[v3,3/4] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

Add Watchdog support for ROHM BD9576MUF and BD9573MUF PMICs which are
mainly used to power the R-Car series processors. The watchdog is
pinged using a GPIO and enabled using another GPIO. Additionally
watchdog time-out can be configured to HW prior starting the watchdog.
Watchdog timeout can be configured to detect only delayed ping or in
a window mode where also too fast pings are detected.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
---

Changes from v2:
  - Replace bindings hw_margin_ms and rohm,hw-margin-min-ms with
    rohm,hw-timeout-ms

 drivers/watchdog/Kconfig      |  13 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/bd9576_wdt.c | 290 ++++++++++++++++++++++++++++++++++
 3 files changed, 304 insertions(+)
 create mode 100644 drivers/watchdog/bd9576_wdt.c

On Tue, Sep 29, 2020 at 11:17:07AM +0300, Matti Vaittinen wrote:
> Add Watchdog support for ROHM BD9576MUF and BD9573MUF PMICs which are
> mainly used to power the R-Car series processors. The watchdog is
> pinged using a GPIO and enabled using another GPIO. Additionally
> watchdog time-out can be configured to HW prior starting the watchdog.
> Watchdog timeout can be configured to detect only delayed ping or in
> a window mode where also too fast pings are detected.
> 
> Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 
> Changes from v2:
>   - Replace bindings hw_margin_ms and rohm,hw-margin-min-ms with
>     rohm,hw-timeout-ms
> 
>  drivers/watchdog/Kconfig      |  13 ++
>  drivers/watchdog/Makefile     |   1 +
>  drivers/watchdog/bd9576_wdt.c | 290 ++++++++++++++++++++++++++++++++++
>  3 files changed, 304 insertions(+)
>  create mode 100644 drivers/watchdog/bd9576_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index ab7aad5a1e69..d042a517a946 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -172,6 +172,19 @@ config BD70528_WATCHDOG
>  	  Alternatively say M to compile the driver as a module,
>  	  which will be called bd70528_wdt.
>  
> +config BD957XMUF_WATCHDOG
> +	tristate "ROHM BD9576MUF and BD9573MUF PMIC Watchdog"
> +	depends on MFD_ROHM_BD957XMUF
> +	select WATCHDOG_CORE
> +	help
> +	  Support for the watchdog in the ROHM BD9576 and BD9573 PMICs.
> +	  These PMIC ICs contain watchdog block which can be configured
> +	  to toggle reset line if SoC fails to ping watchdog via GPIO.
> +
> +	  Say Y here to include support for the ROHM BD9576 or BD9573
> +	  watchdog. Alternatively say M to compile the driver as a module,
> +	  which will be called bd9576_wdt.
> +
>  config DA9052_WATCHDOG
>  	tristate "Dialog DA9052 Watchdog"
>  	depends on PMIC_DA9052 || COMPILE_TEST
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 97bed1d3d97c..14d75f98e3df 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -208,6 +208,7 @@ obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>  
>  # Architecture Independent
>  obj-$(CONFIG_BD70528_WATCHDOG) += bd70528_wdt.o
> +obj-$(CONFIG_BD957XMUF_WATCHDOG) += bd9576_wdt.o
>  obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
>  obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
>  obj-$(CONFIG_DA9062_WATCHDOG) += da9062_wdt.o
> diff --git a/drivers/watchdog/bd9576_wdt.c b/drivers/watchdog/bd9576_wdt.c
> new file mode 100644
> index 000000000000..afef19ce01be
> --- /dev/null
> +++ b/drivers/watchdog/bd9576_wdt.c
> @@ -0,0 +1,290 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2020 ROHM Semiconductors
> + *
> + * ROHM BD9576MUF and BD9573MUF Watchdog driver
> + */
> +
> +#include <linux/err.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/mfd/rohm-bd957x.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/watchdog.h>
