[PATCH v2 0/4] add meson secure watchdog driver

[PATCH v2 0/4] add meson secure watchdog driver

[Xingyu Chen]

The watchdog controller on the Meson-A/C series SoCs is moved to secure world,
We have to call SMC instruction to trap the ATF for watchdog operation. These
operations are different from previous SoCs, so we introduce a new watchdog
driver to support this kind of SoCs.

Changes since v1 at [0]:
- add a new dependency in Kconfig
- simplify/add the return operation
- remove useless ping operation when setting the timeout
- fix some return values
- fix the license statement

[0]:https://lore.kernel.org/linux-amlogic/1570874721-36077-1-git-send-email-xingyu.chen@amlogic.com

Xingyu Chen (4):
  firmware: meson_sm: add new SMC ID support for accessing secure
    watchdog
  dt-bindings: watchdog: add new binding for meson secure watchdog
  watchdog: add meson secure watchdog driver
  arm64: dts: a1: add secure watchdog controller

 .../bindings/watchdog/amlogic,meson-sec-wdt.yaml   |  34 ++++
 arch/arm64/boot/dts/amlogic/meson-a1.dtsi          |   6 +
 drivers/firmware/meson/meson_sm.c                  |   1 +
 drivers/watchdog/Kconfig                           |  17 ++
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/meson_sec_wdt.c                   | 187 +++++++++++++++++++++
 include/linux/firmware/meson/meson_sm.h            |   1 +
 7 files changed, 247 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml
 create mode 100644 drivers/watchdog/meson_sec_wdt.c

-- 
2.7.4

[PATCH v2 1/4] firmware: meson_sm: add new SMC ID support for accessing secure watchdog

[Xingyu Chen]

The new SMC ID is used to access secure registers by meson secure
watchdog driver.

Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
---
 drivers/firmware/meson/meson_sm.c       | 1 +
 include/linux/firmware/meson/meson_sm.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/firmware/meson/meson_sm.c b/drivers/firmware/meson/meson_sm.c
index 1d5b4d7..46a44de 100644
--- a/drivers/firmware/meson/meson_sm.c
+++ b/drivers/firmware/meson/meson_sm.c
@@ -44,6 +44,7 @@ static const struct meson_sm_chip gxbb_chip = {
 		CMD(SM_EFUSE_WRITE,	0x82000031),
 		CMD(SM_EFUSE_USER_MAX,	0x82000033),
 		CMD(SM_GET_CHIP_ID,	0x82000044),
+		CMD(SM_WATCHDOG_OPS,	0x82000086),
 		{ /* sentinel */ },
 	},
 };
diff --git a/include/linux/firmware/meson/meson_sm.h b/include/linux/firmware/meson/meson_sm.h
index 6669e2a..0934718 100644
--- a/include/linux/firmware/meson/meson_sm.h
+++ b/include/linux/firmware/meson/meson_sm.h
@@ -12,6 +12,7 @@ enum {
 	SM_EFUSE_WRITE,
 	SM_EFUSE_USER_MAX,
 	SM_GET_CHIP_ID,
+	SM_WATCHDOG_OPS,
 };
 
 struct meson_sm_firmware;
-- 
2.7.4

[PATCH v2 2/4] dt-bindings: watchdog: add new binding for meson secure watchdog

[Xingyu Chen]

The binding targets the Meson-A/C series compatible SoCs, in which the
watchdog registers are in secure world.

Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
---
 .../bindings/watchdog/amlogic,meson-sec-wdt.yaml   | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml

diff --git a/Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml b/Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml
new file mode 100644
index 00000000..0bbc807
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/amlogic,meson-sec-wdt.yaml
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+# Copyright (c) 2019 Amlogic, Inc
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/power/amlogic,meson-sec-wdt.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Amlogic Meson Secure Watchdog Timer
+
+maintainers:
+  - Xingyu Chen <xingyu.chen@amlogic.com>
+
+description: |+
+  Secure Watchdog Timer used in Meson-A/C series Compatible SoCs
+
+properties:
+  compatible:
+    enum:
+      - amlogic,meson-sec-wdt
+
+  secure-monitor:
+    description: phandle to the secure-monitor node
+    $ref: /schemas/types.yaml#/definitions/phandle
+
+required:
+  - compatible
+  - secure-monitor
+
+examples:
+  - |
+    watchdog {
+          compatible = "amlogic,meson-sec-wdt";
+          secure-monitor = <&sm>;
+    };
-- 
2.7.4

[PATCH v2 3/4] watchdog: add meson secure watchdog driver

[Xingyu Chen]

The watchdog controller on the Meson-A/C series SoCs is moved to secure
world, watchdog operation needs to be done in secure EL3 mode via ATF,
Non-secure world can call SMC instruction to trap to AFT for watchdog
operation.

Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
---
 drivers/watchdog/Kconfig         |  17 ++++
 drivers/watchdog/Makefile        |   1 +
 drivers/watchdog/meson_sec_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100644 drivers/watchdog/meson_sec_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 58e7c10..e84be42 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called meson_gxbb_wdt.
 
