watchdog: Kontron PLD watchdog timer driver

Add watchdog timer support for the on-board PLD found on some Kontron
embedded modules.

Originally-From: Michael Brunner <michael.brunner@kontron.com>
Signed-off-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Acked-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

3 files changed, 593 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e89fc31..7460d34 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -687,6 +687,17 @@ config HP_WATCHDOG
 	  To compile this driver as a module, choose M here: the module will be
 	  called hpwdt.
 
+config KEMPLD_WDT
+	tristate "Kontron COM Watchdog Timer"
+	depends on MFD_KEMPLD
+	select WATCHDOG_CORE
+	help
+	  Support for the PLD watchdog on some Kontron ETX and COMexpress
+	  (ETXexpress) modules
+
+	  This driver can also be built as a module. If so, the module will be
+	  called kempld_wdt.
+
 config HPWDT_NMI_DECODING
 	bool "NMI decoding support for the HP ProLiant iLO2+ Hardware Watchdog Timer"
 	depends on HP_WATCHDOG
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a300b94..ec26899 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -90,6 +90,7 @@ endif
 obj-$(CONFIG_IT8712F_WDT) += it8712f_wdt.o
 obj-$(CONFIG_IT87_WDT) += it87_wdt.o
 obj-$(CONFIG_HP_WATCHDOG) += hpwdt.o
+obj-$(CONFIG_KEMPLD_WDT) += kempld_wdt.o
 obj-$(CONFIG_SC1200_WDT) += sc1200wdt.o
 obj-$(CONFIG_SCx200_WDT) += scx200_wdt.o
 obj-$(CONFIG_PC87413_WDT) += pc87413_wdt.o
diff --git a/drivers/watchdog/kempld_wdt.c b/drivers/watchdog/kempld_wdt.c
new file mode 100644
index 0000000..491419e
--- /dev/null
+++ b/drivers/watchdog/kempld_wdt.c
@@ -0,0 +1,581 @@
+/*
+ * Kontron PLD watchdog driver
+ *
+ * Copyright (c) 2010-2013 Kontron Europe GmbH
+ * Author: Michael Brunner <michael.brunner@kontron.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Note: From the PLD watchdog point of view timeout and pretimeout are
+ *       defined differently than in the kernel.
+ *       First the pretimeout stage runs out before the timeout stage gets
+ *       active.
+ *
+ * Kernel/API:                     P-----| pretimeout
+ *               |-----------------------T timeout
+ * Watchdog:     |-----------------P       pretimeout_stage
+ *                                 |-----T timeout_stage
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/kempld.h>
+
+#define KEMPLD_WDT_STAGE_TIMEOUT(x)	(0x1b + (x) * 4)
+#define KEMPLD_WDT_STAGE_CFG(x)		(0x18 + (x))
+#define STAGE_CFG_GET_PRESCALER(x)	(((x) & 0x30) >> 4)
+#define STAGE_CFG_SET_PRESCALER(x)	(((x) & 0x30) << 4)
+#define STAGE_CFG_PRESCALER_MASK	0x30
+#define STAGE_CFG_ACTION_MASK		0x7
+#define STAGE_CFG_ASSERT		(1 << 3)
+
+#define KEMPLD_WDT_MAX_STAGES		2
+#define KEMPLD_WDT_KICK			0x16
+#define KEMPLD_WDT_CFG			0x17
+#define KEMPLD_WDT_CFG_ENABLE		0x10
+#define KEMPLD_WDT_CFG_ENABLE_LOCK	0x8
+#define KEMPLD_WDT_CFG_GLOBAL_LOCK	0x80
+
+enum {
+	ACTION_NONE = 0,
+	ACTION_RESET,
+	ACTION_NMI,
+	ACTION_SMI,
+	ACTION_SCI,
+	ACTION_DELAY,
+};
+
+enum {
+	STAGE_TIMEOUT = 0,
+	STAGE_PRETIMEOUT,
+};
+
+enum {
+	PRESCALER_21 = 0,
+	PRESCALER_17,
+	PRESCALER_12,
+};
+
+const u32 kempld_prescaler[] = {
+	[PRESCALER_21] = (1 << 21) - 1,
+	[PRESCALER_17] = (1 << 17) - 1,
+	[PRESCALER_12] = (1 << 12) - 1,
+	0,
+};
+
+struct kempld_wdt_stage {
+	unsigned int	id;
+	u32		mask;
+};
+
+struct kempld_wdt_data {
+	struct kempld_device_data	*pld;
+	struct watchdog_device		wdd;
+	unsigned int			pretimeout;
+	struct kempld_wdt_stage		stage[KEMPLD_WDT_MAX_STAGES];
+#ifdef CONFIG_PM
+	u8				pm_status_store;
+#endif
+};
+
+#define DEFAULT_TIMEOUT		30 /* seconds */
+#define DEFAULT_PRETIMEOUT	0
+
+static unsigned int timeout = DEFAULT_TIMEOUT;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+	"Watchdog timeout in seconds. (>=0, default="
+	__MODULE_STRING(DEFAULT_TIMEOUT) ")");
+
+static unsigned int pretimeout = DEFAULT_PRETIMEOUT;
+module_param(pretimeout, uint, 0);
+MODULE_PARM_DESC(pretimeout,
+	"Watchdog pretimeout in seconds. (>=0, default="
