362 lines
8.2 KiB
C
362 lines
8.2 KiB
C
/*
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* Copyright 2010-2011 Picochip Ltd., Jamie Iles
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* http://www.picochip.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* This file implements a driver for the Synopsys DesignWare watchdog device
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* in the many subsystems. The watchdog has 16 different timeout periods
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* and these are a function of the input clock frequency.
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*
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* The DesignWare watchdog cannot be stopped once it has been started so we
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* use a software timer to implement a ping that will keep the watchdog alive.
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* If we receive an expected close for the watchdog then we keep the timer
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* running, otherwise the timer is stopped and the watchdog will expire.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/bitops.h>
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#include <linux/clk.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/fs.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/of.h>
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#include <linux/pm.h>
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#include <linux/platform_device.h>
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#include <linux/spinlock.h>
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#include <linux/timer.h>
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#include <linux/uaccess.h>
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#include <linux/watchdog.h>
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#define WDOG_CONTROL_REG_OFFSET 0x00
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#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
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#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
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#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
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#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
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#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
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/* The maximum TOP (timeout period) value that can be set in the watchdog. */
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#define DW_WDT_MAX_TOP 15
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
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"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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#define WDT_TIMEOUT (HZ / 2)
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static struct {
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spinlock_t lock;
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void __iomem *regs;
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struct clk *clk;
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unsigned long in_use;
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unsigned long next_heartbeat;
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struct timer_list timer;
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int expect_close;
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} dw_wdt;
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static inline int dw_wdt_is_enabled(void)
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{
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return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
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WDOG_CONTROL_REG_WDT_EN_MASK;
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}
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static inline int dw_wdt_top_in_seconds(unsigned top)
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{
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/*
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* There are 16 possible timeout values in 0..15 where the number of
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* cycles is 2 ^ (16 + i) and the watchdog counts down.
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*/
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return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
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}
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static int dw_wdt_get_top(void)
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{
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int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
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return dw_wdt_top_in_seconds(top);
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}
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static inline void dw_wdt_set_next_heartbeat(void)
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{
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dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
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}
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static int dw_wdt_set_top(unsigned top_s)
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{
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int i, top_val = DW_WDT_MAX_TOP;
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/*
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* Iterate over the timeout values until we find the closest match. We
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* always look for >=.
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*/
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for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
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if (dw_wdt_top_in_seconds(i) >= top_s) {
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top_val = i;
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break;
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}
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/* Set the new value in the watchdog. */
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writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
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dw_wdt_set_next_heartbeat();
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return dw_wdt_top_in_seconds(top_val);
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}
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static void dw_wdt_keepalive(void)
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{
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writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
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WDOG_COUNTER_RESTART_REG_OFFSET);
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}
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static void dw_wdt_ping(unsigned long data)
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{
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if (time_before(jiffies, dw_wdt.next_heartbeat) ||
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(!nowayout && !dw_wdt.in_use)) {
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dw_wdt_keepalive();
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mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
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} else
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pr_crit("keepalive missed, machine will reset\n");
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}
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static int dw_wdt_open(struct inode *inode, struct file *filp)
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{
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if (test_and_set_bit(0, &dw_wdt.in_use))
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return -EBUSY;
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/* Make sure we don't get unloaded. */
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__module_get(THIS_MODULE);
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spin_lock(&dw_wdt.lock);
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if (!dw_wdt_is_enabled()) {
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/*
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* The watchdog is not currently enabled. Set the timeout to
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* the maximum and then start it.
