[PATCH 2/2] watchdog: Add Watchdog Timer driver for RZ/V2H(P)

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From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

Add Watchdog Timer driver for RZ/V2H(P) SoC.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
 drivers/watchdog/Kconfig     |   8 ++
 drivers/watchdog/Makefile    |   1 +
 drivers/watchdog/rzv2h_wdt.c | 248 +++++++++++++++++++++++++++++++++++
 3 files changed, 257 insertions(+)
 create mode 100644 drivers/watchdog/rzv2h_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 85eea38dbdf4..3f7bcc10ccc2 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -938,6 +938,14 @@ config RENESAS_RZG2LWDT
 	  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 RENESAS_RZV2HWDT
+	tristate "Renesas RZ/V2H(P) 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/V2H(P) 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 2d1117564f5b..295909a1b3b9 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -86,6 +86,7 @@ obj-$(CONFIG_RENESAS_WDT) += renesas_wdt.o
 obj-$(CONFIG_RENESAS_RZAWDT) += rza_wdt.o
 obj-$(CONFIG_RENESAS_RZN1WDT) += rzn1_wdt.o
 obj-$(CONFIG_RENESAS_RZG2LWDT) += rzg2l_wdt.o
+obj-$(CONFIG_RENESAS_RZV2HWDT) += rzv2h_wdt.o
 obj-$(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/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
new file mode 100644
index 000000000000..08f97b4bab7f
--- /dev/null
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/V2H(P) WDT Watchdog Driver
+ *
+ * Copyright (C) 2024 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/units.h>
+#include <linux/watchdog.h>
+
+#define WDTRR			0x00	/* RW, 8  */
+#define WDTCR			0x02	/* RW, 16 */
+#define WDTRCR			0x06	/* RW, 8  */
+
+#define WDTCR_TOPS_1024		0x00
+#define WDTCR_TOPS_16384	0x03
+
+#define WDTCR_CKS_CLK_1		0x00
+#define WDTCR_CKS_CLK_256	0x50
+
+#define WDTCR_RPES_0		0x300
+#define WDTCR_RPES_75		0x000
+
+#define WDTCR_RPSS_25		0x00
+#define WDTCR_RPSS_100		0x3000
+
+#define WDTRCR_RSTIRQS         BIT(7)
+
+#define CLOCK_DIV_BY_256	256
+
+#define WDT_DEFAULT_TIMEOUT	60U
+
+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 rzv2h_wdt_priv {
+	void __iomem *base;
+	struct watchdog_device wdev;
+	struct reset_control *rstc;
+	unsigned long oscclk_rate;
+};
+
+static u32 rzv2h_wdt_get_cycle_usec(struct rzv2h_wdt_priv *priv,
+				    unsigned long cycle,
+				    u16 wdttime)
+{
+	int clock_division_ratio;
+	u64 timer_cycle_us;
+
+	clock_division_ratio = CLOCK_DIV_BY_256;
+
+	timer_cycle_us = clock_division_ratio * (wdttime + 1) * MICRO;
+
+	return div64_ul(timer_cycle_us, cycle);
+}
+
+static int rzv2h_wdt_ping(struct watchdog_device *wdev)
+{
+	struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	unsigned long delay;
+
+	writeb(0x0, priv->base + WDTRR);
+	writeb(0xFF, priv->base + WDTRR);
+
+	/*
+	 * Refreshing the down-counter requires up to 4 cycles
+	 * of the signal for counting
+	 */
+	delay = 4 * rzv2h_wdt_get_cycle_usec(priv, priv->oscclk_rate, 0);
+	udelay(delay);
+
+	return 0;
+}
+
+static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
+{
+	struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	writew(wdtcr, priv->base + WDTCR);
+
+	/* LSI needs RSTIRQS to be cleared */
+	writeb(readb(priv->base + WDTRCR) & ~WDTRCR_RSTIRQS, priv->base + WDTRCR);
+}
+
+static int rzv2h_wdt_start(struct watchdog_device *wdev)
+{
+	pm_runtime_get_sync(wdev->parent);
+
+	/*
+	 * WDTCR
+	 * - CKS[7:4] - Clock Division Ratio Select - 0101b: oscclk/256
+	 * - RPSS[13:12] - Window Start Position Select - 11b: 100%
