Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 27 Mar 2023 15:05:37 +0100
From:   Will Deacon <will@kernel.org>
To:     Jing Zhang <renyu.zj@linux.alibaba.com>, robin.murphy@arm.com,
        ilkka@os.amperecomputing.com
Cc:     Mark Rutland <mark.rutland@arm.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Shuai Xue <xueshuai@linux.alibaba.com>,
        Zhuo Song <zhuo.song@linux.alibaba.com>
Subject: Re: [PATCH] perf/arm-cmn: Fix and refactor device mapping resource
Message-ID: <20230327140536.GB31752@willie-the-truck>
References: <1676535470-120560-1-git-send-email-renyu.zj@linux.alibaba.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1676535470-120560-1-git-send-email-renyu.zj@linux.alibaba.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

[+Robin and Ilkka, as they contribute most to this driver]

On Thu, Feb 16, 2023 at 04:17:50PM +0800, Jing Zhang wrote:
> The devm_platform_ioremap_resource() won't let the platform device
> claim resource when the ACPI companion device has already claimed it.
> If CMN-ANY except CMN600 is ACPI companion device, it will return
> -EBUSY in devm_platform_ioremap_resource(), and the driver cannot be
> successfully installed.
> 
> So let ACPI companion device 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);
>  
>  	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
>