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 <[email protected]> CC: Rafael J. Wysocki <[email protected]> --- 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 daf9fc8..78d5f02 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; diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h index 0f131d2..920b774 100644 --- a/include/acpi/acpi_bus.h +++ b/include/acpi/acpi_bus.h @@ -596,6 +596,9 @@ 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 82f56bb..6527920 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -598,6 +598,16 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
