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linux/drivers/watchdog/wm831x_wdt.c
Mark Brown 076bad7c4d watchdog: Handle multiple wm831x watchdogs being registered 
Due to the whole single instance based watchdog API we use static data
for the wm831x watchdog which means that if the system tries to register
a second one we end up trying to register the same miscdevice again,
corrupting the miscdevice list. Work around this by checking for duplicate
registrations until we get a watchdog core.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
2011-06-28 07:42:16 +00:00

447 lines
9.2 KiB
C
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/*
* Watchdog driver for the wm831x PMICs
*
* Copyright (C) 2009 Wolfson Microelectronics
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>
#include <linux/mfd/wm831x/core.h>
#include <linux/mfd/wm831x/pdata.h>
#include <linux/mfd/wm831x/watchdog.h>
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static unsigned long wm831x_wdt_users;
static struct miscdevice wm831x_wdt_miscdev;
static int wm831x_wdt_expect_close;
static DEFINE_MUTEX(wdt_mutex);
static struct wm831x *wm831x;
static unsigned int update_gpio;
static unsigned int update_state;
/* We can't use the sub-second values here but they're included
* for completeness. */
static struct {
int time; /* Seconds */
u16 val; /* WDOG_TO value */
} wm831x_wdt_cfgs[] = {
{ 1, 2 },
{ 2, 3 },
{ 4, 4 },
{ 8, 5 },
{ 16, 6 },
{ 32, 7 },
{ 33, 7 }, /* Actually 32.768s so include both, others round down */
};
static int wm831x_wdt_set_timeout(struct wm831x *wm831x, u16 value)
{
int ret;
mutex_lock(&wdt_mutex);
ret = wm831x_reg_unlock(wm831x);
if (ret == 0) {
ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
WM831X_WDOG_TO_MASK, value);
wm831x_reg_lock(wm831x);
} else {
dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
ret);
}
mutex_unlock(&wdt_mutex);
return ret;
}
static int wm831x_wdt_start(struct wm831x *wm831x)
{
int ret;
mutex_lock(&wdt_mutex);
ret = wm831x_reg_unlock(wm831x);
if (ret == 0) {
ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
WM831X_WDOG_ENA, WM831X_WDOG_ENA);
wm831x_reg_lock(wm831x);
} else {
dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
ret);
}
mutex_unlock(&wdt_mutex);
return ret;
}
static int wm831x_wdt_stop(struct wm831x *wm831x)
{
int ret;
mutex_lock(&wdt_mutex);
ret = wm831x_reg_unlock(wm831x);
if (ret == 0) {
ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
WM831X_WDOG_ENA, 0);
wm831x_reg_lock(wm831x);
} else {
dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
ret);
}
mutex_unlock(&wdt_mutex);
return ret;
}
static int wm831x_wdt_kick(struct wm831x *wm831x)
{
int ret;
u16 reg;
mutex_lock(&wdt_mutex);
if (update_gpio) {
gpio_set_value_cansleep(update_gpio, update_state);
update_state = !update_state;
ret = 0;
goto out;
}
reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
if (!(reg & WM831X_WDOG_RST_SRC)) {
dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
ret = -EINVAL;
goto out;
}
reg |= WM831X_WDOG_RESET;
ret = wm831x_reg_unlock(wm831x);
if (ret == 0) {
ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
wm831x_reg_lock(wm831x);
} else {
dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
ret);
}
out:
mutex_unlock(&wdt_mutex);
return ret;
}
static int wm831x_wdt_open(struct inode *inode, struct file *file)
{
int ret;
if (!wm831x)
return -ENODEV;
if (test_and_set_bit(0, &wm831x_wdt_users))
return -EBUSY;
ret = wm831x_wdt_start(wm831x);
if (ret != 0)
return ret;
return nonseekable_open(inode, file);
}
static int wm831x_wdt_release(struct inode *inode, struct file *file)
{
if (wm831x_wdt_expect_close)
wm831x_wdt_stop(wm831x);
else {
dev_warn(wm831x->dev, "Watchdog device closed uncleanly\n");
wm831x_wdt_kick(wm831x);
}
clear_bit(0, &wm831x_wdt_users);
return 0;
}
static ssize_t wm831x_wdt_write(struct file *file,
const char __user *data, size_t count,
loff_t *ppos)
{
size_t i;
if (count) {
wm831x_wdt_kick(wm831x);
if (!nowayout) {
/* In case it was set long ago */
wm831x_wdt_expect_close = 0;
/* scan to see whether or not we got the magic
character */
for (i = 0; i != count; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
wm831x_wdt_expect_close = 42;
}
}
}
return count;
}
static const struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.identity = "WM831x Watchdog",
