From: <Balakrishnan.S@microchip.com>
To: <alexandre.belloni@bootlin.com>
Cc: <wim@linux-watchdog.org>, <linux@roeck-us.net>,
<Nicolas.Ferre@microchip.com>, <claudiu.beznea@tuxon.dev>,
<linux-watchdog@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <andrei.simion@microchip.com>
Subject: Re: [PATCH 2/3] watchdog: sama5d4_wdt: Refactor the driver
Date: Mon, 2 Mar 2026 07:24:30 +0000 [thread overview]
Message-ID: <12a176ca-da67-4e26-b37e-5a03defb4c7e@microchip.com> (raw)
In-Reply-To: <2026022708054233bc5648@mail.local>
On 27/02/26 1:35 pm, Alexandre Belloni wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> On 27/02/2026 13:01:15+0530, Balakrishnan Sambath wrote:
>> From: Andrei Simion <andrei.simion@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@microchip.com>
>> [Use per-device WDDIS mask and sync MR shadow WDDIS state]
>> Signed-off-by: Balakrishnan Sambath <balakrishnan.s@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.
Okay, I'll keep this.
>
>> unsigned long last_ping;
>> bool need_irq;
>> - bool sam9x60_support;
>> + bool is_modern_chip;
>
> The previous name was better.
Got it, I'll address this as it seems meaningful to retain Soc level
details too.
>
>> };
>>
>> +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.
My bad, I'll refactor the fix and refactor as separate chunks in v2.
>
>
>> 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
next prev parent reply other threads:[~2026-03-02 7:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-27 7:31 [PATCH 0/3] watchdog: at91/sama5d4: header cleanup and driver refactor Balakrishnan Sambath
2026-02-27 7:31 ` [PATCH 1/3] watchdog: at91sam9_wdt.h: Cleanup the header file Balakrishnan Sambath
2026-02-27 7:52 ` Alexandre Belloni
2026-03-02 7:11 ` Balakrishnan.S
2026-02-27 7:31 ` [PATCH 2/3] watchdog: sama5d4_wdt: Refactor the driver Balakrishnan Sambath
2026-02-27 8:05 ` Alexandre Belloni
2026-03-02 7:24 ` Balakrishnan.S [this message]
2026-02-27 7:31 ` [PATCH 3/3] watchdog: at91sam9_wdt: Rename AT91_WDT_WDDIS to AT91_WDT_WDDIS_LEGACY Balakrishnan Sambath
2026-02-27 7:44 ` [PATCH 0/3] watchdog: at91/sama5d4: header cleanup and driver refactor Guenter Roeck
2026-03-02 7:26 ` Balakrishnan.S
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