The UCAN driver supports the microcontroller-based USB/CAN
adapters from Theobroma Systems. There are two form-factors
that run essentially the same firmware:
* Seal: standalone USB stick ( https://www.theobroma-systems.com/seal )
* Mule: integrated on the PCB of various System-on-Modules from
Theobroma Systems like the A31-µQ7 and the RK3399-Q7
( https://www.theobroma-systems.com/rk3399-q7 )
The USB wire protocol has been designed to be as generic and
hardware-indendent as possible in the hope of being useful for
implementation on other microcontrollers.
Signed-off-by: Martin Elshuber <[email protected]>
Signed-off-by: Jakob Unterwurzacher <[email protected]>
Signed-off-by: Philipp Tomsich <[email protected]>
---
Documentation/networking/can_ucan_protocol.rst | 315 +++++
Documentation/networking/index.rst | 1 +
drivers/net/can/usb/Kconfig | 10 +
drivers/net/can/usb/Makefile | 1 +
drivers/net/can/usb/ucan.c | 1587 ++++++++++++++++++++++++
5 files changed, 1914 insertions(+)
create mode 100644 Documentation/networking/can_ucan_protocol.rst
create mode 100644 drivers/net/can/usb/ucan.c
diff --git a/Documentation/networking/can_ucan_protocol.rst
b/Documentation/networking/can_ucan_protocol.rst
new file mode 100644
index 000000000000..d859b36200b4
--- /dev/null
+++ b/Documentation/networking/can_ucan_protocol.rst
@@ -0,0 +1,315 @@
+=================
+The UCAN Protocol
+=================
+
+UCAN is the protocol used by the microcontroller-based USB-CAN
+adapter that is integrated on System-on-Modules from Theobroma Systems
+and that is also available as a standalone USB stick.
+
+The UCAN protocol has been designed to be hardware-independent.
+It is modeled closely after how Linux represents CAN devices
+internally. All multi-byte integers are encoded as Little Endian.
+
+All structures mentioned in this document are defined in
+``drivers/net/can/usb/ucan.c``.
+
+USB Endpoints
+=============
+
+UCAN devices use three USB endpoints:
+
+CONTROL endpoint
+ The driver sends device management commands on this endpoint
+
+IN endpoint
+ The device sends CAN data frames and CAN error frames
+
+OUT endpoint
+ The driver sends CAN data frames on the out endpoint
+
+
+CONTROL Messages
+================
+
+UCAN devices are configured using vendor requests on the control pipe.
+
+To support multiple CAN interfaces in a single USB device all
+configuration commands target the corresponding interface in the USB
+descriptor.
+
+The driver uses ``ucan_ctrl_command_in/out`` and
+``ucan_device_request_in`` to deliver commands to the device.
+
+Setup Packet
+------------
+
+================= =====================================================
+``bmRequestType`` Direction | Vendor | (Interface or Device)
+``bRequest`` Command Number
+``wValue`` Subcommand Number (16 Bit) or 0 if not used
+``wIndex`` USB Interface Index (0 for device commands)
+``wLength`` * Host to Device - Number of bytes to transmit
+ * Device to Host - Maximum Number of bytes to
+ receive. If the device send less. Commom ZLP
+ semantics are used.
+================= =====================================================
+
+Error Handling
+--------------
+
+The device indicates failed control commands by stalling the
+pipe.
+
+Device Commands
+---------------
+
+UCAN_DEVICE_GET_FW_STRING
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+*Dev2Host; optional*
+
+Request the device firmware string.
+
+
+Interface Commands
+------------------
+
+UCAN_COMMAND_START
+~~~~~~~~~~~~~~~~~~
+
+*Host2Dev; mandatory*
+
+Bring the CAN interface up.
