Re: [PATCH v2 2/8] mfd: core: redo ACPI matching of the children devices

["Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>]

On Thursday, October 01, 2015 02:20:24 PM Andy Shevchenko wrote:
> There is at least one board on the market, i.e. Intel Galileo Gen2, that uses
> _ADR to distinguish the devices under one actual device. Due to this we have to
> improve the quirk in the MFD core to handle that board.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

>From the ACPI angle:

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

> ---
>  Documentation/acpi/enumeration.txt | 11 +++++---
>  drivers/mfd/mfd-core.c             | 52 ++++++++++++++++++++++++++------------
>  include/linux/mfd/core.h           | 10 ++++++--
>  3 files changed, 52 insertions(+), 21 deletions(-)
> 
> diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
> index b731b29..a91ec5a 100644
> --- a/Documentation/acpi/enumeration.txt
> +++ b/Documentation/acpi/enumeration.txt
> @@ -347,13 +347,18 @@ For the first case, the MFD drivers do not need to do anything. The
>  resulting child platform device will have its ACPI_COMPANION() set to point
>  to the parent device.
>  
> -If the ACPI namespace has a device that we can match using an ACPI id,
> -the id should be set like:
> +If the ACPI namespace has a device that we can match using an ACPI id or ACPI
> +adr, the cell should be set like:
> +
> +	static struct mfd_cell_acpi_match my_subdevice_cell_acpi_match = {
> +		.pnpid = "XYZ0001",
> +		.adr = 0,
> +	};
>  
>  	static struct mfd_cell my_subdevice_cell = {
>  		.name = "my_subdevice",
>  		/* set the resources relative to the parent */
> -		.acpi_pnpid = "XYZ0001",
> +		.acpi_match = &my_subdevice_cell_acpi_match,
>  	};
>  
>  The ACPI id "XYZ0001" is then used to lookup an ACPI device directly under
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index c17635d..60b60dc 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -82,29 +82,49 @@ static int mfd_platform_add_cell(struct platform_device *pdev,
>  static void mfd_acpi_add_device(const struct mfd_cell *cell,
>  				struct platform_device *pdev)
>  {
> -	struct acpi_device *parent_adev;
> +	const struct mfd_cell_acpi_match *match = cell->acpi_match;
> +	struct acpi_device *parent, *child;
>  	struct acpi_device *adev;
>  
> -	parent_adev = ACPI_COMPANION(pdev->dev.parent);
> -	if (!parent_adev)
> +	parent = ACPI_COMPANION(pdev->dev.parent);
> +	if (!parent)
>  		return;
>  
>  	/*
> -	 * MFD child device gets its ACPI handle either from the ACPI
> -	 * device directly under the parent that matches the acpi_pnpid or
> -	 * it will use the parent handle if is no acpi_pnpid is given.
> +	 * MFD child device gets its ACPI handle either from the ACPI device
> +	 * directly under the parent that matches the either _HID or _CID, or
> +	 * _ADR or it will use the parent handle if is no ID is given.
> +	 *
> +	 * Note that use of _ADR is a grey area in the ACPI specification,
> +	 * though Intel Galileo Gen2 is using it to distinguish the children
> +	 * devices.
>  	 */
> -	adev = parent_adev;
> -	if (cell->acpi_pnpid) {
> -		struct acpi_device_id ids[2] = {};
> -		struct acpi_device *child_adev;
> -
> -		strlcpy(ids[0].id, cell->acpi_pnpid, sizeof(ids[0].id));
> -		list_for_each_entry(child_adev, &parent_adev->children, node)
> -			if (acpi_match_device_ids(child_adev, ids)) {
> -				adev = child_adev;
> -				break;
> +	adev = parent;
> +	if (match) {
> +		if (match->pnpid) {
> +			struct acpi_device_id ids[2] = {};
> +
> +			strlcpy(ids[0].id, match->pnpid, sizeof(ids[0].id));
> +			list_for_each_entry(child, &parent->children, node) {
> +				if (acpi_match_device_ids(child, ids)) {
> +					adev = child;
> +					break;
> +				}
> +			}
> +		} else {
> +			unsigned long long adr;
> +			acpi_status status;
> +
> +			list_for_each_entry(child, &parent->children, node) {
> +				status = acpi_evaluate_integer(child->handle,
> +							       "_ADR", NULL,
> +							       &adr);
> +				if (ACPI_SUCCESS(status) && match->adr == adr) {
> +					adev = child;
> +					break;
> +				}
>  			}
> +		}
>  	}
>  
>  	ACPI_COMPANION_SET(&pdev->dev, adev);
> diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
> index a76bc10..27dac3f 100644
> --- a/include/linux/mfd/core.h
> +++ b/include/linux/mfd/core.h
> @@ -18,6 +18,12 @@
>  
>  struct irq_domain;
>  
> +/* Matches ACPI PNP id, either _HID or _CID, or ACPI _ADR */
> +struct mfd_cell_acpi_match {
> +	const char			*pnpid;
> +	const unsigned long long	adr;
> +};
> +
>  /*
>   * This struct describes the MFD part ("cell").
>   * After registration the copy of this structure will become the platform data
> @@ -44,8 +50,8 @@ struct mfd_cell {
>  	 */
>  	const char		*of_compatible;
>  
> -	/* Matches ACPI PNP id, either _HID or _CID */
> -	const char		*acpi_pnpid;
> +	/* Matches ACPI */
> +	const struct mfd_cell_acpi_match	*acpi_match;
>  
>  	/*
>  	 * These resources can be specified relative to the parent device.
> 

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