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- // 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_SET_WDV(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(WDT_SEC2TICKS(MAX_WDT_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)
- 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_suspend_late(struct device *dev)
- {
- struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
- if (watchdog_active(&wdt->wdd))
- sama5d4_wdt_stop(&wdt->wdd);
- return 0;
- }
- static int sama5d4_wdt_resume_early(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);
- if (watchdog_active(&wdt->wdd))
- sama5d4_wdt_start(&wdt->wdd);
- return 0;
- }
- #endif
- static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
- SET_LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
- sama5d4_wdt_resume_early)
- };
- 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");
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