+
+Payload Format
+ ``ucan_ctl_payload_t.cmd_start``
+
+==== ============================
+mode or mask of ``UCAN_MODE_*``
+==== ============================
+
+UCAN_COMMAND_STOP
+~~~~~~~~~~~~~~~~~~
+
+*Host2Dev; mandatory*
+
+Stop the CAN interface
+
+Payload Format
+ *empty*
+
+UCAN_COMMAND_RESET
+~~~~~~~~~~~~~~~~~~
+
+*Host2Dev; mandatory*
+
+Reset the CAN controller (including error counters)
+
+Payload Format
+ *empty*
+
+UCAN_COMMAND_GET
+~~~~~~~~~~~~~~~~
+
+*Host2Dev; mandatory*
+
+Get Information from the Device
+
+Subcommands
+^^^^^^^^^^^
+
+UCAN_COMMAND_GET_INFO
+ Request the device information structure ``ucan_ctl_payload_t.device_info``.
+
+ See the ``device_info`` field for details, and
+ ``uapi/linux/can/netlink.h`` for an explanation of the
+ ``can_bittiming fields``.
+
+ Payload Format
+ ``ucan_ctl_payload_t.device_info``
+
+UCAN_COMMAND_GET_PROTOCOL_VERSION
+
+ Request the device protocol version
+ ``ucan_ctl_payload_t.protocol_version``. The current protocol version is 3.
+
+ Payload Format
+ ``ucan_ctl_payload_t.protocol_version``
+
+.. note:: Devices that do not implement this command use the old
+ protocol version 1
+
+UCAN_COMMAND_SET_BITTIMING
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+*Host2Dev; mandatory*
+
+Setup bittiming by sending the the structure
+``ucan_ctl_payload_t.cmd_set_bittiming`` (see ``struct bittiming`` for
+details)
+
+Payload Format
+ ``ucan_ctl_payload_t.cmd_set_bittiming``.
+
+UCAN_SLEEP/WAKE
+~~~~~~~~~~~~~~~
+
+*Host2Dev; optional*
+
+Configure sleep and wake modes. Not yet supported by the driver.
+
+UCAN_FILTER
+~~~~~~~~~~~
+
+*Host2Dev; optional*
+
+Setup hardware CAN filters. Not yet supported by the driver.
+
+Allowed interface commands
+--------------------------
+
+================== =================== ==================
+Legal Device State Command New Device State
+================== =================== ==================
+stopped SET_BITTIMING stopped
+stopped START started
+started STOP or RESET stopped
+stopped STOP or RESET stopped
+started RESTART started
+any GET *no change*
+================== =================== ==================
+
+IN Message Format
+=================
+
+A data packet on the USB IN endpoint contains one or more
+``ucan_message_in`` values. If multiple messages are batched in a USB
+data packet, the ``len`` field can be used to jump to the next
+``ucan_message_in`` value (take care to sanity-check the ``len`` value
+against the actual data size).
+
+.. _can_ucan_in_message_len:
+
+``len`` field
+-------------
+
+Each ``ucan_message_in`` must be aligned to a 4-byte boundary (relative
+to the start of the start of the data buffer). That means that there
+may be padding bytes between multiple ``ucan_message_in`` values:
+
+.. code::
+
+ +----------------------------+ < 0
+ | |
+ | struct ucan_message_in |
+ | |
+ +----------------------------+ < len
+ [padding]
+ +----------------------------+ < round_up(len, 4)
+ | |
+ | struct ucan_message_in |
+ | |
+ +----------------------------+
+ [...]
+
+``type`` field
+--------------
+
+The ``type`` field specifies the type of the message.
+
+UCAN_IN_RX
+~~~~~~~~~~
+
+``subtype``
+ zero
+
+Data received from the CAN bus (ID + payload).
+
+UCAN_IN_TX_COMPLETE
+~~~~~~~~~~~~~~~~~~~
+
+``subtype``
+ zero
+
+The CAN device has sent a message to the CAN bus. It answers with a
+set of echo-ids from previous UCAN_OUT_TX messages
+
+Flow Control
+------------
+
+When receiving CAN messages there is no flow control on the USB
+buffer. The driver has to handle inbound message quickly enough to
+avoid drops. I case the device buffer overflow the condition is
+reported by sending corresponding error frames (see
+:ref:`can_ucan_error_handling`)
+
+
+OUT Message Format
+==================
+
+A data packet on the USB OUT endpoint contains one or more ``struct
+ucan_message_out`` values. If multiple messages are batched into one
+data packet, the device uses the ``len`` field to jump to the next
+ucan_message_out value. Each ucan_message_out must be aligned to 4
+bytes (relative to the start of the data buffer). The mechanism is
+same as described in :ref:`can_ucan_in_message_len`.
