+// SPDX-License-Identifier: GPL-2.0
/*
* elmcan.c - ELM327 based CAN interface driver
* (tty line discipline)
*
* This file is derived from linux/drivers/net/can/slcan.c
*
- * elmcan.c Author : Max Staudt <elmcan@enpas.org>
+ * 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>
*
- * SPDX-License-Identifier: GPL-2.0
- *
*/
#define pr_fmt(fmt) "[elmcan] " fmt
#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>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Max Staudt <max-linux@enpas.org>");
+/* If this is enabled, we'll try to make the best of the situation
+ * even if we receive unexpected characters on the line.
+ * No guarantees.
+ * Handle with care, it's likely your hardware is unreliable!
+ */
+static bool accept_flaky_uart;
+module_param_named(accept_flaky_uart, accept_flaky_uart, bool, 0444);
+MODULE_PARM_DESC(accept_flaky_uart, "Don't bail at the first invalid character. Behavior undefined.");
+
+
/* Line discipline ID number */
#ifndef N_ELMCAN
#define N_ELMCAN 29
ELM_TODO_CANID_11BIT,
ELM_TODO_CANID_29BIT_LOW,
ELM_TODO_CANID_29BIT_HIGH,
+ ELM_TODO_CAN_CONFIG_PART2,
ELM_TODO_CAN_CONFIG,
ELM_TODO_RESPONSES,
ELM_TODO_SILENT_MONITOR,
struct tty_struct *tty;
struct net_device *dev;
- char ifname[IFNAMSIZ];
-
/* Per-channel lock */
spinlock_t lock;
*/
atomic_t refcount;
+ /* Stop the channel on hardware failure.
+ * Once this is true, nothing will be sent to the TTY.
+ */
+ bool hw_failure;
+
/* TTY TX helpers */
struct work_struct tx_work; /* Flushes TTY TX buffer */
unsigned char txbuf[32];
int drop_next_line;
/* The CAN frame and config the ELM327 is sending/using,
- * or will send/use after finishing all cmds_todo */
+ * or will send/use after finishing all cmds_todo
+ */
struct can_frame can_frame;
unsigned short can_config;
unsigned long can_bitrate;
static DEFINE_SPINLOCK(elmcan_discdata_lock);
+static inline void elm327_hw_failure(struct elmcan *elm);
+
/************************************************************************
{
int actual;
+ if (elm->hw_failure)
+ return;
+
memcpy(elm->txbuf, buf, len);
/* Order of next two lines is *very* important.
*/
set_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
actual = elm->tty->ops->write(elm->tty, elm->txbuf, len);
+ if (actual < 0) {
+ netdev_err(elm->dev,
+ "Failed to write to tty %s.\n",
+ elm->tty->name);
+ elm327_hw_failure(elm);
+ return;
+ }
+
elm->txleft = len - actual;
elm->txhead = elm->txbuf + actual;
}
elm327_send(elm, ELM327_MAGIC_STRING, 1);
elm->state = ELM_GETMAGICCHAR;
- elm->rxfill = 0;
}
}
/* Schedule any necessary changes in ELM327's CAN configuration */
if (elm->can_frame.can_id != frame->can_id) {
/* Set the new CAN ID for transmission. */
- if ((frame->can_id & CAN_EFF_FLAG) ^ (elm->can_frame.can_id & CAN_EFF_FLAG)) {
- elm->can_config = (frame->can_id & CAN_EFF_FLAG ? 0 : ELM327_CAN_CONFIG_SEND_SFF)
+ if ((frame->can_id & CAN_EFF_FLAG)
+ ^ (elm->can_frame.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;
* (assumes elm->lock taken) *
************************************************************************/
-static void elm327_feed_frame_to_netdev(struct elmcan *elm, const struct can_frame *frame)
+static void elm327_feed_frame_to_netdev(struct elmcan *elm,
+ const struct can_frame *frame)
{
struct can_frame *cf;
struct sk_buff *skb;
- if (!netif_running(elm->dev)) {
+ if (!netif_running(elm->dev))
return;
- }
skb = alloc_can_skb(elm->dev, &cf);
/************************************************************************
- * ELM327: Panic handler *
+ * ELM327: "Panic" handler *
* *
* (assumes elm->lock taken) *
************************************************************************/
-static inline void elm327_panic(struct elmcan *elm)
