watchdog: mediatek: mt7988: add wdt support

Add support for watchdog and reset generator unit of the MediaTek
MT7988 SoC.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/c0cf5f701801cce60470853fa15f1d9dced78c4f.1700504385.git.daniel@makrotopia.orgSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/mtk_wdt.c

@@ -58,9 +58,13 @@
 #define WDT_SWSYSRST		0x18U
 #define WDT_SWSYS_RST_KEY	0x88000000
 
+#define WDT_SWSYSRST_EN		0xfc
+
 #define DRV_NAME		"mtk-wdt"
 #define DRV_VERSION		"1.0"
 
+#define MT7988_TOPRGU_SW_RST_NUM	24
+
 static bool nowayout = WATCHDOG_NOWAYOUT;
 static unsigned int timeout;
 
@@ -71,10 +75,12 @@ struct mtk_wdt_dev {
 	struct reset_controller_dev rcdev;
 	bool disable_wdt_extrst;
 	bool reset_by_toprgu;
+	bool has_swsysrst_en;
 };
 
 struct mtk_wdt_data {
 	int toprgu_sw_rst_num;
+	bool has_swsysrst_en;
 };
 
 static const struct mtk_wdt_data mt2712_data = {
@@ -89,6 +95,11 @@ static const struct mtk_wdt_data mt7986_data = {
 	.toprgu_sw_rst_num = MT7986_TOPRGU_SW_RST_NUM,
 };
 
+static const struct mtk_wdt_data mt7988_data = {
+	.toprgu_sw_rst_num = MT7988_TOPRGU_SW_RST_NUM,
+	.has_swsysrst_en = true,
+};
+
 static const struct mtk_wdt_data mt8183_data = {
 	.toprgu_sw_rst_num = MT8183_TOPRGU_SW_RST_NUM,
 };
@@ -109,6 +120,28 @@ static const struct mtk_wdt_data mt8195_data = {
 	.toprgu_sw_rst_num = MT8195_TOPRGU_SW_RST_NUM,
 };
 
+/**
+ * toprgu_reset_sw_en_unlocked() - enable/disable software control for reset bit
+ * @data: Pointer to instance of driver data.
+ * @id: Bit number identifying the reset to be enabled or disabled.
+ * @enable: If true, enable software control for that bit, disable otherwise.
+ *
+ * Context: The caller must hold lock of struct mtk_wdt_dev.
+ */
+static void toprgu_reset_sw_en_unlocked(struct mtk_wdt_dev *data,
+					unsigned long id, bool enable)
+{
+	u32 tmp;
+
+	tmp = readl(data->wdt_base + WDT_SWSYSRST_EN);
+	if (enable)
+		tmp |= BIT(id);
+	else
+		tmp &= ~BIT(id);
+
+	writel(tmp, data->wdt_base + WDT_SWSYSRST_EN);
+}
+
 static int toprgu_reset_update(struct reset_controller_dev *rcdev,
 			       unsigned long id, bool assert)
 {
@@ -119,6 +152,9 @@ static int toprgu_reset_update(struct reset_controller_dev *rcdev,
 
 	spin_lock_irqsave(&data->lock, flags);
 
+	if (assert && data->has_swsysrst_en)
+		toprgu_reset_sw_en_unlocked(data, id, true);
+
 	tmp = readl(data->wdt_base + WDT_SWSYSRST);
 	if (assert)
 		tmp |= BIT(id);
@@ -127,6 +163,9 @@ static int toprgu_reset_update(struct reset_controller_dev *rcdev,
 	tmp |= WDT_SWSYS_RST_KEY;
 	writel(tmp, data->wdt_base + WDT_SWSYSRST);
 
+	if (!assert && data->has_swsysrst_en)
+		toprgu_reset_sw_en_unlocked(data, id, false);
+
 	spin_unlock_irqrestore(&data->lock, flags);
 
 	return 0;
@@ -406,6 +445,8 @@ static int mtk_wdt_probe(struct platform_device *pdev)
 						       wdt_data->toprgu_sw_rst_num);
 		if (err)
 			return err;
+
+		mtk_wdt->has_swsysrst_en = wdt_data->has_swsysrst_en;
 	}
 
 	mtk_wdt->disable_wdt_extrst =
@@ -444,6 +485,7 @@ static const struct of_device_id mtk_wdt_dt_ids[] = {
 	{ .compatible = "mediatek,mt6589-wdt" },
 	{ .compatible = "mediatek,mt6795-wdt", .data = &mt6795_data },
 	{ .compatible = "mediatek,mt7986-wdt", .data = &mt7986_data },
+	{ .compatible = "mediatek,mt7988-wdt", .data = &mt7988_data },
 	{ .compatible = "mediatek,mt8183-wdt", .data = &mt8183_data },
 	{ .compatible = "mediatek,mt8186-wdt", .data = &mt8186_data },
 	{ .compatible = "mediatek,mt8188-wdt", .data = &mt8188_data },