+
+.. code::
+
+ +----------------------------+ < 0
+ | |
+ | struct ucan_message_out |
+ | |
+ +----------------------------+ < len
+ [padding]
+ +----------------------------+ < round_up(len, 4)
+ | |
+ | struct ucan_message_out |
+ | |
+ +----------------------------+
+ [...]
+
+``type`` field
+--------------
+
+In protocol version 3 only ``UCAN_OUT_TX`` is defined, others are used
+only by legacy devices (protocol version 1).
+
+UCAN_OUT_TX
+~~~~~~~~~~~
+``subtype``
+ echo id to be replied within a CAN_IN_TX_COMPLETE message
+
+Transmit a CAN frame. (parameters: ``id``, ``data``)
+
+Flow Control
+------------
+
+When the device outbound buffers are full it starts sending *NAKs* on
+the *OUT* pipe until more buffers are available. The driver stops the
+queue when a certain threshold of out packets are incomplete.
+
+.. _can_ucan_error_handling:
+
+CAN Error Handling
+==================
+
+If error reporting is turned on the device encodes errors into CAN
+error frames (see ``uapi/linux/can/error.h``) and sends it using the
+IN endpoint. The driver updates its error statistics and forwards
+it.
+
+Although UCAN devices can suppress error frames completely, in Linux
+the driver is always interested. Hence, the device is always started with
+the ``UCAN_MODE_BERR_REPORT`` set. Filtering those messages for the
+user space is done by the driver.
+
+Example Conversation
+====================
+
+#) Device is connected to USB
+#) Host sends command ``UCAN_COMMAND_RESET``, subcmd 0
+#) Host sends command ``UCAN_COMMAND_GET``, subcmd ``UCAN_COMMAND_GET_INFO``
+#) Device sends ``UCAN_IN_DEVICE_INFO``
+#) Host sends command ``UCAN_OUT_SET_BITTIMING``
+#) Host sends command ``UCAN_COMMAND_START``, subcmd 0, mode
``UCAN_MODE_BERR_REPORT``
diff --git a/Documentation/networking/index.rst
b/Documentation/networking/index.rst
index 90966c2692d8..18903968cebf 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -8,6 +8,7 @@ Contents:
batman-adv
can
+ can_ucan_protocol
kapi
z8530book
msg_zerocopy
diff --git a/drivers/net/can/usb/Kconfig b/drivers/net/can/usb/Kconfig
index c36f4bdcbf4f..490cdce1f1da 100644
--- a/drivers/net/can/usb/Kconfig
+++ b/drivers/net/can/usb/Kconfig
@@ -89,4 +89,14 @@ config CAN_MCBA_USB
This driver supports the CAN BUS Analyzer interface
from Microchip (http://www.microchip.com/development-tools/).
+config CAN_UCAN
+ tristate "Theobroma Systems UCAN interface"
+ ---help---
+ This driver supports the Theobroma Systems
+ UCAN USB-CAN interface.
+
+ UCAN is an microcontroller-based USB-CAN interface that
+ is integrated on System-on-Modules made by Theobroma Systems
+ (https://www.theobroma-systems.com/som-products).
+
endmenu
diff --git a/drivers/net/can/usb/Makefile b/drivers/net/can/usb/Makefile
index 49ac7b99ba32..4176e8358232 100644
--- a/drivers/net/can/usb/Makefile
+++ b/drivers/net/can/usb/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_CAN_KVASER_USB) += kvaser_usb.o
obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
obj-$(CONFIG_CAN_8DEV_USB) += usb_8dev.o
obj-$(CONFIG_CAN_MCBA_USB) += mcba_usb.o
+obj-$(CONFIG_CAN_UCAN) += ucan.o
diff --git a/drivers/net/can/usb/ucan.c b/drivers/net/can/usb/ucan.c
new file mode 100644
index 000000000000..61348e8c4747
--- /dev/null
+++ b/drivers/net/can/usb/ucan.c
@@ -0,0 +1,1587 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Driver for Theobroma Systems UCAN devices Protocol Version 3
+ *
+ * Copyright (C) 2018 Theobroma Systems Design und Consulting GmbH
+ *
+ *
+ * General Description:
+ *
+ * The USB Device uses three Endpoints:
+ *
+ * CONTROL Endpoint: Is used the setup the device (start, stop,
+ * info, configure).
