linux-kernel - [PATCH v2 5/9] watchdog: rzv2h_wdt: Add support for configurable count clock source

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Message-ID: <20250729155915.67758-6-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Tue, 29 Jul 2025 16:59:11 +0100
From: Prabhakar <prabhakar.csengg@...il.com>
To: Wim Van Sebroeck <wim@...ux-watchdog.org>,
	Guenter Roeck <linux@...ck-us.net>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: linux-watchdog@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	Prabhakar <prabhakar.csengg@...il.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH v2 5/9] watchdog: rzv2h_wdt: Add support for configurable count clock source

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

Add support for selecting the count clock source used by the watchdog
timer. The RZ/V2H(P) SoC uses the LOCO as the count source, whereas on
RZ/T2H and RZ/N2H SoCs, the count source is the peripheral clock (PCLKL).

Introduce a `count_source` field in the SoC-specific data structure and
refactor the clock rate selection logic accordingly. This prepares the
driver for supporting the RZ/T2H and RZ/N2H SoCs, which differ in their
watchdog clocking architecture from RZ/V2H(P).

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
v1->v2:
- No changes.
---
 drivers/watchdog/rzv2h_wdt.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index baf9d64510b9..cb584ac5860f 100644
--- a/drivers/watchdog/rzv2h_wdt.c
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -44,10 +44,16 @@ module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+enum rzv2h_wdt_count_source {
+	COUNT_SOURCE_LOCO,
+	COUNT_SOURCE_PCLK,
+};
+
 struct rzv2h_of_data {
 	u8 cks_min;
 	u8 cks_max;
 	u16 cks_div;
+	enum rzv2h_wdt_count_source count_source;
 };
 
 struct rzv2h_wdt_priv {
@@ -213,6 +219,7 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rzv2h_wdt_priv *priv;
+	struct clk *count_clk;
 	int ret;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
@@ -238,8 +245,18 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(priv->rstc),
 				     "failed to get cpg reset");
 
+	switch (priv->of_data->count_source) {
+	case COUNT_SOURCE_LOCO:
+		count_clk = priv->oscclk;
+		break;
+	case COUNT_SOURCE_PCLK:
+		count_clk = priv->pclk;
+		break;
+	default:
+		return dev_err_probe(dev, -EINVAL, "Invalid count source\n");
+	}
 	priv->wdev.max_hw_heartbeat_ms = (MILLI * MAX_TIMEOUT_CYCLES * priv->of_data->cks_div) /
-					 clk_get_rate(priv->oscclk);
+					 clk_get_rate(count_clk);
 	dev_dbg(dev, "max hw timeout of %dms\n", priv->wdev.max_hw_heartbeat_ms);
 
 	ret = devm_pm_runtime_enable(dev);
@@ -266,6 +283,7 @@ static const struct rzv2h_of_data rzv2h_wdt_of_data = {
 	.cks_min = WDTCR_CKS_CLK_1,
 	.cks_max = WDTCR_CKS_CLK_256,
 	.cks_div = 256,
+	.count_source = COUNT_SOURCE_LOCO,
 };
 
 static const struct of_device_id rzv2h_wdt_ids[] = {
-- 
2.50.1