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SubjectRe: [PATCH v4] watchdog: alim1535: Rewriting of alim1535 to use watchdog subsystem
Take a second look. It is different. And I had to amend the title hence 
the second send to include the subsystem, as you so duly tend to remind
me. It just so happened that I mistyped and skipped a version by...1.

Mark

On Thu, 1 Aug 2019, Guenter Roeck wrote:

> On 8/1/19 8:26 PM, Mark Balantzyan wrote:
>> This patch rewrites the alim1535_wdt driver to use the watchdog subsystem.
>> By virtue of this, it also fixes a (theoretical) race condition between the
>> formerly arranged ali_timeout_bits and ali_settimer() interoperation.
>>
>> Signed-off-by: Mark Balantzyan <mbalant3@gmail.com>
>
>
> This is v4. A minute ago I received v1. Earlier today I got v2, which I
> commented on. I didn't see v3 of this patch. I don't see a change log.
> At first glance, I don't see a difference to v2.
>
> Sorry, this is a waste of my time. I won't review or comment further.
>
> Guenter
>
>>
>> ---
>> drivers/watchdog/Kconfig | 1 +
>> drivers/watchdog/alim1535_wdt.c | 275 +++++---------------------------
>> 2 files changed, 37 insertions(+), 239 deletions(-)
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 9af07fd9..980b0c90 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -853,6 +853,7 @@ config ADVANTECH_WDT
>> config ALIM1535_WDT
>> tristate "ALi M1535 PMU Watchdog Timer"
>> + select WATCHDOG_CORE
>> depends on X86 && PCI
>> ---help---
>> This is the driver for the hardware watchdog on the ALi M1535 PMU.
>> diff --git a/drivers/watchdog/alim1535_wdt.c
>> b/drivers/watchdog/alim1535_wdt.c
>> index 60f0c2eb..55648ba8 100644
>> --- a/drivers/watchdog/alim1535_wdt.c
>> +++ b/drivers/watchdog/alim1535_wdt.c
>> @@ -12,26 +12,18 @@
>> #include <linux/module.h>
>> #include <linux/moduleparam.h>
>> #include <linux/types.h>
>> -#include <linux/miscdevice.h>
>> #include <linux/watchdog.h>
>> #include <linux/ioport.h>
>> -#include <linux/notifier.h>
>> -#include <linux/reboot.h>
>> -#include <linux/init.h>
>> -#include <linux/fs.h>
>> -#include <linux/pci.h>
>> #include <linux/uaccess.h>
>> #include <linux/io.h>
>> +#include <linux/pci.h>
>> #define WATCHDOG_NAME "ALi_M1535"
>> #define WATCHDOG_TIMEOUT 60 /* 60 sec default timeout */
>> /* internal variables */
>> -static unsigned long ali_is_open;
>> -static char ali_expect_release;
>> static struct pci_dev *ali_pci;
>> static u32 ali_timeout_bits; /* stores the computed
>> timeout */
>> -static DEFINE_SPINLOCK(ali_lock); /* Guards the hardware */
>> /* module parameters */
>> static int timeout = WATCHDOG_TIMEOUT;
>> @@ -53,18 +45,15 @@ MODULE_PARM_DESC(nowayout,
>> * configuration set.
>> */
>> -static void ali_start(void)
>> +static int ali_start(struct watchdog_device *wdd)
>> {
>> u32 val;
>> - spin_lock(&ali_lock);
>> -
>> pci_read_config_dword(ali_pci, 0xCC, &val);
>> val &= ~0x3F; /* Mask count */
>> val |= (1 << 25) | ali_timeout_bits;
>> pci_write_config_dword(ali_pci, 0xCC, val);
>> -
>> - spin_unlock(&ali_lock);
>> + return 0;
>> }
>> /*
>> @@ -73,18 +62,15 @@ static void ali_start(void)
>> * Stop the ALi watchdog countdown
>> */
>> -static void ali_stop(void)
>> +static int ali_stop(struct watchdog_device *wdd)
>> {
>> u32 val;
>> - spin_lock(&ali_lock);
>> -
>> pci_read_config_dword(ali_pci, 0xCC, &val);
>> val &= ~0x3F; /* Mask count to zero (disabled) */
>> val &= ~(1 << 25); /* and for safety mask the reset enable */
>> pci_write_config_dword(ali_pci, 0xCC, val);
>> -
>> - spin_unlock(&ali_lock);
>> + return 0;
>> }
>> /*
>> @@ -93,32 +79,24 @@ static void ali_stop(void)
>> * Send a keepalive to the timer (actually we restart the timer).