+/* Called when we're out of ideas and just want it all to end. */
+static inline void elm327_hw_failure(struct elmcan *elm)
{
- struct can_frame frame = {0};
+ struct can_frame frame;
- frame.can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED;
+ memset(&frame, 0, sizeof(frame));
+ frame.can_id = CAN_ERR_FLAG;
frame.can_dlc = CAN_ERR_DLC;
+ frame.data[5] = 'R';
+ frame.data[6] = 'I';
+ frame.data[7] = 'P';
elm327_feed_frame_to_netdev(elm, &frame);
- pr_err("ELM327 misbehaved. Re-initializing.\n");
+ netdev_err(elm->dev, "ELM327 misbehaved. Blocking further communication.\n");
- elm->can.can_stats.restarts++;
- elm327_init(elm);
+ elm->hw_failure = true;
+ can_bus_off(elm->dev);
}
* (assumes elm->lock taken) *
************************************************************************/
+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_parse_error(struct elmcan *elm, int len)
{
- struct can_frame frame = {0};
+ struct can_frame frame;
+ memset(&frame, 0, sizeof(frame));
frame.can_id = CAN_ERR_FLAG;
frame.can_dlc = CAN_ERR_DLC;
- switch(len) {
- case 17:
- if (!memcmp(elm->rxbuf, "UNABLE TO CONNECT", 17)) {
- pr_err("The ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
- }
- break;
- case 11:
- if (!memcmp(elm->rxbuf, "BUFFER FULL", 11)) {
- /* This case will only happen if the last data
- * line was complete.
- * Otherwise, elm327_parse_frame() will emit the
- * error frame instead.
- */
- frame.can_id |= CAN_ERR_CRTL;
- frame.data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
- }
- break;
- case 9:
- if (!memcmp(elm->rxbuf, "BUS ERROR", 9)) {
- frame.can_id |= CAN_ERR_BUSERROR;
- }
- if (!memcmp(elm->rxbuf, "CAN ERROR", 9)
- || !memcmp(elm->rxbuf, "<RX ERROR", 9)) {
- frame.can_id |= CAN_ERR_PROT;
- }
- break;
- case 8:
- if (!memcmp(elm->rxbuf, "BUS BUSY", 8)) {
- frame.can_id |= CAN_ERR_PROT;
- frame.data[2] = CAN_ERR_PROT_OVERLOAD;
- }
- if (!memcmp(elm->rxbuf, "FB ERROR", 8)) {
- frame.can_id |= CAN_ERR_PROT;
- frame.data[2] = CAN_ERR_PROT_TX;
- }
- break;
- case 5:
- if (!memcmp(elm->rxbuf, "ERR", 3)) {
- pr_err("The 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;
- }
- break;
- default:
- /* Don't emit an error frame if we're unsure */
- return;
+ switch (len) {
+ case 17:
+ if (!memcmp(elm->rxbuf, "UNABLE TO CONNECT", 17)) {
+ netdev_err(elm->dev,
+ "The ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
+ }
+ break;
+ case 11:
+ if (!memcmp(elm->rxbuf, "BUFFER FULL", 11)) {
+ /* This case will only happen if the last data
+ * line was complete.
+ * Otherwise, elm327_parse_frame() will emit the
+ * error frame instead.
+ */
+ frame.can_id |= CAN_ERR_CRTL;
+ frame.data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+ }
+ break;
+ case 9:
+ if (!memcmp(elm->rxbuf, "BUS ERROR", 9))
+ frame.can_id |= CAN_ERR_BUSERROR;
+ if (!memcmp(elm->rxbuf, "CAN ERROR", 9))
+ frame.can_id |= CAN_ERR_PROT;
+ if (!memcmp(elm->rxbuf, "<RX ERROR", 9))
+ frame.can_id |= CAN_ERR_PROT;
+ break;
+ case 8:
+ if (!memcmp(elm->rxbuf, "BUS BUSY", 8)) {
+ frame.can_id |= CAN_ERR_PROT;
+ frame.data[2] = CAN_ERR_PROT_OVERLOAD;
+ }
+ if (!memcmp(elm->rxbuf, "FB ERROR", 8)) {
+ frame.can_id |= CAN_ERR_PROT;
+ frame.data[2] = CAN_ERR_PROT_TX;
+ }
+ break;
+ case 5:
+ if (!memcmp(elm->rxbuf, "ERR", 3)) {
+ netdev_err(elm->dev, "The 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;
+ }
+ break;
+ default:
+ /* Don't emit an error frame if we're unsure */
+ return;
}
elm327_feed_frame_to_netdev(elm, &frame);
static int elm327_parse_frame(struct elmcan *elm, int len)
{
- struct can_frame frame = {0};
+ struct can_frame frame;
int hexlen;
int datastart;
int i;
+ memset(&frame, 0, sizeof(frame));
+
/* 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.