+	 * - RPES[9:8] - Window End Position Select - 11b: 0%
+	 * - TOPS[1:0] - Timeout Period Select - 11b: 16384 cycles (3FFFh)
+	 */
+	rzv2h_wdt_setup(wdev, WDTCR_CKS_CLK_256 | WDTCR_RPSS_100 |
+			WDTCR_RPES_0 | WDTCR_TOPS_16384);
+
+	rzv2h_wdt_ping(wdev);
+
+	return 0;
+}
+
+static int rzv2h_wdt_stop(struct watchdog_device *wdev)
+{
+	struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	pm_runtime_put(wdev->parent);
+	reset_control_reset(priv->rstc);
+
+	return 0;
+}
+
+static const struct watchdog_info rzv2h_wdt_ident = {
+	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+	.identity = "Renesas RZ/V2H WDT Watchdog",
+};
+
+static int rzv2h_wdt_restart(struct watchdog_device *wdev,
+			     unsigned long action, void *data)
+{
+	rzv2h_wdt_stop(wdev);
+
+	pm_runtime_get_sync(wdev->parent);
+
+	/*
+	 * WDTCR
+	 * - CKS[7:4] - Clock Division Ratio Select - 0000b: oscclk/1
+	 * - RPSS[13:12] - Window Start Position Select - 00b: 25%
+	 * - RPES[9:8] - Window End Position Select - 00b: 75%
+	 * - TOPS[1:0] - Timeout Period Select - 00b: 1024 cycles (03FFh)
+	 */
+	rzv2h_wdt_setup(wdev, WDTCR_CKS_CLK_1 | WDTCR_RPSS_25 |
+			WDTCR_RPES_75 | WDTCR_TOPS_1024);
+
+	rzv2h_wdt_ping(wdev);
+
+	return 0;
+}
+
+static const struct watchdog_ops rzv2h_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = rzv2h_wdt_start,
+	.stop = rzv2h_wdt_stop,
+	.ping = rzv2h_wdt_ping,
+	.restart = rzv2h_wdt_restart,
+};
+
+static void rzv2h_wdt_reset_assert(void *data)
+{
+	struct reset_control *rstc = data;
+
+	reset_control_assert(rstc);
+}
+
+static int rzv2h_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rzv2h_wdt_priv *priv;
+	struct clk *oscclk;
+	unsigned long rate;
+	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 oscclk clock */
+	oscclk = clk_get(&pdev->dev, "oscclk");
+	if (IS_ERR(oscclk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(oscclk),
+				     "no oscclk");
+
+	priv->oscclk_rate = clk_get_rate(oscclk);
+	clk_put(oscclk);
+	if (!priv->oscclk_rate)
+		return dev_err_probe(&pdev->dev, -EINVAL, "oscclk rate is 0");
+
+	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");
+
+	ret = reset_control_deassert(priv->rstc);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to deassert");
+	ret = devm_add_action_or_reset(&pdev->dev,
+				       rzv2h_wdt_reset_assert,
+				       priv->rstc);
+	if (ret < 0)
+		return ret;
+
+	rate = priv->oscclk_rate / 256;
+	priv->wdev.max_hw_heartbeat_ms = (1000 * 16383) / rate;
+	dev_dbg(dev, "max hw timeout of %dms\n",
+		priv->wdev.max_hw_heartbeat_ms);
+
+	priv->wdev.min_timeout = 1;
+	priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
+	priv->wdev.info = &rzv2h_wdt_ident;
+	priv->wdev.ops = &rzv2h_wdt_ops;
+	priv->wdev.parent = dev;
+	watchdog_set_drvdata(&priv->wdev, priv);
+	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");
+
+	ret = devm_pm_runtime_enable(&pdev->dev);
+	if (ret)
+		return ret;
+
+	return devm_watchdog_register_device(&pdev->dev, &priv->wdev);
+}
+
+static const struct of_device_id rzv2h_wdt_ids[] = {
+	{ .compatible = "renesas,r9a09g057-wdt", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzv2h_wdt_ids);
+
+static struct platform_driver rzv2h_wdt_driver = {
+	.driver = {
+		.name = "rzv2h_wdt",
+		.of_match_table = rzv2h_wdt_ids,
+	},
+	.probe = rzv2h_wdt_probe,
+};
+module_platform_driver(rzv2h_wdt_driver);
+MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Renesas RZ/V2H(P) WDT Watchdog Driver");
-- 
2.34.1





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