> +
> +static bool nowayout;
> +module_param(nowayout, bool, 0);
> +MODULE_PARM_DESC(nowayout,
> +		"Watchdog cannot be stopped once started (default=\"false\")");
> +
> +#define HW_MARGIN_MIN 2
> +#define HW_MARGIN_MAX 4416
> +#define BD957X_WDT_DEFAULT_MARGIN 4416
> +
> +struct bd9576_wdt_priv {
> +	struct gpio_desc	*gpiod_ping;
> +	struct gpio_desc	*gpiod_en;
> +	struct device		*dev;
> +	struct regmap		*regmap;
> +	bool			always_running;
> +	struct watchdog_device	wdd;
> +};
> +
> +static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)
> +{
> +	gpiod_set_value_cansleep(priv->gpiod_en, 0);
> +}
> +
> +static int bd9576_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	/* Pulse */
> +	gpiod_set_value_cansleep(priv->gpiod_ping, 1);
> +	gpiod_set_value_cansleep(priv->gpiod_ping, 0);
> +
> +	return 0;
> +}
> +
> +static int bd9576_wdt_start(struct watchdog_device *wdd)
> +{
> +	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	gpiod_set_value_cansleep(priv->gpiod_en, 1);
> +
> +	return bd9576_wdt_ping(wdd);
> +}
> +
> +static int bd9576_wdt_stop(struct watchdog_device *wdd)
> +{
> +	struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	if (!priv->always_running)
> +		bd9576_wdt_disable(priv);
> +	else
> +		set_bit(WDOG_HW_RUNNING, &wdd->status);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info bd957x_wdt_ident = {
> +	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
> +			  WDIOF_SETTIMEOUT,
> +	.identity	= "BD957x Watchdog",
> +};
> +
> +static const struct watchdog_ops bd957x_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= bd9576_wdt_start,
> +	.stop		= bd9576_wdt_stop,
> +	.ping		= bd9576_wdt_ping,
> +};
> +
> +/* Unit is hundreds of uS */
> +#define FASTNG_MIN 23
> +
> +static int find_closest_fast(int target, int *sel, int *val)
> +{
> +	int i;
> +	int window = FASTNG_MIN;
> +
> +	for (i = 0; i < 8 && window < target; i++)
> +		window <<= 1;
> +
> +	*val = window;
> +	*sel = i;
> +
> +	if (i == 8)
> +		return -EINVAL;
> +
> +	return 0;
> +
> +}
> +
> +static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)
> +{
> +	int sel;
> +	static const int multipliers[] = {2, 3, 7, 15};
> +
> +	for (sel = 0; sel < ARRAY_SIZE(multipliers) &&
> +	     multipliers[sel] * fast_val < target; sel++)
> +		;
> +
> +	if (sel == ARRAY_SIZE(multipliers))
> +		return -EINVAL;
> +
> +	*slowsel = sel;
> +
> +	return 0;
> +}
> +
> +static int find_closest_slow(int target, int *slow_sel, int *fast_sel)
> +{
> +	static const int multipliers[] = {2, 3, 7, 15};
> +	int i, j;
> +	int val = 0;
> +	int window = FASTNG_MIN;
> +
> +	for (i = 0; i < 8; i++) {
> +		for (j = 0; j < ARRAY_SIZE(multipliers); j++) {
> +			int slow;
> +
> +			slow = window * multipliers[j];
> +			if (slow >= target && (!val || slow < val)) {
> +				val = slow;
> +				*fast_sel = i;
> +				*slow_sel = j;
> +			}
> +		}
> +		window <<= 1;
> +	}
> +	if (!val)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +#define BD957X_WDG_TYPE_WINDOW BIT(5)
> +#define BD957X_WDG_TYPE_SLOW 0
> +#define BD957X_WDG_TYPE_MASK BIT(5)
> +#define BD957X_WDG_NG_RATIO_MASK 0x18
> +#define BD957X_WDG_FASTNG_MASK 0x7
> +
> +static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,
> +			       int hw_margin_min)
> +{
> +	int ret, fastng, slowng, type, reg, mask;
> +	struct device *dev = priv->dev;
> +
> +	/* convert to 100uS */
> +	hw_margin *= 10;
> +	hw_margin_min *= 10;
> +	if (hw_margin_min) {
> +		int min;
> +
> +		type = BD957X_WDG_TYPE_WINDOW;
> +		dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);
> +		ret = find_closest_fast(hw_margin_min, &fastng, &min);
> +		if (ret) {