}
}
+ /* If we accept stray characters coming in:
+ * Check for stray characters on a payload line.
+ * No idea what causes this.
+ */
+ if (accept_flaky_uart
+ && 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.
+ */
+ elm327_kick_into_cmd_mode(elm);
+ return 3;
+ }
+
/* 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.
}
/* Is the line long enough to hold the advertised payload? */
- if (!(frame.can_id & CAN_RTR_FLAG) && (hexlen < frame.can_dlc * 3 + datastart)) {
+ if (!(frame.can_id & CAN_RTR_FLAG)
+ && (hexlen < frame.can_dlc * 3 + datastart)) {
/* Incomplete frame. */
/* Probably the ELM327's RS232 TX buffer was full.
/* Parse the data nibbles. */
for (i = 0; i < frame.can_dlc; i++) {
frame.data[i] = (hex_to_bin(elm->rxbuf[datastart+3*i]) << 4)
- | (hex_to_bin(elm->rxbuf[datastart+3*i+1]) << 0);
+ | (hex_to_bin(elm->rxbuf[datastart+3*i+1]) << 0);
}
/* Feed the frame to the network layer. */
static void elm327_parse_line(struct elmcan *elm, int len)
{
/* Skip empty lines */
- if (!len) {
+ if (!len)
return;
- }
/* Skip echo lines */
if (elm->drop_next_line) {
}
/* Regular parsing */
- switch(elm->state) {
- case ELM_RECEIVING:
- if (elm327_parse_frame(elm, len)) {
- /* Parse an error line. */
- elm327_parse_error(elm, len);
+ switch (elm->state) {
+ case ELM_RECEIVING:
+ if (elm327_parse_frame(elm, len)) {
+ /* Parse an error line. */
+ elm327_parse_error(elm, len);
- /* After the error line, we expect a prompt. */
- elm->state = ELM_GETPROMPT;
- }
- break;
- default:
- break;
+ /* Start afresh. */
+ elm327_kick_into_cmd_mode(elm);
+ }
+ break;
+ default:
+ break;
}
}
static void elm327_handle_prompt(struct elmcan *elm)
{
- if (elm->cmds_todo) {
- struct can_frame *frame = &elm->can_frame;
- char txbuf[20];
-
- if (test_bit(ELM_TODO_INIT, &elm->cmds_todo)) {
- elm327_send(elm, *elm->next_init_cmd, strlen(*elm->next_init_cmd));
- elm->next_init_cmd++;
- if (!(*elm->next_init_cmd)) {
- clear_bit(ELM_TODO_INIT, &elm->cmds_todo);
- pr_info("%s: Initialization finished.\n", elm->dev->name);
- }
+ struct can_frame *frame = &elm->can_frame;
+ char local_txbuf[20];
+
+ if (!elm->cmds_todo) {
+ /* Enter CAN monitor mode */
+ elm327_send(elm, "ATMA\r", 5);
+ elm->state = ELM_RECEIVING;
+
+ return;
+ }
+
+ /* Reconfigure ELM327 step by step as indicated by elm->cmds_todo */
+ if (test_bit(ELM_TODO_INIT, &elm->cmds_todo)) {
+ elm327_send(elm, *elm->next_init_cmd, strlen(*elm->next_init_cmd));
+ elm->next_init_cmd++;
+ if (!(*elm->next_init_cmd)) {
+ clear_bit(ELM_TODO_INIT, &elm->cmds_todo);
+ netdev_info(elm->dev, "Initialization finished.\n");
+ }
+
+ /* Some chips are unreliable and need extra time after
+ * init commands, as seen with a clone.
+ * So let's do a dummy get-cmd-prompt dance.
