| Message ID | 20200423143945.v5.2.Ia92bb4d4ce84bcefeba1d00aaa1c1e919b6164ef@changeid (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Add a watchdog driver that uses ARM Secure Monitor Calls. | expand |
On 4/22/20 9:40 PM, Evan Benn wrote: > From: Julius Werner <jwerner@chromium.org> > > This patch adds a watchdog driver that can be used on ARM systems > with the appropriate watchdog implemented in Secure Monitor firmware. > The driver communicates with 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. > > This is implemented on mt8173 chromebook devices oak, elm and hana in > arm trusted firmware file plat/mediatek/mt8173/drivers/wdt/wdt.c. > > Signed-off-by: Julius Werner <jwerner@chromium.org> > Signed-off-by: Evan Benn <evanbenn@chromium.org> > Your patch doesn't apply to the mainline kernel, not even with "patch -p 1". What is your kernel baseline ? Guenter > --- > > Changes in v5: > - Make timeleft return 0 on error > - Use type punning on smc_func_id to save an alloc > - Change compatible to arm,smc-wdt > > Changes in v4: > - Get smc-id from of property > - Return a1 instead of a0 in timeleft > > Changes in v3: > - Add optional get_timeleft op > - change name to arm_smc_wdt > > Changes in v2: > - use watchdog_stop_on_reboot > - use watchdog_stop_on_unregister > - use devm_watchdog_register_device > - remove smcwd_shutdown, smcwd_remove > - change error codes > > MAINTAINERS | 1 + > arch/arm64/configs/defconfig | 1 + > drivers/watchdog/Kconfig | 13 +++ > drivers/watchdog/Makefile | 1 + > drivers/watchdog/arm_smc_wdt.c | 189 +++++++++++++++++++++++++++++++++ > 5 files changed, 205 insertions(+) > create mode 100644 drivers/watchdog/arm_smc_wdt.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 0f2b39767bfa9..2b782bbff200a 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -1462,6 +1462,7 @@ 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 24e534d850454..0619df80f7575 100644 > --- a/arch/arm64/configs/defconfig > +++ b/arch/arm64/configs/defconfig > @@ -513,6 +513,7 @@ CONFIG_UNIPHIER_THERMAL=y > CONFIG_WATCHDOG=y > CONFIG_ARM_SP805_WATCHDOG=y > CONFIG_ARM_SBSA_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 0663c604bd642..c440b576d23bf 100644 > --- a/drivers/watchdog/Kconfig > +++ b/drivers/watchdog/Kconfig > @@ -867,6 +867,19 @@ 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 > + depends on OF > + 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. > + > config LPC18XX_WATCHDOG > tristate "LPC18xx/43xx Watchdog" > depends on ARCH_LPC18XX || COMPILE_TEST > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > index 6de2e4ceef190..97bed1d3d97cb 100644 > --- a/drivers/watchdog/Makefile > +++ b/drivers/watchdog/Makefile > @@ -94,6 +94,7 @@ obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o > obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o > obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o > obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o > +obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o > > # X86 (i386 + ia64 + x86_64) Architecture > obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o > diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c > new file mode 100644 > index 0000000000000..7e14909bddda2 > --- /dev/null > +++ b/drivers/watchdog/arm_smc_wdt.c > @@ -0,0 +1,189 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * ARM Secure Monitor Call watchdog driver > + * > + * Copyright 2020 Google LLC. > + * Julius Werner <jwerner@chromium.org> > + * 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" > + > +enum smcwd_call { > + SMCWD_INIT = 0, > + SMCWD_SET_TIMEOUT = 1, > + SMCWD_ENABLE = 2, > + SMCWD_PET = 3, > + SMCWD_GET_TIMELEFT = 4, > +}; > + > +static bool nowayout = WATCHDOG_NOWAYOUT; > +static unsigned int timeout; > + > +static int smcwd_call(struct watchdog_device *wdd, 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((u32)(uintptr_t)watchdog_get_drvdata(wdd), call, arg, 0, > + 0, 0, 0, 0, res); > + > + if (res->a0 == PSCI_RET_NOT_SUPPORTED) > + return -ENODEV; > + if (res->a0 == PSCI_RET_INVALID_PARAMS) > + return -EINVAL; > + if (res->a0 != PSCI_RET_SUCCESS) > + return -EIO; > + return 0; > +} > + > +static int smcwd_ping(struct watchdog_device *wdd) > +{ > + return smcwd_call(wdd, SMCWD_PET, 0, NULL); > +} > + > +static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd) > +{ > + struct arm_smccc_res res; > + > + smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res); > + if (res.a0) > + return 0; > + return res.a1; > +} > + > +static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout) > +{ > + int res; > + > + res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL); > + if (!res) > + wdd->timeout = timeout; > + return res; > +} > + > +static int smcwd_stop(struct watchdog_device *wdd) > +{ > + return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL); > +} > + > +static int smcwd_start(struct watchdog_device *wdd) > +{ > + return smcwd_call(wdd, 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 = { > + .start = smcwd_start, > + .stop = smcwd_stop, > + .ping = smcwd_ping, > + .set_timeout = smcwd_set_timeout, > +}; > + > +static const struct watchdog_ops smcwd_timeleft_ops = { > + .start = smcwd_start, > + .stop = smcwd_stop, > + .ping = smcwd_ping, > + .set_timeout = smcwd_set_timeout, > + .get_timeleft = smcwd_get_timeleft, > +}; > + > +static int smcwd_probe(struct platform_device *pdev) > +{ > + struct watchdog_device *wdd; > + int err; > + struct arm_smccc_res res; > + u32 smc_func_id; > + > + wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL); > + if (!wdd) > + return -ENOMEM; > + platform_set_drvdata(pdev, wdd); > + > + err = of_property_read_u32(pdev->dev.of_node, "arm,smc-id", > + &smc_func_id); > + if (err < 0) > + return err; > + watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id); > + > + err = smcwd_call(wdd, SMCWD_INIT, 0, &res); > + if (err < 0) > + return err; > + > + wdd->info = &smcwd_info; > + /* get_timeleft is optional */ > + if (smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL)) > + wdd->ops = &smcwd_ops; > + else > + wdd->ops = &smcwd_timeleft_ops; > + wdd->timeout = res.a2; > + wdd->max_timeout = res.a2; > + wdd->min_timeout = res.a1; > + wdd->parent = &pdev->dev; > + > + watchdog_stop_on_reboot(wdd); > + watchdog_stop_on_unregister(wdd); > + watchdog_set_nowayout(wdd, nowayout); > + watchdog_init_timeout(wdd, timeout, &pdev->dev); > + err = smcwd_set_timeout(wdd, wdd->timeout); > + if (err) > + return err; > + > + err = devm_watchdog_register_device(&pdev->dev, wdd); > + if (err) > + return err; > + > + dev_info(&pdev->dev, > + "Watchdog registered (timeout=%d sec, nowayout=%d)\n", > + wdd->timeout, nowayout); > + > + return 0; > +} > + > +static const struct of_device_id smcwd_dt_ids[] = { > + { .compatible = "arm,smc-wdt" }, > + {} > +}; > +MODULE_DEVICE_TABLE(of, smcwd_dt_ids); > + > +static struct platform_driver smcwd_driver = { > + .probe = smcwd_probe, > + .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); >
> + err = of_property_read_u32(pdev->dev.of_node, "arm,smc-id", > + &smc_func_id); > + if (err < 0) > + return err; > + watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id); Your device tree binding says there's a default and this is optional. I think you need to change the code so that that's actually true.
On Fri, Apr 24, 2020 at 8:17 AM Julius Werner <jwerner@chromium.org> wrote: > > > + err = of_property_read_u32(pdev->dev.of_node, "arm,smc-id", > > + &smc_func_id); > > + if (err < 0) > > + return err; > > + watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id); > > Your device tree binding says there's a default and this is optional. > I think you need to change the code so that that's actually true. I think I have misunderstood the device tree json-schema spec. My intention was for the device tree to fill in a default value in the dtb for arm,smc-id if it was omitted in the dts. But now I see that does not seem to happen, I cannot really find any documentation of `default`, so I will just put a documentation string in instead and force the default in the driver.
> I think I have misunderstood the device tree json-schema spec. > My intention was for the device tree to fill in a default value in the dtb for > arm,smc-id if it was omitted in the dts. But now I see that does not seem to > happen, I cannot really find any documentation of `default`, so I will just put > a documentation string in instead and force the default in the driver. The bindings in Documentation/device-tree are just for informational purposes, they do not have any direct effect on anything. If you want there to be a default, you'll have to write the kernel code to fill it in.