+ *
+ * IN Endpoint: The device sends CAN Frame Messages and Device
+ * Information using the IN endpoint.
+ *
+ * OUT Endpoint: The driver sends configuration requests, and CAN
+ * Frames on the out endpoint.
+ *
+ * Error Handling:
+ *
+ * If error reporting is turned on the device encodes error into CAN
+ * error frames (see uapi/linux/can/error.h) and sends it using the
+ * IN Endpoint. The driver updates statistics and forward it.
+ */
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/signal.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+#define UCAN_MAX_RX_URBS 8
+/* the CAN controller needs a while to enable/disable the bus */
+#define UCAN_USB_CTL_PIPE_TIMEOUT 1000
+/* this driver currently supports protocol version 3 only */
+#define UCAN_PROTOCOL_VERSION_MIN 3
+#define UCAN_PROTOCOL_VERSION_MAX 3
+
+/* UCAN Message Definitions --------------------------------------------
+ *
+ * ucan_message_out_t and ucan_message_in_t define the messages
+ * transmitted on the OUT and IN endpoint.
+ *
+ * Multibyte fields are transmitted with little endianness
+ *
+ * INTR Endpoint: a single uint32_t storing the current space in the fifo
+ *
+ * OUT Endpoint: single message of type ucan_message_out_t is
+ * transmitted on the out endpoint
+ *
+ * IN Endpoint: multiple messages ucan_message_in_t concateted in
+ * the following way:
+ *
+ * m[n].len <=> the length if message n(including the header in bytes)
+ * m[n] is is aligned to a 4 byte boundary, hence
+ * offset(m[0]) := 0;
+ * offset(m[n+1]) := offset(m[n]) + (m[n].len + 3) & 3
+ *
+ * this implies that
+ * offset(m[n]) % 4 <=> 0
+ */
+
+/* Device Global Commands */
+enum {
+ UCAN_DEVICE_GET_FW_STRING = 0,
+};
+
+/* UCAN Commands */
+enum {
+ /* start the can transceiver - val defines the operation mode */
+ UCAN_COMMAND_START = 0,
+ /* cancel pending transmissions and stop the can transceiver */
+ UCAN_COMMAND_STOP = 1,
+ /* send can transceiver into low-power sleep mode */
+ UCAN_COMMAND_SLEEP = 2,
+ /* wake up can transceiver from low-power sleep mode */
+ UCAN_COMMAND_WAKEUP = 3,
+ /* reset the can transceiver */
+ UCAN_COMMAND_RESET = 4,
+ /* get piece of info from the can transceiver - subcmd defines what
+ * piece
+ */
+ UCAN_COMMAND_GET = 5,
+ /* clear or disable hardware filter - subcmd defines which of the two */
+ UCAN_COMMAND_FILTER = 6,
+ /* Setup bittiming */
+ UCAN_COMMAND_SET_BITTIMING = 7,
+ /* recover from bus-off state */
+ UCAN_COMMAND_RESTART = 8,
+};
+
+/* UCAN_COMMAND_START and UCAN_COMMAND_GET_INFO operation modes (bitmap).
+ * Undefined bits must be set to 0.
