[RFC,4/5] wdt-dmec: watchdog support for dmec

diff --git a/drivers/staging/dmec/Kconfig b/drivers/staging/dmec/Kconfig
index 9c4a8e5..eddf0bb 100644
--- a/drivers/staging/dmec/Kconfig
+++ b/drivers/staging/dmec/Kconfig
@@ -27,3 +27,14 @@  config GPIO_DMEC
 
 	  To compile this driver as a module, say M here: the module will be
           called gpio-dmec
+
+config WDT_DMEC
+	tristate "Data Modul Watchdog"
+	depends on MFD_DMEC
+	select WATCHDOG_CORE
+	help
+	  Say Y to enable support for a watchdog on a Data Modul embedded
+	  controllers.
+
+	  To compile this driver as a module, say M here: the module will be
+          called wdt-dmec
diff --git a/drivers/staging/dmec/Makefile b/drivers/staging/dmec/Makefile
index b71b27b..8b363cc 100644
--- a/drivers/staging/dmec/Makefile
+++ b/drivers/staging/dmec/Makefile
@@ -1,3 +1,4 @@ 
 obj-$(CONFIG_MFD_DMEC)		+= dmec-core.o
 obj-$(CONFIG_I2C_DMEC)		+= i2c-dmec.o
 obj-$(CONFIG_GPIO_DMEC) 	+= gpio-dmec.o
+obj-$(CONFIG_WDT_DMEC)		+= wdt-dmec.o
diff --git a/drivers/staging/dmec/wdt-dmec.c b/drivers/staging/dmec/wdt-dmec.c
new file mode 100644
index 0000000..714ed11
--- /dev/null
+++ b/drivers/staging/dmec/wdt-dmec.c
@@ -0,0 +1,569 @@ 
+/*
+ * Watchdog driver for Data Modul AG Embedded Controller
+ *
+ * Copyright (C) 2016 Zahari Doychev, Data Modul AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/bitops.h>
+
+#include "dmec.h"
+
+#define DMEC_WDT_VER		0x30
+#define DMEC_WDT_SRV		0x30
+#define DMEC_WDT_CFG		0x31
+#define DMEC_WDT_S0CFG		0x32
+#define DMEC_WDT_S0MOD0		0x33
+#define DMEC_WDT_S0MOD1		0x34
+#define DMEC_WDT_S1CFG		(DMEC_WDT_S0CFG + 3)
+#define DMEC_WDT_S1MOD0		(DMEC_WDT_S0MOD0 + 3)
+#define DMEC_WDT_S1MOD1		(DMEC_WDT_S0MOD1 + 3)
+#define DMEC_WDT_S2CFG		(DMEC_WDT_S1CFG + 3)
+#define DMEC_WDT_S2MOD0		(DMEC_WDT_S1MOD0 + 3)
+#define DMEC_WDT_S2MOD1		(DMEC_WDT_S1MOD1 + 3)
+
+#define DMEC_WDT_EN		BIT(0)
+#define DMEC_WDT_LOCK		BIT(1)
+#define DMEC_WDT_WIN_MODE	BIT(2)
+#define DMEC_WDT_AL		BIT(3)
+
+#define DMEC_WDT_PRESCALER	BIT(4)
+#define DMEC_WDT_WDTEN		BIT(3)
+#define DMEC_WDT_WDSTS		BIT(5)
+
+#define DMEC_WDT_TIMEOUT_MIN	1 /* s */
+#define DMEC_WDT_TIMEOUT_MAX	(2 * 3600) /* s */
+
+#define DMEC_WDT_TIME_MAX	(65 * 1000)
+
+/* S0 used only during boot */
+#define DEFAULT_S0_TIMEOUT	0
+#define DEFAULT_S1_TIMEOUT	3
+#define DEFAULT_S2_TIMEOUT	5
+
+enum wdt_actions {
+	WDT_DISABLE = 0,
+	WDT_DELAY,
+	WDT_RESET,
+	WDT_SYSIRQ0,
+	WDT_SYSIRQ1,
+	WDT_SYSIRQ2,
+	WDT_IRQ,
+	WDT_RESERVED
+};
+
+enum wdt_stages {
+	S0,
+	S1,
+	S2
+};
+
+static unsigned int s1_timeout = DEFAULT_S1_TIMEOUT;
+module_param(s1_timeout, uint, 0644);
+MODULE_PARM_DESC(s1_timeout,
+		 "Watchdog stage 1 timeout in [s], default=3");
+
+static unsigned int s2_timeout = DEFAULT_S2_TIMEOUT;
+module_param(s2_timeout, uint, 0644);
+MODULE_PARM_DESC(s2_timeout,
+		 "Watchdog stage 2 timeout in [s], default=5");
+
+static enum wdt_actions action = WDT_DELAY;
+module_param(action, uint, 0644);
