This is to clarify that this driver is not a product of ELM Electronics.
*~
*.o
-elmcan-usermode
-
*.cmd
*.ko
*.mod.c
-obj-m += elmcan.o
+obj-m += can327.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
--- /dev/null
+// 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) "can327: " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/if_ether.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/version.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/led.h>
+#include <linux/can/rx-offload.h>
+
+/* Line discipline ID number.
+ * Starting with Linux v5.18-rc1, N_DEVELOPMENT is defined as 29:
+ * https://github.com/torvalds/linux/commit/c2faf737abfb10f88f2d2612d573e9edc3c42c37
+ */
+#ifndef N_DEVELOPMENT
+#define N_DEVELOPMENT 29
+#endif
+
+/* Compatibility for Linux < 5.11 */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,11,0)
+#define len can_dlc
+#endif
+
+#define ELM327_NAPI_WEIGHT 4
+
+#define ELM327_SIZE_RXBUF 224
+#define ELM327_SIZE_TXBUF 32
+
+#define ELM327_CAN_CONFIG_SEND_SFF 0x8000
+#define ELM327_CAN_CONFIG_VARIABLE_DLC 0x4000
+#define ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF 0x2000
+#define ELM327_CAN_CONFIG_BAUDRATE_MULT_8_7 0x1000
+
+#define ELM327_DUMMY_CHAR 'y'
+#define ELM327_DUMMY_STRING "y"
+#define ELM327_READY_CHAR '>'
+
+/* Bits in elm->cmds_todo */
+enum elm327_to_to_do_bits {
+ ELM327_TX_DO_CAN_DATA = 0,
+ ELM327_TX_DO_CANID_11BIT,
+ ELM327_TX_DO_CANID_29BIT_LOW,
+ ELM327_TX_DO_CANID_29BIT_HIGH,
+ ELM327_TX_DO_CAN_CONFIG_PART2,
+ ELM327_TX_DO_CAN_CONFIG,
+ ELM327_TX_DO_RESPONSES,
+ ELM327_TX_DO_SILENT_MONITOR,
+ ELM327_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 rxbuf[ELM327_SIZE_RXBUF];
+ u8 txbuf[ELM327_SIZE_TXBUF] ____cacheline_aligned;
+
+ /* 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 {
+ ELM327_STATE_NOTINIT = 0,
+ ELM327_STATE_GETDUMMYCHAR,
+ ELM327_STATE_GETPROMPT,
+ ELM327_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 elm327_uart_side_failure(struct can327 *elm);
+
+static void elm327_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);
+ elm327_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 ELM327_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 elm327_kick_into_cmd_mode(struct can327 *elm)
+{
+ lockdep_assert_held(&elm->lock);
+
+ if (elm->state != ELM327_STATE_GETDUMMYCHAR &&
+ elm->state != ELM327_STATE_GETPROMPT) {
+ elm327_send(elm, ELM327_DUMMY_STRING, 1);
+
+ elm->state = ELM327_STATE_GETDUMMYCHAR;
+ }
+}
+
+/* Schedule a CAN frame and necessary config changes to be sent to the TTY. */
+static void elm327_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 & CAN_EFF_FLAG) ^
+ (elm->can_frame_to_send.can_id & CAN_EFF_FLAG)) {
+ elm->can_config = (frame->can_id & CAN_EFF_FLAG
+ ? 0
+ : ELM327_CAN_CONFIG_SEND_SFF)
+ | ELM327_CAN_CONFIG_VARIABLE_DLC
+ | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
+ | elm->can_bitrate_divisor;
+
+ set_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
+ }
+
+ if (frame->can_id & CAN_EFF_FLAG) {
+ clear_bit(ELM327_TX_DO_CANID_11BIT, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ } else {
+ set_bit(ELM327_TX_DO_CANID_11BIT, &elm->cmds_todo);
+ clear_bit(ELM327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo);
+ clear_bit(ELM327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ }
+ }
+
+ /* Schedule the CAN frame itself. */
+ elm->can_frame_to_send = *frame;
+ set_bit(ELM327_TX_DO_CAN_DATA, &elm->cmds_todo);
+
+ elm327_kick_into_cmd_mode(elm);
+}
+
+/* ELM327 initialisation sequence.
+ * The line length is limited by the buffer in elm327_handle_prompt().
+ */
+static char *elm327_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 elm327_init(struct can327 *elm)
+{
+ lockdep_assert_held(&elm->lock);
+
+ elm->state = ELM327_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 bit timing constants in can327_bittiming_const will
+ * limit the user to the right values.
+ */
+ elm->can_bitrate_divisor = 500000 / elm->can.bittiming.bitrate;
+ elm->can_config = ELM327_CAN_CONFIG_SEND_SFF
+ | ELM327_CAN_CONFIG_VARIABLE_DLC
+ | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
+ | elm->can_bitrate_divisor;
+
+ /* Configure ELM327 and then start monitoring */
+ elm->next_init_cmd = &elm327_init_script[0];
+ set_bit(ELM327_TX_DO_INIT, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_SILENT_MONITOR, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_RESPONSES, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
+
+ elm327_kick_into_cmd_mode(elm);
+}
+
+static void elm327_feed_frame_to_netdev(struct can327 *elm,
+ struct sk_buff *skb)
+{
+ lockdep_assert_held(&elm->lock);
+
+ if (!netif_running(elm->dev))
+ 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++;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+ /* Wake NAPI */
+ can_rx_offload_irq_finish(&elm->offload);
+#endif
+}
+
+/* Called when we're out of ideas and just want it all to end. */
+static inline void elm327_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;
+ elm327_feed_frame_to_netdev(elm, skb);
+}
+
+/* Compare buffer to string length, then compare buffer to fixed string.
