path: root/drivers/net/can/usb/ucan.c

// 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/ethtool.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>

#define UCAN_DRIVER_NAME "ucan"
#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 = BIT(0),
	UCAN_MODE_SILENT = BIT(1),
	UCAN_MODE_3_SAMPLES = BIT(2),
	UCAN_MODE_ONE_SHOT = BIT(3),
	UCAN_MODE_BERR_REPORT = BIT(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 {
	__le16 mode;         /* OR-ing any of UCAN_MODE_* */
} __packed;

struct ucan_ctl_cmd_set_bittiming {
	__le32 tq;           /* Time quanta (TQ) in nanoseconds */
	__le16 brp;          /* TQ Prescaler */
	__le16 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 {
	__le32 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;
	__le16 brp_inc;
	__le32 brp_min;
	__le32 brp_max;      /* ...can_bittiming fields */
	__le16 ctrlmodes;    /* supported control modes */
	__le16 hwfilter;     /* Number of HW filter banks */
	__le16 rxmboxes;     /* Number of receive Mailboxes */
} __packed;

struct ucan_ctl_cmd_get_protocol_version {
	__le32 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
	 *