linux-kernel - Re: [PATCH 3/9] ACPI: add struct acpi_amba_quirk for AMD pl330 specific device config

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Date:	Fri, 4 Dec 2015 13:16:19 +0000
From:	Graeme Gregory <gg@...mlogic.co.uk>
To:	Wang Hongcheng <annie.wang@....com>
Cc:	Vinod Koul <vinod.koul@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org, dmaengine@...r.kernel.org,
	iommu@...ts.linux-foundation.org, Borislav Petkov <bp@...en8.de>,
	Huang Rui <ray.huang@....com>,
	Wan Zongshun <vincent.wan@....com>, Ken Xue <ken.xue@....com>,
	Tony Li <tony.li@....com>
Subject: Re: [PATCH 3/9] ACPI: add struct acpi_amba_quirk for AMD pl330
 specific device config

On Fri, Dec 04, 2015 at 11:24:20AM +0800, Wang Hongcheng wrote:
> AMD pl330 is a UART DMA device, it shares one ACPI item with UART. So
> a platform device and an acpi device will be created according to
> AMD0020 ACPI dev. And its mem base address must have an offset. As a
> result, MULTI_ATTACHED_QUIRK and MULTI_ATTACHED_QUIRK are used.
> 
> Signed-off-by: Wang Hongcheng <annie.wang@....com>
> ---
>  drivers/acpi/acpi_amba.c | 31 +++++++++++++++++++++++----
>  drivers/acpi/acpi_apd.c  | 56 +++++++++++++++++++++++++++++++++++++-----------
>  include/linux/acpi.h     | 13 +++++++++--
>  3 files changed, 81 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
> index 4f0366a..8a5269c 100644
> --- a/drivers/acpi/acpi_amba.c
> +++ b/drivers/acpi/acpi_amba.c
> @@ -31,6 +31,8 @@ ACPI_MODULE_NAME("amba");
>   * @periphid: AMBA device periphid.
>   * @fixed_rate: Clock frequency.
>   * @pdata: Platform data specific to the device.
> + * @quirk: Specific device config, including device multiattach.
> + * and mem base offset.
>   *
>   * Check if the given @adev can be represented as an AMBA device and, if
>   * that's the case, create and register an AMBA device, populate its
> @@ -42,7 +44,8 @@ ACPI_MODULE_NAME("amba");
>  struct amba_device *acpi_create_amba_device(struct acpi_device *adev,
>  					    unsigned int periphid,
>  					    unsigned long fixed_rate,
> -					    void *pdata)
> +					    void *pdata,
> +					    struct acpi_amba_quirk *quirk)
>  {
>  	struct amba_device *amba_dev = NULL;
>  	struct device *parent;
> @@ -54,12 +57,14 @@ struct amba_device *acpi_create_amba_device(struct acpi_device *adev,
>  	unsigned int i;
>  	unsigned int irq[AMBA_NR_IRQS];
>  	struct clk *clk = ERR_PTR(-ENODEV);
> +	char amba_devname[100];
>  
>  	/*
>  	 * If the ACPI node already has a physical device attached,
> -	 * skip it.
> +	 * skip it. Except some special devices such as AMD0020 which
> +	 * needs attach physical devices two times.
>  	 */
> -	if (adev->physical_node_count)
> +	if (adev->physical_node_count && !(quirk->quirk & MULTI_ATTACHED_QUIRK))
>  		return NULL;
>  
>  	INIT_LIST_HEAD(&resource_list);
> @@ -85,7 +90,24 @@ struct amba_device *acpi_create_amba_device(struct acpi_device *adev,
>  			memcpy(resource, rentry->res, sizeof(struct resource));
>  	}
>  
> -	amba_dev = amba_device_alloc(dev_name(&adev->dev),
> +	/*
> +	 * The memory address of AMD pl330 has an offset of ACPI
> +	 * mem resource.
> +	 */
> +	if (quirk->quirk & BASE_OFFSET_QUIRK)
> +		resource->start += quirk->base_offset;
> +
> +	/*
> +	 * If the ACPI device already has a node attached. It must be
> +	 * renamed.
> +	 */
> +	if (quirk->quirk & MULTI_ATTACHED_QUIRK)
> +		sprintf(amba_devname, "%s%s", dev_name(&adev->dev), "DMA");
> +	else
> +		memcpy(amba_devname, dev_name(&adev->dev),
> +		       strlen(dev_name(&adev->dev)));
> +
> +	amba_dev = amba_device_alloc(amba_devname,
>  				     resource->start,
>  				     resource_size(resource));
>  

Isn't this basially an MFD in a rather odd fashion?

I would have though having a device which just splits the resources then
creates 2 children would be a whole lot simpler?

Graeme

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