Re: [PATCH] watchdog: mpc8xxx_wdt convert to watchdog core

Guenter Roeck
2013-12-01T19:38:05Z

On 11/30/2013 07:33 AM, Christophe Leroy wrote:
> Convert mpc8xxx_wdt.c to the new watchdog API.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>
> diff -ur a/drivers/watchdog/mpc8xxx_wdt.c b/drivers/watchdog/mpc8xxx_wdt.c
> --- a/drivers/watchdog/mpc8xxx_wdt.c 2013-05-11 22:57:46.000000000 +0200
> +++ b/drivers/watchdog/mpc8xxx_wdt.c 2013-11-30 16:14:53.803495472 +0100
> @@ -72,28 +72,31 @@
> * to 0
> */
> static int prescale = 1;
> -static unsigned int timeout_sec;
>
> -static unsigned long wdt_is_open;
> static DEFINE_SPINLOCK(wdt_spinlock);
>
> -static void mpc8xxx_wdt_keepalive(void)
> +static int mpc8xxx_wdt_ping(struct watchdog_device *w)
> {
> /* Ping the WDT */
> spin_lock(&wdt_spinlock);
> out_be16(&wd_base->swsrr, 0x556c);
> out_be16(&wd_base->swsrr, 0xaa39);
> spin_unlock(&wdt_spinlock);
> + return 0;

The return code is never checked, so you can make this function void.

> }
>
> +static struct watchdog_device mpc8xxx_wdt_dev;
> static void mpc8xxx_wdt_timer_ping(unsigned long arg);
> -static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0, 0);
> +static DEFINE_TIMER(wdt_timer, mpc8xxx_wdt_timer_ping, 0,
> + (unsigned long)&mpc8xxx_wdt_dev);
>
> static void mpc8xxx_wdt_timer_ping(unsigned long arg)
> {
> - mpc8xxx_wdt_keepalive();
> + struct watchdog_device *w = (struct watchdog_device *)arg;
> +
> + mpc8xxx_wdt_ping(w);
> /* We're pinging it twice faster than needed, just to be sure. */
> - mod_timer(&wdt_timer, jiffies + HZ * timeout_sec / 2);
> + mod_timer(&wdt_timer, jiffies + HZ * w->timeout / 2);
> }
>
> static void mpc8xxx_wdt_pr_warn(const char *msg)
> @@ -102,19 +105,9 @@
> reset ? "reset" : "machine check exception");
> }
>
> -static ssize_t mpc8xxx_wdt_write(struct file *file, const char __user *buf,
> - size_t count, loff_t *ppos)
> -{
> - if (count)
> - mpc8xxx_wdt_keepalive();
> - return count;
> -}
> -
> -static int mpc8xxx_wdt_open(struct inode *inode, struct file *file)
> +static int mpc8xxx_wdt_start(struct watchdog_device *w)
> {
> u32 tmp = SWCRR_SWEN;
> - if (test_and_set_bit(0, &wdt_is_open))
> - return -EBUSY;
>
> /* Once we start the watchdog we can't stop it */
> if (nowayout)

This code and the subsequent module_get can be removed; it is handled by the infrastructure.

> @@ -132,59 +125,30 @@
>
> del_timer_sync(&wdt_timer);
>
> - return nonseekable_open(inode, file);
> + return 0;
> }
>
> -static int mpc8xxx_wdt_release(struct inode *inode, struct file *file)
> +static int mpc8xxx_wdt_stop(struct watchdog_device *w)
> {
> - if (!nowayout)
> - mpc8xxx_wdt_timer_ping(0);
> - else
> - mpc8xxx_wdt_pr_warn("watchdog closed");
> - clear_bit(0, &wdt_is_open);
> + mpc8xxx_wdt_timer_ping((unsigned long)w);

I really dislike this typecasting back and forth.

I think it would be better to move the mod_timer() call from mpc8xxx_wdt_timer_ping
into mpc8xxx_wdt_ping and call mpc8xxx_wdt_ping directly whenever possible.
From mpc8xxx_wdt_timer_ping you can then just call mpc8xxx_wdt_ping with the
typecasted parameter.

