/************************************************************************
- * ELM327: Transmission *
+ * ELM327: Transmission *
+ * *
+ * (all functions assume elm->lock taken) *
************************************************************************/
static void elm327_send(struct elmcan *elm, const void *buf, size_t len)
}
+/*
+ * Take the ELM327 out of almost any state and back into command mode
+ *
+ * Assumes elm->lock taken.
+ */
static void elm327_kick_into_cmd_mode(struct elmcan *elm)
{
if (elm->state != ELM_GETMAGICCHAR && elm->state != ELM_GETPROMPT) {
}
+/*
+ * Schedule a CAN frame, and any necessary config changes,
+ * to be sent down the TTY.
+ *
+ * Assumes elm->lock taken.
+ */
static void elm327_send_frame(struct elmcan *elm, struct can_frame *frame)
{
+ /* 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)) {
}
}
+ /* Schedule the CAN frame itself. */
elm->can_frame = *frame;
set_bit(ELM_TODO_CAN_DATA, &elm->cmds_todo);
/************************************************************************
- * ELM327: Initialization sequence *
+ * ELM327: Initialization sequence *
+ * *
+ * (assumes elm->lock taken) *
************************************************************************/
static char *elm327_init_script[] = {
/************************************************************************
- * ELM327: Reception -> netdev glue *
+ * ELM327: Reception -> netdev glue *
+ * *
+ * (assumes elm->lock taken) *
************************************************************************/
static void elm327_feed_frame_to_netdev(struct elmcan *elm, const struct can_frame *frame)
/************************************************************************
- * ELM327: Panic handler *
+ * ELM327: Panic handler *
+ * *
+ * (assumes elm->lock taken) *
************************************************************************/
static inline void elm327_panic(struct elmcan *elm)
/************************************************************************
- * ELM327: Reception parser *
+ * ELM327: Reception parser *
+ * *
+ * (assumes elm->lock taken) *
************************************************************************/
static void elm327_parse_error(struct elmcan *elm, int len)
/* 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. */
+ * 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] == ' ') {
datastart = 6;
} else {
/* This is not a well-formatted data line.
- * Assume it's an error message. */
+ * Assume it's an error message.
+ */
return 1;
}
if (hexlen < datastart) {
/* The line is too short to be a valid frame hex dump.
- * Something interrupted the hex dump or it is invalid. */
+ * Something interrupted the hex dump or it is invalid.
+ */
return 1;
}
/* From here on all chars up to buf[hexlen] are hex or spaces,
- * at well-defined offsets. */
+ * at well-defined offsets.
+ */
/* Read CAN data length */
frame.can_dlc = (hex_to_bin(elm->rxbuf[datastart - 2]) << 0);
/* Incomplete frame. */
/* Probably the ELM327's RS232 TX buffer was full.
- * Emit an error frame and exit. */
+ * 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;
/* 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. */
+ * So let's do a dummy get-cmd-prompt dance.
+ */
elm->state = ELM_NOTINIT;
elm327_kick_into_cmd_mode(elm);
} else if (test_and_clear_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo)) {
if (len == sizeof(elm->rxbuf)) {
/* Line exceeds buffer. It's probably all garbage.
- * Did we even connect at the right baud rate? */
+ * Did we even connect at the right baud rate?
+ */
pr_err("RX buffer overflow. Faulty ELM327 connected?\n");
elm327_panic(elm);
} else if (len == elm->rxfill) {
&& 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. */
+ * Clear RX buffer and restart listening.
+ */
elm->rxfill = 0;
elm327_handle_prompt(elm);
return;
} else {
- /* We haven't received a full line yet. Wait for more data. */
+ /* We haven't received a full line yet.
+ * Wait for more data.
+ */
return;
}
}
/************************************************************************
- * netdev *
+ * netdev *
+ * *
+ * (takes elm->lock) *
************************************************************************/
/* Netdevice DOWN -> UP routine */
/************************************************************************
- * Line discipline *
+ * Line discipline *
+ * *
+ * (takes elm->lock) *
************************************************************************/
/*
spin_unlock_bh(&elm->lock);
}
-/* 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)
/*
* Close down an elmcan channel.
- * This means flushing out any pending queues, and then returning. This
- * call is serialized against other ldisc functions.
+ * This means flushing out any pending queues, and then returning.
+ * This call is serialized against other ldisc functions:
+ * Once this is called, no other ldisc function of ours is entered.
*
- * We also use this method for a hangup event.
+ * We also use this function for a hangup event.
*/
static void elmcan_ldisc_close(struct tty_struct *tty)
{
/************************************************************************
- * Module init/exit *
+ * Module init/exit *
************************************************************************/
static int __init elmcan_init(void)
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