};
static long wm831x_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = -ENOTTY, time, i;
void __user *argp = (void __user *)arg;
int __user *p = argp;
u16 reg;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
ret = put_user(0, p);
break;
case WDIOC_SETOPTIONS:
{
int options;
if (get_user(options, p))
return -EFAULT;
ret = -EINVAL;
/* Setting both simultaneously means at least one must fail */
if (options == WDIOS_DISABLECARD)
ret = wm831x_wdt_start(wm831x);
if (options == WDIOS_ENABLECARD)
ret = wm831x_wdt_stop(wm831x);
break;
}
case WDIOC_KEEPALIVE:
ret = wm831x_wdt_kick(wm831x);
break;
case WDIOC_SETTIMEOUT:
ret = get_user(time, p);
if (ret)
break;
if (time == 0) {
if (nowayout)
ret = -EINVAL;
else
wm831x_wdt_stop(wm831x);
break;
}
for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
if (wm831x_wdt_cfgs[i].time == time)
break;
if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
ret = -EINVAL;
else
ret = wm831x_wdt_set_timeout(wm831x,
wm831x_wdt_cfgs[i].val);
break;
case WDIOC_GETTIMEOUT:
reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
reg &= WM831X_WDOG_TO_MASK;
for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
if (wm831x_wdt_cfgs[i].val == reg)
break;
if (i == ARRAY_SIZE(wm831x_wdt_cfgs)) {
dev_warn(wm831x->dev,
"Unknown watchdog configuration: %x\n", reg);
ret = -EINVAL;
} else
ret = put_user(wm831x_wdt_cfgs[i].time, p);
}
return ret;
}
static const struct file_operations wm831x_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = wm831x_wdt_write,
.unlocked_ioctl = wm831x_wdt_ioctl,
.open = wm831x_wdt_open,
.release = wm831x_wdt_release,
};
static struct miscdevice wm831x_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wm831x_wdt_fops,
};
static int __devinit wm831x_wdt_probe(struct platform_device *pdev)
{
struct wm831x_pdata *chip_pdata;
struct wm831x_watchdog_pdata *pdata;
int reg, ret;
if (wm831x) {
dev_err(&pdev->dev, "wm831x watchdog already registered\n");
return -EBUSY;
}
wm831x = dev_get_drvdata(pdev->dev.parent);
ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
if (ret < 0) {
dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
ret);
goto err;
}
reg = ret;
if (reg & WM831X_WDOG_DEBUG)
dev_warn(wm831x->dev, "Watchdog is paused\n");
/* Apply any configuration */
if (pdev->dev.parent->platform_data) {
chip_pdata = pdev->dev.parent->platform_data;
pdata = chip_pdata->watchdog;
} else {
pdata = NULL;
}
if (pdata) {
reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
WM831X_WDOG_RST_SRC);
reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
if (pdata->update_gpio) {
ret = gpio_request(pdata->update_gpio,
"Watchdog update");
if (ret < 0) {
dev_err(wm831x->dev,
"Failed to request update GPIO: %d\n",
ret);
goto err;
}
ret = gpio_direction_output(pdata->update_gpio, 0);
if (ret != 0) {
dev_err(wm831x->dev,
"gpio_direction_output returned: %d\n",
ret);
goto err_gpio;
}
update_gpio = pdata->update_gpio;
/* Make sure the watchdog takes hardware updates */
reg |= WM831X_WDOG_RST_SRC;
}
ret = wm831x_reg_unlock(wm831x);
if (ret == 0) {
ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
wm831x_reg_lock(wm831x);
} else {
dev_err(wm831x->dev,
"Failed to unlock security key: %d\n", ret);
goto err_gpio;
}
}
wm831x_wdt_miscdev.parent = &pdev->dev;
ret = misc_register(&wm831x_wdt_miscdev);
if (ret != 0) {
dev_err(wm831x->dev, "Failed to register miscdev: %d\n", ret);
goto err_gpio;
}
return 0;
err_gpio:
if (update_gpio) {
gpio_free(update_gpio);
update_gpio = 0;
}
err:
return ret;
}
static int __devexit wm831x_wdt_remove(struct platform_device *pdev)
{
if (update_gpio) {
gpio_free(update_gpio);
update_gpio = 0;
}
misc_deregister(&wm831x_wdt_miscdev);
return 0;
}
static struct platform_driver wm831x_wdt_driver = {
.probe = wm831x_wdt_probe,
.remove = __devexit_p(wm831x_wdt_remove),
.driver = {
.name = "wm831x-watchdog",
},
};
static int __init wm831x_wdt_init(void)
{
return platform_driver_register(&wm831x_wdt_driver);
}
module_init(wm831x_wdt_init);
static void __exit wm831x_wdt_exit(void)
{
platform_driver_unregister(&wm831x_wdt_driver);
}
module_exit(wm831x_wdt_exit);
MODULE_AUTHOR("Mark Brown");
MODULE_DESCRIPTION("WM831x Watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:wm831x-watchdog");
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