[v3,3/3] watchdog: zx2967: add watchdog controller driver for ZTE's zx2967 family

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index acb00b5..05093a2 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -714,6 +714,16 @@  config ASPEED_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called aspeed_wdt.
 
+config ZX2967_WATCHDOG
+	tristate "ZTE zx2967 SoCs watchdog support"
+	depends on ARCH_ZX
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the watchdog timer
+	  in ZTE zx2967 SoCs.
+	  To compile this driver as a module, choose M here: the
+	  module will be called zx2967_wdt.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 0c3d35e..bf2d296 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -82,6 +82,7 @@  obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
 obj-$(CONFIG_ATLAS7_WATCHDOG) += atlas7_wdt.o
 obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
 obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
+obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/zx2967_wdt.c b/drivers/watchdog/zx2967_wdt.c
new file mode 100644
index 0000000..a5656d0
--- /dev/null
+++ b/drivers/watchdog/zx2967_wdt.c
@@ -0,0 +1,376 @@ 
+/*
+ * watchdog driver for ZTE's zx2967 family
+ *
+ * Copyright (C) 2017 ZTE Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+#define ZX2967_WDT_CFG_REG			0x4
+#define ZX2967_WDT_LOAD_REG			0x8
+#define ZX2967_WDT_REFRESH_REG			0x18
+#define ZX2967_WDT_START_REG			0x1c
+
+#define ZX2967_WDT_REFRESH_MASK			0x3f
+
+#define ZX2967_WDT_CFG_DIV(n)			((((n) & 0xff) - 1) << 8)
+#define ZX2967_WDT_START_EN			0x1
+
+#define ZX2967_WDT_WRITEKEY			0x12340000
+
+#define ZX2967_WDT_DIV_DEFAULT			16
+#define ZX2967_WDT_DEFAULT_TIMEOUT		32
+#define ZX2967_WDT_MIN_TIMEOUT			1
+#define ZX2967_WDT_MAX_TIMEOUT			500
+#define ZX2967_WDT_MAX_COUNT			0xffff
+
+#define ZX2967_WDT_FLAG_REBOOT_MON		(1 << 0)
+
+struct zx2967_wdt {
+	struct device		*dev;
+	struct clk		*clock;
+	void __iomem		*reg_base;
+	unsigned int		conf;
+	unsigned int		load;
+	unsigned int		flags;
+	struct watchdog_device	wdt_device;
+	struct notifier_block	restart_handler;
+	struct notifier_block	reboot_handler;
+};
+
+static inline u32 zx2967_wdt_readl(struct zx2967_wdt *wdt, u16 reg)
+{
+	return readl_relaxed(wdt->reg_base + reg);
+}
+
+static inline void zx2967_wdt_writel(struct zx2967_wdt *wdt, u16 reg, u32 val)
+{
+	writel_relaxed(val | ZX2967_WDT_WRITEKEY, wdt->reg_base + reg);
+}
+
+static void zx2967_wdt_refresh(struct zx2967_wdt *wdt)
+{
+	u32 val;
+
+	val = zx2967_wdt_readl(wdt, ZX2967_WDT_REFRESH_REG);
+	val ^= ZX2967_WDT_REFRESH_MASK;
+	zx2967_wdt_writel(wdt, ZX2967_WDT_REFRESH_REG, val);
+}
+
+static unsigned int
+__zx2967_wdt_set_timeout(struct zx2967_wdt *wdt, unsigned int timeout)
+{
+	unsigned int freq = clk_get_rate(wdt->clock);
+	unsigned int divisor = ZX2967_WDT_DIV_DEFAULT;
+	unsigned int count;
+
+	count = timeout * freq;
+	if (count > divisor * ZX2967_WDT_MAX_COUNT)
+		divisor = DIV_ROUND_UP(count, ZX2967_WDT_MAX_COUNT);
+	count = DIV_ROUND_UP(count, divisor);
+	zx2967_wdt_writel(wdt, ZX2967_WDT_CFG_REG, ZX2967_WDT_CFG_DIV(divisor));
+	zx2967_wdt_writel(wdt, ZX2967_WDT_LOAD_REG, count);
+	zx2967_wdt_refresh(wdt);
+	wdt->load = count;
+
+	return (count * divisor) / freq;
+}
+
+static int zx2967_wdt_set_timeout(struct watchdog_device *wdd,
+				  unsigned int timeout)
+{
+	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	if (watchdog_timeout_invalid(&wdt->wdt_device, timeout)) {