+ * This ensures two things:
+ * - It flags cases where the fixed string is only the start of the
+ * buffer, rather than exactly all of it.
+ * - It avoids byte comparisons in case the length doesn't match.
+ *
+ * strncmp() cannot be used here because it accepts the following wrong case:
+ * strncmp("CAN ER", "CAN ERROR", 6);
+ * This must fail, hence this helper function.
+ */
+static inline int check_len_then_cmp(const u8 *mem, size_t mem_len, const char *str)
+{
+ size_t str_len = strlen(str);
+
+ return (mem_len == str_len) && !memcmp(mem, str, str_len);
+}
+
+static void elm327_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 (check_len_then_cmp(elm->rxbuf, len, "UNABLE TO CONNECT")) {
+ netdev_err(elm->dev,
+ "ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
+ } else if (check_len_then_cmp(elm->rxbuf, len, "BUFFER FULL")) {
+ /* This will only happen if the last data line was complete.
+ * Otherwise, elm327_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 (check_len_then_cmp(elm->rxbuf, len, "BUS ERROR")) {
+ frame->can_id |= CAN_ERR_BUSERROR;
+ } else if (check_len_then_cmp(elm->rxbuf, len, "CAN ERROR")) {
+ frame->can_id |= CAN_ERR_PROT;
+ } else if (check_len_then_cmp(elm->rxbuf, len, "<RX ERROR")) {
+ frame->can_id |= CAN_ERR_PROT;
+ } else if (check_len_then_cmp(elm->rxbuf, len, "BUS BUSY")) {
+ frame->can_id |= CAN_ERR_PROT;
+ frame->data[2] = CAN_ERR_PROT_OVERLOAD;
+ } else if (check_len_then_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.
+ */
+ }
+
+ elm327_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 elm327_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.
+ */
+ 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.
+ */
+ 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.
+ */
+ 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;
+ elm327_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. */
+ elm327_feed_frame_to_netdev(elm, skb);
+
+ return 0;
+}
+
+static void elm327_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 == ELM327_STATE_RECEIVING &&
+ elm327_parse_frame(elm, len)) {
+ /* Parse an error line. */
+ elm327_parse_error(elm, len);
+
+ /* Start afresh. */
+ elm327_kick_into_cmd_mode(elm);
+ }
+}
+
+static void elm327_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 elm327_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 */
+ elm327_send(elm, "ATMA\r", 5);
+ elm->state = ELM327_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(ELM327_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(ELM327_TX_DO_INIT, &elm->cmds_todo);
+ /* Init finished. */
+ }
+
+ } else if (test_and_clear_bit(ELM327_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(ELM327_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(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo)) {
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATPC\r");
+ set_bit(ELM327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo);
+
+ } else if (test_and_clear_bit(ELM327_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(ELM327_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(ELM327_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(ELM327_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(ELM327_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 = ELM327_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);
+ }
+
+ elm327_send(elm, local_txbuf, strlen(local_txbuf));
+}
+
+static bool elm327_is_ready_char(char c)
+{
+ /* Bits 0xc0 are sometimes set (randomly), hence the mask.
+ * Probably bad hardware.
+ */
+ return (c & 0x3f) == ELM327_READY_CHAR;
+}
+
+static void elm327_drop_bytes(struct can327 *elm, size_t i)
+{
+ lockdep_assert_held(&elm->lock);
+
+ memmove(&elm->rxbuf[0], &elm->rxbuf[i], ELM327_SIZE_RXBUF - i);
+ elm->rxfill -= i;
+}
+
+static void elm327_parse_rxbuf(struct can327 *elm)
+{
+ size_t len;
+ int i;
+
+ lockdep_assert_held(&elm->lock);
+
+ switch (elm->state) {
+ case ELM327_STATE_NOTINIT:
+ elm->rxfill = 0;
+ break;
+
+ case ELM327_STATE_GETDUMMYCHAR:
+ {
+ /* Wait for 'y' or '>' */
+ for (i = 0; i < elm->rxfill; i++) {
+ if (elm->rxbuf[i] == ELM327_DUMMY_CHAR) {
+ elm327_send(elm, "\r", 1);
+ elm->state = ELM327_STATE_GETPROMPT;
+ i++;
+ break;
+ } else if (elm327_is_ready_char(elm->rxbuf[i])) {
+ elm327_send(elm, ELM327_DUMMY_STRING, 1);
+ i++;
+ break;
+ }
+ }
+
+ elm327_drop_bytes(elm, i);
+
+ break;
+ }
+
+ case ELM327_STATE_GETPROMPT:
+ /* Wait for '>' */
+ if (elm327_is_ready_char(elm->rxbuf[elm->rxfill - 1]))
+ elm327_handle_prompt(elm);
+
+ elm->rxfill = 0;
+ break;
+
+ case ELM327_STATE_RECEIVING:
+ /* Find <CR> delimiting feedback lines. */
+ for (len = 0;
+ (len < elm->rxfill) && (elm->rxbuf[len] != '\r');
+ len++) {
+ /* empty loop */
+ }
+
+ if (len == ELM327_SIZE_RXBUF) {
+ /* Line exceeds buffer. It's probably all garbage.
