watchdog: introduce retu_wdt driver

Introduce Retu watchdog driver.

Cc: linux-watchdog@vger.kernel.org
Acked-by: Felipe Balbi <balbi@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -377,6 +377,18 @@ config UX500_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called ux500_wdt.
 
+config RETU_WATCHDOG
+	tristate "Retu watchdog"
+	depends on MFD_RETU
+	select WATCHDOG_CORE
+	help
+	  Retu watchdog driver for Nokia Internet Tablets (770, N800,
+	  N810). At least on N800 the watchdog cannot be disabled, so
+	  this driver is essential and you should enable it.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called retu_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

@@ -53,6 +53,7 @@ obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
 obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
 obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
 obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
+obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/retu_wdt.c

@@ -0,0 +1,178 @@
+/*
+ * Retu watchdog driver
+ *
+ * Copyright (C) 2004, 2005 Nokia Corporation
+ *
+ * Based on code written by Amit Kucheria and Michael Buesch.
+ * Rewritten by Aaro Koskinen.
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * 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.
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/retu.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+
+/* Watchdog timer values in seconds */
+#define RETU_WDT_MAX_TIMER	63
+
+struct retu_wdt_dev {
+	struct retu_dev		*rdev;
+	struct device		*dev;
+	struct delayed_work	ping_work;
+};
+
+/*
+ * Since Retu watchdog cannot be disabled in hardware, we must kick it
+ * with a timer until userspace watchdog software takes over. If
+ * CONFIG_WATCHDOG_NOWAYOUT is set, we never start the feeding.
+ */
+static void retu_wdt_ping_enable(struct retu_wdt_dev *wdev)
+{
+	retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
+	schedule_delayed_work(&wdev->ping_work,
+			round_jiffies_relative(RETU_WDT_MAX_TIMER * HZ / 2));
+}
+
+static void retu_wdt_ping_disable(struct retu_wdt_dev *wdev)
+{
+	retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
+	cancel_delayed_work_sync(&wdev->ping_work);
+}
+
+static void retu_wdt_ping_work(struct work_struct *work)
+{
+	struct retu_wdt_dev *wdev = container_of(to_delayed_work(work),
+						struct retu_wdt_dev, ping_work);
+	retu_wdt_ping_enable(wdev);
+}
+
+static int retu_wdt_start(struct watchdog_device *wdog)
+{
+	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
+
+	retu_wdt_ping_disable(wdev);
+
+	return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
+}
+
+static int retu_wdt_stop(struct watchdog_device *wdog)
+{
+	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
+
+	retu_wdt_ping_enable(wdev);
+
+	return 0;
+}
+
+static int retu_wdt_ping(struct watchdog_device *wdog)
+{
+	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
+
+	return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
+}
+
+static int retu_wdt_set_timeout(struct watchdog_device *wdog,
+				unsigned int timeout)
+{
+	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
+
+	wdog->timeout = timeout;
+	return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
+}
+
+static const struct watchdog_info retu_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+	.identity = "Retu watchdog",
+};
+
+static const struct watchdog_ops retu_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= retu_wdt_start,
+	.stop		= retu_wdt_stop,
+	.ping		= retu_wdt_ping,
+	.set_timeout	= retu_wdt_set_timeout,
+};
+
+static int retu_wdt_probe(struct platform_device *pdev)
+{
+	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
+	bool nowayout = WATCHDOG_NOWAYOUT;
+	struct watchdog_device *retu_wdt;
+	struct retu_wdt_dev *wdev;
+	int ret;
+
+	retu_wdt = devm_kzalloc(&pdev->dev, sizeof(*retu_wdt), GFP_KERNEL);
+	if (!retu_wdt)
+		return -ENOMEM;
+
+	wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
+	if (!wdev)
+		return -ENOMEM;
+
+	retu_wdt->info		= &retu_wdt_info;
+	retu_wdt->ops		= &retu_wdt_ops;
+	retu_wdt->timeout	= RETU_WDT_MAX_TIMER;
+	retu_wdt->min_timeout	= 0;
+	retu_wdt->max_timeout	= RETU_WDT_MAX_TIMER;
+
+	watchdog_set_drvdata(retu_wdt, wdev);
+	watchdog_set_nowayout(retu_wdt, nowayout);
+
+	wdev->rdev		= rdev;
+	wdev->dev		= &pdev->dev;
+
+	INIT_DELAYED_WORK(&wdev->ping_work, retu_wdt_ping_work);
+
+	ret = watchdog_register_device(retu_wdt);
+	if (ret < 0)
+		return ret;
+
+	if (nowayout)
+		retu_wdt_ping(retu_wdt);
+	else
+		retu_wdt_ping_enable(wdev);
+
+	platform_set_drvdata(pdev, retu_wdt);
+
+	return 0;
+}
+
+static int retu_wdt_remove(struct platform_device *pdev)
+{
+	struct watchdog_device *wdog = platform_get_drvdata(pdev);
+	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
+
+	watchdog_unregister_device(wdog);
+	cancel_delayed_work_sync(&wdev->ping_work);
+
+	return 0;
+}
+
+static struct platform_driver retu_wdt_driver = {
+	.probe		= retu_wdt_probe,
+	.remove		= retu_wdt_remove,
+	.driver		= {
+		.name	= "retu-wdt",
+	},
+};
+module_platform_driver(retu_wdt_driver);
+
+MODULE_ALIAS("platform:retu-wdt");
+MODULE_DESCRIPTION("Retu watchdog");
+MODULE_AUTHOR("Amit Kucheria");
+MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
+MODULE_LICENSE("GPL");