// SPDX-License-Identifier: GPL-2.0
-/* elmcan.c - ELM327 based CAN interface driver
- * (tty line discipline)
+/* 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.
+ * and my thanks go to the original authors for their inspiration, even
+ * after almost none of their code is left.
*
* 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>
- *
- * This code barely bears any resemblance to slcan anymore, and whatever
- * may be left is Linux specific boilerplate anyway, however I am leaving
- * the GPL-2.0 identifier at the top just to be sure.
- *
- * Please feel free to use my own code, especially the ELM327 communication
- * logic, in accordance with SPDX-License-Identifier BSD-3-Clause to port
- * this driver to other systems.
- * - Max
- *
*/
-#define pr_fmt(fmt) "[elmcan] " fmt
+#define pr_fmt(fmt) "elmcan: " fmt
#include <linux/init.h>
#include <linux/module.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>
-MODULE_ALIAS_LDISC(N_ELMCAN);
-MODULE_DESCRIPTION("ELM327 based CAN interface");
-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!
+/* Line discipline ID number.
+ * N_DEVELOPMENT will likely be defined from Linux 5.18 onwards:
+ * https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git/commit/?h=tty-next&id=c2faf737abfb10f88f2d2612d573e9edc3c42c37
*/
-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.");
+#ifndef N_DEVELOPMENT
+#define N_DEVELOPMENT 29
+#endif
-/* Line discipline ID number */
-#ifndef N_ELMCAN
-#define N_ELMCAN 29
+/* 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_CAN_CONFIG_RECV_BOTH_SFF_EFF 0x2000
#define ELM327_CAN_CONFIG_BAUDRATE_MULT_8_7 0x1000
-#define ELM327_MAGIC_CHAR 'y'
-#define ELM327_MAGIC_STRING "y"
+#define ELM327_DUMMY_CHAR 'y'
+#define ELM327_DUMMY_STRING "y"
#define ELM327_READY_CHAR '>'
/* Bits in elm->cmds_todo */
-enum ELM_TODO {
- TODO_CAN_DATA = 0,
- TODO_CANID_11BIT,
- TODO_CANID_29BIT_LOW,
- TODO_CANID_29BIT_HIGH,
- TODO_CAN_CONFIG_PART2,
- TODO_CAN_CONFIG,
- TODO_RESPONSES,
- TODO_SILENT_MONITOR,
- TODO_INIT
+enum ELM327_TX_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 {
struct can_rx_offload offload;
/* TTY and netdev devices that we're bridging */
- struct tty_struct *tty;
- struct net_device *dev;
+ struct tty_struct *tty;
+ struct net_device *dev;
/* Per-channel lock */
- spinlock_t lock;
-
- /* Keep track of how many things are using this struct.
- * Once it reaches 0, we are in the process of cleaning up,
- * and new operations will be cancelled immediately.
- * Use atomic_t rather than refcount_t because we deliberately
- * decrement to 0, and refcount_dec() spills a WARN_ONCE in
- * that case.
- */
- atomic_t refcount;
+ spinlock_t lock;
/* Stop the channel on hardware failure.
* Once this is true, nothing will be sent to the TTY.
*/
- bool hw_failure;
+ bool hw_failure;
/* TTY TX helpers */
- struct work_struct tx_work; /* Flushes TTY TX buffer */
- unsigned char *txbuf;
- unsigned char *txhead; /* Pointer to next TX byte */
- int txleft; /* Bytes left to TX */
+ struct work_struct tx_work; /* Flushes TTY TX buffer */
+ u8 *txbuf; /* Pointer to our TX buffer */
+ u8 *txhead; /* Pointer to next TX byte */
+ unsigned txleft; /* Bytes left to TX */
/* TTY RX helpers */
- unsigned char rxbuf[ELM327_SIZE_RXBUF];
+ u8 rxbuf[ELM327_SIZE_RXBUF];
int rxfill;
/* State machine */
enum {
- ELM_NOTINIT = 0,
- ELM_GETMAGICCHAR,
- ELM_GETPROMPT,
- ELM_RECEIVING,
+ ELM327_STATE_NOTINIT = 0,
+ ELM327_STATE_GETDUMMYCHAR,
+ ELM327_STATE_GETPROMPT,
+ ELM327_STATE_RECEIVING,
} state;
- int drop_next_line;
+ bool drop_next_line;
/* The CAN frame and config the ELM327 is sending/using,
* or will send/use after finishing all cmds_todo
*/
- struct can_frame can_frame;
- unsigned short can_config;
- unsigned long can_bitrate;
- unsigned char can_bitrate_divisor;
- int silent_monitoring;
+ struct can_frame can_frame_to_send;
+ u16 can_config;
+ u8 can_bitrate_divisor;
/* Things we have yet to send */
char **next_init_cmd;
unsigned long cmds_todo;
};
-/* A lock for all tty->disc_data handled by this ldisc.
