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Date:   Tue, 22 Jan 2019 07:47:50 -0800
From:   Guenter Roeck <linux@roeck-us.net>
To:     Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Cc:     mazziesaccount@gmail.com, lee.jones@linaro.org, robh+dt@kernel.org,
        mark.rutland@arm.com, lgirdwood@gmail.com, broonie@kernel.org,
        gregkh@linuxfoundation.org, rafael@kernel.org,
        mturquette@baylibre.com, sboyd@kernel.org,
        linus.walleij@linaro.org, bgolaszewski@baylibre.com,
        sre@kernel.org, a.zummo@towertech.it,
        alexandre.belloni@bootlin.com, wim@linux-watchdog.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-rtc@vger.kernel.org,
        linux-watchdog@vger.kernel.org, mikko.mutanen@fi.rohmeurope.com,
        heikki.haikola@fi.rohmeurope.com
Subject: Re: [RFC PATCH v1 13/13] watchdog: bd70528: Initial support for ROHM
 BD70528 watchdog block
Message-ID: <20190122154750.GB1705@roeck-us.net>
References: <cover.1548149337.git.matti.vaittinen@fi.rohmeurope.com>
 <ec70833179d1953dbc91e01901b79d3319ff013d.1548149337.git.matti.vaittinen@fi.rohmeurope.com>
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On Tue, Jan 22, 2019 at 11:48:36AM +0200, Matti Vaittinen wrote:
> Initial support for watchdog block included in ROHM BD70528
> power management IC.
> 
> Configurations for low power states are still to be checked.
> 
> Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
> ---
>  drivers/watchdog/Kconfig       |  12 +++
>  drivers/watchdog/Makefile      |   1 +
>  drivers/watchdog/bd70528_wdt.c | 161 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 174 insertions(+)
>  create mode 100644 drivers/watchdog/bd70528_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 57f017d74a97..f30e3a3e886e 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -90,6 +90,18 @@ config SOFT_WATCHDOG_PRETIMEOUT
>  	  watchdog. Be aware that governors might affect the watchdog because it
>  	  is purely software, e.g. the panic governor will stall it!
>  
> +config BD70528_WATCHDOG
> +	tristate "ROHM BD70528 PMIC Watchdog"
> +	depends on MFD_ROHM_BD70528
> +	select WATCHDOG_CORE
> +	help
> +	  Support for the watchdog in the ROHM BD70528 PMIC. Watchdog trigger
> +	  cause system reset.
> +
> +	  Say Y here to include support for the ROHM BD70528 watchdog.
> +	  Alternatively say M to compile the driver as a module,
> +	  which will be called bd70528_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 a0917ef28e07..1ce87a3b1172 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -204,6 +204,7 @@ obj-$(CONFIG_WATCHDOG_SUN4V)		+= sun4v_wdt.o
>  obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>  
>  # Architecture Independent
> +obj-$(CONFIG_BD70528_WATCHDOG) += bd70528_wdt.o
>  obj-$(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/bd70528_wdt.c b/drivers/watchdog/bd70528_wdt.c
> new file mode 100644
> index 000000000000..e9a32566f595
> --- /dev/null
> +++ b/drivers/watchdog/bd70528_wdt.c
> @@ -0,0 +1,161 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2018 ROHM Semiconductors
> +// ROHM BD70528MWV watchdog driver
> +
> +#include <linux/bcd.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/rohm-bd70528.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/watchdog.h>
> +
> +static int bd70528_wdt_set(struct bd70528 *bd70528, int enable)
> +{
> +	int ret;
> +
> +	if (bd70528->rtc_timer_lock)
> +		mutex_lock(bd70528->rtc_timer_lock);

This looks awkward. I don't think the if() is necessary.

