watchdog: add support for Sigma Designs SMP86xx/SMP87xx

This adds support for the Sigma Designs SMP86xx/SMP87xx family built-in
watchdog.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -142,6 +142,16 @@ config MENF21BMC_WATCHDOG
 	  This driver can also be built as a module. If so the module
 	  will be called menf21bmc_wdt.
 
+config TANGOX_WATCHDOG
+	tristate "Sigma Designs SMP86xx/SMP87xx watchdog"
+	select WATCHDOG_CORE
+	depends on ARCH_TANGOX || COMPILE_TEST
+	help
+	  Support for the watchdog in Sigma Designs SMP86xx (tango3)
+	  and SMP87xx (tango4) family chips.
+
+	  This driver can be built as a module. The module name is tangox_wdt.
+
 config WM831X_WATCHDOG
 	tristate "WM831x watchdog"
 	depends on MFD_WM831X

drivers/watchdog/Makefile

@@ -190,6 +190,7 @@ obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
 obj-$(CONFIG_DA9062_WATCHDOG) += da9062_wdt.o
 obj-$(CONFIG_DA9063_WATCHDOG) += da9063_wdt.o
 obj-$(CONFIG_GPIO_WATCHDOG)	+= gpio_wdt.o
+obj-$(CONFIG_TANGOX_WATCHDOG) += tangox_wdt.o
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
 obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o

drivers/watchdog/tangox_wdt.c

@@ -0,0 +1,225 @@
+/*
+ *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
+ *  SMP86xx/SMP87xx Watchdog driver
+ *
+ *  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/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+#define DEFAULT_TIMEOUT 30
+
+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 unsigned int timeout;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout");
+
+/*
+ * Counter counts down from programmed value.  Reset asserts when
+ * the counter reaches 1.
+ */
+#define WD_COUNTER		0
+
+#define WD_CONFIG		4
+#define WD_CONFIG_XTAL_IN	BIT(0)
+#define WD_CONFIG_DISABLE	BIT(31)
+
+struct tangox_wdt_device {
+	struct watchdog_device wdt;
+	void __iomem *base;
+	unsigned long clk_rate;
+	struct clk *clk;
+	struct notifier_block restart;
+};
+
+static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
+				  unsigned int new_timeout)
+{
+	wdt->timeout = new_timeout;
+
+	return 0;
+}
+
+static int tangox_wdt_start(struct watchdog_device *wdt)
+{
+	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
+	u32 ticks;
+
+	ticks = 1 + wdt->timeout * dev->clk_rate;
+	writel(ticks, dev->base + WD_COUNTER);
+
+	return 0;
+}
+
+static int tangox_wdt_stop(struct watchdog_device *wdt)
+{
+	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
+
+	writel(0, dev->base + WD_COUNTER);
+
+	return 0;
+}
+
+static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
+{
+	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
+	u32 count;
+
+	count = readl(dev->base + WD_COUNTER);
+
+	if (!count)
+		return 0;
+
+	return (count - 1) / dev->clk_rate;
+}
+
+static const struct watchdog_info tangox_wdt_info = {
+	.options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "tangox watchdog",
+};
+
+static const struct watchdog_ops tangox_wdt_ops = {
+	.start		= tangox_wdt_start,
+	.stop		= tangox_wdt_stop,
+	.set_timeout	= tangox_wdt_set_timeout,
+	.get_timeleft	= tangox_wdt_get_timeleft,
+};
+
+static int tangox_wdt_restart(struct notifier_block *nb, unsigned long action,
+			      void *data)
+{
+	struct tangox_wdt_device *dev =
+		container_of(nb, struct tangox_wdt_device, restart);
+
+	writel(1, dev->base + WD_COUNTER);
+
+	return NOTIFY_DONE;
+}
+
+static int tangox_wdt_probe(struct platform_device *pdev)
+{
+	struct tangox_wdt_device *dev;
+	struct resource *res;
+	u32 config;
+	int err;
+
+	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dev->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dev->base))
+		return PTR_ERR(dev->base);
+
+	dev->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dev->clk))
+		return PTR_ERR(dev->clk);
+
+	err = clk_prepare_enable(dev->clk);
+	if (err)
+		return err;
+
+	dev->clk_rate = clk_get_rate(dev->clk);
+
+	dev->wdt.parent = &pdev->dev;
+	dev->wdt.info = &tangox_wdt_info;
+	dev->wdt.ops = &tangox_wdt_ops;
+	dev->wdt.timeout = DEFAULT_TIMEOUT;
+	dev->wdt.min_timeout = 1;
+	dev->wdt.max_timeout = (U32_MAX - 1) / dev->clk_rate;
+
+	watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
+	watchdog_set_nowayout(&dev->wdt, nowayout);
+	watchdog_set_drvdata(&dev->wdt, dev);
+
+	/*
+	 * Deactivate counter if disable bit is set to avoid
+	 * accidental reset.
+	 */
+	config = readl(dev->base + WD_CONFIG);
+	if (config & WD_CONFIG_DISABLE)
+		writel(0, dev->base + WD_COUNTER);
+
+	writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
+
+	/*
+	 * Mark as active and restart with configured timeout if
+	 * already running.
+	 */
+	if (readl(dev->base + WD_COUNTER)) {
+		set_bit(WDOG_ACTIVE, &dev->wdt.status);
+		tangox_wdt_start(&dev->wdt);
+	}
+
+	err = watchdog_register_device(&dev->wdt);
+	if (err) {
+		clk_disable_unprepare(dev->clk);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, dev);
+
+	dev->restart.notifier_call = tangox_wdt_restart;
+	dev->restart.priority = 128;
+	err = register_restart_handler(&dev->restart);
+	if (err)
+		dev_warn(&pdev->dev, "failed to register restart handler\n");
+
+	dev_info(dev->wdt.dev, "SMP86xx/SMP87xx watchdog registered\n");
+
+	return 0;
+}
+
+static int tangox_wdt_remove(struct platform_device *pdev)
+{
+	struct tangox_wdt_device *dev = platform_get_drvdata(pdev);
+
+	tangox_wdt_stop(&dev->wdt);
+	clk_disable_unprepare(dev->clk);
+
+	unregister_restart_handler(&dev->restart);
+	watchdog_unregister_device(&dev->wdt);
+
+	return 0;
+}
+
+static const struct of_device_id tangox_wdt_dt_ids[] = {
+	{ .compatible = "sigma,smp8642-wdt" },
+	{ .compatible = "sigma,smp8759-wdt" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
+
+static struct platform_driver tangox_wdt_driver = {
+	.probe	= tangox_wdt_probe,
+	.remove	= tangox_wdt_remove,
+	.driver	= {
+		.name		= "tangox-wdt",
+		.of_match_table	= tangox_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(tangox_wdt_driver);
+
+MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
+MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
+MODULE_LICENSE("GPL");