- * This is to prevent a case where tty->disc_data is set to NULL,
- * yet someone is still trying to dereference it.
- * Without this, we cannot do a clean shutdown.
- */
-static DEFINE_SPINLOCK(elmcan_discdata_lock);
-
static inline void elm327_hw_failure(struct elmcan *elm);
- /***********************************************************************
- * ELM327: Transmission *
- * *
- * (all functions assume elm->lock taken) *
- ***********************************************************************/
-
static void elm327_send(struct elmcan *elm, const void *buf, size_t len)
{
- int actual;
+ int written;
+
+ lockdep_assert_held(elm->lock);
if (elm->hw_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);
- actual = elm->tty->ops->write(elm->tty, elm->txbuf, len);
- if (actual < 0) {
+ 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);
return;
}
- elm->txleft = len - actual;
- elm->txhead = elm->txbuf + actual;
+ elm->txleft = len - written;
+ elm->txhead = elm->txbuf + written;
+
+ if (!elm->txleft)
+ netif_wake_queue(elm->dev);
+ else
+ set_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
}
/* Take the ELM327 out of almost any state and back into command mode.
- * We send ELM327_MAGIC_CHAR which will either abort any running
+ * 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)
{
- if (elm->state != ELM_GETMAGICCHAR && elm->state != ELM_GETPROMPT) {
- elm327_send(elm, ELM327_MAGIC_STRING, 1);
+ 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 = ELM_GETMAGICCHAR;
+ 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.can_id != frame->can_id) {
+ 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.can_id & CAN_EFF_FLAG)) {
+ 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_RECV_BOTH_SFF_EFF
| elm->can_bitrate_divisor;
- set_bit(TODO_CAN_CONFIG, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo);
}
if (frame->can_id & CAN_EFF_FLAG) {
- clear_bit(TODO_CANID_11BIT, &elm->cmds_todo);
- set_bit(TODO_CANID_29BIT_LOW, &elm->cmds_todo);
- set_bit(TODO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ 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(TODO_CANID_11BIT, &elm->cmds_todo);
- clear_bit(TODO_CANID_29BIT_LOW, &elm->cmds_todo);
- clear_bit(TODO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ 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 = *frame;
- set_bit(TODO_CAN_DATA, &elm->cmds_todo);
+ elm->can_frame_to_send = *frame;
+ set_bit(ELM327_TX_DO_CAN_DATA, &elm->cmds_todo);
elm327_kick_into_cmd_mode(elm);
}
- /***********************************************************************
- * ELM327: Initialization sequence *
- * *
- * (assumes elm->lock taken) *
- ***********************************************************************/
-
+/* ELM327 initialisation sequence. */
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 Initialization */
+ "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 */
static void elm327_init(struct elmcan *elm)
{
- elm->state = ELM_NOTINIT;
- elm->can_frame.can_id = 0x7df;
+ 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;
/* Configure ELM327 and then start monitoring */
elm->next_init_cmd = &elm327_init_script[0];
- set_bit(TODO_INIT, &elm->cmds_todo);
- set_bit(TODO_SILENT_MONITOR, &elm->cmds_todo);
- set_bit(TODO_RESPONSES, &elm->cmds_todo);
- set_bit(TODO_CAN_CONFIG, &elm->cmds_todo);
+ 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);
}
- /***********************************************************************
- * ELM327: Reception -> netdev glue *
- * *
- * (assumes elm->lock taken) *
- ***********************************************************************/
-
static void elm327_feed_frame_to_netdev(struct elmcan *elm,
- const struct can_frame *frame)
+ struct sk_buff *skb)
{
- struct can_frame *cf;
- struct sk_buff *skb;
+ lockdep_assert_held(elm->lock);
if (!netif_running(elm->dev))
return;
- skb = alloc_can_skb(elm->dev, &cf);
-
- if (!skb)
- return;
-
- memcpy(cf, frame, sizeof(struct can_frame));
-
/* Queue for NAPI pickup.
