[PATCH v6 4/5] 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.

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Xingyu Chen <xingyu.chen@xxxxxxxxxxx>
---
 drivers/watchdog/Kconfig         |  16 ++++
 drivers/watchdog/Makefile        |   1 +
 drivers/watchdog/meson_sec_wdt.c | 185 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 202 insertions(+)
 create mode 100644 drivers/watchdog/meson_sec_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1679e0d..5f88325 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -826,6 +826,22 @@ 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
+	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..493cbe8
--- /dev/null
+++ b/drivers/watchdog/meson_sec_wdt.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (c) 2019 Amlogic, Inc. All rights reserved.
+ * Author: Xingyu Chen <xingyu.chen@xxxxxxxxxxx>
+ *
+ */
+#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_A1_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_A1_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_A1_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_A1_WATCHDOG_OPS, NULL,
+			     MESON_SIP_WDT_SETTIMEOUT,
+			     wdt_dev->timeout * 1000, 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_A1_WATCHDOG_OPS, &timeleft,
+			    MESON_SIP_WDT_GETTIMELEFT, 0, 0, 0, 0);
+
+	if (ret)
+		return 0;
+
+	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 = dev_of_node(dev->parent);
+	if (!sm_np)
+		return -EINVAL;
+
+	data->fw = meson_sm_get(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);
+	watchdog_init_timeout(&data->wdt_dev, 0, dev);
+
+	ret = meson_sm_call(data->fw, SM_A1_WATCHDOG_OPS, NULL,
+			    MESON_SIP_WDT_INIT,
+			    data->wdt_dev.timeout * 1000, 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@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Amlogic Secure Watchdog Timer Driver");
+MODULE_LICENSE("Dual MIT/GPL");
-- 
2.7.4