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rtc: watchdog support for rtc-m41t80 driver
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Add a watchdog driver interface to rtc-m41t80 driver.  This is derived from
works by Alexander Bigga <ab@mycable.de>

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Alexander Bigga <ab@mycable.de>
Cc: David Brownell <david-b@pacbell.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Atsushi Nemoto authored and Linus Torvalds committed Jul 17, 2007
1 parent caaff56 commit 617780d
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7 changes: 7 additions & 0 deletions drivers/rtc/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -224,6 +224,13 @@ config RTC_DRV_M41T80
This driver can also be built as a module. If so, the module
will be called rtc-m41t80.

config RTC_DRV_M41T80_WDT
bool "ST M41T80 series RTC watchdog timer"
depends on RTC_DRV_M41T80
help
If you say Y here you will get support for the
watchdog timer in ST M41T80 RTC chips series.

comment "SPI RTC drivers"
depends on RTC_CLASS && SPI_MASTER

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288 changes: 288 additions & 0 deletions drivers/rtc/rtc-m41t80.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,13 @@
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#ifdef CONFIG_RTC_DRV_M41T80_WDT
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/ioctl.h>
#endif

#define M41T80_REG_SSEC 0
#define M41T80_REG_SEC 1
Expand Down Expand Up @@ -480,6 +487,268 @@ static int m41t80_sysfs_register(struct device *dev)
}
#endif

#ifdef CONFIG_RTC_DRV_M41T80_WDT
/*
*****************************************************************************
*
* Watchdog Driver
*
*****************************************************************************
*/
static struct i2c_client *save_client;

/* Default margin */
#define WD_TIMO 60 /* 1..31 seconds */

static int wdt_margin = WD_TIMO;
module_param(wdt_margin, int, 0);
MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");

static unsigned long wdt_is_open;
static int boot_flag;

/**
* wdt_ping:
*
* Reload counter one with the watchdog timeout. We don't bother reloading
* the cascade counter.
*/
static void wdt_ping(void)
{
unsigned char i2c_data[2];
struct i2c_msg msgs1[1] = {
{
.addr = save_client->addr,
.flags = 0,
.len = 2,
.buf = i2c_data,
},
};
i2c_data[0] = 0x09; /* watchdog register */

if (wdt_margin > 31)
i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
else
/*
* WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
*/
i2c_data[1] = wdt_margin<<2 | 0x82;

i2c_transfer(save_client->adapter, msgs1, 1);
}

/**
* wdt_disable:
*
* disables watchdog.
*/
static void wdt_disable(void)
{
unsigned char i2c_data[2], i2c_buf[0x10];
struct i2c_msg msgs0[2] = {
{
.addr = save_client->addr,
.flags = 0,
.len = 1,
.buf = i2c_data,
},
{
.addr = save_client->addr,
.flags = I2C_M_RD,
.len = 1,
.buf = i2c_buf,
},
};
struct i2c_msg msgs1[1] = {
{
.addr = save_client->addr,
.flags = 0,
.len = 2,
.buf = i2c_data,
},
};

i2c_data[0] = 0x09;
i2c_transfer(save_client->adapter, msgs0, 2);

i2c_data[0] = 0x09;
i2c_data[1] = 0x00;
i2c_transfer(save_client->adapter, msgs1, 1);
}

/**
* wdt_write:
* @file: file handle to the watchdog
* @buf: buffer to write (unused as data does not matter here
* @count: count of bytes
* @ppos: pointer to the position to write. No seeks allowed
*
* A write to a watchdog device is defined as a keepalive signal. Any
* write of data will do, as we we don't define content meaning.
*/
static ssize_t wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
/* Can't seek (pwrite) on this device
if (ppos != &file->f_pos)
return -ESPIPE;
*/
if (count) {
wdt_ping();
return 1;
}
return 0;
}