+ */
+ elm->state = ELM_NOTINIT;
+ elm327_kick_into_cmd_mode(elm);
- /* Some chips are unreliable and need extra time after
- * init commands, as seen with a clone.
- * So let's do a dummy get-cmd-prompt dance.
+ return;
+
+ } else if (test_and_clear_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATCSM%i\r",
+ !(!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)));
+
+ } else if (test_and_clear_bit(ELM_TODO_RESPONSES, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATR%i\r",
+ !(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
+
+ } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATPC\r");
+ set_bit(ELM_TODO_CAN_CONFIG_PART2, &elm->cmds_todo);
+
+ } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG_PART2, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATPB%04X\r",
+ elm->can_config);
+
+ } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATCP%02X\r",
+ (frame->can_id & CAN_EFF_MASK) >> 24);
+
+ } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATSH%06X\r",
+ frame->can_id & CAN_EFF_MASK & ((1 << 24) - 1));
+
+ } else if (test_and_clear_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo)) {
+ sprintf(local_txbuf, "ATSH%03X\r",
+ frame->can_id & CAN_SFF_MASK);
+
+ } else if (test_and_clear_bit(ELM_TODO_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.
*/
- elm->state = ELM_NOTINIT;
- elm327_kick_into_cmd_mode(elm);
- } else if (test_and_clear_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo)) {
- snprintf(txbuf, sizeof(txbuf), "ATCSM%i\r", !(!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)));
- } else if (test_and_clear_bit(ELM_TODO_RESPONSES, &elm->cmds_todo)) {
- snprintf(txbuf, sizeof(txbuf), "ATR%i\r", !(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
- } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo)) {
- snprintf(txbuf, sizeof(txbuf), "ATPB%04X\r", elm->can_config);
- } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo)) {
- snprintf(txbuf, sizeof(txbuf), "ATCP%02X\r", (frame->can_id & CAN_EFF_MASK) >> 24);
- } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo)) {
- snprintf(txbuf, sizeof(txbuf), "ATSH%06X\r", frame->can_id & CAN_EFF_MASK & ((1 << 24) - 1));
- } else if (test_and_clear_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo)) {
- snprintf(txbuf, sizeof(txbuf), "ATSH%03X\r", frame->can_id & CAN_SFF_MASK);
- } else if (test_and_clear_bit(ELM_TODO_CAN_DATA, &elm->cmds_todo)) {
- if (frame->can_id & CAN_RTR_FLAG) {
- snprintf(txbuf, sizeof(txbuf), "ATRTR\r");
- } else {
- int i;
-
- for (i = 0; i < frame->can_dlc; i++) {
- sprintf(&txbuf[2*i], "%02X", frame->data[i]);
- }
-
- sprintf(&txbuf[2*i], "\r");
+ sprintf(local_txbuf, "ATRTR\r");
+ } else {
+ /* Send a regular CAN data frame */
+ int i;
+
+ for (i = 0; i < frame->can_dlc; i++) {
+ sprintf(&local_txbuf[2*i], "%02X",
+ frame->data[i]);
}
- elm->drop_next_line = 1;
- elm->state = ELM_RECEIVING;
+ sprintf(&local_txbuf[2*i], "\r");
}
- elm327_send(elm, txbuf, strlen(txbuf));
- } else {
- /* Enter CAN monitor mode */
- elm327_send(elm, "ATMA\r", 5);
+ elm->drop_next_line = 1;
elm->state = ELM_RECEIVING;
}
+
+ elm327_send(elm, local_txbuf, strlen(local_txbuf));
}
elm->state = ELM_GETPROMPT;
i++;
break;
- } else if (elm->rxbuf[i] == ELM327_READY_CHAR) {
+ } else if (elm327_is_ready_char(elm->rxbuf[i])) {
elm327_send(elm, ELM327_MAGIC_STRING, 1);
i++;
break;
case ELM_GETPROMPT:
/* Wait for '>' */
- if (elm->rxbuf[elm->rxfill - 1] == ELM327_READY_CHAR) {
+ if (elm327_is_ready_char(elm->rxbuf[elm->rxfill - 1]))
elm327_handle_prompt(elm);
- }
elm->rxfill = 0;
return;
/* Line exceeds buffer. It's probably all garbage.
* Did we even connect at the right baud rate?