+MODULE_PARM_DESC(action,
+		 "Watchdog action for stage 1, default=1 (delay)");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0644);
+MODULE_PARM_DESC(nowayout,
+		 "Watchdog cannot be stopped once started (default="
+				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static bool win_mode;
+module_param(win_mode, bool, 0644);
+MODULE_PARM_DESC(win_mode, "Use watchdog window mode, default=0");
+
+static bool stop_on_reboot;
+module_param(stop_on_reboot, bool, 0644);
+MODULE_PARM_DESC(stop_on_reboot, "stop watchdog on system reboot, default=0");
+
+struct dmec_wdt_data {
+	struct watchdog_device	wdd;
+	struct regmap *regmap;
+	unsigned int s1_time;
+	unsigned int s2_time;
+	unsigned int status;
+	unsigned int boot_cfg;
+	bool boot_mode;
+};
+
+static int dmec_wdt_set_stage_action(struct dmec_wdt_data *wdat,
+				     unsigned int stage,
+				     enum wdt_actions action)
+{
+	unsigned int offset = DMEC_WDT_S0CFG + (3 * stage);
+	unsigned int val;
+
+	regmap_read(wdat->regmap, offset, &val);
+	val &= ~DMEC_WDT_WDSTS;
+	val |= action | DMEC_WDT_WDTEN;
+	regmap_write(wdat->regmap, offset, val);
+
+	return 0;
+}
+
+static int dmec_wdt_clear_action(struct dmec_wdt_data *wdat, int stage)
+{
+	unsigned int val;
+
+	regmap_read(wdat->regmap, DMEC_WDT_S0CFG + 3 * stage, &val);
+	val |= DMEC_WDT_WDSTS;
+	val &= ~0xf;
+	regmap_write(wdat->regmap, DMEC_WDT_S0CFG + 3 * stage, val);
+
+	return 0;
+}
+
+static unsigned int dmec_wdt_get_stage_timeout(struct dmec_wdt_data *wdat,
+					       unsigned int stage)
+{
+	unsigned int val, timeout = 0, cfg;
+
+	regmap_read(wdat->regmap, DMEC_WDT_S0CFG + 3 * stage, &cfg);
+	regmap_read(wdat->regmap, DMEC_WDT_S0MOD0 + 3 * stage, &val);
+	timeout = val;
+	regmap_read(wdat->regmap, DMEC_WDT_S0MOD1 + 3 * stage, &val);
+	timeout |= (val << 8);
+
+	if (cfg & DMEC_WDT_PRESCALER)
+		timeout <<= 7;
+
+	return timeout / 1000;
+}
+
+static int dmec_wdt_set_stage_timeout(struct dmec_wdt_data *wdat,
+				      unsigned int stage,
+				      unsigned int timeout)
+{
+	unsigned int val;
+
+	timeout *= 1000;
+	if (timeout > DMEC_WDT_TIME_MAX) {
+		/* enable prescaler */
+		regmap_read(wdat->regmap, DMEC_WDT_S0CFG + (3 * stage), &val);
+		val |= DMEC_WDT_PRESCALER;
+		regmap_write(wdat->regmap, DMEC_WDT_S0CFG + (3 * stage), val);
+		timeout >>= 7;
+	} else {
+		regmap_read(wdat->regmap, DMEC_WDT_S0CFG + (3 * stage), &val);
+		val &= ~DMEC_WDT_PRESCALER;
+		regmap_write(wdat->regmap, DMEC_WDT_S0CFG + (3 * stage), val);
+	}
+
+	val = timeout & 0xff;
+	regmap_write(wdat->regmap, DMEC_WDT_S0MOD0 + (3 * stage), val);
+	val = (timeout >> 8) & 0xff;
+	regmap_write(wdat->regmap, DMEC_WDT_S0MOD1 + (3 * stage), val);
+
+	return 0;
+}
+
+static int dmec_wdt_set_timeouts(struct dmec_wdt_data *wdat)
+{
+	dmec_wdt_clear_action(wdat, S0);
+	dmec_wdt_clear_action(wdat, S1);
+	dmec_wdt_clear_action(wdat, S2);
+
+	wdat->s1_time = s1_timeout;
+	wdat->s2_time = s2_timeout;
+	dmec_wdt_set_stage_timeout(wdat, S1, s1_timeout);