> +			dev_err(dev, "bad WDT window for fast timeout\n");
> +			return ret;
> +		}
> +
> +		ret = find_closest_slow_by_fast(min, hw_margin, &slowng);
> +		if (ret) {
> +			dev_err(dev, "bad WDT window\n");
> +			return ret;
> +		}
> +
> +	} else {
> +		type = BD957X_WDG_TYPE_SLOW;
> +		dev_dbg(dev, "Setting type SLOW 0x%x\n", type);
> +		ret = find_closest_slow(hw_margin, &slowng, &fastng);
> +		if (ret) {
> +			dev_err(dev, "bad WDT window\n");
> +			return ret;
> +		}
> +	}
> +
> +	slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;
> +	reg = type | slowng | fastng;
> +	mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |
> +	       BD957X_WDG_FASTNG_MASK;
> +	ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,
> +				 mask, reg);
> +
> +	return ret;
> +}
> +
> +static int bd9576_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->parent->of_node;
> +	struct bd9576_wdt_priv *priv;
> +	u32 hw_margin[2];
> +	u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;
> +	int ret;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	priv->dev = dev;
> +	priv->regmap = dev_get_regmap(dev->parent, NULL);
> +	if (!priv->regmap) {
> +		dev_err(dev, "No regmap found\n");
> +		return -ENODEV;
> +	}
> +
> +	priv->gpiod_en = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
> +						     "rohm,watchdog-enable-gpios",
> +						     0, GPIOD_OUT_LOW,
> +						     "watchdog-enable");
> +	if (IS_ERR(priv->gpiod_en))
> +		return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),
> +			      "getting watchdog-enable GPIO failed\n");
> +
> +	priv->gpiod_ping = devm_gpiod_get_from_of_node(dev, dev->parent->of_node,
> +						     "rohm,watchdog-ping-gpios",
> +						     0, GPIOD_OUT_LOW,
> +						     "watchdog-ping");
> +	if (IS_ERR(priv->gpiod_ping))
> +		return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),
> +				     "getting watchdog-ping GPIO failed\n");
> +
> +	ret = of_property_read_variable_u32_array(np, "rohm,hw-timeout-ms",
> +						  &hw_margin[0], 1, 2);
> +	if (ret < 0 && ret != -EINVAL)
> +		return ret;
> +
> +	if (ret == 1)
> +		hw_margin_max = hw_margin[0];
> +
> +	if (ret == 2) {
> +		hw_margin_max = hw_margin[1];
> +		hw_margin_min = hw_margin[0];
> +	}
> +
> +	ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);
> +	if (ret)
> +		return ret;
> +
> +	priv->always_running = of_property_read_bool(np, "always-running");
> +
> +	watchdog_set_drvdata(&priv->wdd, priv);
> +
> +	priv->wdd.info			= &bd957x_wdt_ident;
> +	priv->wdd.ops			= &bd957x_wdt_ops;
> +	priv->wdd.min_hw_heartbeat_ms	= hw_margin_min;
> +	priv->wdd.max_hw_heartbeat_ms	= hw_margin_max;
> +	priv->wdd.parent		= dev;
> +	priv->wdd.timeout		= (hw_margin_max / 2) * 1000;
> +
> +	watchdog_init_timeout(&priv->wdd, 0, dev);
> +	watchdog_set_nowayout(&priv->wdd, nowayout);
> +
> +	watchdog_stop_on_reboot(&priv->wdd);
> +
> +	if (priv->always_running)
> +		bd9576_wdt_start(&priv->wdd);
> +
> +	return devm_watchdog_register_device(dev, &priv->wdd);
> +}
> +
> +static struct platform_driver bd9576_wdt_driver = {
> +	.driver	= {
> +		.name = "bd9576-wdt",
> +	},
> +	.probe	= bd9576_wdt_probe,
> +};
> +
> +module_platform_driver(bd9576_wdt_driver);
> +
> +MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
> +MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:bd9576-wdt");
> -- 
> 2.21.0
> 
> 
> -- 
> Matti Vaittinen, Linux device drivers
> ROHM Semiconductors, Finland SWDC
> Kiviharjunlenkki 1E
> 90220 OULU
> FINLAND
> 
> ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
> Simon says - in Latin please.
> ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
> Thanks to Simon Glass for the translation =]