#include <linux/can/rx-offload.h>
/* 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
+ * 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
#define ELM327_NAPI_WEIGHT 4
-#define ELM327_SIZE_RXBUF 256
+#define ELM327_SIZE_RXBUF 224
#define ELM327_SIZE_TXBUF 32
#define ELM327_CAN_CONFIG_SEND_SFF 0x8000
struct can_rx_offload offload;
+ /* TTY buffers */
+ u8 rxbuf[ELM327_SIZE_RXBUF];
+ u8 txbuf[ELM327_SIZE_TXBUF] ____cacheline_aligned;
+
+ /* TTY buffer accounting */
+ struct work_struct tx_work; /* Flushes TTY TX buffer */
+ u8 *txhead; /* Next TX byte */
+ unsigned txleft; /* Bytes left to TX */
+ int rxfill; /* Bytes already RX'd in buffer */
+
/* TTY and netdev devices that we're bridging */
struct tty_struct *tty;
struct net_device *dev;
/* Per-channel lock */
spinlock_t lock;
- /* 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;
-
- /* TTY TX helpers */
- 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 */
- u8 rxbuf[ELM327_SIZE_RXBUF];
- int rxfill;
-
/* State machine */
enum {
ELM327_STATE_NOTINIT = 0,
ELM327_STATE_RECEIVING,
} state;
- bool drop_next_line;
+ /* 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
u16 can_config;
u8 can_bitrate_divisor;
- /* Things we have yet to send */
- char **next_init_cmd;
- unsigned long cmds_todo;
+ /* 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);
elm->txleft = len - written;
elm->txhead = elm->txbuf + written;
- if (!elm->txleft)
- netif_wake_queue(elm->dev);
- else
+ if (elm->txleft)
set_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
}
elm327_send(elm, "ATMA\r", 5);
elm->state = ELM327_STATE_RECEIVING;
+ /* We will be in the default state once this command is
+ * send, so enable the TX packet queue.
+ */
+ netif_wake_queue(elm->dev);
+
return;
}
elm->drop_next_line = 1;
elm->state = ELM327_STATE_RECEIVING;
+
+ /* We will be in the default state once this command is
+ * send, so enable the TX packet queue.
+ */
+ netif_wake_queue(elm->dev);
}
elm327_send(elm, local_txbuf, strlen(local_txbuf));
int err;
spin_lock_bh(&elm->lock);
- if (elm->uart_side_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) {
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) {
{
struct elmcan *elm = netdev_priv(dev);
- netif_stop_queue(dev);
-
+ /* Interrupt whatever the ELM327 is doing right now */
spin_lock_bh(&elm->lock);
- if (elm->tty) {
- /* Interrupt whatever we're doing right now */
- 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
- */
- clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+ elm327_send(elm, ELM327_DUMMY_STRING, 1);
+ spin_unlock_bh(&elm->lock);
- spin_unlock_bh(&elm->lock);
+ netif_stop_queue(dev);
- flush_work(&elm->tx_work);
- } else {
- spin_unlock_bh(&elm->lock);
- }
+ /* 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;
if (!elm->txleft) {
clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
spin_unlock_bh(&elm->lock);
- netif_wake_queue(elm->dev);
} else {
spin_unlock_bh(&elm->lock);
}
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 */
spin_lock_init(&elm->lock);
INIT_WORK(&elm->tx_work, elmcan_ldisc_tx_worker);
return 0;
out_err:
- kfree(elm->txbuf);
free_candev(elm->dev);
return err;
}
{
struct elmcan *elm = (struct elmcan *)tty->disc_data;
- /* unregister_netdev() calls .ndo_stop() so we don't have to. */
+ /* 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);
- /* 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 */
spin_lock_bh(&elm->lock);
tty->disc_data = NULL;
netdev_info(elm->dev, "elmcan off %s.\n", tty->name);
- kfree(elm->txbuf);
free_candev(elm->dev);
}
projects / elmcan.git / blobdiff