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Diffstat (limited to 'drivers/net/can/can327.c')
-rw-r--r--drivers/net/can/can327.c1142
1 files changed, 1142 insertions, 0 deletions
diff --git a/drivers/net/can/can327.c b/drivers/net/can/can327.c
new file mode 100644
index 0000000000..24af639610
--- /dev/null
+++ b/drivers/net/can/can327.c
@@ -0,0 +1,1142 @@
+// SPDX-License-Identifier: GPL-2.0
+/* ELM327 based CAN interface driver (tty line discipline)
+ *
+ * This driver started as a derivative of linux/drivers/net/can/slcan.c
+ * and my thanks go to the original authors for their inspiration.
+ *
+ * can327.c Author : Max Staudt <max-linux@enpas.org>
+ * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net>
+ * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk>
+ * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include <linux/bitops.h>
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/lockdep.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/tty.h>
+#include <linux/tty_ldisc.h>
+#include <linux/workqueue.h>
+
+#include <uapi/linux/tty.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/rx-offload.h>
+
+#define CAN327_NAPI_WEIGHT 4
+
+#define CAN327_SIZE_TXBUF 32
+#define CAN327_SIZE_RXBUF 1024
+
+#define CAN327_CAN_CONFIG_SEND_SFF 0x8000
+#define CAN327_CAN_CONFIG_VARIABLE_DLC 0x4000
+#define CAN327_CAN_CONFIG_RECV_BOTH_SFF_EFF 0x2000
+#define CAN327_CAN_CONFIG_BAUDRATE_MULT_8_7 0x1000
+
+#define CAN327_DUMMY_CHAR 'y'
+#define CAN327_DUMMY_STRING "y"
+#define CAN327_READY_CHAR '>'
+
+/* Bits in elm->cmds_todo */
+enum can327_tx_do {
+ CAN327_TX_DO_CAN_DATA = 0,
+ CAN327_TX_DO_CANID_11BIT,
+ CAN327_TX_DO_CANID_29BIT_LOW,
+ CAN327_TX_DO_CANID_29BIT_HIGH,
+ CAN327_TX_DO_CAN_CONFIG_PART2,
+ CAN327_TX_DO_CAN_CONFIG,
+ CAN327_TX_DO_RESPONSES,
+ CAN327_TX_DO_SILENT_MONITOR,
+ CAN327_TX_DO_INIT,
+};
+
+struct can327 {
+ /* This must be the first member when using alloc_candev() */
+ struct can_priv can;
+
+ struct can_rx_offload offload;
+
+ /* TTY buffers */
+ u8 txbuf[CAN327_SIZE_TXBUF];
+ u8 rxbuf[CAN327_SIZE_RXBUF];
+
+ /* Per-channel lock */
+ spinlock_t lock;
+
+ /* TTY and netdev devices that we're bridging */
+ struct tty_struct *tty;
+ struct net_device *dev;
+
+ /* TTY buffer accounting */
+ struct work_struct tx_work; /* Flushes TTY TX buffer */
+ u8 *txhead; /* Next TX byte */
+ size_t txleft; /* Bytes left to TX */
+ int rxfill; /* Bytes already RX'd in buffer */
+
+ /* State machine */
+ enum {
+ CAN327_STATE_NOTINIT = 0,
+ CAN327_STATE_GETDUMMYCHAR,
+ CAN327_STATE_GETPROMPT,
+ CAN327_STATE_RECEIVING,
+ } state;
+
+ /* Things we have yet to send */
+ char **next_init_cmd;
+ unsigned long cmds_todo;
+
+ /* The CAN frame and config the ELM327 is sending/using,
+ * or will send/use after finishing all cmds_todo
+ */
+ struct can_frame can_frame_to_send;
+ u16 can_config;
+ u8 can_bitrate_divisor;
+
+ /* Parser state */
+ bool drop_next_line;
+
+ /* Stop the channel on UART side hardware failure, e.g. stray
+ * characters or neverending lines. This may be caused by bad
+ * UART wiring, a bad ELM327, a bad UART bridge...
+ * Once this is true, nothing will be sent to the TTY.
+ */
+ bool uart_side_failure;
+};
+
+static inline void can327_uart_side_failure(struct can327 *elm);
+
+static void can327_send(struct can327 *elm, const void *buf, size_t len)
+{
+ int written;
+
+ lockdep_assert_held(&elm->lock);
+
+ if (elm->uart_side_failure)
+ return;
+
+ memcpy(elm->txbuf, buf, len);
+
+ /* Order of next two lines is *very* important.
+ * When we are sending a little amount of data,
+ * the transfer may be completed inside the ops->write()
+ * routine, because it's running with interrupts enabled.
+ * In this case we *never* got WRITE_WAKEUP event,
+ * if we did not request it before write operation.
+ * 14 Oct 1994 Dmitry Gorodchanin.
+ */
+ set_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+ written = elm->tty->ops->write(elm->tty, elm->txbuf, len);
+ if (written < 0) {
+ netdev_err(elm->dev, "Failed to write to tty %s.\n",
+ elm->tty->name);
+ can327_uart_side_failure(elm);
+ return;
+ }
+
+ elm->txleft = len - written;
+ elm->txhead = elm->txbuf + written;
+}
+
+/* Take the ELM327 out of almost any state and back into command mode.
