Prepare for adding support for the Renesas RZ/V2H SoC RTC IP by making the
driver configuration selectable via OF match data.

For RZ/V2H RTC, the maximum periodic interrupt frequency is 128Hz instead
of 256Hz, so add this info to a SoC-specific struct and retrieve it
during probe.

Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
---
v2 changes: none

 drivers/rtc/rtc-renesas-rtca3.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-renesas-rtca3.c b/drivers/rtc/rtc-renesas-rtca3.c
index ab816bdf0d77..90dda04fad33 100644
--- a/drivers/rtc/rtc-renesas-rtca3.c
+++ b/drivers/rtc/rtc-renesas-rtca3.c
@@ -101,6 +101,15 @@ enum rtca3_alrm_set_step {
 	RTCA3_ALRM_SSTEP_INIT = 3,
 };
 
+/**
+ * struct rtca3_of_data - OF data for RTCA3
+ *
+ * @max_periodic_irq_freq: maximum periodic interrupt frequency
+ */
+struct rtca3_of_data {
+	int max_periodic_irq_freq;
+};
+
 /**
  * struct rtca3_ppb_per_cycle - PPB per cycle
  * @ten_sec: PPB per cycle in 10 seconds adjutment mode
@@ -709,6 +718,7 @@ static void rtca3_action(void *data)
 
 static int rtca3_probe(struct platform_device *pdev)
 {
+	const struct rtca3_of_data *of_data;
 	struct device *dev = &pdev->dev;
 	struct rtca3_priv *priv;
 	struct clk *clk;
@@ -718,6 +728,8 @@ static int rtca3_probe(struct platform_device *pdev)
 	if (!priv)
 		return -ENOMEM;
 
+	of_data = of_device_get_match_data(dev);
+
 	priv->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(priv->base))
 		return PTR_ERR(priv->base);
@@ -772,7 +784,7 @@ static int rtca3_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->rtc_dev);
 
 	priv->rtc_dev->ops = &rtca3_ops;
-	priv->rtc_dev->max_user_freq = 256;
+	priv->rtc_dev->max_user_freq = of_data->max_periodic_irq_freq;
 	priv->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
 	priv->rtc_dev->range_max = RTC_TIMESTAMP_END_2099;
 
@@ -875,8 +887,12 @@ static int rtca3_resume(struct device *dev)
 
 static DEFINE_SIMPLE_DEV_PM_OPS(rtca3_pm_ops, rtca3_suspend, rtca3_resume);
 
+static const struct rtca3_of_data rtca3_of_data = {
+	.max_periodic_irq_freq = 256,
+};
+
 static const struct of_device_id rtca3_of_match[] = {
-	{ .compatible = "renesas,rz-rtca3", },
+	{ .compatible = "renesas,rz-rtca3", .data = &rtca3_of_data },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, rtca3_of_match);
-- 
2.51.0

Hello,

Since the RTC will never be used for PIE (we are using hrtimer), I guess
this patch is not necessary, instead, you could simply stop setting
max_user_freq.

On 21/10/2025 08:07:02+0000, Ovidiu Panait wrote:
> Prepare for adding support for the Renesas RZ/V2H SoC RTC IP by making the
> driver configuration selectable via OF match data.
> 
> For RZ/V2H RTC, the maximum periodic interrupt frequency is 128Hz instead
> of 256Hz, so add this info to a SoC-specific struct and retrieve it
> during probe.
> 
> Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@renesas.com>
> ---
> v2 changes: none
> 
>  drivers/rtc/rtc-renesas-rtca3.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-renesas-rtca3.c b/drivers/rtc/rtc-renesas-rtca3.c
> index ab816bdf0d77..90dda04fad33 100644
> --- a/drivers/rtc/rtc-renesas-rtca3.c
> +++ b/drivers/rtc/rtc-renesas-rtca3.c
> @@ -101,6 +101,15 @@ enum rtca3_alrm_set_step {
>  	RTCA3_ALRM_SSTEP_INIT = 3,
>  };
>  
> +/**
> + * struct rtca3_of_data - OF data for RTCA3
> + *
> + * @max_periodic_irq_freq: maximum periodic interrupt frequency
> + */
> +struct rtca3_of_data {
> +	int max_periodic_irq_freq;
> +};
> +
>  /**
>   * struct rtca3_ppb_per_cycle - PPB per cycle
>   * @ten_sec: PPB per cycle in 10 seconds adjutment mode
> @@ -709,6 +718,7 @@ static void rtca3_action(void *data)
>  
>  static int rtca3_probe(struct platform_device *pdev)
>  {
> +	const struct rtca3_of_data *of_data;
>  	struct device *dev = &pdev->dev;
>  	struct rtca3_priv *priv;
>  	struct clk *clk;
> @@ -718,6 +728,8 @@ static int rtca3_probe(struct platform_device *pdev)
>  	if (!priv)
>  		return -ENOMEM;
>  
> +	of_data = of_device_get_match_data(dev);
> +
>  	priv->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(priv->base))
>  		return PTR_ERR(priv->base);
> @@ -772,7 +784,7 @@ static int rtca3_probe(struct platform_device *pdev)
>  		return PTR_ERR(priv->rtc_dev);
>  
>  	priv->rtc_dev->ops = &rtca3_ops;
> -	priv->rtc_dev->max_user_freq = 256;
> +	priv->rtc_dev->max_user_freq = of_data->max_periodic_irq_freq;
>  	priv->rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_2000;
>  	priv->rtc_dev->range_max = RTC_TIMESTAMP_END_2099;
>  
> @@ -875,8 +887,12 @@ static int rtca3_resume(struct device *dev)
>  
>  static DEFINE_SIMPLE_DEV_PM_OPS(rtca3_pm_ops, rtca3_suspend, rtca3_resume);
>  
> +static const struct rtca3_of_data rtca3_of_data = {
> +	.max_periodic_irq_freq = 256,
> +};
> +
>  static const struct of_device_id rtca3_of_match[] = {
> -	{ .compatible = "renesas,rz-rtca3", },
> +	{ .compatible = "renesas,rz-rtca3", .data = &rtca3_of_data },
>  	{ /* sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, rtca3_of_match);
> -- 
> 2.51.0
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com