuff via sysfs, not required in production code
- drop debug module parameter, use CAN_DEBUG_DEVICES
- drop unused bittiming constant
- chksum on as default. It could still be disabled via
DT/pdata, but not via module parameter.

Changes in v2:
- drop all references to i.MX35 and HCS12

drivers/net/can/spi/Kconfig | 11 +
drivers/net/can/spi/Makefile | 1 +
drivers/net/can/spi/spi_can.c | 1506 ++++++++++++++++++++++++++++++++++
include/linux/can/platform/spi_can.h | 33 +
4 files changed, 1551 insertions(+)
create mode 100644 drivers/net/can/spi/spi_can.c
create mode 100644 include/linux/can/platform/spi_can.h

diff --git a/drivers/net/can/spi/Kconfig b/drivers/net/can/spi/Kconfig
index 148cae5..e7323d2 100644
--- a/drivers/net/can/spi/Kconfig
+++ b/drivers/net/can/spi/Kconfig
@@ -7,4 +7,15 @@ config CAN_MCP251X
---help---
Driver for the Microchip MCP251x SPI CAN controllers.

+config CAN_SPI
+ tristate "Support for CAN over SPI"
+ ---help---
+ Driver to transfer CAN messages to a microcontroller
+ connected via the SPI interface using a simple messaged based
+ protocol.
+ Further information and details on the protocol can be found
+ in Documentation/networking/spi_can.txt
+
+ Say Y here if you want to support for CAN to SPI.
+
endmenu
diff --git a/drivers/net/can/spi/Makefile b/drivers/net/can/spi/Makefile
index 90bcacf..0fd2126 100644
--- a/drivers/net/can/spi/Makefile
+++ b/drivers/net/can/spi/Makefile
@@ -4,5 +4,6 @@


