watchdog: uniphier: add UniPhier watchdog driver

Add a watchdog driver for Socionext UniPhier series SoC.
Note that the timeout value for this device must be a power
of 2 because of the specification.

Signed-off-by: Keiji Hayashibara <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

Documentation/watchdog/watchdog-parameters.txt

···
 nowayout: Watchdog cannot be stopped once started
 	(default=kernel config parameter)
 -------------------------------------------------
+uniphier_wdt:
+timeout: Watchdog timeout in power of two seconds.
+	(1 <= timeout <= 128, default=64)
+nowayout: Watchdog cannot be stopped once started
+	(default=kernel config parameter)
+-------------------------------------------------
 w83627hf_wdt:
 wdt_io: w83627hf/thf WDT io port (default 0x2E)
 timeout: Watchdog timeout in seconds. 1 <= timeout <= 255, default=60.

drivers/watchdog/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called stm32_iwdg.
 
+config UNIPHIER_WATCHDOG
+	tristate "UniPhier watchdog support"
+	depends on ARCH_UNIPHIER || COMPILE_TEST
+	depends on OF && MFD_SYSCON
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support watchdog timer embedded
+	  into the UniPhier system.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called uniphier_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

···
 obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
 obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
 obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
+obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/uniphier_wdt.c

