[PATCH v3 2/3] watchdog: rzv2h: Convert WDTDCR handling to regmap

[Prabhakar]

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

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 <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
v2->v3:
- Dropped unwinding changes to patch#1.
- Set use_raw_spinlock to true in regmap config as certain watchdog operations
  runs in an atomic panic context.
---
 drivers/watchdog/rzv2h_wdt.c | 37 ++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index b770226f785e..cf28caef31e8 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;
@@ -91,20 +92,12 @@ static int rzv2h_wdt_ping(struct watchdog_device *wdev)
 
 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 0;
+	return regmap_set_bits(priv->wdtdcr_regmap, WDTDCR, WDTDCR_WDTSTOPCTRL);
 }
 
 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 0;
+	return regmap_clear_bits(priv->wdtdcr_regmap, WDTDCR, WDTDCR_WDTSTOPCTRL);
 }
 
 static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
@@ -280,14 +273,30 @@ 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,
+	.use_raw_spinlock = 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)
-- 
2.43.0