This is currently supported in firmware deployed on oak, hana and elm mt8173
chromebook devices. The kernel driver is written to be a generic SMC
watchdog driver.
Arm Trusted Firmware upstreaming review:
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/3405
Patch to add oak, hana, elm device tree:
https://lore.kernel.org/linux-arm-kernel/[email protected]/
I would like to add the device tree support after the above patch is
accepted.
Changes in v2:
- Change name arm > mt8173
- use watchdog_stop_on_reboot
- use watchdog_stop_on_unregister
- use devm_watchdog_register_device
- remove smcwd_shutdown, smcwd_remove
- change error codes
Evan Benn (1):
dt-bindings: watchdog: Add mt8173,smc-wdt watchdog
Julius Werner (1):
watchdog: Add new mt8173_smc_wdt watchdog driver
.../bindings/watchdog/mt8173,smc-wdt.yaml | 30 ++++
MAINTAINERS | 7 +
arch/arm64/configs/defconfig | 1 +
drivers/watchdog/Kconfig | 13 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/mt8173_smc_wdt.c | 160 ++++++++++++++++++
6 files changed, 212 insertions(+)
create mode 100644 Documentation/devicetree/bindings/watchdog/mt8173,smc-wdt.yaml
create mode 100644 drivers/watchdog/mt8173_smc_wdt.c
--
2.25.0.265.gbab2e86ba0-goog
From: Julius Werner <[email protected]>
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 <[email protected]>
Signed-off-by: Evan Benn <[email protected]>
---
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/mt8173_smc_wdt.c | 160 ++++++++++++++++++++++++++++++
5 files changed, 176 insertions(+)
create mode 100644 drivers/watchdog/mt8173_smc_wdt.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 59e8779363c12..94e295e16e128 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1426,6 +1426,7 @@ M: Julius Werner <[email protected]>
R: Evan Benn <[email protected]>
S: Maintained
F: devicetree/bindings/watchdog/mt8173,smc-wdt.yaml
+F: drivers/watchdog/mt8173_smc_wdt.c
ARM SMMU DRIVERS
M: Will Deacon <[email protected]>
diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index b2f667307f829..11d94c9258b79 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_MT8173_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 cec868f8db3f9..b4e55db7a4dcf 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -857,6 +857,19 @@ config DIGICOLOR_WATCHDOG
To compile this driver as a module, choose M here: the
module will be called digicolor_wdt.
+config MT8173_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 2ee352bf3372d..d1381234892ef 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-$(CONFIG_MT8173_SMC_WATCHDOG) += mt8173_smc_wdt.o
obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
# X86 (i386 + ia64 + x86_64) Architecture
diff --git a/drivers/watchdog/mt8173_smc_wdt.c b/drivers/watchdog/mt8173_smc_wdt.c
new file mode 100644
index 0000000000000..681aa42c7d277
--- /dev/null
+++ b/drivers/watchdog/mt8173_smc_wdt.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ARM Secure Monitor Call watchdog driver
+ *
+ * Copyright 2020 Google LLC.
+ * Julius Werner <[email protected]>
+ * 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 "mt8173_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 (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(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 = {
+ .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_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 = "mt8173,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 <[email protected]>");
+MODULE_DESCRIPTION("ARM Secure Monitor Call Watchdog Driver");
+MODULE_VERSION(DRV_VERSION);
--
2.25.0.265.gbab2e86ba0-goog