+ * We send CAN327_DUMMY_CHAR which will either abort any running
+ * operation, or be echoed back to us in case we're already in command
+ * mode.
+ */
+static void can327_kick_into_cmd_mode(struct can327 *elm)
+{
+ lockdep_assert_held(&elm->lock);
+
+ if (elm->state != CAN327_STATE_GETDUMMYCHAR &&
+ elm->state != CAN327_STATE_GETPROMPT) {
+ can327_send(elm, CAN327_DUMMY_STRING, 1);
+
+ elm->state = CAN327_STATE_GETDUMMYCHAR;
+ }
+}
+
+/* Schedule a CAN frame and necessary config changes to be sent to the TTY. */
+static void can327_send_frame(struct can327 *elm, struct can_frame *frame)
+{
+ lockdep_assert_held(&elm->lock);
+
+ /* Schedule any necessary changes in ELM327's CAN configuration */
+ if (elm->can_frame_to_send.can_id != frame->can_id) {
+ /* Set the new CAN ID for transmission. */
+ if ((frame->can_id ^ elm->can_frame_to_send.can_id)
+ & CAN_EFF_FLAG) {
+ elm->can_config =
+ (frame->can_id & CAN_EFF_FLAG ? 0 : CAN327_CAN_CONFIG_SEND_SFF) |
+ CAN327_CAN_CONFIG_VARIABLE_DLC |
+ CAN327_CAN_CONFIG_RECV_BOTH_SFF_EFF |
+ elm->can_bitrate_divisor;
+
+ set_bit(CAN327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
+ }
+
+ if (frame->can_id & CAN_EFF_FLAG) {
+ clear_bit(CAN327_TX_DO_CANID_11BIT, &elm->cmds_todo);
+ set_bit(CAN327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo);
+ set_bit(CAN327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ } else {
+ set_bit(CAN327_TX_DO_CANID_11BIT, &elm->cmds_todo);
+ clear_bit(CAN327_TX_DO_CANID_29BIT_LOW,
+ &elm->cmds_todo);
+ clear_bit(CAN327_TX_DO_CANID_29BIT_HIGH,
+ &elm->cmds_todo);
+ }
+ }
+
+ /* Schedule the CAN frame itself. */
+ elm->can_frame_to_send = *frame;
+ set_bit(CAN327_TX_DO_CAN_DATA, &elm->cmds_todo);
+
+ can327_kick_into_cmd_mode(elm);
+}
+
+/* ELM327 initialisation sequence.
+ * The line length is limited by the buffer in can327_handle_prompt().
+ */
+static char *can327_init_script[] = {
+ "AT WS\r", /* v1.0: Warm Start */
+ "AT PP FF OFF\r", /* v1.0: All Programmable Parameters Off */
+ "AT M0\r", /* v1.0: Memory Off */
+ "AT AL\r", /* v1.0: Allow Long messages */
+ "AT BI\r", /* v1.0: Bypass Initialisation */
+ "AT CAF0\r", /* v1.0: CAN Auto Formatting Off */
+ "AT CFC0\r", /* v1.0: CAN Flow Control Off */
+ "AT CF 000\r", /* v1.0: Reset CAN ID Filter */
+ "AT CM 000\r", /* v1.0: Reset CAN ID Mask */
+ "AT E1\r", /* v1.0: Echo On */
+ "AT H1\r", /* v1.0: Headers On */
+ "AT L0\r", /* v1.0: Linefeeds Off */
+ "AT SH 7DF\r", /* v1.0: Set CAN sending ID to 0x7df */
+ "AT ST FF\r", /* v1.0: Set maximum Timeout for response after TX */
+ "AT AT0\r", /* v1.2: Adaptive Timing Off */
+ "AT D1\r", /* v1.3: Print DLC On */
+ "AT S1\r", /* v1.3: Spaces On */
+ "AT TP B\r", /* v1.0: Try Protocol B */
+ NULL
+};
+
+static void can327_init_device(struct can327 *elm)
+{
+ lockdep_assert_held(&elm->lock);
+
+ elm->state = CAN327_STATE_NOTINIT;
+ elm->can_frame_to_send.can_id = 0x7df; /* ELM327 HW default */
+ elm->rxfill = 0;
+ elm->drop_next_line = 0;
+
+ /* We can only set the bitrate as a fraction of 500000.
+ * The bitrates listed in can327_bitrate_const will
+ * limit the user to the right values.