+ */
+enum {
+ UCAN_MODE_LOOPBACK = (1 << 0),
+ UCAN_MODE_SILENT = (1 << 1),
+ UCAN_MODE_3_SAMPLES = (1 << 2),
+ UCAN_MODE_ONE_SHOT = (1 << 3),
+ UCAN_MODE_BERR_REPORT = (1 << 4),
+};
+
+/* UCAN_COMMAND_GET subcommands */
+enum {
+ UCAN_COMMAND_GET_INFO = 0,
+ UCAN_COMMAND_GET_PROTOCOL_VERSION = 1,
+};
+
+/* UCAN_COMMAND_FILTER subcommands */
+enum {
+ UCAN_FILTER_CLEAR = 0,
+ UCAN_FILTER_DISABLE = 1,
+ UCAN_FILTER_ENABLE = 2,
+};
+
+/* OUT endpoint message types */
+enum {
+ UCAN_OUT_TX = 2, /* transmit a CAN frame */
+};
+
+/* IN endpoint message types */
+enum {
+ UCAN_IN_TX_COMPLETE = 1, /* CAN frame transmission completed */
+ UCAN_IN_RX = 2, /* CAN frame received */
+};
+
+struct ucan_ctl_cmd_start {
+ u16 mode; /* oring any of UCAN_MODE_* */
+} __packed;
+
+struct ucan_ctl_cmd_set_bittiming {
+ u32 tq; /* Time quanta (TQ) in nanoseconds */
+ u16 brp; /* TQ Prescaler */
+ u16 sample_point; /* Samplepoint on tenth percent */
+ u8 prop_seg; /* Propagation segment in TQs */
+ u8 phase_seg1; /* Phase buffer segment 1 in TQs */
+ u8 phase_seg2; /* Phase buffer segment 2 in TQs */
+ u8 sjw; /* Synchronisation jump width in TQs */
+} __packed;
+
+struct ucan_ctl_cmd_device_info {
+ u32 freq; /* Clock Frequency for tq generation */
+ u8 tx_fifo; /* Size of the transmission fifo */
+ u8 sjw_max; /* can_bittiming fields... */
+ u8 tseg1_min;
+ u8 tseg1_max;
+ u8 tseg2_min;
+ u8 tseg2_max;
+ u16 brp_inc;
+ u32 brp_min;
+ u32 brp_max; /* ...can_bittiming fields */
+ u16 ctrlmodes; /* supported control modes */
+ u16 hwfilter; /* Number of HW filter banks */
+ u16 rxmboxes; /* Number of receive Mailboxes */
+} __packed;
+
+struct ucan_ctl_cmd_get_protocol_version {
+ u32 version;
+} __packed;
+
+union ucan_ctl_payload {
+ /***************************************************
+ * Setup Bittiming
+ * bmRequest == UCAN_COMMAND_START
+ ***************************************************/
+ struct ucan_ctl_cmd_start cmd_start;
+ /***************************************************
+ * Setup Bittiming
+ * bmRequest == UCAN_COMMAND_SET_BITTIMING
+ ***************************************************/
+ struct ucan_ctl_cmd_set_bittiming cmd_set_bittiming;
+ /***************************************************
+ * Get Device Information
+ * bmRequest == UCAN_COMMAND_GET; wValue = UCAN_COMMAND_GET_INFO
+ ***************************************************/
+ struct ucan_ctl_cmd_device_info cmd_get_device_info;
+ /***************************************************
+ * Get Protocol Version
+ * bmRequest == UCAN_COMMAND_GET;
+ * wValue = UCAN_COMMAND_GET_PROTOCOL_VERSION
+ ***************************************************/
+ struct ucan_ctl_cmd_get_protocol_version cmd_get_protocol_version;
+
+ u8 raw[128];
+} __packed;
+
+enum {
+ UCAN_TX_COMPLETE_SUCCESS = (1 << 0),
+};
+
+/* Transmission Complete within ucan_message_in */
+struct ucan_tx_complete_entry_t {
+ u8 echo_id;
+ u8 flags;
+} __packed __aligned(0x2);
+
+/* CAN Data message format within ucan_message_in/out */
+struct ucan_can_msg {
+ /* note DLC is computed by
+ * msg.len - sizeof (msg.len)
+ * - sizeof (msg.type)
+ * - sizeof (msg.can_msg.id)
+ */
+ u32 id;
