ACPI / scan: Parse _CCA and setup device coherency

[firefly-linux-kernel-4.4.55.git] / include / acpi / acpi_bus.h

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index da079976971fe1afd234cec0cad2b4e231f40b05..54df54d00cd2add5125cf781b6d57f83236d4651 100644 (file)
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -209,7 +209,9 @@ struct acpi_device_flags {
        u32 hotplug_notify:1;
        u32 is_dock_station:1;
        u32 of_compatible_ok:1;
-       u32 reserved:22;
+       u32 coherent_dma:1;
+       u32 cca_seen:1;
+       u32 reserved:20;
 };
 
 /* File System */
@@ -381,6 +383,39 @@ struct acpi_device {
        void (*remove)(struct acpi_device *);
 };
 
+static inline bool acpi_check_dma(struct acpi_device *adev, bool *coherent)
+{
+       bool ret = false;
+
+       if (!adev)
+               return ret;
+
+       /**
+        * Currently, we only support _CCA=1 (i.e. coherent_dma=1)
+        * This should be equivalent to specifyig dma-coherent for
+        * a device in OF.
+        *
+        * For the case when _CCA=0 (i.e. coherent_dma=0 && cca_seen=1),
+        * There are two cases:
+        * case 1. Do not support and disable DMA.
+        * case 2. Support but rely on arch-specific cache maintenance for
+        *         non-coherence DMA operations.
+        * Currently, we implement case 1 above.
+        *
+        * For the case when _CCA is missing (i.e. cca_seen=0) and
+        * platform specifies ACPI_CCA_REQUIRED, we do not support DMA,
+        * and fallback to arch-specific default handling.
+        *
+        * See acpi_init_coherency() for more info.
+        */
+       if (adev->flags.coherent_dma) {
+               ret = true;
+               if (coherent)
+                       *coherent = adev->flags.coherent_dma;
+       }
+       return ret;
+}
+
 static inline bool is_acpi_node(struct fwnode_handle *fwnode)
 {
        return fwnode && fwnode->type == FWNODE_ACPI;