+	dmec_wdt_set_stage_timeout(wdat, S2, s2_timeout);
+	dmec_wdt_set_stage_action(wdat, S2, WDT_RESET);
+
+	return 0;
+}
+
+static int dmec_wdt_stop(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+
+	regmap_update_bits(wdat->regmap, DMEC_WDT_CFG, DMEC_WDT_EN, 0);
+
+	return 0;
+}
+
+static int dmec_wdt_start(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+
+	regmap_update_bits(wdat->regmap, DMEC_WDT_CFG,
+			   DMEC_WDT_EN, DMEC_WDT_EN);
+
+	wdat->boot_mode = false;
+
+	return 0;
+}
+
+static int dmec_wdt_ping(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+	unsigned int val;
+
+	/* We should try avoiding resets in window mode until the watchdog
+	 * daemon takes control
+	 */
+	if (win_mode && wdat->boot_mode) {
+		regmap_read(wdat->regmap, DMEC_WDT_S1CFG, &val);
+		if (!(val & DMEC_WDT_WDSTS))
+			return 0;
+		val |= DMEC_WDT_WDSTS;
+		regmap_write(wdat->regmap, DMEC_WDT_S1CFG, val);
+	}
+
+	regmap_write(wdat->regmap, DMEC_WDT_SRV, 0xff);
+
+	return 0;
+}
+
+static int dmec_wdt_set_win_mode(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+
+	regmap_update_bits(wdat->regmap, DMEC_WDT_CFG,
+			   DMEC_WDT_WIN_MODE, DMEC_WDT_WIN_MODE);
+
+	return 0;
+}
+
+static int dmec_wdt_set_std_mode(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+
+	regmap_update_bits(wdat->regmap, DMEC_WDT_CFG, DMEC_WDT_WIN_MODE, 0);
+
+	return 0;
+}
+
+static int dmec_wdt_set_timeout(struct watchdog_device *wdd,
+				unsigned int timeout)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+
+	wdd->timeout = timeout;
+	wdat->boot_mode = false;
+	dmec_wdt_stop(wdd);
+	dmec_wdt_clear_action(wdat, S0);
+
+	if (win_mode) {
+		dmec_wdt_clear_action(wdat, S1);
+		dmec_wdt_set_stage_timeout(wdat, S1, wdat->s1_time);
+		dmec_wdt_set_stage_action(wdat, S1, WDT_DELAY);
+		dmec_wdt_set_win_mode(wdd);
+	} else {
+		dmec_wdt_set_std_mode(wdd);
+	}
+
+	wdat->s2_time = timeout;
+	dmec_wdt_clear_action(wdat, S2);
+	dmec_wdt_set_stage_timeout(wdat, S2, timeout);
+	dmec_wdt_set_stage_action(wdat, S2, WDT_RESET);
+	clear_bit(WDOG_HW_RUNNING, &wdd->status);
+	dmec_wdt_start(wdd);
+
+	return 0;
+}
+
+static long dmec_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
+			   unsigned long arg)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+	void __user *argp = (void __user *)arg;
+	int ret = -ENOIOCTLCMD;
+	int __user *p = argp;
+	int val;
+
+	switch (cmd) {
+	case WDIOC_SETPRETIMEOUT:
+		if (get_user(val, p) && val < 0)
+			return -EFAULT;
+		dmec_wdt_clear_action(wdat, S1);
+		if (val > 0) {
+			dmec_wdt_set_stage_timeout(wdat, S1, val);
+			dmec_wdt_set_stage_action(wdat, S1, action);
+		}
+		wdat->s1_time = val;
+		wdat->boot_mode = false;
+		ret = 0;
+		if (!win_mode)
+			ret = dmec_wdt_ping(wdd);
+		break;
+	case WDIOC_GETPRETIMEOUT:
+		ret = put_user(wdat->s1_time, (int __user *)arg);
+		break;
+	}
+
+	return ret;
+}
+
+static unsigned int dmec_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+