obj-$(CONFIG_CAN_MCP251X) += mcp251x.o
+obj-$(CONFIG_CAN_SPI) += spi_can.o

ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/spi/spi_can.c b/drivers/net/can/spi/spi_can.c
new file mode 100644
index 0000000..087e6b7
--- /dev/null
+++ b/drivers/net/can/spi/spi_can.c
@@ -0,0 +1,1506 @@
+/*
+ * (C) Copyright 2012-2014
+ * Stefano Babic, DENX Software Engineering, ***@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/can.h>
+#include <linux/gpio.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/netdevice.h>
+#include <linux/net_tstamp.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/platform/spi_can.h>
+
+#define MAX_CAN_CHANNELS 16
+#define CFG_CHANNEL 0xFF
+#define DRV_NAME "spican"
+#define DRV_VERSION "0.10"
+
+/* SPI constants */
+#define SPI_MAX_FRAME_LEN 1472 /* max total length of a SPI frame */
+#define BITS_X_WORD 32 /* 4 bytes */
+#define SPI_MIN_TRANSFER_LENGTH 32 /* Minimum SPI frame length */
+#define CAN_FRAME_MAX_DATA_LEN 8 /* max data lenght in a CAN message */
+#define MAX_ITERATIONS 100 /* Used to check if GPIO stucks */
+#define SPI_CAN_ECHO_SKB_MAX 4
+#define SLAVE_CLK_FREQ 100000000
+#define SLAVE_SUPERVISOR_FREQ ((u32)1000000)
+
+#define IS_GPIO_ACTIVE(p) (!!gpio_get_value(p->gpio) == p->gpio_active)
+#define MS_TO_US(ms) ((ms) * 1000)
+
+/* more RX buffers are required for delayed processing */
+#define SPI_RX_NBUFS MAX_CAN_CHANNELS
+
+/* Provide a way to disable checksum */
+static unsigned int chksum_en = 1;
+
+static unsigned int freq;
+module_param(freq, uint, 0);
+MODULE_PARM_DESC(freq,
+ "SPI clock frequency (default is set by platform device)");
+static unsigned int slow_freq;
+module_param(slow_freq, uint, 0);
+MODULE_PARM_DESC(slow_freq,
+ "SPI clock frequency to be used in supervisor mode (default 1 Mhz)");
+
+/* CAN channel status to drop not required frames */
+enum {
+ CAN_CHANNEL_DISABLED = 0,
+ CAN_CHANNEL_ENABLED = 1,
+};
+
+/* operational mode to set the SPI frequency */
+enum {
+ SLAVE_SUPERVISOR_MODE = 0,
+ SLAVE_USER_MODE = 1,
+};
+
+/* Message between Master and Slave
+ *
+ * see spi_can_spi.txt for details
+ *
+ * ,'''''''','''''''''''''''','''''''''''''''''''''''','''''''''''''|
+ * |MSG ID | Length(16 bit)| DATA | CHECKSUM |
+ * L________|________________|________________________|_____________|
+ */
+struct spi_can_frame_header {
+ u8 msgid;
+ u16 length;
+} __packed;
+
+struct spi_can_frame {
+ struct spi_can_frame_header header;
+ u8 data[1];
+} __packed;
+
+/* Message IDs for SPI Frame */
+enum msg_type {
+ SPI_MSG_STATUS_REQ = 0x01,
+ SPI_MSG_SEND_DATA = 0x02,
+ SPI_MSG_SYNC = 0x03,
+ SPI_MSG_CFG_SET = 0x04,
+ SPI_MSG_REQ_DATA = 0x05,
+ SPI_MSG_CFG_GET = 0x06
+};
+
+/* CAN data sent inside a
+ * SPI_MSG_SEND_DATA message
+ *
+ * _____,________________
+ * | | ,''''''''''''''''',''''''''''''| ,'''''''|
+ * |ID=2 | LENGTH | CAN MESSAGE |CAN MESSAGE | |CHECKSUM
+ * |_____L________________|_________________|____________| L_______|
+ * _.-' `--._
+ * _,,-' ``-.._
+ * _.-' `--._
+ * _,--' ``-.._
+ * ,.-' `-.._
+ * ,'''''',''''''''''''','''''''''''''','''''',''''''| ,'''''''''|
+ * | CH |TIMESTAMP | CAN ID |DLC |D[0] | |D[dlc-1] |
+ * L______L_____________|______________L______|______| L_________|
+ */
+
+struct msg_channel_data {
+ u8 channel;
+ u32 timestamp;
+ u32 can_id;
+ u8 dlc;
+ u8 data[8];
+} __packed;
+
+/* CFG message */
+struct msg_cfg_set_data {
+ u8 channel;
+ u8 enabled;
+ struct can_bittiming bt;
+} __packed;
+
+struct msg_cfg_get_data {
+ u8 channel;
+ u8 tseg1_min;
+ u8 tseg1_max;
+ u8 tseg2_min;
+ u8 tseg2_max;
+ u8 sjw_max;
+ u32 brp_min;
+ u32 brp_max;
+ u32 brp_inc;
+ u8 ctrlmode;
+ u32 clock_hz;
+} __packed;
+
+/* Status message */
+struct msg_status_data {
+ u16 length;
+} __packed;
+
+/* The ndo_start_xmit entry point
+ * insert the CAN messages into a list that
+ * is then read by the working thread.
+ */
+struct msg_queue_tx {
+ struct list_head list;
+ u32 channel;
+ u32 enabled;
+ struct sk_buff *skb;
+ enum msg_type type;
+};
+
+struct msg_queue_rx {
+ struct list_head list;
+ struct spi_can_frame *frame;
+ u32 len;
+ u32 bufindex;
+};
+
+struct spi_rx_data {
+ u8 __aligned(4) spi_rx_buf[SPI_MAX_FRAME_LEN];
+ u32 msg_in_buf;
+ struct mutex bufmutex;
+};
+
+/* Private data for the SPI device. */
+struct spi_can_data {
+ struct spi_device *spi;
+ u32 gpio;
+ u32 gpio_active;
+ u32 num_channels;
+ u32 freq;
+ u32 slow_freq;
+ u32 max_freq;
+ u32 slave_op_mode;
+ struct net_device *can_dev[MAX_CAN_CHANNELS + 1];
+ spinlock_t lock;
+ struct msg_queue_tx msgtx;
+ struct msg_queue_rx msgrx;
+ struct mutex lock_wqlist;
+ wait_queue_head_t wait;
+ struct workqueue_struct *wq;
+ struct work_struct work;
+ /* buffers must be 32-bit aligned ! */
+ u8 __aligned(4) spi_tx_buf[SPI_MAX_FRAME_LEN];
+ struct spi_rx_data rx_data[SPI_RX_NBUFS];
+ struct timeval ref_time;
+};
+
+/* Private data of the CAN devices */
+struct spi_can_priv {
+ struct can_priv can;
+ struct net_device *dev;
+ struct spi_can_data *spi_priv;
+ struct can_bittiming_const spi_can_bittiming_const;
+ u32 channel;
+ u32 devstatus;
+ u32 ctrlmode;
+};
+
+/* Pointer to the worker task */
+static struct task_struct *spi_can_task;
+
+#ifdef DEBUG
+static void dump_frame(u8 *buf, int len)
+{
+ int i;
+
+ for (i = 0; i < min(len, SPI_MAX_FRAME_LEN); i++) {
+ if (!(i % 16))
+ printk(KERN_ERR "\n0x%04X: ", i);
+ printk("0x%02x ", *buf++);
+ }
+ printk("\n");
+}
+#endif
+
+static inline u16 compute_checksum(char *buf, u32 len)
+{
+ u32 i;
+ u16 chksum = 0;
+
+ if (!chksum_en)
+ return 0;
+ for (i = 0; i < len; i++, buf++)
+ chksum += *buf;
+
+ return (~chksum + 1) & 0xFFFF;
+}
+
+static u32 verify_checksum(struct spi_device *spi, char *buf, u32 len)
+{
+ u32 i = 0;
+ u16 chksum = 0;
+ u16 received_checksum;
+ u32 nwords = 0;
+ u32 end = len - 2;
+ u32 val;
+
+ if (!chksum_en)
+ return 0;
+
+ if (!((u32)buf & 0x03)) {
+ nwords = (end / 4);
+ for (i = 0 ; i < nwords; i++, buf += 4) {
+ val = *(u32 *)buf;
+ chksum += (val & 0xFF) + ((val & 0xFF00) >> 8) +
+ ((val & 0xFF0000) >> 16) + (val >> 24);
+ }
+ }
+
+ for (i = nwords * 4; i < len - 2; i++, buf++)
+ chksum += *buf;
