watchdog: sirf: add watchdog driver of CSR SiRFprimaII and SiRFatlasVI

On CSR SiRFprimaII and SiRFatlasVI, the 6th timer can act as a watchdog
timer when the Watchdog mode is enabled.

watchdog occur when TIMER watchdog counter matches the value software
pre-set, when this event occurs, the effect is the same as the system
software reset.

Signed-off-by: Xianglong Du <[e-mail]>
Signed-off-by: Barry Song <[e-mail]>
Cc: Romain Izard <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

Documentation/devicetree/bindings/watchdog/sirfsoc_wdt.txt

···
+SiRFSoC Timer and Watchdog Timer(WDT) Controller
+
+Required properties:
+- compatible: "sirf,prima2-tick"
+- reg: Address range of tick timer/WDT register set
+- interrupts: interrupt number to the cpu
+
+Example:
+
+timer@b0020000 {
+	compatible = "sirf,prima2-tick";
+	reg = <0xb0020000 0x1000>;
+	interrupts = <0>;
+};

arch/arm/configs/prima2_defconfig

···
 CONFIG_SPI_SIRF=y
 CONFIG_SPI_SPIDEV=y
 # CONFIG_HWMON is not set
+CONFIG_WATCHDOG=y
 CONFIG_USB_GADGET=y
 CONFIG_USB_MASS_STORAGE=m
 CONFIG_MMC=y

drivers/watchdog/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called moxart_wdt.
 
+config SIRFSOC_WATCHDOG
+	tristate "SiRFSOC watchdog"
+	depends on ARCH_SIRF
+	select WATCHDOG_CORE
+	default y
+	help
+	  Support for CSR SiRFprimaII and SiRFatlasVI watchdog. When
+	  the watchdog triggers the system will be reset.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

···
 obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
 obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o
 obj-$(CONFIG_MOXART_WDT) += moxart_wdt.o
+obj-$(CONFIG_SIRFSOC_WATCHDOG) += sirfsoc_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/sirfsoc_wdt.c