+ * Did we even connect at the right baud rate?
+ */
+ netdev_err(elm->dev,
+ "RX buffer overflow. Faulty ELM327 or UART?\n");
+ elm327_uart_side_failure(elm);
+ break;
+ } else if (len == elm->rxfill) {
+ if (elm327_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;
+
+ elm327_handle_prompt(elm);
+ break;
+ }
+
+ /* No <CR> found - we haven't received a full line yet.
+ * Wait for more data.
+ */
+ break;
+ }
+
+ /* We have a full line to parse. */
+ elm327_parse_line(elm, len);
+
+ /* Remove parsed data from RX buffer. */
+ elm327_drop_bytes(elm, len + 1);
+
+ /* More data to parse? */
+ if (elm->rxfill)
+ elm327_parse_rxbuf(elm);
+ }
+}
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,10,0)
+/* Dummy needed to use can_rx_offload */
+static struct sk_buff *can327_mailbox_read(struct can_rx_offload *offload,
+ unsigned int n, u32 *timestamp,
+ bool drop)
+{
+ WARN_ON_ONCE(1); /* This function is a dummy, so don't call it! */
+
+ return ERR_PTR(-ENOBUFS);
+}
+#endif
+
+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;
+ }
+
+ elm327_init(elm);
+ spin_unlock_bh(&elm->lock);
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,10,0)
+ elm->offload.mailbox_read = can327_mailbox_read;
+ err = can_rx_offload_add_fifo(dev, &elm->offload, ELM327_NAPI_WEIGHT);
+#else
+ err = can_rx_offload_add_manual(dev, &elm->offload, ELM327_NAPI_WEIGHT);
+#endif
+ if (err) {
+ close_candev(dev);
+ return err;
+ }
+
+ can_rx_offload_enable(&elm->offload);
+
+ can_led_event(dev, CAN_LED_EVENT_OPEN);
+ 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);
+ elm327_send(elm, ELM327_DUMMY_STRING, 1);
+ spin_unlock_bh(&elm->lock);
+
+ netif_stop_queue(dev);
+
+ /* Give UART one final chance to flush. */
+ clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+ flush_work(&elm->tx_work);
+
+ can_rx_offload_disable(&elm->offload);
+ elm->can.state = CAN_STATE_STOPPED;
+ can_rx_offload_del(&elm->offload);
+ close_candev(dev);
+ can_led_event(dev, CAN_LED_EVENT_STOP);
+
+ 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_dropped_invalid_skb(dev, skb))
+ return NETDEV_TX_OK;
+
+ /* BHs are already disabled, so no spin_lock_bh().
+ * See Documentation/networking/netdevices.txt
+ */
+ spin_lock(&elm->lock);
+
+ /* We shouldn't get here after a hardware fault:
+ * can_bus_off() calls netif_carrier_off()
+ */
+ WARN_ON_ONCE(elm->uart_side_failure);
+
+ if (!elm->tty ||
+ elm->uart_side_failure ||
+ elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
+ spin_unlock(&elm->lock);
+ goto out;
+ }
+
+ netif_stop_queue(dev);
+
+ elm327_send_frame(elm, frame);
+ spin_unlock(&elm->lock);
+
+ dev->stats.tx_packets++;
+ dev->stats.tx_bytes += frame->len;
+
+ can_led_event(dev, CAN_LED_EVENT_TX);
+
+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 bool can327_is_valid_rx_char(char c)
+{
+ return (isdigit(c) ||
+ isupper(c) ||
+ c == ELM327_DUMMY_CHAR ||
+ c == ELM327_READY_CHAR ||
+ c == '<' ||
+ c == 'a' ||
+ c == 'b' ||
+ c == 'v' ||
+ c == '.' ||
+ c == '?' ||
+ c == '\r' ||
+ c == ' ');
+}
+
+/* Handle incoming ELM327 ASCII data.
+ * This will not be re-entered while running, but other ldisc
+ * functions may be called in parallel.
+ */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
+static void can327_ldisc_rx(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
+#else
+static void can327_ldisc_rx(struct tty_struct *tty,
+ const unsigned char *cp, const char *fp, int count)
+#endif
+{
+ struct can327 *elm = (struct can327 *)tty->disc_data;
+
+ spin_lock_bh(&elm->lock);
+
+ if (elm->uart_side_failure)
+ goto out;
+
+ while (count-- && elm->rxfill < ELM327_SIZE_RXBUF) {
+ if (fp && *fp++) {
+ netdev_err(elm->dev, "Error in received character stream. Check your wiring.");
+
+ elm327_uart_side_failure(elm);
+
+ goto out;
+ }
+
+ /* 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 != 0) {
+ /* 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);
+ elm327_uart_side_failure(elm);
+
+ goto out;
+ }
+
+ elm->rxbuf[elm->rxfill++] = *cp;
+ }
+
+ cp++;
+ }
+
+ if (count >= 0) {
+ netdev_err(elm->dev, "Receive buffer overflowed. Bad chip or wiring?");
+
+ elm327_uart_side_failure(elm);
+
+ goto out;
+ }
+
+ elm327_parse_rxbuf(elm);
+
+out:
+ 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);
+ elm327_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);
+ } else {
+ 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 = (struct can327 *)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[64] = {
+ 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
+};
+
+/* Dummy needed to use bitrate_const */
+static int can327_do_set_bittiming(struct net_device *netdev)
+{
+ return 0;
+}
+
+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.do_set_bittiming = can327_do_set_bittiming;
+ elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
+
+ /* Configure netdev interface */
+ elm->dev = dev;
+ dev->netdev_ops = &can327_netdev_ops;
+
+ /* Mark ldisc channel as alive */
+ elm->tty = tty;
+ tty->disc_data = elm;
+
+ devm_can_led_init(elm->dev);
+
+ /* Let 'er rip */
+ err = register_candev(elm->dev);
+ if (err)
+ goto out_err;
+
+ netdev_info(elm->dev, "can327 on %s.\n", tty->name);
+
+ return 0;
+
+out_err:
+ free_candev(elm->dev);
+ return err;
+}
+
+/* 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 = (struct can327 *)tty->disc_data;
+
+ /* unregister_netdev() calls .ndo_stop() so we don't have to.
