Re: [RESEND PATCH] driver/perf: arm-cmn: support ACPI probe

[Ilkka Koskinen <ilkka@os.amperecomputing.com>]

Hi Jing,

On Thu, 23 Mar 2023, Jing Zhang wrote:
> ACPI companion devices call insert_resource() in platform_device_add()
> to claim the device resources. If the resources are claimed again before
> ioremap(), and the addresses of multiple resources overlap, it will
> return -BUSY, causing the driver to fail to load.
>
> For example, the CMN700 on my machine is set with two resources similar
> to CMN600, and the overlap of resource addresses makes the CMN driver
> unable to match my CMN700. The error log:

I thought that the two address ranges were only needed for CMN-600?
I guess, the specification doesn't explicitly forbid giving two ranges for 
CMN700 although the example shows just one.

>
> [  12.016837] arm-cmn ARMHC700:00: can't request region for resource [mem 0x40000000-0x4fffffff]
> [  12.028230] arm-cmn: probe of ARMHC700:00 failed with error -16
> [  12.036832] arm-cmn ARMHC700:01: can't request region for resource [mem 0x40040000000-0x4004fffffff]
> [  12.051289] arm-cmn: probe of ARMHC700:01 failed with error -16
>
> So let ACPI companion devices call arm_cmn_acpi_probe() and not claim
> resource again. In addition, the arm_cmn_acpi_probe() and
> arm_cmn_of_probe() functions are refactored to make them compatible
> with both CMN600 and CMN-ANY.
>
> Fixes: 61ec1d875812 ("perf/arm-cmn: Demarcate CMN-600 specifics")
> Signed-off-by: Jing Zhang <renyu.zj@linux.alibaba.com>
> ---
> drivers/perf/arm-cmn.c | 57 ++++++++++++++++++++++++++++++++------------------
> 1 file changed, 37 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 1deb61b..beb3b37 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -2206,7 +2206,7 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
> 	return 0;
> }
>
> -static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *cmn)
> +static int arm_cmn_acpi_probe(struct platform_device *pdev, struct arm_cmn *cmn)
> {
> 	struct resource *cfg, *root;
>
> @@ -2214,12 +2214,21 @@ static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *c
> 	if (!cfg)
> 		return -EINVAL;
>
> -	root = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> -	if (!root)
> -		return -EINVAL;
> +	/* If ACPI defines more than one resource, such as cmn-600, then there may be
> +	 * a deviation between ROOTNODEBASE and PERIPHBASE, and ROOTNODEBASE can
> +	 * be obtained from the second resource. Otherwise, it can be considered that
> +	 * ROOT NODE BASE is PERIPHBASE. This is compatible with cmn-600 and cmn-any.
> +	 */
> +	if (pdev->num_resources > 1) {
> +		root = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +		if (!root)
> +			return -EINVAL;
>
> -	if (!resource_contains(cfg, root))
> -		swap(cfg, root);
> +		if (!resource_contains(cfg, root))
> +			swap(cfg, root);
> +	} else {
> +		root = cfg;
> +	}
> 	/*
> 	 * Note that devm_ioremap_resource() is dumb and won't let the platform
> 	 * device claim cfg when the ACPI companion device has already claimed
> @@ -2227,17 +2236,30 @@ static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *c
> 	 * appropriate name, we don't really need to do it again here anyway.
> 	 */
> 	cmn->base = devm_ioremap(cmn->dev, cfg->start, resource_size(cfg));
> -	if (!cmn->base)
> -		return -ENOMEM;
> +	if (IS_ERR(cmn->base))
> +		return PTR_ERR(cmn->base);

I believe, devm_ioremap() returns NULL in case of error

Cheers, Ilkka


>
> 	return root->start - cfg->start;
> }
>
> -static int arm_cmn600_of_probe(struct device_node *np)
> +static int arm_cmn_of_probe(struct platform_device *pdev, struct arm_cmn *cmn)
> {
> 	u32 rootnode;
> +	int ret;
> +
> +	cmn->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(cmn->base))
> +		return PTR_ERR(cmn->base);
>
> -	return of_property_read_u32(np, "arm,root-node", &rootnode) ?: rootnode;
> +	/* If of_property_read_u32() return -EINVAL, it means that device tree has
> +	 * not define root-node, and root-node will return 0, which is compatible
> +	 * with cmn-600 and cmn-any.
> +	 */
> +	ret = of_property_read_u32(pdev->dev.of_node, "arm,root-node", &rootnode);
> +	if (ret == -EINVAL)
> +		return 0;
> +
> +	return rootnode;
> }
>
> static int arm_cmn_probe(struct platform_device *pdev)
> @@ -2255,16 +2277,11 @@ static int arm_cmn_probe(struct platform_device *pdev)
> 	cmn->model = (unsigned long)device_get_match_data(cmn->dev);
> 	platform_set_drvdata(pdev, cmn);
>
> -	if (cmn->model == CMN600 && has_acpi_companion(cmn->dev)) {
> -		rootnode = arm_cmn600_acpi_probe(pdev, cmn);
> -	} else {
> -		rootnode = 0;
> -		cmn->base = devm_platform_ioremap_resource(pdev, 0);
> -		if (IS_ERR(cmn->base))
> -			return PTR_ERR(cmn->base);
> -		if (cmn->model == CMN600)
> -			rootnode = arm_cmn600_of_probe(pdev->dev.of_node);
> -	}
> +	if (has_acpi_companion(cmn->dev))
> +		rootnode = arm_cmn_acpi_probe(pdev, cmn);
> +	else
> +		rootnode = arm_cmn_of_probe(pdev, cmn);
> +
> 	if (rootnode < 0)
> 		return rootnode;
>
> -- 
> 1.8.3.1
>
>