>> */
>> -static void ali_keepalive(void)
>> +static int ali_keepalive(struct watchdog_device *wdd)
>> {
>> - ali_start();
>> + ali_start(wdd);
>> + return 0;
>> }
>> /*
>> - * ali_settimer - compute the timer reload value
>> + * ali_set_timeout - compute the timer reload value
>> * @t: time in seconds
>> *
>> * Computes the timeout values needed
>> */
>> -static int ali_settimer(int t)
>> +static int ali_set_timeout(struct watchdog_device *wdd, unsigned int t)
>> {
>> - if (t < 0)
>> - return -EINVAL;
>> - else if (t < 60)
>> - ali_timeout_bits = t|(1 << 6);
>> - else if (t < 3600)
>> - ali_timeout_bits = (t / 60)|(1 << 7);
>> - else if (t < 18000)
>> - ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);
>> - else
>> - return -EINVAL;
>> -
>> - timeout = t;
>> + wdd->max_timeout = 60;
>> + wdd->min_timeout = 1;
>> + wdd->timeout = t;
>> return 0;
>> }
>> @@ -126,172 +104,6 @@ static int ali_settimer(int t)
>> * /dev/watchdog handling
>> */
>> -/*
>> - * ali_write - writes to ALi watchdog
>> - * @file: file from VFS
>> - * @data: user address of data
>> - * @len: length of data
>> - * @ppos: pointer to the file offset
>> - *
>> - * Handle a write to the ALi watchdog. Writing to the file pings
>> - * the watchdog and resets it. Writing the magic 'V' sequence allows
>> - * the next close to turn off the watchdog.
>> - */
>> -
>> -static ssize_t ali_write(struct file *file, const char __user *data,
>> - size_t len, loff_t *ppos)
>> -{
>> - /* See if we got the magic character 'V' and reload the timer */
>> - if (len) {
>> - if (!nowayout) {
>> - size_t i;
>> -
>> - /* note: just in case someone wrote the
>> - magic character five months ago... */
>> - ali_expect_release = 0;
>> -
>> - /* scan to see whether or not we got
>> - the magic character */
>> - for (i = 0; i != len; i++) {
>> - char c;
>> - if (get_user(c, data + i))
>> - return -EFAULT;
>> - if (c == 'V')
>> - ali_expect_release = 42;
>> - }
>> - }
>> -
>> - /* someone wrote to us, we should reload the timer */
>> - ali_start();
>> - }
>> - return len;
>> -}
>> -
>> -/*
>> - * ali_ioctl - handle watchdog ioctls
>> - * @file: VFS file pointer
>> - * @cmd: ioctl number
>> - * @arg: arguments to the ioctl
>> - *
>> - * Handle the watchdog ioctls supported by the ALi driver. Really
>> - * we want an extension to enable irq ack monitoring and the like
>> - */
>> -
>> -static long ali_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 |
>> - WDIOF_SETTIMEOUT |
>> - WDIOF_MAGICCLOSE,
>> - .firmware_version = 0,
>> - .identity = "ALi M1535 WatchDog Timer",
>> - };
>> -
>> - 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_SETOPTIONS:
>> - {
>> - int new_options, retval = -EINVAL;
>> -
>> - if (get_user(new_options, p))
>> - return -EFAULT;
>> - if (new_options & WDIOS_DISABLECARD) {
>> - ali_stop();
>> - retval = 0;
>> - }
>> - if (new_options & WDIOS_ENABLECARD) {
>> - ali_start();
>> - retval = 0;
>> - }
>> - return retval;
>> - }
>> - case WDIOC_KEEPALIVE:
>> - ali_keepalive();
>> - return 0;
>> - case WDIOC_SETTIMEOUT:
>> - {
>> - int new_timeout;
>> - if (get_user(new_timeout, p))
>> - return -EFAULT;
>> - if (ali_settimer(new_timeout))
>> - return -EINVAL;
>> - ali_keepalive();
>> - }
>> - /* fall through */
>> - case WDIOC_GETTIMEOUT:
>> - return put_user(timeout, p);
>> - default:
>> - return -ENOTTY;
>> - }
>> -}
>> -
>> -/*
>> - * ali_open - handle open of ali watchdog
>> - * @inode: inode from VFS
>> - * @file: file from VFS
>> - *
>> - * Open the ALi watchdog device. Ensure only one person opens it
>> - * at a time. Also start the watchdog running.
