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Date: Fri, 30 Aug 2019 09:55:20 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc: wim@...ux-watchdog.org, linux-watchdog@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] watchdog: orion_wdt: use timer1 as a pretimeout
On Fri, Aug 30, 2019 at 09:52:24AM +1200, Chris Packham wrote:
> The orion watchdog can either reset the CPU or generate an interrupt.
> The interrupt would be useful for debugging as it provides panic()
> output about the watchdog expiry, however if the interrupt is used the
> watchdog can't reset the CPU in the event of being stuck in a loop with
> interrupts disabled or if the CPU is prevented from accessing memory
> (e.g. an unterminated DMA).
>
> The Armada SoCs have spare timers that aren't currently used by the
> Linux kernel. We can use timer1 to provide a pre-timeout ahead of the
> watchdog timer and provide the possibility of gathering debug before the
> reset triggers.
>
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> ---
> Changes in v6:
> - Fix bitwise operation in armada375_stop()
> - Add comment about 2nd interrupt being optional
> Changes in v5:
> - Group bit values with register addresses
> - Address review comments from Gunter
> Changes in v3:
> - rebase against linux/master
> Changes in v2:
> - apply changes to armada-38x only
>
> drivers/watchdog/orion_wdt.c | 66 +++++++++++++++++++++++++++++-------
> 1 file changed, 53 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/watchdog/orion_wdt.c b/drivers/watchdog/orion_wdt.c
> index cdb0d174c5e2..1cccf8eb1c5d 100644
> --- a/drivers/watchdog/orion_wdt.c
> +++ b/drivers/watchdog/orion_wdt.c
> @@ -35,7 +35,15 @@
> * Watchdog timer block registers.
> */
> #define TIMER_CTRL 0x0000
> -#define TIMER_A370_STATUS 0x04
> +#define TIMER1_FIXED_ENABLE_BIT BIT(12)
> +#define WDT_AXP_FIXED_ENABLE_BIT BIT(10)
> +#define TIMER1_ENABLE_BIT BIT(2)
> +
> +#define TIMER_A370_STATUS 0x0004
> +#define WDT_A370_EXPIRED BIT(31)
> +#define TIMER1_STATUS_BIT BIT(8)
> +
> +#define TIMER1_VAL_OFF 0x001c
>
> #define WDT_MAX_CYCLE_COUNT 0xffffffff
>
> @@ -43,9 +51,6 @@
> #define WDT_A370_RATIO_SHIFT 5
> #define WDT_A370_RATIO (1 << WDT_A370_RATIO_SHIFT)
>
> -#define WDT_AXP_FIXED_ENABLE_BIT BIT(10)
> -#define WDT_A370_EXPIRED BIT(31)
> -
> static bool nowayout = WATCHDOG_NOWAYOUT;
> static int heartbeat = -1; /* module parameter (seconds) */
>
> @@ -158,6 +163,7 @@ static int armadaxp_wdt_clock_init(struct platform_device *pdev,
> struct orion_watchdog *dev)
> {
> int ret;
> + u32 val;
>
> dev->clk = of_clk_get_by_name(pdev->dev.of_node, "fixed");
> if (IS_ERR(dev->clk))
> @@ -168,10 +174,9 @@ static int armadaxp_wdt_clock_init(struct platform_device *pdev,
> return ret;
> }
>
> - /* Enable the fixed watchdog clock input */
> - atomic_io_modify(dev->reg + TIMER_CTRL,
> - WDT_AXP_FIXED_ENABLE_BIT,
> - WDT_AXP_FIXED_ENABLE_BIT);
> + /* Fix the wdt and timer1 clock freqency to 25MHz */
> + val = WDT_AXP_FIXED_ENABLE_BIT | TIMER1_FIXED_ENABLE_BIT;
> + atomic_io_modify(dev->reg + TIMER_CTRL, val, val);
>
> dev->clk_rate = clk_get_rate(dev->clk);
> return 0;
> @@ -183,6 +188,10 @@ static int orion_wdt_ping(struct watchdog_device *wdt_dev)
> /* Reload watchdog duration */
> writel(dev->clk_rate * wdt_dev->timeout,
> dev->reg + dev->data->wdt_counter_offset);
