mt7621_wdt.c
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/*
* Ralink MT7621/MT7628 built-in hardware watchdog timer
*
* Copyright (C) 2014 John Crispin <john@phrozen.org>
*
* This driver was based on: drivers/watchdog/rt2880_wdt.c
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#include <linux/clk.h>
#include <linux/reset.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/watchdog.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <asm/mach-ralink/ralink_regs.h>
#define SYSC_RSTSTAT 0x38
#define WDT_RST_CAUSE BIT(1)
#define RALINK_WDT_TIMEOUT 30
#define TIMER_REG_TMRSTAT 0x00
#define TIMER_REG_TMR1LOAD 0x24
#define TIMER_REG_TMR1CTL 0x20
#define TMR1CTL_ENABLE BIT(7)
#define TMR1CTL_RESTART BIT(9)
#define TMR1CTL_PRESCALE_SHIFT 16
static void __iomem *mt7621_wdt_base;
static struct reset_control *mt7621_wdt_reset;
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static inline void rt_wdt_w32(unsigned reg, u32 val)
{
iowrite32(val, mt7621_wdt_base + reg);
}
static inline u32 rt_wdt_r32(unsigned reg)
{
return ioread32(mt7621_wdt_base + reg);
}
static int mt7621_wdt_ping(struct watchdog_device *w)
{
rt_wdt_w32(TIMER_REG_TMRSTAT, TMR1CTL_RESTART);
return 0;
}
static int mt7621_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
{
w->timeout = t;
rt_wdt_w32(TIMER_REG_TMR1LOAD, t * 1000);
mt7621_wdt_ping(w);
return 0;
}
static int mt7621_wdt_start(struct watchdog_device *w)
{
u32 t;
/* set the prescaler to 1ms == 1000us */
rt_wdt_w32(TIMER_REG_TMR1CTL, 1000 << TMR1CTL_PRESCALE_SHIFT);
mt7621_wdt_set_timeout(w, w->timeout);
t = rt_wdt_r32(TIMER_REG_TMR1CTL);
t |= TMR1CTL_ENABLE;
rt_wdt_w32(TIMER_REG_TMR1CTL, t);
return 0;
}
static int mt7621_wdt_stop(struct watchdog_device *w)
{
u32 t;
mt7621_wdt_ping(w);
t = rt_wdt_r32(TIMER_REG_TMR1CTL);
t &= ~TMR1CTL_ENABLE;
rt_wdt_w32(TIMER_REG_TMR1CTL, t);
return 0;
}
static int mt7621_wdt_bootcause(void)
{
if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
return WDIOF_CARDRESET;
return 0;
}
static const struct watchdog_info mt7621_wdt_info = {
.identity = "Mediatek Watchdog",
.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
};
static const struct watchdog_ops mt7621_wdt_ops = {
.owner = THIS_MODULE,
.start = mt7621_wdt_start,
.stop = mt7621_wdt_stop,
.ping = mt7621_wdt_ping,
.set_timeout = mt7621_wdt_set_timeout,
};
static struct watchdog_device mt7621_wdt_dev = {
.info = &mt7621_wdt_info,
.ops = &mt7621_wdt_ops,
.min_timeout = 1,
.max_timeout = 0xfffful / 1000,
};
static int mt7621_wdt_probe(struct platform_device *pdev)
{
struct resource *res;
int ret;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
mt7621_wdt_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(mt7621_wdt_base))
return PTR_ERR(mt7621_wdt_base);
mt7621_wdt_reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
if (!IS_ERR(mt7621_wdt_reset))
reset_control_deassert(mt7621_wdt_reset);
mt7621_wdt_dev.bootstatus = mt7621_wdt_bootcause();
watchdog_init_timeout(&mt7621_wdt_dev, mt7621_wdt_dev.max_timeout,
&pdev->dev);
watchdog_set_nowayout(&mt7621_wdt_dev, nowayout);
ret = watchdog_register_device(&mt7621_wdt_dev);
return 0;
}
static int mt7621_wdt_remove(struct platform_device *pdev)
{
watchdog_unregister_device(&mt7621_wdt_dev);
return 0;
}
static void mt7621_wdt_shutdown(struct platform_device *pdev)
{
mt7621_wdt_stop(&mt7621_wdt_dev);
}
static const struct of_device_id mt7621_wdt_match[] = {
{ .compatible = "mediatek,mt7621-wdt" },
{},
};
MODULE_DEVICE_TABLE(of, mt7621_wdt_match);
static struct platform_driver mt7621_wdt_driver = {
.probe = mt7621_wdt_probe,
.remove = mt7621_wdt_remove,
.shutdown = mt7621_wdt_shutdown,
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = mt7621_wdt_match,
},
};
module_platform_driver(mt7621_wdt_driver);
MODULE_DESCRIPTION("MediaTek MT762x hardware watchdog driver");
MODULE_AUTHOR("John Crispin <john@phrozen.org");
MODULE_LICENSE("GPL v2");