+ * Our .ndo_stop() also flushes the TTY write wakeup handler,
+ * so we can safely set elm->tty = NULL after this.
+ */
+ unregister_candev(elm->dev);
+
+ /* 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,
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,17,0)
+ struct file *file,
+#endif
+ unsigned int cmd, unsigned long arg)
+{
+ struct can327 *elm = (struct can327 *)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:
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,16,0)
+ return tty_mode_ioctl(tty, file, cmd, arg);
+#else
+ return tty_mode_ioctl(tty, cmd, arg);
+#endif
+ }
+}
+
+static struct tty_ldisc_ops can327_ldisc = {
+ .owner = THIS_MODULE,
+ .name = "can327",
+ .num = N_DEVELOPMENT,
+ .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;
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
+ status = tty_register_ldisc(N_DEVELOPMENT, &can327_ldisc);
+#else
+ status = tty_register_ldisc(&can327_ldisc);
+#endif
+ 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.
+ */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
+ int status;
+
+ status = tty_unregister_ldisc(N_DEVELOPMENT);
+ if (status)
+ pr_err("Can't unregister line discipline (error: %d)\n",
+ status);
+#else
+ tty_unregister_ldisc(&can327_ldisc);
+#endif
+}
+
+module_init(can327_init);
+module_exit(can327_exit);
+
+MODULE_ALIAS_LDISC(N_DEVELOPMENT);
+MODULE_DESCRIPTION("ELM327 based CAN interface");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Max Staudt <max-linux@enpas.org>");
-PACKAGE_NAME="elmcan"
+PACKAGE_NAME="can327"
PACKAGE_VERSION="1"
BUILT_MODULE_NAME[0]="$PACKAGE_NAME"
DEST_MODULE_LOCATION[0]="/updates/dkms"
+++ /dev/null
-// 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.
- *
- * elmcan.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) "elmcan: " fmt
-
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/moduleparam.h>
-
-#include <linux/atomic.h>
-#include <linux/bitops.h>
-#include <linux/ctype.h>
-#include <linux/delay.h>
-#include <linux/errno.h>
-#include <linux/if_ether.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/version.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/led.h>
-#include <linux/can/rx-offload.h>
-
-/* Line discipline ID number.
- * Starting with Linux v5.18-rc1, N_DEVELOPMENT is defined as 29:
- * https://github.com/torvalds/linux/commit/c2faf737abfb10f88f2d2612d573e9edc3c42c37
- */
-#ifndef N_DEVELOPMENT
-#define N_DEVELOPMENT 29
-#endif
-
-/* Compatibility for Linux < 5.11 */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,11,0)
-#define len can_dlc
-#endif
-
-#define ELM327_NAPI_WEIGHT 4
-
-#define ELM327_SIZE_RXBUF 224
-#define ELM327_SIZE_TXBUF 32
-
-#define ELM327_CAN_CONFIG_SEND_SFF 0x8000
-#define ELM327_CAN_CONFIG_VARIABLE_DLC 0x4000
-#define ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF 0x2000
-#define ELM327_CAN_CONFIG_BAUDRATE_MULT_8_7 0x1000
-
-#define ELM327_DUMMY_CHAR 'y'
-#define ELM327_DUMMY_STRING "y"
-#define ELM327_READY_CHAR '>'
-
-/* Bits in elm->cmds_todo */
-enum elm327_to_to_do_bits {
- ELM327_TX_DO_CAN_DATA = 0,
- ELM327_TX_DO_CANID_11BIT,
- ELM327_TX_DO_CANID_29BIT_LOW,
- ELM327_TX_DO_CANID_29BIT_HIGH,
- ELM327_TX_DO_CAN_CONFIG_PART2,
- ELM327_TX_DO_CAN_CONFIG,
- ELM327_TX_DO_RESPONSES,
- ELM327_TX_DO_SILENT_MONITOR,
- ELM327_TX_DO_INIT
-};
-
-struct elmcan {
- /* This must be the first member when using alloc_candev() */
- struct can_priv can;
-
- struct can_rx_offload offload;
-
- /* TTY buffers */
- u8 rxbuf[ELM327_SIZE_RXBUF];
- u8 txbuf[ELM327_SIZE_TXBUF] ____cacheline_aligned;
-
- /* 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 {
- ELM327_STATE_NOTINIT = 0,
- ELM327_STATE_GETDUMMYCHAR,
- ELM327_STATE_GETPROMPT,
- ELM327_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 elm327_uart_side_failure(struct elmcan *elm);
-
-static void elm327_send(struct elmcan *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);
- elm327_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 ELM327_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 elm327_kick_into_cmd_mode(struct elmcan *elm)
-{
- lockdep_assert_held(&elm->lock);
-
- if (elm->state != ELM327_STATE_GETDUMMYCHAR &&
- elm->state != ELM327_STATE_GETPROMPT) {
- elm327_send(elm, ELM327_DUMMY_STRING, 1);
-
- elm->state = ELM327_STATE_GETDUMMYCHAR;
- }
-}
-
-/* Schedule a CAN frame and necessary config changes to be sent to the TTY. */
-static void elm327_send_frame(struct elmcan *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 & CAN_EFF_FLAG) ^
