[v2,3/3] watchdog: Add Watchdog Timer driver for RZ/G2L

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index bf59faeb3de1..34da309a7afd 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -895,6 +895,14 @@  config RENESAS_RZAWDT
 	  This driver adds watchdog support for the integrated watchdogs in the
 	  Renesas RZ/A SoCs. These watchdogs can be used to reset a system.
 
+config RENESAS_RZG2LWDT
+	tristate "Renesas RZ/G2L WDT Watchdog"
+	depends on ARCH_RENESAS || COMPILE_TEST
+	select WATCHDOG_CORE
+	help
+	  This driver adds watchdog support for the integrated watchdogs in the
+	  Renesas RZ/G2L SoCs. These watchdogs can be used to reset a system.
+
 config ASPEED_WATCHDOG
 	tristate "Aspeed BMC watchdog support"
 	depends on ARCH_ASPEED || COMPILE_TEST
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 1bd2d6f37c53..e7e8ce546814 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -85,6 +85,7 @@  obj-$(CONFIG_LPC18XX_WATCHDOG) += lpc18xx_wdt.o
 obj-$(CONFIG_BCM7038_WDT) += bcm7038_wdt.o
 obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
 obj-$(CONFIG_RENESAS_RZAWDT) += rza_wdt.o
+obj-$(CONFIG_RENESAS_RZG2LWDT) += rzg2l_wdt.o
 obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
 obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
 obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
new file mode 100644
index 000000000000..77f1cfc5ecf6
--- /dev/null
+++ b/drivers/watchdog/rzg2l_wdt.c
@@ -0,0 +1,255 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/G2L WDT Watchdog Driver
+ *
+ * Copyright (C) 2021 Renesas Electronics Corporation
+ */
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+#define WDTCNT		0x00
+#define WDTSET		0x04
+#define WDTTIM		0x08
+#define WDTINT		0x0C
+#define WDTCNT_WDTEN	BIT(0)
+#define WDTINT_INTDISP	BIT(0)
+
+#define WDT_DEFAULT_TIMEOUT		60U
+
+/* Setting period time register only 12 bit set in WDTSET[31:20] */
+#define WDTSET_COUNTER_MASK		(0xFFF00000)
+#define WDTSET_COUNTER_VAL(f)		((f) << 20)
+
+#define F2CYCLE_NSEC(f)			(1000000000 / (f))
+#define WDT_CYCLE_MSEC(f, wdttime)	((1024 * 1024 * (((u64)wdttime) + 1)) / \
+					 ((f) / 1000000))
+
+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 rzg2l_wdt_priv {
+	void __iomem *base;
+	struct watchdog_device wdev;
+	struct reset_control *rstc;
+	unsigned long osc_clk_rate;
+	unsigned long delay;
+};
+
+static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv)
+{
+	/* delay timer when change the setting register */
+	ndelay(priv->delay);
+}
+
+static void rzg2l_wdt_write(struct rzg2l_wdt_priv *priv, u32 val, unsigned int reg)
+{
+	if (reg == WDTSET)
+		val &= WDTSET_COUNTER_MASK;
+
+	writel_relaxed(val, priv->base + reg);
+	/* Registers other than the WDTINT is always synchronized with WDT_CLK */
+	if (reg != WDTINT)
+		rzg2l_wdt_wait_delay(priv);
+}
+
+static void rzg2l_wdt_init_timeout(struct watchdog_device *wdev)
+{
+	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	u32 time_out;
+
+	/* Clear Lapsed Time Register and clear Interrupt */
+	rzg2l_wdt_write(priv, WDTINT_INTDISP, WDTINT);
+	/* 2 consecutive overflow cycle needed to trigger reset */
+	time_out = (wdev->timeout / 2 * 1000000) / WDT_CYCLE_MSEC(priv->osc_clk_rate, 0);
+	rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(time_out), WDTSET);
+}
+
+static int rzg2l_wdt_start(struct watchdog_device *wdev)
+{
+	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	reset_control_deassert(priv->rstc);
+	pm_runtime_get_sync(wdev->parent);
+
+	/* Initialize time out */
+	rzg2l_wdt_init_timeout(wdev);
+
+	/* Initialize watchdog counter register */
+	rzg2l_wdt_write(priv, 0, WDTTIM);
+
+	/* Enable watchdog timer*/
+	rzg2l_wdt_write(priv, WDTCNT_WDTEN, WDTCNT);
+
+	return 0;
+}
+
+static int rzg2l_wdt_stop(struct watchdog_device *wdev)
+{
+	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	pm_runtime_put(wdev->parent);
+	reset_control_assert(priv->rstc);
+
+	return 0;
+}
+