+config MESON_SEC_WATCHDOG
+	tristate "Amlogic Meson Secure watchdog support"
+	depends on MESON_SM
+	depends on ARCH_MESON || COMPILE_TEST
+	select WATCHDOG_CORE
+	help
+	  The watchdog controller on the Meson-A/C series SoCs is moved to
+	  secure world, watchdog operation needs to be done in secure EL3
+	  mode via ATF, non-secure world can call SMC instruction to trap
+	  to ATF for the watchdog operation.
+
+	  Say Y here if watchdog controller on Meson SoCs is located in
+	  secure world.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called meson_sec_wdt.
+
 config MESON_WATCHDOG
 	tristate "Amlogic Meson SoCs watchdog support"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 2ee352b..5e6b73d 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -78,6 +78,7 @@ obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o
 obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
 obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
 obj-$(CONFIG_MESON_GXBB_WATCHDOG) += meson_gxbb_wdt.o
+obj-$(CONFIG_MESON_SEC_WATCHDOG) += meson_sec_wdt.o
 obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
 obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
 obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
diff --git a/drivers/watchdog/meson_sec_wdt.c b/drivers/watchdog/meson_sec_wdt.c
new file mode 100644
index 00000000..86bd87c
--- /dev/null
+++ b/drivers/watchdog/meson_sec_wdt.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (c) 2019 Amlogic, Inc. All rights reserved.
+ * Author: Xingyu Chen <xingyu.chen@amlogic.com>
+ *
+ */
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+#include <linux/firmware/meson/meson_sm.h>
+
+#define MESON_SIP_WDT_DISABLE		0x1
+#define MESON_SIP_WDT_ENABLE		0x2
+#define MESON_SIP_WDT_PING		0x3
+#define MESON_SIP_WDT_INIT		0x4
+#define MESON_SIP_WDT_RESETNOW		0x5
+#define MESON_SIP_WDT_SETTIMEOUT	0x6
+#define MESON_SIP_WDT_GETTIMELEFT	0x7
+
+#define DEFAULT_TIMEOUT			30 /* seconds */
+
+/*
+ * Watchdog timer tick is set to 1ms in secfw side, and tick count is
+ * stored in the bit[16-31] of WATCHDOG_CNT register, so the maximum
+ * timeout value is 0xffff ms.
+ */
+#define MAX_TIMEOUT_MS			0xFFFF
+
+struct meson_sec_wdt {
+	struct watchdog_device wdt_dev;
+	struct meson_sm_firmware *fw;
+};
+
+static int meson_sec_wdt_start(struct watchdog_device *wdt_dev)
+{
+	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
+			     MESON_SIP_WDT_ENABLE, 0, 0, 0, 0);
+}
+
+static int meson_sec_wdt_stop(struct watchdog_device *wdt_dev)
+{
+	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
+			     MESON_SIP_WDT_DISABLE, 0, 0, 0, 0);
+}
+
+static int meson_sec_wdt_ping(struct watchdog_device *wdt_dev)
+{
+	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
+			     MESON_SIP_WDT_PING, 0, 0, 0, 0);
+}
+
+static int meson_sec_wdt_set_timeout(struct watchdog_device *wdt_dev,
+				     unsigned int timeout)
+{
+	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	wdt_dev->timeout = timeout;
+
+	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
+			     MESON_SIP_WDT_SETTIMEOUT,
+			     wdt_dev->timeout, 0, 0, 0);
+}
+
+static unsigned int meson_sec_wdt_get_timeleft(struct watchdog_device *wdt_dev)
+{
+	int ret;
+	unsigned int timeleft;
+	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
+
+	ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, &timeleft,
+			    MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
+
+	if (ret)
+		return ret;
+
+	return timeleft;
+}
+
+static const struct watchdog_ops meson_sec_wdt_ops = {
+	.start = meson_sec_wdt_start,
+	.stop = meson_sec_wdt_stop,
+	.ping = meson_sec_wdt_ping,
+	.set_timeout = meson_sec_wdt_set_timeout,
+	.get_timeleft = meson_sec_wdt_get_timeleft,
+};
+
+static const struct watchdog_info meson_sec_wdt_info = {
+	.identity = "Meson Secure Watchdog Timer",
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+};
+
+static int __maybe_unused meson_sec_wdt_resume(struct device *dev)
+{
+	struct meson_sec_wdt *data = dev_get_drvdata(dev);
+
+	if (watchdog_active(&data->wdt_dev))
+		return meson_sec_wdt_start(&data->wdt_dev);
+
+	return 0;
+}
+
+static int __maybe_unused meson_sec_wdt_suspend(struct device *dev)
+{
+	struct meson_sec_wdt *data = dev_get_drvdata(dev);
+
+	if (watchdog_active(&data->wdt_dev))
+		return meson_sec_wdt_stop(&data->wdt_dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops meson_sec_wdt_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(meson_sec_wdt_suspend, meson_sec_wdt_resume)
+};
+
+static const struct of_device_id meson_sec_wdt_dt_ids[] = {
+	 { .compatible = "amlogic,meson-sec-wdt", },
+	 { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, meson_sec_wdt_dt_ids);
+
+static int meson_sec_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct meson_sec_wdt *data;
+	struct device_node *sm_np;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	sm_np = of_parse_phandle(pdev->dev.of_node, "secure-monitor", 0);
+	if (!sm_np) {
+		dev_err(&pdev->dev, "no secure-monitor node\n");
+		return -EINVAL;
+	}
+
+	data->fw = meson_sm_get(sm_np);
+	of_node_put(sm_np);
+	if (!data->fw)
+		return -EPROBE_DEFER;
+
+	platform_set_drvdata(pdev, data);
+
+	data->wdt_dev.parent = dev;
+	data->wdt_dev.info = &meson_sec_wdt_info;
+	data->wdt_dev.ops = &meson_sec_wdt_ops;
+	data->wdt_dev.max_hw_heartbeat_ms = MAX_TIMEOUT_MS;
+	data->wdt_dev.min_timeout = 1;
+	data->wdt_dev.timeout = DEFAULT_TIMEOUT;
+	watchdog_set_drvdata(&data->wdt_dev, data);
+
+	ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
+			    MESON_SIP_WDT_INIT,
+			    data->wdt_dev.timeout, 0, 0, 0);
+	if (ret)
+		return ret;
+
+	watchdog_stop_on_reboot(&data->wdt_dev);
+
+	return devm_watchdog_register_device(dev, &data->wdt_dev);
+}
+
+static struct platform_driver meson_sec_wdt_driver = {
+	.probe	= meson_sec_wdt_probe,
+	.driver = {
+		.name = "meson-sec-wdt",
+		.pm = &meson_sec_wdt_pm_ops,
+		.of_match_table	= meson_sec_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(meson_sec_wdt_driver);
+
+MODULE_AUTHOR("Xingyu Chen <xingyu.chen@amlogic.com>");
+MODULE_DESCRIPTION("Amlogic Secure Watchdog Timer Driver");
+MODULE_LICENSE("Dual MIT/GPL");
-- 
2.7.4