- (elm->can_frame_to_send.can_id & CAN_EFF_FLAG)) {
- elm->can_config = (frame->can_id & CAN_EFF_FLAG
- ? 0
- : ELM327_CAN_CONFIG_SEND_SFF)
- | ELM327_CAN_CONFIG_VARIABLE_DLC
- | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
- | elm->can_bitrate_divisor;
-
- set_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
- }
-
- if (frame->can_id & CAN_EFF_FLAG) {
- clear_bit(ELM327_TX_DO_CANID_11BIT, &elm->cmds_todo);
- set_bit(ELM327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo);
- set_bit(ELM327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo);
- } else {
- set_bit(ELM327_TX_DO_CANID_11BIT, &elm->cmds_todo);
- clear_bit(ELM327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo);
- clear_bit(ELM327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo);
- }
- }
-
- /* Schedule the CAN frame itself. */
- elm->can_frame_to_send = *frame;
- set_bit(ELM327_TX_DO_CAN_DATA, &elm->cmds_todo);
-
- elm327_kick_into_cmd_mode(elm);
-}
-
-/* ELM327 initialisation sequence.
- * The line length is limited by the buffer in elm327_handle_prompt().
- */
-static char *elm327_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 elm327_init(struct elmcan *elm)
-{
- lockdep_assert_held(&elm->lock);
-
- elm->state = ELM327_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 bit timing constants in elmcan_bittiming_const will
- * limit the user to the right values.
- */
- elm->can_bitrate_divisor = 500000 / elm->can.bittiming.bitrate;
- elm->can_config = ELM327_CAN_CONFIG_SEND_SFF
- | ELM327_CAN_CONFIG_VARIABLE_DLC
- | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
- | elm->can_bitrate_divisor;
-
- /* Configure ELM327 and then start monitoring */
- elm->next_init_cmd = &elm327_init_script[0];
- set_bit(ELM327_TX_DO_INIT, &elm->cmds_todo);
- set_bit(ELM327_TX_DO_SILENT_MONITOR, &elm->cmds_todo);
- set_bit(ELM327_TX_DO_RESPONSES, &elm->cmds_todo);
- set_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
-
- elm327_kick_into_cmd_mode(elm);
-}
-
-static void elm327_feed_frame_to_netdev(struct elmcan *elm,
- struct sk_buff *skb)
-{
- lockdep_assert_held(&elm->lock);
-
- if (!netif_running(elm->dev))
- 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++;
-
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
- /* Wake NAPI */
- can_rx_offload_irq_finish(&elm->offload);
-#endif
-}
-
-/* Called when we're out of ideas and just want it all to end. */
-static inline void elm327_uart_side_failure(struct elmcan *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;
- elm327_feed_frame_to_netdev(elm, skb);
-}
-
-/* Compare buffer to string length, then compare buffer to fixed string.
- * This ensures two things:
- * - It flags cases where the fixed string is only the start of the
- * buffer, rather than exactly all of it.
- * - It avoids byte comparisons in case the length doesn't match.
- *
- * strncmp() cannot be used here because it accepts the following wrong case:
- * strncmp("CAN ER", "CAN ERROR", 6);
- * This must fail, hence this helper function.
- */
-static inline int check_len_then_cmp(const u8 *mem, size_t mem_len, const char *str)
-{
- size_t str_len = strlen(str);
-
- return (mem_len == str_len) && !memcmp(mem, str, str_len);
-}
-
-static void elm327_parse_error(struct elmcan *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 (check_len_then_cmp(elm->rxbuf, len, "UNABLE TO CONNECT")) {
- netdev_err(elm->dev,
- "ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
- } else if (check_len_then_cmp(elm->rxbuf, len, "BUFFER FULL")) {
- /* This will only happen if the last data line was complete.
- * Otherwise, elm327_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 (check_len_then_cmp(elm->rxbuf, len, "BUS ERROR")) {
- frame->can_id |= CAN_ERR_BUSERROR;
- } else if (check_len_then_cmp(elm->rxbuf, len, "CAN ERROR")) {
- frame->can_id |= CAN_ERR_PROT;
- } else if (check_len_then_cmp(elm->rxbuf, len, "<RX ERROR")) {
- frame->can_id |= CAN_ERR_PROT;
- } else if (check_len_then_cmp(elm->rxbuf, len, "BUS BUSY")) {
- frame->can_id |= CAN_ERR_PROT;
- frame->data[2] = CAN_ERR_PROT_OVERLOAD;
- } else if (check_len_then_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.
- */
- }
-
- elm327_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 elm327_parse_frame(struct elmcan *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.
- */
- 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.
- */
- 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.
