[PATCH 2/3] watchdog: sama5d4_wdt: Refactor the driver
Alexandre Belloni
alexandre.belloni at bootlin.com
Fri Feb 27 00:05:42 PST 2026
On 27/02/2026 13:01:15+0530, Balakrishnan Sambath wrote:
> From: Andrei Simion <andrei.simion at microchip.com>
>
> This patch cleans up and refactors the Atmel SAMA5D4 Watchdog Driver
> to be more readable and to fixup Reset issue introduced
> by commit 266da53c35fc ("watchdog: sama5d4: readout initial state").
>
> Signed-off-by: Andrei Simion <andrei.simion at microchip.com>
> [Use per-device WDDIS mask and sync MR shadow WDDIS state]
> Signed-off-by: Balakrishnan Sambath <balakrishnan.s at microchip.com>
> ---
> drivers/watchdog/sama5d4_wdt.c | 156 ++++++++++++++++-----------------
> 1 file changed, 77 insertions(+), 79 deletions(-)
>
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index 13e72918338a..b422d0bd75f9 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -24,44 +24,58 @@
> #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;
> u32 ir;
> + u32 wddis_mask;
Introducing this should simply remove the need for 3/3, use this instead
of AT91_WDT_WDDIS everywhere.
> unsigned long last_ping;
> bool need_irq;
> - bool sam9x60_support;
> + bool is_modern_chip;
The previous name was better.
> };
>
> +static inline bool wdt_enabled(struct sama5d4_wdt *wdt, u32 mr)
> +{
> + return !(mr & wdt->wddis_mask);
> +}
> +
This is unrelated to the actual fix. This patch does to much and is
difficult to review and to backport, please separate the actual fix
about wddis and the rest.
> 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 bool check_is_modern_chip_by_compatible(struct device *dev)
> +{
> + if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") ||
> + of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt"))
> + return true;
> +
> + return false;
> +}
> +
> 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);
> @@ -71,322 +85,306 @@ static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
>
> 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)
> +static int wdt_start(struct watchdog_device *wdd)
> {
> struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>
> - if (wdt->sam9x60_support) {
> - writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
> - wdt->mr &= ~AT91_SAM9X60_WDDIS;
> - } else {
> - wdt->mr &= ~AT91_WDT_WDDIS;
> - }
> + if (wdt->is_modern_chip)
> + writel_relaxed(wdt->ir, wdt->reg_base + AT91_WDT_IER);
> + wdt->mr &= ~wdt->wddis_mask;
> wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>
> return 0;
> }
>
> -static int sama5d4_wdt_stop(struct watchdog_device *wdd)
> +static int wdt_stop(struct watchdog_device *wdd)
> {
> struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>
> - if (wdt->sam9x60_support) {
> - writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
> - wdt->mr |= AT91_SAM9X60_WDDIS;
> - } else {
> - wdt->mr |= AT91_WDT_WDDIS;
> - }
> + if (wdt->is_modern_chip)
> + writel_relaxed(wdt->ir, wdt->reg_base + AT91_WDT_IDR);
> + wdt->mr |= wdt->wddis_mask;
> wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>
> return 0;
> }
>
> -static int sama5d4_wdt_ping(struct watchdog_device *wdd)
> +static int 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)
> +static int wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> {
> struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> u32 value = WDT_SEC2TICKS(timeout);
>
> - if (wdt->sam9x60_support) {
> - wdt_write(wdt, AT91_SAM9X60_WLR,
> - AT91_SAM9X60_SET_COUNTER(value));
> + if (wdt->is_modern_chip) {
> + wdt_write(wdt, AT91_WDT_WLR,
> + AT91_WDT_SET_COUNTER(value));
>
> wdd->timeout = timeout;
> return 0;
> }
>
> 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);
> + if (wdt_enabled(wdt, wdt->mr))
> + wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~wdt->wddis_mask);
>
> 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,
> + .start = wdt_start,
> + .stop = wdt_stop,
> + .ping = wdt_ping,
> + .set_timeout = wdt_set_timeout,
> };
>
> -static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
> +static irqreturn_t wdt_irq_handler(int irq, void *dev_id)
> {
> struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
> u32 reg;
>
> - if (wdt->sam9x60_support)
> - reg = wdt_read(wdt, AT91_SAM9X60_ISR);
> + if (wdt->is_modern_chip)
> + reg = wdt_read(wdt, AT91_WDT_ISR);
> else
> reg = wdt_read(wdt, AT91_WDT_SR);
>
> if (reg) {
> 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)
> +static int of_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
> {
> const char *tmp;
>
> - if (wdt->sam9x60_support)
> - wdt->mr = AT91_SAM9X60_WDDIS;
> - else
> - wdt->mr = AT91_WDT_WDDIS;
> + wdt->mr = wdt->wddis_mask;
>
> if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
> !strcmp(tmp, "software"))
> wdt->need_irq = true;
>
> 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)
> +static int wdt_init(struct sama5d4_wdt *wdt)
> {
> + struct watchdog_device *wdd = &wdt->wdd;
> u32 reg, val;
>
> val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
> +
> /*
> * 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 the watchdog is not running, we need to disable it properly.
> + * Otherwise, we can safely update it.
