Messages in this thread | | | Subject | Re: [PATCH 2/2] watchdog: Add new arm_smc_wdt watchdog driver | From | Guenter Roeck <> | Date | Fri, 14 Feb 2020 06:10:23 -0800 |
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On 2/13/20 10:26 PM, Evan Benn wrote: > From: Julius Werner <jwerner@chromium.org> > > This patch adds a stub watchdog driver that can be used on ARM systems
From kernel perspective, this is not a "stub" driver. A stub driver is one that doesn't do anything.
> with a Secure Monitor firmware to forward watchdog operations to > firmware via a Secure Monitor Call. This may be useful for platforms > using TrustZone that want the Secure Monitor firmware to have the final > control over the watchdog. >
As written, one would assume this to work on all systems implementing ARM secure firmware, which is not the case. Please select a different name, and provide information about the systems where this is actually supported.
If it happens to be standardized, we will need a reference to the standard supported. This needs to distinguish from IMX_SC_WDT, which also supports a secure monitor based watchdog (but doesn't claim to be generic).
> Signed-off-by: Julius Werner <jwerner@chromium.org> > Signed-off-by: Evan Benn <evanbenn@chromium.org>
I won't comment on items already covered by Enric. Please address those as well.
> --- > > MAINTAINERS | 1 + > arch/arm64/configs/defconfig | 1 + > drivers/watchdog/Kconfig | 12 +++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/arm_smc_wdt.c | 191 +++++++++++++++++++++++++++++++++ > 5 files changed, 206 insertions(+) > create mode 100644 drivers/watchdog/arm_smc_wdt.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 5c45536e1177..71df3c110fdb 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -1426,6 +1426,7 @@ M: Julius Werner <jwerner@chromium.org> > R: Evan Benn <evanbenn@chromium.org> > S: Maintained > F: devicetree/bindings/watchdog/arm,smc-wdt.yaml > +F: drivers/watchdog/arm_smc_wdt.c > > ARM SMMU DRIVERS > M: Will Deacon <will@kernel.org> > diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig > index b2f667307f82..8527db9e92a6 100644 > --- a/arch/arm64/configs/defconfig > +++ b/arch/arm64/configs/defconfig > @@ -451,6 +451,7 @@ CONFIG_QCOM_TSENS=y > CONFIG_UNIPHIER_THERMAL=y > CONFIG_WATCHDOG=y > CONFIG_ARM_SP805_WATCHDOG=y > +CONFIG_ARM_SMC_WATCHDOG=y > CONFIG_S3C2410_WATCHDOG=y > CONFIG_DW_WATCHDOG=y > CONFIG_SUNXI_WATCHDOG=m > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig > index cec868f8db3f..0f7f93342051 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -857,6 +857,18 @@ config DIGICOLOR_WATCHDOG > To compile this driver as a module, choose M here: the > module will be called digicolor_wdt. > > +config ARM_SMC_WATCHDOG > + tristate "ARM Secure Monitor Call based watchdog support" > + depends on ARM || ARM64
This also depends on HAVE_ARM_SMCCC.
> + select WATCHDOG_CORE > + help > + Say Y here to include support for a watchdog timer > + implemented by the EL3 Secure Monitor on ARM platforms. > + Requires firmware support. > + To compile this driver as a module, choose M here: the > + module will be called arm_smc_wdt. > + > + Extra empty line.
> config LPC18XX_WATCHDOG > tristate "LPC18xx/43xx Watchdog" > depends on ARCH_LPC18XX || COMPILE_TEST > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index 2ee352bf3372..a1e6d83a7659 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -92,6 +92,7 @@ obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o > obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o > obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o > obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o > +obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o > obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o > > # X86 (i386 + ia64 + x86_64) Architecture > diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c > new file mode 100644 > index 000000000000..58e7294136ef > --- /dev/null > +++ b/drivers/watchdog/arm_smc_wdt.c > @@ -0,0 +1,191 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * ARM Secure Monitor Call watchdog driver > + * > + * Copyright 2018 The Chromium OS Authors. All rights reserved. > + * > + * Julius Werner <jwerner@chromium.org> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * Based on mtk_wdt.c > + */ > + > +#include <linux/arm-smccc.h> > +#include <linux/err.h> > +#include <linux/module.h> > +#include <linux/moduleparam.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/types.h> > +#include <linux/watchdog.h> > +#include <uapi/linux/psci.h> > + > +#define DRV_NAME "arm_smc_wdt" > +#define DRV_VERSION "1.0" > + > +#define SMCWD_FUNC_ID 0x82003d06 > + > +enum smcwd_call { > + SMCWD_INFO = 0, > + SMCWD_SET_TIMEOUT = 1, > + SMCWD_ENABLE = 2, > + SMCWD_PET = 3, > +}; > + > +static bool nowayout = WATCHDOG_NOWAYOUT; > +static unsigned int timeout; > + > +static int smcwd_call(enum smcwd_call call, unsigned long arg, > + struct arm_smccc_res *res) > +{ > + struct arm_smccc_res local_res; > + > + if (!res) > + res = &local_res; > + > + arm_smccc_smc(SMCWD_FUNC_ID, call, arg, 0, 0, 0, 0, 0, res); > + > + if ((int)res->a0 == PSCI_RET_NOT_SUPPORTED) > + return -ENOTSUPP;
-ENODEV would be better here.