- */
- 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;
- elm327_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. */
- elm327_feed_frame_to_netdev(elm, skb);
-
- return 0;
-}
-
-static void elm327_parse_line(struct elmcan *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 == ELM327_STATE_RECEIVING &&
- elm327_parse_frame(elm, len)) {
- /* Parse an error line. */
- elm327_parse_error(elm, len);
-
- /* Start afresh. */
- elm327_kick_into_cmd_mode(elm);
- }
-}
-
-static void elm327_handle_prompt(struct elmcan *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 elm327_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 */
- elm327_send(elm, "ATMA\r", 5);
- elm->state = ELM327_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(ELM327_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(ELM327_TX_DO_INIT, &elm->cmds_todo);
- /* Init finished. */
- }
-
- } else if (test_and_clear_bit(ELM327_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(ELM327_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(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo)) {
- snprintf(local_txbuf, sizeof(local_txbuf),
- "ATPC\r");
- set_bit(ELM327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo);
-
- } else if (test_and_clear_bit(ELM327_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(ELM327_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(ELM327_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(ELM327_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(ELM327_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 = ELM327_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);
- }
-
- elm327_send(elm, local_txbuf, strlen(local_txbuf));
-}
-
-static bool elm327_is_ready_char(char c)
-{
- /* Bits 0xc0 are sometimes set (randomly), hence the mask.
- * Probably bad hardware.
- */
- return (c & 0x3f) == ELM327_READY_CHAR;
-}
-
-static void elm327_drop_bytes(struct elmcan *elm, size_t i)
-{
- lockdep_assert_held(&elm->lock);
-
- memmove(&elm->rxbuf[0], &elm->rxbuf[i], ELM327_SIZE_RXBUF - i);
- elm->rxfill -= i;
-}
-
-static void elm327_parse_rxbuf(struct elmcan *elm)
-{
- size_t len;
- int i;
-
- lockdep_assert_held(&elm->lock);
-
- switch (elm->state) {
- case ELM327_STATE_NOTINIT:
- elm->rxfill = 0;
- break;
-
- case ELM327_STATE_GETDUMMYCHAR:
- {
- /* Wait for 'y' or '>' */
- for (i = 0; i < elm->rxfill; i++) {
- if (elm->rxbuf[i] == ELM327_DUMMY_CHAR) {
- elm327_send(elm, "\r", 1);
- elm->state = ELM327_STATE_GETPROMPT;
- i++;
- break;
- } else if (elm327_is_ready_char(elm->rxbuf[i])) {
- elm327_send(elm, ELM327_DUMMY_STRING, 1);
- i++;
- break;
- }
- }
-
- elm327_drop_bytes(elm, i);
-
- break;
- }
-
- case ELM327_STATE_GETPROMPT:
- /* Wait for '>' */
- if (elm327_is_ready_char(elm->rxbuf[elm->rxfill - 1]))
- elm327_handle_prompt(elm);
-
- elm->rxfill = 0;
- break;
-
- case ELM327_STATE_RECEIVING:
- /* Find <CR> delimiting feedback lines. */
- for (len = 0;
- (len < elm->rxfill) && (elm->rxbuf[len] != '\r');
- len++) {
- /* empty loop */
- }
-
- if (len == ELM327_SIZE_RXBUF) {
- /* Line exceeds buffer. It's probably all garbage.
- * Did we even connect at the right baud rate?
- */
- netdev_err(elm->dev,
- "RX buffer overflow. Faulty ELM327 or UART?\n");
- elm327_uart_side_failure(elm);
- break;
- } else if (len == elm->rxfill) {
- if (elm327_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;
-
- elm327_handle_prompt(elm);
- break;
- }
-
- /* No <CR> found - we haven't received a full line yet.
- * Wait for more data.
- */
- break;
- }
-
- /* We have a full line to parse. */
- elm327_parse_line(elm, len);
-
- /* Remove parsed data from RX buffer. */
- elm327_drop_bytes(elm, len + 1);
-
- /* More data to parse? */
- if (elm->rxfill)
- elm327_parse_rxbuf(elm);
- }
-}
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,10,0)
-/* Dummy needed to use can_rx_offload */
-static struct sk_buff *elmcan_mailbox_read(struct can_rx_offload *offload,
- unsigned int n, u32 *timestamp,
- bool drop)
-{
- WARN_ON_ONCE(1); /* This function is a dummy, so don't call it! */
-
- return ERR_PTR(-ENOBUFS);
-}
-#endif
-
-static int elmcan_netdev_open(struct net_device *dev)
-{
- struct elmcan *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;
- }
-
- elm327_init(elm);
- spin_unlock_bh(&elm->lock);
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,10,0)
- elm->offload.mailbox_read = elmcan_mailbox_read;
- err = can_rx_offload_add_fifo(dev, &elm->offload, ELM327_NAPI_WEIGHT);
-#else
- err = can_rx_offload_add_manual(dev, &elm->offload, ELM327_NAPI_WEIGHT);
-#endif
- if (err) {
- close_candev(dev);
- return err;
- }
-
- can_rx_offload_enable(&elm->offload);
-
- can_led_event(dev, CAN_LED_EVENT_OPEN);
- elm->can.state = CAN_STATE_ERROR_ACTIVE;
- netif_start_queue(dev);
-
- return 0;
-}
-
-static int elmcan_netdev_close(struct net_device *dev)
-{
- struct elmcan *elm = netdev_priv(dev);
-
- /* Interrupt whatever the ELM327 is doing right now */
- spin_lock_bh(&elm->lock);
- elm327_send(elm, ELM327_DUMMY_STRING, 1);
- spin_unlock_bh(&elm->lock);
-
- netif_stop_queue(dev);
-
- /* Give UART one final chance to flush. */
- clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
- flush_work(&elm->tx_work);
-
- can_rx_offload_disable(&elm->offload);
- elm->can.state = CAN_STATE_STOPPED;
- can_rx_offload_del(&elm->offload);
- close_candev(dev);
- can_led_event(dev, CAN_LED_EVENT_STOP);
-
- return 0;
-}
-
-/* Send a can_frame to a TTY. */
-static netdev_tx_t elmcan_netdev_start_xmit(struct sk_buff *skb,
- struct net_device *dev)
-{
- struct elmcan *elm = netdev_priv(dev);
- struct can_frame *frame = (struct can_frame *)skb->data;
-
- if (can_dropped_invalid_skb(dev, skb))
- return NETDEV_TX_OK;
-
- /* BHs are already disabled, so no spin_lock_bh().
