watchdog: Watchdog driver for Broadcom Set-Top Box

Watchdog driver for Broadcom 7038 and newer chips.
Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -1313,6 +1313,14 @@ config BCM_KONA_WDT_DEBUG
 
 	  If in doubt, say 'N'.
 
+config BCM7038_WDT
+	tristate "BCM7038 Watchdog"
+	select WATCHDOG_CORE
+	help
+	 Watchdog driver for the built-in hardware in Broadcom 7038 SoCs.
+
+	 Say 'Y or 'M' here to enable the driver.
+
 config IMGPDC_WDT
 	tristate "Imagination Technologies PDC Watchdog Timer"
 	depends on HAS_IOMEM

drivers/watchdog/Makefile

@@ -68,6 +68,7 @@ obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
 obj-$(CONFIG_MEDIATEK_WATCHDOG) += mtk_wdt.o
 obj-$(CONFIG_DIGICOLOR_WATCHDOG) += digicolor_wdt.o
 obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
+obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/bcm7038_wdt.c

+/*
+ * Copyright (C) 2015 Broadcom Corporation
+ *
+ * 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 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/clk.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/watchdog.h>
+
+#define WDT_START_1		0xff00
+#define WDT_START_2		0x00ff
+#define WDT_STOP_1		0xee00
+#define WDT_STOP_2		0x00ee
+
+#define WDT_TIMEOUT_REG		0x0
+#define WDT_CMD_REG		0x4
+
+#define WDT_MIN_TIMEOUT		1 /* seconds */
+#define WDT_DEFAULT_TIMEOUT	30 /* seconds */
+#define WDT_DEFAULT_RATE	27000000
+
+struct bcm7038_watchdog {
+	void __iomem		*base;
+	struct watchdog_device	wdd;
+	u32			rate;
+	struct clk		*clk;
+};
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+	u32 timeout;
+
+	timeout = wdt->rate * wdog->timeout;
+
+	writel(timeout, wdt->base + WDT_TIMEOUT_REG);
+}
+
+static int bcm7038_wdt_ping(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+
+	writel(WDT_START_1, wdt->base + WDT_CMD_REG);
+	writel(WDT_START_2, wdt->base + WDT_CMD_REG);
+
+	return 0;
+}
+
+static int bcm7038_wdt_start(struct watchdog_device *wdog)
+{
+	bcm7038_wdt_set_timeout_reg(wdog);
+	bcm7038_wdt_ping(wdog);
+
+	return 0;
+}
+
+static int bcm7038_wdt_stop(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+
+	writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
+	writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
+
+	return 0;
+}
+
+static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
+				   unsigned int t)
+{
+	/* Can't modify timeout value if watchdog timer is running */
+	bcm7038_wdt_stop(wdog);
+	wdog->timeout = t;
+	bcm7038_wdt_start(wdog);
+
+	return 0;
+}
+
+static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
+{
+	struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
+	u32 time_left;
+
+	time_left = readl(wdt->base + WDT_CMD_REG);
+
+	return time_left / wdt->rate;
+}
+
+static struct watchdog_info bcm7038_wdt_info = {
+	.identity	= "Broadcom BCM7038 Watchdog Timer",
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+				WDIOF_MAGICCLOSE
+};
+
+static struct watchdog_ops bcm7038_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= bcm7038_wdt_start,
+	.stop		= bcm7038_wdt_stop,
+	.set_timeout	= bcm7038_wdt_set_timeout,
+	.get_timeleft	= bcm7038_wdt_get_timeleft,
+};
+
+static int bcm7038_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct bcm7038_watchdog *wdt;
+	struct resource *res;
+	int err;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, wdt);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	wdt->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(wdt->base))
+		return PTR_ERR(wdt->base);
+
+	wdt->clk = devm_clk_get(dev, NULL);
+	/* If unable to get clock, use default frequency */
+	if (!IS_ERR(wdt->clk)) {
+		clk_prepare_enable(wdt->clk);
+		wdt->rate = clk_get_rate(wdt->clk);
+		/* Prevent divide-by-zero exception */
+		if (!wdt->rate)
+			wdt->rate = WDT_DEFAULT_RATE;
+	} else {
+		wdt->rate = WDT_DEFAULT_RATE;
+		wdt->clk = NULL;
+	}
+
+	wdt->wdd.info		= &bcm7038_wdt_info;
+	wdt->wdd.ops		= &bcm7038_wdt_ops;
+	wdt->wdd.min_timeout	= WDT_MIN_TIMEOUT;
+	wdt->wdd.timeout	= WDT_DEFAULT_TIMEOUT;
+	wdt->wdd.max_timeout	= 0xffffffff / wdt->rate;
+	wdt->wdd.parent		= dev;
+	watchdog_set_drvdata(&wdt->wdd, wdt);
+
+	err = watchdog_register_device(&wdt->wdd);
+	if (err) {
+		dev_err(dev, "Failed to register watchdog device\n");
+		clk_disable_unprepare(wdt->clk);
+		return err;
+	}
+
+	dev_info(dev, "Registered BCM7038 Watchdog\n");
+
+	return 0;
+}
+
+static int bcm7038_wdt_remove(struct platform_device *pdev)
+{
+	struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
+
+	if (!nowayout)
+		bcm7038_wdt_stop(&wdt->wdd);
+
+	watchdog_unregister_device(&wdt->wdd);
+	clk_disable_unprepare(wdt->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int bcm7038_wdt_suspend(struct device *dev)
+{
+	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&wdt->wdd))
+		return bcm7038_wdt_stop(&wdt->wdd);
+
+	return 0;
+}
+
+static int bcm7038_wdt_resume(struct device *dev)
+{
+	struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&wdt->wdd))
+		return bcm7038_wdt_start(&wdt->wdd);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
+			 bcm7038_wdt_resume);
+
+static void bcm7038_wdt_shutdown(struct platform_device *pdev)
+{
+	struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
+
+	if (watchdog_active(&wdt->wdd))
+		bcm7038_wdt_stop(&wdt->wdd);
+}
+
+static const struct of_device_id bcm7038_wdt_match[] = {
+	{ .compatible = "brcm,bcm7038-wdt" },
+	{},
+};
+
+static struct platform_driver bcm7038_wdt_driver = {
+	.probe		= bcm7038_wdt_probe,
+	.remove		= bcm7038_wdt_remove,
+	.shutdown	= bcm7038_wdt_shutdown,
+	.driver		= {
+		.name		= "bcm7038-wdt",
+		.of_match_table	= bcm7038_wdt_match,
+		.pm		= &bcm7038_wdt_pm_ops,
+	}
+};
+module_platform_driver(bcm7038_wdt_driver);
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
+MODULE_AUTHOR("Justin Chen");