[PATCH 8/8] watchdog: stpmu1: add stpmu1 watchdog driver

[Pascal PAILLET-LME <p.paillet@st.com>]

From: pascal paillet <p.paillet@st.com>

The stpmu1 PMIC embeds a watchdog which is disabled by default. As soon
as the watchdog is started, it must be refreshed periodically otherwise
the PMIC goes off.

Signed-off-by: pascal paillet <p.paillet@st.com>
---
 drivers/watchdog/Kconfig      |  12 +++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/stpmu1_wdt.c | 177 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 190 insertions(+)
 create mode 100644 drivers/watchdog/stpmu1_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9af07fd..2155f4d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -796,6 +796,18 @@ config STM32_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called stm32_iwdg.
 
+config STPMU1_WATCHDOG
+	tristate "STPMU1 PMIC watchdog support"
+	depends on MFD_STPMU1
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include watchdog support embedded into STPMU1 PMIC.
+	  If the watchdog timer expires, stpmu1 shut-down all its power
+	  supplies.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called spmu1_wdt.
+
 config UNIPHIER_WATCHDOG
 	tristate "UniPhier watchdog support"
 	depends on ARCH_UNIPHIER || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 1d3c6b0..c9eba94 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -216,3 +216,4 @@ obj-$(CONFIG_ZIIRAVE_WATCHDOG) += ziirave_wdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
 obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
 obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
+obj-$(CONFIG_STPMU1_WATCHDOG) += stpmu1_wdt.o
diff --git a/drivers/watchdog/stpmu1_wdt.c b/drivers/watchdog/stpmu1_wdt.c
new file mode 100644
index 0000000..57e0afa
--- /dev/null
+++ b/drivers/watchdog/stpmu1_wdt.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
+ * Author: Philippe Peurichard <philippe.peurichard@st.com>,
+ * Pascal Paillet <p.paillet@st.com> for STMicroelectronics.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mfd/stpmu1.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+#include <linux/watchdog.h>
+
+/* WATCHDOG CONTROL REGISTER bit */
+#define WDT_START		BIT(0)
+#define WDT_PING		BIT(1)
+#define WDT_START_MASK		BIT(0)
+#define WDT_PING_MASK		BIT(1)
+
+#define PMIC_WDT_MIN_TIMEOUT 1
+#define PMIC_WDT_MAX_TIMEOUT 256
+
+struct stpmu1_wdt {
+	struct stpmu1_dev *pmic;
+	struct watchdog_device wdtdev;
+	struct notifier_block restart_handler;
+};
+
+static int pmic_wdt_start(struct watchdog_device *wdd)
+{
+	struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	return regmap_update_bits(wdt->pmic->regmap,
+				  WCHDG_CR, WDT_START_MASK, WDT_START);
+}
+
+static int pmic_wdt_stop(struct watchdog_device *wdd)
+{
+	struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	return regmap_update_bits(wdt->pmic->regmap,
+				  WCHDG_CR, WDT_START_MASK, ~WDT_START);
+}
+
+static int pmic_wdt_ping(struct watchdog_device *wdd)
+{
+	struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	return regmap_update_bits(wdt->pmic->regmap,
+				  WCHDG_CR, WDT_PING_MASK, WDT_PING);
+	return ret;
+}
+
+static int pmic_wdt_set_timeout(struct watchdog_device *wdd,
+				unsigned int timeout)
+{
+	struct stpmu1_wdt *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	ret = regmap_write(wdt->pmic->regmap, WCHDG_TIMER_CR, timeout);
+	if (ret)
+		dev_err(wdt->pmic->dev,
+			"Failed to set watchdog timeout (err = %d)\n", ret);
+	else
+		wdd->timeout = PMIC_WDT_MAX_TIMEOUT;
+
+	return ret;
+}
+
+static int pmic_wdt_restart_handler(struct notifier_block *this,
+				    unsigned long mode, void *cmd)
+{
+	struct stpmu1_wdt *wdt = container_of(this,
+						   struct stpmu1_wdt,
+						   restart_handler);
+
+	dev_info(wdt->pmic->dev,
+		 "PMIC Watchdog Elapsed (timeout %d), shutdown of PMIC initiated\n",
+		 wdt->wdtdev.timeout);
+
+	return NOTIFY_DONE;
+}
+
+static const struct watchdog_info pmic_watchdog_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+	.identity = "STPMU1 PMIC Watchdog",
+};
+
+static const struct watchdog_ops pmic_watchdog_ops = {
+	.owner = THIS_MODULE,
+	.start = pmic_wdt_start,
+	.stop = pmic_wdt_stop,
+	.ping = pmic_wdt_ping,
+	.set_timeout = pmic_wdt_set_timeout,
+};
+
+static int pmic_wdt_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct stpmu1_dev *pmic;
+	struct stpmu1_wdt *wdt;
+
+	if (!pdev->dev.parent)
+		return -EINVAL;
+
+	pmic = dev_get_drvdata(pdev->dev.parent);
+	if (!pmic)
+		return -EINVAL;
+
+	wdt = devm_kzalloc(&pdev->dev, sizeof(struct stpmu1_wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdt->pmic = pmic;
+
+	wdt->wdtdev.info = &pmic_watchdog_info;
+	wdt->wdtdev.ops = &pmic_watchdog_ops;
+	wdt->wdtdev.min_timeout = PMIC_WDT_MIN_TIMEOUT;
+	wdt->wdtdev.max_timeout = PMIC_WDT_MAX_TIMEOUT;
+	wdt->wdtdev.timeout = PMIC_WDT_MAX_TIMEOUT;
+
+	wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
+
+	watchdog_set_drvdata(&wdt->wdtdev, wdt);
+	dev_set_drvdata(&pdev->dev, wdt);
+
+	ret = watchdog_register_device(&wdt->wdtdev);
+	if (ret)
+		return ret;
+
+	wdt->restart_handler.notifier_call = pmic_wdt_restart_handler;
+	wdt->restart_handler.priority = 128;
+	ret = register_restart_handler(&wdt->restart_handler);
+	if (ret) {
+		dev_err(wdt->pmic->dev, "failed to register restart handler\n");
+		return ret;
+	}
+
+	dev_dbg(wdt->pmic->dev, "PMIC Watchdog driver probed\n");
+	return 0;
+}
+
+static int pmic_wdt_remove(struct platform_device *pdev)
+{
+	struct stpmu1_wdt *wdt = dev_get_drvdata(&pdev->dev);
+
+	unregister_restart_handler(&wdt->restart_handler);
+	watchdog_unregister_device(&wdt->wdtdev);
+
+	return 0;
+}
+
+static const struct of_device_id of_pmic_wdt_match[] = {
+	{ .compatible = "st,stpmu1-wdt" },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, of_pmic_wdt_match);
+
+static struct platform_driver stpmu1_wdt_driver = {
+	.probe = pmic_wdt_probe,
+	.remove = pmic_wdt_remove,
+	.driver = {
+		.name = "stpmu1-wdt",
+		.of_match_table = of_pmic_wdt_match,
+	},
+};
+module_platform_driver(stpmu1_wdt_driver);
+
+MODULE_AUTHOR("philippe.peurichard@st.com>");
+MODULE_DESCRIPTION("Watchdog driver for STPMU1 device");
+MODULE_LICENSE("GPL");
-- 
1.9.1