[PATCH v2 4/4] arm64: dts: a1: add secure watchdog controller

[Xingyu Chen]

Enable secure watchdog controller for Meson-A1 SoC

Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
---
 arch/arm64/boot/dts/amlogic/meson-a1.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/boot/dts/amlogic/meson-a1.dtsi b/arch/arm64/boot/dts/amlogic/meson-a1.dtsi
index 7210ad0..047c323 100644
--- a/arch/arm64/boot/dts/amlogic/meson-a1.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-a1.dtsi
@@ -93,6 +93,12 @@
 				clock-names = "xtal", "pclk", "baud";
 				status = "disabled";
 			};
+
+			watchdog {
+				compatible = "amlogic,meson-sec-wdt";
+				secure-monitor = <&sm>;
+				status = "okay";
+			};
 		};
 
 		gic: interrupt-controller@ff901000 {
-- 
2.7.4

Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver

[Guenter Roeck]

On 10/18/19 1:33 AM, Xingyu Chen wrote:
> The watchdog controller on the Meson-A/C series SoCs is moved to secure
> world, watchdog operation needs to be done in secure EL3 mode via ATF,
> Non-secure world can call SMC instruction to trap to AFT for watchdog
> operation.
> 
> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
> ---
>   drivers/watchdog/Kconfig         |  17 ++++
>   drivers/watchdog/Makefile        |   1 +
>   drivers/watchdog/meson_sec_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++
>   3 files changed, 205 insertions(+)
>   create mode 100644 drivers/watchdog/meson_sec_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 58e7c10..e84be42 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
>   	  To compile this driver as a module, choose M here: the
>   	  module will be called meson_gxbb_wdt.
>   
> +config MESON_SEC_WATCHDOG
> +	tristate "Amlogic Meson Secure watchdog support"
> +	depends on MESON_SM
> +	depends on ARCH_MESON || COMPILE_TEST

This dependency is pointless. MESON_SM already depends on ARCH_MESON,
thus specifying "COMPILE_TEST" here adds no value but only
creates confusion.

