watchdog: Add watchdog driver for Sunplus SP7021

Sunplus SP7021 requires watchdog timer support.
Add watchdog driver to enable this.

Signed-off-by: Xiantao Hu <xt.hu@cqplus1.com>

MAINTAINERS

@@ -17935,6 +17935,12 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/ethernet/dlink/sundance.c
 
+SUNPLUS WATCHDOG DRIVER
+M:	Xiantao Hu <xt.hu@cqplus1.com>
+L:	linux-watchdog@vger.kernel.org
+S:	Maintained
+F:	drivers/watchdog/sunplus_wdt.c
+
 SUPERH
 M:	Yoshinori Sato <ysato@users.sourceforge.jp>
 M:	Rich Felker <dalias@libc.org>

drivers/watchdog/Kconfig

@@ -990,6 +990,17 @@ config MSC313E_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called msc313e_wdt.
 
+config SUNPLUS_WATCHDOG
+	tristate "Sunplus watchdog support"
+	depends on ARCH_SUNPLUS || COMPILE_TEST
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the watchdog timer
+	  in Sunplus SoCs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called sunplus_wdt.
+
 # X86 (i386 + ia64 + x86_64) Architecture
 
 config ACQUIRE_WDT

drivers/watchdog/Makefile

@@ -94,6 +94,7 @@ obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
 obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
 obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
 obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o
+obj-$(CONFIG_SUNPLUS_WATCHDOG) += sunplus_wdt.o
 
