watchdog: menf21bmc_wdt: Introduce MEN 14F021P00 BMC Watchdog driver

Added driver to support the 14F021P00 BMC Watchdog.
The BMC is a Board Management Controller including watchdog functionality.

Signed-off-by: Andreas Werner <andreas.werner@men.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/watchdog/Kconfig

@@ -95,6 +95,16 @@ config GPIO_WATCHDOG
 	  If you say yes here you get support for watchdog device
 	  controlled through GPIO-line.
 
+config MENF21BMC_WATCHDOG
+	tristate "MEN 14F021P00 BMC Watchdog"
+	depends on MFD_MENF21BMC
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the MEN 14F021P00 BMC Watchdog.
+
+	  This driver can also be built as a module. If so the module
+	  will be called menf21bmc_wdt.
+
 config WM831X_WATCHDOG
 	tristate "WM831x watchdog"
 	depends on MFD_WM831X

drivers/watchdog/Makefile

@@ -178,3 +178,4 @@ obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
 obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o

drivers/watchdog/menf21bmc_wdt.c

@@ -0,0 +1,203 @@
+/*
+ *  MEN 14F021P00 Board Management Controller (BMC) Watchdog Driver.
+ *
+ *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+
+#define DEVNAME "menf21bmc_wdt"
+
+#define BMC_CMD_WD_ON		0x11
+#define BMC_CMD_WD_OFF		0x12
+#define BMC_CMD_WD_TRIG		0x13
+#define BMC_CMD_WD_TIME		0x14
+#define BMC_CMD_WD_STATE	0x17
+#define BMC_WD_OFF_VAL		0x69
+#define BMC_CMD_RST_RSN		0x92
+
+#define BMC_WD_TIMEOUT_MIN	1	/* in sec */
+#define BMC_WD_TIMEOUT_MAX	6553	/* in sec */
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct menf21bmc_wdt {
+	struct watchdog_device wdt;
+	struct i2c_client *i2c_client;
+};
+
+static int menf21bmc_wdt_set_bootstatus(struct menf21bmc_wdt *data)
+{
+	int rst_rsn;
+
+	rst_rsn = i2c_smbus_read_byte_data(data->i2c_client, BMC_CMD_RST_RSN);
+	if (rst_rsn < 0)
+		return rst_rsn;
+
+	if (rst_rsn == 0x02)
+		data->wdt.bootstatus |= WDIOF_CARDRESET;
+	else if (rst_rsn == 0x05)
+		data->wdt.bootstatus |= WDIOF_EXTERN1;
+	else if (rst_rsn == 0x06)
+		data->wdt.bootstatus |= WDIOF_EXTERN2;
+	else if (rst_rsn == 0x0A)
+		data->wdt.bootstatus |= WDIOF_POWERUNDER;
+
+	return 0;
+}
+
+static int menf21bmc_wdt_start(struct watchdog_device *wdt)
+{
+	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
+
+	return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_ON);
+}
+
+static int menf21bmc_wdt_stop(struct watchdog_device *wdt)
+{
+	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
+
+	return i2c_smbus_write_byte_data(drv_data->i2c_client,
+					 BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
+}
+
+static int
+menf21bmc_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
+{
+	int ret;
+	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
+
+	/*
+	 *  BMC Watchdog does have a resolution of 100ms.
+	 *  Watchdog API defines the timeout in seconds, so we have to
+	 *  multiply the value.
+	 */
+	ret = i2c_smbus_write_word_data(drv_data->i2c_client,
+					BMC_CMD_WD_TIME, timeout * 10);
+	if (ret < 0)
+		return ret;
+
+	wdt->timeout = timeout;
+
+	return 0;
+}
+
+static int menf21bmc_wdt_ping(struct watchdog_device *wdt)
+{
+	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
+
+	return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_TRIG);
+}
+
+static const struct watchdog_info menf21bmc_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+	.identity = DEVNAME,
+};
+
+static const struct watchdog_ops menf21bmc_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= menf21bmc_wdt_start,
+	.stop		= menf21bmc_wdt_stop,
+	.ping		= menf21bmc_wdt_ping,
+	.set_timeout	= menf21bmc_wdt_settimeout,
+};
+
+static int menf21bmc_wdt_probe(struct platform_device *pdev)
+{
+	int ret, bmc_timeout;
+	struct menf21bmc_wdt *drv_data;
+	struct i2c_client *i2c_client = to_i2c_client(pdev->dev.parent);
+
+	drv_data = devm_kzalloc(&pdev->dev,
+				sizeof(struct menf21bmc_wdt), GFP_KERNEL);
+	if (!drv_data)
+		return -ENOMEM;
+
+	drv_data->wdt.ops = &menf21bmc_wdt_ops;
+	drv_data->wdt.info = &menf21bmc_wdt_info;
+	drv_data->wdt.min_timeout = BMC_WD_TIMEOUT_MIN;
+	drv_data->wdt.max_timeout = BMC_WD_TIMEOUT_MAX;
+	drv_data->i2c_client = i2c_client;
+
+	/*
+	 * Get the current wdt timeout value from the BMC because
+	 * the BMC will save the value set before if the system restarts.
+	 */
+	bmc_timeout = i2c_smbus_read_word_data(drv_data->i2c_client,
+					       BMC_CMD_WD_TIME);
+	if (bmc_timeout < 0) {
+		dev_err(&pdev->dev, "failed to get current WDT timeout\n");
+		return bmc_timeout;
+	}
+
+	watchdog_init_timeout(&drv_data->wdt, bmc_timeout / 10, &pdev->dev);
+	watchdog_set_nowayout(&drv_data->wdt, nowayout);
+	watchdog_set_drvdata(&drv_data->wdt, drv_data);
+	platform_set_drvdata(pdev, drv_data);
+
+	ret = menf21bmc_wdt_set_bootstatus(drv_data);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to set Watchdog bootstatus\n");
+		return ret;
+	}
+
+	ret = watchdog_register_device(&drv_data->wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register Watchdog device\n");
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "MEN 14F021P00 BMC Watchdog device enabled\n");
+
+	return 0;
+}
+
+static int menf21bmc_wdt_remove(struct platform_device *pdev)
+{
+	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
+
+	dev_warn(&pdev->dev,
+		 "Unregister MEN 14F021P00 BMC Watchdog device, board may reset\n");
+
+	watchdog_unregister_device(&drv_data->wdt);
+
+	return 0;
+}
+
+static void menf21bmc_wdt_shutdown(struct platform_device *pdev)
+{
+	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
+
+	i2c_smbus_write_word_data(drv_data->i2c_client,
+				  BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
+}
+
+static struct  platform_driver menf21bmc_wdt = {
+	.driver		= {
+		.owner = THIS_MODULE,
+		.name	= DEVNAME,
+	},
+	.probe		= menf21bmc_wdt_probe,
+	.remove		= menf21bmc_wdt_remove,
+	.shutdown	= menf21bmc_wdt_shutdown,
+};
+
+module_platform_driver(menf21bmc_wdt);
+
+MODULE_DESCRIPTION("MEN 14F021P00 BMC Watchdog driver");
+MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:menf21bmc_wdt");