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author | Suthikulpanit, Suravee <Suravee.Suthikulpanit@amd.com> | 2015-10-28 15:50:48 -0700 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-11-07 01:29:21 +0100 |
commit | b84f196d963c3159329f72ca1913b08679004a43 (patch) | |
tree | a017e66514453e0fdc5489076877d1a02a5e568a /drivers/acpi/scan.c | |
parent | 1b9863c6aa56d92126ec0d5c42eae25df52b7ca1 (diff) | |
download | linux-b84f196d963c3159329f72ca1913b08679004a43.tar.gz linux-b84f196d963c3159329f72ca1913b08679004a43.tar.bz2 linux-b84f196d963c3159329f72ca1913b08679004a43.zip |
ACPI: Adding DMA Attribute APIs for ACPI Device
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 <Suravee.Suthikulpanit@amd.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/scan.c')
-rw-r--r-- | drivers/acpi/scan.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index d1ce377db3e9..ed3d76fadccf 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -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; |