+
+ union {
+ u8 data[CAN_MAX_DLEN]; /* Data of CAN frames */
+ u8 dlc; /* RTR dlc */
+ };
+} __packed;
+
+/* OUT Endpoint, outbound messages */
+struct ucan_message_out {
+ u16 len; /* Length of the content include header */
+ u8 type; /* UCAN_OUT_TX and friends */
+ u8 subtype; /* command sub type */
+ union {
+ /***************************************************
+ * Transmit CAN frame
+ * (type == UCAN_TX) && ((msg.can_msg.id & CAN_RTR_FLAG) == 0)
+ * subtype stores the echo id
+ ***************************************************/
+ struct ucan_can_msg can_msg;
+ } msg;
+} __packed __aligned(0x4);
+
+/* IN Endpoint, inbound messages */
+struct ucan_message_in {
+ u16 len; /* Length of the content include header */
+ u8 type; /* UCAN_IN_RX and friends */
+ u8 subtype; /* command sub type */
+
+ union {
+ /***************************************************
+ * CAN Frame received
+ * (type == UCAN_IN_RX)
+ * && ((msg.can_msg.id & CAN_RTR_FLAG) == 0)
+ ***************************************************/
+ struct ucan_can_msg can_msg;
+
+ /***************************************************
+ * CAN transmission complete
+ * (type == UCAN_IN_TX_COMPLETE)
+ ***************************************************/
+ struct ucan_tx_complete_entry_t can_tx_complete_msg[0];
+
+ } __aligned(0x4) msg;
+} __packed;
+
+/* Macros to calculate message lengths */
+#define UCAN_OUT_HDR_SIZE offsetof(struct ucan_message_out, msg)
+
+#define UCAN_IN_HDR_SIZE offsetof(struct ucan_message_in, msg)
+#define UCAN_IN_LEN(member) (UCAN_OUT_HDR_SIZE + sizeof(member))
+
+struct ucan_priv;
+
+/* Context Information for transmission URBs */
+struct ucan_urb_context {
+ struct ucan_priv *up;
+ u32 echo_index;
+ u8 dlc;
+ atomic_t allocated;
+};
+
+/* Information reported by the USB device */
+struct ucan_device_info {
+ struct can_bittiming_const bittiming_const;
+ u8 tx_fifo;
+};
+
+/* Driver private data */
+struct ucan_priv {
+ struct can_priv can; /* must be the first member */
+
+ u8 intf_index;
+ struct usb_device *udev;
+ struct usb_interface *intf;
+ struct net_device *netdev;
+
+ struct usb_endpoint_descriptor *out_ep;
+ struct usb_endpoint_descriptor *in_ep;
+
+ struct usb_anchor rx_urbs;
+ struct usb_anchor tx_urbs;
+
+ union ucan_ctl_payload *ctl_msg_buffer;
+ struct ucan_device_info device_info;
+
+ atomic_t available_tx_urbs;
+ struct ucan_urb_context *tx_contexts;
+};
+
+static u8 ucan_compute_dlc(u16 len, struct ucan_can_msg *msg)
+{
+ u16 res = 0;
+
+ if (msg->id & CAN_RTR_FLAG)
+ res = msg->dlc;
+ else
+ res = len - (UCAN_IN_HDR_SIZE + sizeof(msg->id));
+
+ if (res > CAN_MAX_DLEN)
+ return -1;
+
+ return res;
+}
+
+static void ucan_release_contexts(struct ucan_priv *up)
+{
+ if (!up->tx_contexts)
+ return;
+
+ atomic_set(&up->available_tx_urbs, 0);
+
+ kfree(up->tx_contexts);
+ up->tx_contexts = NULL;
+}
+
+static int ucan_allocate_contexts(struct ucan_priv *up)
+{
+ int i;
+
+ /* release contexts if any */
+ ucan_release_contexts(up);
+
+ up->tx_contexts = kmalloc_array(up->device_info.tx_fifo,
+ sizeof(*up->tx_contexts),
+ GFP_KERNEL);
+ if (!up->tx_contexts) {
+ dev_err(&up->udev->dev, "Not enough memory to allocate tx
