Updates for 5.14

The 5.14 kernel reworked the tty register and unregister call
arguments, and made one of the arguments to the receive_buf
callback const, add some kernel version conditionals to handle
those.

Upstream-Status: Inappropriate [no upstream]
Signed-off-by: Scott Murray <scott.murray@konsulko.com>

---
 sllin/sllin.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/sllin/sllin.c b/sllin/sllin.c
index 904cff9..b89d06d 100644
--- a/sllin/sllin.c
+++ b/sllin/sllin.c
@@ -72,6 +72,12 @@
 #include <linux/version.h>
 #include "linux/lin_bus.h"
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,14,0)
+#define FP_CONST const
+#else
+#define FP_CONST
+#endif
+
 /* Should be in include/linux/tty.h */
 #define N_SLLIN			25
 /* -------------------------------- */
@@ -185,9 +191,9 @@ struct sllin {
 static struct net_device **sllin_devs;
 static int sllin_configure_frame_cache(struct sllin *sl, struct can_frame *cf);
 static void sllin_slave_receive_buf(struct tty_struct *tty,
-			      const unsigned char *cp, char *fp, int count);
+			      const unsigned char *cp, FP_CONST char *fp, int count);
 static void sllin_master_receive_buf(struct tty_struct *tty,
-			      const unsigned char *cp, char *fp, int count);
+			      const unsigned char *cp, FP_CONST char *fp, int count);
 
 
 /* Values of two parity bits in LIN Protected
@@ -492,7 +498,7 @@ static void sll_setup(struct net_device *dev)
   Routines looking at TTY side.
  ******************************************/
 static void sllin_master_receive_buf(struct tty_struct *tty,
-			      const unsigned char *cp, char *fp, int count)
+			      const unsigned char *cp, FP_CONST char *fp, int count)
 {
 	struct sllin *sl = (struct sllin *) tty->disc_data;
 
@@ -735,7 +741,7 @@ static void sllin_slave_finish_rx_msg(struct sllin *sl)
 }
 
 static void sllin_slave_receive_buf(struct tty_struct *tty,
-			      const unsigned char *cp, char *fp, int count)
+			      const unsigned char *cp, FP_CONST char *fp, int count)
 {
 	struct sllin *sl = (struct sllin *) tty->disc_data;
 	int lin_id;
@@ -842,7 +848,7 @@ static void sllin_slave_receive_buf(struct tty_struct *tty,
 }
 
 static void sllin_receive_buf(struct tty_struct *tty,
-			      const unsigned char *cp, char *fp, int count)
+			      const unsigned char *cp, FP_CONST char *fp, int count)
 {
 	struct sllin *sl = (struct sllin *) tty->disc_data;
 	netdev_dbg(sl->dev, "sllin_receive_buf invoked, count = %u\n", count);
@@ -1619,6 +1625,9 @@ static int sllin_ioctl(struct tty_struct *tty, struct file *file,
 
 static struct tty_ldisc_ops sll_ldisc = {
 	.owner		= THIS_MODULE,
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,14,0)
+	.num		= N_SLLIN,
+#endif
 #if LINUX_VERSION_CODE < KERNEL_VERSION(5,13,0)
 	.magic		= TTY_LDISC_MAGIC,
 #endif
@@ -1648,7 +1657,11 @@ static int __init sllin_init(void)
 	}
 
 	/* Fill in our line protocol discipline, and register it */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,14,0)
+	status = tty_register_ldisc(&sll_ldisc);
+#else
 	status = tty_register_ldisc(N_SLLIN, &sll_ldisc);
+#endif
 	if (status)  {
 		pr_err("sllin: can't register line discipline\n");
 		kfree(sllin_devs);
@@ -1719,9 +1732,15 @@ static void __exit sllin_exit(void)
 	kfree(sllin_devs);
 	sllin_devs = NULL;
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5,14,0)
+	tty_unregister_ldisc(&sll_ldisc);
+
+#else
 	i = tty_unregister_ldisc(N_SLLIN);
+
 	if (i)
 		pr_err("sllin: can't unregister ldisc (err %d)\n", i);
+#endif
 }
 
 module_init(sllin_init);