> +	select WATCHDOG_CORE
> +	help
> +	  The watchdog controller on the Meson-A/C series SoCs is moved to
> +	  secure world, watchdog operation needs to be done in secure EL3
> +	  mode via ATF, non-secure world can call SMC instruction to trap
> +	  to ATF for the watchdog operation.
> +
> +	  Say Y here if watchdog controller on Meson SoCs is located in
> +	  secure world.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called meson_sec_wdt.
> +
>   config MESON_WATCHDOG
>   	tristate "Amlogic Meson SoCs watchdog support"
>   	depends on ARCH_MESON || COMPILE_TEST
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 2ee352b..5e6b73d 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -78,6 +78,7 @@ obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o
>   obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
>   obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
>   obj-$(CONFIG_MESON_GXBB_WATCHDOG) += meson_gxbb_wdt.o
> +obj-$(CONFIG_MESON_SEC_WATCHDOG) += meson_sec_wdt.o
>   obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
>   obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
>   obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
> diff --git a/drivers/watchdog/meson_sec_wdt.c b/drivers/watchdog/meson_sec_wdt.c
> new file mode 100644
> index 00000000..86bd87c
> --- /dev/null
> +++ b/drivers/watchdog/meson_sec_wdt.c
> @@ -0,0 +1,187 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright (c) 2019 Amlogic, Inc. All rights reserved.
> + * Author: Xingyu Chen <xingyu.chen@amlogic.com>
> + *
> + */
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>
> +#include <linux/watchdog.h>
> +#include <linux/firmware/meson/meson_sm.h>
> +
> +#define MESON_SIP_WDT_DISABLE		0x1
> +#define MESON_SIP_WDT_ENABLE		0x2
> +#define MESON_SIP_WDT_PING		0x3
> +#define MESON_SIP_WDT_INIT		0x4
> +#define MESON_SIP_WDT_RESETNOW		0x5
> +#define MESON_SIP_WDT_SETTIMEOUT	0x6
> +#define MESON_SIP_WDT_GETTIMELEFT	0x7
> +
> +#define DEFAULT_TIMEOUT			30 /* seconds */
> +
> +/*
> + * Watchdog timer tick is set to 1ms in secfw side, and tick count is
> + * stored in the bit[16-31] of WATCHDOG_CNT register, so the maximum
> + * timeout value is 0xffff ms.
> + */
> +#define MAX_TIMEOUT_MS			0xFFFF
> +
> +struct meson_sec_wdt {
> +	struct watchdog_device wdt_dev;
> +	struct meson_sm_firmware *fw;
> +};
> +
> +static int meson_sec_wdt_start(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> +			     MESON_SIP_WDT_ENABLE, 0, 0, 0, 0);
> +}
> +
> +static int meson_sec_wdt_stop(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> +			     MESON_SIP_WDT_DISABLE, 0, 0, 0, 0);
> +}
> +
> +static int meson_sec_wdt_ping(struct watchdog_device *wdt_dev)
> +{
> +	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> +			     MESON_SIP_WDT_PING, 0, 0, 0, 0);
> +}
> +
> +static int meson_sec_wdt_set_timeout(struct watchdog_device *wdt_dev,
> +				     unsigned int timeout)
> +{
> +	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	wdt_dev->timeout = timeout;
> +
> +	return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> +			     MESON_SIP_WDT_SETTIMEOUT,
> +			     wdt_dev->timeout, 0, 0, 0);
> +}
> +
> +static unsigned int meson_sec_wdt_get_timeleft(struct watchdog_device *wdt_dev)
> +{
> +	int ret;
> +	unsigned int timeleft;
> +	struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
> +
> +	ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, &timeleft,
> +			    MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
> +
> +	if (ret)
> +		return ret;

Meh, that doesn't work. I just realized that the return type is unsigned,
so returning a negative error code is pointless. Guess we'll have to
live with returning 0 in this case after all. I wonder if we should
fix the API and return an integer (with negative error code), but that
is a different question.

Sorry for the confusion - I should have noticed that before.