> return 0;
> }
>
> -static long mpc8xxx_wdt_ioctl(struct file *file, unsigned int cmd,
> - unsigned long arg)
> -{
> - void __user *argp = (void __user *)arg;
> - int __user *p = argp;
> - static const struct watchdog_info ident = {
> - .options = WDIOF_KEEPALIVEPING,
> - .firmware_version = 1,
> - .identity = "MPC8xxx",
> - };
> -
> - switch (cmd) {
> - case WDIOC_GETSUPPORT:
> - return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
> - case WDIOC_GETSTATUS:
> - case WDIOC_GETBOOTSTATUS:
> - return put_user(0, p);
> - case WDIOC_KEEPALIVE:
> - mpc8xxx_wdt_keepalive();
> - return 0;
> - case WDIOC_GETTIMEOUT:
> - return put_user(timeout_sec, p);
> - default:
> - return -ENOTTY;
> - }
> -}
> +static struct watchdog_info mpc8xxx_wdt_info = {
> + .options = WDIOF_KEEPALIVEPING,
> + .firmware_version = 1,
> + .identity = "MPC8xxx",
> +};
>
> -static const struct file_operations mpc8xxx_wdt_fops = {
> - .owner = THIS_MODULE,
> - .llseek = no_llseek,
> - .write = mpc8xxx_wdt_write,
> - .unlocked_ioctl = mpc8xxx_wdt_ioctl,
> - .open = mpc8xxx_wdt_open,
> - .release = mpc8xxx_wdt_release,
> +static struct watchdog_ops mpc8xxx_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = mpc8xxx_wdt_start,
> + .stop = mpc8xxx_wdt_stop,
> };
>
> -static struct miscdevice mpc8xxx_wdt_miscdev = {
> - .minor = WATCHDOG_MINOR,
> - .name = "watchdog",
> - .fops = &mpc8xxx_wdt_fops,
> +static struct watchdog_device mpc8xxx_wdt_dev = {
> + .info = &mpc8xxx_wdt_info,
> + .ops = &mpc8xxx_wdt_ops,
> };
>
> static const struct of_device_id mpc8xxx_wdt_match[];
> @@ -196,6 +160,7 @@
> const struct mpc8xxx_wdt_type *wdt_type;
> u32 freq = fsl_get_sys_freq();
> bool enabled;
> + unsigned int timeout_sec;
>
> match = of_match_device(mpc8xxx_wdt_match, &ofdev->dev);
> if (!match)
> @@ -222,6 +187,7 @@
> else
> timeout_sec = timeout / freq;
>
> + mpc8xxx_wdt_dev.timeout = timeout_sec;
> #ifdef MODULE
> ret = mpc8xxx_wdt_init_late();
> if (ret)
> @@ -237,7 +203,7 @@
> * userspace handles it.
> */
> if (enabled)
> - mpc8xxx_wdt_timer_ping(0);
> + mpc8xxx_wdt_timer_ping((unsigned long)&mpc8xxx_wdt_dev);
> return 0;
> err_unmap:
> iounmap(wd_base);
> @@ -249,7 +215,7 @@
> {
> mpc8xxx_wdt_pr_warn("watchdog removed");

The mpc8xxx_wdt_pr_warn function is now rather unnecessary since
it is called only once. Might as well merge it into this function.

> del_timer_sync(&wdt_timer);
> - misc_deregister(&mpc8xxx_wdt_miscdev);
> + watchdog_unregister_device(&mpc8xxx_wdt_dev);
> iounmap(wd_base);
>
> return 0;
> @@ -301,10 +267,11 @@
> if (!wd_base)
> return -ENODEV;
>
> - ret = misc_register(&mpc8xxx_wdt_miscdev);
> + watchdog_set_nowayout(&mpc8xxx_wdt_dev, nowayout);
> +
> + ret = watchdog_register_device(&mpc8xxx_wdt_dev);
> if (ret) {
> - pr_err("cannot register miscdev on minor=%d (err=%d)\n",
> - WATCHDOG_MINOR, ret);
> + pr_err("cannot register watchdog device (err=%d)\n", ret);
> return ret;
> }
> return 0;
> diff -ur a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1146,6 +1146,7 @@
> config 8xxx_WDT
> tristate "MPC8xxx Platform Watchdog Timer"
> depends on PPC_8xx || PPC_83xx || PPC_86xx
> + select WATCHDOG_CORE
> help
> This driver is for a SoC level watchdog that exists on some
> Freescale PowerPC processors. So far this driver supports:
>
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