+	__MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
+
+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) ")");
+
+static int kempld_wdt_set_stage_action(struct kempld_wdt_data *wdt_data,
+					struct kempld_wdt_stage *stage,
+					u8 action)
+{
+	struct kempld_device_data *pld = wdt_data->pld;
+	u8 stage_cfg;
+
+	if (!stage || !stage->mask)
+		return -EINVAL;
+
+	kempld_get_mutex(pld);
+	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
+	stage_cfg &= ~STAGE_CFG_ACTION_MASK;
+	stage_cfg |= (action & STAGE_CFG_ACTION_MASK);
+
+	if (action == ACTION_RESET)
+		stage_cfg |= STAGE_CFG_ASSERT;
+	else
+		stage_cfg &= ~STAGE_CFG_ASSERT;
+
+	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
+	kempld_release_mutex(pld);
+
+	return 0;
+}
+
+static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
+					struct kempld_wdt_stage *stage,
+					unsigned int timeout)
+{
+	struct kempld_device_data *pld = wdt_data->pld;
+	u32 prescaler = kempld_prescaler[PRESCALER_21];
+	u64 stage_timeout64;
+	u32 stage_timeout;
+	u32 remainder;
+	u8 stage_cfg;
+
+	if (!stage)
+		return -EINVAL;
+
+	stage_timeout64 = (u64)timeout * pld->pld_clock;
+	remainder = do_div(stage_timeout64, prescaler);
+	if (remainder)
+		stage_timeout64++;
+
+	if (stage_timeout64 > stage->mask)
+		return -EINVAL;
+
+	stage_timeout = stage_timeout64 & stage->mask;
+
+	kempld_get_mutex(pld);
+	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
+	stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
+	stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
+	kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
+	kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
+			stage_timeout);
+	kempld_release_mutex(pld);
+
+	return 0;
+}
+
+/*
+ * kempld_get_mutex must be called prior to calling this function.
+ */
+static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
+						struct kempld_wdt_stage *stage)
+{
+	struct kempld_device_data *pld = wdt_data->pld;
+	unsigned int timeout;
+	u64 stage_timeout;
+	u32 prescaler;
+	u32 remainder;
+	u8 stage_cfg;
+
+	if (!stage->mask)
+		return 0;
+
+	stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
+	stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
+	prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];
+
+	stage_timeout = (stage_timeout & stage->mask) * prescaler;
+	remainder = do_div(stage_timeout, pld->pld_clock);
+	if (remainder)
+		stage_timeout++;
+
+	timeout = stage_timeout;
+	WARN_ON_ONCE(timeout != stage_timeout);
+
+	return timeout;
+}
+
+static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
+					unsigned int timeout)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct kempld_wdt_stage *pretimeout_stage;
+	struct kempld_wdt_stage *timeout_stage;
+	int ret;
+
+	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
+	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+
+	if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
+		timeout = wdt_data->pretimeout;
+
+	ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
+						ACTION_RESET);
+	if (ret)
+		return ret;
+	ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
+						timeout);
+	if (ret)
+		return ret;
+
+	wdd->timeout = timeout;
+	return 0;
+}
+
+static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
+					unsigned int pretimeout)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct kempld_wdt_stage *pretimeout_stage;
+	u8 action = ACTION_NONE;
+	int ret;
+
+	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+
+	if (!pretimeout_stage->mask)
+		return -ENXIO;
+
+	if (pretimeout > wdd->timeout)
+		return -EINVAL;
+
+	if (pretimeout > 0)
+		action = ACTION_NMI;
+
+	ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
+						action);
+	if (ret)
+		return ret;
+	ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
+						wdd->timeout - pretimeout);
+	if (ret)
+		return ret;
+
+	wdt_data->pretimeout = pretimeout;
+	return 0;
+}
+
+static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
+{