+ */
+ elm->can_bitrate_divisor = 500000 / elm->can.bittiming.bitrate;
+ elm->can_config =
+ CAN327_CAN_CONFIG_SEND_SFF | CAN327_CAN_CONFIG_VARIABLE_DLC |
+ CAN327_CAN_CONFIG_RECV_BOTH_SFF_EFF | elm->can_bitrate_divisor;
+
+ /* Configure ELM327 and then start monitoring */
+ elm->next_init_cmd = &can327_init_script[0];
+ set_bit(CAN327_TX_DO_INIT, &elm->cmds_todo);
+ set_bit(CAN327_TX_DO_SILENT_MONITOR, &elm->cmds_todo);
+ set_bit(CAN327_TX_DO_RESPONSES, &elm->cmds_todo);
+ set_bit(CAN327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
+
+ can327_kick_into_cmd_mode(elm);
+}
+
+static void can327_feed_frame_to_netdev(struct can327 *elm, struct sk_buff *skb)
+{
+ lockdep_assert_held(&elm->lock);
+
+ if (!netif_running(elm->dev)) {
+ kfree_skb(skb);
+ return;
+ }
+
+ /* Queue for NAPI pickup.
+ * rx-offload will update stats and LEDs for us.
+ */
+ if (can_rx_offload_queue_tail(&elm->offload, skb))
+ elm->dev->stats.rx_fifo_errors++;
+
+ /* Wake NAPI */
+ can_rx_offload_irq_finish(&elm->offload);
+}
+
+/* Called when we're out of ideas and just want it all to end. */
+static inline void can327_uart_side_failure(struct can327 *elm)
+{
+ struct can_frame *frame;
+ struct sk_buff *skb;
+
+ lockdep_assert_held(&elm->lock);
+
+ elm->uart_side_failure = true;
+
+ clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+
+ elm->can.can_stats.bus_off++;
+ netif_stop_queue(elm->dev);
+ elm->can.state = CAN_STATE_BUS_OFF;
+ can_bus_off(elm->dev);
+
+ netdev_err(elm->dev,
+ "ELM327 misbehaved. Blocking further communication.\n");
+
+ skb = alloc_can_err_skb(elm->dev, &frame);
+ if (!skb)
+ return;
+
+ frame->can_id |= CAN_ERR_BUSOFF;
+ can327_feed_frame_to_netdev(elm, skb);
+}
+
+/* Compares a byte buffer (non-NUL terminated) to the payload part of
+ * a string, and returns true iff the buffer (content *and* length) is
+ * exactly that string, without the terminating NUL byte.
+ *
+ * Example: If reference is "BUS ERROR", then this returns true iff nbytes == 9
+ * and !memcmp(buf, "BUS ERROR", 9).
+ *
+ * The reason to use strings is so we can easily include them in the C
+ * code, and to avoid hardcoding lengths.
+ */
+static inline bool can327_rxbuf_cmp(const u8 *buf, size_t nbytes,
+ const char *reference)
+{
+ size_t ref_len = strlen(reference);
+
+ return (nbytes == ref_len) && !memcmp(buf, reference, ref_len);
+}
+
+static void can327_parse_error(struct can327 *elm, size_t len)
+{
+ struct can_frame *frame;
+ struct sk_buff *skb;
+
+ lockdep_assert_held(&elm->lock);
+
+ skb = alloc_can_err_skb(elm->dev, &frame);
+ if (!skb)
+ /* It's okay to return here:
+ * The outer parsing loop will drop this UART buffer.
+ */
+ return;
+
+ /* Filter possible error messages based on length of RX'd line */
+ if (can327_rxbuf_cmp(elm->rxbuf, len, "UNABLE TO CONNECT")) {
+ netdev_err(elm->dev,
+ "ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
+ } else if (can327_rxbuf_cmp(elm->rxbuf, len, "BUFFER FULL")) {
+ /* This will only happen if the last data line was complete.
+ * Otherwise, can327_parse_frame() will heuristically
+ * emit this kind of error frame instead.
+ */
+ frame->can_id |= CAN_ERR_CRTL;
+ frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+ } else if (can327_rxbuf_cmp(elm->rxbuf, len, "BUS ERROR")) {
+ frame->can_id |= CAN_ERR_BUSERROR;
+ } else if (can327_rxbuf_cmp(elm->rxbuf, len, "CAN ERROR")) {
+ frame->can_id |= CAN_ERR_PROT;
+ } else if (can327_rxbuf_cmp(elm->rxbuf, len, "<RX ERROR")) {
+ frame->can_id |= CAN_ERR_PROT;
+ } else if (can327_rxbuf_cmp(elm->rxbuf, len, "BUS BUSY")) {
+ frame->can_id |= CAN_ERR_PROT;
+ frame->data[2] = CAN_ERR_PROT_OVERLOAD;
+ } else if (can327_rxbuf_cmp(elm->rxbuf, len, "FB ERROR")) {
+ frame->can_id |= CAN_ERR_PROT;
+ frame->data[2] = CAN_ERR_PROT_TX;
+ } else if (len == 5 && !memcmp(elm->rxbuf, "ERR", 3)) {
+ /* ERR is followed by two digits, hence line length 5 */
+ netdev_err(elm->dev, "ELM327 reported an ERR%c%c. Please power it off and on again.\n",
+ elm->rxbuf[3], elm->rxbuf[4]);
+ frame->can_id |= CAN_ERR_CRTL;
+ } else {
+ /* Something else has happened.
+ * Maybe garbage on the UART line.
+ * Emit a generic error frame.
+ */
+ }
+
+ can327_feed_frame_to_netdev(elm, skb);
+}
+
+/* Parse CAN frames coming as ASCII from ELM327.