contexts\n");
+ return -ENOMEM;
+ }
+
+ memset(up->tx_contexts, 0,
+ sizeof(*up->tx_contexts) * up->device_info.tx_fifo);
+ for (i = 0; i < up->device_info.tx_fifo; i++) {
+ atomic_set(&up->tx_contexts[i].allocated, 0);
+ up->tx_contexts[i].up = up;
+ up->tx_contexts[i].echo_index = i;
+ }
+
+ atomic_set(&up->available_tx_urbs, up->device_info.tx_fifo);
+
+ return 0;
+}
+
+static struct ucan_urb_context *ucan_allocate_context(struct ucan_priv *up)
+{
+ int i, allocated, avail;
+
+ if (!up->tx_contexts)
+ return NULL;
+
+ for (i = 0; i < up->device_info.tx_fifo; i++) {
+ allocated = atomic_cmpxchg(&up->tx_contexts[i].allocated, 0, 1);
+ if (allocated == 0) {
+ avail = atomic_sub_return(1, &up->available_tx_urbs);
+ if (avail == 0)
+ netif_stop_queue(up->netdev);
+ return &up->tx_contexts[i];
+ }
+ }
+ return NULL;
+}
+
+static void ucan_release_context(struct ucan_priv *up,
+ struct ucan_urb_context *ctx)
+{
+ WARN_ON_ONCE(!up->tx_contexts);
+ if (!up->tx_contexts)
+ return;
+
+ if (atomic_cmpxchg(&ctx->allocated, 1, 0) == 0) {
+ dev_warn(&up->udev->dev,
+ "context %p (#%ld) was not allocated\n",
+ ctx, ctx - up->tx_contexts);
+ } else {
+ atomic_inc(&up->available_tx_urbs);
+ netif_wake_queue(up->netdev);
+ }
+}
+
+static int ucan_ctrl_command_out(struct ucan_priv *up,
+ u8 cmd,
+ u16 subcmd,
+ size_t datalen)
+{
+ if (datalen > sizeof(union ucan_ctl_payload))
+ return -ENOMEM;
+
+ return usb_control_msg(up->udev,
+ usb_sndctrlpipe(up->udev, 0),
+ cmd,
+ USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
+ cpu_to_le16(subcmd),
+ up->intf_index,
+ up->ctl_msg_buffer,
+ datalen,
+ UCAN_USB_CTL_PIPE_TIMEOUT);
+}
+
+static int ucan_device_request_in(struct ucan_priv *up,
+ u8 cmd,
+ u16 subcmd,
+ size_t datalen)
+{
+ if (datalen > sizeof(union ucan_ctl_payload))
+ return -ENOMEM;
+
+ return usb_control_msg(up->udev,
+ usb_rcvctrlpipe(up->udev, 0),
+ cmd,
+ USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+ cpu_to_le16(subcmd),
+ 0,
+ up->ctl_msg_buffer,
+ datalen,
+ UCAN_USB_CTL_PIPE_TIMEOUT);
+}
+
+/* Parse the device information structure reported by the device and
+ * setup private variables accordingly
+ */
+static void ucan_parse_device_info(struct ucan_priv *up,
+ struct ucan_ctl_cmd_device_info
+ *ctl_cmd_device_info)
+{
+ struct can_bittiming_const *bittiming =
+ &up->device_info.bittiming_const;
+ u16 ctrlmodes;
+
+ /* store the data */
+ up->can.clock.freq = le32_to_cpu(ctl_cmd_device_info->freq);
+ up->device_info.tx_fifo = ctl_cmd_device_info->tx_fifo;
+ strcpy(bittiming->name, "ucan");
+ bittiming->tseg1_min = ctl_cmd_device_info->tseg1_min;
+ bittiming->tseg1_max = ctl_cmd_device_info->tseg1_max;
+ bittiming->tseg2_min = ctl_cmd_device_info->tseg2_min;
+ bittiming->tseg2_max = ctl_cmd_device_info->tseg2_max;
+ bittiming->sjw_max = ctl_cmd_device_info->sjw_max;
+ bittiming->brp_min = le32_to_cpu(ctl_cmd_device_info->brp_min);
+ bittiming->brp_max = le32_to_cpu(ctl_cmd_device_info->brp_max);
+ bittiming->brp_inc = le16_to_cpu(ctl_cmd_device_info->brp_inc);
+
+ ctrlmodes = le16_to_cpu(ctl_cmd_device_info->ctrlmodes);
+
+ up->can.ctrlmode_supported = 0;
+
