[v2] Add watchdog driver support for RZ/T2H and RZ/N2H SoCs

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

Posted by Prabhakar 2 months, 1 week ago

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

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

Posted by Wolfram Sang 2 months ago

On Tue, Jul 29, 2025 at 04:59:09PM +0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.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@bp.renesas.com>

I'd think this should be merged with patch 2, but for the change itself:

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

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

Posted by Lad, Prabhakar 2 months ago

Hi Wolfram,

Thank you for the review.

On Fri, Aug 1, 2025 at 5:04 AM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
>
> On Tue, Jul 29, 2025 at 04:59:09PM +0100, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.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@bp.renesas.com>
>
> I'd think this should be merged with patch 2, but for the change itself:
>
Ok, I will squash it with patch 2/9.

> Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>

Cheers,
Prabhakar