+		dev_err(wdt->dev, "timeout %d is invalid\n", timeout);
+		return -EINVAL;
+	}
+
+	wdd->timeout = __zx2967_wdt_set_timeout(wdt, timeout);
+
+	return 0;
+}
+
+static void __zx2967_wdt_start(struct zx2967_wdt *wdt)
+{
+	u32 val;
+
+	val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
+	val |= ZX2967_WDT_START_EN;
+	zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG, val);
+}
+
+static void __zx2967_wdt_stop(struct zx2967_wdt *wdt)
+{
+	u32 val;
+
+	val = zx2967_wdt_readl(wdt, ZX2967_WDT_START_REG);
+	val &= ~ZX2967_WDT_START_EN;
+	zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG, val);
+}
+
+static int zx2967_wdt_start(struct watchdog_device *wdd)
+{
+	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	__zx2967_wdt_stop(wdt);
+	zx2967_wdt_set_timeout(wdd, wdd->timeout);
+	__zx2967_wdt_start(wdt);
+
+	return 0;
+}
+
+static int zx2967_wdt_stop(struct watchdog_device *wdd)
+{
+	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	__zx2967_wdt_stop(wdt);
+
+	return 0;
+}
+
+static int zx2967_wdt_keepalive(struct watchdog_device *wdd)
+{
+	struct zx2967_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	zx2967_wdt_refresh(wdt);
+
+	return 0;
+}
+
+#define ZX2967_WDT_OPTIONS \
+	(WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
+static const struct watchdog_info zx2967_wdt_ident = {
+	.options          =     ZX2967_WDT_OPTIONS,
+	.firmware_version =	0,
+	.identity         =	"zx2967 watchdog",
+};
+
+static struct watchdog_ops zx2967_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = zx2967_wdt_start,
+	.stop = zx2967_wdt_stop,
+	.ping = zx2967_wdt_keepalive,
+	.set_timeout = zx2967_wdt_set_timeout,
+};
+
+static void zx2967_wdt_fix_sysdown(struct zx2967_wdt *wdt)
+{
+	__zx2967_wdt_stop(wdt);
+	__zx2967_wdt_set_timeout(wdt, 15);
+	__zx2967_wdt_start(wdt);
+}
+
+static int zx2967_wdt_notify_sys(struct notifier_block *this,
+			     unsigned long code, void *unused)
+{
+	struct zx2967_wdt *wdt = container_of(this, struct zx2967_wdt,
+					      reboot_handler);
+
+	wdt->flags |= ZX2967_WDT_FLAG_REBOOT_MON;
+	switch (code) {
+	case SYS_HALT:
+	case SYS_POWER_OFF:
+	case SYS_RESTART:
+		zx2967_wdt_fix_sysdown(wdt);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int zx2967_wdt_restart(struct notifier_block *this,
+			      unsigned long mode, void *cmd)
+{
+	struct zx2967_wdt *wdt;
+
+	wdt = container_of(this, struct zx2967_wdt, restart_handler);
+
+	zx2967_wdt_stop(&wdt->wdt_device);
+
+	zx2967_wdt_writel(wdt, ZX2967_WDT_LOAD_REG, 0x80);
+	zx2967_wdt_refresh(wdt);
+	zx2967_wdt_writel(wdt, ZX2967_WDT_START_REG, ZX2967_WDT_START_EN);
+
+	zx2967_wdt_start(&wdt->wdt_device);
+	/* wait for reset*/
+	mdelay(500);
+
+	return NOTIFY_DONE;
+}
+
+static void zx2967_wdt_reset_sysctrl(struct device *dev)
+{
+	int ret;
+	struct device_node *np = NULL;
+	void __iomem *regmap;
+	unsigned int offset, mask, config;
+	struct of_phandle_args out_args;
+
+	ret = of_parse_phandle_with_fixed_args(dev->of_node,
+			"zte,wdt-reset-sysctrl", 3, 0, &out_args);
+	if (ret) {
+		dev_info(dev, "failed to parse zte,wdt-reset-sysctrl");
+		return;
+	}
+	offset = out_args.args[0];
+	config = out_args.args[1];
+	mask = out_args.args[2];
+
+	regmap = syscon_node_to_regmap(out_args.np);
+	if (IS_ERR(regmap))
+		goto out;
+
+	regmap_update_bits(regmap, offset, mask, config);
+out:
+	of_node_put(np);
+}
+
+static int zx2967_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev;
