rtc: watchdog support for rtc-m41t80 driver
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>
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 @@
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 @@
}
#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 @@
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 @@
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);