>> - */
>> -
>> -static int ali_open(struct inode *inode, struct file *file)
>> -{
>> - /* /dev/watchdog can only be opened once */
>> - if (test_and_set_bit(0, &ali_is_open))
>> - return -EBUSY;
>> -
>> - /* Activate */
>> - ali_start();
>> - return nonseekable_open(inode, file);
>> -}
>> -
>> -/*
>> - * ali_release - close an ALi watchdog
>> - * @inode: inode from VFS
>> - * @file: file from VFS
>> - *
>> - * Close the ALi watchdog device. Actual shutdown of the timer
>> - * only occurs if the magic sequence has been set.
>> - */
>> -
>> -static int ali_release(struct inode *inode, struct file *file)
>> -{
>> - /*
>> - * Shut off the timer.
>> - */
>> - if (ali_expect_release == 42)
>> - ali_stop();
>> - else {
>> - pr_crit("Unexpected close, not stopping watchdog!\n");
>> - ali_keepalive();
>> - }
>> - clear_bit(0, &ali_is_open);
>> - ali_expect_release = 0;
>> - return 0;
>> -}
>> -
>> -/*
>> - * ali_notify_sys - System down notifier
>> - *
>> - * Notifier for system down
>> - */
>> -
>> -
>> -static int ali_notify_sys(struct notifier_block *this,
>> - unsigned long code, void *unused)
>> -{
>> - if (code == SYS_DOWN || code == SYS_HALT)
>> - ali_stop(); /* Turn the WDT off */
>> - return NOTIFY_DONE;
>> -}
>> -
>> /*
>> * Data for PCI driver interface
>> *
>> @@ -361,23 +173,17 @@ static int __init ali_find_watchdog(void)
>> * Kernel Interfaces
>> */
>> -static const struct file_operations ali_fops = {
>> - .owner = THIS_MODULE,
>> - .llseek = no_llseek,
>> - .write = ali_write,
>> - .unlocked_ioctl = ali_ioctl,
>> - .open = ali_open,
>> - .release = ali_release,
>> +static struct watchdog_ops alim1535wdt_ops = {
>> + .owner = THIS_MODULE,
>> + .start = ali_start,
>> + .stop = ali_stop,
>> + .ping = ali_keepalive,
>> + .set_timeout = ali_set_timeout,
>> };
>> -static struct miscdevice ali_miscdev = {
>> - .minor = WATCHDOG_MINOR,
>> - .name = "watchdog",
>> - .fops = &ali_fops,
>> -};
>> -
>> -static struct notifier_block ali_notifier = {
>> - .notifier_call = ali_notify_sys,
>> +static struct watchdog_device alim1535wdt_wdd = {
>> + .ops = &alim1535wdt_ops,
>> + .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
>> };
>> /*
>> @@ -403,30 +209,25 @@ static int __init watchdog_init(void)
>> timeout);
>> }
>> - /* Calculate the watchdog's timeout */
>> - ali_settimer(timeout);
>> + watchdog_stop_on_reboot(&alim1535wdt_wdd);
>> +
>> + watchdog_init_timeout(&alim1535wdt_wdd, timeout, NULL);
>> +
>> + watchdog_set_nowayout(&alim1535wdt_wdd, nowayout);
>> - ret = register_reboot_notifier(&ali_notifier);
>> - if (ret != 0) {
>> - pr_err("cannot register reboot notifier (err=%d)\n", ret);
>> - goto out;
>> - }
>> + ret = watchdog_register_device(&alim1535wdt_wdd);
>> - ret = misc_register(&ali_miscdev);
>> if (ret != 0) {
>> - pr_err("cannot register miscdev on minor=%d (err=%d)\n",
>> - WATCHDOG_MINOR, ret);
>> - goto unreg_reboot;
>> + goto reboot_unreg;
>> }
>> - pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
>> - timeout, nowayout);
>> + /* Calculate the watchdog's timeout */
>> + ali_set_timeout(&alim1535wdt_wdd, timeout);
>> +
>> + return 0;
>> -out:
>> +reboot_unreg:
>> return ret;
>> -unreg_reboot:
>> - unregister_reboot_notifier(&ali_notifier);
>> - goto out;
>> }
>> /*
>> @@ -437,12 +238,8 @@ unreg_reboot:
>> static void __exit watchdog_exit(void)
>> {
>> - /* Stop the timer before we leave */
>> - ali_stop();
>> -
>> /* Deregister */
>> - misc_deregister(&ali_miscdev);
>> - unregister_reboot_notifier(&ali_notifier);
>> + watchdog_unregister_device(&alim1535wdt_wdd);
>> pci_dev_put(ali_pci);
>> }
>> @@ -451,4 +248,4 @@ module_exit(watchdog_exit);
>> MODULE_AUTHOR("Alan Cox");
>> MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
>> -MODULE_LICENSE("GPL");
>> +MODULE_LICENSE("GPL");
>>
>
>

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