*/
- pr_err("RX buffer overflow. Faulty ELM327 connected?\n");
- elm327_panic(elm);
+ netdev_err(elm->dev,
+ "RX buffer overflow. Faulty ELM327 or UART?\n");
+ elm327_hw_failure(elm);
+ return;
} else if (len == elm->rxfill) {
- if (elm->state == ELM_RECEIVING
- && elm->rxbuf[elm->rxfill - 1] == ELM327_READY_CHAR) {
+ 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.
elm327_handle_prompt(elm);
return;
- } else {
- /* We haven't received a full line yet.
- * Wait for more data.
- */
- return;
}
+
+ /* No <CR> found - we haven't received a full line yet.
+ * Wait for more data.
+ */
+ return;
}
/* We have a full line to parse. */
elm327_drop_bytes(elm, len+1);
/* More data to parse? */
- if (elm->rxfill) {
+ if (elm->rxfill)
elm327_parse_rxbuf(elm);
- }
}
}
* (takes elm->lock) *
************************************************************************/
-static int elmcan_netdev_init(struct net_device *dev)
-{
- struct elmcan *elm = netdev_priv(dev);
-
- /* Copy the interface name here, so the SIOCGIFNAME case in
- * elmcan_ldisc_ioctl() doesn't race against unregister_candev().
- */
- memcpy(elm->ifname, dev->name, IFNAMSIZ);
-
- return 0;
-}
-
/* Netdevice DOWN -> UP routine */
static int elmcan_netdev_open(struct net_device *dev)
{
int err;
spin_lock_bh(&elm->lock);
+ if (elm->hw_failure) {
+ netdev_err(elm->dev, "Refusing to open interface after a hardware fault has been detected.\n");
+ spin_unlock_bh(&elm->lock);
+ return -EIO;
+ }
+
if (elm->tty == NULL) {
spin_unlock_bh(&elm->lock);
return -ENODEV;
}
/* Send a can_frame to a TTY queue. */
-static netdev_tx_t elmcan_netdev_start_xmit(struct sk_buff *skb, struct net_device *dev)
+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;
goto out;
if (!netif_running(dev)) {
- pr_warn("%s: xmit: iface is down\n", dev->name);
+ netdev_warn(elm->dev, "xmit: iface is down.\n");
goto out;
}
* 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()
+ */
+ BUG_ON(elm->hw_failure);
+
if (elm->tty == NULL
|| elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
spin_unlock(&elm->lock);
}
static const struct net_device_ops elmcan_netdev_ops = {
- .ndo_init = elmcan_netdev_init,
.ndo_open = elmcan_netdev_open,
.ndo_stop = elmcan_netdev_close,
.ndo_start_xmit = elmcan_netdev_start_xmit,
* This is to ensure ordering in case we are shutting down, and to ensure
* there is a refcount at all (because tty->disc_data may be NULL).
*/
-static struct elmcan* get_elm(struct tty_struct *tty)
+static struct elmcan *get_elm(struct tty_struct *tty)
{
struct elmcan *elm;
bool got_ref;
got_ref = atomic_inc_not_zero(&elm->refcount);
spin_unlock_bh(&elmcan_discdata_lock);
- if (!got_ref) {
+ if (!got_ref)
return NULL;
- }
return elm;
}
if (!elm)
return;
+ spin_lock_bh(&elm->lock);
+ if (elm->hw_failure) {
+ spin_unlock_bh(&elm->lock);
+
+ put_elm(elm);
+ return;
+ }
+
/* Read the characters out of the buffer */
while (count-- && elm->rxfill < sizeof(elm->rxbuf)) {
if (fp && *fp++) {
- pr_err("Error in received character stream. Check your wiring.");
+ netdev_err(elm->dev, "Error in received character stream. Check your wiring.");
- spin_lock_bh(&elm->lock);
- elm327_panic(elm);
+ elm327_hw_failure(elm);
spin_unlock_bh(&elm->lock);
put_elm(elm);
return;
}
+
+ /* 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.
+ * No idea what causes this.
+ */
+ if (!accept_flaky_uart
+ && !isdigit(*cp)
+ && !isupper(*cp)
+ && ELM327_MAGIC_CHAR != *cp
+ && ELM327_READY_CHAR != *cp
+ && '<' != *cp
+ && 'a' != *cp
+ && 'b' != *cp
+ && 'v' != *cp
+ && '.' != *cp
+ && '?' != *cp
+ && '\r' != *cp
+ && ' ' != *cp) {
+ /* We've received an invalid character, so bail.
