watchdog: f71808e_wdt: do stricter parameter validation

We check the f71862fg_pin module parameter every time a watchdog device
for the f71862fg is opened, but the parameter can't change at runtime.

If we move the check to the start of init:

  - We catch userspace passing invalid, but unused, values
  - We check the condition only once
  - We simplify the code

Do so.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200611191750.28096-6-a.fatoum@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

diff --git a/drivers/watchdog/f71808e_wdt.c b/drivers/watchdog/f71808e_wdt.c
index 26bf366aebc23a8e12b2007b1ace33e2a41f0a79..9f7823819ed1b5836b3b48603aeea34171bfd830 100644 (file)
--- a/drivers/watchdog/f71808e_wdt.c
+++ b/drivers/watchdog/f71808e_wdt.c
@@ -306,27 +306,6 @@ exit_unlock:
        return err;
 }
 
-static int f71862fg_pin_configure(unsigned short ioaddr)
-{
-       /* When ioaddr is non-zero the calling function has to take care of
-          mutex handling and superio preparation! */
-
-       if (f71862fg_pin == 63) {
-               if (ioaddr) {
-                       /* SPI must be disabled first to use this pin! */
-                       superio_clear_bit(ioaddr, SIO_REG_ROM_ADDR_SEL, 6);
-                       superio_set_bit(ioaddr, SIO_REG_MFUNCT3, 4);
-               }
-       } else if (f71862fg_pin == 56) {
-               if (ioaddr)
-                       superio_set_bit(ioaddr, SIO_REG_MFUNCT1, 1);
-       } else {
-               pr_err("Invalid argument f71862fg_pin=%d\n", f71862fg_pin);
-               return -EINVAL;
-       }
-       return 0;
-}
-
 static int watchdog_start(void)
 {
        int err;
@@ -352,9 +331,13 @@ static int watchdog_start(void)
                break;
 
        case f71862fg:
-               err = f71862fg_pin_configure(watchdog.sioaddr);
-               if (err)
-                       goto exit_superio;
+               if (f71862fg_pin == 63) {
+                       /* SPI must be disabled first to use this pin! */
+                       superio_clear_bit(watchdog.sioaddr, SIO_REG_ROM_ADDR_SEL, 6);
+                       superio_set_bit(watchdog.sioaddr, SIO_REG_MFUNCT3, 4);
+               } else if (f71862fg_pin == 56) {
+                       superio_set_bit(watchdog.sioaddr, SIO_REG_MFUNCT1, 1);
+               }
                break;
 
        case f71868:
@@ -810,7 +793,6 @@ static int __init f71808e_find(int sioaddr)
                break;
        case SIO_F71862_ID:
                watchdog.type = f71862fg;
-               err = f71862fg_pin_configure(0); /* validate module parameter */
                break;
        case SIO_F71868_ID:
                watchdog.type = f71868;
@@ -859,6 +841,11 @@ static int __init f71808e_init(void)
        int err = -ENODEV;
        int i;
 
+       if (f71862fg_pin != 63 && f71862fg_pin != 56) {
+               pr_err("Invalid argument f71862fg_pin=%d\n", f71862fg_pin);
+               return -EINVAL;
+       }
+
        for (i = 0; i < ARRAY_SIZE(addrs); i++) {
                err = f71808e_find(addrs[i]);
                if (err == 0)