> +
> +	return timeleft;
> +}
> +
> +static const struct watchdog_ops meson_sec_wdt_ops = {
> +	.start = meson_sec_wdt_start,
> +	.stop = meson_sec_wdt_stop,
> +	.ping = meson_sec_wdt_ping,
> +	.set_timeout = meson_sec_wdt_set_timeout,
> +	.get_timeleft = meson_sec_wdt_get_timeleft,
> +};
> +
> +static const struct watchdog_info meson_sec_wdt_info = {
> +	.identity = "Meson Secure Watchdog Timer",
> +	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> +};
> +
> +static int __maybe_unused meson_sec_wdt_resume(struct device *dev)
> +{
> +	struct meson_sec_wdt *data = dev_get_drvdata(dev);
> +
> +	if (watchdog_active(&data->wdt_dev))
> +		return meson_sec_wdt_start(&data->wdt_dev);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused meson_sec_wdt_suspend(struct device *dev)
> +{
> +	struct meson_sec_wdt *data = dev_get_drvdata(dev);
> +
> +	if (watchdog_active(&data->wdt_dev))
> +		return meson_sec_wdt_stop(&data->wdt_dev);
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops meson_sec_wdt_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(meson_sec_wdt_suspend, meson_sec_wdt_resume)
> +};
> +
> +static const struct of_device_id meson_sec_wdt_dt_ids[] = {
> +	 { .compatible = "amlogic,meson-sec-wdt", },
> +	 { /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, meson_sec_wdt_dt_ids);
> +
> +static int meson_sec_wdt_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct meson_sec_wdt *data;
> +	struct device_node *sm_np;
> +	int ret;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	sm_np = of_parse_phandle(pdev->dev.of_node, "secure-monitor", 0);
> +	if (!sm_np) {
> +		dev_err(&pdev->dev, "no secure-monitor node\n");
> +		return -EINVAL;
> +	}
> +
> +	data->fw = meson_sm_get(sm_np);
> +	of_node_put(sm_np);
> +	if (!data->fw)
> +		return -EPROBE_DEFER;
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	data->wdt_dev.parent = dev;
> +	data->wdt_dev.info = &meson_sec_wdt_info;
> +	data->wdt_dev.ops = &meson_sec_wdt_ops;
> +	data->wdt_dev.max_hw_heartbeat_ms = MAX_TIMEOUT_MS;
> +	data->wdt_dev.min_timeout = 1;
> +	data->wdt_dev.timeout = DEFAULT_TIMEOUT;
> +	watchdog_set_drvdata(&data->wdt_dev, data);
> +
> +	ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
> +			    MESON_SIP_WDT_INIT,
> +			    data->wdt_dev.timeout, 0, 0, 0);
> +	if (ret)
> +		return ret;
> +
> +	watchdog_stop_on_reboot(&data->wdt_dev);
> +
> +	return devm_watchdog_register_device(dev, &data->wdt_dev);
> +}
> +
> +static struct platform_driver meson_sec_wdt_driver = {
> +	.probe	= meson_sec_wdt_probe,
> +	.driver = {
> +		.name = "meson-sec-wdt",
> +		.pm = &meson_sec_wdt_pm_ops,
> +		.of_match_table	= meson_sec_wdt_dt_ids,
> +	},
> +};
> +
> +module_platform_driver(meson_sec_wdt_driver);
> +
> +MODULE_AUTHOR("Xingyu Chen <xingyu.chen@amlogic.com>");
> +MODULE_DESCRIPTION("Amlogic Secure Watchdog Timer Driver");
> +MODULE_LICENSE("Dual MIT/GPL");
> 

Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver

[Xingyu Chen]

Hi, Guenter

On 2019/10/21 0:56, Guenter Roeck wrote:
> On 10/18/19 1:33 AM, Xingyu Chen wrote:
>> The watchdog controller on the Meson-A/C series SoCs is moved to secure
>> world, watchdog operation needs to be done in secure EL3 mode via ATF,
>> Non-secure world can call SMC instruction to trap to AFT for watchdog
>> operation.
>>
>> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
>> ---
>>   drivers/watchdog/Kconfig         |  17 ++++
>>   drivers/watchdog/Makefile        |   1 +
>>   drivers/watchdog/meson_sec_wdt.c | 187 
>> +++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 205 insertions(+)
>>   create mode 100644 drivers/watchdog/meson_sec_wdt.c
>>
>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>> index 58e7c10..e84be42 100644
>> --- a/drivers/watchdog/Kconfig
>> +++ b/drivers/watchdog/Kconfig
>> @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
>>         To compile this driver as a module, choose M here: the
>>         module will be called meson_gxbb_wdt.
>> +config MESON_SEC_WATCHDOG
>> +    tristate "Amlogic Meson Secure watchdog support"
>> +    depends on MESON_SM
>> +    depends on ARCH_MESON || COMPILE_TEST
> 
> This dependency is pointless. MESON_SM already depends on ARCH_MESON,
> thus specifying "COMPILE_TEST" here adds no value but only
> creates confusion.
Thanks for your analysis, perhaps i should remove the line below.
- depends on ARCH_MESON || COMPILE_TEST

