// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for Atmel SAMA5D4 Watchdog Timer
*
* Copyright (C) 2015 Atmel Corporation
*/
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
#include <linux/watchdog.h>
#include "at91sam9_wdt.h"
/* minimum and maximum watchdog timeout, in seconds */
#define MIN_WDT_TIMEOUT 1
#define MAX_WDT_TIMEOUT 16
#define WDT_DEFAULT_TIMEOUT MAX_WDT_TIMEOUT
#define WDT_SEC2TICKS(s) ((s) ? (((s) << 8) - 1) : 0)
struct sama5d4_wdt {
struct watchdog_device wdd;
void __iomem *reg_base;
u32 mr;
unsigned long last_ping;
};
static int wdt_timeout;
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(wdt_timeout, int, 0);
MODULE_PARM_DESC(wdt_timeout,
"Watchdog timeout in seconds. (default = "
__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
#define wdt_read(wdt, field) \
readl_relaxed((wdt)->reg_base + (field))
/* 4 slow clock periods is 4/32768 = 122.07µs*/
#define WDT_DELAY usecs_to_jiffies(123)
static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
{
/*
* WDT_CR and WDT_MR must not be modified within three slow clock
* periods following a restart of the watchdog performed by a write
* access in WDT_CR.
*/
while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
usleep_range(30, 125);
writel_relaxed(val, wdt->reg_base + field);
wdt->last_ping = jiffies;
}
static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
{
if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
udelay(123);
writel_relaxed(val, wdt->reg_base + field);
wdt->last_ping = jiffies;
}
static int sama5d4_wdt_start(struct watchdog_device *wdd)
{
struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
wdt->mr &= ~AT91_WDT_WDDIS;
wdt_write(wdt, AT91_WDT_MR, wdt->mr);
return 0;
}
static int sama5d4_wdt_stop(struct watchdog_device *wdd)
{
struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
wdt->mr |= AT91_WDT_WDDIS;
wdt_write(wdt, AT91_WDT_MR, wdt->mr);
return 0;
}
static int sama5d4_wdt_ping(struct watchdog_device *wdd)
{
struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
return 0;
}
static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
unsigned int timeout)
{
struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
u32 value = WDT_SEC2TICKS(timeout);
wdt->mr &= ~AT91_WDT_WDV;
wdt->mr &= ~AT91_WDT_WDD;
wdt->mr |= AT91_WDT_SET_WDV(value);
wdt->mr |= AT91_WDT_SET_WDD(value);
/*
* WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
* setting the WDDIS bit, and while it is set, the fields WDV and WDD
* must not be modified.
* If the watchdog is enabled, then the timeout can be updated. Else,
* wait that the user enables it.
*/
if (wdt_enabled)
wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
wdd->timeout = timeout;
return 0;
}
static const struct watchdog_info sama5d4_wdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
.identity = "Atmel SAMA5D4 Watchdog",
};
static const struct watchdog_ops sama5d4_wdt_ops = {
.owner = THIS_MODULE,
.start = sama5d4_wdt_start,
.stop = sama5d4_wdt_stop,
.ping = sama5d4_wdt_ping,
.set_timeout = sama5d4_wdt_set_timeout,
};
static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
{
struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
if (wdt_read(wdt, AT91_WDT_SR)) {
pr_crit("Atmel Watchdog Software Reset\n");
emergency_restart();
pr_crit("Reboot didn't succeed\n");
}
return IRQ_HANDLED;
}
static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
{
const char *tmp;
wdt->mr = AT91_WDT_WDDIS;
if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
!strcmp(tmp, "software"))
wdt->mr |= AT91_WDT_WDFIEN;
else
wdt->mr |= AT91_WDT_WDRSTEN;
if (of_property_read_bool(np, "atmel,idle-halt"))
wdt->mr |= AT91_WDT_WDIDLEHLT;
if (of_property_read_bool(np, "atmel,dbg-halt"))
wdt->mr |= AT91_WDT_WDDBGHLT;
return 0;
}
static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
{
u32 reg;
/*
* When booting and resuming, the bootloader may have changed the
* watchdog configuration.
* If the watchdog is already running, we can safely update it.
* Else, we have to disable it properly.
*/
if (wdt_enabled) {
wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
} else {
reg = wdt_read(wdt, AT91_WDT_MR);
if (!(reg & AT91_WDT_WDDIS))
wdt_write_nosleep(wdt, AT91_WDT_MR,
reg | AT91_WDT_WDDIS);
}
return 0;
}
static int sama5d4_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct watchdog_device *wdd;
struct sama5d4_wdt *wdt;
void __iomem *regs;
u32 irq = 0;
u32 timeout;
int ret;
wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
wdd = &wdt->wdd;
wdd->timeout = WDT_DEFAULT_TIMEOUT;
wdd->info = &sama5d4_wdt_info;
wdd->ops = &sama5d4_wdt_ops;
wdd->min_timeout = MIN_WDT_TIMEOUT;
wdd->max_timeout = MAX_WDT_TIMEOUT;
wdt->last_ping = jiffies;
watchdog_set_drvdata(wdd, wdt);
regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(regs))
return PTR_ERR(regs);
wdt->reg_base = regs;
irq = irq_of_parse_and_map(dev->of_node, 0);
if (!irq)
dev_warn(dev, "failed to get IRQ from DT\n");
ret = of_sama5d4_wdt_init(dev->of_node, wdt);
if (ret)
return ret;
if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
IRQF_SHARED | IRQF_IRQPOLL |
IRQF_NO_SUSPEND, pdev->name, pdev);
if (ret) {
dev_err(dev, "cannot register interrupt handler\n");
return ret;
}
}
watchdog_init_timeout(wdd, wdt_timeout, dev);
timeout = WDT_SEC2TICKS(wdd->timeout);
wdt->mr |= AT91_WDT_SET_WDD(timeout);
wdt->mr |= AT91_WDT_SET_WDV(timeout);
ret = sama5d4_wdt_init(wdt);
if (ret)
return ret;
watchdog_set_nowayout(wdd, nowayout);
watchdog_stop_on_unregister(wdd);
ret = devm_watchdog_register_device(dev, wdd);
if (ret) {
dev_err(dev, "failed to register watchdog device\n");
return ret;
}
platform_set_drvdata(pdev, wdt);
dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
wdd->timeout, nowayout);
return 0;
}
static const struct of_device_id sama5d4_wdt_of_match[] = {
{ .compatible = "atmel,sama5d4-wdt", },
{ }
};
MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
#ifdef CONFIG_PM_SLEEP
static int sama5d4_wdt_resume(struct device *dev)
{
struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
/*
* FIXME: writing MR also pings the watchdog which may not be desired.
* This should only be done when the registers are lost on suspend but
* there is no way to get this information right now.
*/
sama5d4_wdt_init(wdt);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
sama5d4_wdt_resume);
static struct platform_driver sama5d4_wdt_driver = {
.probe = sama5d4_wdt_probe,
.driver = {
.name = "sama5d4_wdt",
.pm = &sama5d4_wdt_pm_ops,
.of_match_table = sama5d4_wdt_of_match,
}
};
module_platform_driver(sama5d4_wdt_driver);
MODULE_AUTHOR("Atmel Corporation");
MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
MODULE_LICENSE("GPL v2");
