[v1,4/6] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

Commit Message

Vaittinen, Matti Sept. 17, 2020, 8:03 a.m. UTC

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 <[e-mail]>
---
 drivers/watchdog/Kconfig      |  13 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/bd9576_wdt.c | 295 ++++++++++++++++++++++++++++++++++
 3 files changed, 309 insertions(+)
 create mode 100644 drivers/watchdog/bd9576_wdt.c

Comments

Guenter Roeck Sept. 18, 2020, 5:45 a.m. UTC | #1

On 9/17/20 1:03 AM, 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 <[e-mail]>
> ---
>  drivers/watchdog/Kconfig      |  13 ++
>  drivers/watchdog/Makefile     |   1 +
>  drivers/watchdog/bd9576_wdt.c | 295 ++++++++++++++++++++++++++++++++++
>  3 files changed, 309 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..917c8c7ddeb1
> --- /dev/null
> +++ b/drivers/watchdog/bd9576_wdt.c
> @@ -0,0 +1,295 @@
> +// 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/delay.h>

Alphabetic include file order please.

> +#include <linux/mfd/rohm-bd957x.h>
> +#include <linux/module.h>
> +#include <linux/gpio/consumer.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, hw_margin_min;
> +	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)) {

devm_gpiod_get_from_of_node() can return -EPROBE_DEFER in which case we don't want to see
an error message. I would suggest to use dev_err_probe().

> +		dev_err(dev, "getting watchdog-enable GPIO failed\n");
> +		return PTR_ERR(priv->gpiod_en);
> +	}
> +
> +	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)) {
> +		dev_err(dev, "getting watchdog-ping GPIO failed\n");
> +		return PTR_ERR(priv->gpiod_ping);
> +	}

Same as above.

> +
> +	ret = of_property_read_u32(np,
> +				   "hw_margin_ms", &hw_margin);

Line splits are arbitrary. Why is this "hw_margin_ms" and not "rohm,hw_margin_ms" ?

> +	if (ret) {
> +		if (ret != -EINVAL)
> +			return ret;
> +
> +		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
> +	}
> +
> +	ret = of_property_read_u32(np, "rohm,hw-margin-min-ms", &hw_margin_min);
> +	if (ret == -EINVAL)
> +		hw_margin_min = 0;
> +	else if (ret)
> +		return ret;

Please use a single mechanism to handle -EINVAL after of_property_read_u32().

> +
> +	ret = bd957x_set_wdt_mode(priv, hw_margin, hw_margin_min);
> +	if (ret)
> +		return ret;
> +
> +	priv->always_running = of_property_read_bool(np,
> +						     "always-running");

Another arbitrary line split.

> +
> +	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;
> +	priv->wdd.parent		= dev;
> +	priv->wdd.timeout		= (hw_margin / 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 <[e-mail]>");
> +MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:bd9576-wdt");
>

Vaittinen, Matti Sept. 18, 2020, 6:06 a.m. UTC | #2

Thanks (again) for review Guenter!

On Thu, 2020-09-17 at 22:45 -0700, Guenter Roeck wrote:
> On 9/17/20 1:03 AM, 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 <[e-mail]>
> > ---
> >  drivers/watchdog/Kconfig      |  13 ++
> >  drivers/watchdog/Makefile     |   1 +
> >  drivers/watchdog/bd9576_wdt.c | 295
> > ++++++++++++++++++++++++++++++++++
> >  3 files changed, 309 insertions(+)
> >  create mode 100644 drivers/watchdog/bd9576_wdt.c

> 
> > +
> > +	ret = of_property_read_u32(np,
> > +				   "hw_margin_ms", &hw_margin);
> 
> Line splits are arbitrary. Why is this "hw_margin_ms" and not
> "rohm,hw_margin_ms" ?

"hw_margin_ms" is an existing binding for specifying the maximum TMO in
HW (if I understood it correctly). (It is used at least by the generig
GPIO watchdog) I thought it's better to not invent a new vendor
specific binding when we have a generic one.

https://elixir.bootlin.com/linux/v5.9-rc2/source/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt

> 
> > +	if (ret) {
> > +		if (ret != -EINVAL)
> > +			return ret;
> > +
> > +		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
> > +	}
> > +
> > +	ret = of_property_read_u32(np, "rohm,hw-margin-min-ms",
> > &hw_margin_min);
> > +	if (ret == -EINVAL)
> > +		hw_margin_min = 0;
> > +	else if (ret)
> > +		return ret;
> 
> Please use a single mechanism to handle -EINVAL after
> of_property_read_u32().