Is it ok to modify code above like this ?
> 
>> +    select WATCHDOG_CORE
>> +    help
>> +      The watchdog controller on the Meson-A/C series SoCs is moved to
>> +      secure world, watchdog operation needs to be done in secure EL3
>> +      mode via ATF, non-secure world can call SMC instruction to trap
>> +      to ATF for the watchdog operation.
>> +
>> +      Say Y here if watchdog controller on Meson SoCs is located in
>> +      secure world.
>> +
>> +      To compile this driver as a module, choose M here: the
>> +      module will be called meson_sec_wdt.
>> +
>>   config MESON_WATCHDOG
>>       tristate "Amlogic Meson SoCs watchdog support"
>>       depends on ARCH_MESON || COMPILE_TEST
>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>> index 2ee352b..5e6b73d 100644
>> --- a/drivers/watchdog/Makefile
>> +++ b/drivers/watchdog/Makefile
>> @@ -78,6 +78,7 @@ obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o
>>   obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
>>   obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
>>   obj-$(CONFIG_MESON_GXBB_WATCHDOG) += meson_gxbb_wdt.o
>> +obj-$(CONFIG_MESON_SEC_WATCHDOG) += meson_sec_wdt.o
>>   obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
>>   obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
>>   obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
>> diff --git a/drivers/watchdog/meson_sec_wdt.c 
>> b/drivers/watchdog/meson_sec_wdt.c
>> new file mode 100644
>> index 00000000..86bd87c
>> --- /dev/null
>> +++ b/drivers/watchdog/meson_sec_wdt.c
>> @@ -0,0 +1,187 @@
>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>> +/*
>> + * Copyright (c) 2019 Amlogic, Inc. All rights reserved.
>> + * Author: Xingyu Chen <xingyu.chen@amlogic.com>
>> + *
>> + */
>> +#include <linux/err.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/types.h>
>> +#include <linux/watchdog.h>
>> +#include <linux/firmware/meson/meson_sm.h>
>> +
>> +#define MESON_SIP_WDT_DISABLE        0x1
>> +#define MESON_SIP_WDT_ENABLE        0x2
>> +#define MESON_SIP_WDT_PING        0x3
>> +#define MESON_SIP_WDT_INIT        0x4
>> +#define MESON_SIP_WDT_RESETNOW        0x5
>> +#define MESON_SIP_WDT_SETTIMEOUT    0x6
>> +#define MESON_SIP_WDT_GETTIMELEFT    0x7
>> +
>> +#define DEFAULT_TIMEOUT            30 /* seconds */
>> +
>> +/*
>> + * Watchdog timer tick is set to 1ms in secfw side, and tick count is
>> + * stored in the bit[16-31] of WATCHDOG_CNT register, so the maximum
>> + * timeout value is 0xffff ms.
>> + */
>> +#define MAX_TIMEOUT_MS            0xFFFF
>> +
>> +struct meson_sec_wdt {
>> +    struct watchdog_device wdt_dev;
>> +    struct meson_sm_firmware *fw;
>> +};
>> +
>> +static int meson_sec_wdt_start(struct watchdog_device *wdt_dev)
>> +{
>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>> +                 MESON_SIP_WDT_ENABLE, 0, 0, 0, 0);
>> +}
>> +
>> +static int meson_sec_wdt_stop(struct watchdog_device *wdt_dev)
>> +{
>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>> +                 MESON_SIP_WDT_DISABLE, 0, 0, 0, 0);
>> +}
>> +
>> +static int meson_sec_wdt_ping(struct watchdog_device *wdt_dev)
>> +{
>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>> +                 MESON_SIP_WDT_PING, 0, 0, 0, 0);
>> +}
>> +
>> +static int meson_sec_wdt_set_timeout(struct watchdog_device *wdt_dev,
>> +                     unsigned int timeout)
>> +{
>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    wdt_dev->timeout = timeout;
>> +
>> +    return meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>> +                 MESON_SIP_WDT_SETTIMEOUT,
>> +                 wdt_dev->timeout, 0, 0, 0);
>> +}
>> +
>> +static unsigned int meson_sec_wdt_get_timeleft(struct watchdog_device 
>> *wdt_dev)
>> +{
>> +    int ret;
>> +    unsigned int timeleft;
>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>> +
>> +    ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, &timeleft,
>> +                MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
>> +
>> +    if (ret)
>> +        return ret;
> 
> Meh, that doesn't work. I just realized that the return type is unsigned,
> so returning a negative error code is pointless. Guess we'll have to
> live with returning 0 in this case after all. I wonder if we should
> fix the API and return an integer (with negative error code), but that
> is a different question.
Thanks for your review.

IMO, if returning an integer, and the value which copy to user buf 
should be formatted with %d instead of %u (see timeleft_show), it will 
cause the max value of timeleft is reduced from 4294967295 to 
2147483647. but i'am not sure whether it will bring risk.