* rx-offload will update stats and LEDs for us.
*/
#endif
}
- /***********************************************************************
- * ELM327: "Panic" handler *
- * *
- * (assumes elm->lock taken) *
- ***********************************************************************/
-
/* 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;
-
- 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);
+ struct can_frame *frame;
+ struct sk_buff *skb;
- netdev_err(elm->dev, "ELM327 misbehaved. Blocking further communication.\n");
+ lockdep_assert_held(elm->lock);
elm->hw_failure = true;
+
+ 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);
}
- /***********************************************************************
- * ELM327: Reception parser *
- * *
- * (assumes elm->lock taken) *
- ***********************************************************************/
+/* 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);
-static void elm327_parse_error(struct elmcan *elm, int len)
+ 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 can_frame *frame;
+ struct sk_buff *skb;
- memset(&frame, 0, sizeof(frame));
- frame.can_id = CAN_ERR_FLAG;
- frame.can_dlc = CAN_ERR_DLC;
+ lockdep_assert_held(elm->lock);
- switch (len) {
- case 17:
- if (!memcmp(elm->rxbuf, "UNABLE TO CONNECT", 17)) {
- netdev_err(elm->dev,
- "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 heuristically
- * emit this 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, "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 */
+ 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, &frame);
+ elm327_feed_frame_to_netdev(elm, skb);
}
/* Parse CAN frames coming as ASCII from ELM327.
*
* We will use the spaces and line length to guess the format.
*/
-static int elm327_parse_frame(struct elmcan *elm, int len)
+static int elm327_parse_frame(struct elmcan *elm, size_t len)
{
- struct can_frame frame;
+ struct can_frame *frame;
+ struct sk_buff *skb;
int hexlen;
int datastart;
int i;
- memset(&frame, 0, sizeof(frame));
+ 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.
}
}
- /* If we accept stray characters coming in:
- * Check for stray characters on a payload line.
- * No idea what causes this.
+ /* Sanity check whether the line is really a clean hexdump,
+ * or terminated by an error message, or contains garbage.
*/
- if (accept_flaky_uart &&
- hexlen < len &&
+ if (hexlen < len &&
!isdigit(elm->rxbuf[hexlen]) &&
!isupper(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 -ENODATA;
}
if (elm->rxbuf[2] == ' ' && elm->rxbuf[5] == ' ' &&
elm->rxbuf[8] == ' ' && elm->rxbuf[11] == ' ' &&
elm->rxbuf[13] == ' ') {
- frame.can_id = CAN_EFF_FLAG;
+ frame->can_id = CAN_EFF_FLAG;
datastart = 14;
} else if (elm->rxbuf[3] == ' ' && elm->rxbuf[5] == ' ') {
- frame.can_id = 0;
datastart = 6;
} else {
/* This is not a well-formatted data line.
*/
/* Read CAN data length */
- frame.can_dlc = (hex_to_bin(elm->rxbuf[datastart - 2]) << 0);
+ 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);
+ 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);
+ 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;
+ 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.can_dlc * 3 + datastart)) {
- /* Incomplete frame. */
-
- /* Probably the ELM327's RS232 TX buffer was full.
+ 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.can_dlc = CAN_ERR_DLC;
- frame.data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
- elm327_feed_frame_to_netdev(elm, &frame);
+ 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.