- * See Documentation/networking/netdevices.txt
- */
- spin_lock(&elm->lock);
-
- /* We shouldn't get here after a hardware fault:
- * can_bus_off() calls netif_carrier_off()
- */
- WARN_ON_ONCE(elm->uart_side_failure);
-
- if (!elm->tty ||
- elm->uart_side_failure ||
- elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
- spin_unlock(&elm->lock);
- goto out;
- }
-
- netif_stop_queue(dev);
-
- elm327_send_frame(elm, frame);
- spin_unlock(&elm->lock);
-
- dev->stats.tx_packets++;
- dev->stats.tx_bytes += frame->len;
-
- can_led_event(dev, CAN_LED_EVENT_TX);
-
-out:
- kfree_skb(skb);
- return NETDEV_TX_OK;
-}
-
-static const struct net_device_ops elmcan_netdev_ops = {
- .ndo_open = elmcan_netdev_open,
- .ndo_stop = elmcan_netdev_close,
- .ndo_start_xmit = elmcan_netdev_start_xmit,
- .ndo_change_mtu = can_change_mtu,
-};
-
-static bool elmcan_is_valid_rx_char(char c)
-{
- return (isdigit(c) ||
- isupper(c) ||
- c == ELM327_DUMMY_CHAR ||
- c == ELM327_READY_CHAR ||
- c == '<' ||
- c == 'a' ||
- c == 'b' ||
- c == 'v' ||
- c == '.' ||
- c == '?' ||
- c == '\r' ||
- c == ' ');
-}
-
-/* Handle incoming ELM327 ASCII data.
- * This will not be re-entered while running, but other ldisc
- * functions may be called in parallel.
- */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
-static void elmcan_ldisc_rx(struct tty_struct *tty,
- const unsigned char *cp, char *fp, int count)
-#else
-static void elmcan_ldisc_rx(struct tty_struct *tty,
- const unsigned char *cp, const char *fp, int count)
-#endif
-{
- struct elmcan *elm = (struct elmcan *)tty->disc_data;
-
- spin_lock_bh(&elm->lock);
-
- if (elm->uart_side_failure)
- goto out;
-
- while (count-- && elm->rxfill < ELM327_SIZE_RXBUF) {
- if (fp && *fp++) {
- netdev_err(elm->dev, "Error in received character stream. Check your wiring.");
-
- elm327_uart_side_failure(elm);
-
- goto out;
- }
-
- /* 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 != 0) {
- /* Check for stray characters on the UART line.
- * Likely caused by bad hardware.
- */
- if (!elmcan_is_valid_rx_char(*cp)) {
- netdev_err(elm->dev,
- "Received illegal character %02x.\n",
- *cp);
- elm327_uart_side_failure(elm);
-
- goto out;
- }
-
- elm->rxbuf[elm->rxfill++] = *cp;
- }
-
- cp++;
- }
-
- if (count >= 0) {
- netdev_err(elm->dev, "Receive buffer overflowed. Bad chip or wiring?");
-
- elm327_uart_side_failure(elm);
-
- goto out;
- }
-
- elm327_parse_rxbuf(elm);
-
-out:
- spin_unlock_bh(&elm->lock);
-}
-
-/* Write out remaining transmit buffer.
- * Scheduled when TTY is writable.
- */
-static void elmcan_ldisc_tx_worker(struct work_struct *work)
-{
- struct elmcan *elm = container_of(work, struct elmcan, 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);
- elm327_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);
- } else {
- spin_unlock_bh(&elm->lock);
- }
-}
-
-/* Called by the driver when there's room for more data. */
-static void elmcan_ldisc_tx_wakeup(struct tty_struct *tty)
-{
- struct elmcan *elm = (struct elmcan *)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 elmcan_bitrate_const[64] = {
- 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
-};
-
-/* Dummy needed to use bitrate_const */
-static int elmcan_do_set_bittiming(struct net_device *netdev)
-{
- return 0;
-}
-
-static int elmcan_ldisc_open(struct tty_struct *tty)
-{
- struct net_device *dev;
- struct elmcan *elm;
- int err;
-
- if (!capable(CAP_NET_ADMIN))
- return -EPERM;
-
- if (!tty->ops->write)
- return -EOPNOTSUPP;
-
- dev = alloc_candev(sizeof(struct elmcan), 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, elmcan_ldisc_tx_worker);
-
- /* Configure CAN metadata */
- elm->can.bitrate_const = elmcan_bitrate_const;
- elm->can.bitrate_const_cnt = ARRAY_SIZE(elmcan_bitrate_const);
- elm->can.do_set_bittiming = elmcan_do_set_bittiming;
- elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
-
- /* Configure netdev interface */
- elm->dev = dev;
- dev->netdev_ops = &elmcan_netdev_ops;
-
- /* Mark ldisc channel as alive */
- elm->tty = tty;
- tty->disc_data = elm;
-
- devm_can_led_init(elm->dev);
-
- /* Let 'er rip */
- err = register_candev(elm->dev);
- if (err)
- goto out_err;
-
- netdev_info(elm->dev, "elmcan on %s.\n", tty->name);
-
- return 0;
-
-out_err:
- free_candev(elm->dev);
- return err;
-}
-
-/* Close down an elmcan 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 elmcan_ldisc_close(struct tty_struct *tty)
-{
- struct elmcan *elm = (struct elmcan *)tty->disc_data;
-
- /* unregister_netdev() calls .ndo_stop() so we don't have to.
