// SPDX-License-Identifier: GPL-2.0
-/*
- * elmcan.c - ELM327 based CAN interface driver
+/* elmcan.c - ELM327 based CAN interface driver
* (tty line discipline)
*
- * This file is derived from linux/drivers/net/can/slcan.c
+ * 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>
*
+ * 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
-
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/tty.h>
+#include <linux/version.h>
#include <linux/workqueue.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_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
#endif
+#define ELM327_NAPI_WEIGHT 4
+
+#define ELM327_SIZE_RXBUF 256
+#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_MAGIC_STRING "y"
#define ELM327_READY_CHAR '>'
-
/* Bits in elm->cmds_todo */
enum ELM_TODO {
- ELM_TODO_CAN_DATA = 0,
- 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,
- ELM_TODO_INIT
+ 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
};
-
struct elmcan {
/* This must be the first member when using alloc_candev() */
struct can_priv can;
+ struct can_rx_offload offload;
+
/* TTY and netdev devices that we're bridging */
struct tty_struct *tty;
struct net_device *dev;
/* TTY TX helpers */
struct work_struct tx_work; /* Flushes TTY TX buffer */
- unsigned char txbuf[32];
+ unsigned char *txbuf;
unsigned char *txhead; /* Pointer to next TX byte */
int txleft; /* Bytes left to TX */
/* TTY RX helpers */
- unsigned char rxbuf[256];
+ unsigned char rxbuf[ELM327_SIZE_RXBUF];
int rxfill;
/* State machine */
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.
*/
static DEFINE_SPINLOCK(elmcan_discdata_lock);
-
static inline void elm327_hw_failure(struct elmcan *elm);
-
-
- /************************************************************************
- * ELM327: Transmission *
- * *
- * (all functions assume elm->lock taken) *
- ************************************************************************/
+ /***********************************************************************
+ * ELM327: Transmission *
+ * *
+ * (all functions assume elm->lock taken) *
+ ***********************************************************************/
static void elm327_send(struct elmcan *elm, const void *buf, size_t len)
{
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);
+ "Failed to write to tty %s.\n",
+ elm->tty->name);
elm327_hw_failure(elm);
return;
}
elm->txhead = elm->txbuf + actual;
}
-
-/*
- * Take the ELM327 out of almost any state and back into command mode
- *
- * Assumes elm->lock taken.
+/* Take the ELM327 out of almost any state and back into command mode.
+ * We send ELM327_MAGIC_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)
{
}
}
-
-/*
- * Schedule a CAN frame, and any necessary config changes,
- * to be sent down the TTY.
- *
- * Assumes elm->lock taken.
- */
+/* 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)
{
/* Schedule any necessary changes in ELM327's CAN configuration */
| ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
| elm->can_bitrate_divisor;
- set_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo);
+ set_bit(TODO_CAN_CONFIG, &elm->cmds_todo);
}
if (frame->can_id & CAN_EFF_FLAG) {
- clear_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo);
- set_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo);
- set_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ 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);
} else {
- set_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo);
- clear_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo);
- clear_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ 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);
}
}
/* Schedule the CAN frame itself. */
elm->can_frame = *frame;
- set_bit(ELM_TODO_CAN_DATA, &elm->cmds_todo);
+ set_bit(TODO_CAN_DATA, &elm->cmds_todo);
elm327_kick_into_cmd_mode(elm);
}
-
-
- /************************************************************************
- * ELM327: Initialization sequence *
- * *
- * (assumes elm->lock taken) *
- ************************************************************************/
+ /***********************************************************************
+ * ELM327: Initialization sequence *
+ * *
+ * (assumes elm->lock taken) *
+ ***********************************************************************/
static char *elm327_init_script[] = {
"AT WS\r", /* v1.0: Warm Start */
NULL
};
-
static void elm327_init(struct elmcan *elm)
{
elm->state = ELM_NOTINIT;
/* Configure ELM327 and then start monitoring */
elm->next_init_cmd = &elm327_init_script[0];
- set_bit(ELM_TODO_INIT, &elm->cmds_todo);
- set_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo);
- set_bit(ELM_TODO_RESPONSES, &elm->cmds_todo);
- set_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo);
+ 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);
elm327_kick_into_cmd_mode(elm);
}
-
-
- /************************************************************************