diff --git a/MAINTAINERS b/MAINTAINERS index 0f2b39767bfa9..2b782bbff200a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1462,6 +1462,7 @@ 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 24e534d850454..0619df80f7575 100644 --- a/arch/arm64/configs/defconfig +++ b/arch/arm64/configs/defconfig @@ -513,6 +513,7 @@ CONFIG_UNIPHIER_THERMAL=y CONFIG_WATCHDOG=y CONFIG_ARM_SP805_WATCHDOG=y CONFIG_ARM_SBSA_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 0663c604bd642..c440b576d23bf 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig @@ -867,6 +867,19 @@ 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 + depends on OF + 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. + config LPC18XX_WATCHDOG tristate "LPC18xx/43xx Watchdog" depends on ARCH_LPC18XX || COMPILE_TEST diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index 6de2e4ceef190..97bed1d3d97cb 100644 --- a/drivers/watchdog/Makefile +++ b/drivers/watchdog/Makefile @@ -94,6 +94,7 @@ obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o +obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o # X86 (i386 + ia64 + x86_64) Architecture obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c new file mode 100644 index 0000000000000..7e14909bddda2 --- /dev/null +++ b/drivers/watchdog/arm_smc_wdt.c @@ -0,0 +1,189 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ARM Secure Monitor Call watchdog driver + * + * Copyright 2020 Google LLC. + * Julius Werner <jwerner@chromium.org> + * 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" + +enum smcwd_call { + SMCWD_INIT = 0, + SMCWD_SET_TIMEOUT = 1, + SMCWD_ENABLE = 2, + SMCWD_PET = 3, + SMCWD_GET_TIMELEFT = 4, +}; + +static bool nowayout = WATCHDOG_NOWAYOUT; +static unsigned int timeout; + +static int smcwd_call(struct watchdog_device *wdd, 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((u32)(uintptr_t)watchdog_get_drvdata(wdd), call, arg, 0, + 0, 0, 0, 0, res); + + if (res->a0 == PSCI_RET_NOT_SUPPORTED) + return -ENODEV; + if (res->a0 == PSCI_RET_INVALID_PARAMS) + return -EINVAL; + if (res->a0 != PSCI_RET_SUCCESS) + return -EIO; + return 0; +} + +static int smcwd_ping(struct watchdog_device *wdd) +{ + return smcwd_call(wdd, SMCWD_PET, 0, NULL); +} + +static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd) +{ + struct arm_smccc_res res; + + smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, &res); + if (res.a0) + return 0; + return res.a1; +} + +static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout) +{ + int res; + + res = smcwd_call(wdd, SMCWD_SET_TIMEOUT, timeout, NULL); + if (!res) + wdd->timeout = timeout; + return res; +} + +static int smcwd_stop(struct watchdog_device *wdd) +{ + return smcwd_call(wdd, SMCWD_ENABLE, 0, NULL); +} + +static int smcwd_start(struct watchdog_device *wdd) +{ + return smcwd_call(wdd, 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 = { + .start = smcwd_start, + .stop = smcwd_stop, + .ping = smcwd_ping, + .set_timeout = smcwd_set_timeout, +}; + +static const struct watchdog_ops smcwd_timeleft_ops = { + .start = smcwd_start, + .stop = smcwd_stop, + .ping = smcwd_ping, + .set_timeout = smcwd_set_timeout, + .get_timeleft = smcwd_get_timeleft, +}; + +static int smcwd_probe(struct platform_device *pdev) +{ + struct watchdog_device *wdd; + int err; + struct arm_smccc_res res; + u32 smc_func_id; + + wdd = devm_kzalloc(&pdev->dev, sizeof(*wdd), GFP_KERNEL); + if (!wdd) + return -ENOMEM; + platform_set_drvdata(pdev, wdd); + + err = of_property_read_u32(pdev->dev.of_node, "arm,smc-id", + &smc_func_id); + if (err < 0) + return err; + watchdog_set_drvdata(wdd, (void *)(uintptr_t)smc_func_id); + + err = smcwd_call(wdd, SMCWD_INIT, 0, &res); + if (err < 0) + return err; + + wdd->info = &smcwd_info; + /* get_timeleft is optional */ + if (smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL)) + wdd->ops = &smcwd_ops; + else + wdd->ops = &smcwd_timeleft_ops; + wdd->timeout = res.a2; + wdd->max_timeout = res.a2; + wdd->min_timeout = res.a1; + wdd->parent = &pdev->dev; + + watchdog_stop_on_reboot(wdd); + watchdog_stop_on_unregister(wdd); + watchdog_set_nowayout(wdd, nowayout); + watchdog_init_timeout(wdd, timeout, &pdev->dev); + err = smcwd_set_timeout(wdd, wdd->timeout); + if (err) + return err; + + err = devm_watchdog_register_device(&pdev->dev, wdd); + if (err) + return err; + + dev_info(&pdev->dev, + "Watchdog registered (timeout=%d sec, nowayout=%d)\n", + wdd->timeout, nowayout); + + return 0; +} + +static const struct of_device_id smcwd_dt_ids[] = { + { .compatible = "arm,smc-wdt" }, + {} +}; +MODULE_DEVICE_TABLE(of, smcwd_dt_ids); + +static struct platform_driver smcwd_driver = { + .probe = smcwd_probe, + .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);