+
+ /* The last two bytes contain the checksum as 16 bit value */
+ received_checksum = *buf++;
+ received_checksum = (received_checksum << 8) + *buf;
+
+ if ((chksum + received_checksum) & 0xFFFF) {
+ dev_err(&spi->dev,
+ "Received wrong checksum: computed 0x%04x received 0x%04x\n",
+ chksum, received_checksum);
+ return -EPROTO;
+ }
+
+ return 0;
+}
+
+/* The protocol requires to send data in big-endian
+ * format. The processor can have a different endianess.
+ * Because the protocol uses 32 bits x word (bits sent
+ * in one chip select cycle), the function checks that the buffer
+ * length is a multiple of four.
+ */
+static int format_frame_output(char *buf, u32 len)
+{
+ u32 *p;
+ unsigned int cnt;
+
+ if (len % (BITS_X_WORD / 8))
+ return -1;
+
+ len /= (BITS_X_WORD / 8);
+ p = (u32 *)buf;
+
+ for (cnt = 0; cnt < len; cnt++, p++)
+ *p = cpu_to_be32(*p);
+
+ return 0;
+}
+
+static int format_frame_input(char *buf, u32 len)
+{
+ u32 *p;
+ unsigned int cnt;
+
+ if (len % (BITS_X_WORD / 8))
+ return -1;
+
+ len /= (BITS_X_WORD / 8);
+ p = (u32 *)buf;
+
+ for (cnt = 0; cnt < len; cnt++, p++)
+ *p = be32_to_cpu(*p);
+
+ return 0;
+}
+
+/* The processor manages 32-bit aligned buffer.
+ * At least 32 bytes are always sent.
+ * The function fills the buffer with trailing zero to fullfill
+ * these requirements
+ */
+static int fix_spi_len(char *buf, u32 len)
+{
+ unsigned int tmp;
+
+ if (len < SPI_MIN_TRANSFER_LENGTH) {
+ memset(&buf[len], 0, SPI_MIN_TRANSFER_LENGTH - len);
+ len = SPI_MIN_TRANSFER_LENGTH;
+ }
+
+ tmp = len % (BITS_X_WORD / 8);
+ if (tmp) {
+ tmp = (BITS_X_WORD / 8) - tmp;
+ memset(&buf[len], 0, tmp);
+ len += tmp;
+ }
+
+ return len;
+}
+
+static int check_rx_len(u32 len, u16 frame_len)
+{
+ if (frame_len > len ||
+ frame_len < sizeof(struct spi_can_frame_header))
+ return -1;
+
+ return 0;
+}
+
+static void spi_can_set_timestamps(struct sk_buff *skb,
+ struct msg_channel_data *msg)
+{
+ msg->timestamp = ktime_to_ns(skb->tstamp);
+}
+
+static struct net_device *candev_from_channel(struct spi_can_data *spi_data,
+ u8 channel)
+{
+ /* Last device is the CFG device */
+ if (channel == CFG_CHANNEL)
+ return spi_data->can_dev[spi_data->num_channels];
+ if (channel < spi_data->num_channels)
+ return spi_data->can_dev[channel];
+
+ return NULL;
+}
+
+static int insert_cfg_msg(struct net_device *dev, int enabled)
+{
+ struct spi_can_priv *priv = netdev_priv(dev);
+ struct spi_can_data *spi_priv = priv->spi_priv;
+ struct msg_queue_tx *tx_pkt;
+ unsigned long flags;
+
+ tx_pkt = kzalloc(sizeof(*tx_pkt), GFP_KERNEL);
+ if (!tx_pkt) {
+ dev_err(&dev->dev, "out of memory\n");
+ return -ENOMEM;
+ }
+ tx_pkt->channel = priv->channel;
+ tx_pkt->enabled = enabled;
+ tx_pkt->type = SPI_MSG_CFG_SET;
+
+ priv->devstatus = enabled;
+
+ spin_lock_irqsave(&spi_priv->lock, flags);
+ list_add_tail(&(tx_pkt->list), &(spi_priv->msgtx.list));
+ spin_unlock_irqrestore(&spi_priv->lock, flags);
+
+ /* Wakeup thread */
+ wake_up_interruptible(&spi_priv->wait);
+
+ return 0;
+}
+
+static int spi_can_open(struct net_device *dev)
+{
+ int ret;
+
+ ret = open_candev(dev);
+ if (ret)
+ return ret;
+
+ ret = insert_cfg_msg(dev, CAN_CHANNEL_ENABLED);
+ if (ret) {
+ close_candev(dev);
+ return ret;
+ }
+
+ netif_start_queue(dev);
+
+ return 0;
+}
+
+static int spi_can_close(struct net_device *dev)
+{
+ netif_stop_queue(dev);
+
+ insert_cfg_msg(dev, CAN_CHANNEL_DISABLED);
+
+ close_candev(dev);
+
+ return 0;
+}
+
+static int spi_can_hwtstamp_ioctl(struct net_device *netdev,
+ struct ifreq *ifr, int cmd)
+{
+ struct hwtstamp_config config;
+
+ if (copy_from_user(&config, ifr->ifr_data, sizeof(config)))
+ return -EFAULT;
+
+ if (config.flags)
+ return -EINVAL;
+
+ switch (config.tx_type) {
+ case HWTSTAMP_TX_OFF:
+ break;
+ case HWTSTAMP_TX_ON:
+ break;
+ default:
+ return -ERANGE;
+ }
+
+ switch (config.rx_filter) {
+ case HWTSTAMP_FILTER_NONE:
+ break;
+ default:
+ config.rx_filter = HWTSTAMP_FILTER_ALL;
+ break;
+ }
+
+ return copy_to_user(ifr->ifr_data, &config, sizeof(config)) ?
+ -EFAULT : 0;
+}
+
+static int spi_can_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
+{
+ if (!netif_running(dev))
+ return -EINVAL;
+
+ if (cmd == SIOCSHWTSTAMP)
+ return spi_can_hwtstamp_ioctl(dev, rq, cmd);
+
+ return -EINVAL;
+}
+
+static int spi_can_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct spi_can_priv *priv = netdev_priv(dev);
+ struct spi_can_data *spi_priv = priv->spi_priv;
+ struct msg_queue_tx *tx_pkt;
+ unsigned long flags;
+
+ if (can_dropped_invalid_skb(dev, skb))
+ return NETDEV_TX_OK;
+
+ tx_pkt = kzalloc(sizeof(*tx_pkt), GFP_KERNEL);
+ tx_pkt->channel = priv->channel;
+ tx_pkt->skb = skb;
+ tx_pkt->type = SPI_MSG_SEND_DATA;
+ INIT_LIST_HEAD(&(tx_pkt->list));
+
+ /* Add the incoming message to the end of the list */
+ spin_lock_irqsave(&spi_priv->lock, flags);
+ list_add_tail(&(tx_pkt->list), &(spi_priv->msgtx.list));
+ spin_unlock_irqrestore(&spi_priv->lock, flags);
+
+ /* Wakeup thread */
+ wake_up_interruptible(&spi_priv->wait);
+
+ return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops spi_can_netdev_ops = {
+ .ndo_open = spi_can_open,
+ .ndo_stop = spi_can_close,
+ .ndo_start_xmit = spi_can_start_xmit,
+ .ndo_do_ioctl = spi_can_ioctl,
+};
+
+/* GPIO Interrupt Handler.
+ * when the Slave has something to send, it raises
+ * an interrupt changing a GPIO. The handler does
+ * nothing else than waking up the worker.
+ */
+static irqreturn_t spi_can_irq(int irq, void *pdata)
+{
+ struct spi_can_data *spi_priv = (struct spi_can_data *)pdata;
+
+ /* Wakeup thread */
+ wake_up_interruptible(&spi_priv->wait);
+
+ return IRQ_HANDLED;
+}
+
+/* The parameters for SPI are fixed and cannot be changed due
+ * to hardware limitation in Slave.
+ * Only the frequency can be changed
+ */
+static void spi_can_initialize(struct spi_device *spi, u32 freq)
+{
+ /* Configure the SPI bus */
+ spi->mode = SPI_MODE_1;
+ spi->bits_per_word = BITS_X_WORD;
+ spi_setup(spi);
+}
+
+static int spi_can_transfer(struct spi_can_data *priv,
+ u32 bufindex, u32 len)
+{
+ struct spi_device *spi = priv->spi;
+ struct spi_message m;