+ * There's something wrong with the ELM327, or
+ * with the UART line.
+ */
+ netdev_err(elm->dev,
+ "Received illegal character %02x.\n",
+ *cp);
+ elm327_hw_failure(elm);
+ spin_unlock_bh(&elm->lock);
+
+ put_elm(elm);
+ return;
+ }
+
elm->rxbuf[elm->rxfill++] = *cp;
}
+
cp++;
}
if (count >= 0) {
- pr_err("Receive buffer overflowed. Bad chip or wiring?");
+ netdev_err(elm->dev, "Receive buffer overflowed. Bad chip or wiring?");
- spin_lock_bh(&elm->lock);
- elm327_panic(elm);
+ elm327_hw_failure(elm);
spin_unlock_bh(&elm->lock);
put_elm(elm);
return;
}
- spin_lock_bh(&elm->lock);
elm327_parse_rxbuf(elm);
spin_unlock_bh(&elm->lock);
ssize_t actual;
spin_lock_bh(&elm->lock);
- /* First make sure we're connected. */
+ if (elm->hw_failure) {
+ spin_unlock_bh(&elm->lock);
+ return;
+ }
+
if (!elm->tty || !netif_running(elm->dev)) {
spin_unlock_bh(&elm->lock);
return;
actual = elm->tty->ops->write(elm->tty, elm->txhead, elm->txleft);
if (actual < 0) {
- pr_err("Failed to write to tty for %s.\n", elm->dev->name);
- elm327_panic(elm);
+ netdev_err(elm->dev,
+ "Failed to write to tty %s.\n",
+ elm->tty->name);
+ elm327_hw_failure(elm);
+ spin_unlock_bh(&elm->lock);
+ return;
}
elm->txleft -= actual;
-/* Some fake bit timings to allow bitrate setting */
-static const struct can_bittiming_const elmcan_bittiming_const = {
- .name = "elmcan",
- .tseg1_min = 1,
- .tseg1_max = 1,
- .tseg2_min = 0,
- .tseg2_max = 0,
- .sjw_max = 1,
- .brp_min = 1,
- .brp_max = 500,
- .brp_inc = 1,
+/* 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 function to claim we're changing the bitrate.
+ * We actually do this when opening the net device.
+ */
+static int elmcan_do_set_bittiming(struct net_device *netdev)
+{
+ return 0;
+}
+
+
/*
* Open the high-level part of the elmcan channel.
* This function is called by the TTY module when the
/* Configure CAN metadata */
elm->can.state = CAN_STATE_STOPPED;
- elm->can.clock.freq = 1000000;
- elm->can.bittiming_const = &elmcan_bittiming_const;
+ 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 netlink interface */
put_elm(elm);
/* Spin until refcount reaches 0 */
- while(atomic_read(&elm->refcount) > 0)
- msleep(1);
+ while (atomic_read(&elm->refcount) > 0)
+ msleep_interruptible(10);
/* At this point, all ldisc calls to us will be no-ops.
* Since the refcount is 0, they are bailing immediately.
struct elmcan *elm = get_elm(tty);
unsigned int tmp;
- /* First make sure we're connected. */
if (!elm)
return -EINVAL;
switch (cmd) {
case SIOCGIFNAME:
- tmp = strlen(elm->ifname) + 1;
- if (copy_to_user((void __user *)arg, elm->ifname, tmp)) {
+ tmp = strnlen(elm->dev->name, IFNAMSIZ - 1) + 1;
+ if (copy_to_user((void __user *)arg, elm->dev->name, tmp)) {
put_elm(elm);
return -EFAULT;
}
/* Fill in our line protocol discipline, and register it */
status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc);
- if (status) {
+ if (status)
pr_err("can't register line discipline\n");
- }
+
return status;
}
int status;
status = tty_unregister_ldisc(N_ELMCAN);
- if (status) {
- pr_err("Can't unregister line discipline (error: %d)\n", status);
- }
+ if (status)
+ pr_err("Can't unregister line discipline (error: %d)\n",
+ status);
}
module_init(elmcan_init);