ACPI: Centralized processing of ACPI device resources

Currently, whoever wants to use ACPI device resources has to call
acpi_walk_resources() to browse the buffer returned by the _CRS
method for the given device and create filters passed to that
routine to apply to the individual resource items.  This generally
is cumbersome, time-consuming and inefficient.  Moreover, it may
be problematic if resource conflicts need to be resolved, because
the different users of _CRS will need to do that in a consistent
way.  However, if there are resource conflicts, the ACPI core
should be able to resolve them centrally instead of relying on
various users of acpi_walk_resources() to handle them correctly
together.

For this reason, introduce a new function, acpi_dev_get_resources(),
that can be used by subsystems to obtain a list of struct resource
objects corresponding to the ACPI device resources returned by
_CRS and, if necessary, to apply additional preprocessing routine
to the ACPI resources before converting them to the struct resource
format.

Make the ACPI code that creates platform device objects use
acpi_dev_get_resources() for resource processing instead of executing
acpi_walk_resources() twice by itself, which causes it to be much
more straightforward and easier to follow.

In the future, acpi_dev_get_resources() can be extended to meet
the needs of the ACPI PNP subsystem and other users of _CRS in
the kernel.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 16fcaf8dad3d..32fbc4e73a56 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -261,6 +261,16 @@ unsigned long acpi_dev_irq_flags(u8 triggering, u8 polarity, u8 shareable);
 bool acpi_dev_resource_interrupt(struct acpi_resource *ares, int index,
 				 struct resource *res);
 
+struct resource_list_entry {
+	struct list_head node;
+	struct resource res;
+};
+
+void acpi_dev_free_resource_list(struct list_head *list);
+int acpi_dev_get_resources(struct acpi_device *adev, struct list_head *list,
+			   int (*preproc)(struct acpi_resource *, void *),
+			   void *preproc_data);
+
 int acpi_check_resource_conflict(const struct resource *res);
 
 int acpi_check_region(resource_size_t start, resource_size_t n,