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>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index d1ce377..ed3d76f 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1308,6 +1308,48 @@
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;