Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=617780d290bd6eb2b260928c6acff5b7c6084154
Commit:     617780d290bd6eb2b260928c6acff5b7c6084154
Parent:     caaff562e0ba44a7991ee8322fa4a6891d939757
Author:     Atsushi Nemoto <[EMAIL PROTECTED]>
AuthorDate: Tue Jul 17 04:05:04 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Tue Jul 17 10:23:09 2007 -0700

    rtc: watchdog support for rtc-m41t80 driver
    
    Add a watchdog driver interface to rtc-m41t80 driver.  This is derived from
    works by Alexander Bigga <[EMAIL PROTECTED]>
    
    Signed-off-by: Atsushi Nemoto <[EMAIL PROTECTED]>
    Signed-off-by: Alexander Bigga <[EMAIL PROTECTED]>
    Cc: David Brownell <[EMAIL PROTECTED]>
    Acked-by: Alessandro Zummo <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 drivers/rtc/Kconfig      |    7 +
 drivers/rtc/rtc-m41t80.c |  288 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 295 insertions(+), 0 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index fb9ce74..3593233 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -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
 
diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index 4875a44..80c4a84 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -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
@@ -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 */
+
 /*
  *****************************************************************************
  *
@@ -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:
@@ -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);
-
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