+ struct spi_transfer t;
+ int ret = 0;
+
+ memset(&t, 0, sizeof(t));
+ t.tx_buf = priv->spi_tx_buf;
+ t.rx_buf = priv->rx_data[bufindex].spi_rx_buf;
+ t.len = len;
+ t.cs_change = 0;
+ if (priv->freq)
+ t.speed_hz = priv->freq;
+
+ spi_message_init(&m);
+ spi_message_add_tail(&t, &m);
+
+ ret = spi_sync(spi, &m);
+ if (ret)
+ dev_err(&spi->dev, "spi transfer failed\n");
+ return ret;
+}
+
+/* Prepare a SYNC message to synchronize with the start of frame */
+static u32 spi_can_spi_sync_msg(struct spi_can_data *spi_data, char *buf)
+{
+ struct spi_can_frame_header *header;
+ u32 len;
+
+ header = (struct spi_can_frame_header *)spi_data->spi_tx_buf;
+
+ header->msgid = SPI_MSG_SYNC;
+ *buf++ = 0xAA;
+ *buf++ = 0x55;
+ *buf++ = 0x55;
+ *buf++ = 0xAA;
+ len = 4;
+
+ do_gettimeofday(&spi_data->ref_time);
+
+ return len;
+}
+
+static int spi_can_fill_skb_msg(struct net_device *dev,
+ struct msg_channel_data *pcan,
+ struct timeval *timeref)
+{
+ struct spi_can_priv *priv = netdev_priv(dev);
+ struct net_device_stats *stats = &dev->stats;
+ struct can_frame *cf;
+ struct sk_buff *skb;
+ struct skb_shared_hwtstamps *shhwtstamps;
+ ktime_t tstamp;
+ u64 ns;
+
+ if (priv->devstatus != CAN_CHANNEL_ENABLED) {
+ dev_err(&dev->dev, "frame received when CAN deactivated\n");
+ return -EPERM;
+ }
+ skb = alloc_can_skb(dev, &cf);
+ if (unlikely(!skb)) {
+ stats->rx_dropped++;
+ return -ENOMEM;
+ }
+
+ cf->can_id = pcan->can_id;
+ cf->can_dlc = pcan->dlc;
+ memcpy(cf->data, pcan->data, pcan->dlc);
+
+ /* Set HW timestamps */
+ shhwtstamps = skb_hwtstamps(skb);
+ memset(shhwtstamps, 0, sizeof(*shhwtstamps));
+ ns = MS_TO_US(pcan->timestamp);
+ tstamp = ktime_add_us(timeval_to_ktime(*timeref), ns);
+ shhwtstamps->hwtstamp = tstamp;
+ skb->tstamp = tstamp;
+
+ stats->rx_packets++;
+ stats->rx_bytes += cf->can_dlc;
+ netif_receive_skb(skb);
+
+ return 0;
+}
+
+/* parse_can_msg gets all CAN messages encapsulated
+ * in a SEND_DATA message, and sends them upstream
+ */
+static int parse_can_msg(struct spi_can_data *spi_data,
+ struct spi_can_frame *frame,
+ u32 len)
+{
+ struct msg_channel_data *pcan;
+ char *pbuf = frame->data;
+ struct spi_device *spi = spi_data->spi;
+ struct net_device *netdev;
+ u32 can_msg_length;
+ int ret = 0;
+
+ while (len > 0) {
+ if (len < sizeof(struct msg_channel_data) -
+ CAN_FRAME_MAX_DATA_LEN) {
+ dev_err(&spi->dev,
+ "Received incompleted CAN message: length %d pbuf 0x%x\n",
+ len, *pbuf);
+ ret = -EBADMSG;
+ break;
+ }
+ pcan = (struct msg_channel_data *)pbuf;
+ if ((pcan->channel > spi_data->num_channels) &&
+ (pcan->channel != CFG_CHANNEL)) {
+ dev_err(&spi->dev,
+ "Frame with wrong channel %d, frame dropped",
+ pcan->channel);
+ ret = -EBADMSG;
+ break;
+ }
+
+ /* Check for a valid CAN message lenght */
+ if (pcan->dlc > CAN_FRAME_MAX_DATA_LEN) {
+ dev_err(&spi->dev,
+ "CAN message with wrong length: id 0x%x dlc %d",
+ pcan->can_id, pcan->dlc);
+ ret = -EBADMSG;
+ break;
+ }
+
+ pcan->can_id = be32_to_cpu(pcan->can_id);
+ pcan->timestamp = be32_to_cpu(pcan->timestamp);
+
+ /* Get the device corresponding to the channel */
+ netdev = candev_from_channel(spi_data, pcan->channel);
+
+ if (spi_can_fill_skb_msg(netdev, pcan, &spi_data->ref_time))
+ dev_err(&spi->dev,
+ "Error sending data to upper layer");
+ can_msg_length = (sizeof(struct msg_channel_data) + pcan->dlc -
+ CAN_FRAME_MAX_DATA_LEN);
+
+ len -= can_msg_length;
+ pbuf += can_msg_length;
+ }
+
+ return ret;
+}
+
+
+static void spi_can_extract_msg(struct spi_can_data *spi_data,
+ struct msg_queue_rx *msg)
+{
+ /* Extract all CAN messages, do not check
+ * the last two bytes as they are reserved for checksum
+ */
+ mutex_lock(&spi_data->rx_data[msg->bufindex].bufmutex);
+ if (parse_can_msg(spi_data, msg->frame, msg->len - 2) < 0) {
+#ifdef DEBUG
+ dump_frame(spi_data->rx_data[msg->bufindex].spi_rx_buf,
+ msg->len);
+#endif
+ }
+
+ /* I can now set the message as processed and decrease
+ * the number of messages in the SPI buffer.
+ * When all messages are processed, the TX thread
+ * can use the SPI buffer again
+ */
+ spi_data->rx_data[msg->bufindex].msg_in_buf--;
+ mutex_unlock(&spi_data->rx_data[msg->bufindex].bufmutex);
+}
+
+static void spi_can_rx_handler(struct work_struct *ws)
+{
+ struct spi_can_data *spi_data;
+ struct msg_queue_rx *msg;
+
+ spi_data = container_of(ws, struct spi_can_data, work);
+
+ while (1) {
+
+ if (list_empty(&spi_data->msgrx.list))
+ break;
+
+ mutex_lock(&spi_data->lock_wqlist);
+ msg = list_first_entry(&spi_data->msgrx.list,
+ struct msg_queue_rx, list);
+ list_del(&msg->list);
+ mutex_unlock(&spi_data->lock_wqlist);
+
+ spi_can_extract_msg(spi_data, msg);
+ kfree(msg);
+ }
+}
+
+/* This is called in overload condition to process a siongle frame and
+ * free a SPI frame for transfer
+ * This is called by the thread
+ */
+static void spi_can_process_single_frame(struct spi_can_data *spi_data,
+ u32 index)
+{
+ struct list_head *pos;
+ struct msg_queue_rx *msg;
+ unsigned int found = 0, freed;
+
+ mutex_lock(&spi_data->lock_wqlist);
+ list_for_each(pos, &spi_data->msgrx.list) {
+ msg = list_entry(pos, struct msg_queue_rx, list);
+ if (msg->bufindex == index) {
+ found = 1;
+ break;
+ }
+ }
+
+ /* Drop the message from the list */
+ if (found)
+ list_del(&msg->list);
+ mutex_unlock(&spi_data->lock_wqlist);
+
+ if (!found) {
+
+ /* I cannot parse the buffer because it is worked
+ * by another task, check when it is finished
+ */
+
+ do {
+ mutex_lock(&spi_data->rx_data[index].bufmutex);
+ freed = (spi_data->rx_data[index].msg_in_buf == 0);
+ mutex_unlock(&spi_data->rx_data[index].bufmutex);
+ } while (!freed);
+
+ return;
+ }
+
+ spi_can_extract_msg(spi_data, msg);
+
+}
+
+static int spi_can_process_get(struct spi_can_data *spi_data,
+ struct msg_cfg_get_data *msg)
+{
+ struct spi_can_priv *priv;
+ struct net_device *dev;
+ int index;
+ struct can_bittiming_const *bittiming;
+ int ret = -ENODEV;
+
+ index = msg->channel;
+ if (index != CFG_CHANNEL && index >= spi_data->num_channels)
+ return -ENODEV;
+
+ dev = alloc_candev(sizeof(struct spi_can_priv), 0);
+ if (!dev)
+ return -ENOMEM;
+