- * ELM327: Reception -> netdev glue *
- * *
- * (assumes elm->lock taken) *
- ************************************************************************/
+ /***********************************************************************
+ * ELM327: Reception -> netdev glue *
+ * *
+ * (assumes elm->lock taken) *
+ ***********************************************************************/
static void elm327_feed_frame_to_netdev(struct elmcan *elm,
const struct can_frame *frame)
memcpy(cf, frame, sizeof(struct can_frame));
- elm->dev->stats.rx_packets++;
- elm->dev->stats.rx_bytes += frame->can_dlc;
- netif_rx_ni(skb);
+ /* 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++;
- can_led_event(elm->dev, CAN_LED_EVENT_RX);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,15,0)
+ /* Wake NAPI */
+ can_rx_offload_irq_finish(&elm->offload);
+#endif
}
-
-
- /************************************************************************
- * ELM327: "Panic" handler *
- * *
- * (assumes elm->lock taken) *
- ************************************************************************/
+ /***********************************************************************
+ * 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)
can_bus_off(elm->dev);
}
-
-
- /************************************************************************
- * ELM327: Reception parser *
- * *
- * (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;
-}
-
+ /***********************************************************************
+ * ELM327: Reception parser *
+ * *
+ * (assumes elm->lock taken) *
+ ***********************************************************************/
static void elm327_parse_error(struct elmcan *elm, int 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");
+ "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.
+ * 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 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]);
+ 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;
elm327_feed_frame_to_netdev(elm, &frame);
}
-
+/* 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, int len)
{
struct can_frame frame;
* - 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] != ' ') {
+ if (hex_to_bin(elm->rxbuf[hexlen]) < 0 &&
+ elm->rxbuf[hexlen] != ' ') {
break;
}
}
* 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]) {
+ 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;
+ 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] == ' ') {
+ 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] == ' ') {
/* This is not a well-formatted data line.
* Assume it's an error message.
*/
- return 1;
+ 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 1;
+ return -ENODATA;
}
/* From here on all chars up to buf[hexlen] are hex or spaces,
}
/* Check for RTR frame */
- if (elm->rxfill >= hexlen + 3
- && elm->rxbuf[hexlen + 0] == 'R'
- && elm->rxbuf[hexlen + 1] == 'T'
- && elm->rxbuf[hexlen + 2] == 'R') {
+ 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? */
- if (!(frame.can_id & CAN_RTR_FLAG)
- && (hexlen < frame.can_dlc * 3 + datastart)) {
+ /* 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.
* However, this will correctly drop the state machine back into
* command mode.
*/
- return 2;
+ return -ENODATA;
}
/* 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);
+ 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. */
return 0;
}
-
static void elm327_parse_line(struct elmcan *elm, int len)
{
/* Skip empty lines */
}
}
-
static void elm327_handle_prompt(struct elmcan *elm)
{
struct can_frame *frame = &elm->can_frame;
}
/* 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));
+ if (test_bit(TODO_INIT, &elm->cmds_todo)) {
+ strcpy(local_txbuf, *elm->next_init_cmd);
+
elm->next_init_cmd++;
if (!(*elm->next_init_cmd)) {
- clear_bit(ELM_TODO_INIT, &elm->cmds_todo);
+ clear_bit(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);
-
- return;
-
- } else if (test_and_clear_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(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)) {
+ } else if (test_and_clear_bit(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)) {
+ } else if (test_and_clear_bit(TODO_CAN_CONFIG, &elm->cmds_todo)) {
sprintf(local_txbuf, "ATPC\r");
- set_bit(ELM_TODO_CAN_CONFIG_PART2, &elm->cmds_todo);
+ set_bit(TODO_CAN_CONFIG_PART2, &elm->cmds_todo);
- } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG_PART2, &elm->cmds_todo)) {
+ } else if (test_and_clear_bit(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)) {
+ } else if (test_and_clear_bit(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)) {
+ } else if (test_and_clear_bit(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)) {
+ } else if (test_and_clear_bit(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)) {
+ } else if (test_and_clear_bit(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.
