diff options
Diffstat (limited to 'module')
| -rw-r--r-- | module/Makefile | 7 | ||||
| -rwxr-xr-x | module/attach-me.sh | 3 | ||||
| -rw-r--r-- | module/elmcan.c | 1062 |
3 files changed, 1072 insertions, 0 deletions
diff --git a/module/Makefile b/module/Makefile new file mode 100644 index 0000000..120df6b --- /dev/null +++ b/module/Makefile @@ -0,0 +1,7 @@ +obj-m += elmcan.o + +all: + make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules + +clean: + make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean diff --git a/module/attach-me.sh b/module/attach-me.sh new file mode 100755 index 0000000..d0c130c --- /dev/null +++ b/module/attach-me.sh @@ -0,0 +1,3 @@ +#!/bin/bash + +sudo ldattach --debug --speed 38400 --eightbits --noparity --onestopbit --iflag -ICRNL,INLCR,-IXOFF 26 $@ diff --git a/module/elmcan.c b/module/elmcan.c new file mode 100644 index 0000000..1e72461 --- /dev/null +++ b/module/elmcan.c @@ -0,0 +1,1062 @@ +/* + * 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> + * 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/init.h> +#include <linux/module.h> +#include <linux/moduleparam.h> + +#include <linux/bitops.h> +#include <linux/errno.h> +#include <linux/if_ether.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/spinlock.h> +#include <linux/string.h> +#include <linux/tty.h> +#include <linux/workqueue.h> + +#include <linux/can.h> +#include <linux/can/dev.h> +#include <linux/can/error.h> +#include <linux/can/led.h> + + +MODULE_ALIAS_LDISC(N_ELMCAN); +MODULE_DESCRIPTION("ELM327 based CAN interface"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Max Staudt <max-linux@enpas.org>"); + +/* Line discipline ID number */ +#ifndef N_ELMCAN +#define N_ELMCAN 26 +#endif + +#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_CAN_CONFIG_BAUDRATE_MULT_8_7 0x1000 + +#define ELM327_MAGIC_CHAR 'y' +#define ELM327_MAGIC_STRING "y" + + +/* 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, + ELM_TODO_RESPONSES, + ELM_TODO_SILENT_MONITOR, + ELM_TODO_INIT +}; + + +struct elmcan { + /* This must be the first member when using alloc_candev() */ + struct can_priv can; + + /* TTY and netdev devices that we're bridging */ + struct tty_struct *tty; + struct net_device *dev; + + int magic; + + /* Per-channel lock */ + spinlock_t lock; + + /* TTY TX helpers */ + struct work_struct tx_work; /* Flushes TTY TX buffer */ + unsigned char txbuf[32]; + unsigned char *txhead; /* Pointer to next TX byte */ + int txleft; /* Bytes left to TX */ + + /* TTY RX helpers */ + unsigned char rxbuf[256]; + int rxfill; + + /* State machine */ + enum { + ELM_NOTINIT = 0, + ELM_GETMAGICCHAR, + ELM_GETPROMPT, + ELM_RECEIVING, + } state; + + int 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; + + /* Things we have yet to send */ + char **next_init_cmd; + unsigned long cmds_todo; +}; + + +static DEFINE_SPINLOCK(elmcan_open_lock); + + + + + /************************************************************************ + * ELM327: Transmission * + ************************************************************************/ + +static void elm327_send(struct elmcan *elm, const void *buf, size_t len) +{ + int actual; + + 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); + elm->txleft = len - actual; + elm->txhead = elm->txbuf + actual; +} + + +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); + + elm->state = ELM_GETMAGICCHAR; + elm->rxfill = 0; + } +} + + +static void elm327_send_frame(struct elmcan *elm, struct can_frame *frame) +{ + 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) + | ELM327_CAN_CONFIG_VARIABLE_DLC + | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF + | elm->can_bitrate_divisor; + + set_bit(ELM_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); + } 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); + } + } + + elm->can_frame = *frame; + set_bit(ELM_TODO_CAN_DATA, &elm->cmds_todo); + + elm327_kick_into_cmd_mode(elm); +} + + + + /************************************************************************ + * ELM327: Initialization 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 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 */ + "AT CM 000\r", /* v1.0: Reset CAN ID Mask */ + "AT E1\r", /* v1.0: Echo On */ + "AT H1\r", /* v1.0: Headers On */ + "AT L0\r", /* v1.0: Linefeeds Off */ + "AT SH 7DF\r", /* v1.0: Set CAN sending ID to 0x7df */ + "AT