+ * They can be of various formats:
+ *
+ * 29-bit ID (EFF): 12 34 56 78 D PL PL PL PL PL PL PL PL
+ * 11-bit ID (!EFF): 123 D PL PL PL PL PL PL PL PL
+ *
+ * where D = DLC, PL = payload byte
+ *
+ * Instead of a payload, RTR indicates a remote request.
+ *
+ * We will use the spaces and line length to guess the format.
+ */
+static int can327_parse_frame(struct can327 *elm, size_t len)
+{
+ struct can_frame *frame;
+ struct sk_buff *skb;
+ int hexlen;
+ int datastart;
+ int i;
+
+ lockdep_assert_held(&elm->lock);
+
+ skb = alloc_can_skb(elm->dev, &frame);
+ if (!skb)
+ return -ENOMEM;
+
+ /* Find first non-hex and non-space character:
+ * - In the simplest case, there is none.
+ * - For RTR frames, 'R' is the first non-hex character.
+ * - An error message may replace the end of the data line.
+ */
+ for (hexlen = 0; hexlen <= len; hexlen++) {
+ if (hex_to_bin(elm->rxbuf[hexlen]) < 0 &&
+ elm->rxbuf[hexlen] != ' ') {
+ break;
+ }
+ }
+
+ /* Sanity check whether the line is really a clean hexdump,
+ * or terminated by an error message, or contains garbage.
+ */
+ if (hexlen < len && !isdigit(elm->rxbuf[hexlen]) &&
+ !isupper(elm->rxbuf[hexlen]) && '<' != elm->rxbuf[hexlen] &&
+ ' ' != elm->rxbuf[hexlen]) {
+ /* The line is likely garbled anyway, so bail.
+ * The main code will restart listening.
+ */
+ kfree_skb(skb);
+ return -ENODATA;
+ }
+
+ /* Use spaces in CAN ID to distinguish 29 or 11 bit address length.
+ * No out-of-bounds access:
+ * We use the fact that we can always read from elm->rxbuf.
+ */
+ if (elm->rxbuf[2] == ' ' && elm->rxbuf[5] == ' ' &&
+ elm->rxbuf[8] == ' ' && elm->rxbuf[11] == ' ' &&
+ elm->rxbuf[13] == ' ') {
+ frame->can_id = CAN_EFF_FLAG;
+ datastart = 14;
+ } else if (elm->rxbuf[3] == ' ' && elm->rxbuf[5] == ' ') {
+ datastart = 6;
+ } else {
+ /* This is not a well-formatted data line.
+ * Assume it's an error message.
+ */
+ kfree_skb(skb);
+ return -ENODATA;
+ }
+
+ if (hexlen < datastart) {
+ /* The line is too short to be a valid frame hex dump.
+ * Something interrupted the hex dump or it is invalid.
+ */
+ kfree_skb(skb);
+ return -ENODATA;
+ }
+
+ /* From here on all chars up to buf[hexlen] are hex or spaces,
+ * at well-defined offsets.
+ */
+
+ /* Read CAN data length */
+ frame->len = (hex_to_bin(elm->rxbuf[datastart - 2]) << 0);
+
+ /* Read CAN ID */
+ if (frame->can_id & CAN_EFF_FLAG) {
+ frame->can_id |= (hex_to_bin(elm->rxbuf[0]) << 28) |
+ (hex_to_bin(elm->rxbuf[1]) << 24) |
+ (hex_to_bin(elm->rxbuf[3]) << 20) |
+ (hex_to_bin(elm->rxbuf[4]) << 16) |
+ (hex_to_bin(elm->rxbuf[6]) << 12) |
+ (hex_to_bin(elm->rxbuf[7]) << 8) |
+ (hex_to_bin(elm->rxbuf[9]) << 4) |
+ (hex_to_bin(elm->rxbuf[10]) << 0);
+ } else {
+ frame->can_id |= (hex_to_bin(elm->rxbuf[0]) << 8) |
+ (hex_to_bin(elm->rxbuf[1]) << 4) |
+ (hex_to_bin(elm->rxbuf[2]) << 0);
+ }
+
+ /* Check for RTR frame */
+ if (elm->rxfill >= hexlen + 3 &&
+ !memcmp(&elm->rxbuf[hexlen], "RTR", 3)) {
+ frame->can_id |= CAN_RTR_FLAG;
+ }
+
+ /* Is the line long enough to hold the advertised payload?
+ * Note: RTR frames have a DLC, but no actual payload.
+ */
+ if (!(frame->can_id & CAN_RTR_FLAG) &&
+ (hexlen < frame->len * 3 + datastart)) {
+ /* Incomplete frame.
+ * Probably the ELM327's RS232 TX buffer was full.
+ * Emit an error frame and exit.
+ */
+ frame->can_id = CAN_ERR_FLAG | CAN_ERR_CRTL;
+ frame->len = CAN_ERR_DLC;
+ frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+ can327_feed_frame_to_netdev(elm, skb);
+
+ /* Signal failure to parse.
+ * The line will be re-parsed as an error line, which will fail.
+ * However, this will correctly drop the state machine back into
+ * command mode.