+static int rzg2l_wdt_restart(struct watchdog_device *wdev,
+			     unsigned long action, void *data)
+{
+	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	/* Reset the module before we modify any register */
+	reset_control_reset(priv->rstc);
+	pm_runtime_get_sync(wdev->parent);
+
+	/* smallest counter value to reboot soon */
+	rzg2l_wdt_write(priv, WDTSET_COUNTER_VAL(1), WDTSET);
+
+	/* Enable watchdog timer*/
+	rzg2l_wdt_write(priv, WDTCNT_WDTEN, WDTCNT);
+
+	return 0;
+}
+
+static const struct watchdog_info rzg2l_wdt_ident = {
+	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+	.identity = "Renesas RZ/G2L WDT Watchdog",
+};
+
+static int rzg2l_wdt_ping(struct watchdog_device *wdev)
+{
+	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	rzg2l_wdt_write(priv, WDTINT_INTDISP, WDTINT);
+
+	return 0;
+}
+
+static const struct watchdog_ops rzg2l_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = rzg2l_wdt_start,
+	.stop = rzg2l_wdt_stop,
+	.ping = rzg2l_wdt_ping,
+	.restart = rzg2l_wdt_restart,
+};
+
+static void rzg2l_wdt_reset_assert_pm_disable_put(void *data)
+{
+	struct watchdog_device *wdev = data;
+	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	pm_runtime_put(wdev->parent);
+	pm_runtime_disable(wdev->parent);
+	reset_control_assert(priv->rstc);
+}
+
+static int rzg2l_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rzg2l_wdt_priv *priv;
+	unsigned long pclk_rate;
+	struct clk *wdt_clk;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	/* Get watchdog main clock */
+	wdt_clk = clk_get(&pdev->dev, "oscclk");
+	if (IS_ERR(wdt_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no oscclk");
+
+	priv->osc_clk_rate = clk_get_rate(wdt_clk);
+	clk_put(wdt_clk);
+	if (!priv->osc_clk_rate)
+		return dev_err_probe(&pdev->dev, -EINVAL, "oscclk rate is 0");
+
+	/* Get Peripheral clock */
+	wdt_clk = clk_get(&pdev->dev, "pclk");
+	if (IS_ERR(wdt_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(wdt_clk), "no pclk");
+
+	pclk_rate = clk_get_rate(wdt_clk);
+	clk_put(wdt_clk);
+	if (!pclk_rate)
+		return dev_err_probe(&pdev->dev, -EINVAL, "pclk rate is 0");
+
+	priv->delay = F2CYCLE_NSEC(priv->osc_clk_rate) * 6 + F2CYCLE_NSEC(pclk_rate) * 9;
+
+	priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(priv->rstc))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->rstc),
+				     "failed to get cpg reset");
+
+	reset_control_deassert(priv->rstc);
+	pm_runtime_enable(&pdev->dev);
+	ret = pm_runtime_resume_and_get(&pdev->dev);
+	if (ret < 0) {
+		dev_err(dev, "pm_runtime_resume_and_get failed ret=%pe", ERR_PTR(ret));
+		goto out_pm_get;
+	}
+
+	priv->wdev.info = &rzg2l_wdt_ident;
+	priv->wdev.ops = &rzg2l_wdt_ops;
+	priv->wdev.parent = dev;
+	priv->wdev.min_timeout = 1;
+	priv->wdev.max_timeout = WDT_CYCLE_MSEC(priv->osc_clk_rate, 0xfff);
+	priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
+
+	watchdog_set_drvdata(&priv->wdev, priv);
+	ret = devm_add_action_or_reset(&pdev->dev,
+				       rzg2l_wdt_reset_assert_pm_disable_put,
+				       &priv->wdev);
+	if (ret < 0)
+		return ret;
+
+	watchdog_set_nowayout(&priv->wdev, nowayout);
+	watchdog_stop_on_unregister(&priv->wdev);
+
+	ret = watchdog_init_timeout(&priv->wdev, 0, dev);
+	if (ret)
+		dev_warn(dev, "Specified timeout invalid, using default");
+
+	return devm_watchdog_register_device(&pdev->dev, &priv->wdev);
+
+out_pm_get:
+	pm_runtime_disable(dev);
+	reset_control_assert(priv->rstc);
+
+	return ret;
+}
+
+static const struct of_device_id rzg2l_wdt_ids[] = {
+	{ .compatible = "renesas,rzg2l-wdt", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
+
+static struct platform_driver rzg2l_wdt_driver = {
+	.driver = {
+		.name = "rzg2l_wdt",
+		.of_match_table = rzg2l_wdt_ids,
+	},
+	.probe = rzg2l_wdt_probe,
+};
+module_platform_driver(rzg2l_wdt_driver);
+
+MODULE_DESCRIPTION("Renesas RZ/G2L WDT Watchdog Driver");
+MODULE_AUTHOR("Biju Das <biju.das.jz@bp.renesas.com>");
+MODULE_LICENSE("GPL v2");