watchdog: mtk_wdt: mt8183: Add reset controller

Add reset controller API in watchdog driver.
Besides watchdog, MTK toprgu module alsa provide sub-system (eg, audio,
camera, codec and connectivity) software reset functionality.

Signed-off-by: yong.liang <yong.liang@mediatek.com>
Signed-off-by: Jiaxin Yu <jiaxin.yu@mediatek.com>
Reviewed-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20200115085828.27791-4-yong.liang@mediatek.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/mtk_wdt.c

@@ -9,6 +9,8 @@
  * Based on sunxi_wdt.c
  */
 
+#include <dt-bindings/reset-controller/mt8183-resets.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/io.h>
@@ -16,10 +18,11 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/reset-controller.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
-#include <linux/delay.h>
 
 #define WDT_MAX_TIMEOUT		31
 #define WDT_MIN_TIMEOUT		1
@@ -44,6 +47,9 @@
 #define WDT_SWRST		0x14
 #define WDT_SWRST_KEY		0x1209
 
+#define WDT_SWSYSRST		0x18U
+#define WDT_SWSYS_RST_KEY	0x88000000
+
 #define DRV_NAME		"mtk-wdt"
 #define DRV_VERSION		"1.0"
 
@@ -53,8 +59,90 @@ static unsigned int timeout;
 struct mtk_wdt_dev {
 	struct watchdog_device wdt_dev;
 	void __iomem *wdt_base;
+	spinlock_t lock; /* protects WDT_SWSYSRST reg */
+	struct reset_controller_dev rcdev;
 };
 
+struct mtk_wdt_data {
+	int toprgu_sw_rst_num;
+};
+
+static const struct mtk_wdt_data mt8183_data = {
+	.toprgu_sw_rst_num = MT8183_TOPRGU_SW_RST_NUM,
+};
+
+static int toprgu_reset_update(struct reset_controller_dev *rcdev,
+			       unsigned long id, bool assert)
+{
+	unsigned int tmp;
+	unsigned long flags;
+	struct mtk_wdt_dev *data =
+		 container_of(rcdev, struct mtk_wdt_dev, rcdev);
+
+	spin_lock_irqsave(&data->lock, flags);
+
+	tmp = readl(data->wdt_base + WDT_SWSYSRST);
+	if (assert)
+		tmp |= BIT(id);
+	else
+		tmp &= ~BIT(id);
+	tmp |= WDT_SWSYS_RST_KEY;
+	writel(tmp, data->wdt_base + WDT_SWSYSRST);
+
+	spin_unlock_irqrestore(&data->lock, flags);
+
+	return 0;
+}
+
+static int toprgu_reset_assert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	return toprgu_reset_update(rcdev, id, true);
+}
+
+static int toprgu_reset_deassert(struct reset_controller_dev *rcdev,
+				 unsigned long id)
+{
+	return toprgu_reset_update(rcdev, id, false);
+}
+
+static int toprgu_reset(struct reset_controller_dev *rcdev,
+			unsigned long id)
+{
+	int ret;
+
+	ret = toprgu_reset_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	return toprgu_reset_deassert(rcdev, id);
+}
+
+static const struct reset_control_ops toprgu_reset_ops = {
+	.assert = toprgu_reset_assert,
+	.deassert = toprgu_reset_deassert,
+	.reset = toprgu_reset,
+};
+
+static int toprgu_register_reset_controller(struct platform_device *pdev,
+					    int rst_num)
+{
+	int ret;
+	struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
+
+	spin_lock_init(&mtk_wdt->lock);
+
+	mtk_wdt->rcdev.owner = THIS_MODULE;
+	mtk_wdt->rcdev.nr_resets = rst_num;
+	mtk_wdt->rcdev.ops = &toprgu_reset_ops;
+	mtk_wdt->rcdev.of_node = pdev->dev.of_node;
+	ret = devm_reset_controller_register(&pdev->dev, &mtk_wdt->rcdev);
+	if (ret != 0)
+		dev_err(&pdev->dev,
+			"couldn't register wdt reset controller: %d\n", ret);
+	return ret;
+}
+
 static int mtk_wdt_restart(struct watchdog_device *wdt_dev,
 			   unsigned long action, void *data)
 {
@@ -155,6 +243,7 @@ static int mtk_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct mtk_wdt_dev *mtk_wdt;
+	const struct mtk_wdt_data *wdt_data;
 	int err;
 
 	mtk_wdt = devm_kzalloc(dev, sizeof(*mtk_wdt), GFP_KERNEL);
@@ -190,6 +279,13 @@ static int mtk_wdt_probe(struct platform_device *pdev)
 	dev_info(dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)\n",
 		 mtk_wdt->wdt_dev.timeout, nowayout);
 
+	wdt_data = of_device_get_match_data(dev);
+	if (wdt_data) {
+		err = toprgu_register_reset_controller(pdev,
+						       wdt_data->toprgu_sw_rst_num);
+		if (err)
+			return err;
+	}
 	return 0;
 }
 
@@ -219,6 +315,7 @@ static int mtk_wdt_resume(struct device *dev)
 
 static const struct of_device_id mtk_wdt_dt_ids[] = {
 	{ .compatible = "mediatek,mt6589-wdt" },
+	{ .compatible = "mediatek,mt8183-wdt", .data = &mt8183_data },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, mtk_wdt_dt_ids);