> + if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
> + writel(dev->clk_rate * (wdt_dev->timeout - wdt_dev->pretimeout),
> + dev->reg + TIMER1_VAL_OFF);
> +
> return 0;
> }
>
> @@ -194,13 +203,18 @@ static int armada375_start(struct watchdog_device *wdt_dev)
> /* Set watchdog duration */
> writel(dev->clk_rate * wdt_dev->timeout,
> dev->reg + dev->data->wdt_counter_offset);
> + if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
> + writel(dev->clk_rate * (wdt_dev->timeout - wdt_dev->pretimeout),
> + dev->reg + TIMER1_VAL_OFF);
>
> /* Clear the watchdog expiration bit */
> atomic_io_modify(dev->reg + TIMER_A370_STATUS, WDT_A370_EXPIRED, 0);
>
> /* Enable watchdog timer */
> - atomic_io_modify(dev->reg + TIMER_CTRL, dev->data->wdt_enable_bit,
> - dev->data->wdt_enable_bit);
> + reg = dev->data->wdt_enable_bit;
> + if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
> + reg |= TIMER1_ENABLE_BIT;
> + atomic_io_modify(dev->reg + TIMER_CTRL, reg, reg);
>
> /* Enable reset on watchdog */
> reg = readl(dev->rstout);
> @@ -277,7 +291,7 @@ static int orion_stop(struct watchdog_device *wdt_dev)
> static int armada375_stop(struct watchdog_device *wdt_dev)
> {
> struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
> - u32 reg;
> + u32 reg, mask;
>
> /* Disable reset on watchdog */
> atomic_io_modify(dev->rstout_mask, dev->data->rstout_mask_bit,
> @@ -287,7 +301,10 @@ static int armada375_stop(struct watchdog_device *wdt_dev)
> writel(reg, dev->rstout);
>
> /* Disable watchdog timer */
> - atomic_io_modify(dev->reg + TIMER_CTRL, dev->data->wdt_enable_bit, 0);
> + mask = dev->data->wdt_enable_bit;
> + if (wdt_dev->info->options & WDIOF_PRETIMEOUT)
> + mask |= TIMER1_ENABLE_BIT;
> + atomic_io_modify(dev->reg + TIMER_CTRL, mask, 0);
>
> return 0;
> }
> @@ -349,7 +366,7 @@ static unsigned int orion_wdt_get_timeleft(struct watchdog_device *wdt_dev)
> return readl(dev->reg + dev->data->wdt_counter_offset) / dev->clk_rate;
> }
>
> -static const struct watchdog_info orion_wdt_info = {
> +static struct watchdog_info orion_wdt_info = {
> .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> .identity = "Orion Watchdog",
> };
> @@ -368,6 +385,16 @@ static irqreturn_t orion_wdt_irq(int irq, void *devid)
> return IRQ_HANDLED;
> }
>
> +static irqreturn_t orion_wdt_pre_irq(int irq, void *devid)
> +{
> + struct orion_watchdog *dev = devid;
> +
> + atomic_io_modify(dev->reg + TIMER_A370_STATUS,
> + TIMER1_STATUS_BIT, 0);
> + watchdog_notify_pretimeout(&dev->wdt);
> + return IRQ_HANDLED;
> +}
> +
> /*
> * The original devicetree binding for this driver specified only
> * one memory resource, so in order to keep DT backwards compatibility
> @@ -589,6 +616,19 @@ static int orion_wdt_probe(struct platform_device *pdev)
> }
> }
>
> + /* Optional 2nd interrupt for pretimeout */
> + irq = platform_get_irq(pdev, 1);
> + if (irq > 0) {
> + orion_wdt_info.options |= WDIOF_PRETIMEOUT;
> + ret = devm_request_irq(&pdev->dev, irq, orion_wdt_pre_irq,
> + 0, pdev->name, dev);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to request IRQ\n");
> + goto disable_clk;
> + }
> + }
> +
> +
> watchdog_set_nowayout(&dev->wdt, nowayout);
> ret = watchdog_register_device(&dev->wdt);
> if (ret)
> --
> 2.23.0
>
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