ST FF\r", /* v1.0: Set maximum Timeout for response after TX */ + "AT AT0\r", /* v1.2: Adaptive Timing Off */ + "AT D1\r", /* v1.3: Print DLC On */ + "AT S1\r", /* v1.3: Spaces On */ + "AT TP B\r", /* v1.0: Try Protocol B */ + NULL +}; + + +static void elm327_init(struct elmcan *elm) +{ + elm->state = ELM_NOTINIT; + elm->can_frame.can_id = 0x7df; + elm->rxfill = 0; + elm->drop_next_line = 0; + + /* We can only set the bitrate as a fraction of 500000. + * The bit timing constants in elmcan_bittiming_const will + * limit the user to the right values. + */ + elm->can_bitrate_divisor = 500000 / elm->can.bittiming.bitrate; + elm->can_config = ELM327_CAN_CONFIG_SEND_SFF + | ELM327_CAN_CONFIG_VARIABLE_DLC + | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF + | elm->can_bitrate_divisor; + + /* 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); + + elm327_kick_into_cmd_mode(elm); +} + + + + /************************************************************************ + * ELM327: Reception -> netdev glue * + ************************************************************************/ + +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)) { + return; + } + + skb = alloc_can_skb(elm->dev, &cf); + + if (!skb) + return; + + memcpy(cf, frame, sizeof(struct can_frame)); + + elm->dev->stats.rx_packets++; + elm->dev->stats.rx_bytes += frame->can_dlc; + netif_rx_ni(skb); + + can_led_event(elm->dev, CAN_LED_EVENT_RX); +} + + + + /************************************************************************ + * ELM327: Panic handler * + ************************************************************************/ + +static inline void elm327_panic(struct elmcan *elm) +{ + struct can_frame frame = {0}; + + frame.can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED; + frame.can_dlc = CAN_ERR_DLC; + elm327_feed_frame_to_netdev(elm, &frame); + + pr_err("ELM327 misbehaved. Re-initializing.\n"); + + elm->can.can_stats.restarts++; + elm327_init(elm); +} + + + + /************************************************************************ + * ELM327: Reception parser * + ************************************************************************/ + +static void elm327_parse_error(struct elmcan *elm, int len) +{ + struct can_frame frame = {0}; + + 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; + } + + elm327_feed_frame_to_netdev(elm, &frame); +} + + +static int elm327_parse_frame(struct elmcan *elm, int len) +{ + struct can_frame frame = {0}; + int hexlen; + int datastart; + int i; + + /* 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. + * - 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] != ' ') { + break; + } + } + + /* 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] == ' ') { + 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. + * 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. */ + return 1; + } + + /* From here on all chars up to buf[hexlen] are hex or spaces, + * at well-defined offsets. */ + + /* Read CAN data length */ + frame.can_dlc = (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); + } 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); + } + + /* Check for RTR frame */ + if (elm->rxfill >= hexlen + 3 + && elm->rxbuf[hexlen + 0] == 'R' + && elm->rxbuf[hexlen + 1] == 'T' + && elm->rxbuf[hexlen + 2] == 'R') { + 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)) { + /* 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); + + /* Signal failure to parse. + * The line will be re-parsed as an error line, which will fail. + * However, this will correctly drop the state machine back into + * command mode. + */ + return 2; + } + + /* 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); + } + + /* Feed the frame to the network layer. */ + elm327_feed_frame_to_netdev(elm, &frame); + + return 0; +} + + +static void elm327_parse_line(struct elmcan *elm, int len) +{ + /* Skip empty lines */ + if (!len) { + return; + } + + /* Skip echo lines */ + if (elm->drop_next_line) { + elm->drop_next_line = 0; + return; + } else if (elm->rxbuf[0] == 'A' && elm->rxbuf[1] == 'T') { + return; + } + + /* Regular parsing */ + 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; + } +} + + +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); + } + + /* 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); + } 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"); + } + + elm->drop_next_line = 1; + elm->state = ELM_RECEIVING; + } + + elm327_send(elm, txbuf, strlen(txbuf)); + } else { + /* Enter CAN monitor mode */ + elm327_send(elm, "ATMA\r", 5); + elm->state = ELM_RECEIVING; + } +} + + +static void elm327_drop_bytes(struct elmcan *elm, int i) +{ + memmove(&elm->rxbuf[0], &elm->rxbuf[i], sizeof(elm->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; + + case ELM_GETMAGICCHAR: + { + /* Wait for 'y' or '>' */ + int i; + + for (i = 0; i < elm->rxfill; i++) { + if (elm->rxbuf[i] == ELM327_MAGIC_CHAR) { + elm327_send(elm, "\r", 1); + elm->state = ELM_GETPROMPT; + i++; + break; + } else if (elm->rxbuf[i] == '>') { + elm327_send(elm, ELM327_MAGIC_STRING, 1); + i++; + break; + } + } + + elm327_drop_bytes(elm, i); + + return; + } + + case ELM_GETPROMPT: + /* Wait for '>' */ + if (elm->rxbuf[elm->rxfill - 1] == '>') { + elm327_handle_prompt(elm); + } + + elm->rxfill = 0; + return; + + case ELM_RECEIVING: + /* Find <CR> delimiting feedback lines. */ + for (len = 0; + (len < elm->rxfill) && (elm->rxbuf[len] != '\r'); + len++) { + /* empty loop */ + } + + if (len == sizeof(elm->rxbuf)) { + /* 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); + } else if (len == elm->rxfill) { + if (elm->state == ELM_RECEIVING + && 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. */ + elm->rxfill = 0; + + elm327_handle_prompt(elm); + return; + } else { + /* We haven't received a full line yet. Wait for more data. */ + return; + } + } + + /* We have a full line to parse. */ + elm327_parse_line(elm, len); + + /* Remove parsed data from RX buffer. */ + elm327_drop_bytes(elm, len+1); + + /* More data to parse? */ + if (elm->rxfill) { + elm327_parse_rxbuf(elm); + } + } +} + + + + + + /************************************************************************ + * netdev * + ************************************************************************/ + +/* Netdevice DOWN -> UP routine */ +static int elmcan_netdev_open(struct net_device *dev) +{ + struct elmcan *elm = netdev_priv(dev); + int err; + + spin_lock_bh(&elm->lock); + if (elm->tty == NULL) { + spin_unlock_bh(&elm->lock); + return -ENODEV; + } + + /* open_candev() checks for elm->can.bittiming.bitrate != 0 */ + err = open_candev(dev); + if (err) { + spin_unlock_bh(&elm->lock); + return err; + } + + /* Initialize the ELM327 */ + elm327_init(elm); + spin_unlock_bh(&elm->lock); + + 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); + + 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); + + /* 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); + + spin_unlock_bh(&elm->lock); + + flush_work(&elm->tx_work); + } else { + spin_unlock_bh(&elm->lock); + } + + elm->can.state = CAN_STATE_STOPPED; + netif_stop_queue(dev); + close_candev(dev); + can_led_event(dev, CAN_LED_EVENT_STOP); + + return 0; +} + +/* Send a can_frame to a TTY queue. */ +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; + + if (skb->len != sizeof(struct can_frame)) + goto out; + + if (!netif_running(dev)) { + pr_warn("%s: xmit: iface is down\n", dev->name); + goto out; + } + + /* BHs are already disabled, so no spin_lock_bh(). + * See Documentation/networking/netdevices.txt + */ + spin_lock(&elm->lock); + if (elm->tty == NULL + || elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) { + spin_unlock(&elm->lock); + goto out; + } + + netif_stop_queue(dev); + + elm327_send_frame(elm, frame); + spin_unlock(&elm->lock); + + dev->stats.tx_packets++; + dev->stats.tx_bytes += frame->can_dlc; + + can_led_event(dev, CAN_LED_EVENT_TX); + +out: + kfree_skb(skb); + 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, +}; + + + + + + /************************************************************************ + * Line discipline * + ************************************************************************/ + +/* + * 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 + */ +static void elmcan_ldisc_rx(struct tty_struct *tty, + const unsigned char *cp, char *fp, int count) +{ + struct elmcan *elm = (struct elmcan *) tty->disc_data; + + if (!