linux-kernel - [PATCH v2 3/9] watchdog: rzv2h_wdt: Obtain CKS divider via OF data

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Message-ID: <20250729155915.67758-4-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Tue, 29 Jul 2025 16:59:09 +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 3/9] watchdog: rzv2h_wdt: Obtain CKS divider via OF data

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

Update the rzv2h_wdt driver to obtain the clock division ratio (`cks_div`)
from OF match data instead of using a hardcoded value. This allows the
driver to support SoCs where the clock divider differs from the default
value of 256.

This change is a preparatory step for supporting the RZ/T2H SoC, which
requires a divider value of 8192.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
v1->v2:
- No changes.
---
 drivers/watchdog/rzv2h_wdt.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/rzv2h_wdt.c b/drivers/watchdog/rzv2h_wdt.c
index d64d29709160..c2f39dd56687 100644
--- a/drivers/watchdog/rzv2h_wdt.c
+++ b/drivers/watchdog/rzv2h_wdt.c
@@ -36,7 +36,6 @@
 #define WDTRCR_RSTIRQS		BIT(7)
 
 #define MAX_TIMEOUT_CYCLES	16384
-#define CLOCK_DIV_BY_256	256
 
 #define WDT_DEFAULT_TIMEOUT	60U
 
@@ -48,6 +47,7 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 struct rzv2h_of_data {
 	u8 cks_min;
 	u8 cks_max;
+	u16 cks_div;
 };
 
 struct rzv2h_wdt_priv {
@@ -238,7 +238,7 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 		return dev_err_probe(dev, PTR_ERR(priv->rstc),
 				     "failed to get cpg reset");
 
-	priv->wdev.max_hw_heartbeat_ms = (MILLI * MAX_TIMEOUT_CYCLES * CLOCK_DIV_BY_256) /
+	priv->wdev.max_hw_heartbeat_ms = (MILLI * MAX_TIMEOUT_CYCLES * priv->of_data->cks_div) /
 					 clk_get_rate(priv->oscclk);
 	dev_dbg(dev, "max hw timeout of %dms\n", priv->wdev.max_hw_heartbeat_ms);
 
@@ -265,6 +265,7 @@ static int rzv2h_wdt_probe(struct platform_device *pdev)
 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,
 };
 
 static const struct of_device_id rzv2h_wdt_ids[] = {
-- 
2.50.1