[PATCH v2 1/2] watchdog: rzv2h: Convert WDTDCR handling to regmap

From: Lad Prabhakar <[email protected]>

Convert the WDTDCR register access from raw readl/writel variants over to
the regmap framework using devm_regmap_init_mmio().

This conversion serves as a preparatory refactoring step. It allows the
driver to subsequently support syscon-based system controllers natively
by passing along alternative regmap handles without forcing messy
architectural branching at runtime.

Signed-off-by: Lad Prabhakar <[email protected]>
---
v1->v2:
- Switched to use regmap_set/clear_bits()
---
 drivers/watchdog/rzv2h_wdt.c | 75 ++++++++++++++++++++++++++----------
 1 file changed, 54 insertions(+), 21 deletions(-)

diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index 3b6abb66a1da..0f951219caf8 100644
--- a/drivers/watchdog/rzv2h_wdt.c
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -12,6 +12,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/units.h>
 #include <linux/watchdog.h>
@@ -67,7 +68,7 @@ struct rzv2h_of_data {
 
 struct rzv2h_wdt_priv {
 	void __iomem *base;
-	void __iomem *wdtdcr;
+	struct regmap *wdtdcr_regmap;
 	struct clk *pclk;
 	struct clk *oscclk;
 	struct reset_control *rstc;
@@ -89,18 +90,14 @@ static int rzv2h_wdt_ping(struct watchdog_device *wdev)
 	return 0;
 }
 
-static void rzt2h_wdt_wdtdcr_count_stop(struct rzv2h_wdt_priv *priv)
+static int rzt2h_wdt_wdtdcr_count_stop(struct rzv2h_wdt_priv *priv)
 {
-	u32 reg = readl(priv->wdtdcr + WDTDCR);
-
-	writel(reg | WDTDCR_WDTSTOPCTRL, priv->wdtdcr + WDTDCR);
+	return regmap_set_bits(priv->wdtdcr_regmap, WDTDCR, WDTDCR_WDTSTOPCTRL);
 }
 
-static void rzt2h_wdt_wdtdcr_count_start(struct rzv2h_wdt_priv *priv)
+static int rzt2h_wdt_wdtdcr_count_start(struct rzv2h_wdt_priv *priv)
 {
-	u32 reg = readl(priv->wdtdcr + WDTDCR);
-
-	writel(reg & ~WDTDCR_WDTSTOPCTRL, priv->wdtdcr + WDTDCR);
+	return regmap_clear_bits(priv->wdtdcr_regmap, WDTDCR, WDTDCR_WDTSTOPCTRL);
 }
 
 static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
@@ -150,8 +147,14 @@ static int rzv2h_wdt_start(struct watchdog_device *wdev)
 	rzv2h_wdt_setup(wdev, of_data->cks_max | WDTCR_RPSS_100 |
 			WDTCR_RPES_0 | of_data->tops);
 
-	if (priv->of_data->wdtdcr)
-		rzt2h_wdt_wdtdcr_count_start(priv);
+	if (priv->of_data->wdtdcr) {
+		ret = rzt2h_wdt_wdtdcr_count_start(priv);
+		if (ret) {
+			reset_control_assert(priv->rstc);
+			pm_runtime_put(wdev->parent);
+			return ret;
+		}
+	}
 
 	/*
 	 * Down counting starts after writing the sequence 00h -> FFh to the
@@ -171,8 +174,13 @@ static int rzv2h_wdt_stop(struct watchdog_device *wdev)
 	if (ret)
 		return ret;
 
-	if (priv->of_data->wdtdcr)
-		rzt2h_wdt_wdtdcr_count_stop(priv);
+	if (priv->of_data->wdtdcr) {
+		ret = rzt2h_wdt_wdtdcr_count_stop(priv);
+		if (ret) {
+			reset_control_deassert(priv->rstc);
+			return ret;
+		}
+	}
 
 	pm_runtime_put(wdev->parent);
 
@@ -188,9 +196,10 @@ static int rzv2h_wdt_restart(struct watchdog_device *wdev,
 			     unsigned long action, void *data)
 {
 	struct rzv2h_wdt_priv *priv = watchdog_get_drvdata(wdev);
+	bool active = watchdog_active(wdev);
 	int ret;
 
-	if (!watchdog_active(wdev)) {
+	if (!active) {
 		ret = clk_enable(priv->pclk);
 		if (ret)
 			return ret;
@@ -234,8 +243,17 @@ static int rzv2h_wdt_restart(struct watchdog_device *wdev,
 	rzv2h_wdt_setup(wdev, priv->of_data->cks_min | WDTCR_RPSS_25 |
 			WDTCR_RPES_75 | WDTCR_TOPS_1024);
 
-	if (priv->of_data->wdtdcr)
-		rzt2h_wdt_wdtdcr_count_start(priv);
+	if (priv->of_data->wdtdcr) {
+		ret = rzt2h_wdt_wdtdcr_count_start(priv);
+		if (ret) {
+			if (!active) {
+				reset_control_assert(priv->rstc);
+				clk_disable(priv->oscclk);
+				clk_disable(priv->pclk);
+			}
+			return ret;
+		}
+	}
 
 	rzv2h_wdt_ping(wdev);
 
@@ -253,24 +271,39 @@ static const struct watchdog_ops rzv2h_wdt_ops = {
 	.restart = rzv2h_wdt_restart,
 };
 
+static const struct regmap_config rzv2h_wdtdcr_regmap_config = {
+	.name = "wdtdcr",
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+	.max_register = WDTDCR,
+	.fast_io = true,
+};
+
 static int rzt2h_wdt_wdtdcr_init(struct platform_device *pdev,
 				 struct rzv2h_wdt_priv *priv)
 {
+	void __iomem *wdtdcr;
 	int ret;
 
-	priv->wdtdcr = devm_platform_ioremap_resource(pdev, 1);
-	if (IS_ERR(priv->wdtdcr))
-		return PTR_ERR(priv->wdtdcr);
+	wdtdcr = devm_platform_ioremap_resource(pdev, 1);
+	if (IS_ERR(wdtdcr))
+		return PTR_ERR(wdtdcr);
+
+	priv->wdtdcr_regmap = devm_regmap_init_mmio(&pdev->dev, wdtdcr,
+						    &rzv2h_wdtdcr_regmap_config);
+	if (IS_ERR(priv->wdtdcr_regmap))
+		return PTR_ERR(priv->wdtdcr_regmap);
 
 	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret)
 		return ret;
 
-	rzt2h_wdt_wdtdcr_count_stop(priv);
+	ret = rzt2h_wdt_wdtdcr_count_stop(priv);
 
 	pm_runtime_put(&pdev->dev);
 
-	return 0;
+	return ret;
 }
 
 static int rzv2h_wdt_probe(struct platform_device *pdev)
-- 
2.54.0