}
/* 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]));
+ 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, &frame);
+ elm327_feed_frame_to_netdev(elm, skb);
return 0;
}
-static void elm327_parse_line(struct elmcan *elm, int len)
+static void elm327_parse_line(struct elmcan *elm, size_t len)
{
+ lockdep_assert_held(elm->lock);
+
/* Skip empty lines */
if (!len)
return;
if (elm->drop_next_line) {
elm->drop_next_line = 0;
return;
- } else if (elm->rxbuf[0] == 'A' && elm->rxbuf[1] == 'T') {
+ } else if (!memcmp(elm->rxbuf, "AT", 2)) {
return;
}
/* Regular parsing */
- switch (elm->state) {
- case ELM_RECEIVING:
- if (elm327_parse_frame(elm, len)) {
- /* Parse an error line. */
- elm327_parse_error(elm, len);
+ 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);
- }
- break;
- default:
- break;
+ /* Start afresh. */
+ elm327_kick_into_cmd_mode(elm);
}
}
static void elm327_handle_prompt(struct elmcan *elm)
{
- struct can_frame *frame = &elm->can_frame;
+ struct can_frame *frame = &elm->can_frame_to_send;
char local_txbuf[20];
+ lockdep_assert_held(elm->lock);
+
if (!elm->cmds_todo) {
/* Enter CAN monitor mode */
elm327_send(elm, "ATMA\r", 5);
- elm->state = ELM_RECEIVING;
+ elm->state = ELM327_STATE_RECEIVING;
return;
}
/* Reconfigure ELM327 step by step as indicated by elm->cmds_todo */
- if (test_bit(TODO_INIT, &elm->cmds_todo)) {
+ if (test_bit(ELM327_TX_DO_INIT, &elm->cmds_todo)) {
strcpy(local_txbuf, *elm->next_init_cmd);
elm->next_init_cmd++;
if (!(*elm->next_init_cmd)) {
- clear_bit(TODO_INIT, &elm->cmds_todo);
- netdev_info(elm->dev, "Initialization finished.\n");
+ clear_bit(ELM327_TX_DO_INIT, &elm->cmds_todo);
+ /* Init finished. */
}
- } else if (test_and_clear_bit(TODO_SILENT_MONITOR, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_SILENT_MONITOR, &elm->cmds_todo)) {
sprintf(local_txbuf, "ATCSM%i\r",
!(!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)));
- } else if (test_and_clear_bit(TODO_RESPONSES, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_RESPONSES, &elm->cmds_todo)) {
sprintf(local_txbuf, "ATR%i\r",
!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
- } else if (test_and_clear_bit(TODO_CAN_CONFIG, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo)) {
sprintf(local_txbuf, "ATPC\r");
- set_bit(TODO_CAN_CONFIG_PART2, &elm->cmds_todo);
+ set_bit(ELM327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo);
- } else if (test_and_clear_bit(TODO_CAN_CONFIG_PART2, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo)) {
sprintf(local_txbuf, "ATPB%04X\r",
elm->can_config);
- } else if (test_and_clear_bit(TODO_CANID_29BIT_HIGH, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_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(TODO_CANID_29BIT_LOW, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_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(TODO_CANID_11BIT, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(ELM327_TX_DO_CANID_11BIT, &elm->cmds_todo)) {
sprintf(local_txbuf, "ATSH%03X\r",
frame->can_id & CAN_SFF_MASK);
- } else if (test_and_clear_bit(TODO_CAN_DATA, &elm->cmds_todo)) {
+ } 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.
/* Send a regular CAN data frame */
int i;
- for (i = 0; i < frame->can_dlc; i++) {
+ for (i = 0; i < frame->len; i++) {
sprintf(&local_txbuf[2 * i], "%02X",
frame->data[i]);
}
}
elm->drop_next_line = 1;
- elm->state = ELM_RECEIVING;
+ elm->state = ELM327_STATE_RECEIVING;
}
elm327_send(elm, local_txbuf, strlen(local_txbuf));
return (c & 0x3f) == ELM327_READY_CHAR;
}
-static void elm327_drop_bytes(struct elmcan *elm, int i)
+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)
{
- int len;
+ size_t len;
+ int i;
+
+ lockdep_assert_held(elm->lock);