+	return dmec_wdt_get_stage_timeout(wdat, 2);
+}
+
+static unsigned int dmec_wdt_status(struct watchdog_device *wdd)
+{
+	struct dmec_wdt_data *wdat = watchdog_get_drvdata(wdd);
+	unsigned int status;
+
+	regmap_read(wdat->regmap, DMEC_WDT_CFG, &status);
+
+	return status;
+}
+
+static struct watchdog_info dmec_wdt_info = {
+	.options		= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+				  WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT,
+	.identity		= "DMEC WDT",
+};
+
+static const struct watchdog_ops dmec_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= dmec_wdt_start,
+	.stop		= dmec_wdt_stop,
+	.ping		= dmec_wdt_ping,
+	.set_timeout	= dmec_wdt_set_timeout,
+	.status		= dmec_wdt_status,
+	.ioctl		= dmec_wdt_ioctl,
+	.get_timeleft	= dmec_wdt_get_timeleft,
+};
+
+static int dmec_wdt_get_hw_ping_time(struct dmec_wdt_data *wdat)
+{
+	struct watchdog_device *wdd = &wdat->wdd;
+	unsigned int val, t;
+
+	regmap_read(wdat->regmap, DMEC_WDT_S0CFG, &val);
+	t = dmec_wdt_get_stage_timeout(wdat, S0);
+	if (t && (val & 0x7) > 1)
+		dmec_wdt_clear_action(wdat, S0);
+
+	wdat->s1_time = dmec_wdt_get_stage_timeout(wdat, S1);
+	wdat->s2_time = dmec_wdt_get_stage_timeout(wdat, S2);
+
+	regmap_read(wdat->regmap, DMEC_WDT_S1CFG, &val);
+	if (wdat->s1_time && (val & 0x7) > 1 && !(val & DMEC_WDT_WDSTS)) {
+		wdd->timeout = wdat->s1_time;
+		return 1;
+	}
+
+	regmap_read(wdat->regmap, DMEC_WDT_S2CFG, &val);
+	if (wdat->s2_time && (val & 0x7) > 1 && !(val & DMEC_WDT_WDSTS)) {
+		wdd->timeout = wdat->s2_time;
+		return 2;
+	}
+
+	return -1;
+}
+
+static int dmec_wdt_config_win_mode(struct dmec_wdt_data *wdat)
+{
+	struct watchdog_device *wdd = &wdat->wdd;
+	unsigned int t;
+
+	/* The timeout should be ok until the watchdog daemon appears */
+	t = (min_t(unsigned int, wdat->s1_time, wdat->s2_time) / 2);
+	wdd->timeout = t;
+
+	return 0;
+}
+
+static int dmec_wdt_config_mode(struct dmec_wdt_data *wdat)
+{
+	struct watchdog_device *wdd = &wdat->wdd;
+
+	if (!(wdat->boot_cfg & DMEC_WDT_EN))
+		return -1;
+
+	if (dmec_wdt_get_hw_ping_time(wdat) < 0)
+		return -1;
+
+	wdd->max_hw_heartbeat_ms = DMEC_WDT_TIMEOUT_MAX * 1000;
+	set_bit(WDOG_HW_RUNNING, &wdd->status);
+
+	if (wdat->boot_cfg & DMEC_WDT_WIN_MODE)
+		dmec_wdt_config_win_mode(wdat);
+
+	wdat->boot_mode = true;
+
+	return 0;
+}
+
+static int dmec_wdt_setup(struct dmec_wdt_data *wdat)
+{
+	struct watchdog_device *wdd = &wdat->wdd;
+	int ret = 0;
+
+	regmap_read(wdat->regmap, DMEC_WDT_CFG, &wdat->boot_cfg);
+
+	ret = dmec_wdt_config_mode(wdat);
+
+	if (ret < 0)
+		dmec_wdt_set_timeouts(wdat);
+
+	if (wdat->boot_cfg & DMEC_WDT_LOCK && !nowayout) {
+		dev_info(wdd->parent, "watchdog lock is enabled.\n");
+		nowayout = true;
+		return 0;
+	}
+
+	return 0;
+}
+
+static int dmec_wdt_probe(struct platform_device *pdev)
+{
+	struct dmec_wdt_data *wdat;
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	int ret = 0;
+
+	wdat = devm_kzalloc(dev, sizeof(*wdat), GFP_KERNEL);
+	if (!wdat)
