On Tuesday, May 05, 2015 10:12:05 AM 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@redhat.com Signed-off-by: Suravee Suthikulpanit Suravee.Suthikulpanit@amd.com
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
ACPI_CCA_REQUIRED maybe?
- bool
+config ACPI_SUPPORT_CCA_ZERO
I guess this means "we support devices that can DMA, but are not coherent". right?
- 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 {
Please add braces to both branches when making such changes (as per CodingStyle).
acpi_setup_device_dma(adev, &pdev->dev);
Why do we need to do that here (for the second time)?
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) +{
- 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);
Oh dear.
What about
if (adev->flags.cca_seen && (coherent || IS_ENABLED(CONFIG_ACPI_SUPPORT_CCA_ZERO))) arch_setup_dma_ops(dev, 0, 0, NULL, coherent);
I wonder how this is going to affect x86/ia64 too?
- }
+}
+static void acpi_init_coherency(struct acpi_device *adev) +{
- unsigned long long cca = 0;
- acpi_status status;
- struct acpi_device *parent = adev->parent;
- if (parent && parent->flags.cca_seen) {
/** From ACPI spec, OSPM will ignore _CCA if an ancestor* already saw one.*/adev->flags.cca_seen = 1;cca = acpi_dma_is_coherent(parent);- } else {
status = acpi_evaluate_integer(adev->handle, "_CCA",NULL, &cca);if (ACPI_SUCCESS(status)) {adev->flags.cca_seen = 1;} else if (!IS_ENABLED(CONFIG_ACPI_MUST_HAVE_CCA)) {/** If architecture does not specify that _CCA is* required for DMA-able devices (e.g. x86),* we default to _CCA=1.*/cca = 1;} else {dev_err(&adev->dev, FW_BUG"DMA is not setup due to missing _CCA.\n");}- }
- adev->flags.is_coherent = cca;
- acpi_setup_device_dma(adev, &adev->dev);
+}
void acpi_init_device_object(struct acpi_device *device, acpi_handle handle, int type, unsigned long long sta) { @@ -2155,6 +2216,7 @@ void acpi_init_device_object(struct acpi_device *device, acpi_handle handle, device->flags.visited = false; device_initialize(&device->dev); dev_set_uevent_suppress(&device->dev, true);
- acpi_init_coherency(device);
} void acpi_device_add_finalize(struct acpi_device *device) diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 8de4fa9..b804183 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -208,7 +208,9 @@ struct acpi_device_flags { u32 visited:1; u32 hotplug_notify:1; u32 is_dock_station:1;
- u32 reserved:23;
- u32 is_coherent:1;
- u32 cca_seen:1;
- u32 reserved:21;
That will conflict with a patch I've already queued up, but never mind.
}; /* File System */ @@ -380,6 +382,13 @@ struct acpi_device { void (*remove)(struct acpi_device *); }; +static inline bool acpi_dma_is_coherent(struct acpi_device *adev) +{
- return adev && adev->flags.is_coherent;
+}
+void acpi_setup_device_dma(struct acpi_device *adev, struct device *dev);
static inline bool is_acpi_node(struct fwnode_handle *fwnode) { return fwnode && fwnode->type == FWNODE_ACPI; diff --git a/include/linux/acpi.h b/include/linux/acpi.h index b10c4a6..d14e777 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -583,6 +583,11 @@ static inline int acpi_device_modalias(struct device *dev, return -ENODEV; } +static inline bool acpi_dma_is_coherent(struct acpi_device *adev) +{
- return false;
+}
#define ACPI_PTR(_ptr) (NULL) #endif /* !CONFIG_ACPI */