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SubjectRe: [PATCH 2/2] watchdog: imx_sc: Add pretimeout support
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On 4/24/19 6:14 PM, Anson Huang wrote:
> i.MX system controller watchdog can support pretimeout IRQ
> via general SCU MU IRQ, it depends on IMX_SCU and driver MUST
> be probed after SCU IPC ready, then enable corresponding SCU
> IRQ group and register SCU IRQ notifier, when watchdog pretimeout
> IRQ fires, SCU MU IRQ will be handled and watchdog pretimeout
> notifier will be called to handle the event.
>

Ah, here is the missing patch.

As mentioned in my other reply, the watchdog driver does now depend
on the SCU IPC handle and should be instantiated accordingly.
Using -EPROBE_DEFER to work around bad dependencies is not a solution.

Additional comment below.

Guenter

> Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
> ---
> drivers/watchdog/Kconfig | 1 +
> drivers/watchdog/imx_sc_wdt.c | 65 +++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 61 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 44a3158..f2c2c1a 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -644,6 +644,7 @@ config IMX2_WDT
> config IMX_SC_WDT
> tristate "IMX SC Watchdog"
> depends on HAVE_ARM_SMCCC
> + depends on IMX_SCU
> select WATCHDOG_CORE
> help
> This is the driver for the system controller watchdog
> diff --git a/drivers/watchdog/imx_sc_wdt.c b/drivers/watchdog/imx_sc_wdt.c
> index 49848b6..f45ed10 100644
> --- a/drivers/watchdog/imx_sc_wdt.c
> +++ b/drivers/watchdog/imx_sc_wdt.c
> @@ -4,6 +4,7 @@
> */
>
> #include <linux/arm-smccc.h>
> +#include <linux/firmware/imx/sci.h>
> #include <linux/io.h>
> #include <linux/init.h>
> #include <linux/kernel.h>
> @@ -33,11 +34,16 @@
>
> #define SC_TIMER_WDOG_ACTION_PARTITION 0
>
> +#define SC_IRQ_WDOG 1
> +#define SC_IRQ_GROUP_WDOG 1
> +
> static bool nowayout = WATCHDOG_NOWAYOUT;
> module_param(nowayout, bool, 0000);
> MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>
> +struct watchdog_device *imx_sc_wdd;
> +
> static int imx_sc_wdt_ping(struct watchdog_device *wdog)
> {
> struct arm_smccc_res res;
> @@ -85,12 +91,42 @@ static int imx_sc_wdt_set_timeout(struct watchdog_device *wdog,
> return res.a0 ? -EACCES : 0;
> }
>
> +static int imx_sc_wdt_set_pretimeout(struct watchdog_device *wdog,
> + unsigned int pretimeout)
> +{
> + struct arm_smccc_res res;
> +
> + wdog->pretimeout = pretimeout;
> + arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_PRETIME_WDOG,
> + pretimeout * 1000, 0, 0, 0, 0, 0, &res);
> +
> + return res.a0 ? -EACCES : 0;

If this function returns an error, why does it set wdog->pretimeout
unconditionally ? That seems wrong.

> +}
> +
> +static int imx_sc_wdt_notify(struct notifier_block *nb,
> + unsigned long event, void *group)
> +{
> + /* ignore other irqs */
> + if (!(event & SC_IRQ_WDOG &&
> + (*(u8 *)group == SC_IRQ_GROUP_WDOG)))

if (!(event & SC_IRQ_WDO) || *(u8 *)group != SC_IRQ_GROUP_WDOG)

would be easier to understand. Either case, the second part of the expression
has an unnecessary (), and multi-line alignment seems to be off.

> + return 0;
> +
> + watchdog_notify_pretimeout(imx_sc_wdd);

The notifier block should be embedded in a local data structure,
which would include strict watchdog_device and struct notifier_block.
This would avoid the need for a static variable.

> +
> + return 0;

If the function always returns 0, why not the following ?
Above code seems unnecessary complex for no good reason.

if (event & SC_IRQ_WDOG &&
*(u8 *)group == SC_IRQ_GROUP_WDOG)
watchdog_notify_pretimeout(imx_sc_wdd);

return 0;

> +}
> +
> +static struct notifier_block imx_sc_wdt_notifier = {
> + .notifier_call = imx_sc_wdt_notify,
> +};
> +
> static const struct watchdog_ops imx_sc_wdt_ops = {
> .owner = THIS_MODULE,
> .start = imx_sc_wdt_start,
> .stop = imx_sc_wdt_stop,
> .ping = imx_sc_wdt_ping,
> .set_timeout = imx_sc_wdt_set_timeout,
> + .set_pretimeout = imx_sc_wdt_set_pretimeout,
> };
>
> static const struct watchdog_info imx_sc_wdt_info = {
> @@ -102,9 +138,15 @@ static const struct watchdog_info imx_sc_wdt_info = {
> static int imx_sc_wdt_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> - struct watchdog_device *imx_sc_wdd;
> int ret;
>
> + /* wait until i.MX SCU IPC ready */
> + ret = imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> + SC_IRQ_WDOG,
> + true);
> + if (ret == -EPROBE_DEFER)
> + return ret;
> +

And if the error is anything else it is ignored ?
Also, what happens if the interrupt triggers before imx_sc_wdd is set ?

> imx_sc_wdd = devm_kzalloc(dev, sizeof(*imx_sc_wdd), GFP_KERNEL);
> if (!imx_sc_wdd)
> return -ENOMEM;
> @@ -117,6 +159,7 @@ static int imx_sc_wdt_probe(struct platform_device *pdev)
> imx_sc_wdd->max_timeout = MAX_TIMEOUT;
> imx_sc_wdd->parent = dev;
> imx_sc_wdd->timeout = DEFAULT_TIMEOUT;
> + imx_sc_wdd->pretimeout = 0;

Unnecessary.

>
> watchdog_init_timeout(imx_sc_wdd, 0, dev);
> watchdog_stop_on_reboot(imx_sc_wdd);
> @@ -128,13 +171,26 @@ static int imx_sc_wdt_probe(struct platform_device *pdev)
> return ret;
> }
>
> + ret = imx_scu_irq_register_notifier(&imx_sc_wdt_notifier);
> + if (ret)
> + dev_warn(&pdev->dev,
> + "Failed to register watchdog irq notifier\n");

pretimeout support doesn't work in this case, and any claim to support it
seems inappropriate.

> +
> return 0;
> }
>
> -static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
> +static int imx_sc_wdt_remove(struct platform_device *pdev)
> {
> - struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> + imx_scu_irq_unregister_notifier(&imx_sc_wdt_notifier);
> + imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
> + SC_IRQ_WDOG,
> + false);
>
I would prefer to see devm_add_action() calls.

> + return 0;
> +}
> +
> +static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
> +{
> if (watchdog_active(imx_sc_wdd))
> imx_sc_wdt_stop(imx_sc_wdd);
>
> @@ -143,8 +199,6 @@ static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
>
> static int __maybe_unused imx_sc_wdt_resume(struct device *dev)
> {
> - struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
> -
> if (watchdog_active(imx_sc_wdd))
> imx_sc_wdt_start(imx_sc_wdd);
>
> @@ -162,6 +216,7 @@ MODULE_DEVICE_TABLE(of, imx_sc_wdt_dt_ids);
>
> static struct platform_driver imx_sc_wdt_driver = {
> .probe = imx_sc_wdt_probe,
> + .remove = imx_sc_wdt_remove,
> .driver = {
> .name = "imx-sc-wdt",
> .of_match_table = imx_sc_wdt_dt_ids,
>

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