linux-kernel - Re: [PATCH 3/4] net: dsa: b53: mmap: allow passing a chip ID

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Date:   Mon, 20 Mar 2023 21:01:29 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     Álvaro Fernández Rojas <noltari@...il.com>
Cc:     f.fainelli@...il.com, andrew@...n.ch, olteanv@...il.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] net: dsa: b53: mmap: allow passing a chip ID

On Mon, Mar 20, 2023 at 04:50:23PM +0100, Álvaro Fernández Rojas wrote:
> BCM63268 SoCs require a special handling for their RGMIIs, so we should be
> able to identify them as a special BCM63xx switch.
> 
> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> ---
>  drivers/net/dsa/b53/b53_mmap.c | 32 +++++++++++++++++++++++---------
>  drivers/net/dsa/b53/b53_priv.h |  9 ++++++++-
>  2 files changed, 31 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/dsa/b53/b53_mmap.c b/drivers/net/dsa/b53/b53_mmap.c
> index 464c77e10f60..706df04b6cee 100644
> --- a/drivers/net/dsa/b53/b53_mmap.c
> +++ b/drivers/net/dsa/b53/b53_mmap.c
> @@ -248,7 +248,7 @@ static int b53_mmap_probe_of(struct platform_device *pdev,
>  		return -ENOMEM;
>  
>  	pdata->regs = mem;
> -	pdata->chip_id = BCM63XX_DEVICE_ID;
> +	pdata->chip_id = (u32)device_get_match_data(dev);

make W=1 with gcc-12 tells me:

drivers/net/dsa/b53/b53_mmap.c: In function 'b53_mmap_probe_of':
drivers/net/dsa/b53/b53_mmap.c:251:26: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
  251 |         pdata->chip_id = (u32)device_get_match_data(dev);

I don't like casts much, but looking in b53_srab.c I see what appears to be
a solution to this problem:

	 pdata->chip_id = (u32)(unsigned long)of_id->data;

>  	pdata->big_endian = of_property_read_bool(np, "big-endian");
>  
>  	of_ports = of_get_child_by_name(np, "ports");
> @@ -330,14 +330,28 @@ static void b53_mmap_shutdown(struct platform_device *pdev)
>  }
>  
>  static const struct of_device_id b53_mmap_of_table[] = {
> -	{ .compatible = "brcm,bcm3384-switch" },
> -	{ .compatible = "brcm,bcm6318-switch" },
> -	{ .compatible = "brcm,bcm6328-switch" },
> -	{ .compatible = "brcm,bcm6362-switch" },
> -	{ .compatible = "brcm,bcm6368-switch" },
> -	{ .compatible = "brcm,bcm63268-switch" },
> -	{ .compatible = "brcm,bcm63xx-switch" },
> -	{ /* sentinel */ },
> +	{
> +		.compatible = "brcm,bcm3384-switch",
> +		.data = (void *)BCM63XX_DEVICE_ID,
> +	}, {
> +		.compatible = "brcm,bcm6318-switch",
> +		.data = (void *)BCM63XX_DEVICE_ID,
> +	}, {
> +		.compatible = "brcm,bcm6328-switch",
> +		.data = (void *)BCM63XX_DEVICE_ID,
> +	}, {
> +		.compatible = "brcm,bcm6362-switch",
> +		.data = (void *)BCM63XX_DEVICE_ID,
> +	}, {
> +		.compatible = "brcm,bcm6368-switch",
> +		.data = (void *)BCM63XX_DEVICE_ID,
> +	}, {
> +		.compatible = "brcm,bcm63268-switch",
> +		.data = (void *)BCM63268_DEVICE_ID,
> +	}, {
> +		.compatible = "brcm,bcm63xx-switch",
> +		.data = (void *)BCM63XX_DEVICE_ID,
> +	}, { /* sentinel */ }

This boilerplate doesn't seem ideal.
But it does seem to follow other examples in drivers/net/dsa/

FWIIW, I might have used of_device_is_compatible() without .data.
Or only provided data for the exception case(s) and used something like this.
(*completely untested*!)

	pdata->chip_id = (u32)(unsigned long)of_id->data ? : BCM63XX_DEVICE_ID;

>  };
>  MODULE_DEVICE_TABLE(of, b53_mmap_of_table);
>  
> diff --git a/drivers/net/dsa/b53/b53_priv.h b/drivers/net/dsa/b53/b53_priv.h
> index 4cf9f540696e..a689a6950189 100644
> --- a/drivers/net/dsa/b53/b53_priv.h
> +++ b/drivers/net/dsa/b53/b53_priv.h
> @@ -70,6 +70,7 @@ enum {
>  	BCM53125_DEVICE_ID = 0x53125,
>  	BCM53128_DEVICE_ID = 0x53128,
>  	BCM63XX_DEVICE_ID = 0x6300,
> +	BCM63268_DEVICE_ID = 0x63268,
>  	BCM53010_DEVICE_ID = 0x53010,
>  	BCM53011_DEVICE_ID = 0x53011,
>  	BCM53012_DEVICE_ID = 0x53012,
> @@ -191,7 +192,13 @@ static inline int is531x5(struct b53_device *dev)
>  
>  static inline int is63xx(struct b53_device *dev)
>  {
> -	return dev->chip_id == BCM63XX_DEVICE_ID;
> +	return dev->chip_id == BCM63XX_DEVICE_ID ||
> +		dev->chip_id == BCM63268_DEVICE_ID;
> +}
> +
> +static inline int is63268(struct b53_device *dev)
> +{
> +	return dev->chip_id == BCM63268_DEVICE_ID;
>  }
>  
>  static inline int is5301x(struct b53_device *dev)
> -- 
> 2.30.2
>