static ssize_t wdt_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}

/**
* wdt_ioctl:
* @inode: inode of the device
* @file: file handle to the device
* @cmd: watchdog command
* @arg: argument pointer
*
* The watchdog API defines a common set of functions for all watchdogs
* according to their available features. We only actually usefully support
* querying capabilities and current status.
*/
static int wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
int new_margin, rv;
static struct watchdog_info ident = {
.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
WDIOF_SETTIMEOUT,
.firmware_version = 1,
.identity = "M41T80 WTD"
};

switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user((struct watchdog_info __user *)arg, &ident,
sizeof(ident)) ? -EFAULT : 0;

case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(boot_flag, (int __user *)arg);
case WDIOC_KEEPALIVE:
wdt_ping();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, (int __user *)arg))
return -EFAULT;
/* Arbitrary, can't find the card's limits */
if (new_margin < 1 || new_margin > 124)
return -EINVAL;
wdt_margin = new_margin;
wdt_ping();
/* Fall */
case WDIOC_GETTIMEOUT:
return put_user(wdt_margin, (int __user *)arg);

case WDIOC_SETOPTIONS:
if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
return -EFAULT;

if (rv & WDIOS_DISABLECARD) {
printk(KERN_INFO
"rtc-m41t80: disable watchdog\n");
wdt_disable();
}

if (rv & WDIOS_ENABLECARD) {
printk(KERN_INFO
"rtc-m41t80: enable watchdog\n");
wdt_ping();
}

return -EINVAL;
}
return -ENOTTY;
}

/**
* wdt_open:
* @inode: inode of device
* @file: file handle to device
*
*/
static int wdt_open(struct inode *inode, struct file *file)
{
if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
if (test_and_set_bit(0, &wdt_is_open))
return -EBUSY;
/*
* Activate
*/
wdt_is_open = 1;
return 0;
}
return -ENODEV;
}

/**
* wdt_close:
* @inode: inode to board
* @file: file handle to board
*
*/
static int wdt_release(struct inode *inode, struct file *file)
{
if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
clear_bit(0, &wdt_is_open);
return 0;
}

/**
* notify_sys:
* @this: our notifier block
* @code: the event being reported
* @unused: unused
*
* Our notifier is called on system shutdowns. We want to turn the card
* off at reboot otherwise the machine will reboot again during memory
* test or worse yet during the following fsck. This would suck, in fact
* trust me - if it happens it does suck.
*/
static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
/* Disable Watchdog */
wdt_disable();
return NOTIFY_DONE;
}

static const struct file_operations wdt_fops = {
.owner = THIS_MODULE,
.read = wdt_read,
.ioctl = wdt_ioctl,
.write = wdt_write,
.open = wdt_open,
.release = wdt_release,
};

static struct miscdevice wdt_dev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wdt_fops,
};

/*
* The WDT card needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block wdt_notifier = {
.notifier_call = wdt_notify_sys,
};
#endif /* CONFIG_RTC_DRV_M41T80_WDT */

/*
*****************************************************************************
*
Expand Down Expand Up @@ -572,6 +841,19 @@ static int m41t80_probe(struct i2c_client *client)
if (rc)
goto exit;

#ifdef CONFIG_RTC_DRV_M41T80_WDT
if (chip->features & M41T80_FEATURE_HT) {
rc = misc_register(&wdt_dev);
if (rc)
goto exit;
rc = register_reboot_notifier(&wdt_notifier);
if (rc) {
misc_deregister(&wdt_dev);
goto exit;
}
save_client = client;
}
#endif
return 0;

st_err:
Expand All @@ -595,6 +877,12 @@ static int m41t80_remove(struct i2c_client *client)
struct m41t80_data *clientdata = i2c_get_clientdata(client);
struct rtc_device *rtc = clientdata->rtc;

#ifdef CONFIG_RTC_DRV_M41T80_WDT
if (clientdata->chip->features & M41T80_FEATURE_HT) {
misc_deregister(&wdt_dev);
unregister_reboot_notifier(&wdt_notifier);
}
#endif
if (rtc)
rtc_device_unregister(rtc);
kfree(clientdata);
Expand Down

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