 # X86 (i386 + ia64 + x86_64) Architecture
 obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o

drivers/watchdog/sunplus_wdt.c

@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sunplus Watchdog Driver
+ *
+ * Copyright (C) 2021 Sunplus Technology Co., Ltd.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+#define WDT_CTRL                0x00
+#define WDT_CNT                 0x04
+
+#define WDT_STOP				0x3877
+#define WDT_RESUME				0x4A4B
+#define WDT_CLRIRQ				0x7482
+#define WDT_UNLOCK				0xAB00
+#define WDT_LOCK				0xAB01
+#define WDT_CONMAX				0xDEAF
+
+#define RBUS_WDT_RST        BIT(1)
+#define STC_WDT_RST         BIT(4)
+
+#define MASK_SET(mask)		((mask) | (mask << 16))
+
+#define SP_WDT_MAX_TIMEOUT		11
+#define SP_WDT_MIN_TIMEOUT		1
+
+#define STC_CLK				90000
+
+#define DEVICE_NAME		"sunplus-wdt"
+
+static unsigned int timeout;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
+
+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 sp_wdt_priv {
+	struct watchdog_device wdev;
+	void __iomem *base;
+	void __iomem *miscellaneous;
+	struct clk *clk;
+	struct reset_control *rstc;
+};
+
+static int sp_wdt_restart(struct watchdog_device *wdev,
+			       unsigned long action, void *data)
+{
+	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	void __iomem *base;
+
+	base = priv->base;
+	writel(WDT_STOP, base + WDT_CTRL);
+	writel(WDT_UNLOCK, base + WDT_CTRL);
+	writel(0x0001, base + WDT_CNT);
+	writel(WDT_RESUME, base + WDT_CTRL);
+
+	return 0;
+}
+
+/* TIMEOUT_MAX = ffff0/90kHz =11.65,so longer than 11 seconds will time out */
+static int sp_wdt_ping(struct watchdog_device *wdev)
+{
+	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	void __iomem *base = priv->base;
+	u32 count;
+
+	writel(WDT_STOP, base + WDT_CTRL);
+	writel(WDT_UNLOCK, base + WDT_CTRL);
+	/* tiemrw_cnt[3:0]cant be write,only [19:4] can be write. */
+	count = (wdev->timeout * STC_CLK) >> 4;
+	writel(count, base + WDT_CNT);
+	writel(WDT_RESUME, base + WDT_CTRL);
+
+	return 0;
+}
+
+static int sp_wdt_set_timeout(struct watchdog_device *wdev,
+				   unsigned int timeout)
+{
+	wdev->timeout = timeout;
+
+	return 0;
+}
+
+static int sp_wdt_stop(struct watchdog_device *wdev)
+{
+	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	void __iomem *base = priv->base;
+
+	writel(WDT_STOP, base + WDT_CTRL);
+
+	return 0;
+}
+
+static int sp_wdt_start(struct watchdog_device *wdev)
+{
+	int ret;
+
+	ret = sp_wdt_set_timeout(wdev, wdev->timeout);
+	if (ret < 0)
+		return ret;
+
+	sp_wdt_ping(wdev);
+
+	return 0;
+}
+
+static unsigned int sp_wdt_get_timeleft(struct watchdog_device *wdev)
+{
+	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	void __iomem *base = priv->base;
+	u32 val;
+
+	val = readl(base + WDT_CNT);
+	val &= 0xffff;
+	val = val << 4;
+
+	return val;
+}
+
+/*
+ * 1.We need to reset watchdog flag(clear watchdog interrupt) here
+ * because watchdog timer driver does not have an interrupt handler,
+ * and before enalbe STC and RBUS watchdog timeout. Otherwise,
+ * the intr is always in the triggered state.
+ * 2.enable STC and RBUS watchdog timeout trigger.
+ * 3.watchdog conuter is running, need to be stopped.
+ */
+static int sp_wdt_hw_init(struct watchdog_device *wdev)
+{
+	struct sp_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	void __iomem *base = priv->base;
+	void __iomem *miscellaneous = priv->miscellaneous;
+	u32 val;
+
+	writel(WDT_CLRIRQ, base + WDT_CTRL);
+	val = readl(miscellaneous);
+	val |= MASK_SET(STC_WDT_RST);
+	val |= MASK_SET(RBUS_WDT_RST);
+	writel(val, miscellaneous);
+
+	sp_wdt_stop(wdev);
+
+	return 0;
+}
+
+static const struct watchdog_info sp_wdt_info = {
+	.identity = DEVICE_NAME,
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+};
+
+static const struct watchdog_ops sp_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = sp_wdt_start,
+	.stop = sp_wdt_stop,
+	.ping = sp_wdt_ping,
+	.set_timeout = sp_wdt_set_timeout,
+	.get_timeleft = sp_wdt_get_timeleft,
+	.restart = sp_wdt_restart,
+};
+
+static int sp_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sp_wdt_priv *priv;
+	struct resource *wdt_res;
+	struct clk *clk;
+	int err;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "Can't find clock source\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	err = clk_prepare_enable(clk);
+	if (err) {
+		dev_err(dev, "Clock can't be enabled correctly\n");
+		return err;
+	}
+
+	priv->rstc = devm_reset_control_get_exclusive(dev, NULL);
+	if (!IS_ERR(priv->rstc))
+		reset_control_deassert(priv->rstc);
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	priv->miscellaneous =
+	    devm_ioremap(dev, wdt_res->start, resource_size(wdt_res));
+	if (IS_ERR(priv->miscellaneous))
+		return PTR_ERR(priv->miscellaneous);
+
+	priv->wdev.info = &sp_wdt_info;
+	priv->wdev.ops = &sp_wdt_ops;
+	priv->wdev.timeout = SP_WDT_MAX_TIMEOUT;
+	priv->wdev.max_timeout = SP_WDT_MAX_TIMEOUT;
+	priv->wdev.min_timeout = SP_WDT_MIN_TIMEOUT;
+	priv->wdev.parent = dev;
+
+	watchdog_set_drvdata(&priv->wdev, priv);
+	sp_wdt_hw_init(&priv->wdev);
+
+	watchdog_init_timeout(&priv->wdev, timeout, dev);
+	watchdog_set_nowayout(&priv->wdev, nowayout);
+	watchdog_stop_on_reboot(&priv->wdev);
+
+	err = devm_watchdog_register_device(dev, &priv->wdev);
+	if (unlikely(err))
+		return err;
+
+	dev_info(dev, "Watchdog enabled (timeout=%d sec%s.)\n",
+		 priv->wdev.timeout, nowayout ? ", nowayout" : "");
+
+	return 0;
+}
+
+static int sp_wdt_remove(struct platform_device *pdev)
+{
+	struct sp_wdt_priv *priv = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&priv->wdev);
+
+	reset_control_assert(priv->rstc);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static const struct of_device_id sp_wdt_of_match[] = {
+	{.compatible = "sunplus,sp7021-wdt", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sp_wdt_of_match);
+
+static int __maybe_unused sp_wdt_suspend(struct device *dev)
+{
+	struct sp_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (watchdog_active(&priv->wdev))
+		sp_wdt_stop(&priv->wdev);
+
+	reset_control_assert(priv->rstc);
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int __maybe_unused sp_wdt_resume(struct device *dev)
+{
+	struct sp_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (watchdog_active(&priv->wdev))
+		sp_wdt_start(&priv->wdev);
+
+	reset_control_deassert(priv->rstc);
+	clk_prepare_enable(priv->clk);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(sp_wdt_pm_ops, sp_wdt_suspend, sp_wdt_resume);
+
+static struct platform_driver sp_wdt_driver = {
+	.probe = sp_wdt_probe,
+	.remove = sp_wdt_remove,
+	.driver = {
+		   .name = DEVICE_NAME,
+		   .of_match_table = sp_wdt_of_match,
+		   .pm = &sp_wdt_pm_ops,
+	},
+};
+
+module_platform_driver(sp_wdt_driver);
+
+MODULE_AUTHOR("Xiantao Hu <xt.hu@cqplus1.com>");
+MODULE_DESCRIPTION("Sunplus Watchdog Timer Driver");
+MODULE_LICENSE("GPL v2");