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@xxxxxxx>
Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
CC: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
---
drivers/acpi/scan.c | 42 ++++++++++++++++++++++++++++++++++++++++++
include/acpi/acpi_bus.h | 3 +++
include/linux/acpi.h | 10 ++++++++++
3 files changed, 55 insertions(+)
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 01136b8..3be213e 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1328,6 +1328,48 @@ 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;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 5a42204..13417d0 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -567,6 +567,9 @@ struct acpi_pci_root {
/* helper */
+bool acpi_dma_supported(struct acpi_device *adev);
+enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev);
+
struct acpi_device *acpi_find_child_device(struct acpi_device *parent,
u64 address, bool check_children);
int acpi_is_root_bridge(acpi_handle);
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index dd39202..c47892c 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -569,6 +569,16 @@ static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent)
return false;
}
+static inline bool acpi_dma_supported(struct acpi_device *adev)
+{
+ return false;
+}
+
+static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
+{
+ return DEV_DMA_NOT_SUPPORTED;
+}
+
#define ACPI_PTR(_ptr) (NULL)
#endif /* !CONFIG_ACPI */
--
2.1.0
--
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