···
+/*
+ * Watchdog driver for the UniPhier watchdog timer
+ *
+ * (c) Copyright 2014 Panasonic Corporation
+ * (c) Copyright 2016 Socionext Inc.
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * 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/bitops.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+/* WDT timer setting register */
+#define WDTTIMSET			0x3004
+#define   WDTTIMSET_PERIOD_MASK		(0xf << 0)
+#define   WDTTIMSET_PERIOD_1_SEC	(0x3 << 0)
+
+/* WDT reset selection register */
+#define WDTRSTSEL			0x3008
+#define   WDTRSTSEL_RSTSEL_MASK		(0x3 << 0)
+#define   WDTRSTSEL_RSTSEL_BOTH		(0x0 << 0)
+#define   WDTRSTSEL_RSTSEL_IRQ_ONLY	(0x2 << 0)
+
+/* WDT control register */
+#define WDTCTRL				0x300c
+#define   WDTCTRL_STATUS		BIT(8)
+#define   WDTCTRL_CLEAR			BIT(1)
+#define   WDTCTRL_ENABLE		BIT(0)
+
+#define SEC_TO_WDTTIMSET_PRD(sec) \
+		(ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)
+
+#define WDTST_TIMEOUT			1000 /* usec */
+
+#define WDT_DEFAULT_TIMEOUT		64   /* Default is 64 seconds */
+#define WDT_PERIOD_MIN			1
+#define WDT_PERIOD_MAX			128
+
+static unsigned int timeout = 0;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+struct uniphier_wdt_dev {
+	struct watchdog_device wdt_dev;
+	struct regmap	*regmap;
+};
+
+/*
+ * UniPhier Watchdog operations
+ */
+static int uniphier_watchdog_ping(struct watchdog_device *w)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+	unsigned int val;
+	int ret;
+
+	/* Clear counter */
+	ret = regmap_write_bits(wdev->regmap, WDTCTRL,
+				WDTCTRL_CLEAR, WDTCTRL_CLEAR);
+	if (!ret)
+		/*
+		 * As SoC specification, after clear counter,
+		 * it needs to wait until counter status is 1.
+		 */
+		ret = regmap_read_poll_timeout(wdev->regmap, WDTCTRL, val,
+					       (val & WDTCTRL_STATUS),
+					       0, WDTST_TIMEOUT);
+
+	return ret;
+}
+
+static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
+				       !(val & WDTCTRL_STATUS),
+				       0, WDTST_TIMEOUT);
+	if (ret)
+		return ret;
+
+	/* Setup period */
+	ret = regmap_write(regmap, WDTTIMSET,
+			   SEC_TO_WDTTIMSET_PRD(sec));
+	if (ret)
+		return ret;
+
+	/* Enable and clear watchdog */
+	ret = regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
+	if (!ret)
+		/*
+		 * As SoC specification, after clear counter,
+		 * it needs to wait until counter status is 1.
+		 */
+		ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
+					       (val & WDTCTRL_STATUS),
+					       0, WDTST_TIMEOUT);
+
+	return ret;
+}
+
+static int __uniphier_watchdog_stop(struct regmap *regmap)
+{
+	/* Disable and stop watchdog */
+	return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
+}
+
+static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
+{
+	int ret;
+
+	ret = __uniphier_watchdog_stop(regmap);
+	if (ret)
+		return ret;
+
+	return __uniphier_watchdog_start(regmap, sec);
+}
+
+static int uniphier_watchdog_start(struct watchdog_device *w)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+	unsigned int tmp_timeout;
+
+	tmp_timeout = roundup_pow_of_two(w->timeout);
+
+	return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
+}
+
+static int uniphier_watchdog_stop(struct watchdog_device *w)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+
+	return __uniphier_watchdog_stop(wdev->regmap);
+}
+
+static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
+					 unsigned int t)
+{
+	struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
+	unsigned int tmp_timeout;
+	int ret;
+
+	tmp_timeout = roundup_pow_of_two(t);
+	if (tmp_timeout == w->timeout)
+		return 0;
+
+	if (watchdog_active(w)) {
+		ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
+		if (ret)
+			return ret;
+	}
+
+	w->timeout = tmp_timeout;
+
+	return 0;
+}
+
+/*
+ * Kernel Interfaces
+ */
+static const struct watchdog_info uniphier_wdt_info = {
+	.identity	= "uniphier-wdt",
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE |
+			  WDIOF_OVERHEAT,
+};
+
+static const struct watchdog_ops uniphier_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= uniphier_watchdog_start,
+	.stop		= uniphier_watchdog_stop,
+	.ping		= uniphier_watchdog_ping,
+	.set_timeout	= uniphier_watchdog_set_timeout,
+};
+
+static int uniphier_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_wdt_dev *wdev;
+	struct regmap *regmap;
+	struct device_node *parent;
+	int ret;
+
+	wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
+	if (!wdev)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, wdev);
+
+	parent = of_get_parent(dev->of_node); /* parent should be syscon node */
+	regmap = syscon_node_to_regmap(parent);
+	of_node_put(parent);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	wdev->regmap = regmap;
+	wdev->wdt_dev.info = &uniphier_wdt_info;
+	wdev->wdt_dev.ops = &uniphier_wdt_ops;
+	wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
+	wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
+	wdev->wdt_dev.parent = dev;
+
+	if (watchdog_init_timeout(&wdev->wdt_dev, timeout, dev) < 0) {
+		wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
+	}
+	watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
+	watchdog_stop_on_reboot(&wdev->wdt_dev);
+
+	watchdog_set_drvdata(&wdev->wdt_dev, wdev);
+
+	uniphier_watchdog_stop(&wdev->wdt_dev);
+	ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
+	if (ret)
+		return ret;
+
+	ret = devm_watchdog_register_device(dev, &wdev->wdt_dev);
+	if (ret)
+		return ret;
+
+	dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
+		 wdev->wdt_dev.timeout, nowayout);
+
+	return 0;
+}
+
+static const struct of_device_id uniphier_wdt_dt_ids[] = {
+	{ .compatible = "socionext,uniphier-wdt" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);
+
+static struct platform_driver uniphier_wdt_driver = {
+	.probe		= uniphier_wdt_probe,
+	.driver		= {
+		.name		= "uniphier-wdt",
+		.of_match_table	= uniphier_wdt_dt_ids,
+	},
+};
+
+module_platform_driver(uniphier_wdt_driver);
+
+module_param(timeout, uint, 0000);
+MODULE_PARM_DESC(timeout,
+	"Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
+				__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
+
+module_param(nowayout, bool, 0000);
+MODULE_PARM_DESC(nowayout,
+	"Watchdog cannot be stopped once started (default="
+				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+MODULE_AUTHOR("Keiji Hayashibara <[e-mail]>");
+MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
+MODULE_LICENSE("GPL v2");