1 files changed, 350 insertions, 0 deletions
diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
new file mode 100644
index 000000000..501aebb5b
--- /dev/null
+++ b/drivers/watchdog/dw_wdt.c
@@ -0,0 +1,350 @@
+/*
+ * Copyright 2010-2011 Picochip Ltd., Jamie Iles
+ * http://www.picochip.com
+ *
+ * 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.
+ *
+ * This file implements a driver for the Synopsys DesignWare watchdog device
+ * in the many subsystems. The watchdog has 16 different timeout periods
+ * and these are a function of the input clock frequency.
+ *
+ * The DesignWare watchdog cannot be stopped once it has been started so we
+ * do not implement a stop function. The watchdog core will continue to send
+ * heartbeat requests after the watchdog device has been closed.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+#define WDOG_CONTROL_REG_OFFSET		    0x00
+#define WDOG_CONTROL_REG_WDT_EN_MASK	    0x01
+#define WDOG_CONTROL_REG_RESP_MODE_MASK	    0x02
+#define WDOG_TIMEOUT_RANGE_REG_OFFSET	    0x04
+#define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
+#define WDOG_CURRENT_COUNT_REG_OFFSET	    0x08
+#define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
+#define WDOG_COUNTER_RESTART_KICK_VALUE	    0x76
+
+/* The maximum TOP (timeout period) value that can be set in the watchdog. */
+#define DW_WDT_MAX_TOP		15
+
+#define DW_WDT_DEFAULT_SECONDS	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) ")");
+
+struct dw_wdt {
+	void __iomem		*regs;
+	struct clk		*clk;
+	unsigned long		rate;
+	struct watchdog_device	wdd;
+	struct reset_control	*rst;
+	/* Save/restore */
+	u32			control;
+	u32			timeout;
+};
+
+#define to_dw_wdt(wdd)	container_of(wdd, struct dw_wdt, wdd)
+
+static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
+{
+	return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
+		WDOG_CONTROL_REG_WDT_EN_MASK;
+}
+
+static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
+{
+	/*
+	 * There are 16 possible timeout values in 0..15 where the number of
+	 * cycles is 2 ^ (16 + i) and the watchdog counts down.
+	 */
+	return (1U << (16 + top)) / dw_wdt->rate;
+}
+
+static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
+{
+	int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
+
+	return dw_wdt_top_in_seconds(dw_wdt, top);
+}
+
+static int dw_wdt_ping(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
+	       WDOG_COUNTER_RESTART_REG_OFFSET);
+
+	return 0;
+}
+
+static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+	int i, top_val = DW_WDT_MAX_TOP;
+
+	/*
+	 * Iterate over the timeout values until we find the closest match. We
+	 * always look for >=.
+	 */
+	for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
+		if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
+			top_val = i;
+			break;
+		}
+
+	/*
+	 * Set the new value in the watchdog.  Some versions of dw_wdt
+	 * have have TOPINIT in the TIMEOUT_RANGE register (as per
+	 * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
+	 * effectively get a pat of the watchdog right here.
+	 */
+	writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
+	       dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+
+	wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
+
+	return 0;
+}
+
+static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt)
+{
+	u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
+
+	/* Disable interrupt mode; always perform system reset. */
+	val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK;
+	/* Enable watchdog. */
+	val |= WDOG_CONTROL_REG_WDT_EN_MASK;
+	writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
+}
+
+static int dw_wdt_start(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	dw_wdt_set_timeout(wdd, wdd->timeout);
+	dw_wdt_arm_system_reset(dw_wdt);
+
+	return 0;
+}
+
+static int dw_wdt_stop(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	if (!dw_wdt->rst) {
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+		return 0;
+	}
+
+	reset_control_assert(dw_wdt->rst);
+	reset_control_deassert(dw_wdt->rst);
+
+	return 0;
+}
+
+static int dw_wdt_restart(struct watchdog_device *wdd,
+			  unsigned long action, void *data)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+	if (dw_wdt_is_enabled(dw_wdt))