So i also think returning 0 may be better in this case.
> 
> Sorry for the confusion - I should have noticed that before.
> 
>> +
>> +    return timeleft;
>> +}
>> +
>> +static const struct watchdog_ops meson_sec_wdt_ops = {
>> +    .start = meson_sec_wdt_start,
>> +    .stop = meson_sec_wdt_stop,
>> +    .ping = meson_sec_wdt_ping,
>> +    .set_timeout = meson_sec_wdt_set_timeout,
>> +    .get_timeleft = meson_sec_wdt_get_timeleft,
>> +};
>> +
>> +static const struct watchdog_info meson_sec_wdt_info = {
>> +    .identity = "Meson Secure Watchdog Timer",
>> +    .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 
>> WDIOF_MAGICCLOSE,
>> +};
>> +
>> +static int __maybe_unused meson_sec_wdt_resume(struct device *dev)
>> +{
>> +    struct meson_sec_wdt *data = dev_get_drvdata(dev);
>> +
>> +    if (watchdog_active(&data->wdt_dev))
>> +        return meson_sec_wdt_start(&data->wdt_dev);
>> +
>> +    return 0;
>> +}
>> +
>> +static int __maybe_unused meson_sec_wdt_suspend(struct device *dev)
>> +{
>> +    struct meson_sec_wdt *data = dev_get_drvdata(dev);
>> +
>> +    if (watchdog_active(&data->wdt_dev))
>> +        return meson_sec_wdt_stop(&data->wdt_dev);
>> +
>> +    return 0;
>> +}
>> +
>> +static const struct dev_pm_ops meson_sec_wdt_pm_ops = {
>> +    SET_SYSTEM_SLEEP_PM_OPS(meson_sec_wdt_suspend, meson_sec_wdt_resume)
>> +};
>> +
>> +static const struct of_device_id meson_sec_wdt_dt_ids[] = {
>> +     { .compatible = "amlogic,meson-sec-wdt", },
>> +     { /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, meson_sec_wdt_dt_ids);
>> +
>> +static int meson_sec_wdt_probe(struct platform_device *pdev)
>> +{
>> +    struct device *dev = &pdev->dev;
>> +    struct meson_sec_wdt *data;
>> +    struct device_node *sm_np;
>> +    int ret;
>> +
>> +    data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> +    if (!data)
>> +        return -ENOMEM;
>> +
>> +    sm_np = of_parse_phandle(pdev->dev.of_node, "secure-monitor", 0);
>> +    if (!sm_np) {
>> +        dev_err(&pdev->dev, "no secure-monitor node\n");
>> +        return -EINVAL;
>> +    }
>> +
>> +    data->fw = meson_sm_get(sm_np);
>> +    of_node_put(sm_np);
>> +    if (!data->fw)
>> +        return -EPROBE_DEFER;
>> +
>> +    platform_set_drvdata(pdev, data);
>> +
>> +    data->wdt_dev.parent = dev;
>> +    data->wdt_dev.info = &meson_sec_wdt_info;
>> +    data->wdt_dev.ops = &meson_sec_wdt_ops;
>> +    data->wdt_dev.max_hw_heartbeat_ms = MAX_TIMEOUT_MS;
>> +    data->wdt_dev.min_timeout = 1;
>> +    data->wdt_dev.timeout = DEFAULT_TIMEOUT;
>> +    watchdog_set_drvdata(&data->wdt_dev, data);
>> +
>> +    ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, NULL,
>> +                MESON_SIP_WDT_INIT,
>> +                data->wdt_dev.timeout, 0, 0, 0);
>> +    if (ret)
>> +        return ret;
>> +
>> +    watchdog_stop_on_reboot(&data->wdt_dev);
>> +
>> +    return devm_watchdog_register_device(dev, &data->wdt_dev);
>> +}
>> +
>> +static struct platform_driver meson_sec_wdt_driver = {
>> +    .probe    = meson_sec_wdt_probe,
>> +    .driver = {
>> +        .name = "meson-sec-wdt",
>> +        .pm = &meson_sec_wdt_pm_ops,
>> +        .of_match_table    = meson_sec_wdt_dt_ids,
>> +    },
>> +};
>> +
>> +module_platform_driver(meson_sec_wdt_driver);
>> +
>> +MODULE_AUTHOR("Xingyu Chen <xingyu.chen@amlogic.com>");
>> +MODULE_DESCRIPTION("Amlogic Secure Watchdog Timer Driver");
>> +MODULE_LICENSE("Dual MIT/GPL");
>>
> 
> .
> 

Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver

[Guenter Roeck]

On 10/21/19 1:03 AM, Xingyu Chen wrote:
> Hi, Guenter
> 
> On 2019/10/21 0:56, Guenter Roeck wrote:
>> On 10/18/19 1:33 AM, Xingyu Chen wrote:
>>> The watchdog controller on the Meson-A/C series SoCs is moved to secure
>>> world, watchdog operation needs to be done in secure EL3 mode via ATF,
>>> Non-secure world can call SMC instruction to trap to AFT for watchdog
>>> operation.
>>>
>>> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
>>> ---
>>>   drivers/watchdog/Kconfig         |  17 ++++
>>>   drivers/watchdog/Makefile        |   1 +
>>>   drivers/watchdog/meson_sec_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++
>>>   3 files changed, 205 insertions(+)
>>>   create mode 100644 drivers/watchdog/meson_sec_wdt.c
>>>
>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>> index 58e7c10..e84be42 100644
>>> --- a/drivers/watchdog/Kconfig
>>> +++ b/drivers/watchdog/Kconfig
>>> @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
>>>         To compile this driver as a module, choose M here: the
>>>         module will be called meson_gxbb_wdt.
>>> +config MESON_SEC_WATCHDOG
>>> +    tristate "Amlogic Meson Secure watchdog support"
>>> +    depends on MESON_SM
>>> +    depends on ARCH_MESON || COMPILE_TEST
>>
>> This dependency is pointless. MESON_SM already depends on ARCH_MESON,
>> thus specifying "COMPILE_TEST" here adds no value but only
>> creates confusion.
> Thanks for your analysis, perhaps i should remove the line below.
> - depends on ARCH_MESON || COMPILE_TEST
> 
> Is it ok to modify code above like this ?