+ */
+ return -ENODATA;
+ }
+
+ /* Parse the data nibbles. */
+ for (i = 0; i < frame->len; i++) {
+ frame->data[i] =
+ (hex_to_bin(elm->rxbuf[datastart + 3 * i]) << 4) |
+ (hex_to_bin(elm->rxbuf[datastart + 3 * i + 1]));
+ }
+
+ /* Feed the frame to the network layer. */
+ can327_feed_frame_to_netdev(elm, skb);
+
+ return 0;
+}
+
+static void can327_parse_line(struct can327 *elm, size_t len)
+{
+ lockdep_assert_held(&elm->lock);
+
+ /* Skip empty lines */
+ if (!len)
+ return;
+
+ /* Skip echo lines */
+ if (elm->drop_next_line) {
+ elm->drop_next_line = 0;
+ return;
+ } else if (!memcmp(elm->rxbuf, "AT", 2)) {
+ return;
+ }
+
+ /* Regular parsing */
+ if (elm->state == CAN327_STATE_RECEIVING &&
+ can327_parse_frame(elm, len)) {
+ /* Parse an error line. */
+ can327_parse_error(elm, len);
+
+ /* Start afresh. */
+ can327_kick_into_cmd_mode(elm);
+ }
+}
+
+static void can327_handle_prompt(struct can327 *elm)
+{
+ struct can_frame *frame = &elm->can_frame_to_send;
+ /* Size this buffer for the largest ELM327 line we may generate,
+ * which is currently an 8 byte CAN frame's payload hexdump.
+ * Items in can327_init_script must fit here, too!
+ */
+ char local_txbuf[sizeof("0102030405060708\r")];
+
+ lockdep_assert_held(&elm->lock);
+
+ if (!elm->cmds_todo) {
+ /* Enter CAN monitor mode */
+ can327_send(elm, "ATMA\r", 5);
+ elm->state = CAN327_STATE_RECEIVING;
+
+ /* We will be in the default state once this command is
+ * sent, so enable the TX packet queue.
+ */
+ netif_wake_queue(elm->dev);
+
+ return;
+ }
+
+ /* Reconfigure ELM327 step by step as indicated by elm->cmds_todo */
+ if (test_bit(CAN327_TX_DO_INIT, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf), "%s",
+ *elm->next_init_cmd);
+
+ elm->next_init_cmd++;
+ if (!(*elm->next_init_cmd)) {
+ clear_bit(CAN327_TX_DO_INIT, &elm->cmds_todo);
+ /* Init finished. */
+ }
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_SILENT_MONITOR, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATCSM%i\r",
+ !!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_RESPONSES, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATR%i\r",
+ !(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_CAN_CONFIG, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATPC\r");
+ set_bit(CAN327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo);
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATPB%04X\r",
+ elm->can_config);
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATCP%02X\r",
+ (frame->can_id & CAN_EFF_MASK) >> 24);
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATSH%06X\r",
+ frame->can_id & CAN_EFF_MASK & ((1 << 24) - 1));
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_CANID_11BIT, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATSH%03X\r",
+ frame->can_id & CAN_SFF_MASK);
+
+ } else if (test_and_clear_bit(CAN327_TX_DO_CAN_DATA, &elm->cmds_todo)) {
+ if (frame->can_id & CAN_RTR_FLAG) {
+ /* Send an RTR frame. Their DLC is fixed.
+ * Some chips don't send them at all.
+ */
+ snprintf(local_txbuf, sizeof(local_txbuf), "ATRTR\r");
+ } else {
+ /* Send a regular CAN data frame */
+ int i;
+
+ for (i = 0; i < frame->len; i++) {
+ snprintf(&local_txbuf[2 * i],
+ sizeof(local_txbuf), "%02X",
+ frame->data[i]);
+ }
+
+ snprintf(&local_txbuf[2 * i], sizeof(local_txbuf),
+ "\r");
+ }
+
+ elm->drop_next_line = 1;
+ elm->state = CAN327_STATE_RECEIVING;
+
+ /* We will be in the default state once this command is
+ * sent, so enable the TX packet queue.
+ */
+ netif_wake_queue(elm->dev);
+ }
+
+ can327_send(elm, local_txbuf, strlen(local_txbuf));
+}
+
+static bool can327_is_ready_char(char c)
+{
+ /* Bits 0xc0 are sometimes set (randomly), hence the mask.
+ * Probably bad hardware.