+ bittiming = kzalloc(sizeof(*bittiming), GFP_KERNEL);
+ if (!bittiming) {
+ free_candev(dev);
+ return -ENOMEM;
+ }
+
+ /* Get the pointer to the driver data */
+ priv = netdev_priv(dev);
+
+ /* Last channel is used for configuration only */
+ if (index == CFG_CHANNEL) {
+ strncpy(dev->name, "cfg", IFNAMSIZ);
+ priv->channel = CFG_CHANNEL;
+ } else {
+ snprintf(dev->name, IFNAMSIZ, "hcan%d", index);
+ priv->channel = index;
+ spi_data->num_channels++;
+ }
+
+ dev->netdev_ops = &spi_can_netdev_ops;
+
+ priv->spi_priv = spi_data;
+ priv->dev = dev;
+ priv->devstatus = CAN_CHANNEL_DISABLED;
+
+ /* In most cases, only the bitrate can be set
+ * on the remote microcontroller.
+ * The driver asks anyway for the timing
+ * and fill the bittiming_const structure
+ */
+
+ priv->can.clock.freq = be32_to_cpu(msg->clock_hz);
+ bittiming->tseg1_min = msg->tseg1_min;
+ bittiming->tseg1_max = msg->tseg1_max;
+ bittiming->tseg2_min = msg->tseg2_min;
+ bittiming->tseg2_max = msg->tseg2_max;
+ bittiming->sjw_max = msg->sjw_max;
+ bittiming->brp_min = be32_to_cpu(msg->brp_min);
+ bittiming->brp_max = be32_to_cpu(msg->brp_max);
+ bittiming->brp_inc = be32_to_cpu(msg->brp_inc);
+
+ priv->can.bittiming_const = bittiming;
+
+ priv->ctrlmode = msg->ctrlmode & 0x7F;
+
+ ret = register_candev(dev);
+ if (ret) {
+ dev_err(&spi_data->spi->dev,
+ "registering netdev %d failed with 0x%x\n",
+ index, ret);
+ free_candev(dev);
+ return -ENODEV;
+ }
+
+ if (index != CFG_CHANNEL)
+ spi_data->can_dev[index] = dev;
+ else
+ spi_data->can_dev[spi_data->num_channels] = dev;
+
+ dev_info(&spi_data->spi->dev, "CAN device %d registered\n",
+ index);
+
+ return 0;
+}
+
+static int spi_can_receive(struct spi_can_data *spi_data,
+ int len, u32 bufindex, u16 *req_bytes)
+{
+ unsigned int i, start = 0;
+ char *pbuf, *pspibuf;
+ struct spi_can_frame *frame;
+ struct msg_status_data *status_msg;
+ struct msg_cfg_get_data *getcfg_msg;
+ struct msg_queue_rx *rxmsg;
+ u16 rx_len;
+ struct spi_device *spi = spi_data->spi;
+ u32 rx_frames = 0;
+
+ pspibuf = spi_data->rx_data[bufindex].spi_rx_buf;
+ format_frame_input(pspibuf, len);
+
+ /* Requested bytes for next SPI frame.
+ * The value is updated by a SEND_STATUS message.
+ */
+ *req_bytes = 0;
+
+ while ((len - start) > 1) {
+ /* first search for start of frame */
+ for (i = start; i < len; i++) {
+ if (pspibuf[i] != 0)
+ break;
+ }
+
+ /* No more frame to be examined */
+ if (i == len)
+ return rx_frames;
+
+ /* Set start in the buffer for next iteration */
+ start = i;
+
+ frame = (struct spi_can_frame *)&pspibuf[i];
+ switch (frame->header.msgid) {
+ case SPI_MSG_STATUS_REQ:
+ status_msg = (struct msg_status_data *)frame->data;
+ rx_len = be16_to_cpu(status_msg->length);
+ *req_bytes = rx_len;
+ rx_frames++;
+ break;
+
+ case SPI_MSG_SEND_DATA:
+ rx_len = be16_to_cpu(frame->header.length);
+ if (check_rx_len(len - start, rx_len)) {
+ dev_err(&spi->dev,
+ "Frame fragmented received, frame dropped\n");
+#ifdef DEBUG
+ dump_frame(pspibuf, len);
+#endif
+ return -EPROTO;
+ }
+ if (verify_checksum(spi, (char *)frame,
+ rx_len + sizeof(frame->header)) < 0)
+ return -EPROTO;
+ pbuf = frame->data;
+
+ /* Put the recognized frame into the receive list
+ * to be processed by the workqueue
+ */
+ rxmsg = kzalloc(sizeof(*rxmsg),
+ GFP_KERNEL);
+ if (!rxmsg) {
+ dev_err(&spi->dev, "out of memory");
+ return -ENOMEM;
+ }
+ rxmsg->frame = frame;
+ rxmsg->len = rx_len;
+ rxmsg->bufindex = bufindex;
+
+ /* Add the frame to be processed to the rx list */
+ mutex_lock(&spi_data->lock_wqlist);
+ spi_data->rx_data[bufindex].msg_in_buf++;
+ if (spi_data->rx_data[bufindex].msg_in_buf > 1)
+ dev_err(&spi->dev, "More as one SEND_DATA\n");
+ list_add_tail(&(rxmsg->list), &spi_data->msgrx.list);
+ mutex_unlock(&spi_data->lock_wqlist);
+
+ rx_frames++;
+ break;
+
+ case SPI_MSG_CFG_GET:
+ getcfg_msg = (struct msg_cfg_get_data *)frame->data;
+ rx_len = be16_to_cpu(frame->header.length);
+ if (check_rx_len(len - start, rx_len) &&
+ rx_len != sizeof(*getcfg_msg)) {
+ dev_err(&spi->dev,
+ "Broken GET CFG frame\n");
+#ifdef DEBUG
+ dump_frame(pspibuf, len);
+#endif
+ return -EPROTO;
+ }
+
+ spi_can_process_get(spi_data, getcfg_msg);
+ rx_frames++;
+ break;
+
+ default:
+ dev_err(&spi->dev, "wrong frame received with MSG-ID=0x%x\n",
+ frame->header.msgid);
+#ifdef DEBUG
+ dump_frame(pspibuf, len);
+#endif
+ return -EPROTO;
+ }
+
+ rx_len += sizeof(frame->header);
+ start += rx_len;
+ }
+
+ return rx_frames;
+}
+
+/* The function sends setup for the
+ * CAN channel. No answer is allowed from Slave,
+ * as this is a high-priority message.
+ */
+static u32 spi_can_cfg(struct spi_can_data *spi_data,
+ struct msg_queue_tx *msg, char *buf)
+{
+ struct net_device *dev;
+ struct spi_can_priv *priv;
+ struct msg_cfg_set_data can_cfg;
+ struct spi_device *spi = spi_data->spi;
+ int i;
+ u32 *pbe_bt, *pbt;
+ u8 channel;
+
+ channel = msg->channel & 0xFF;
+
+ can_cfg.channel = channel;
+ can_cfg.enabled = msg->enabled;
+
+ dev = candev_from_channel(spi_data, channel);
+ priv = netdev_priv(dev);
+
+ /* Configuration values are interpreted by the Slave
+ * firmware only. Values on the SPI line are in big
+ * endian order and must be converted before to be put
+ * on the line.
+ */
+ for (i = 0, pbe_bt = (u32 *)&can_cfg.bt,
+ pbt = (u32 *)&priv->can.bittiming;
+ i < (sizeof(struct can_bittiming) / sizeof(*pbe_bt));
+ i += sizeof(u32)) {
+ *pbe_bt++ = cpu_to_be32(*pbt++);
+ }
+
+ memcpy(buf, &can_cfg, sizeof(can_cfg));
+
+ if (channel == CFG_CHANNEL) {
+ u32 changed = 0;
+
+ switch (spi_data->slave_op_mode) {
+ case SLAVE_SUPERVISOR_MODE:
+ if (priv->can.bittiming.bitrate > 125000) {
+ spi_data->freq = spi_data->max_freq;
+ spi_data->slave_op_mode = SLAVE_USER_MODE;
+ changed = 1;
+ }
+ break;
+ case SLAVE_USER_MODE:
+ if (priv->can.bittiming.bitrate <= 125000) {
+ spi_data->freq = spi_data->slow_freq;
+ spi_data->slave_op_mode = SLAVE_SUPERVISOR_MODE;
+ changed = 1;
+ }
+ break;
+ default:
+ dev_err(&spi_data->spi->dev, "Erroneous Slave OP Mode %d\n",
+ spi_data->slave_op_mode);
+ spi_data->slave_op_mode = SLAVE_SUPERVISOR_MODE;
+ }
+ if (changed) {