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*/
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dw_wdt_set_top(DW_WDT_MAX_TOP);
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writel(WDOG_CONTROL_REG_WDT_EN_MASK,
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dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
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}
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dw_wdt_set_next_heartbeat();
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spin_unlock(&dw_wdt.lock);
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return nonseekable_open(inode, filp);
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}
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static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
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size_t len, loff_t *offset)
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{
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if (!len)
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return 0;
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if (!nowayout) {
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size_t i;
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dw_wdt.expect_close = 0;
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for (i = 0; i < len; ++i) {
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char c;
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if (get_user(c, buf + i))
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return -EFAULT;
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if (c == 'V') {
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dw_wdt.expect_close = 1;
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break;
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}
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}
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}
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dw_wdt_set_next_heartbeat();
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mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
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return len;
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}
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static u32 dw_wdt_time_left(void)
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{
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return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
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clk_get_rate(dw_wdt.clk);
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}
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static const struct watchdog_info dw_wdt_ident = {
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.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
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WDIOF_MAGICCLOSE,
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.identity = "Synopsys DesignWare Watchdog",
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};
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static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
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{
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unsigned long val;
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int timeout;
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user((void __user *)arg, &dw_wdt_ident,
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sizeof(dw_wdt_ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, (int __user *)arg);
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case WDIOC_KEEPALIVE:
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dw_wdt_set_next_heartbeat();
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return 0;
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case WDIOC_SETTIMEOUT:
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if (get_user(val, (int __user *)arg))
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return -EFAULT;
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timeout = dw_wdt_set_top(val);
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return put_user(timeout , (int __user *)arg);
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case WDIOC_GETTIMEOUT:
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return put_user(dw_wdt_get_top(), (int __user *)arg);
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case WDIOC_GETTIMELEFT:
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/* Get the time left until expiry. */
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if (get_user(val, (int __user *)arg))
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return -EFAULT;
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return put_user(dw_wdt_time_left(), (int __user *)arg);
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default:
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return -ENOTTY;
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}
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}
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static int dw_wdt_release(struct inode *inode, struct file *filp)
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{
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clear_bit(0, &dw_wdt.in_use);
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if (!dw_wdt.expect_close) {
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del_timer(&dw_wdt.timer);
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if (!nowayout)
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pr_crit("unexpected close, system will reboot soon\n");
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else
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pr_crit("watchdog cannot be disabled, system will reboot soon\n");
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}
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dw_wdt.expect_close = 0;
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return 0;
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}
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#ifdef CONFIG_PM_SLEEP
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static int dw_wdt_suspend(struct device *dev)
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{
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clk_disable_unprepare(dw_wdt.clk);
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return 0;
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}
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static int dw_wdt_resume(struct device *dev)
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{
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int err = clk_prepare_enable(dw_wdt.clk);
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if (err)
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return err;
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dw_wdt_keepalive();
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return 0;
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}
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#endif /* CONFIG_PM_SLEEP */
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static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
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static const struct file_operations wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.open = dw_wdt_open,
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.write = dw_wdt_write,
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.unlocked_ioctl = dw_wdt_ioctl,
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.release = dw_wdt_release
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};
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static struct miscdevice dw_wdt_miscdev = {
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.fops = &wdt_fops,
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.name = "watchdog",
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.minor = WATCHDOG_MINOR,
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};
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static int dw_wdt_drv_probe(struct platform_device *pdev)
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{
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int ret;
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struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
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if (IS_ERR(dw_wdt.regs))
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return PTR_ERR(dw_wdt.regs);
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dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(dw_wdt.clk))
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return PTR_ERR(dw_wdt.clk);
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ret = clk_prepare_enable(dw_wdt.clk);
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if (ret)
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return ret;
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spin_lock_init(&dw_wdt.lock);
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ret = misc_register(&dw_wdt_miscdev);
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if (ret)
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goto out_disable_clk;
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dw_wdt_set_next_heartbeat();
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setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
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mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
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return 0;
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out_disable_clk:
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clk_disable_unprepare(dw_wdt.clk);
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return ret;
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}
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static int dw_wdt_drv_remove(struct platform_device *pdev)
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{
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misc_deregister(&dw_wdt_miscdev);
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clk_disable_unprepare(dw_wdt.clk);
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return 0;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id dw_wdt_of_match[] = {
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{ .compatible = "snps,dw-wdt", },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
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#endif
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static struct platform_driver dw_wdt_driver = {
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.probe = dw_wdt_drv_probe,
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.remove = dw_wdt_drv_remove,
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.driver = {
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.name = "dw_wdt",
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.owner = THIS_MODULE,
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.of_match_table = of_match_ptr(dw_wdt_of_match),
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.pm = &dw_wdt_pm_ops,
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},
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};
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module_platform_driver(dw_wdt_driver);
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MODULE_AUTHOR("Jamie Iles");
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MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
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MODULE_LICENSE("GPL");
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