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."); + + spin_lock_bh(&elm->lock); + elm327_panic(elm); + spin_unlock_bh(&elm->lock); + return; + } + if (*cp != 0) { + elm->rxbuf[elm->rxfill++] = *cp; + } + cp++; + } + + if (count >= 0) { + pr_err("Receive buffer overflowed. Bad chip or wiring?"); + + spin_lock_bh(&elm->lock); + elm327_panic(elm); + spin_unlock_bh(&elm->lock); + return; + } + + spin_lock_bh(&elm->lock); + elm327_parse_rxbuf(elm); + spin_unlock_bh(&elm->lock); +} + +/* Write out remaining transmit buffer. + * Scheduled when TTY is writable. + */ +static void elmcan_ldisc_tx_worker(struct work_struct *work) +{ + struct elmcan *elm = container_of(work, struct elmcan, tx_work); + ssize_t actual; + + spin_lock_bh(&elm->lock); + /* First make sure we're connected. */ + if (!elm->tty || !netif_running(elm->dev)) { + spin_unlock_bh(&elm->lock); + return; + } + + if (elm->txleft <= 0) { + /* Our TTY write buffer is empty: + * We can start transmission of another packet + */ + 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) { + pr_err("Failed to write to tty for %s.\n", elm->dev->name); + elm327_panic(elm); + } + + elm->txleft -= actual; + elm->txhead += actual; + spin_unlock_bh(&elm->lock); +} + + +/* + * Called by the driver when there's room for more data. + * Schedule the transmit. + */ +static void elmcan_ldisc_tx_wakeup(struct tty_struct *tty) +{ + struct elmcan *elm = tty->disc_data; + + schedule_work(&elm->tx_work); +} + + + +/* 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, +}; + +/* + * 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; + struct elmcan *elm; + int err; + + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + + if (!tty->ops->write) + return -EOPNOTSUPP; + + elm = tty->disc_data; + + /* First make sure we're not already connected. + * Also, protect against simlutaneous open calls. */ + spin_lock_bh(&elmcan_open_lock); + if (elm) { + spin_unlock_bh(&elmcan_open_lock); + return -EEXIST; + } + spin_unlock_bh(&elmcan_open_lock); + + /* OK. Find a free elmcan channel to use. */ + dev = alloc_candev(sizeof(struct elmcan), 0); + if (!dev) + return -ENFILE; + elm = netdev_priv(dev); + + /* 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); + + /* Configure CAN metadata */ + elm->can.state = CAN_STATE_STOPPED; + elm->can.clock.freq = 1000000; + elm->can.bittiming_const = &elmcan_bittiming_const; + elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY; + + /* Configure netlink interface */ + elm->dev = dev; + dev->netdev_ops = &elmcan_netdev_ops; + + /* Mark ldisc channel as alive */ + elm->tty = tty; + tty->disc_data = elm; + + devm_can_led_init(elm->dev); + + /* Let 'er rip */ + err = register_candev(elm->dev); + if (err) { + free_candev(elm->dev); + return err; + } + + return 0; +} + +/* + * Close down an elmcan channel. + * This means flushing out any pending queues, and then returning. This + * call is serialized against other ldisc functions. + * + * We also use this method for a hangup event. + */ +static void elmcan_ldisc_close(struct tty_struct *tty) +{ + struct elmcan *elm = (struct elmcan *) tty->disc_data; + + /* First make sure we're connected. */ + if (!elm) + return; + + /* Flush network side */ + unregister_candev(elm->dev); + + /* Mark channel as dead */ + spin_lock_bh(&elm->lock); + tty->disc_data = NULL; + elm->tty = NULL; + spin_unlock_bh(&elm->lock); + + /* Flush TTY side */ + flush_work(&elm->tx_work); + + /* Free our memory */ + free_candev(elm->dev); +} + +static int elmcan_ldisc_hangup(struct tty_struct *tty) +{ + elmcan_ldisc_close(tty); + 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) +{ + struct elmcan *elm = (struct elmcan *) tty->disc_data; + unsigned int tmp; + + /* First make sure we're connected. */ + if (!elm) + return -EINVAL; + + switch (cmd) { + case SIOCGIFNAME: + tmp = strlen(elm->dev->name) + 1; + if (copy_to_user((void __user *)arg, elm->dev->name, tmp)) + return -EFAULT; + return 0; + + case SIOCSIFHWADDR: + return -EINVAL; + + default: + return tty_mode_ioctl(tty, file, cmd, arg); + } +} + +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, + .open = elmcan_ldisc_open, + .close = elmcan_ldisc_close, + .hangup = elmcan_ldisc_hangup, + .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"); + } + return status; +} + +static void __exit elmcan_exit(void) +{ + /* This will only be called when all channels have been closed by + * userspace - tty_ldisc.c takes care of the module's refcount. + */ + int status; + + status = tty_unregister_ldisc(N_ELMCAN); + if (status) { + pr_err("Can't unregister line discipline (error: %d)\n", status); + } +} + +module_init(elmcan_init); +module_exit(elmcan_exit); |