> */
> - if (!wdt_enabled) {
> - reg = wdt_read(wdt, AT91_WDT_MR);
> - if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
> - wdt_write_nosleep(wdt, AT91_WDT_MR,
> - reg | AT91_SAM9X60_WDDIS);
> - else if (!wdt->sam9x60_support &&
> - (!(reg & AT91_WDT_WDDIS)))
> - wdt_write_nosleep(wdt, AT91_WDT_MR,
> - reg | AT91_WDT_WDDIS);
> + reg = wdt_read(wdt, AT91_WDT_MR);
> + if (wdt_enabled(wdt, reg)) {
> + wdt->mr &= ~wdt->wddis_mask;
> + set_bit(WDOG_HW_RUNNING, &wdd->status);
> + } else {
> + wdt->mr |= wdt->wddis_mask;
> }
>
> - if (wdt->sam9x60_support) {
> + if (wdt->is_modern_chip) {
> if (wdt->need_irq)
> - wdt->ir = AT91_SAM9X60_PERINT;
> + wdt->ir = AT91_WDT_PERINT;
> else
> - wdt->mr |= AT91_SAM9X60_PERIODRST;
> + wdt->mr |= AT91_WDT_PERIODRST;
>
> - wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
> - wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val));
> + wdt_write(wdt, AT91_WDT_IER, wdt->ir);
> + wdt_write(wdt, AT91_WDT_WLR, AT91_WDT_SET_COUNTER(val));
> } else {
> wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
> wdt->mr |= AT91_WDT_SET_WDV(val);
>
> if (wdt->need_irq)
> wdt->mr |= AT91_WDT_WDFIEN;
> else
> wdt->mr |= AT91_WDT_WDRSTEN;
> }
>
> wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
>
> return 0;
> }
>
> -static int sama5d4_wdt_probe(struct platform_device *pdev)
> +static int 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 reg;
> 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;
> -
> - if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") ||
> - of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt"))
> - wdt->sam9x60_support = true;
> + wdt->is_modern_chip = check_is_modern_chip_by_compatible(dev);
> + if (wdt->is_modern_chip)
> + wdt->wddis_mask = AT91_WDT_WDDIS_MODERN;
> + else
> + wdt->wddis_mask = AT91_WDT_WDDIS_LEGACY;
>
> watchdog_set_drvdata(wdd, wdt);
>
> regs = devm_platform_ioremap_resource(pdev, 0);
> if (IS_ERR(regs))
> return PTR_ERR(regs);
>
> wdt->reg_base = regs;
>
> - ret = of_sama5d4_wdt_init(dev->of_node, wdt);
> + ret = of_wdt_init(dev->of_node, wdt);
> if (ret)
> return ret;
>
> if (wdt->need_irq) {
> irq = irq_of_parse_and_map(dev->of_node, 0);
> if (!irq) {
> dev_warn(dev, "failed to get IRQ from DT\n");
> wdt->need_irq = false;
> }
> }
>
> if (wdt->need_irq) {
> - ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
> + ret = devm_request_irq(dev, irq, 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);
>
> - reg = wdt_read(wdt, AT91_WDT_MR);
> - if (!(reg & AT91_WDT_WDDIS)) {
> - wdt->mr &= ~AT91_WDT_WDDIS;
> - set_bit(WDOG_HW_RUNNING, &wdd->status);
> - }
> -
> - ret = sama5d4_wdt_init(wdt);
> + ret = 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[] = {
> +static const struct of_device_id wdt_of_match[] = {
> {
> .compatible = "atmel,sama5d4-wdt",
> },
> {
> .compatible = "microchip,sam9x60-wdt",
> },
> {
> .compatible = "microchip,sama7g5-wdt",
> },
>
> { }
> };
> -MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
> +MODULE_DEVICE_TABLE(of, wdt_of_match);
>
> -static int sama5d4_wdt_suspend_late(struct device *dev)
> +static int wdt_suspend_late(struct device *dev)
> {
> struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
>
> if (watchdog_active(&wdt->wdd))
> - sama5d4_wdt_stop(&wdt->wdd);
> + wdt_stop(&wdt->wdd);
>
> return 0;
> }
>
> -static int sama5d4_wdt_resume_early(struct device *dev)
> +static int 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);
> + wdt_init(wdt);
>
> if (watchdog_active(&wdt->wdd))
> - sama5d4_wdt_start(&wdt->wdd);
> + wdt_start(&wdt->wdd);
>
> return 0;
> }
>
> static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
> - LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
> - sama5d4_wdt_resume_early)
> + LATE_SYSTEM_SLEEP_PM_OPS(wdt_suspend_late,
> + wdt_resume_early)
> };
>
> static struct platform_driver sama5d4_wdt_driver = {
> - .probe = sama5d4_wdt_probe,
> + .probe = wdt_probe,
> .driver = {
> .name = "sama5d4_wdt",
> .pm = pm_sleep_ptr(&sama5d4_wdt_pm_ops),
> - .of_match_table = sama5d4_wdt_of_match,
> + .of_match_table = wdt_of_match,
> }
> };
> module_platform_driver(sama5d4_wdt_driver);
>
> MODULE_AUTHOR("Atmel Corporation");
> MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
> MODULE_LICENSE("GPL v2");
> --
> 2.34.1
>
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
More information about the linux-arm-kernel
mailing list