+ spi_can_initialize(spi, spi_data->freq);
+ dev_info(&spi->dev,
+ "Slave into %s mode, SPI frequency set to %d\n",
+ (spi_data->slave_op_mode == SLAVE_USER_MODE) ?
+ "User" : "Supervisor",
+ spi_data->freq);
+ }
+ }
+
+ return sizeof(struct msg_cfg_set_data);
+}
+
+static int spi_send_getcfg(struct spi_can_data *spi_data,
+ struct msg_queue_tx *msg, char *buf)
+{
+
+ struct msg_cfg_get_data *query_msg;
+ u32 len;
+
+ /* Prepare MSG_CFG_GET to ask bit timing constants */
+ query_msg = (struct msg_cfg_get_data *)buf;
+ memset(query_msg, 0, sizeof(*query_msg));
+ query_msg->channel = msg->channel;
+
+ len = sizeof(*query_msg);
+
+ return len;
+}
+
+static u32 spi_can_send_data(struct spi_can_data *spi_data,
+ struct msg_queue_tx *msg, char *buf)
+{
+ struct sk_buff *skb;
+ struct msg_channel_data can_spi_msg;
+ struct can_frame *frame;
+ u16 len = 0;
+ struct spi_can_priv *priv;
+ struct net_device *dev;
+ struct net_device_stats *stats;
+
+ /* Encapsulate the CAN message inside the SPI frame */
+ skb = msg->skb;
+ frame = (struct can_frame *)skb->data;
+ if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
+ frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;
+
+ can_spi_msg.channel = msg->channel & 0xFF;
+
+ spi_can_set_timestamps(skb, &can_spi_msg);
+
+ can_spi_msg.can_id = cpu_to_be32(frame->can_id);
+ can_spi_msg.dlc = frame->can_dlc;
+ memcpy(can_spi_msg.data,
+ frame->data, frame->can_dlc);
+ len = sizeof(struct msg_channel_data) +
+ frame->can_dlc - CAN_FRAME_MAX_DATA_LEN;
+ memcpy(buf, &can_spi_msg, len);
+
+ dev = candev_from_channel(spi_data, can_spi_msg.channel);
+ priv = netdev_priv(dev);
+
+ /* Update statistics for device */
+ stats = &dev->stats;
+ stats->tx_bytes += frame->can_dlc;
+ stats->tx_packets++;
+ netif_wake_queue(dev);
+
+ return len;
+}
+
+static int spi_can_thread(void *data)
+{
+ struct spi_can_data *spi_data = (struct spi_can_data *)data;
+ u16 len = 0;
+ u16 alen = 0;
+ u16 req_bytes = 0;
+ u32 cnt = 0, resync_required = 1;
+ u32 bufindex = 0;
+ int rx_frames;
+ struct msg_queue_tx *msg, *tmp;
+ char *buf;
+ struct spi_can_frame_header *header;
+ u16 chksum;
+ unsigned long flags;
+ struct spi_device *spi = spi_data->spi;
+
+ /* Only to zero the whole buffers */
+ len = SPI_MAX_FRAME_LEN;
+
+ while (1) {
+ if (kthread_should_stop())
+ break;
+
+ if (spi_data->rx_data[bufindex].msg_in_buf)
+ spi_can_process_single_frame(spi_data, bufindex);
+
+ /* Clear buffers from last transfer */
+ memset(spi_data->spi_tx_buf, 0, len);
+
+ len = 0;
+ header = (struct spi_can_frame_header *)spi_data->spi_tx_buf;
+ buf = ((struct spi_can_frame *)spi_data->spi_tx_buf)->data;
+
+ /* There is not yet any message */
+ header->msgid = 0;
+
+ /* getting CAN message from upper layer */
+ spin_lock_irqsave(&spi_data->lock, flags);
+ list_for_each_entry_safe(msg, tmp,
+ &spi_data->msgtx.list, list) {
+
+ /* we cannot mix messages of different type.
+ * If the new request is of different type,
+ * stop scanning the list
+ * and send the actual message first
+ */
+ if (header->msgid && (header->msgid != msg->type ||
+ header->msgid == SPI_MSG_CFG_GET))
+ break;
+
+ /* Extract packet and remove it from the list */
+ list_del(&msg->list);
+
+ alen = 0;
+
+ switch (msg->type) {
+
+ case SPI_MSG_SEND_DATA:
+ /* There are data to be sent */
+ header->msgid = SPI_MSG_SEND_DATA;
+ alen = spi_can_send_data(spi_data, msg, buf);
+ break;
+
+ case SPI_MSG_CFG_SET:
+ header->msgid = SPI_MSG_CFG_SET;
+ alen = spi_can_cfg(spi_data, msg, buf);
+ break;
+
+ case SPI_MSG_CFG_GET:
+ header->msgid = SPI_MSG_CFG_GET;
+ alen = spi_send_getcfg(spi_data, msg, buf);
+ break;
+
+ default:
+ dev_err(&spi->dev,
+ "Message to Slave wrong: type %d",
+ msg->type);
+ }
+
+ /* Update total length with length of CAN message */
+ len += alen;
+ buf += alen;
+
+ /* Free the memory for message, not used anymore */
+ if (msg->skb)
+ kfree_skb(msg->skb);
+ kfree(msg);
+
+ /* Check if there is enough place for other messages
+ * else messages will be transfered in the next
+ * iteration
+ */
+ if ((len + sizeof(chksum) +
+ sizeof(*header) +
+ sizeof(u32)) >= SPI_MAX_FRAME_LEN)
+ break;
+ }
+ spin_unlock_irqrestore(&spi_data->lock, flags);
+
+ /* Check if a resync is required. It is sent
+ * the first time the thread is started and when an error
+ * is recognized. Not required if data must be sent.
+ */
+ if (!len) {
+ if (resync_required) {
+ len = spi_can_spi_sync_msg(spi_data, buf);
+ resync_required = 0;
+ } else {
+ header->msgid = SPI_MSG_REQ_DATA;
+ len = max(req_bytes,
+ (u16)((SPI_MIN_TRANSFER_LENGTH) -
+ sizeof(*header) -
+ sizeof(u16) /* checksum */));
+ }
+ buf += len;
+ } else {
+ int delta = req_bytes - len;
+
+ if ((delta > 0) &&
+ (header->msgid == SPI_MSG_SEND_DATA)) {
+
+ /* buf points to the next CAN message */
+ buf += delta;
+ len += delta;
+ }
+ }
+
+ /* Take into account CHECKSUM
+ * MSGID and LENGTH are not computed in the lenght field
+ */
+ len += sizeof(chksum);
+ header->length = cpu_to_be16(len);
+ len += sizeof(*header);
+
+ /* Compute checksum */
+ chksum = compute_checksum(spi_data->spi_tx_buf,
+ len - sizeof(chksum));
+ chksum = cpu_to_be16(chksum);
+ memcpy(buf, &chksum, sizeof(chksum));
+
+ len = fix_spi_len(spi_data->spi_tx_buf, len);
+
+ format_frame_output(spi_data->spi_tx_buf, len);
+
+ spi_can_transfer(spi_data, bufindex, len);
+ rx_frames = spi_can_receive(spi_data, len, bufindex,
+ &req_bytes);
+
+ /* Trigger the workqueue for RX processing */
+ queue_work(spi_data->wq, &spi_data->work);
+
+ if (rx_frames < 0)
+ resync_required = 1;
+
+ bufindex++;
+ if (bufindex == SPI_RX_NBUFS)
+ bufindex = 0;
+
+ /* Check if the GPIO is still set,
+ * because the Slave wants to send more data
+ */
+ if (IS_GPIO_ACTIVE(spi_data) && (rx_frames <= 0)) {
+ cnt++;
+ if (cnt > MAX_ITERATIONS) {
+ dev_err(&spi->dev,
+ "GPIO stuck ! Send SYNC message");
+ resync_required = 1;
+ cnt = 0;
+ }
+ } else {
+ cnt = 0;
+ }
+
+ wait_event_interruptible(spi_data->wait,
+ (!list_empty(&spi_data->msgtx.list) ||
+ IS_GPIO_ACTIVE(spi_data) ||
+ resync_required) ||
+ (req_bytes > 0) ||
+ kthread_should_stop());
+ }
+