- * Our .ndo_stop() also flushes the TTY write wakeup handler,
- * so we can safely set elm->tty = NULL after this.
- */
- unregister_candev(elm->dev);
-
- /* 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, "elmcan off %s.\n", tty->name);
-
- free_candev(elm->dev);
-}
-
-static int elmcan_ldisc_ioctl(struct tty_struct *tty,
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,17,0)
- struct file *file,
-#endif
- unsigned int cmd, unsigned long arg)
-{
- struct elmcan *elm = (struct elmcan *)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:
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,16,0)
- return tty_mode_ioctl(tty, file, cmd, arg);
-#else
- return tty_mode_ioctl(tty, cmd, arg);
-#endif
- }
-}
-
-static struct tty_ldisc_ops elmcan_ldisc = {
- .owner = THIS_MODULE,
- .name = "elmcan",
- .num = N_DEVELOPMENT,
- .receive_buf = elmcan_ldisc_rx,
- .write_wakeup = elmcan_ldisc_tx_wakeup,
- .open = elmcan_ldisc_open,
- .close = elmcan_ldisc_close,
- .ioctl = elmcan_ldisc_ioctl,
-};
-
-static int __init elmcan_init(void)
-{
- int status;
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
- status = tty_register_ldisc(N_DEVELOPMENT, &elmcan_ldisc);
-#else
- status = tty_register_ldisc(&elmcan_ldisc);
-#endif
- if (status)
- pr_err("Can't register line discipline\n");
-
- return status;
-}
-
-static void __exit elmcan_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.
- */
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
- int status;
-
- status = tty_unregister_ldisc(N_DEVELOPMENT);
- if (status)
- pr_err("Can't unregister line discipline (error: %d)\n",
- status);
-#else
- tty_unregister_ldisc(&elmcan_ldisc);
-#endif
-}
-
-module_init(elmcan_init);
-module_exit(elmcan_exit);
-
-MODULE_ALIAS_LDISC(N_DEVELOPMENT);
-MODULE_DESCRIPTION("ELM327 based CAN interface");
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Max Staudt <max-linux@enpas.org>");
Requirements
-------------
-This requires Linux 4.11 (for 431af779256c), and has been tested on 4.19.
+This requires Linux 4.11 (for 431af779256c) at the very least.
-Also, elmcan depends on ``can-dev``:
+Also, can327 depends on ``can-dev``:
sudo modprobe can-dev
.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
-ELM327 driver for Linux SocketCAN
-==================================
+can327: ELM327 driver for Linux SocketCAN
+==========================================
Out-of-tree version
--------------------
-This is the non-upstreamed version of the elmcan driver.
+This is the non-upstreamed version of the can327 driver.
Please see out-of-tree.rst for compilation/usage hints.
the driver has to switch between its modes as quickly as possible in
order to fake full-duplex operation.
-As such, elmcan is a best effort driver. However, this is more than
+As such, can327 is a best effort driver. However, this is more than
enough to implement simple request-response protocols (such as OBD II),
and to monitor broadcast messages on a bus (such as in a vehicle).
sending a frame, the ELM327 will be in "receive reply" mode, in
which it *does* ACK any received frames. Once the bus goes silent
or an error occurs (such as BUFFER FULL), the ELM327 will end reply
- reception mode on its own and elmcan will fall back to "``AT MA``"
+ reception mode on its own and can327 will fall back to "``AT MA``"
in order to keep monitoring the bus.
- Versions prior to 1.3
- These chips cannot be used at all with elmcan. They do not support
+ These chips cannot be used at all with can327. They do not support
the "``AT D1``" command, which is necessary to avoid parsing conflicts
on incoming data, as well as distinction of RTR frame lengths.
The init script in the driver switches off several configuration options
that are only meaningful in the original OBD scenario the chip is meant
-for, and are actually a hindrance for elmcan.
+for, and are actually a hindrance for can327.
When a command is not recognized, such as by an older version of the
?
>
-At present, elmcan does not evaluate this response and silently assumes
+At present, can327 does not evaluate this response and silently assumes
that all commands are recognized. It is structured such that it will
degrade gracefully when a command is unknown. See the sections above on
known limitations for details.
123 8 DEADBEEF12345678
For 29 bit CAN frames, the address format is slightly different, which
-elmcan uses to tell the two apart::
+can327 uses to tell the two apart::
12 34 56 78 8 DEADBEEF12345678
projects / elmcan.git / commitdiff