+	struct zx2967_wdt *wdt;
+	struct resource *base;
+	int ret = 0;
+
+	struct reset_control *rstc;
+
+	dev = &pdev->dev;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, wdt);
+
+	wdt->dev = dev;
+	wdt->wdt_device.info = &zx2967_wdt_ident;
+	wdt->wdt_device.ops = &zx2967_wdt_ops;
+	wdt->wdt_device.timeout = ZX2967_WDT_DEFAULT_TIMEOUT;
+	wdt->wdt_device.max_timeout = ZX2967_WDT_MAX_TIMEOUT;
+	wdt->wdt_device.min_timeout = ZX2967_WDT_MIN_TIMEOUT;
+	wdt->wdt_device.parent = &pdev->dev;
+
+	base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	wdt->reg_base = devm_ioremap_resource(dev, base);
+	if (IS_ERR(wdt->reg_base)) {
+		dev_err(dev, "ioremap failed\n");
+		return PTR_ERR(wdt->reg_base);
+	}
+
+	zx2967_wdt_reset_sysctrl(dev);
+
+	wdt->reboot_handler.notifier_call = zx2967_wdt_notify_sys;
+	register_reboot_notifier(&wdt->reboot_handler);
+	wdt->clock = devm_clk_get(dev, NULL);
+	if (IS_ERR(wdt->clock)) {
+		dev_err(dev, "failed to find watchdog clock source\n");
+		return PTR_ERR(wdt->clock);
+	}
+
+	ret = clk_prepare_enable(wdt->clock);
+	if (ret < 0) {
+		dev_err(dev, "failed to enable clock\n");
+		return ret;
+	}
+	clk_set_rate(wdt->clock, 32768);
+
+	rstc = devm_reset_control_get(dev, NULL);
+	if (IS_ERR(rstc)) {
+		dev_err(dev, "failed to get rstc");
+		ret = PTR_ERR(rstc);
+		goto fail_get_reset_control;
+	}
+
+	reset_control_assert(rstc);
+	mdelay(10);
+	reset_control_deassert(rstc);
+
+	watchdog_set_drvdata(&wdt->wdt_device, wdt);
+
+	watchdog_init_timeout(&wdt->wdt_device,
+			      ZX2967_WDT_DEFAULT_TIMEOUT, dev);
+	watchdog_set_nowayout(&wdt->wdt_device, WATCHDOG_NOWAYOUT);
+
+	zx2967_wdt_stop(&wdt->wdt_device);
+
+	ret = watchdog_register_device(&wdt->wdt_device);
+	if (ret)
+		goto fail_register;
+
+	wdt->restart_handler.notifier_call = zx2967_wdt_restart;
+	wdt->restart_handler.priority = 128;
+	ret = register_restart_handler(&wdt->restart_handler);
+	if (ret) {
+		dev_err(dev, "cannot register restart handler, %d\n", ret);
+		goto fail_restart;
+	}
+
+	dev_info(dev, "watchdog enabled (timeout=%d sec, nowayout=%d)",
+		 wdt->wdt_device.timeout, WATCHDOG_NOWAYOUT);
+
+	return 0;
+
+fail_get_reset_control:
+fail_restart:
+	watchdog_unregister_device(&wdt->wdt_device);
+fail_register:
+	clk_disable_unprepare(wdt->clock);
+	return ret;
+}
+
+static int zx2967_wdt_remove(struct platform_device *pdev)
+{
+	struct zx2967_wdt *wdt = platform_get_drvdata(pdev);
+
+	unregister_restart_handler(&wdt->restart_handler);
+	watchdog_unregister_device(&wdt->wdt_device);
+	clk_disable_unprepare(wdt->clock);
+
+	return 0;
+}
+
+static void zx2967_wdt_shutdown(struct platform_device *pdev)
+{
+	struct zx2967_wdt *wdt = platform_get_drvdata(pdev);
+
+	if (!(wdt->flags & ZX2967_WDT_FLAG_REBOOT_MON))
+		zx2967_wdt_stop(&wdt->wdt_device);
+}
+
+static const struct of_device_id zx2967_wdt_match[] = {
+	{ .compatible = "zte,zx296718-wdt", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, zx2967_wdt_match);
+
+static struct platform_driver zx2967_wdt_driver = {
+	.probe		= zx2967_wdt_probe,
+	.remove		= zx2967_wdt_remove,
+	.shutdown	= zx2967_wdt_shutdown,
+	.driver		= {
+		.name	= "zx2967-wdt",
+		.of_match_table	= of_match_ptr(zx2967_wdt_match),
+	},
+};
+module_platform_driver(zx2967_wdt_driver);
+
+MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
+MODULE_DESCRIPTION("ZTE zx2967 Watchdog Device Driver");
+MODULE_LICENSE("GPL v2");