Re: [PATCH 3/9] watchdog: Add Photonicat PMU watchdog driver

[Guenter Roeck <linux@roeck-us.net>]

On 9/6/24 02:36, Junhao Xie wrote:
> This driver provides access to Photonicat PMU watchdog functionality.
> 
> Signed-off-by: Junhao Xie <bigfoot@classfun.cn>
> ---
>   drivers/watchdog/Kconfig          |  12 +++
>   drivers/watchdog/Makefile         |   1 +
>   drivers/watchdog/photonicat-wdt.c | 124 ++++++++++++++++++++++++++++++
>   3 files changed, 137 insertions(+)
>   create mode 100644 drivers/watchdog/photonicat-wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index bae1d97cce89..4094216a1c09 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -300,6 +300,18 @@ config MENZ069_WATCHDOG
>   	  This driver can also be built as a module. If so the module
>   	  will be called menz069_wdt.
>   
> +config PHOTONICAT_PMU_WDT
> +	tristate "Photonicat PMU Watchdog"
> +	depends on MFD_PHOTONICAT_PMU
> +	select WATCHDOG_CORE
> +	help
> +	  This driver provides access to Photonicat PMU watchdog functionality.
> +
> +	  Say Y here to include support for the Photonicat PMU Watchdog.
> +
> +	  This driver can also be built as a module. If so the module
> +	  will be called photonicat-wdt.
> +
>   config WDAT_WDT
>   	tristate "ACPI Watchdog Action Table (WDAT)"
>   	depends on ACPI
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index b51030f035a6..14375af84039 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -234,6 +234,7 @@ obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
>   obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
>   obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
>   obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_wdt.o
> +obj-$(CONFIG_PHOTONICAT_PMU_WDT) += photonicat-wdt.o
>   obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
>   obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o
>   obj-$(CONFIG_SL28CPLD_WATCHDOG) += sl28cpld_wdt.o
> diff --git a/drivers/watchdog/photonicat-wdt.c b/drivers/watchdog/photonicat-wdt.c
> new file mode 100644
> index 000000000000..1e758fcfb49f
> --- /dev/null
> +++ b/drivers/watchdog/photonicat-wdt.c
> @@ -0,0 +1,124 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2024 Junhao Xie <bigfoot@classfun.cn>
> + */
> +
> +#include <linux/mfd/photonicat-pmu.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +struct pcat_watchdog {
> +	struct device *dev;

I don't see what this is used for.

> +	struct pcat_pmu *pmu;
> +	struct watchdog_device wdd;
> +	u8 timeout;
> +	bool started;
> +};
> +
> +static const struct watchdog_info pcat_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> +	.identity = "Photonicat PMU Watchdog",
> +};
> +
> +static int pcat_wdt_setup(struct pcat_watchdog *data, int timeout)
> +{
> +	int ret;
> +	u8 time = 0;

Unnecessary initialization.

> +	u8 times[3] = { 60, 60, 0 };
> +
> +	time = MIN(255, MAX(0, timeout));
> +
> +	ret = pcat_pmu_write_data(data->pmu, PCAT_CMD_WATCHDOG_TIMEOUT_SET,
> +				  times, sizeof(times));

Where does this actually send the timeout to the chip ?

> +	if (!ret)
> +		data->started = timeout != 0;
> +
> +	return ret;
> +}
> +
> +static int pcat_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct pcat_watchdog *data = watchdog_get_drvdata(wdev);
> +
> +	return pcat_wdt_setup(data, data->timeout);
> +}
> +
> +static int pcat_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct pcat_watchdog *data = watchdog_get_drvdata(wdev);
> +
> +	return pcat_wdt_setup(data, 0);
> +}
> +
> +static int pcat_wdt_ping(struct watchdog_device *wdev)
> +{
> +	struct pcat_watchdog *data = watchdog_get_drvdata(wdev);
> +
> +	return pcat_pmu_send(data->pmu, PCAT_CMD_HEARTBEAT, NULL, 0);
> +}
> +
> +static int pcat_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
> +{
> +	int ret = 0;
> +	struct pcat_watchdog *data = watchdog_get_drvdata(wdev);
> +
> +	data->timeout = val;

This needs to store 'timeout' in wdev. Storing it locally is unnecessary.

> +	if (data->started)
> +		ret = pcat_wdt_setup(data, data->timeout);

This is misleading because it would permit setting the timeout to
0 when the watchdog isn't running, and then when the watchdog is started
it would not really start it. The code should not use a local "started"
variable but call watchdog_active(). It should also not accept "0"
as a valid timeout.

> +
> +	return ret;
> +}
> +
> +static const struct watchdog_ops pcat_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = pcat_wdt_start,
> +	.stop = pcat_wdt_stop,
> +	.ping = pcat_wdt_ping,
> +	.set_timeout = pcat_wdt_set_timeout,
> +};
> +
> +static int pcat_watchdog_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct pcat_watchdog *watchdog;
> +
> +	watchdog = devm_kzalloc(dev, sizeof(*watchdog), GFP_KERNEL);
> +	if (!watchdog)
> +		return -ENOMEM;
> +
> +	watchdog->dev = dev;
> +	watchdog->pmu = dev_get_drvdata(dev->parent);
> +	watchdog->wdd.info = &pcat_wdt_info;
> +	watchdog->wdd.ops = &pcat_wdt_ops;
> +	watchdog->wdd.timeout = 60;
> +	watchdog->wdd.max_timeout = U8_MAX;
> +	watchdog->wdd.min_timeout = 0;

This effectively lets the user ... kind of ... stop the watchdog
by setting the timeout to 0. This is not acceptable.

> +	watchdog->wdd.parent = dev;
> +
> +	watchdog_stop_on_reboot(&watchdog->wdd);
> +	watchdog_set_drvdata(&watchdog->wdd, watchdog);
> +	platform_set_drvdata(pdev, watchdog);
> +
No watchdog_init_timeout() ?

> +	return devm_watchdog_register_device(dev, &watchdog->wdd);
> +}
> +
> +static const struct of_device_id pcat_watchdog_dt_ids[] = {
> +	{ .compatible = "ariaboard,photonicat-pmu-watchdog", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, pcat_watchdog_dt_ids);
> +
> +static struct platform_driver pcat_watchdog_driver = {
> +	.driver = {
> +		.name = "photonicat-watchdog",
> +		.of_match_table = pcat_watchdog_dt_ids,
> +	},
> +	.probe = pcat_watchdog_probe,
> +};
> +module_platform_driver(pcat_watchdog_driver);
> +
> +MODULE_AUTHOR("Junhao Xie <bigfoot@classfun.cn>");
> +MODULE_DESCRIPTION("Photonicat PMU watchdog");
> +MODULE_LICENSE("GPL");