+		writel(WDOG_COUNTER_RESTART_KICK_VALUE,
+		       dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
+	else
+		dw_wdt_arm_system_reset(dw_wdt);
+
+	/* wait for reset to assert... */
+	mdelay(500);
+
+	return 0;
+}
+
+static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
+
+	return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
+		dw_wdt->rate;
+}
+
+static const struct watchdog_info dw_wdt_ident = {
+	.options	= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+			  WDIOF_MAGICCLOSE,
+	.identity	= "Synopsys DesignWare Watchdog",
+};
+
+static const struct watchdog_ops dw_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= dw_wdt_start,
+	.stop		= dw_wdt_stop,
+	.ping		= dw_wdt_ping,
+	.set_timeout	= dw_wdt_set_timeout,
+	.get_timeleft	= dw_wdt_get_timeleft,
+	.restart	= dw_wdt_restart,
+};
+
+#ifdef CONFIG_PM_SLEEP
+static int dw_wdt_suspend(struct device *dev)
+{
+	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
+
+	dw_wdt->control = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
+	dw_wdt->timeout = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+
+	clk_disable_unprepare(dw_wdt->clk);
+
+	return 0;
+}
+
+static int dw_wdt_resume(struct device *dev)
+{
+	struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
+	int err = clk_prepare_enable(dw_wdt->clk);
+
+	if (err)
+		return err;
+
+	writel(dw_wdt->timeout, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+	writel(dw_wdt->control, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
+
+	dw_wdt_ping(&dw_wdt->wdd);
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
+
+static int dw_wdt_drv_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	struct dw_wdt *dw_wdt;
+	struct resource *mem;
+	int ret;
+
+	dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
+	if (!dw_wdt)
+		return -ENOMEM;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	dw_wdt->regs = devm_ioremap_resource(dev, mem);
+	if (IS_ERR(dw_wdt->regs))
+		return PTR_ERR(dw_wdt->regs);
+
+	dw_wdt->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(dw_wdt->clk))
+		return PTR_ERR(dw_wdt->clk);
+
+	ret = clk_prepare_enable(dw_wdt->clk);
+	if (ret)
+		return ret;
+
+	dw_wdt->rate = clk_get_rate(dw_wdt->clk);
+	if (dw_wdt->rate == 0) {
+		ret = -EINVAL;
+		goto out_disable_clk;
+	}
+
+	dw_wdt->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
+	if (IS_ERR(dw_wdt->rst)) {
+		ret = PTR_ERR(dw_wdt->rst);
+		goto out_disable_clk;
+	}
+
+	reset_control_deassert(dw_wdt->rst);
+
+	wdd = &dw_wdt->wdd;
+	wdd->info = &dw_wdt_ident;
+	wdd->ops = &dw_wdt_ops;
+	wdd->min_timeout = 1;
+	wdd->max_hw_heartbeat_ms =
+		dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
+	wdd->parent = dev;
+
+	watchdog_set_drvdata(wdd, dw_wdt);
+	watchdog_set_nowayout(wdd, nowayout);
+	watchdog_init_timeout(wdd, 0, dev);
+
+	/*
+	 * If the watchdog is already running, use its already configured
+	 * timeout. Otherwise use the default or the value provided through
+	 * devicetree.
+	 */
+	if (dw_wdt_is_enabled(dw_wdt)) {
+		wdd->timeout = dw_wdt_get_top(dw_wdt);
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+	} else {
+		wdd->timeout = DW_WDT_DEFAULT_SECONDS;
+		watchdog_init_timeout(wdd, 0, dev);
+	}
+
+	platform_set_drvdata(pdev, dw_wdt);
+
+	watchdog_set_restart_priority(wdd, 128);
+
+	ret = watchdog_register_device(wdd);
+	if (ret)
+		goto out_disable_clk;
+
+	return 0;
+
+out_disable_clk:
+	clk_disable_unprepare(dw_wdt->clk);
+	return ret;
+}
+
+static int dw_wdt_drv_remove(struct platform_device *pdev)
+{
+	struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&dw_wdt->wdd);
+	reset_control_assert(dw_wdt->rst);
+	clk_disable_unprepare(dw_wdt->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id dw_wdt_of_match[] = {
+	{ .compatible = "snps,dw-wdt", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
+#endif
+
+static struct platform_driver dw_wdt_driver = {
+	.probe		= dw_wdt_drv_probe,
+	.remove		= dw_wdt_drv_remove,
+	.driver		= {
+		.name	= "dw_wdt",
+		.of_match_table = of_match_ptr(dw_wdt_of_match),
+		.pm	= &dw_wdt_pm_ops,
+	},
+};
+
+module_platform_driver(dw_wdt_driver);
+
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
+MODULE_LICENSE("GPL");