> +
> +	ret = bd70528->wdt_set(bd70528, enable, NULL);
> +
> +	if (bd70528->rtc_timer_lock)
> +		mutex_unlock(bd70528->rtc_timer_lock);
> +	return ret;
> +}
> +
> +static int bd70528_wdt_start(struct watchdog_device *wdt)
> +{
> +	struct bd70528 *bd70528 = watchdog_get_drvdata(wdt);
> +
> +	return bd70528_wdt_set(bd70528, 1);
> +}
> +
> +static int bd70528_wdt_stop(struct watchdog_device *wdt)
> +{
> +	struct bd70528 *bd70528 = watchdog_get_drvdata(wdt);
> +
> +	return bd70528_wdt_set(bd70528, 0);
> +}
> +
> +static int bd70528_wdt_set_timeout(struct watchdog_device *wdt,
> +				    unsigned int timeout)
> +{
> +	unsigned int hours;
> +	unsigned int minutes;
> +	unsigned int seconds;
> +	int ret;
> +	struct bd70528 *bd70528 = watchdog_get_drvdata(wdt);
> +
> +	seconds = timeout;
> +	hours = timeout / (60 * 60);
> +	/* Maximum timeout is 1h 59m 59s => hours is 1 or 0 */
> +	if (hours)
> +		seconds -= (60 * 60);
> +	minutes = seconds / 60;
> +	seconds = seconds % 60;
> +
> +	if (bd70528->rtc_timer_lock)
> +		mutex_lock(bd70528->rtc_timer_lock);
> +
> +	ret = bd70528->wdt_set(bd70528, 0, NULL);
> +	if (ret)
> +		goto out_unlock;
> +
> +	ret = regmap_update_bits(bd70528->chip.regmap, BD70528_REG_WDT_HOUR,
> +				 BD70528_MASK_WDT_HOUR, hours);
> +	if (ret) {
> +		dev_err(bd70528->chip.dev, "Failed to set WDT hours\n");
> +		goto out_en_unlock;
> +	}
> +	ret = regmap_update_bits(bd70528->chip.regmap, BD70528_REG_WDT_MINUTE,
> +				 BD70528_MASK_WDT_MINUTE, bin2bcd(minutes));
> +	if (ret) {
> +		dev_err(bd70528->chip.dev, "Failed to set WDT minutes\n");
> +		goto out_en_unlock;
> +	}
> +	ret = regmap_update_bits(bd70528->chip.regmap, BD70528_REG_WDT_SEC,
> +				 BD70528_MASK_WDT_SEC, bin2bcd(seconds));
> +	if (ret) {
> +		dev_err(bd70528->chip.dev, "Failed to set WDT seconds\n");
> +		goto out_en_unlock;

Unnecessary goto.

> +	}
> +
> +out_en_unlock:
> +	ret = bd70528->wdt_set(bd70528, 1, NULL);
> +out_unlock:
> +	if (bd70528->rtc_timer_lock)
> +		mutex_lock(bd70528->rtc_timer_lock);

I don't think this code was ever tested.

> +
> +	return ret;
> +}
> +
> +static const struct watchdog_info bd70528_wdt_info = {
> +	.identity = "bd70528-wdt",
> +	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> +};
> +
> +static const struct watchdog_ops bd70528_wdt_ops = {
> +	.start		= bd70528_wdt_start,
> +	.stop		= bd70528_wdt_stop,
> +	/*
> +	 *  bd70528 WDT ping is same as enable. Eg, writing 'enable' to enabled
> +	 * WDT will restart the timeout
> +	 */
Unnecessary comment.

> +	.ping		= bd70528_wdt_start,
> +	.set_timeout	= bd70528_wdt_set_timeout,
> +};
> +
> +/* Max time we can set is 1 hour, 59 minutes and 59 seconds */
> +#define WDT_MAX_MS ((2 * 60 * 60 - 1) * 1000)
> +/* Minimum time is 1 second */
> +#define WDT_MIN_MS 1000
> +static struct watchdog_device bd70528_wd = {
> +	.info = &bd70528_wdt_info,
> +	.ops =  &bd70528_wdt_ops,
> +	.min_hw_heartbeat_ms = WDT_MIN_MS,
> +	.max_hw_heartbeat_ms = WDT_MAX_MS,
> +};
> +
> +static int bd70528_wdt_probe(struct platform_device *pdev)
> +{
> +	struct bd70528 *tmp;
> +	struct bd70528 *bd70528;
> +	int ret;
> +
> +	tmp = dev_get_drvdata(pdev->dev.parent);
> +	if (!tmp) {
> +		dev_err(&pdev->dev, "No MFD driver data\n");
> +		return -EINVAL;
> +	}
> +	bd70528 = devm_kzalloc(&pdev->dev, sizeof(*bd70528), GFP_KERNEL);
> +	if (!bd70528)
> +		return -ENOMEM;
> +
> +	*bd70528 = *tmp;
> +	bd70528->chip.dev = &pdev->dev;

This is wrong.
You should not copy the parent's driver data but have local driver
data as needed which then points to the parent's driver data if
needed. I assume this is why the mutex is a pointer, but that
just shows that the whole approach is wrong.

> +
> +	/*
> +	 * TODO: Set the initial state and timeout.

Confused. Why don't you just do it ?

> +	 * See whether the low power states require special handling
> +	 */
> +	watchdog_set_drvdata(&bd70528_wd, bd70528);

At least in theory there can be more than one of those devices
in the system, since it is an i2c device. With that in mind, bd70528_wd
should be locally allocated.

Also, bd70528_wd should be fully initialized. For example, the parent
device is not set.

> +	ret = devm_watchdog_register_device(&pdev->dev, &bd70528_wd);
> +	if (ret < 0)
> +		dev_err(&pdev->dev, "watchdog registration failed: %d\n", ret);
> +
> +	return ret;
> +}
> +static struct platform_driver bd70528_wdt = {
> +	.driver = {
> +		.name = "bd70528-wdt"
> +	},
> +	.probe = bd70528_wdt_probe,
> +};
> +
> +module_platform_driver(bd70528_wdt);
> +
> +MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
> +MODULE_DESCRIPTION("BD70528 watchdog driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.14.3
> 
> 
> -- 
> Matti Vaittinen
> ROHM Semiconductors
> 
> ~~~ "I don't think so," said Rene Descartes.  Just then, he vanished ~~~