switch (elm->state) {
- case ELM_NOTINIT:
+ case ELM327_STATE_NOTINIT:
elm->rxfill = 0;
break;
- case ELM_GETMAGICCHAR:
+ case ELM327_STATE_GETDUMMYCHAR:
{
/* Wait for 'y' or '>' */
- int i;
-
for (i = 0; i < elm->rxfill; i++) {
- if (elm->rxbuf[i] == ELM327_MAGIC_CHAR) {
+ if (elm->rxbuf[i] == ELM327_DUMMY_CHAR) {
elm327_send(elm, "\r", 1);
- elm->state = ELM_GETPROMPT;
+ elm->state = ELM327_STATE_GETPROMPT;
i++;
break;
} else if (elm327_is_ready_char(elm->rxbuf[i])) {
- elm327_send(elm, ELM327_MAGIC_STRING, 1);
+ elm327_send(elm, ELM327_DUMMY_STRING, 1);
i++;
break;
}
break;
}
- case ELM_GETPROMPT:
+ 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 ELM_RECEIVING:
+ case ELM327_STATE_RECEIVING:
/* Find <CR> delimiting feedback lines. */
for (len = 0;
(len < elm->rxfill) && (elm->rxbuf[len] != '\r');
}
}
- /***********************************************************************
- * netdev *
- * *
- * (takes elm->lock) *
- ***********************************************************************/
-
+#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,
return ERR_PTR(-ENOBUFS);
}
+#endif
static int elmcan_netdev_open(struct net_device *dev)
{
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;
spin_lock_bh(&elm->lock);
if (elm->tty) {
/* Interrupt whatever we're doing right now */
- elm327_send(elm, ELM327_MAGIC_STRING, 1);
+ elm327_send(elm, ELM327_DUMMY_STRING, 1);
/* Clear the wakeup bit, as the netdev will be down and thus
* the wakeup handler won't clear it
struct elmcan *elm = netdev_priv(dev);
struct can_frame *frame = (struct can_frame *)skb->data;
- if (skb->len != sizeof(struct can_frame))
- goto out;
-
- if (!netif_running(dev)) {
- netdev_warn(elm->dev, "xmit: iface is down.\n");
- goto out;
- }
+ 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_unlock(&elm->lock);
dev->stats.tx_packets++;
- dev->stats.tx_bytes += frame->can_dlc;
+ dev->stats.tx_bytes += frame->len;
can_led_event(dev, CAN_LED_EVENT_TX);
.ndo_change_mtu = can_change_mtu,
};
- /***********************************************************************
- * Line discipline *
- * *
- * (takes elm->lock) *
- ***********************************************************************/
-
-/* Get a reference to our struct, taking into account locks/refcounts.
- * This is to ensure ordering in case we are shutting down, and to ensure
- * there is a refcount at all (otherwise tty->disc_data may be freed and
- * before we increment the refcount).
- * Use this for anything that can race against elmcan_ldisc_close().
- */
-static struct elmcan *get_elm(struct tty_struct *tty)
-{
- struct elmcan *elm;
- bool got_ref;
-
- spin_lock_bh(&elmcan_discdata_lock);
- elm = (struct elmcan *)tty->disc_data;
-
- if (!elm) {
- spin_unlock_bh(&elmcan_discdata_lock);
- return NULL;
- }
-
- got_ref = atomic_inc_not_zero(&elm->refcount);
- spin_unlock_bh(&elmcan_discdata_lock);
-
- if (!got_ref)
- return NULL;
-
- return elm;
-}
-
-static void put_elm(struct elmcan *elm)
-{
- atomic_dec(&elm->refcount);
-}
-
static bool elmcan_is_valid_rx_char(char c)
{
- return (accept_flaky_uart ||
- isdigit(c) ||
+ return (isdigit(c) ||
isupper(c) ||
- c == ELM327_MAGIC_CHAR ||
+ c == ELM327_DUMMY_CHAR ||
c == ELM327_READY_CHAR ||
c == '<' ||
c == 'a' ||
* 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 = get_elm(tty);
-
- if (!elm)
- return;
+ struct elmcan *elm = (struct elmcan *)tty->disc_data;
spin_lock_bh(&elm->lock);
out:
spin_unlock_bh(&elm->lock);
- put_elm(elm);
}
/* Write out remaining transmit buffer.
*/
static void elmcan_ldisc_tx_worker(struct work_struct *work)
{
- /* No need to use get_elm() here, as we'll always flush workers
- * before destroying the elmcan object.
