Forward port to Linux v5.17-rc3

[elmcan.git] / module / elmcan.c

diff --git a/module/elmcan.c b/module/elmcan.c
index cd57cad9db3a86c24ed02b98b782a03579a40c69..acb605781c6d4387e50e0f4a6d7eece20afa47ae 100644 (file)
--- a/module/elmcan.c
+++ b/module/elmcan.c
@@ -2,13 +2,23 @@
 /* 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
@@ -30,9 +40,12 @@
 #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>
@@ -778,7 +791,7 @@ static struct sk_buff *elmcan_mailbox_read(struct can_rx_offload *offload,
                                           unsigned int n, u32 *timestamp,
                                           bool drop)
 {
-       WARN_ON(1); /* This function is a dummy, so don't call it! */
+       WARN_ON_ONCE(1); /* This function is a dummy, so don't call it! */
 
        return ERR_PTR(-ENOBUFS);
 }
@@ -881,7 +894,7 @@ static netdev_tx_t elmcan_netdev_start_xmit(struct sk_buff *skb,
        /* We shouldn't get here after a hardware fault:
         * can_bus_off() calls netif_carrier_off()
         */
-       WARN_ON(elm->hw_failure);
+       WARN_ON_ONCE(elm->hw_failure);
 
        if (!elm->tty ||
            elm->hw_failure ||
@@ -972,8 +985,13 @@ static bool elmcan_is_valid_rx_char(char c)
  * 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);
 
@@ -1221,13 +1239,22 @@ static void elmcan_ldisc_close(struct tty_struct *tty)
        free_candev(elm->dev);
 }
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,16,0)
 static int elmcan_ldisc_hangup(struct tty_struct *tty)
+#else
+static void elmcan_ldisc_hangup(struct tty_struct *tty)
+#endif
 {
        elmcan_ldisc_close(tty);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,16,0)
        return 0;
+#endif
 }
 
-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);
@@ -1253,13 +1280,18 @@ static int elmcan_ldisc_ioctl(struct tty_struct *tty, struct file *file,
 
        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_ELMCAN,
        .receive_buf    = elmcan_ldisc_rx,
        .write_wakeup   = elmcan_ldisc_tx_wakeup,
        .open           = elmcan_ldisc_open,
@@ -1272,10 +1304,14 @@ static int __init elmcan_init(void)
 {
        int status;
 
-       pr_info("ELM327 based best-effort CAN interface driver\n");
+       pr_info("ELM327 based best effort CAN interface driver\n");
        pr_info("This device is severely limited as a CAN interface, see documentation.\n");
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
        status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc);
+#else
+       status = tty_register_ldisc(&elmcan_ldisc);
+#endif
        if (status)
                pr_err("Can't register line discipline\n");
 
@@ -1287,12 +1323,16 @@ 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.
         */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0)
        int status;
 
        status = tty_unregister_ldisc(N_ELMCAN);
        if (status)
                pr_err("Can't unregister line discipline (error: %d)\n",
                       status);
+#else
+       tty_unregister_ldisc(&elmcan_ldisc);
+#endif
 }
 
 module_init(elmcan_init);