+		return -ENOMEM;
+
+	wdat->regmap = dmec_get_regmap(pdev->dev.parent);
+	wdd = &wdat->wdd;
+	wdd->parent = dev;
+
+	wdd->info = &dmec_wdt_info;
+	wdd->ops = &dmec_wdt_ops;
+	wdd->min_timeout = DMEC_WDT_TIMEOUT_MIN;
+	wdd->max_timeout = DMEC_WDT_TIMEOUT_MAX;
+
+	wdat->s1_time = s1_timeout;
+	wdat->s2_time = s2_timeout;
+
+	watchdog_set_drvdata(wdd, wdat);
+	platform_set_drvdata(pdev, wdat);
+
+	dmec_wdt_setup(wdat);
+
+	watchdog_set_nowayout(wdd, nowayout);
+	if (stop_on_reboot)
+		watchdog_stop_on_reboot(wdd);
+
+	ret = watchdog_register_device(wdd);
+	if (ret)
+		return ret;
+
+	regmap_read(wdat->regmap, DMEC_WDT_VER,
+		    &dmec_wdt_info.firmware_version);
+
+	dev_info(dev, "registered. v%u.%u sta: %#lx mode:%d\n",
+		 (dmec_wdt_info.firmware_version >> 4) & 0xf,
+		 dmec_wdt_info.firmware_version & 0xf,
+		 wdd->status, win_mode);
+
+	return 0;
+}
+
+static int dmec_wdt_remove(struct platform_device *pdev)
+{
+	struct dmec_wdt_data *wdat = platform_get_drvdata(pdev);
+
+	dmec_wdt_stop(&wdat->wdd);
+	watchdog_unregister_device(&wdat->wdd);
+
+	return 0;
+}
+
+static void dmec_wdt_shutdown(struct platform_device *pdev)
+{
+	struct dmec_wdt_data *wdat = platform_get_drvdata(pdev);
+
+	dmec_wdt_stop(&wdat->wdd);
+}
+
+#ifdef CONFIG_PM
+/* Disable watchdog if it is active during suspend */
+static int dmec_wdt_suspend(struct platform_device *pdev,
+			    pm_message_t message)
+{
+	struct dmec_wdt_data *wdat = platform_get_drvdata(pdev);
+	struct watchdog_device *wdd = &wdat->wdd;
+
+	regmap_read(wdat->regmap, DMEC_WDT_CFG, &wdat->status);
+
+	if (wdat->status & DMEC_WDT_EN)
+		return dmec_wdt_stop(wdd);
+
+	return 0;
+}
+
+/* Enable watchdog and configure it if necessary */
+static int dmec_wdt_resume(struct platform_device *pdev)
+{
+	struct dmec_wdt_data *wdat = platform_get_drvdata(pdev);
+	struct watchdog_device *wdd = &wdat->wdd;
+
+	if (!win_mode && wdat->status & DMEC_WDT_EN) {
+		dmec_wdt_stop(wdd);
+		dmec_wdt_clear_action(wdat, S0);
+		dmec_wdt_clear_action(wdat, S1);
+		dmec_wdt_clear_action(wdat, S2);
+
+		if (wdat->s1_time) {
+			dmec_wdt_set_stage_timeout(wdat, S1, wdat->s1_time);
+			dmec_wdt_set_stage_action(wdat, S1, WDT_DELAY);
+		}
+		dmec_wdt_set_stage_timeout(wdat, S2, wdat->s2_time);
+		dmec_wdt_set_stage_action(wdat, S2, WDT_RESET);
+		dmec_wdt_get_timeleft(wdd);
+		return dmec_wdt_start(wdd);
+	}
+
+	return dmec_wdt_stop(wdd);
+}
+#else
+#define dmec_wdt_suspend NULL
+#define dmec_wdt_resume	NULL
+#endif
+
+static struct platform_driver dmec_wdt_driver = {
+	.driver = {
+		.name = "dmec-wdt",
+		.owner = THIS_MODULE,
+	},
+	.probe = dmec_wdt_probe,
+	.remove = dmec_wdt_remove,
+	.shutdown = dmec_wdt_shutdown,
+	.suspend = dmec_wdt_suspend,
+	.resume = dmec_wdt_resume,
+};
+
+module_platform_driver(dmec_wdt_driver);
+
+MODULE_DESCRIPTION("dmec watchdog driver");
+MODULE_AUTHOR("Zahari Doychev <zahari.doychev@linux.com");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:dmec-wdt");