int i;
for (i = 0; i < frame->can_dlc; i++) {
- sprintf(&local_txbuf[2*i], "%02X",
+ sprintf(&local_txbuf[2 * i], "%02X",
frame->data[i]);
}
- sprintf(&local_txbuf[2*i], "\r");
+ sprintf(&local_txbuf[2 * i], "\r");
}
elm->drop_next_line = 1;
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, int i)
{
- memmove(&elm->rxbuf[0], &elm->rxbuf[i], sizeof(elm->rxbuf) - i);
+ memmove(&elm->rxbuf[0], &elm->rxbuf[i], ELM327_SIZE_RXBUF - i);
elm->rxfill -= i;
}
-
static void elm327_parse_rxbuf(struct elmcan *elm)
{
int len;
switch (elm->state) {
case ELM_NOTINIT:
elm->rxfill = 0;
- return;
+ break;
case ELM_GETMAGICCHAR:
{
elm327_drop_bytes(elm, i);
- return;
+ break;
}
case ELM_GETPROMPT:
elm327_handle_prompt(elm);
elm->rxfill = 0;
- return;
+ break;
case ELM_RECEIVING:
/* Find <CR> delimiting feedback lines. */
/* empty loop */
}
- if (len == sizeof(elm->rxbuf)) {
+ 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");
+ "RX buffer overflow. Faulty ELM327 or UART?\n");
elm327_hw_failure(elm);
- return;
+ 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,
elm->rxfill = 0;
elm327_handle_prompt(elm);
- return;
+ break;
}
/* No <CR> found - we haven't received a full line yet.
* Wait for more data.
*/
- return;
+ 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);
+ elm327_drop_bytes(elm, len + 1);
/* More data to parse? */
if (elm->rxfill)
}
}
+ /***********************************************************************
+ * netdev *
+ * *
+ * (takes elm->lock) *
+ ***********************************************************************/
+/* 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);
+}
-
- /************************************************************************
- * netdev *
- * *
- * (takes elm->lock) *
- ************************************************************************/
-
-/* Netdevice DOWN -> UP routine */
static int elmcan_netdev_open(struct net_device *dev)
{
struct elmcan *elm = netdev_priv(dev);
return -EIO;
}
- if (elm->tty == NULL) {
+ if (!elm->tty) {
spin_unlock_bh(&elm->lock);
return -ENODEV;
}
return err;
}
- /* Initialize the ELM327 */
elm327_init(elm);
spin_unlock_bh(&elm->lock);
+ elm->offload.mailbox_read = elmcan_mailbox_read;
+ err = can_rx_offload_add_fifo(dev, &elm->offload, ELM327_NAPI_WEIGHT);
+ 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;
}
-/* Netdevice UP -> DOWN routine */
static int elmcan_netdev_close(struct net_device *dev)
{
struct elmcan *elm = netdev_priv(dev);
+ netif_stop_queue(dev);
+
spin_lock_bh(&elm->lock);
if (elm->tty) {
- /* TTY discipline is running. */
-
/* Interrupt whatever we're doing right now */
elm327_send(elm, ELM327_MAGIC_STRING, 1);
spin_unlock_bh(&elm->lock);
}
+ can_rx_offload_disable(&elm->offload);
elm->can.state = CAN_STATE_STOPPED;
- netif_stop_queue(dev);
+ 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 queue. */
+/* 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;
+ struct can_frame *frame = (struct can_frame *)skb->data;
if (skb->len != sizeof(struct can_frame))
goto out;
/* We shouldn't get here after a hardware fault:
* can_bus_off() calls netif_carrier_off()
*/
- BUG_ON(elm->hw_failure);
+ WARN_ON_ONCE(elm->hw_failure);
- if (elm->tty == NULL
- || elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
+ if (!elm->tty ||
+ elm->hw_failure ||
+ elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
spin_unlock(&elm->lock);
goto out;
}
return NETDEV_TX_OK;
}
-static int elmcan_netdev_change_mtu(struct net_device *dev, int new_mtu)
-{
- return -EINVAL;
-}
-
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 = elmcan_netdev_change_mtu,
+ .ndo_change_mtu = can_change_mtu,
};
+ /***********************************************************************
+ * Line discipline *
+ * *
+ * (takes elm->lock) *
+ ***********************************************************************/
-
-
-
- /************************************************************************
- * Line discipline *
- * *
- * (takes elm->lock) *
- ************************************************************************/
-
-/*
- * Get a reference to our struct, taking into account locks/refcounts.