+ if (ctrlmodes & UCAN_MODE_LOOPBACK)
+ up->can.ctrlmode_supported |= CAN_CTRLMODE_LOOPBACK;
+ if (ctrlmodes & UCAN_MODE_SILENT)
+ up->can.ctrlmode_supported |= CAN_CTRLMODE_LISTENONLY;
+ if (ctrlmodes & UCAN_MODE_3_SAMPLES)
+ up->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
+ if (ctrlmodes & UCAN_MODE_ONE_SHOT)
+ up->can.ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT;
+ if (ctrlmodes & UCAN_MODE_BERR_REPORT)
+ up->can.ctrlmode_supported |= CAN_CTRLMODE_BERR_REPORTING;
+}
+
+/* Handle a CAN error frame that we have received from the device */
+static void ucan_handle_error_frame(struct ucan_priv *up,
+ struct ucan_message_in *m,
+ u32 canid)
+{
+ enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
+ struct net_device_stats *net_stats = &up->netdev->stats;
+ struct can_device_stats *can_stats = &up->can.can_stats;
+
+ if (canid & CAN_ERR_LOSTARB)
+ can_stats->arbitration_lost++;
+
+ if (canid & CAN_ERR_BUSERROR)
+ can_stats->bus_error++;
+
+ if (canid & CAN_ERR_ACK)
+ net_stats->tx_errors++;
+
+ if (canid & CAN_ERR_BUSOFF)
+ new_state = CAN_STATE_BUS_OFF;
+
+ /* controller problems, details in data[1] */
+ if (canid & CAN_ERR_CRTL) {
+ u8 d1 = m->msg.can_msg.data[1];
+
+ if (d1 & (CAN_ERR_CRTL_RX_PASSIVE | CAN_ERR_CRTL_TX_PASSIVE))
+ new_state = max(new_state, (enum can_state)
+ CAN_STATE_ERROR_PASSIVE);
+
+ if (d1 & (CAN_ERR_CRTL_RX_WARNING | CAN_ERR_CRTL_TX_WARNING))
+ new_state = max(new_state, (enum can_state)
+ CAN_STATE_ERROR_WARNING);
+
+ if (d1 & CAN_ERR_CRTL_RX_OVERFLOW)
+ net_stats->rx_over_errors++;
+ }
+
+ /* protocol error, details in data[2] */
+ if (canid & CAN_ERR_PROT) {
+ u8 d2 = m->msg.can_msg.data[2];
+
+ if (d2 & CAN_ERR_PROT_TX)
+ net_stats->tx_errors++;
+ else
+ net_stats->rx_errors++;
+ }
+
+ /* we switched into a better state */
+ if (up->can.state >= new_state) {
+ up->can.state = new_state;
+ return;
+ }
+
+ /* we switched into a worse state */
+ up->can.state = new_state;
+ switch (new_state) {
+ case CAN_STATE_BUS_OFF:
+ can_stats->bus_off++;
+ can_bus_off(up->netdev);
+ netdev_info(up->netdev,
+ "link has gone into BUS-OFF state\n");
+ break;
+ case CAN_STATE_ERROR_PASSIVE:
+ can_stats->error_passive++;
+ break;
+ case CAN_STATE_ERROR_WARNING:
+ can_stats->error_warning++;
+ break;
+ default:
+ break;
+ }
+}
+
+/* Callback on reception of a can frame via the IN endpoint
+ *
+ * This function allocates an skb and transferres it to the Linux
+ * network stack
+ */
+static void ucan_rx_can_msg(struct ucan_priv *up, struct ucan_message_in *m)
+{
+ int len;
+ u32 canid;
+ struct can_frame *cf;
+ struct sk_buff *skb;
+ struct net_device_stats *stats = &up->netdev->stats;
+
+ /* get the contents of the length field */
+ len = le16_to_cpu(m->len);
+
+ /* check sanity */
+ if (len < UCAN_IN_HDR_SIZE + sizeof(m->msg.can_msg.id)) {
+ dev_warn(&up->udev->dev, "invalid input message len\n");
+ return;
+ }
+
+ /* handle error frames */
+ canid = le32_to_cpu(m->msg.can_msg.id);
+ if (canid & CAN_ERR_FLAG) {
+ ucan_handle_error_frame(up, m, canid);
+ /* drop frame if berr-reporting is off */
+ if (!(up->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING))
+ return;
+ }
