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Date: Thu, 5 Jul 2018 11:48:53 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Pascal PAILLET-LME <p.paillet@...com>,
"dmitry.torokhov@...il.com" <dmitry.torokhov@...il.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"lee.jones@...aro.org" <lee.jones@...aro.org>,
"lgirdwood@...il.com" <lgirdwood@...il.com>,
"broonie@...nel.org" <broonie@...nel.org>,
"wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
"benjamin.gaignard@...aro.org" <benjamin.gaignard@...aro.org>
Subject: Re: [PATCH 8/8] watchdog: stpmu1: add stpmu1 watchdog driver
On 07/05/2018 08:14 AM, Pascal PAILLET-LME wrote:
> From: pascal paillet <p.paillet@...com>
>
> The stpmu1 PMIC embeds a watchdog which is disabled by default. As soon
> as the watchdog is started, it must be refreshed periodically otherwise
> the PMIC goes off.
>
> Signed-off-by: pascal paillet <p.paillet@...com>
> ---
> drivers/watchdog/Kconfig | 12 +++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/stpmu1_wdt.c | 177 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 190 insertions(+)
> create mode 100644 drivers/watchdog/stpmu1_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 9af07fd..2155f4d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -796,6 +796,18 @@ config STM32_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called stm32_iwdg.
>
> +config STPMU1_WATCHDOG
> + tristate "STPMU1 PMIC watchdog support"
> + depends on MFD_STPMU1
> + select WATCHDOG_CORE
> + help
> + Say Y here to include watchdog support embedded into STPMU1 PMIC.
> + If the watchdog timer expires, stpmu1 shut-down all its power
> + supplies.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called spmu1_wdt.
> +
> config UNIPHIER_WATCHDOG
> tristate "UniPhier watchdog support"
> depends on ARCH_UNIPHIER || COMPILE_TEST
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 1d3c6b0..c9eba94 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -216,3 +216,4 @@ obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
> obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
> obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
> obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
> +obj-$(CONFIG_STPMU1_WATCHDOG) += stpmu1_wdt.o
> diff --git a/drivers/watchdog/stpmu1_wdt.c b/drivers/watchdog/stpmu1_wdt.c
> new file mode 100644
> index 0000000..57e0afa
> --- /dev/null
> +++ b/drivers/watchdog/stpmu1_wdt.c
> @@ -0,0 +1,177 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
> + * Author: Philippe Peurichard <philippe.peurichard@...com>,
> + * Pascal Paillet <p.paillet@...com> for STMicroelectronics.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/mfd/stpmu1.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +#include <linux/reboot.h>
> +#include <linux/slab.h>
> +#include <linux/watchdog.h>
> +
> +/* WATCHDOG CONTROL REGISTER bit */
> +#define WDT_START BIT(0)
> +#define WDT_PING BIT(1)
> +#define WDT_START_MASK BIT(0)
> +#define WDT_PING_MASK BIT(1)
> +
> +#define PMIC_WDT_MIN_TIMEOUT 1
> +#define PMIC_WDT_MAX_TIMEOUT 256
> +
> +struct stpmu1_wdt {
> + struct stpmu1_dev *pmic;
> + struct watchdog_device wdtdev;
> + struct notifier_block restart_handler;
> +};
> +
> +static int pmic_wdt_start(struct watchdog_device *wdd)
> +{
> + struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + return regmap_update_bits(wdt->pmic->regmap,
> + WCHDG_CR, WDT_START_MASK, WDT_START);
> +}
> +
> +static int pmic_wdt_stop(struct watchdog_device *wdd)
> +{
> + struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + return regmap_update_bits(wdt->pmic->regmap,
> + WCHDG_CR, WDT_START_MASK, ~WDT_START);
> +}
> +
> +static int pmic_wdt_ping(struct watchdog_device *wdd)
> +{
> + struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
> + int ret;
> +
> + return regmap_update_bits(wdt->pmic->regmap,
> + WCHDG_CR, WDT_PING_MASK, WDT_PING);
> + return ret;
> +}
> +
> +static int pmic_wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
> + int ret;
> +
> + ret = regmap_write(wdt->pmic->regmap, WCHDG_TIMER_CR, timeout);
> + if (ret)
> + dev_err(wdt->pmic->dev,
> + "Failed to set watchdog timeout (err = %d)\n", ret);
> + else
> + wdd->timeout = PMIC_WDT_MAX_TIMEOUT;
First the requested timeout is set, then the caller is notified
that the timeout was set to the maximum possible value ? That doesn't
make sense. If that is really intentional, I would expect a detailed
explanation, and I would expect that the value written into the chip
register matches the value reported back to the user.
