/*
* Copyright 2010-2011 Picochip Ltd., Jamie Iles
* http://www.picochip.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* This file implements a driver for the Synopsys DesignWare watchdog device
* in the many subsystems. The watchdog has 16 different timeout periods
* and these are a function of the input clock frequency.
*
* The DesignWare watchdog cannot be stopped once it has been started so we
* do not implement a stop function. The watchdog core will continue to send
* heartbeat requests after the watchdog device has been closed.
*/
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/watchdog.h>
#define WDOG_CONTROL_REG_OFFSET 0x00
#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
#define WDOG_CONTROL_REG_RESP_MODE_MASK 0x02
#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4
#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
/* The maximum TOP (timeout period) value that can be set in the watchdog. */
#define DW_WDT_MAX_TOP 15
#define DW_WDT_DEFAULT_SECONDS 30
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) ")");
struct dw_wdt {
void __iomem *regs;
struct clk *clk;
unsigned long rate;
struct watchdog_device wdd;
struct reset_control *rst;
/* Save/restore */
u32 control;
u32 timeout;
};
#define to_dw_wdt(wdd) container_of(wdd, struct dw_wdt, wdd)
static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
{
return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
WDOG_CONTROL_REG_WDT_EN_MASK;
}
static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
{
/*
* There are 16 possible timeout values in 0..15 where the number of
* cycles is 2 ^ (16 + i) and the watchdog counts down.
*/
return (1U << (16 + top)) / dw_wdt->rate;
}
static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
{
int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
return dw_wdt_top_in_seconds(dw_wdt, top);
}
static int dw_wdt_ping(struct watchdog_device *wdd)
{
struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
WDOG_COUNTER_RESTART_REG_OFFSET);
return 0;
}
static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
{
struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
int i, top_val = DW_WDT_MAX_TOP;
/*
* Iterate over the timeout values until we find the closest match. We
* always look for >=.
*/
for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
top_val = i;
break;
}
/*
* Set the new value in the watchdog. Some versions of dw_wdt
* have have TOPINIT in the TIMEOUT_RANGE register (as per
* CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1). On those we
* effectively get a pat of the watchdog right here.
*/
writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
return 0;
}
static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt)
{
u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
/* Disable interrupt mode; always perform system reset. */
val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
/* Enable watchdog. */
val |= WDOG_CONTROL_REG_WDT_EN_MASK;
writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
}
static int dw_wdt_start(struct watchdog_device *wdd)
{
struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
dw_wdt_set_timeout(wdd, wdd->timeout);
dw_wdt_arm_system_reset(dw_wdt);
return 0;
}
static int dw_wdt_stop(struct watchdog_device *wdd)
{
struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
if (!dw_wdt->rst) {
set_bit(WDOG_HW_RUNNING, &wdd->status);
return 0;
}
reset_control_assert(dw_wdt->rst);
reset_control_deassert(dw_wdt->rst);
return 0;
}
static int dw_wdt_restart(struct watchdog_device *wdd,
unsigned long action, void *data)
{
struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
if (dw_wdt_is_enabled(dw_wdt))
writel(WDOG_COUNTER_RESTART_KICK_VALUE,
dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
else
dw_wdt_arm_system_reset(dw_wdt);
/* wait for reset to assert... */
mdelay(500);
return 0;
}
static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
{
struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
dw_wdt->rate;
}
static const struct watchdog_info dw_wdt_ident = {
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.identity = "Synopsys DesignWare Watchdog",
};
static const struct watchdog_ops dw_wdt_ops = {
.owner = THIS_MODULE,
.start = dw_wdt_start,
.stop = dw_wdt_stop,
.ping = dw_wdt_ping,
.set_timeout = dw_wdt_set_timeout,
.get_timeleft = dw_wdt_get_timeleft,
.restart = dw_wdt_restart,
};
#ifdef CONFIG_PM_SLEEP
static int dw_wdt_suspend(struct device *dev)
{
struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
clk_disable_unprepare(dw_wdt->clk);
return 0;
}
static int dw_wdt_resume(struct device *dev)
{
struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
int err = clk_prepare_enable(dw_wdt->clk);
if (err)
return err;
writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
dw_wdt_ping(&dw_wdt->wdd);
return 0;
}
#endif /* CONFIG_PM_SLEEP */
static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
static int dw_wdt_drv_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct watchdog_device *wdd;
struct dw_wdt *dw_wdt;
int ret;
dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
if (!dw_wdt)
return -ENOMEM;
dw_wdt->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(dw_wdt->regs))
return PTR_ERR(dw_wdt->regs);
dw_wdt->clk = devm_clk_get(dev, NULL);
if (IS_ERR(dw_wdt->clk))
return PTR_ERR(dw_wdt->clk);
ret = clk_prepare_enable(dw_wdt->clk);
if (ret)
return ret;
dw_wdt->rate = clk_get_rate(dw_wdt->clk);
if (dw_wdt->rate == 0) {
ret = -EINVAL;
goto out_disable_clk;
}
dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
if (IS_ERR(dw_wdt->rst)) {
ret = PTR_ERR(dw_wdt->rst);
goto out_disable_clk;
}
reset_control_deassert(dw_wdt->rst);
wdd = &dw_wdt->wdd;
wdd->info = &dw_wdt_ident;
wdd->ops = &dw_wdt_ops;
wdd->min_timeout = 1;
wdd->max_hw_heartbeat_ms =
dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
wdd->parent = dev;
watchdog_set_drvdata(wdd, dw_wdt);
watchdog_set_nowayout(wdd, nowayout);
watchdog_init_timeout(wdd, 0, dev);
/*
* If the watchdog is already running, use its already configured
* timeout. Otherwise use the default or the value provided through
* devicetree.
*/
if (dw_wdt_is_enabled(dw_wdt)) {
wdd->timeout = dw_wdt_get_top(dw_wdt);
set_bit(WDOG_HW_RUNNING, &wdd->status);
} else {
wdd->timeout = DW_WDT_DEFAULT_SECONDS;
watchdog_init_timeout(wdd, 0, dev);
}
platform_set_drvdata(pdev, dw_wdt);
watchdog_set_restart_priority(wdd, 128);
ret = watchdog_register_device(wdd);
if (ret)
goto out_disable_clk;
return 0;
out_disable_clk:
clk_disable_unprepare(dw_wdt->clk);
return ret;
}
static int dw_wdt_drv_remove(struct platform_device *pdev)
{
struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
watchdog_unregister_device(&dw_wdt->wdd);
reset_control_assert(dw_wdt->rst);
clk_disable_unprepare(dw_wdt->clk);
return 0;
}
#ifdef CONFIG_OF
static const struct of_device_id dw_wdt_of_match[] = {
{ .compatible = "snps,dw-wdt", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
#endif
static struct platform_driver dw_wdt_driver = {
.probe = dw_wdt_drv_probe,
.remove = dw_wdt_drv_remove,
.driver = {
.name = "dw_wdt",
.of_match_table = of_match_ptr(dw_wdt_of_match),
.pm = &dw_wdt_pm_ops,
},
};
module_platform_driver(dw_wdt_driver);
MODULE_AUTHOR("Jamie Iles");
MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
MODULE_LICENSE("GPL");
