lkml.org 
[lkml]   [2019]   [Aug]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v4] watchdog: alim1535: Rewriting of alim1535 driver to use watchdog subsystem
Date
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>

---
drivers/watchdog/Kconfig | 1 +
drivers/watchdog/alim1535_wdt.c | 294 ++++++--------------------------
2 files changed, 50 insertions(+), 245 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..747ba12c 100644
--- a/drivers/watchdog/alim1535_wdt.c
+++ b/drivers/watchdog/alim1535_wdt.c
@@ -12,29 +12,20 @@
#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>

#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;
+static int timeout;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. (0 < timeout < 18000, default="
@@ -53,18 +44,15 @@ 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;
}

/*
@@ -73,225 +61,53 @@ 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);
-}
-
-/*
- * ali_keepalive - send a keepalive to the watchdog
- *
- * Send a keepalive to the timer (actually we restart the timer).
- */
-
-static void ali_keepalive(void)
-{
- ali_start();
+ 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
+ spin_lock(&ali_lock);
+ if (t < 0) {
+ spin_unlock(&ali_lock);
return -EINVAL;
-
- timeout = t;
- return 0;
-}
-
-/*
- * /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;
+ } else if (t < 60) {
+ ali_timeout_bits = t | (1 << 6);
}
- 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();
+ } else if (t < 3600) {
+ ali_timeout_bits = (t / 60) | (1 << 7);
}
- /* fall through */
- case WDIOC_GETTIMEOUT:
- return put_user(timeout, p);
- default:
- return -ENOTTY;
+ } else if (t < 18000) {
+ ali_timeout_bits = (t / 300) | (1 << 6) | (1 << 7);
}
-}
-
-/*
- * 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();
+ spin_unlock(&ali_lock);
+ return -EINVAL;
}
- clear_bit(0, &ali_is_open);
- ali_expect_release = 0;
+ wdd->timeout = t;
+ spin_unlock(&ali_lock);
return 0;
}

/*
- * ali_notify_sys - System down notifier
- *
- * Notifier for system down
+ * /dev/watchdog handling
*/

-
-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 +177,25 @@ 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,
+ .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 const struct watchdog_info alim1535wdt_ident = {
+ .firmware_version = 0,
+ .identity = "ALi M1535 Watchdog",
+ };
+
+static struct watchdog_device alim1535wdt_wdd = {
+ .ops = &alim1535wdt_ops,
+ .info = &alim1535wdt_ident,
+ .status = WATCHDOG_NOWAYOUT_INIT_STATUS,
+ .min_timeout = 1,
+ .max_timeout = 18000,
+
};

/*
@@ -403,30 +221,20 @@ 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;
+ return ret;
}
+
+ return 0;

- pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
- timeout, nowayout);
-
-out:
- return ret;
-unreg_reboot:
- unregister_reboot_notifier(&ali_notifier);
- goto out;
}

/*
@@ -437,12 +245,8 @@ 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 +255,4 @@ module_exit(watchdog_exit);

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL");
--
2.17.1
\
 
 \ /
  Last update: 2019-08-02 06:12    [W:0.059 / U:1.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site