Re: [PATCH v3 07/16] watchdog: add support for sl28cpld watchdog

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 4/23/20 10:45 AM, Michael Walle wrote:
> This adds support for the watchdog of the sl28cpld board management
> controller. This is part of a multi-function device driver.
> 
> Signed-off-by: Michael Walle <michael@xxxxxxxx>

Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
>  drivers/watchdog/Kconfig        |  11 ++
>  drivers/watchdog/Makefile       |   1 +
>  drivers/watchdog/sl28cpld_wdt.c | 233 ++++++++++++++++++++++++++++++++
>  3 files changed, 245 insertions(+)
>  create mode 100644 drivers/watchdog/sl28cpld_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 0663c604bd64..6c53c1d0f348 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -340,6 +340,17 @@ config MLX_WDT
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called mlx-wdt.
>  
> +config SL28CPLD_WATCHDOG
> +	tristate "Kontron sl28 watchdog"
> +	depends on MFD_SL28CPLD
> +	select WATCHDOG_CORE
> +	help
> +	  Say Y here to include support for the watchdog timer
> +	  on the Kontron sl28 CPLD.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called sl28cpld_wdt.
> +
>  # ALPHA Architecture
>  
>  # ARM Architecture
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 6de2e4ceef19..b9ecdf2d7347 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -224,3 +224,4 @@ obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
>  obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_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/sl28cpld_wdt.c b/drivers/watchdog/sl28cpld_wdt.c
> new file mode 100644
> index 000000000000..2640084ace5c
> --- /dev/null
> +++ b/drivers/watchdog/sl28cpld_wdt.c
> @@ -0,0 +1,233 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * sl28cpld watchdog driver.
> + *
> + * Copyright 2019 Kontron Europe GmbH
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/watchdog.h>
> +
> +/*
> + * Watchdog timer block registers.
> + */
> +#define WDT_CTRL			0x00
> +#define  WDT_CTRL_EN			BIT(0)
> +#define  WDT_CTRL_LOCK			BIT(2)
> +#define  WDT_CTRL_ASSERT_SYS_RESET	BIT(6)
> +#define  WDT_CTRL_ASSERT_WDT_TIMEOUT	BIT(7)
> +#define WDT_TIMEOUT			0x01
> +#define WDT_KICK			0x02
> +#define  WDT_KICK_VALUE			0x6b
> +#define WDT_COUNT			0x03
> +
> +#define WDT_DEFAULT_TIMEOUT		10
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +static int timeout;
> +module_param(timeout, int, 0);
> +MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
> +
> +struct sl28cpld_wdt {
> +	struct watchdog_device wdd;
> +	struct regmap *regmap;
> +	u32 offset;
> +	bool assert_wdt_timeout;
> +};
> +
> +static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> +	return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
> +			    WDT_KICK_VALUE);
> +}
> +
> +static int sl28cpld_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
> +	unsigned int val;
> +
> +	val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
> +	if (wdt->assert_wdt_timeout)
> +		val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
> +	if (nowayout)
> +		val |= WDT_CTRL_LOCK;
> +
> +	return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
> +				  val, val);
> +}
> +
> +static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> +	return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
> +				  WDT_CTRL_EN, 0);
> +}
> +
> +static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
> +{
> +	struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
> +
> +	return (ret < 0) ? 0 : val;
> +}
> +
> +static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
> +				    unsigned int timeout)
> +{
> +	struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
> +	int ret;
> +
> +	ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
> +	if (!ret)
> +		wdd->timeout = timeout;
> +
> +	return ret;
> +}
> +
> +static const struct watchdog_info sl28cpld_wdt_info = {
> +	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
> +	.identity = "sl28cpld watchdog",
> +};
> +
> +static struct watchdog_ops sl28cpld_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = sl28cpld_wdt_start,
> +	.stop = sl28cpld_wdt_stop,
> +	.ping = sl28cpld_wdt_ping,
> +	.set_timeout = sl28cpld_wdt_set_timeout,
> +	.get_timeleft = sl28cpld_wdt_get_timeleft,
> +};
> +
> +static int sl28cpld_wdt_probe(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdd;
> +	struct sl28cpld_wdt *wdt;
> +	struct resource *res;
> +	unsigned int status;
> +	unsigned int val;
> +	int ret;
> +
> +	if (!pdev->dev.parent)
> +		return -ENODEV;
> +
> +	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> +	if (!wdt)
> +		return -ENOMEM;
> +
> +	wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!wdt->regmap)
> +		return -ENODEV;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_REG, 0);
> +	if (!res)
> +		return -EINVAL;
> +	wdt->offset = res->start;
> +
> +	wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
> +							    "kontron,assert-wdt-timeout-pin");
> +
> +	/* initialize struct watchdog_device */
> +	wdd = &wdt->wdd;
> +	wdd->parent = &pdev->dev;
> +	wdd->info = &sl28cpld_wdt_info;
> +	wdd->ops = &sl28cpld_wdt_ops;
> +	wdd->min_timeout = 1;
> +	wdd->max_timeout = 255;
> +
> +	watchdog_set_drvdata(wdd, wdt);
> +	watchdog_stop_on_reboot(wdd);
> +
> +	/*
> +	 * Read the status early, in case of an error, we haven't modified the
> +	 * hardware.
> +	 */
> +	ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * Initial timeout value, may be overwritten by device tree or module
> +	 * parmeter in watchdog_init_timeout().
> +	 *
> +	 * Reading a zero here means that either the hardware has a default
> +	 * value of zero (which is very unlikely and definitely a hardware
> +	 * bug) or the bootloader set it to zero. In any case, we handle
> +	 * this case gracefully and set out own timeout.
> +	 */
> +	ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (val)
> +		wdd->timeout = val;
> +	else
> +		wdd->timeout = WDT_DEFAULT_TIMEOUT;
> +
> +	watchdog_init_timeout(wdd, timeout, &pdev->dev);
> +	sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
> +
> +	/* if the watchdog is locked, we set nowayout */
> +	if (status & WDT_CTRL_LOCK)
> +		nowayout = true;
> +	watchdog_set_nowayout(wdd, nowayout);
> +
> +	/*
> +	 * If watchdog is already running, keep it enabled, but make
> +	 * sure its mode is set correctly.
> +	 */
> +	if (status & WDT_CTRL_EN) {
> +		sl28cpld_wdt_start(wdd);
> +		set_bit(WDOG_HW_RUNNING, &wdd->status);
> +	}
> +
> +	ret = devm_watchdog_register_device(&pdev->dev, wdd);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to register watchdog device\n");
> +		return ret;
> +	}
> +
> +	dev_info(&pdev->dev, "initial timeout %d sec%s\n",
> +		 wdd->timeout, nowayout ? ", nowayout" : "");
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id sl28cpld_wdt_of_match[] = {
> +	{ .compatible = "kontron,sl28cpld-wdt" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
> +
> +static const struct platform_device_id sl28cpld_wdt_id_table[] = {
> +	{ "sl28cpld-wdt" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(platform, sl28cpld_wdt_id_table);
> +
> +static struct platform_driver sl28cpld_wdt_driver = {
> +	.probe = sl28cpld_wdt_probe,
> +	.id_table = sl28cpld_wdt_id_table,
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.of_match_table = sl28cpld_wdt_of_match,
> +	},
> +};
> +module_platform_driver(sl28cpld_wdt_driver);
> +
> +MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
> +MODULE_AUTHOR("Michael Walle <michael@xxxxxxxx>");
> +MODULE_LICENSE("GPL");
>