+ return 0;
+}
+
+static int spi_can_probe(struct spi_device *spi)
+{
+ struct spi_can_platform_data *pdata = spi->dev.platform_data;
+ int ret = -ENODEV;
+ struct spi_can_data *spi_data;
+ int index;
+ u32 can_channels;
+ u32 active = GPIO_ACTIVE_LOW;
+ u32 data_gpio;
+ u32 flags;
+ struct msg_queue_tx *tx_pkt;
+
+ if (spi->dev.of_node) {
+ if (of_property_read_u32(spi->dev.of_node,
+ "channels", &can_channels))
+ return -ENODEV;
+ if (!slow_freq) {
+ of_property_read_u32(spi->dev.of_node,
+ "slowfreq", &slow_freq);
+ }
+ if (!freq) {
+ of_property_read_u32(spi->dev.of_node,
+ "freq", &freq);
+ }
+ of_property_read_u32(spi->dev.of_node,
+ "chksum_en", &chksum_en);
+ data_gpio = of_get_gpio_flags(spi->dev.of_node,
+ 0, &flags);
+ active = (flags & GPIO_ACTIVE_LOW) ? 0 : 1;
+ } else {
+ if (!pdata || (pdata->can_channels < 0) ||
+ (pdata->can_channels > MAX_CAN_CHANNELS))
+ return -ENODEV;
+ if (pdata->slow_freq)
+ slow_freq = pdata->slow_freq;
+ data_gpio = pdata->gpio;
+ active = pdata->active;
+ can_channels = pdata->can_channels;
+ chksum_en = pdata->chksum_en;
+ }
+
+ if (!gpio_is_valid(data_gpio)) {
+ dev_err(&spi->dev,
+ "Wrong data valid GPIO: %d\n",
+ data_gpio);
+ return -EINVAL;
+ }
+
+ dev_info(&spi->dev, "Channels: %d, gpio %d active %s\n",
+ can_channels,
+ data_gpio,
+ active ? "high" : "low");
+ /* It is possible to adjust frequency at loading time
+ * if the driver is compiled as module
+ */
+ if (freq) {
+ if (freq > spi->max_speed_hz) {
+ dev_err(&spi->dev,
+ "Frequency too high: %d Hz > %d Hz. Falling back to %d\n",
+ freq,
+ spi->max_speed_hz,
+ spi->max_speed_hz);
+ freq = spi->max_speed_hz;
+ }
+ }
+
+ /* Check if the supervisor frequency is passed as parameter
+ * Fallback to 1 Mhz
+ */
+ if (!slow_freq)
+ slow_freq = SLAVE_SUPERVISOR_FREQ;
+
+ if ((freq && (slow_freq > freq)) ||
+ (slow_freq > SLAVE_SUPERVISOR_FREQ)) {
+ dev_err(&spi->dev,
+ "Supervisor frequency too high: %d Hz > %d Hz. Falling back to %d\n",
+ slow_freq,
+ min(freq, SLAVE_SUPERVISOR_FREQ),
+ min(freq, SLAVE_SUPERVISOR_FREQ));
+ slow_freq = min(freq, SLAVE_SUPERVISOR_FREQ);
+ }
+
+ ret = devm_gpio_request(&spi->dev, data_gpio, "spican-irq");
+ if (ret) {
+ dev_err(&spi->dev,
+ "gpio %d cannot be acquired\n",
+ data_gpio);
+ return -ENODEV;
+ }
+
+ /* The SPI structure is common to all CAN devices */
+ spi_data = (struct spi_can_data *)
+ devm_kzalloc(&spi->dev, sizeof(struct spi_can_data),
+ GFP_KERNEL | __GFP_ZERO);
+ if (!spi_data)
+ return -ENOMEM;
+
+ INIT_LIST_HEAD(&spi_data->msgtx.list);
+ INIT_LIST_HEAD(&spi_data->msgrx.list);
+
+ /* Get the GPIO used as interrupt. The Slave raises
+ * an interrupt when there are messages to be sent
+ */
+ gpio_direction_input(data_gpio);
+ ret = devm_request_irq(&spi->dev, gpio_to_irq(data_gpio), spi_can_irq,
+ (active ? IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING) ,
+ "spican-rx", spi_data);
+ if (ret)
+ return -ENODEV;
+
+ spi_data->num_channels = can_channels;
+ spi_data->gpio = data_gpio;
+ spi_data->gpio_active = active;
+ spi_data->spi = spi;
+ spi_data->max_freq = freq;
+ spi_data->slow_freq = slow_freq;
+ spi_data->freq = slow_freq;
+ spi_data->slave_op_mode = SLAVE_SUPERVISOR_MODE;
+ spin_lock_init(&spi_data->lock);
+ mutex_init(&spi_data->lock_wqlist);
+ for (index = 0; index < SPI_RX_NBUFS; index++)
+ mutex_init(&spi_data->rx_data[index].bufmutex);
+
+ /* Initialize SPI interface */
+ dev_set_drvdata(&spi->dev, spi_data);
+ spi_can_initialize(spi, freq);
+
+ /* Now ask the thread to send a GET_CFG to all interfaces */
+ for (index = 0; index < (can_channels + 1); index++) {
+ tx_pkt = kzalloc(sizeof(*tx_pkt), GFP_KERNEL);
+ if (!tx_pkt)
+ return -ENOMEM;
+
+ if (index != can_channels)
+ tx_pkt->channel = index;
+ else
+ tx_pkt->channel = CFG_CHANNEL;
+ tx_pkt->type = SPI_MSG_CFG_GET;
+ list_add_tail(&(tx_pkt->list), &(spi_data->msgtx.list));
+ }
+
+ init_waitqueue_head(&spi_data->wait);
+ /* Initialize work que for RX background processing */
+ spi_data->wq = alloc_workqueue("spican_wq",
+ WQ_HIGHPRI | WQ_MEM_RECLAIM, 1);
+ INIT_WORK(&spi_data->work, spi_can_rx_handler);
+
+ spi_can_task = kthread_run(spi_can_thread, spi_data, "kspican");
+ if (!spi_can_task) {
+ ret = -EIO;
+ goto failed_start_task;
+ }
+
+ dev_info(&spi->dev, "%s version %s initialized\n",
+ DRV_NAME, DRV_VERSION);
+ dev_info(&spi->dev, "SPI frequency %d, supervisor frequency %d : now set to %d\n",
+ spi_data->max_freq, spi_data->slow_freq, spi_data->freq);
+
+ return 0;
+
+failed_start_task:
+
+ return ret;
+}
+
+static int spi_can_remove(struct spi_device *spi)
+{
+ struct spi_can_data *priv = dev_get_drvdata(&spi->dev);
+ int index;
+
+ if (spi_can_task)
+ kthread_stop(spi_can_task);
+ if (priv->wq) {
+ flush_workqueue(priv->wq);
+ destroy_workqueue(priv->wq);
+ }
+
+ for (index = 0; index < (priv->num_channels + 1); index++) {
+ if (priv->can_dev[index]) {
+ unregister_candev(priv->can_dev[index]);
+ free_candev(priv->can_dev[index]);
+ }
+ }
+
+ return 0;
+}
+
+static const struct spi_device_id spi_can_ids[] = {
+ { "spican", 0},
+ { "canoverspi", 0},
+ { },
+};
+MODULE_DEVICE_TABLE(spi, spi_can_ids);
+
+static struct spi_driver spi_can_driver = {
+ .probe = spi_can_probe,
+ .remove = spi_can_remove,
+ .id_table = spi_can_ids,
+ .driver = {
+ .name = DRV_NAME,
+ .bus = &spi_bus_type,
+ .owner = THIS_MODULE,
+ },
+};
+module_spi_driver(spi_can_driver);
+
+MODULE_AUTHOR("Stefano Babic <***@denx.de");
+MODULE_DESCRIPTION("CAN over SPI driver");
+MODULE_LICENSE("GPL v2");
+MODULE_VERSION(DRV_VERSION);
diff --git a/include/linux/can/platform/spi_can.h b/include/linux/can/platform/spi_can.h
new file mode 100644
index 0000000..95ee330
--- /dev/null
+++ b/include/linux/can/platform/spi_can.h
@@ -0,0 +1,33 @@
+/*
+ * (C) Copyright 2010-2014
+ * Stefano Babic, DENX Software Engineering, ***@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __CAN_PLATFORM_SPICAN_H__
+#define __CAN_PLATFORM_SPICAN_H__
+
+#include <linux/spi/spi.h>
+
+struct spi_can_platform_data {
+ u32 can_channels;
+ u32 gpio;
+ u32 active;
+ unsigned int slow_freq;
+ unsigned int chksum_en;
+};
+
+#endif

