linux-kernel - Re: [RFC PATCH 1/6] ACPI/IORT: Set PMCG device parent

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Date:   Tue, 15 Oct 2019 10:35:38 +0800
From:   Hanjun Guo <guohanjun@...wei.com>
To:     John Garry <john.garry@...wei.com>, <lorenzo.pieralisi@....com>,
        <sudeep.holla@....com>, <robin.murphy@....com>,
        <mark.rutland@....com>, <will@...nel.org>
CC:     <shameerali.kolothum.thodi@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <iommu@...ts.linux-foundation.org>,
        <rjw@...ysocki.net>, <lenb@...nel.org>, <nleeder@...eaurora.org>,
        <linuxarm@...wei.com>
Subject: Re: [RFC PATCH 1/6] ACPI/IORT: Set PMCG device parent

Hi John,

On 2019/9/30 22:33, John Garry wrote:
> In the IORT, a PMCG node includes a node reference to its associated
> device.
> 
> Set the PMCG platform device parent device for future referencing.
> 
> For now, we only consider setting for when the associated component is an
> SMMUv3.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>  drivers/acpi/arm64/iort.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 8569b79e8b58..0b687520c3e7 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1455,7 +1455,7 @@ static __init const struct iort_dev_config *iort_get_dev_cfg(
>   * Returns: 0 on success, <0 failure

...

>   */
>  static int __init iort_add_platform_device(struct acpi_iort_node *node,
> -					   const struct iort_dev_config *ops)
> +					   const struct iort_dev_config *ops, struct device *parent)

Since you added a input for this function, could you please update
the comments of this function as well?

>  {
>  	struct fwnode_handle *fwnode;
>  	struct platform_device *pdev;
> @@ -1466,6 +1466,8 @@ static int __init iort_add_platform_device(struct acpi_iort_node *node,
>  	if (!pdev)
>  		return -ENOMEM;
>  
> +	pdev->dev.parent = parent;
> +
>  	if (ops->dev_set_proximity) {
>  		ret = ops->dev_set_proximity(&pdev->dev, node);
>  		if (ret)
> @@ -1573,6 +1575,11 @@ static void __init iort_enable_acs(struct acpi_iort_node *iort_node)
>  static inline void iort_enable_acs(struct acpi_iort_node *iort_node) { }
>  #endif
>  
> +static int iort_fwnode_match(struct device *dev, const void *fwnode)
> +{
> +	return dev->fwnode == fwnode;
> +}
> +
>  static void __init iort_init_platform_devices(void)
>  {
>  	struct acpi_iort_node *iort_node, *iort_end;
> @@ -1594,11 +1601,34 @@ static void __init iort_init_platform_devices(void)
>  				iort_table->length);
>  
>  	for (i = 0; i < iort->node_count; i++) {
> +		struct device *parent = NULL;
> +
>  		if (iort_node >= iort_end) {
>  			pr_err("iort node pointer overflows, bad table\n");
>  			return;
>  		}
>  
> +		/* Fixme: handle parent declared in IORT after PMCG */
> +		if (iort_node->type == ACPI_IORT_NODE_PMCG) {
> +			struct acpi_iort_node *iort_assoc_node;
> +			struct acpi_iort_pmcg *pmcg;
> +			u32 node_reference;
> +
> +			pmcg = (struct acpi_iort_pmcg *)iort_node->node_data;
> +
> +			node_reference = pmcg->node_reference;
> +			iort_assoc_node = ACPI_ADD_PTR(struct acpi_iort_node, iort,
> +				 node_reference);
> +
> +			if (iort_assoc_node->type == ACPI_IORT_NODE_SMMU_V3) {
> +				struct fwnode_handle *assoc_fwnode;
> +
> +				assoc_fwnode = iort_get_fwnode(iort_assoc_node);
> +
> +				parent = bus_find_device(&platform_bus_type, NULL,
> +				      assoc_fwnode, iort_fwnode_match);
> +			}
> +		}

How about using a function to include those new added code to make this
function (iort_init_platform_devices()) a bit cleaner?

>  		iort_enable_acs(iort_node);
>  
>  		ops = iort_get_dev_cfg(iort_node);
> @@ -1609,7 +1639,7 @@ static void __init iort_init_platform_devices(void)
>  
>  			iort_set_fwnode(iort_node, fwnode);
>  
> -			ret = iort_add_platform_device(iort_node, ops);
> +			ret = iort_add_platform_device(iort_node, ops, parent);

This function is called if ops is valid, so retrieve the parent
can be done before this function I think.

Thanks
Hanjun