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Message-ID: <c1594be0-5210-bfe0-59b8-d8b163195da5@roeck-us.net>
Date: Fri, 7 Sep 2018 06:48:02 -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>,
"eballetbo@...il.com" <eballetbo@...il.com>
Subject: Re: [PATCH V2 8/8] watchdog: stpmic1: add stpmic1 watchdog driver
On 09/07/2018 05:59 AM, Pascal PAILLET-LME wrote:
> From: pascal paillet <p.paillet@...com>
>
> The stpmic1 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>
> ---
> changes in v2:
> * the hardware component has been renamed from stpmu1 to stpmic1 !
> * change headers
> * handle remarks from Guenter
Hmm ... as if I would remember what those were.
> * fix set timeout
>
> drivers/watchdog/Kconfig | 12 ++++
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/stpmic1_wdt.c | 130 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 143 insertions(+)
> create mode 100644 drivers/watchdog/stpmic1_wdt.c
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 9af07fd..11c5937 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 STPMIC1_WATCHDOG
> + tristate "STPMIC1 PMIC watchdog support"
> + depends on MFD_STPMIC1
> + select WATCHDOG_CORE
> + help
> + Say Y here to include watchdog support embedded into STPMIC1 PMIC.
> + If the watchdog timer expires, stpmic1 shut-down all its power
> + supplies.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called spmic1_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..a898d8f 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_STPMIC1_WATCHDOG) += stpmic1_wdt.o
> diff --git a/drivers/watchdog/stpmic1_wdt.c b/drivers/watchdog/stpmic1_wdt.c
> new file mode 100644
> index 0000000..391e544
> --- /dev/null
> +++ b/drivers/watchdog/stpmic1_wdt.c
> @@ -0,0 +1,130 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) STMicroelectronics 2018
> +// Author: Pascal Paillet <p.paillet@...com> for STMicroelectronics.
> + > +#include <linux/kernel.h>
> +#include <linux/mfd/stpmic1.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 stpmic1_wdt {
> + struct stpmic1_dev *pmic;
> + struct watchdog_device wdtdev;
> +};
> +
> +static int pmic_wdt_start(struct watchdog_device *wdd)
> +{
> + struct stpmic1_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 stpmic1_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 stpmic1_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + return regmap_update_bits(wdt->pmic->regmap,
> + WCHDG_CR, WDT_PING_MASK, WDT_PING);
> +}
> +
> +static int pmic_wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + struct stpmic1_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + return regmap_write(wdt->pmic->regmap, WCHDG_TIMER_CR, timeout - 1);
What happens if the configured timeout is 1 ? Does that translate to a 1-second
timeout ?
This function also has to set wdd->timeout.
> +}
> +
> +static const struct watchdog_info pmic_watchdog_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
No WDIOF_MAGICCLOSE ?
> + .identity = "STPMIC1 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 stpmic1_dev *pmic;
> + struct stpmic1_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 stpmic1_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_MIN_TIMEOUT;
Are you sure about that ? A timeout of 1 second may be a cause for unexpected
reboots if user space is busy. Personally I find it better to set a larger
default and let userspace configure a tighter value if so desired.
Also,
watchdog_init_timeout(&wdt->wdtdev, 0, &pdev->dev);
might be desirable if you want to be able to specify the timeout in the
devicetree file.
> +
> + wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
> +
> + watchdog_set_drvdata(&wdt->wdtdev, wdt);
> + dev_set_drvdata(&pdev->dev, wdt);
Unless I am missing something this should not be needed.
> +
> + ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdtdev);
> + if (ret)
> + return ret;
> +
> + dev_dbg(wdt->pmic->dev, "PMIC Watchdog driver probed\n");
> + return 0;
> +}
> +
> +static const struct of_device_id of_pmic_wdt_match[] = {
> + { .compatible = "st,stpmic1-wdt" },
> + { },
> +};
> +
> +MODULE_DEVICE_TABLE(of, of_pmic_wdt_match);
> +
> +static struct platform_driver stpmic1_wdt_driver = {
> + .probe = pmic_wdt_probe,
> + .driver = {
> + .name = "stpmic1-wdt",
> + .of_match_table = of_pmic_wdt_match,
> + },
> +};
> +module_platform_driver(stpmic1_wdt_driver);
> +
> +MODULE_DESCRIPTION("Watchdog driver for STPMIC1 device");
> +MODULE_AUTHOR("Pascal Paillet");
> +MODULE_LICENSE("GPL v2");
>
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