+ */
+ return (c & 0x3f) == CAN327_READY_CHAR;
+}
+
+static void can327_drop_bytes(struct can327 *elm, size_t i)
+{
+ lockdep_assert_held(&elm->lock);
+
+ memmove(&elm->rxbuf[0], &elm->rxbuf[i], CAN327_SIZE_RXBUF - i);
+ elm->rxfill -= i;
+}
+
+static void can327_parse_rxbuf(struct can327 *elm, size_t first_new_char_idx)
+{
+ size_t len, pos;
+
+ lockdep_assert_held(&elm->lock);
+
+ switch (elm->state) {
+ case CAN327_STATE_NOTINIT:
+ elm->rxfill = 0;
+ break;
+
+ case CAN327_STATE_GETDUMMYCHAR:
+ /* Wait for 'y' or '>' */
+ for (pos = 0; pos < elm->rxfill; pos++) {
+ if (elm->rxbuf[pos] == CAN327_DUMMY_CHAR) {
+ can327_send(elm, "\r", 1);
+ elm->state = CAN327_STATE_GETPROMPT;
+ pos++;
+ break;
+ } else if (can327_is_ready_char(elm->rxbuf[pos])) {
+ can327_send(elm, CAN327_DUMMY_STRING, 1);
+ pos++;
+ break;
+ }
+ }
+
+ can327_drop_bytes(elm, pos);
+ break;
+
+ case CAN327_STATE_GETPROMPT:
+ /* Wait for '>' */
+ if (can327_is_ready_char(elm->rxbuf[elm->rxfill - 1]))
+ can327_handle_prompt(elm);
+
+ elm->rxfill = 0;
+ break;
+
+ case CAN327_STATE_RECEIVING:
+ /* Find <CR> delimiting feedback lines. */
+ len = first_new_char_idx;
+ while (len < elm->rxfill && elm->rxbuf[len] != '\r')
+ len++;
+
+ if (len == CAN327_SIZE_RXBUF) {
+ /* Assume the buffer ran full with garbage.
+ * Did we even connect at the right baud rate?
+ */
+ netdev_err(elm->dev,
+ "RX buffer overflow. Faulty ELM327 or UART?\n");
+ can327_uart_side_failure(elm);
+ } else if (len == elm->rxfill) {
+ if (can327_is_ready_char(elm->rxbuf[elm->rxfill - 1])) {
+ /* The ELM327's AT ST response timeout ran out,
+ * so we got a prompt.
+ * Clear RX buffer and restart listening.
+ */
+ elm->rxfill = 0;
+
+ can327_handle_prompt(elm);
+ }
+
+ /* No <CR> found - we haven't received a full line yet.
+ * Wait for more data.
+ */
+ } else {
+ /* We have a full line to parse. */
+ can327_parse_line(elm, len);
+
+ /* Remove parsed data from RX buffer. */
+ can327_drop_bytes(elm, len + 1);
+
+ /* More data to parse? */
+ if (elm->rxfill)
+ can327_parse_rxbuf(elm, 0);
+ }
+ }
+}
+
+static int can327_netdev_open(struct net_device *dev)
+{
+ struct can327 *elm = netdev_priv(dev);
+ int err;
+
+ spin_lock_bh(&elm->lock);
+
+ if (!elm->tty) {
+ spin_unlock_bh(&elm->lock);
+ return -ENODEV;
+ }
+
+ if (elm->uart_side_failure)
+ netdev_warn(elm->dev,
+ "Reopening netdev after a UART side fault has been detected.\n");
+
+ /* Clear TTY buffers */
+ elm->rxfill = 0;
+ elm->txleft = 0;
+
+ /* open_candev() checks for elm->can.bittiming.bitrate != 0 */
+ err = open_candev(dev);
+ if (err) {
+ spin_unlock_bh(&elm->lock);
+ return err;
+ }
+
+ can327_init_device(elm);
+ spin_unlock_bh(&elm->lock);
+
+ err = can_rx_offload_add_manual(dev, &elm->offload, CAN327_NAPI_WEIGHT);
+ if (err) {
+ close_candev(dev);
+ return err;
+ }
+
+ can_rx_offload_enable(&elm->offload);
+
+ elm->can.state = CAN_STATE_ERROR_ACTIVE;
+ netif_start_queue(dev);
+
+ return 0;
+}
+
+static int can327_netdev_close(struct net_device *dev)
+{
+ struct can327 *elm = netdev_priv(dev);
+
+ /* Interrupt whatever the ELM327 is doing right now */
+ spin_lock_bh(&elm->lock);
+ can327_send(elm, CAN327_DUMMY_STRING, 1);
+ spin_unlock_bh(&elm->lock);
+
+ netif_stop_queue(dev);
+
+ /* We don't flush the UART TX queue here, as we want final stop
+ * commands (like the above dummy char) to be flushed out.
+ */
+
+ can_rx_offload_disable(&elm->offload);
+ elm->can.state = CAN_STATE_STOPPED;
+ can_rx_offload_del(&elm->offload);
+ close_candev(dev);
+
+ return 0;
+}
+
+/* Send a can_frame to a TTY. */
+static netdev_tx_t can327_netdev_start_xmit(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct can327 *elm = netdev_priv(dev);
+ struct can_frame *frame = (struct can_frame *)skb->data;
+
+ if (can_dev_dropped_skb(dev, skb))
+ return NETDEV_TX_OK;
+
+ /* We shouldn't get here after a hardware fault:
+ * can_bus_off() calls netif_carrier_off()
+ */
+ if (elm->uart_side_failure) {
+ WARN_ON_ONCE(elm->uart_side_failure);
+ goto out;
+ }
+
+ netif_stop_queue(dev);
+
+ /* BHs are already disabled, so no spin_lock_bh().