[Stefano Babic]

Hi everybody,

has the last version fixed all open issues ? Maybe is it ready to be
applied ;-) ?

Thanks,
Stefano

Hi all,
after some time, I post an updated version of the spi_can driver.
Sorry for that, but I had to wait for the requested modifications
on the microcontroller's firmware to test it again.
The majork change is the GET_CFG message to query the remote
CAN microcontroller for the CAN bittiming. I hope also I have fixed
all issues from previous reviews.
- drop Patch 2/3, already applied.
- sort include headers
- match open parenthesis (globally fixed)
- add newline to dev_err() in insert_cfg_msg()
- use sizeof(*p)
- drop unused variable val in ISR
- proper return code instead of -1
- move device ids after probe/remove
- drop #ifdef CONFIG_OF (not needed anymore)
- use devm_ API
- use module_spi_driver()
- added GET_CFG message to query bit timing to the remote controller.
- implement GET_CFG message to ask the microcontroller
for bittiming consts.
- drop set_mode (never called)
- drop echo_index (never used)
- fix inconsistencies using int variable (int/u32)
- add reference to documentation in Kconfig help
- s/refTime/ref_time/
- move module parameters on the top
- use variable to get sizeof inside kzalloc/memset
- fix missing close_candev() in open entry point
- fix return values (spi_can_fill_skb_msg())
- not access skb after calling net_receive_skb()
- fix minor coding style issues
- add missing free_irq() and gpio_free() in probe when fails
- format documentation, check for lines > 80 chars (O. Hartkopp)
- patch 2/3 already aqpplied to can-next, removed from patchset
- spican.h renamed to spi_can.h
- drop further references to i.MX and HCS12, not yet cleaned
- drop CAN_DEV depend from Kconfig
- drop debug stuff via sysfs, not required in production code
- drop debug module parameter, use CAN_DEBUG_DEVICES
- drop unused bittiming constant
- chksum on as default. It could still be disabled via
DT/pdata, but not via module parameter.
- drop all references to i.MX35 and HCS12
Add documentation for SPI to CAN driver
CAN: CAN driver to support multiple CAN bus on SPI interface
Documentation/networking/spi_can.txt | 774 +++++++++++++++++
drivers/net/can/spi/Kconfig | 11 +
drivers/net/can/spi/Makefile | 1 +
drivers/net/can/spi/spi_can.c | 1506 ++++++++++++++++++++++++++++++++++
include/linux/can/platform/spi_can.h | 33 +
5 files changed, 2325 insertions(+)
create mode 100644 Documentation/networking/spi_can.txt
create mode 100644 drivers/net/can/spi/spi_can.c
create mode 100644 include/linux/can/platform/spi_can.h

--
=====================================================================
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: [phone] Fax: [phone] Email: ***@denx.de
=====================================================================
--
To unsubscribe from this list: send the line "unsubscribe linux-can" in
the body of a message to ***@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html

[Stefano Babic]

Hi,

Post by Stefano Babic
Hi everybody,
has the last version fixed all open issues ? Maybe is it ready to be
applied ;-) ?
Thanks,
Stefano

Ping ?

Best regards,
Stefano Babic

Post by Stefano Babic

Hi all,
after some time, I post an updated version of the spi_can driver.
Sorry for that, but I had to wait for the requested modifications
on the microcontroller's firmware to test it again.
The majork change is the GET_CFG message to query the remote
CAN microcontroller for the CAN bittiming. I hope also I have fixed
all issues from previous reviews.
- drop Patch 2/3, already applied.
- sort include headers
- match open parenthesis (globally fixed)
- add newline to dev_err() in insert_cfg_msg()
- use sizeof(*p)
- drop unused variable val in ISR
- proper return code instead of -1
- move device ids after probe/remove
- drop #ifdef CONFIG_OF (not needed anymore)
- use devm_ API
- use module_spi_driver()
- added GET_CFG message to query bit timing to the remote controller.
- implement GET_CFG message to ask the microcontroller
for bittiming consts.
- drop set_mode (never called)
- drop echo_index (never used)
- fix inconsistencies using int variable (int/u32)
- add reference to documentation in Kconfig help
- s/refTime/ref_time/
- move module parameters on the top
- use variable to get sizeof inside kzalloc/memset
- fix missing close_candev() in open entry point
- fix return values (spi_can_fill_skb_msg())
- not access skb after calling net_receive_skb()
- fix minor coding style issues
- add missing free_irq() and gpio_free() in probe when fails
- format documentation, check for lines > 80 chars (O. Hartkopp)
- patch 2/3 already aqpplied to can-next, removed from patchset
- spican.h renamed to spi_can.h
- drop further references to i.MX and HCS12, not yet cleaned
- drop CAN_DEV depend from Kconfig
- drop debug stuff via sysfs, not required in production code
- drop debug module parameter, use CAN_DEBUG_DEVICES
- drop unused bittiming constant
- chksum on as default. It could still be disabled via
DT/pdata, but not via module parameter.
- drop all references to i.MX35 and HCS12
Add documentation for SPI to CAN driver
CAN: CAN driver to support multiple CAN bus on SPI interface
Documentation/networking/spi_can.txt | 774 +++++++++++++++++
drivers/net/can/spi/Kconfig | 11 +
drivers/net/can/spi/Makefile | 1 +
drivers/net/can/spi/spi_can.c | 1506 ++++++++++++++++++++++++++++++++++
include/linux/can/platform/spi_can.h | 33 +
5 files changed, 2325 insertions(+)
create mode 100644 Documentation/networking/spi_can.txt
create mode 100644 drivers/net/can/spi/spi_can.c
create mode 100644 include/linux/can/platform/spi_can.h

--
=====================================================================
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: [phone] Fax: [phone] Email: ***@denx.de
=====================================================================
--
To unsubscribe from this list: send the line "unsubscribe linux-can" in
the body of a message to ***@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html

[Stefano Babic]

Hi Marc,

Hi all,
after some time, I post an updated version of the spi_can driver.
Sorry for that, but I had to wait for the requested modifications
on the microcontroller's firmware to test it again.
The majork change is the GET_CFG message to query the remote
CAN microcontroller for the CAN bittiming. I hope also I have fixed
all issues from previous reviews.
- drop Patch 2/3, already applied.
- sort include headers
- match open parenthesis (globally fixed)
- add newline to dev_err() in insert_cfg_msg()
- use sizeof(*p)
- drop unused variable val in ISR
- proper return code instead of -1
- move device ids after probe/remove
- drop #ifdef CONFIG_OF (not needed anymore)
- use devm_ API
- use module_spi_driver()

The driver needs to be rebased on current tree, but before doing that I
want kindly ask you which is the best way to proceed. As far as I can
see in the previous threads, I have not found any open points for V5. Do
you think there are any issue that block this driver to flow into
mainline ? Or which is in your opinion the best way to do ? Maybe should
I post it for inclusion in drivers/staging ?

Thanks,
Stefano Babic
--
=====================================================================
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: [phone] Fax: [phone] Email: ***@denx.de
=====================================================================
--
To unsubscribe from this list: send the line "unsubscribe linux-can" in
the body of a message to ***@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html