Yes.
[ ... ]

>>> +static unsigned int meson_sec_wdt_get_timeleft(struct watchdog_device *wdt_dev)
>>> +{
>>> +    int ret;
>>> +    unsigned int timeleft;
>>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>> +
>>> +    ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, &timeleft,
>>> +                MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
>>> +
>>> +    if (ret)
>>> +        return ret;
>>
>> Meh, that doesn't work. I just realized that the return type is unsigned,
>> so returning a negative error code is pointless. Guess we'll have to
>> live with returning 0 in this case after all. I wonder if we should
>> fix the API and return an integer (with negative error code), but that
>> is a different question.
> Thanks for your review.
> 
> IMO, if returning an integer, and the value which copy to user buf should be formatted with %d instead of %u (see timeleft_show), it will cause the max value of timeleft is reduced from 4294967295 to 2147483647. but i'am not sure whether it will bring risk.

Not that it matters right now, but I don't think that limiting 'timeleft'
reporting to 2147483647 seconds, or ~68 years, would cause any risk.
It would just be a large patch changing several drivers all at once,
that is all.

> 
> So i also think returning 0 may be better in this case.

Yes, please do that.

Thanks,
Guenter

Re: [PATCH v2 3/4] watchdog: add meson secure watchdog driver

[Xingyu Chen]

Hi, Guenter

On 2019/10/21 21:38, Guenter Roeck wrote:
> On 10/21/19 1:03 AM, Xingyu Chen wrote:
>> Hi, Guenter
>>
>> On 2019/10/21 0:56, Guenter Roeck wrote:
>>> On 10/18/19 1:33 AM, Xingyu Chen wrote:
>>>> The watchdog controller on the Meson-A/C series SoCs is moved to secure
>>>> world, watchdog operation needs to be done in secure EL3 mode via ATF,
>>>> Non-secure world can call SMC instruction to trap to AFT for watchdog
>>>> operation.
>>>>
>>>> Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
>>>> ---
>>>>   drivers/watchdog/Kconfig         |  17 ++++
>>>>   drivers/watchdog/Makefile        |   1 +
>>>>   drivers/watchdog/meson_sec_wdt.c | 187 
>>>> +++++++++++++++++++++++++++++++++++++++
>>>>   3 files changed, 205 insertions(+)
>>>>   create mode 100644 drivers/watchdog/meson_sec_wdt.c
>>>>
>>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>>> index 58e7c10..e84be42 100644
>>>> --- a/drivers/watchdog/Kconfig
>>>> +++ b/drivers/watchdog/Kconfig
>>>> @@ -826,6 +826,23 @@ config MESON_GXBB_WATCHDOG
>>>>         To compile this driver as a module, choose M here: the
>>>>         module will be called meson_gxbb_wdt.
>>>> +config MESON_SEC_WATCHDOG
>>>> +    tristate "Amlogic Meson Secure watchdog support"
>>>> +    depends on MESON_SM
>>>> +    depends on ARCH_MESON || COMPILE_TEST
>>>
>>> This dependency is pointless. MESON_SM already depends on ARCH_MESON,
>>> thus specifying "COMPILE_TEST" here adds no value but only
>>> creates confusion.
>> Thanks for your analysis, perhaps i should remove the line below.
>> - depends on ARCH_MESON || COMPILE_TEST
>>
>> Is it ok to modify code above like this ?
> 
> Yes.
Thanks, fix it in next version.

> [ ... ]
> 
>>>> +static unsigned int meson_sec_wdt_get_timeleft(struct 
>>>> watchdog_device *wdt_dev)
>>>> +{
>>>> +    int ret;
>>>> +    unsigned int timeleft;
>>>> +    struct meson_sec_wdt *data = watchdog_get_drvdata(wdt_dev);
>>>> +
>>>> +    ret = meson_sm_call(data->fw, SM_WATCHDOG_OPS, Thanks&timeleft,
>>>> +                MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
>>>> +
>>>> +    if (ret)
>>>> +        return ret;
>>>
>>> Meh, that doesn't work. I just realized that the return type is 
>>> unsigned,
>>> so returning a negative error code is pointless. Guess we'll have to
>>> live with returning 0 in this case after all. I wonder if we should
>>> fix the API and return an integer (with negative error code), but that
>>> is a different question.
>> Thanks for your review.
>>
>> IMO, if returning an integer, and the value which copy to user buf 
>> should be formatted with %d instead of %u (see timeleft_show), it will 
>> cause the max value of timeleft is reduced from 4294967295 to 
>> 2147483647. but i'am not sure whether it will bring risk.
> 
> Not that it matters right now, but I don't think that limiting 'timeleft'
> reporting to 2147483647 seconds, or ~68 years, would cause any risk.
> It would just be a large patch changing several drivers all at once,
> that is all.
> 
>>
>> So i also think returning 0 may be better in this case.
> 
> Yes, please do that.
Thanks, fix it in next version.
> 
> Thanks,
> Guenter
> 
> .
>