> +
> + return ret;
> +}
> +
> +static int pmic_wdt_restart_handler(struct notifier_block *this,
> + unsigned long mode, void *cmd)
> +{
> + struct stpmu1_wdt *wdt = container_of(this,
> + struct stpmu1_wdt,
> + restart_handler);
> +
> + dev_info(wdt->pmic->dev,
> + "PMIC Watchdog Elapsed (timeout %d), shutdown of PMIC initiated\n",
> + wdt->wdtdev.timeout);
> +
Register a restart handler just to issue a message ? That is quite pointless.
A restart handler is supposed to restart the system. Besides, the message
is highly misleading; there is no reason to believe that it will be called
after the watchdog expired.
This function should restart the system. If it doesn't, drop it.
> + return NOTIFY_DONE;
> +}
> +
> +static const struct watchdog_info pmic_watchdog_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
> + .identity = "STPMU1 PMIC Watchdog",
> +};
> +
> +static const struct watchdog_ops pmic_watchdog_ops = {
> + .owner = THIS_MODULE,
> + .start = pmic_wdt_start,
> + .stop = pmic_wdt_stop,
> + .ping = pmic_wdt_ping,
> + .set_timeout = pmic_wdt_set_timeout,
> +};
> +
> +static int pmic_wdt_probe(struct platform_device *pdev)
> +{
> + int ret;
> + struct stpmu1_dev *pmic;
> + struct stpmu1_wdt *wdt;
> +
> + if (!pdev->dev.parent)
> + return -EINVAL;
> +
> + pmic = dev_get_drvdata(pdev->dev.parent);
> + if (!pmic)
> + return -EINVAL;
> +
> + wdt = devm_kzalloc(&pdev->dev, sizeof(struct stpmu1_wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
> +
> + wdt->pmic = pmic;
> +
> + wdt->wdtdev.info = &pmic_watchdog_info;
> + wdt->wdtdev.ops = &pmic_watchdog_ops;
> + wdt->wdtdev.min_timeout = PMIC_WDT_MIN_TIMEOUT;
> + wdt->wdtdev.max_timeout = PMIC_WDT_MAX_TIMEOUT;
> + wdt->wdtdev.timeout = PMIC_WDT_MAX_TIMEOUT;
256 seconds default timeout ? Unusual, just making sure that this is what you want.
> +
> + wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
> +
> + watchdog_set_drvdata(&wdt->wdtdev, wdt);
> + dev_set_drvdata(&pdev->dev, wdt);
> +
> + ret = watchdog_register_device(&wdt->wdtdev);
> + if (ret)
> + return ret;
> +
> + wdt->restart_handler.notifier_call = pmic_wdt_restart_handler;
> + wdt->restart_handler.priority = 128;
> + ret = register_restart_handler(&wdt->restart_handler);
Why is the restart handler provided by the watchdog core not sufficient ?
> + if (ret) {
> + dev_err(wdt->pmic->dev, "failed to register restart handler\n");
> + return ret;
> + }
> +
> + dev_dbg(wdt->pmic->dev, "PMIC Watchdog driver probed\n");
The only reasons not to use the devm_ function to register the watchdog
are the restart handler, which 1) doesn't do anything and 2) should use
the watchdog core, and this debug message. I would suggest to use the
devm_ function to register the watchdog instead.
> + return 0;
> +}
> +
> +static int pmic_wdt_remove(struct platform_device *pdev)
> +{
> + struct stpmu1_wdt *wdt = dev_get_drvdata(&pdev->dev);
> +
> + unregister_restart_handler(&wdt->restart_handler);
> + watchdog_unregister_device(&wdt->wdtdev);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id of_pmic_wdt_match[] = {
> + { .compatible = "st,stpmu1-wdt" },
> + { },
> +};
> +
> +MODULE_DEVICE_TABLE(of, of_pmic_wdt_match);
> +
> +static struct platform_driver stpmu1_wdt_driver = {
> + .probe = pmic_wdt_probe,
> + .remove = pmic_wdt_remove,
> + .driver = {
> + .name = "stpmu1-wdt",
> + .of_match_table = of_pmic_wdt_match,
> + },
> +};
> +module_platform_driver(stpmu1_wdt_driver);
> +
> +MODULE_AUTHOR("philippe.peurichard@...com>");
> +MODULE_DESCRIPTION("Watchdog driver for STPMU1 device");
> +MODULE_LICENSE("GPL");
>
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