watchdog: Add Realtek RTD1295

Add a watchdog driver for the Realtek RTD1295 SoC.

Based on QNAP's arch/arm/mach-rtk119x/driver/rtk_watchdog.c code and
mach-rtk119x/driver/dc2vo/fpga/include/iso_reg.h register defines.
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -787,6 +787,16 @@ config UNIPHIER_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called uniphier_wdt.
 
+config RTD119X_WATCHDOG
+	bool "Realtek RTD119x/RTD129x watchdog support"
+	depends on ARCH_REALTEK || COMPILE_TEST
+	depends on OF
+	select WATCHDOG_CORE
+	default ARCH_REALTEK
+	help
+	  Say Y here to include support for the watchdog timer in
+	  Realtek RTD1295 SoCs.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT

drivers/watchdog/Makefile

@@ -88,6 +88,7 @@ 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
+obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o

drivers/watchdog/rtd119x_wdt.c

+/*
+ * Realtek RTD129x watchdog
+ *
+ * Copyright (c) 2017 Andreas Färber
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#define RTD119X_TCWCR		0x0
+#define RTD119X_TCWTR		0x4
+#define RTD119X_TCWOV		0xc
+
+#define RTD119X_TCWCR_WDEN_DISABLED		0xa5
+#define RTD119X_TCWCR_WDEN_ENABLED		0xff
+#define RTD119X_TCWCR_WDEN_MASK			0xff
+
+#define RTD119X_TCWTR_WDCLR			BIT(0)
+
+struct rtd119x_watchdog_device {
+	struct watchdog_device wdt_dev;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int rtd119x_wdt_start(struct watchdog_device *wdev)
+{
+	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
+	u32 val;
+
+	val = readl_relaxed(data->base + RTD119X_TCWCR);
+	val &= ~RTD119X_TCWCR_WDEN_MASK;
+	val |= RTD119X_TCWCR_WDEN_ENABLED;
+	writel(val, data->base + RTD119X_TCWCR);
+
+	return 0;
+}
+
+static int rtd119x_wdt_stop(struct watchdog_device *wdev)
+{
+	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
+	u32 val;
+
+	val = readl_relaxed(data->base + RTD119X_TCWCR);
+	val &= ~RTD119X_TCWCR_WDEN_MASK;
+	val |= RTD119X_TCWCR_WDEN_DISABLED;
+	writel(val, data->base + RTD119X_TCWCR);
+
+	return 0;
+}
+
+static int rtd119x_wdt_ping(struct watchdog_device *wdev)
+{
+	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
+
+	writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
+
+	return rtd119x_wdt_start(wdev);
+}
+
+static int rtd119x_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val)
+{
+	struct rtd119x_watchdog_device *data = watchdog_get_drvdata(wdev);
+
+	writel(val * clk_get_rate(data->clk), data->base + RTD119X_TCWOV);
+
+	data->wdt_dev.timeout = val;
+
+	return 0;
+}
+
+static const struct watchdog_ops rtd119x_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start		= rtd119x_wdt_start,
+	.stop		= rtd119x_wdt_stop,
+	.ping		= rtd119x_wdt_ping,
+	.set_timeout	= rtd119x_wdt_set_timeout,
+};
+
+static const struct watchdog_info rtd119x_wdt_info = {
+	.identity = "rtd119x-wdt",
+	.options = 0,
+};
+
+static const struct of_device_id rtd119x_wdt_dt_ids[] = {
+	 { .compatible = "realtek,rtd1295-watchdog" },
+	 { }
+};
+
+static int rtd119x_wdt_probe(struct platform_device *pdev)
+{
+	struct rtd119x_watchdog_device *data;
+	struct resource *res;
+	int ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->base))
+		return PTR_ERR(data->base);
+
+	data->clk = of_clk_get(pdev->dev.of_node, 0);
+	if (IS_ERR(data->clk))
+		return PTR_ERR(data->clk);
+
+	ret = clk_prepare_enable(data->clk);
+	if (ret) {
+		clk_put(data->clk);
+		return ret;
+	}
+
+	data->wdt_dev.info = &rtd119x_wdt_info;
+	data->wdt_dev.ops = &rtd119x_wdt_ops;
+	data->wdt_dev.timeout = 120;
+	data->wdt_dev.max_timeout = 0xffffffff / clk_get_rate(data->clk);
+	data->wdt_dev.min_timeout = 1;
+	data->wdt_dev.parent = &pdev->dev;
+
+	watchdog_stop_on_reboot(&data->wdt_dev);
+	watchdog_set_drvdata(&data->wdt_dev, data);
+	platform_set_drvdata(pdev, data);
+
+	writel_relaxed(RTD119X_TCWTR_WDCLR, data->base + RTD119X_TCWTR);
+	rtd119x_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
+	rtd119x_wdt_stop(&data->wdt_dev);
+
+	ret = devm_watchdog_register_device(&pdev->dev, &data->wdt_dev);
+	if (ret) {
+		clk_disable_unprepare(data->clk);
+		clk_put(data->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int rtd119x_wdt_remove(struct platform_device *pdev)
+{
+	struct rtd119x_watchdog_device *data = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&data->wdt_dev);
+
+	clk_disable_unprepare(data->clk);
+	clk_put(data->clk);
+
+	return 0;
+}
+
+static struct platform_driver rtd119x_wdt_driver = {
+	.probe = rtd119x_wdt_probe,
+	.remove = rtd119x_wdt_remove,
+	.driver = {
+		.name = "rtd1295-watchdog",
+		.of_match_table	= rtd119x_wdt_dt_ids,
+	},
+};
+builtin_platform_driver(rtd119x_wdt_driver);