--- /dev/null
+/*
+ * Watchdog driver for Cirrus Logic EP93xx family of devices.
+ *
+ * Copyright (c) 2004 Ray Lehtiniemi
+ * Copyright (c) 2006 Tower Technologies
+ * Based on ep93xx driver, bits from alim7101_wdt.c
+ *
+ * Authors: Ray Lehtiniemi <rayl@mail.com>,
+ * Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This watchdog fires after 250msec, which is a too short interval
+ * for us to rely on the user space daemon alone. So we ping the
+ * wdt each ~200msec and eventually stop doing it if the user space
+ * daemon dies.
+ *
+ * TODO:
+ *
+ * - Test last reset from watchdog status
+ * - Add a few missing ioctls
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/timer.h>
+
+#include <asm/hardware.h>
+#include <asm/uaccess.h>
+
+#define WDT_VERSION "0.3"
+#define PFX "ep93xx_wdt: "
+
+/* default timeout (secs) */
+#define WDT_TIMEOUT 30
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+static int timeout = WDT_TIMEOUT;
+
+static struct timer_list timer;
+static unsigned long next_heartbeat;
+static unsigned long wdt_status;
+static unsigned long boot_status;
+
+#define WDT_IN_USE 0
+#define WDT_OK_TO_CLOSE 1
+
+#define EP93XX_WDT_REG(x) (EP93XX_WATCHDOG_BASE + (x))
+#define EP93XX_WDT_WATCHDOG EP93XX_WDT_REG(0x00)
+#define EP93XX_WDT_WDSTATUS EP93XX_WDT_REG(0x04)
+
+/* reset the wdt every ~200ms */
+#define WDT_INTERVAL (HZ/5)
+
+static void wdt_enable(void)
+{
+ __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
+}
+
+static void wdt_disable(void)
+{
+ __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
+}
+
+static inline void wdt_ping(void)
+{
+ __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
+}
+
+static void wdt_startup(void)
+{
+ next_heartbeat = jiffies + (timeout * HZ);
+
+ wdt_enable();
+ mod_timer(&timer, jiffies + WDT_INTERVAL);
+}
+
+static void wdt_shutdown(void)
+{
+ del_timer_sync(&timer);
+ wdt_disable();
+}
+
+static void wdt_keepalive(void)
+{
+ /* user land ping */
+ next_heartbeat = jiffies + (timeout * HZ);
+}
+
+static int ep93xx_wdt_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(WDT_IN_USE, &wdt_status))
+ return -EBUSY;
+
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+ wdt_startup();
+
+ return nonseekable_open(inode, file);
+}
+
+static ssize_t
+ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
+ loff_t *ppos)
+{
+ /* Can't seek (pwrite) on this device */
+ if (*ppos != file->f_pos)
+ return -ESPIPE;
+
+ if (len) {
+ if (!nowayout) {
+ size_t i;
+
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+ for (i = 0; i != len; i++) {
+ char c;
+
+ if (get_user(c, data + i))
+ return -EFAULT;
+
+ if (c == 'V')
+ set_bit(WDT_OK_TO_CLOSE, &wdt_status);
+ else
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+ }
+ }
+ wdt_keepalive();
+ }
+
+ return len;
+}
+
+static struct watchdog_info ident = {
+ .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
+ .identity = "EP93xx Watchdog",
+};
+
+static int
+ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ int ret = -ENOIOCTLCMD;
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
+ sizeof(ident)) ? -EFAULT : 0;
+ break;
+
+ case WDIOC_GETSTATUS:
+ ret = put_user(0, (int __user *)arg);
+ break;
+
+ case WDIOC_GETBOOTSTATUS:
+ ret = put_user(boot_status, (int __user *)arg);
+ break;
+
+ case WDIOC_GETTIMEOUT:
+ /* actually, it is 0.250 seconds.... */
+ ret = put_user(1, (int __user *)arg);
+ break;
+
+ case WDIOC_KEEPALIVE:
+ wdt_keepalive();
+ ret = 0;
+ break;
+ }
+ return ret;
+}
+
+static int ep93xx_wdt_release(struct inode *inode, struct file *file)
+{
+ if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
+ wdt_shutdown();
+ else
+ printk(KERN_CRIT PFX "Device closed unexpectedly - "
+ "timer will not stop\n");
+
+ clear_bit(WDT_IN_USE, &wdt_status);
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+ return 0;
+}
+
+static struct file_operations ep93xx_wdt_fops = {
+ .owner = THIS_MODULE,
+ .write = ep93xx_wdt_write,
+ .ioctl = ep93xx_wdt_ioctl,
+ .open = ep93xx_wdt_open,
+ .release = ep93xx_wdt_release,
+};
+
+static struct miscdevice ep93xx_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &ep93xx_wdt_fops,
+};
+
+static void ep93xx_timer_ping(unsigned long data)
+{
+ if (time_before(jiffies, next_heartbeat))
+ wdt_ping();
+
+ /* Re-set the timer interval */
+ mod_timer(&timer, jiffies + WDT_INTERVAL);
+}
+
+static int __init ep93xx_wdt_init(void)
+{
+ int err;
+
+ err = misc_register(&ep93xx_wdt_miscdev);
+
+ boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
+
+ printk(KERN_INFO PFX "EP93XX watchdog, driver version "
+ WDT_VERSION "%s\n",
+ (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
+ ? " (nCS1 disable detected)" : "");
+
+ if (timeout < 1 || timeout > 3600) {
+ timeout = WDT_TIMEOUT;
+ printk(KERN_INFO PFX
+ "timeout value must be 1<=x<=3600, using %d\n",
+ timeout);
+ }
+
+ setup_timer(&timer, ep93xx_timer_ping, 1);
+ return err;
+}
+
+static void __exit ep93xx_wdt_exit(void)
+{
+ wdt_shutdown();
+ misc_deregister(&ep93xx_wdt_miscdev);
+}
+
+module_init(ep93xx_wdt_init);
+module_exit(ep93xx_wdt_exit);
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
+
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
+ "Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("EP93xx Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(WDT_VERSION);
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
projects / GitHub / LineageOS / android_kernel_samsung_universal7580.git / commitdiff