[PATCH v3 6/8] watchdog: rzv2h: Add syscon support for WDTDCR

[Prabhakar]

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

On RZ/T2H and RZ/N2H SoCs, the WDTDCR (WDT Debug Control Register) resides
in the second register region of the CPG/MSSR block. Since this
multi-function block is shared with other peripherals, it is exposed via a
syscon regmap interface.

Look up the SYSC regmap using the optional "renesas,sysc" property and
derive the WDTDCR offset from the watchdog instance index.

Retain the existing MMIO-based access method when the "renesas,sysc"
property is absent to preserve compatibility with existing DT's.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
---
v2->v3:
- Made use of the new "renesas,sysc" phandle-array property to access the
  WDTDCR register via the CPG/MSSR syscon node.
- Updated commit message

v1->v2:
- No change.
---
 drivers/watchdog/Kconfig     |  1 +
 drivers/watchdog/rzv2h_wdt.c | 56 +++++++++++++++++++++++++++++-------
 2 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 9f013d774897..9267fd74bfb2 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1036,6 +1036,7 @@ config RENESAS_RZV2HWDT
 	depends on ARCH_RENESAS || COMPILE_TEST
 	depends on PM || COMPILE_TEST
 	select WATCHDOG_CORE
+	select MFD_SYSCON
 	help
 	  This driver adds watchdog support for the integrated watchdogs in the
 	  Renesas RZ/{G3E,V2H(P)} SoCs. These watchdogs can be used to reset a
diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index 3c8739902ec4..58daa6b6e3e0 100644
--- a/drivers/watchdog/rzv2h_wdt.c
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -8,6 +8,7 @@
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
@@ -44,6 +45,11 @@
 
 #define WDT_DEFAULT_TIMEOUT	60U
 
+#define RZT2H_WDT_MAX_INSTANCES	6
+
+#define RZT2H_SYS_BLOCK1(n)	(BIT(16) | (0x5100 + (n) * 4))
+#define RZT2H_WDTDCR_OFFSET(n)	RZT2H_SYS_BLOCK1(n)
+
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
@@ -64,14 +70,19 @@ struct rzv2h_of_data {
 	bool wdtdcr;
 };
 
+struct rzv2h_sysc_wdtdcr {
+	struct regmap *regmap;
+	unsigned int offset;
+};
+
 struct rzv2h_wdt_priv {
 	void __iomem *base;
-	struct regmap *wdtdcr_regmap;
 	struct clk *pclk;
 	struct clk *oscclk;
 	struct reset_control *rstc;
 	struct watchdog_device wdev;
 	const struct rzv2h_of_data *of_data;
+	struct rzv2h_sysc_wdtdcr sysc;
 };
 
 static int rzv2h_wdt_ping(struct watchdog_device *wdev)
@@ -90,12 +101,16 @@ static int rzv2h_wdt_ping(struct watchdog_device *wdev)
 
 static int rzt2h_wdt_wdtdcr_count_stop(struct rzv2h_wdt_priv *priv)
 {
-	return regmap_set_bits(priv->wdtdcr_regmap, WDTDCR, WDTDCR_WDTSTOPCTRL);
+	struct rzv2h_sysc_wdtdcr *sysc = &priv->sysc;
+
+	return regmap_set_bits(sysc->regmap, sysc->offset, WDTDCR_WDTSTOPCTRL);
 }
 
 static int rzt2h_wdt_wdtdcr_count_start(struct rzv2h_wdt_priv *priv)
 {
-	return regmap_clear_bits(priv->wdtdcr_regmap, WDTDCR, WDTDCR_WDTSTOPCTRL);
+	struct rzv2h_sysc_wdtdcr *sysc = &priv->sysc;
+
+	return regmap_clear_bits(sysc->regmap, sysc->offset, WDTDCR_WDTSTOPCTRL);
 }
 
 static void rzv2h_wdt_setup(struct watchdog_device *wdev, u16 wdtcr)
@@ -281,17 +296,36 @@ static const struct regmap_config rzv2h_wdtdcr_regmap_config = {
 static int rzt2h_wdt_wdtdcr_init(struct platform_device *pdev,
 				 struct rzv2h_wdt_priv *priv)
 {
-	void __iomem *wdtdcr;
+	struct device_node *np = pdev->dev.of_node;
+	bool syscon_present = of_property_present(np, "renesas,sysc");
+	struct rzv2h_sysc_wdtdcr *sysc = &priv->sysc;
 	int ret;
 
-	wdtdcr = devm_platform_ioremap_resource(pdev, 1);
-	if (IS_ERR(wdtdcr))
-		return PTR_ERR(wdtdcr);
+	if (syscon_present) {
+		unsigned int wdt_index;
 
-	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);
+		sysc->regmap = syscon_regmap_lookup_by_phandle_args(np, "renesas,sysc",
+								    1, &wdt_index);
+		if (IS_ERR(sysc->regmap))
+			return PTR_ERR(sysc->regmap);
+
+		if (wdt_index >= RZT2H_WDT_MAX_INSTANCES)
+			return -EINVAL;
+
+		sysc->offset = RZT2H_WDTDCR_OFFSET(wdt_index);
+	} else {
+		void __iomem *wdtdcr;
+
+		wdtdcr = devm_platform_ioremap_resource(pdev, 1);
+		if (IS_ERR(wdtdcr))
+			return PTR_ERR(wdtdcr);
+
+		sysc->regmap = devm_regmap_init_mmio(&pdev->dev, wdtdcr,
+						     &rzv2h_wdtdcr_regmap_config);
+		if (IS_ERR(sysc->regmap))
+			return PTR_ERR(sysc->regmap);
+		sysc->offset = WDTDCR;
+	}
 
 	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret)
-- 
2.54.0