+ * See Documentation/networking/netdevices.rst
+ */
+ spin_lock(&elm->lock);
+ can327_send_frame(elm, frame);
+ spin_unlock(&elm->lock);
+
+ dev->stats.tx_packets++;
+ dev->stats.tx_bytes += frame->can_id & CAN_RTR_FLAG ? 0 : frame->len;
+
+ skb_tx_timestamp(skb);
+
+out:
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops can327_netdev_ops = {
+ .ndo_open = can327_netdev_open,
+ .ndo_stop = can327_netdev_close,
+ .ndo_start_xmit = can327_netdev_start_xmit,
+ .ndo_change_mtu = can_change_mtu,
+};
+
+static const struct ethtool_ops can327_ethtool_ops = {
+ .get_ts_info = ethtool_op_get_ts_info,
+};
+
+static bool can327_is_valid_rx_char(u8 c)
+{
+ static const bool lut_char_is_valid['z'] = {
+ ['\r'] = true,
+ [' '] = true,
+ ['.'] = true,
+ ['0'] = true, true, true, true, true,
+ ['5'] = true, true, true, true, true,
+ ['<'] = true,
+ [CAN327_READY_CHAR] = true,
+ ['?'] = true,
+ ['A'] = true, true, true, true, true, true, true,
+ ['H'] = true, true, true, true, true, true, true,
+ ['O'] = true, true, true, true, true, true, true,
+ ['V'] = true, true, true, true, true,
+ ['a'] = true,
+ ['b'] = true,
+ ['v'] = true,
+ [CAN327_DUMMY_CHAR] = true,
+ };
+ BUILD_BUG_ON(CAN327_DUMMY_CHAR >= 'z');
+
+ return (c < ARRAY_SIZE(lut_char_is_valid) && lut_char_is_valid[c]);
+}
+
+/* Handle incoming ELM327 ASCII data.
+ * This will not be re-entered while running, but other ldisc
+ * functions may be called in parallel.
+ */
+static void can327_ldisc_rx(struct tty_struct *tty, const u8 *cp,
+ const u8 *fp, size_t count)
+{
+ struct can327 *elm = tty->disc_data;
+ size_t first_new_char_idx;
+
+ if (elm->uart_side_failure)
+ return;
+
+ spin_lock_bh(&elm->lock);
+
+ /* Store old rxfill, so can327_parse_rxbuf() will have
+ * the option of skipping already checked characters.
+ */
+ first_new_char_idx = elm->rxfill;
+
+ while (count--) {
+ if (elm->rxfill >= CAN327_SIZE_RXBUF) {
+ netdev_err(elm->dev,
+ "Receive buffer overflowed. Bad chip or wiring? count = %zu",
+ count);
+ goto uart_failure;
+ }
+ if (fp && *fp++) {
+ netdev_err(elm->dev,
+ "Error in received character stream. Check your wiring.");
+ goto uart_failure;
+ }
+
+ /* Ignore NUL characters, which the PIC microcontroller may
+ * inadvertently insert due to a known hardware bug.
+ * See ELM327 documentation, which refers to a Microchip PIC
+ * bug description.
+ */
+ if (*cp) {
+ /* Check for stray characters on the UART line.
+ * Likely caused by bad hardware.
+ */
+ if (!can327_is_valid_rx_char(*cp)) {
+ netdev_err(elm->dev,
+ "Received illegal character %02x.\n",
+ *cp);
+ goto uart_failure;
+ }
+
+ elm->rxbuf[elm->rxfill++] = *cp;
+ }
+
+ cp++;
+ }
+
+ can327_parse_rxbuf(elm, first_new_char_idx);
+ spin_unlock_bh(&elm->lock);
+
+ return;
+uart_failure:
+ can327_uart_side_failure(elm);
+ spin_unlock_bh(&elm->lock);
+}
+
+/* Write out remaining transmit buffer.
+ * Scheduled when TTY is writable.
+ */
+static void can327_ldisc_tx_worker(struct work_struct *work)
+{
+ struct can327 *elm = container_of(work, struct can327, tx_work);
+ ssize_t written;
+
+ if (elm->uart_side_failure)
+ return;
+
+ spin_lock_bh(&elm->lock);
+
+ if (elm->txleft) {
+ written = elm->tty->ops->write(elm->tty, elm->txhead,
+ elm->txleft);
+ if (written < 0) {
+ netdev_err(elm->dev, "Failed to write to tty %s.\n",
+ elm->tty->name);
+ can327_uart_side_failure(elm);
+
+ spin_unlock_bh(&elm->lock);
+ return;
+ }
+
+ elm->txleft -= written;
+ elm->txhead += written;
+ }
+
+ if (!elm->txleft)
+ clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+
+ spin_unlock_bh(&elm->lock);
+}
+
+/* Called by the driver when there's room for more data. */
+static void can327_ldisc_tx_wakeup(struct tty_struct *tty)
+{
+ struct can327 *elm = tty->disc_data;
+
+ schedule_work(&elm->tx_work);
+}
+
+/* ELM327 can only handle bitrates that are integer divisors of 500 kHz,
+ * or 7/8 of that. Divisors are 1 to 64.
+ * Currently we don't implement support for 7/8 rates.
