On 2015年05月05日 23:12, Suravee Suthikulpanit wrote:
This patch implements support for ACPI _CCA object, which is introduced in
ACPIv5.1, can be used for specifying device DMA coherency attribute.
The parsing logic traverses device namespace to parse coherency
information, and stores it in acpi_device_flags. Then uses it to call
arch_setup_dma_ops() when creating each device enumerated in DSDT
during ACPI scan.
This patch also introduces acpi_dma_is_coherent(), which provides
an interface for device drivers to check the coherency information
similarly to the of_dma_is_coherent().
Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
---
NOTE:
* Since there seem to be conflict opinions regarding how
architecture should handle _CCA=0. So, I am proposing the
CONFIG_ARCH_SUPPORT_CCA_ZERO, which can be specified by
for each architecture to define behavior of the ACPI
scanning code when _CCA=0. Let me know if this is acceptable.
drivers/acpi/Kconfig | 6 +++++
drivers/acpi/acpi_platform.c | 4 ++-
drivers/acpi/scan.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
include/acpi/acpi_bus.h | 11 +++++++-
include/linux/acpi.h | 5 ++++
5 files changed, 86 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index ab2cbb5..dd386e9 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -54,6 +54,12 @@ config ACPI_GENERIC_GSI
config ACPI_SYSTEM_POWER_STATES_SUPPORT
bool
+config ACPI_MUST_HAVE_CCA
+ bool
+
+config ACPI_SUPPORT_CCA_ZERO
+ bool
+
config ACPI_SLEEP
bool
depends on SUSPEND || HIBERNATION
diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
index 4bf7559..a6feca4 100644
--- a/drivers/acpi/acpi_platform.c
+++ b/drivers/acpi/acpi_platform.c
@@ -108,9 +108,11 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev)
if (IS_ERR(pdev))
dev_err(&adev->dev, "platform device creation failed: %ld\n",
PTR_ERR(pdev));
- else
+ else {
+ acpi_setup_device_dma(adev, &pdev->dev);
dev_dbg(&adev->dev, "created platform device %s\n",
dev_name(&pdev->dev));
+ }
kfree(resources);
return pdev;
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 849b699..ac33b29 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -11,6 +11,7 @@
#include <linux/kthread.h>
#include <linux/dmi.h>
#include <linux/nls.h>
+#include <linux/dma-mapping.h>
#include <asm/pgtable.h>
@@ -2137,6 +2138,66 @@ void acpi_free_pnp_ids(struct acpi_device_pnp *pnp)
kfree(pnp->unique_id);
}
+void acpi_setup_device_dma(struct acpi_device *adev, struct device *dev)
I aasume adev->dev in struct *adev is the same as struct device *dev
passed here, so
+{
+ int coherent = acpi_dma_is_coherent(adev);
+
+ /**
+ * Currently, we only support DMA for devices that _CCA=1
+ * since this seems to be the case on most ACPI platforms.
+ *
+ * For the case when _CCA=0 (i.e. is_coherent=0 && cca_seen=1),
+ * we would rely on arch-specific cache maintenance for
+ * non-coherence DMA operations if architecture enables
+ * CONFIG_ACPI_SUPPORT_CCA_ZERO.
+ *
+ * For the case when _CCA is missing but platform requires it
+ * (i.e. is_coherent=0 && cca_seen=0), we do not call
+ * arch_setup_dma_ops() and fallback to arch-specific default
+ * handling.
+ */
+ if (adev->flags.cca_seen) {
+ if (!coherent && !IS_ENABLED(CONFIG_ACPI_SUPPORT_CCA_ZERO))
+ return;
+ arch_setup_dma_ops(dev, 0, 0, NULL, coherent);
how about using &adev->dev here, and just pass struct acpi_device *adev
for this function?
Thanks
Hanjun
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