···
+/*
+ * Watchdog driver for CSR SiRFprimaII and SiRFatlasVI
+ *
+ * Copyright (c) 2013 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/moduleparam.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#define SIRFSOC_TIMER_COUNTER_LO	0x0000
+#define SIRFSOC_TIMER_MATCH_0		0x0008
+#define SIRFSOC_TIMER_INT_EN		0x0024
+#define SIRFSOC_TIMER_WATCHDOG_EN	0x0028
+#define SIRFSOC_TIMER_LATCH		0x0030
+#define SIRFSOC_TIMER_LATCHED_LO	0x0034
+
+#define SIRFSOC_TIMER_WDT_INDEX		5
+
+#define SIRFSOC_WDT_MIN_TIMEOUT		30		/* 30 secs */
+#define SIRFSOC_WDT_MAX_TIMEOUT		(10 * 60)	/* 10 mins */
+#define SIRFSOC_WDT_DEFAULT_TIMEOUT	30		/* 30 secs */
+
+static unsigned int timeout = SIRFSOC_WDT_DEFAULT_TIMEOUT;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(timeout, uint, 0);
+module_param(nowayout, bool, 0);
+
+MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static unsigned int sirfsoc_wdt_gettimeleft(struct watchdog_device *wdd)
+{
+	u32 counter, match;
+	void __iomem *wdt_base;
+	int time_left;
+
+	wdt_base = watchdog_get_drvdata(wdd);
+	counter = readl(wdt_base + SIRFSOC_TIMER_COUNTER_LO);
+	match = readl(wdt_base +
+		SIRFSOC_TIMER_MATCH_0 + (SIRFSOC_TIMER_WDT_INDEX << 2));
+
+	time_left = match - counter;
+
+	return time_left / CLOCK_TICK_RATE;
+}
+
+static int sirfsoc_wdt_updatetimeout(struct watchdog_device *wdd)
+{
+	u32 counter, timeout_ticks;
+	void __iomem *wdt_base;
+
+	timeout_ticks = wdd->timeout * CLOCK_TICK_RATE;
+	wdt_base = watchdog_get_drvdata(wdd);
+
+	/* Enable the latch before reading the LATCH_LO register */
+	writel(1, wdt_base + SIRFSOC_TIMER_LATCH);
+
+	/* Set the TO value */
+	counter = readl(wdt_base + SIRFSOC_TIMER_LATCHED_LO);
+
+	counter += timeout_ticks;
+
+	writel(counter, wdt_base +
+		SIRFSOC_TIMER_MATCH_0 + (SIRFSOC_TIMER_WDT_INDEX << 2));
+
+	return 0;
+}
+
+static int sirfsoc_wdt_enable(struct watchdog_device *wdd)
+{
+	void __iomem *wdt_base = watchdog_get_drvdata(wdd);
+	sirfsoc_wdt_updatetimeout(wdd);
+
+	/*
+	 * NOTE: If interrupt is not enabled
+	 * then WD-Reset doesn't get generated at all.
+	 */
+	writel(readl(wdt_base + SIRFSOC_TIMER_INT_EN)
+		| (1 << SIRFSOC_TIMER_WDT_INDEX),
+		wdt_base + SIRFSOC_TIMER_INT_EN);
+	writel(1, wdt_base + SIRFSOC_TIMER_WATCHDOG_EN);
+
+	return 0;
+}
+
+static int sirfsoc_wdt_disable(struct watchdog_device *wdd)
+{
+	void __iomem *wdt_base = watchdog_get_drvdata(wdd);
+
+	writel(0, wdt_base + SIRFSOC_TIMER_WATCHDOG_EN);
+	writel(readl(wdt_base + SIRFSOC_TIMER_INT_EN)
+		& (~(1 << SIRFSOC_TIMER_WDT_INDEX)),
+		wdt_base + SIRFSOC_TIMER_INT_EN);
+
+	return 0;
+}
+
+static int sirfsoc_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
+{
+	wdd->timeout = to;
+	sirfsoc_wdt_updatetimeout(wdd);
+
+	return 0;
+}
+
+#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
+
+static const struct watchdog_info sirfsoc_wdt_ident = {
+	.options          =     OPTIONS,
+	.firmware_version =	0,
+	.identity         =	"SiRFSOC Watchdog",
+};
+
+static struct watchdog_ops sirfsoc_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = sirfsoc_wdt_enable,
+	.stop = sirfsoc_wdt_disable,
+	.get_timeleft = sirfsoc_wdt_gettimeleft,
+	.ping = sirfsoc_wdt_updatetimeout,
+	.set_timeout = sirfsoc_wdt_settimeout,
+};
+
+static struct watchdog_device sirfsoc_wdd = {
+	.info = &sirfsoc_wdt_ident,
+	.ops = &sirfsoc_wdt_ops,
+	.timeout = SIRFSOC_WDT_DEFAULT_TIMEOUT,
+	.min_timeout = SIRFSOC_WDT_MIN_TIMEOUT,
+	.max_timeout = SIRFSOC_WDT_MAX_TIMEOUT,
+};
+
+static int sirfsoc_wdt_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	int ret;
+	void __iomem *base;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	watchdog_set_drvdata(&sirfsoc_wdd, base);
+
+	watchdog_init_timeout(&sirfsoc_wdd, timeout, &pdev->dev);
+	watchdog_set_nowayout(&sirfsoc_wdd, nowayout);
+
+	ret = watchdog_register_device(&sirfsoc_wdd);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, &sirfsoc_wdd);
+
+	return 0;
+}
+
+static void sirfsoc_wdt_shutdown(struct platform_device *pdev)
+{
+	struct watchdog_device *wdd = platform_get_drvdata(pdev);
+
+	sirfsoc_wdt_disable(wdd);
+}
+
+static int sirfsoc_wdt_remove(struct platform_device *pdev)
+{
+	sirfsoc_wdt_shutdown(pdev);
+	return 0;
+}
+
+#ifdef	CONFIG_PM_SLEEP
+static int sirfsoc_wdt_suspend(struct device *dev)
+{
+	return 0;
+}
+
+static int sirfsoc_wdt_resume(struct device *dev)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	/*
+	 * NOTE: Since timer controller registers settings are saved
+	 * and restored back by the timer-prima2.c, so we need not
+	 * update WD settings except refreshing timeout.
+	 */
+	sirfsoc_wdt_updatetimeout(wdd);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(sirfsoc_wdt_pm_ops,
+		sirfsoc_wdt_suspend, sirfsoc_wdt_resume);
+
+static const struct of_device_id sirfsoc_wdt_of_match[] = {
+	{ .compatible = "sirf,prima2-tick"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, sirfsoc_wdt_of_match);
+
+static struct platform_driver sirfsoc_wdt_driver = {
+	.driver = {
+		.name = "sirfsoc-wdt",
+		.owner = THIS_MODULE,
+		.pm = &sirfsoc_wdt_pm_ops,
+		.of_match_table	= of_match_ptr(sirfsoc_wdt_of_match),
+	},
+	.probe = sirfsoc_wdt_probe,
+	.remove = sirfsoc_wdt_remove,
+	.shutdown = sirfsoc_wdt_shutdown,
+};
+module_platform_driver(sirfsoc_wdt_driver);
+
+MODULE_DESCRIPTION("SiRF SoC watchdog driver");
+MODULE_AUTHOR("Xianglong Du <[e-mail]>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:sirfsoc-wdt");