+ */
+static const u32 can327_bitrate_const[] = {
+ 7812, 7936, 8064, 8196, 8333, 8474, 8620, 8771,
+ 8928, 9090, 9259, 9433, 9615, 9803, 10000, 10204,
+ 10416, 10638, 10869, 11111, 11363, 11627, 11904, 12195,
+ 12500, 12820, 13157, 13513, 13888, 14285, 14705, 15151,
+ 15625, 16129, 16666, 17241, 17857, 18518, 19230, 20000,
+ 20833, 21739, 22727, 23809, 25000, 26315, 27777, 29411,
+ 31250, 33333, 35714, 38461, 41666, 45454, 50000, 55555,
+ 62500, 71428, 83333, 100000, 125000, 166666, 250000, 500000
+};
+
+static int can327_ldisc_open(struct tty_struct *tty)
+{
+ struct net_device *dev;
+ struct can327 *elm;
+ int err;
+
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
+ if (!tty->ops->write)
+ return -EOPNOTSUPP;
+
+ dev = alloc_candev(sizeof(struct can327), 0);
+ if (!dev)
+ return -ENFILE;
+ elm = netdev_priv(dev);
+
+ /* Configure TTY interface */
+ tty->receive_room = 65536; /* We don't flow control */
+ spin_lock_init(&elm->lock);
+ INIT_WORK(&elm->tx_work, can327_ldisc_tx_worker);
+
+ /* Configure CAN metadata */
+ elm->can.bitrate_const = can327_bitrate_const;
+ elm->can.bitrate_const_cnt = ARRAY_SIZE(can327_bitrate_const);
+ elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
+
+ /* Configure netdev interface */
+ elm->dev = dev;
+ dev->netdev_ops = &can327_netdev_ops;
+ dev->ethtool_ops = &can327_ethtool_ops;
+
+ /* Mark ldisc channel as alive */
+ elm->tty = tty;
+ tty->disc_data = elm;
+
+ /* Let 'er rip */
+ err = register_candev(elm->dev);
+ if (err) {
+ free_candev(elm->dev);
+ return err;
+ }
+
+ netdev_info(elm->dev, "can327 on %s.\n", tty->name);
+
+ return 0;
+}
+
+/* Close down a can327 channel.
+ * This means flushing out any pending queues, and then returning.
+ * This call is serialized against other ldisc functions:
+ * Once this is called, no other ldisc function of ours is entered.
+ *
+ * We also use this function for a hangup event.
+ */
+static void can327_ldisc_close(struct tty_struct *tty)
+{
+ struct can327 *elm = tty->disc_data;
+
+ /* unregister_netdev() calls .ndo_stop() so we don't have to. */
+ unregister_candev(elm->dev);
+
+ /* Give UART one final chance to flush.
+ * No need to clear TTY_DO_WRITE_WAKEUP since .write_wakeup() is
+ * serialised against .close() and will not be called once we return.
+ */
+ flush_work(&elm->tx_work);
+
+ /* Mark channel as dead */
+ spin_lock_bh(&elm->lock);
+ tty->disc_data = NULL;
+ elm->tty = NULL;
+ spin_unlock_bh(&elm->lock);
+
+ netdev_info(elm->dev, "can327 off %s.\n", tty->name);
+
+ free_candev(elm->dev);
+}
+
+static int can327_ldisc_ioctl(struct tty_struct *tty, unsigned int cmd,
+ unsigned long arg)
+{
+ struct can327 *elm = tty->disc_data;
+ unsigned int tmp;
+
+ switch (cmd) {
+ case SIOCGIFNAME:
+ tmp = strnlen(elm->dev->name, IFNAMSIZ - 1) + 1;
+ if (copy_to_user((void __user *)arg, elm->dev->name, tmp))
+ return -EFAULT;
+ return 0;
+
+ case SIOCSIFHWADDR:
+ return -EINVAL;
+
+ default:
+ return tty_mode_ioctl(tty, cmd, arg);
+ }
+}
+
+static struct tty_ldisc_ops can327_ldisc = {
+ .owner = THIS_MODULE,
+ .name = KBUILD_MODNAME,
+ .num = N_CAN327,
+ .receive_buf = can327_ldisc_rx,
+ .write_wakeup = can327_ldisc_tx_wakeup,
+ .open = can327_ldisc_open,
+ .close = can327_ldisc_close,
+ .ioctl = can327_ldisc_ioctl,
+};
+
+static int __init can327_init(void)
+{
+ int status;
+
+ status = tty_register_ldisc(&can327_ldisc);
+ if (status)
+ pr_err("Can't register line discipline\n");
+
+ return status;
+}
+
+static void __exit can327_exit(void)
+{
+ /* This will only be called when all channels have been closed by
+ * userspace - tty_ldisc.c takes care of the module's refcount.
+ */
+ tty_unregister_ldisc(&can327_ldisc);
+}
+
+module_init(can327_init);
+module_exit(can327_exit);
+
+MODULE_ALIAS_LDISC(N_CAN327);
+MODULE_DESCRIPTION("ELM327 based CAN interface");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Max Staudt <max@enpas.org>");