- */
struct elmcan *elm = container_of(work, struct elmcan, tx_work);
- ssize_t actual;
+ ssize_t written;
- spin_lock_bh(&elm->lock);
- if (elm->hw_failure) {
- spin_unlock_bh(&elm->lock);
+ if (elm->hw_failure)
return;
- }
- if (!elm->tty || !netif_running(elm->dev)) {
- spin_unlock_bh(&elm->lock);
- 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_hw_failure(elm);
+ spin_unlock_bh(&elm->lock);
+ return;
+ } else {
+ elm->txleft -= written;
+ elm->txhead += written;
+ }
}
- if (elm->txleft <= 0) {
- /* Our TTY write buffer is empty:
- * Allow netdev to hand us another packet
- */
+ if (!elm->txleft) {
clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
spin_unlock_bh(&elm->lock);
netif_wake_queue(elm->dev);
- return;
- }
-
- actual = elm->tty->ops->write(elm->tty, elm->txhead, elm->txleft);
- if (actual < 0) {
- netdev_err(elm->dev,
- "Failed to write to tty %s.\n",
- elm->tty->name);
- elm327_hw_failure(elm);
+ } else {
spin_unlock_bh(&elm->lock);
- return;
}
-
- elm->txleft -= actual;
- elm->txhead += actual;
- 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 = get_elm(tty);
-
- if (!elm)
- return;
+ struct elmcan *elm = (struct elmcan *)tty->disc_data;
schedule_work(&elm->tx_work);
-
- put_elm(elm);
}
/* ELM327 can only handle bitrates that are integer divisors of 500 kHz,
/* Dummy needed to use bitrate_const */
static int elmcan_do_set_bittiming(struct net_device *netdev)
{
- (void)netdev;
-
return 0;
}
tty->receive_room = 65536; /* We don't flow control */
elm->txleft = 0; /* Clear TTY TX buffer */
spin_lock_init(&elm->lock);
- atomic_set(&elm->refcount, 1);
INIT_WORK(&elm->tx_work, elmcan_ldisc_tx_worker);
/* Configure CAN metadata */
- elm->can.state = CAN_STATE_STOPPED;
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 */
+ /* Configure netdev interface */
elm->dev = dev;
dev->netdev_ops = &elmcan_netdev_ops;
*/
static void elmcan_ldisc_close(struct tty_struct *tty)
{
- struct elmcan *elm = get_elm(tty);
-
- if (!elm)
- return;
+ struct elmcan *elm = (struct elmcan *)tty->disc_data;
/* unregister_netdev() calls .ndo_stop() so we don't have to. */
unregister_candev(elm->dev);
- /* Decrease the refcount twice, once for our own get_elm(),
- * and once to remove the count of 1 that we set in _open().
- * Once it reaches 0, we can safely destroy it.
- */
- put_elm(elm);
- put_elm(elm);
-
- while (atomic_read(&elm->refcount) > 0)
- msleep_interruptible(10);
-
- /* At this point, all ldisc calls to us have become no-ops. */
-
+ /* Ensure that our worker won't be rescheduled */
+ clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
flush_work(&elm->tx_work);
/* Mark channel as dead */
free_candev(elm->dev);
}
-static int elmcan_ldisc_hangup(struct tty_struct *tty)
-{
- elmcan_ldisc_close(tty);
- return 0;
-}
-
-static int elmcan_ldisc_ioctl(struct tty_struct *tty, struct file *file,
+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 = get_elm(tty);
+ struct elmcan *elm = (struct elmcan *)tty->disc_data;
unsigned int tmp;
- if (!elm)
- return -EINVAL;
-
switch (cmd) {
case SIOCGIFNAME:
tmp = strnlen(elm->dev->name, IFNAMSIZ - 1) + 1;
- if (copy_to_user((void __user *)arg, elm->dev->name, tmp)) {
- put_elm(elm);
+ if (copy_to_user((void __user *)arg, elm->dev->name, tmp))
return -EFAULT;
- }
-
- put_elm(elm);
return 0;
case SIOCSIFHWADDR:
- put_elm(elm);
return -EINVAL;
default:
- put_elm(elm);
+#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,
- .hangup = elmcan_ldisc_hangup,
.ioctl = elmcan_ldisc_ioctl,
};
{
int status;
- pr_info("ELM327 based best-effort CAN interface driver\n");
- pr_info("This device is severely limited as a CAN interface, see documentation.\n");
-
- status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc);
+#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");
/* 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_ELMCAN);
+ 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>");
projects / elmcan.git / blobdiff