+/* 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 (because tty->disc_data may be NULL).
+ * 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;
- /* Lock all elmcan TTYs, so tty->disc_data can't become NULL
- * the moment before we increase the reference counter.
- */
spin_lock_bh(&elmcan_discdata_lock);
- elm = (struct elmcan *) tty->disc_data;
+ elm = (struct elmcan *)tty->disc_data;
if (!elm) {
spin_unlock_bh(&elmcan_discdata_lock);
atomic_dec(&elm->refcount);
}
+static bool elmcan_is_valid_rx_char(char c)
+{
+ return (accept_flaky_uart ||
+ isdigit(c) ||
+ isupper(c) ||
+ c == ELM327_MAGIC_CHAR ||
+ c == ELM327_READY_CHAR ||
+ c == '<' ||
+ c == 'a' ||
+ c == 'b' ||
+ c == 'v' ||
+ c == '.' ||
+ c == '?' ||
+ c == '\r' ||
+ c == ' ');
+}
-
-/*
- * Handle the 'receiver data ready' interrupt.
- * This function is called by the 'tty_io' module in the kernel when
- * a block of ELM327 CAN data has been received, which can now be parsed
- * and sent on to some IP layer for further processing. This will not
- * be re-entered while running but other ldisc functions may be called
- * in parallel
+/* Handle incoming ELM327 ASCII data.
+ * This will not be re-entered while running, but other ldisc
+ * functions may be called in parallel.
*/
static void elmcan_ldisc_rx(struct tty_struct *tty,
- const unsigned char *cp, char *fp, int count)
+ const unsigned char *cp, char *fp, int count)
{
struct elmcan *elm = get_elm(tty);
return;
spin_lock_bh(&elm->lock);
- if (elm->hw_failure) {
- spin_unlock_bh(&elm->lock);
- put_elm(elm);
- return;
- }
+ if (elm->hw_failure)
+ goto out;
- /* Read the characters out of the buffer */
- while (count-- && elm->rxfill < sizeof(elm->rxbuf)) {
+ while (count-- && elm->rxfill < ELM327_SIZE_RXBUF) {
if (fp && *fp++) {
netdev_err(elm->dev, "Error in received character stream. Check your wiring.");
elm327_hw_failure(elm);
- spin_unlock_bh(&elm->lock);
- put_elm(elm);
- return;
+ goto out;
}
/* Ignore NUL characters, which the PIC microcontroller may
*/
if (*cp != 0) {
/* Check for stray characters on the UART line.
- * No idea what causes this.
+ * Likely caused by bad hardware.
*/
- 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.
- */
+ if (!elmcan_is_valid_rx_char(*cp)) {
netdev_err(elm->dev,
"Received illegal character %02x.\n",
*cp);
elm327_hw_failure(elm);
- spin_unlock_bh(&elm->lock);
- put_elm(elm);
- return;
+ goto out;
}
elm->rxbuf[elm->rxfill++] = *cp;
netdev_err(elm->dev, "Receive buffer overflowed. Bad chip or wiring?");
elm327_hw_failure(elm);
- spin_unlock_bh(&elm->lock);
- put_elm(elm);
- return;
+ goto out;
}
elm327_parse_rxbuf(elm);
- spin_unlock_bh(&elm->lock);
+out:
+ spin_unlock_bh(&elm->lock);
put_elm(elm);
}
-/*
- * Write out remaining transmit buffer.
+/* Write out remaining transmit buffer.
* Scheduled when TTY is writable.
*/
static void elmcan_ldisc_tx_worker(struct work_struct *work)
{
/* No need to use get_elm() here, as we'll always flush workers
- * befory destroying the elmcan object.
+ * before destroying the elmcan object.