+	struct kempld_device_data *pld = wdt_data->pld;
+	struct kempld_wdt_stage *pretimeout_stage;
+	struct kempld_wdt_stage *timeout_stage;
+	unsigned int pretimeout, timeout;
+
+	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
+
+	kempld_get_mutex(pld);
+	pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
+	timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
+	kempld_release_mutex(pld);
+
+	if (pretimeout)
+		wdt_data->pretimeout = timeout;
+	else
+		wdt_data->pretimeout = 0;
+
+	wdt_data->wdd.timeout = pretimeout + timeout;
+}
+
+static int kempld_wdt_start(struct watchdog_device *wdd)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct kempld_device_data *pld = wdt_data->pld;
+	u8 status;
+	int ret;
+
+	ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
+	if (ret)
+		return ret;
+
+	kempld_get_mutex(pld);
+	status = kempld_read8(pld, KEMPLD_WDT_CFG);
+	status |= KEMPLD_WDT_CFG_ENABLE;
+	kempld_write8(pld, KEMPLD_WDT_CFG, status);
+	status = kempld_read8(pld, KEMPLD_WDT_CFG);
+	kempld_release_mutex(pld);
+
+	/* Check if the watchdog was enabled */
+	if (!(status & KEMPLD_WDT_CFG_ENABLE))
+		return -EACCES;
+
+	return 0;
+}
+
+static int kempld_wdt_stop(struct watchdog_device *wdd)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct kempld_device_data *pld = wdt_data->pld;
+	u8 status;
+
+	kempld_get_mutex(pld);
+	status = kempld_read8(pld, KEMPLD_WDT_CFG);
+	status &= ~KEMPLD_WDT_CFG_ENABLE;
+	kempld_write8(pld, KEMPLD_WDT_CFG, status);
+	status = kempld_read8(pld, KEMPLD_WDT_CFG);
+	kempld_release_mutex(pld);
+
+	/* Check if the watchdog was disabled */
+	if (status & KEMPLD_WDT_CFG_ENABLE)
+		return -EACCES;
+
+	return 0;
+}
+
+static int kempld_wdt_keepalive(struct watchdog_device *wdd)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct kempld_device_data *pld = wdt_data->pld;
+
+	kempld_get_mutex(pld);
+	kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
+	kempld_release_mutex(pld);
+
+	return 0;
+}
+
+static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
+				unsigned long arg)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	void __user *argp = (void __user *)arg;
+	int ret = -ENOIOCTLCMD;
+	int __user *p = argp;
+	int new_value;
+
+	switch (cmd) {
+	case WDIOC_SETPRETIMEOUT:
+		if (get_user(new_value, p))
+			return -EFAULT;
+		ret = kempld_wdt_set_pretimeout(wdd, new_value);
+		if (ret)
+			return ret;
+		ret = kempld_wdt_keepalive(wdd);
+		break;
+	case WDIOC_GETPRETIMEOUT:
+		ret = put_user(wdt_data->pretimeout, (int *)arg);
+		break;
+	}
+
+	return ret;
+}
+
+static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
+{
+	struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct kempld_device_data *pld = wdt_data->pld;
+	struct kempld_wdt_stage *pretimeout_stage;
+	struct kempld_wdt_stage *timeout_stage;
+	u8 index, data, data_orig;
+	u32 mask;
+	int i, j;
+
+	pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+	timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
+
+	pretimeout_stage->mask = 0;
+	timeout_stage->mask = 0;
+
+	for (i = 0; i < 3; i++) {
+		index = KEMPLD_WDT_STAGE_TIMEOUT(i);
+		mask = 0;
+
+		kempld_get_mutex(pld);
+		/* Probe each byte individually. */
+		for (j = 0; j < 4; j++) {
+			data_orig = kempld_read8(pld, index + j);
+			kempld_write8(pld, index + j, 0x00);
+			data = kempld_read8(pld, index + j);
+			/* A failed write means this byte is reserved */
+			if (data != 0x00)
+				break;
+			kempld_write8(pld, index + j, data_orig);
+			mask |= 0xff << (j * 8);
+		}
+		kempld_release_mutex(pld);
+
+		/* Assign available stages to timeout and pretimeout */
+		if (!timeout_stage->mask) {
+			timeout_stage->mask = mask;
+			timeout_stage->id = i;
+		} else {
+			if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
+				pretimeout_stage->mask = timeout_stage->mask;
+				timeout_stage->mask = mask;
+				pretimeout_stage->id = timeout_stage->id;
+				timeout_stage->id = i;
+			}
+			break;
+		}
+	}
+
+	if (!timeout_stage->mask)
+		return -ENODEV;
