watchdog: add ralink watchdog driver

Add a driver for the watchdog timer found on Ralink SoC
Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: devicetree-discuss@lists.ozlabs.org

Documentation/devicetree/bindings/watchdog/rt2880-wdt.txt

+Ralink Watchdog Timers
+
+Required properties:
+- compatible: must be "ralink,rt2880-wdt"
+- reg: physical base address of the controller and length of the register range
+
+Optional properties:
+- interrupt-parent: phandle to the INTC device node
+- interrupts: Specify the INTC interrupt number
+
+Example:
+
+	watchdog@120 {
+		compatible = "ralink,rt2880-wdt";
+		reg = <0x120 0x10>;
+
+		interrupt-parent = <&intc>;
+		interrupts = <1>;
+	};

drivers/watchdog/Kconfig

@@ -1135,6 +1135,13 @@ config LANTIQ_WDT
 	help
 	  Hardware driver for the Lantiq SoC Watchdog Timer.
 
+config RALINK_WDT
+	tristate "Ralink SoC watchdog"
+	select WATCHDOG_CORE
+	depends on RALINK
+	help
+	  Hardware driver for the Ralink SoC Watchdog Timer.
+
 # PARISC Architecture
 
 # POWERPC Architecture

drivers/watchdog/Makefile

@@ -135,6 +135,7 @@ obj-$(CONFIG_TXX9_WDT) += txx9wdt.o
 obj-$(CONFIG_OCTEON_WDT) += octeon-wdt.o
 octeon-wdt-y := octeon-wdt-main.o octeon-wdt-nmi.o
 obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o
+obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o
 
 # PARISC Architecture
 

drivers/watchdog/rt2880_wdt.c

+/*
+ * Ralink RT288x/RT3xxx/MT76xx built-in hardware watchdog timer
+ *
+ * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
+ *
+ * This driver was based on: drivers/watchdog/softdog.c
+ *
+ * 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/clk.h>
+#include <linux/reset.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/watchdog.h>
+#include <linux/miscdevice.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+
+#include <asm/mach-ralink/ralink_regs.h>
+
+#define SYSC_RSTSTAT			0x38
+#define WDT_RST_CAUSE			BIT(1)
+
+#define RALINK_WDT_TIMEOUT		30
+#define RALINK_WDT_PRESCALE		65536
+
+#define TIMER_REG_TMR1LOAD		0x00
+#define TIMER_REG_TMR1CTL		0x08
+
+#define TMRSTAT_TMR1RST			BIT(5)
+
+#define TMR1CTL_ENABLE			BIT(7)
+#define TMR1CTL_MODE_SHIFT		4
+#define TMR1CTL_MODE_MASK		0x3
+#define TMR1CTL_MODE_FREE_RUNNING	0x0
+#define TMR1CTL_MODE_PERIODIC		0x1
+#define TMR1CTL_MODE_TIMEOUT		0x2
+#define TMR1CTL_MODE_WDT		0x3
+#define TMR1CTL_PRESCALE_MASK		0xf
+#define TMR1CTL_PRESCALE_65536		0xf
+
+static struct clk *rt288x_wdt_clk;
+static unsigned long rt288x_wdt_freq;
+static void __iomem *rt288x_wdt_base;
+
+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 inline void rt_wdt_w32(unsigned reg, u32 val)
+{
+	iowrite32(val, rt288x_wdt_base + reg);
+}
+
+static inline u32 rt_wdt_r32(unsigned reg)
+{
+	return ioread32(rt288x_wdt_base + reg);
+}
+
+static int rt288x_wdt_ping(struct watchdog_device *w)
+{
+	rt_wdt_w32(TIMER_REG_TMR1LOAD, w->timeout * rt288x_wdt_freq);
+
+	return 0;
+}
+
+static int rt288x_wdt_start(struct watchdog_device *w)
+{
+	u32 t;
+
+	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
+	t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
+		TMR1CTL_PRESCALE_MASK);
+	t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
+		TMR1CTL_PRESCALE_65536);
+	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
+
+	rt288x_wdt_ping(w);
+
+	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
+	t |= TMR1CTL_ENABLE;
+	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
+
+	return 0;
+}
+
+static int rt288x_wdt_stop(struct watchdog_device *w)
+{
+	u32 t;
+
+	rt288x_wdt_ping(w);
+
+	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
+	t &= ~TMR1CTL_ENABLE;
+	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
+
+	return 0;
+}
+
+static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
+{
+	w->timeout = t;
+	rt288x_wdt_ping(w);
+
+	return 0;
+}
+
+static int rt288x_wdt_bootcause(void)
+{
+	if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
+		return WDIOF_CARDRESET;
+
+	return 0;
+}
+
+static struct watchdog_info rt288x_wdt_info = {
+	.identity = "Ralink Watchdog",
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+};
+
+static struct watchdog_ops rt288x_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = rt288x_wdt_start,
+	.stop = rt288x_wdt_stop,
+	.ping = rt288x_wdt_ping,
+	.set_timeout = rt288x_wdt_set_timeout,
+};
+
+static struct watchdog_device rt288x_wdt_dev = {
+	.info = &rt288x_wdt_info,
+	.ops = &rt288x_wdt_ops,
+	.min_timeout = 1,
+};
+
+static int rt288x_wdt_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rt288x_wdt_base = devm_request_and_ioremap(&pdev->dev, res);
+	if (IS_ERR(rt288x_wdt_base))
+		return PTR_ERR(rt288x_wdt_base);
+
+	rt288x_wdt_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(rt288x_wdt_clk))
+		return PTR_ERR(rt288x_wdt_clk);
+
+	device_reset(&pdev->dev);
+
+	rt288x_wdt_freq = clk_get_rate(rt288x_wdt_clk) / RALINK_WDT_PRESCALE;
+
+	rt288x_wdt_dev.dev = &pdev->dev;
+	rt288x_wdt_dev.bootstatus = rt288x_wdt_bootcause();
+
+	rt288x_wdt_dev.max_timeout = (0xfffful / rt288x_wdt_freq);
+	rt288x_wdt_dev.timeout = rt288x_wdt_dev.max_timeout;
+
+	watchdog_set_nowayout(&rt288x_wdt_dev, nowayout);
+
+	ret = watchdog_register_device(&rt288x_wdt_dev);
+	if (!ret)
+		dev_info(&pdev->dev, "Initialized\n");
+
+	return 0;
+}
+
+static int rt288x_wdt_remove(struct platform_device *pdev)
+{
+	watchdog_unregister_device(&rt288x_wdt_dev);
+
+	return 0;
+}
+
+static void rt288x_wdt_shutdown(struct platform_device *pdev)
+{
+	rt288x_wdt_stop(&rt288x_wdt_dev);
+}
+
+static const struct of_device_id rt288x_wdt_match[] = {
+	{ .compatible = "ralink,rt2880-wdt" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
+
+static struct platform_driver rt288x_wdt_driver = {
+	.probe		= rt288x_wdt_probe,
+	.remove		= rt288x_wdt_remove,
+	.shutdown	= rt288x_wdt_shutdown,
+	.driver		= {
+		.name		= KBUILD_MODNAME,
+		.owner		= THIS_MODULE,
+		.of_match_table	= rt288x_wdt_match,
+	},
+};
+
+module_platform_driver(rt288x_wdt_driver);
+
+MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);