*/
struct elmcan *elm = container_of(work, struct elmcan, tx_work);
ssize_t actual;
if (elm->txleft <= 0) {
/* Our TTY write buffer is empty:
- * We can start transmission of another packet
+ * Allow netdev to hand us another packet
*/
clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
spin_unlock_bh(&elm->lock);
spin_unlock_bh(&elm->lock);
}
-
-/*
- * Called by the driver when there's room for more data.
- * Schedule the transmit.
- */
+/* 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);
put_elm(elm);
}
-
-
/* 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.
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.
- */
+/* Dummy needed to use bitrate_const */
static int elmcan_do_set_bittiming(struct net_device *netdev)
{
+ (void)netdev;
+
return 0;
}
-
-/*
- * Open the high-level part of the elmcan channel.
- * This function is called by the TTY module when the
- * elmcan line discipline is called for.
- *
- * Called in process context serialized from other ldisc calls.
- */
static int elmcan_ldisc_open(struct tty_struct *tty)
{
struct net_device *dev;
if (!tty->ops->write)
return -EOPNOTSUPP;
-
- /* OK. Find a free elmcan channel to use. */
dev = alloc_candev(sizeof(struct elmcan), 0);
if (!dev)
return -ENFILE;
elm = netdev_priv(dev);
+ elm->txbuf = kmalloc(ELM327_SIZE_TXBUF, GFP_KERNEL);
+ if (!elm->txbuf) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+
/* Configure TTY interface */
tty->receive_room = 65536; /* We don't flow control */
elm->txleft = 0; /* Clear TTY TX buffer */
/* Let 'er rip */
err = register_candev(elm->dev);
- if (err) {
- free_candev(elm->dev);
- return err;
- }
+ if (err)
+ goto out_err;
netdev_info(elm->dev, "elmcan on %s.\n", tty->name);
return 0;
+
+out_err:
+ kfree(elm->txbuf);
+ free_candev(elm->dev);
+ return err;
}
-/*
- * Close down an elmcan channel.
+/* 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.
*/
static void elmcan_ldisc_close(struct tty_struct *tty)
{
- /* Use get_elm() to synchronize against other users */
struct elmcan *elm = get_elm(tty);
if (!elm)
return;
- /* Tear down network side.
- * unregister_netdev() calls .ndo_stop() so we don't have to.
- */
+ /* 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(),
put_elm(elm);
put_elm(elm);
- /* Spin until refcount reaches 0 */
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.
- */
+ /* At this point, all ldisc calls to us have become no-ops. */
+
+ flush_work(&elm->tx_work);
/* Mark channel as dead */
spin_lock_bh(&elm->lock);
elm->tty = NULL;
spin_unlock_bh(&elm->lock);
- /* Flush TTY side */
- flush_work(&elm->tx_work);
-
netdev_info(elm->dev, "elmcan off %s.\n", tty->name);
- /* Free our memory */
+ kfree(elm->txbuf);
free_candev(elm->dev);
}
return 0;
}
-/* Perform I/O control on an active elmcan channel. */
static int elmcan_ldisc_ioctl(struct tty_struct *tty, struct file *file,
- unsigned int cmd, unsigned long arg)
+ unsigned int cmd, unsigned long arg)
{
struct elmcan *elm = get_elm(tty);
unsigned int tmp;
switch (cmd) {
case SIOCGIFNAME:
- tmp = strlen(elm->dev->name) + 1;
+ tmp = strnlen(elm->dev->name, IFNAMSIZ - 1) + 1;
if (copy_to_user((void __user *)arg, elm->dev->name, tmp)) {
put_elm(elm);
return -EFAULT;
static struct tty_ldisc_ops elmcan_ldisc = {
.owner = THIS_MODULE,
- .magic = TTY_LDISC_MAGIC,
.name = "elmcan",
.receive_buf = elmcan_ldisc_rx,
.write_wakeup = elmcan_ldisc_tx_wakeup,
.ioctl = elmcan_ldisc_ioctl,
};
-
-
-
-
- /************************************************************************
- * Module init/exit *
- ************************************************************************/
-
static int __init elmcan_init(void)
{
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");
- /* Fill in our line protocol discipline, and register it */
status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc);
if (status)
- pr_err("can't register line discipline\n");
+ pr_err("Can't register line discipline\n");
return status;
}
projects / elmcan.git / blobdiff