> + if ((int)res->a0 == PSCI_RET_INVALID_PARAMS) > + return -EINVAL; > + if ((int)res->a0 < 0) > + return -EIO;
Yes, those typecasts are indeed unnecessary.
> + return res->a0; > +} > + > +static int smcwd_ping(struct watchdog_device *wdd) > +{ > + return smcwd_call(SMCWD_PET, 0, NULL); > +} > + > +static int smcwd_set_timeout(struct watchdog_device *wdd, > + unsigned int timeout) > +{ > + int res; > + > + res = smcwd_call(SMCWD_SET_TIMEOUT, timeout, NULL); > + if (!res) > + wdd->timeout = timeout; > + return res; > +} > + > +static int smcwd_stop(struct watchdog_device *wdd) > +{ > + return smcwd_call(SMCWD_ENABLE, 0, NULL); > +} > + > +static int smcwd_start(struct watchdog_device *wdd) > +{ > + return smcwd_call(SMCWD_ENABLE, 1, NULL); > +} > + > +static const struct watchdog_info smcwd_info = { > + .identity = DRV_NAME, > + .options = WDIOF_SETTIMEOUT | > + WDIOF_KEEPALIVEPING | > + WDIOF_MAGICCLOSE, > +}; > + > +static const struct watchdog_ops smcwd_ops = { > + .owner = THIS_MODULE,
Not necessary, and will result in a static analyzer warning.
> + .start = smcwd_start, > + .stop = smcwd_stop, > + .ping = smcwd_ping, > + .set_timeout = smcwd_set_timeout, > +}; > + > +static int smcwd_probe(struct platform_device *pdev) > +{ > + struct watchdog_device *wdd; > + int err; > + struct arm_smccc_res res; > + > + err = smcwd_call(SMCWD_INFO, 0, &res); > + if (err < 0) > + return err; > + > + wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL); > + if (!wdd) > + return -ENOMEM; > + > + platform_set_drvdata(pdev, wdd); > + > + wdd->info = &smcwd_info; > + wdd->ops = &smcwd_ops; > + wdd->timeout = res.a2; > + wdd->max_timeout = res.a2; > + wdd->min_timeout = res.a1; > + wdd->parent = &pdev->dev; > + > + watchdog_set_nowayout(wdd, nowayout); > + watchdog_init_timeout(wdd, timeout, &pdev->dev); > + err = smcwd_set_timeout(wdd, wdd->timeout); > + if (err) > + return err; > + > + err = watchdog_register_device(wdd);
devm_watchdog_register_device() should work here.
> + if (err) > + return err; > + > + dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)\n",
The watchdog is not enabled here, it is only registered.
> + wdd->timeout, nowayout); > + > + return 0; > +} > + > +static void smcwd_shutdown(struct platform_device *pdev) > +{ > + struct watchdog_device *wdd = platform_get_drvdata(pdev); > + > + if (watchdog_active(wdd)) > + smcwd_stop(wdd); > +} > + Please use watchdog_stop_on_reboot().
> +static int smcwd_remove(struct platform_device *pdev) > +{ > + struct watchdog_device *wdd = platform_get_drvdata(pdev); > + > + watchdog_unregister_device(wdd); > + > + return 0; > +} > + > +static const struct of_device_id smcwd_dt_ids[] = { > + { .compatible = "arm,smc-wdt" }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(of, smcwd_dt_ids); > + > +static struct platform_driver smcwd_driver = { > + .probe = smcwd_probe, > + .remove = smcwd_remove, > + .shutdown = smcwd_shutdown, > + .driver = { > + .name = DRV_NAME, > + .of_match_table = smcwd_dt_ids, > + }, > +}; > + > +module_platform_driver(smcwd_driver); > + > +module_param(timeout, uint, 0); > +MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds"); > + > +module_param(nowayout, bool, 0); > +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" > + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); > + > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Julius Werner <jwerner@chromium.org>"); > +MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver"); > +MODULE_VERSION(DRV_VERSION); >
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