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Date: Wed, 22 Apr 2020 12:02:47 +0800
From: Xingyu Chen <xingyu.chen@...ogic.com>
To: Evan Benn <evanbenn@...omium.org>,
LKML <linux-kernel@...r.kernel.org>
CC: <jwerner@...omium.org>, Guenter Roeck <linux@...ck-us.net>,
Anson Huang <Anson.Huang@....com>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Catalin Marinas <catalin.marinas@....com>,
"David S. Miller" <davem@...emloft.net>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Leonard Crestez <leonard.crestez@....com>,
Li Yang <leoyang.li@....com>,
Marcin Juszkiewicz <marcin.juszkiewicz@...aro.org>,
Matthias Brugger <matthias.bgg@...il.com>,
Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
Olof Johansson <olof@...om.net>, Rob Herring <robh@...nel.org>,
Shawn Guo <shawnguo@...nel.org>,
Valentin Schneider <valentin.schneider@....com>,
Will Deacon <will@...nel.org>,
Wim Van Sebroeck <wim@...ux-watchdog.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-mediatek@...ts.infradead.org>,
<linux-watchdog@...r.kernel.org>,
Jianxin Pan <jianxin.pan@...ogic.com>,
Yonghui Yu <yonghui.yu@...ogic.com>,
Xingyu Chen <xingyu.chen@...ogic.com>
Subject: Re: [PATCH v2 2/2] watchdog: Add new arm_smc_wdt watchdog driver
Hi,Evan
On 2020/4/21 19:05, Evan Benn wrote:
> From: Julius Werner <jwerner@...omium.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@...omium.org>
> Signed-off-by: Evan Benn <evanbenn@...omium.org>
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
>
> ---
>
> 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 | 194 +++++++++++++++++++++++++++++++++
> 5 files changed, 210 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@...omium.org>
> R: Evan Benn <evanbenn@...omium.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@...nel.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..29d2573b2ca11
> --- /dev/null
> +++ b/drivers/watchdog/arm_smc_wdt.c
> @@ -0,0 +1,194 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ARM Secure Monitor Call watchdog driver
> + *
> + * Copyright 2020 Google LLC.
> + * Julius Werner <jwerner@...omium.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"
> +
> +#define get_smc_func_id(wdd) (*(u32 *)watchdog_get_drvdata(wdd))
> +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(unsigned long smc_func_id, 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(smc_func_id, 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(get_smc_func_id(wdd), SMCWD_PET, 0, NULL);
> +}
> +
> +static unsigned int smcwd_get_timeleft(struct watchdog_device *wdd)
> +{
> + struct arm_smccc_res res;
> +
> + smcwd_call(get_smc_func_id(wdd), SMCWD_GET_TIMELEFT, 0, &res);
> + return res.a1;It should return 0 when the smcwd_call return error according to
Guenter's suggestion at [0]
[0]: https://patchwork.kernel.org/patch/11197781/
Thanks.
> +
> +static int smcwd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
> +{
> + int res;
> +
> + res = smcwd_call(get_smc_func_id(wdd), SMCWD_SET_TIMEOUT, timeout,
> + NULL);
> + if (!res)
> + wdd->timeout = timeout;
> + return res;
> +}
> +
> +static int smcwd_stop(struct watchdog_device *wdd)
> +{
> + return smcwd_call(get_smc_func_id(wdd), SMCWD_ENABLE, 0, NULL);
> +}
> +
[...]
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Julius Werner <jwerner@...omium.org>");
> +MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
> +MODULE_VERSION(DRV_VERSION);
>
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