linux-kernel - Re: [PATCH v3 04/15] can: grcan: Add clock handling

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Message-ID: <20260123-astonishing-swine-from-mars-0f9b52-mkl@pengutronix.de>
Date: Fri, 23 Jan 2026 14:44:31 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Arun Muthusamy <arun.muthusamy@...sler.com>
Cc: robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	mailhol@...nel.org, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-can@...r.kernel.org, Daniel Hellstrom <daniel@...sler.com>
Subject: Re: [PATCH v3 04/15] can: grcan: Add clock handling

On 22.01.2026 13:10:27, Arun Muthusamy wrote:
> From: Daniel Hellstrom <daniel@...sler.com>
>
> Add clock handling and add error messages for missing 'freq' DT property.
>
> Signed-off-by: Daniel Hellstrom <daniel@...sler.com>
> Signed-off-by: Arun Muthusamy <arun.muthusamy@...sler.com>
> ---
>  drivers/net/can/grcan.c | 19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c
> index 3b1b09943436..538a9b4f82ab 100644
> --- a/drivers/net/can/grcan.c
> +++ b/drivers/net/can/grcan.c
> @@ -34,7 +34,7 @@
>  #include <linux/spinlock.h>
>  #include <linux/of.h>
>  #include <linux/of_irq.h>
> -
> +#include <linux/clk.h>
>  #include <linux/dma-mapping.h>
>
>  #define DRV_NAME	"grcan"
> @@ -1644,6 +1644,7 @@ static int grcan_probe(struct platform_device *ofdev)
>  {
>  	struct device_node *np = ofdev->dev.of_node;
>  	struct device_node *sysid_parent;
> +	struct clk *clk;
>  	u32 sysid, ambafreq;
>  	int irq, err;
>  	void __iomem *base;
> @@ -1663,8 +1664,20 @@ static int grcan_probe(struct platform_device *ofdev)
>
>  	err = of_property_read_u32(np, "freq", &ambafreq);
>  	if (err) {
> -		dev_err(&ofdev->dev, "unable to fetch \"freq\" property\n");
> -		goto exit_error;
> +		clk = devm_clk_get(&ofdev->dev, NULL);
> +		if (IS_ERR(clk)) {
> +			dev_err_probe(&ofdev->dev, PTR_ERR(clk),
> +				      "Failed both to get \"freq\" property and clock for fallback\n");
> +			err = PTR_ERR(clk);
> +			goto exit_error;
> +		}

I think devm_clk_get() either returns an error pointer or a valid clock
pointer.

> +		if (clk) {
> +			ambafreq = clk_get_rate(clk);
> +			if (!ambafreq) {
> +				dev_err(&ofdev->dev, "Invalid or Uninitialized clock\n");
> +				return -EINVAL;
> +			}
> +		}
>  	}
>
>  	base = devm_platform_ioremap_resource(ofdev, 0);

Marc
-- 
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