Sorry Guenter - I am probably a bit slow today but I am unsure if I
understand the suggestion. Do you mean something like:

hw_margin_min = 0;

ret = of_property_read_u32(np, "rohm,hw-margin-min-ms",
&hw_margin_min);
if (ret && ret != -EINVAL)
	return ret;

Other than that - all findings are clear to me. I'll craft a new
version but I'll wait for a while to see if Lee has time to send some
feedback on MFD so I could get both WDG and MFD fixes to same version
:)

Best Regards
	--Matti


--
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 for the translation Simon)

Guenter Roeck Sept. 19, 2020, 1:49 a.m. UTC | #3

On 9/17/20 11:06 PM, Vaittinen, Matti wrote:
> Thanks (again) for review Guenter!
> 
> On Thu, 2020-09-17 at 22:45 -0700, Guenter Roeck wrote:
>> On 9/17/20 1:03 AM, 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 <[e-mail]>
>>> ---
>>>  drivers/watchdog/Kconfig      |  13 ++
>>>  drivers/watchdog/Makefile     |   1 +
>>>  drivers/watchdog/bd9576_wdt.c | 295
>>> ++++++++++++++++++++++++++++++++++
>>>  3 files changed, 309 insertions(+)
>>>  create mode 100644 drivers/watchdog/bd9576_wdt.c
> 
>>
>>> +
>>> +	ret = of_property_read_u32(np,
>>> +				   "hw_margin_ms", &hw_margin);
>>
>> Line splits are arbitrary. Why is this "hw_margin_ms" and not
>> "rohm,hw_margin_ms" ?
> 
> "hw_margin_ms" is an existing binding for specifying the maximum TMO in
> HW (if I understood it correctly). (It is used at least by the generig
> GPIO watchdog) I thought it's better to not invent a new vendor
> specific binding when we have a generic one.
> 
> https://elixir.bootlin.com/linux/v5.9-rc2/source/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> 
>>
>>> +	if (ret) {
>>> +		if (ret != -EINVAL)
>>> +			return ret;
>>> +
>>> +		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
>>> +	}
>>> +
>>> +	ret = of_property_read_u32(np, "rohm,hw-margin-min-ms",
>>> &hw_margin_min);
>>> +	if (ret == -EINVAL)
>>> +		hw_margin_min = 0;
>>> +	else if (ret)
>>> +		return ret;
>>
>> Please use a single mechanism to handle -EINVAL after
>> of_property_read_u32().
> 
> Sorry Guenter - I am probably a bit slow today but I am unsure if I
> understand the suggestion. Do you mean something like:
> 

    if (ret) {
>>> +		if (ret != -EINVAL)
>>> +			return ret;
>>> +
>>> +		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
>>> +	}

vs.

>>> +	if (ret == -EINVAL)
>>> +		hw_margin_min = 0;
>>> +	else if (ret)
>>> +		return ret;

is not very consistent to me.

Guenter

> hw_margin_min = 0;
> 
> ret = of_property_read_u32(np, "rohm,hw-margin-min-ms",
> &hw_margin_min);
> if (ret && ret != -EINVAL)
> 	return ret;
> 
> Other than that - all findings are clear to me. I'll craft a new
> version but I'll wait for a while to see if Lee has time to send some
> feedback on MFD so I could get both WDG and MFD fixes to same version
> :)
> 
> Best Regards
> 	--Matti
> 
> 
> --
> 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 for the translation Simon)
>

Patch

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..917c8c7ddeb1
--- /dev/null
+++ b/drivers/watchdog/bd9576_wdt.c
@@ -0,0 +1,295 @@ 
+// 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/delay.h>
+#include <linux/mfd/rohm-bd957x.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.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, hw_margin_min;
+	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)) {
+		dev_err(dev, "getting watchdog-enable GPIO failed\n");
+		return PTR_ERR(priv->gpiod_en);
+	}
+
+	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)) {
+		dev_err(dev, "getting watchdog-ping GPIO failed\n");
+		return PTR_ERR(priv->gpiod_ping);
+	}
+
+	ret = of_property_read_u32(np,
+				   "hw_margin_ms", &hw_margin);
+	if (ret) {
+		if (ret != -EINVAL)
+			return ret;
+
+		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
+	}
+
+	ret = of_property_read_u32(np, "rohm,hw-margin-min-ms", &hw_margin_min);
+	if (ret == -EINVAL)
+		hw_margin_min = 0;
+	else if (ret)
+		return ret;
+
+	ret = bd957x_set_wdt_mode(priv, hw_margin, 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;
+	priv->wdd.parent		= dev;
+	priv->wdd.timeout		= (hw_margin / 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 <[e-mail]>");
+MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:bd9576-wdt");