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ACPI: Adding DMA Attribute APIs for ACPI Device

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Adding acpi_get_dma_attr() to query DMA attributes of ACPI devices.
It returns the enum dev_dma_attr, which communicates DMA information
more clearly. This API replaces the acpi_check_dma(), which will be
removed in subsequent patch.

This patch also provides a convenient function, acpi_dma_supported(),
to check DMA support of the specified ACPI device.

Signed-off-by: Suravee Suthikulpanit <[email protected]>
Acked-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Hanjun Guo <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
This commit is contained in:
Suthikulpanit, Suravee 2015-10-28 15:50:48 -07:00 • committed by Rafael J. Wysocki
commit b84f196d96
3 changed files with 55 additions and 0 deletions
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42
drivers/acpi/scan.c
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@ -1308,6 +1308,48 @@ void acpi_free_pnp_ids(struct acpi_device_pnp *pnp)
kfree(pnp->unique_id);
}
/**
* acpi_dma_supported - Check DMA support for the specified device.
* @adev: The pointer to acpi device
*
* Return false if DMA is not supported. Otherwise, return true
*/
bool acpi_dma_supported(struct acpi_device *adev)
{
if (!adev)
return false;
if (adev->flags.cca_seen)
return true;
/*
* Per ACPI 6.0 sec 6.2.17, assume devices can do cache-coherent
* DMA on "Intel platforms". Presumably that includes all x86 and
* ia64, and other arches will set CONFIG_ACPI_CCA_REQUIRED=y.
*/
if (!IS_ENABLED(CONFIG_ACPI_CCA_REQUIRED))
return true;
return false;
}
/**
* acpi_get_dma_attr - Check the supported DMA attr for the specified device.
* @adev: The pointer to acpi device
*
* Return enum dev_dma_attr.
*/
enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
{
if (!acpi_dma_supported(adev))
return DEV_DMA_NOT_SUPPORTED;
if (adev->flags.coherent_dma)
return DEV_DMA_COHERENT;
else
return DEV_DMA_NON_COHERENT;
}
static void acpi_init_coherency(struct acpi_device *adev)
{
unsigned long long cca = 0;