ACPI: Introduce DMA ranges parsing

Some devices have limited addressing capabilities and cannot
reference the whole memory address space while carrying out DMA
operations (eg some devices with bus address bits range smaller than
system bus - which prevents them from using bus addresses that are
otherwise valid for the system).

The ACPI _DMA object allows bus devices to define the DMA window that is
actually addressable by devices that sit upstream the bus, therefore
providing a means to parse and initialize the devices DMA masks and
addressable DMA range size.

By relying on the generic ACPI kernel layer to retrieve and parse
resources, introduce ACPI core code to parse the _DMA object.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Nate Watterson <nwatters@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/acpi/resource.c b/drivers/acpi/resource.c
index 93f1b5ce89b9..d85e010ee2cc 100644
--- a/drivers/acpi/resource.c
+++ b/drivers/acpi/resource.c
@@ -635,6 +635,41 @@ int acpi_dev_get_resources(struct acpi_device *adev, struct list_head *list,
 }
 EXPORT_SYMBOL_GPL(acpi_dev_get_resources);
 
+static int is_memory(struct acpi_resource *ares, void *not_used)
+{
+	struct resource_win win;
+	struct resource *res = &win.res;
+
+	memset(&win, 0, sizeof(win));
+
+	return !(acpi_dev_resource_memory(ares, res)
+	       || acpi_dev_resource_address_space(ares, &win)
+	       || acpi_dev_resource_ext_address_space(ares, &win));
+}
+
+/**
+ * acpi_dev_get_dma_resources - Get current DMA resources of a device.
+ * @adev: ACPI device node to get the resources for.
+ * @list: Head of the resultant list of resources (must be empty).
+ *
+ * Evaluate the _DMA method for the given device node and process its
+ * output.
+ *
+ * The resultant struct resource objects are put on the list pointed to
+ * by @list, that must be empty initially, as members of struct
+ * resource_entry objects.  Callers of this routine should use
+ * %acpi_dev_free_resource_list() to free that list.
+ *
+ * The number of resources in the output list is returned on success,
+ * an error code reflecting the error condition is returned otherwise.
+ */
+int acpi_dev_get_dma_resources(struct acpi_device *adev, struct list_head *list)
+{
+	return __acpi_dev_get_resources(adev, list, is_memory, NULL,
+					METHOD_NAME__DMA);
+}
+EXPORT_SYMBOL_GPL(acpi_dev_get_dma_resources);
+
 /**
  * acpi_dev_filter_resource_type - Filter ACPI resource according to resource
  *				   types