+
+	return 0;
+}
+
+static struct watchdog_info kempld_wdt_info = {
+	.identity	= "KEMPLD Watchdog",
+	.options	= WDIOF_SETTIMEOUT |
+			WDIOF_KEEPALIVEPING |
+			WDIOF_MAGICCLOSE |
+			WDIOF_PRETIMEOUT
+};
+
+static struct watchdog_ops kempld_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= kempld_wdt_start,
+	.stop		= kempld_wdt_stop,
+	.ping		= kempld_wdt_keepalive,
+	.set_timeout	= kempld_wdt_set_timeout,
+	.ioctl		= kempld_wdt_ioctl,
+};
+
+static int kempld_wdt_probe(struct platform_device *pdev)
+{
+	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
+	struct kempld_wdt_data *wdt_data;
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	u8 status;
+	int ret = 0;
+
+	wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
+	if (!wdt_data)
+		return -ENOMEM;
+
+	wdt_data->pld = pld;
+	wdd = &wdt_data->wdd;
+	wdd->parent = dev;
+
+	kempld_get_mutex(pld);
+	status = kempld_read8(pld, KEMPLD_WDT_CFG);
+	kempld_release_mutex(pld);
+
+	/* Enable nowayout if watchdog is already locked */
+	if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK |
+			KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
+		if (!nowayout)
+			dev_warn(dev,
+				"Forcing nowayout - watchdog lock enabled!\n");
+		nowayout = true;
+	}
+
+	wdd->info = &kempld_wdt_info;
+	wdd->ops = &kempld_wdt_ops;
+
+	watchdog_set_drvdata(wdd, wdt_data);
+	watchdog_set_nowayout(wdd, nowayout);
+
+	ret = kempld_wdt_probe_stages(wdd);
+	if (ret)
+		return ret;
+
+	kempld_wdt_set_timeout(wdd, timeout);
+	kempld_wdt_set_pretimeout(wdd, pretimeout);
+
+	/* Check if watchdog is already enabled */
+	if (status & KEMPLD_WDT_CFG_ENABLE) {
+		/* Get current watchdog settings */
+		kempld_wdt_update_timeouts(wdt_data);
+		dev_info(dev, "Watchdog was already enabled\n");
+	}
+
+	platform_set_drvdata(pdev, wdt_data);
+	ret = watchdog_register_device(wdd);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);
+
+	return 0;
+}
+
+static void kempld_wdt_shutdown(struct platform_device *pdev)
+{
+	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+
+	kempld_wdt_stop(&wdt_data->wdd);
+}
+
+static int kempld_wdt_remove(struct platform_device *pdev)
+{
+	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+	struct watchdog_device *wdd = &wdt_data->wdd;
+	int ret = 0;
+
+	if (!nowayout)
+		ret = kempld_wdt_stop(wdd);
+	watchdog_unregister_device(wdd);
+
+	return ret;
+}
+
+#ifdef CONFIG_PM
+/* Disable watchdog if it is active during suspend */
+static int kempld_wdt_suspend(struct platform_device *pdev,
+				pm_message_t message)
+{
+	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+	struct kempld_device_data *pld = wdt_data->pld;
+	struct watchdog_device *wdd = &wdt_data->wdd;
+
+	kempld_get_mutex(pld);
+	wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
+	kempld_release_mutex(pld);
+
+	kempld_wdt_update_timeouts(wdt_data);
+
+	if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
+		return kempld_wdt_stop(wdd);
+
+	return 0;
+}
+
+/* Enable watchdog and configure it if necessary */
+static int kempld_wdt_resume(struct platform_device *pdev)
+{
+	struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+	struct watchdog_device *wdd = &wdt_data->wdd;
+
+	/*
+	 * If watchdog was stopped before suspend be sure it gets disabled
+	 * again, for the case BIOS has enabled it during resume
+	 */
+	if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
+		return kempld_wdt_start(wdd);
+	else
+		return kempld_wdt_stop(wdd);
+}
+#else
+#define kempld_wdt_suspend	NULL
+#define kempld_wdt_resume	NULL
+#endif
+
+static struct platform_driver kempld_wdt_driver = {
+	.driver		= {
+		.name	= "kempld-wdt",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= kempld_wdt_probe,
+	.remove		= kempld_wdt_remove,
+	.shutdown	= kempld_wdt_shutdown,
+	.suspend	= kempld_wdt_suspend,
+	.resume		= kempld_wdt_resume,
+};
+
+module_platform_driver(kempld_wdt_driver);
+
+MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
+MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);