On Mon, Nov 12, 2012 at 01:02:11PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> 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.
>
> For this reason, add code to the ACPI core to execute _CRS once,
> when the struct acpi_device object is created for a given device
> node, and attach a list of ACPI resources returned by _CRS to that
> object for future processing.
>
> Convert the ACPI code that creates platform device objects to using
> the new resources list instead of executing acpi_walk_resources() by
> itself, which makes it much more straightforward and easier to
> follow.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/acpi/acpi_platform.c | 90 ++++++++++++-------------------------------
> drivers/acpi/resource.c | 12 +++++
> drivers/acpi/scan.c | 56 ++++++++++++++++++++++++++
> include/acpi/acpi_bus.h | 6 ++
> include/linux/acpi.h | 1
> 5 files changed, 102 insertions(+), 63 deletions(-)
>
> Index: linux/include/acpi/acpi_bus.h
> ===================================================================
> --- linux.orig/include/acpi/acpi_bus.h
> +++ linux/include/acpi/acpi_bus.h
> @@ -259,6 +259,11 @@ struct acpi_device_physical_node {
> struct device *dev;
> };
>
> +struct acpi_resource_list_entry {
> + struct list_head node;
> + struct acpi_resource resource;
> +};
> +
> /* set maximum of physical nodes to 32 for expansibility */
> #define ACPI_MAX_PHYSICAL_NODE 32
>
> @@ -268,6 +273,7 @@ struct acpi_device {
> acpi_handle handle; /* no handle for fixed hardware */
> struct acpi_device *parent;
> struct list_head children;
> + struct list_head resources; /* Device resources. */
> struct list_head node;
> struct list_head wakeup_list;
> struct acpi_device_status status;
> Index: linux/drivers/acpi/scan.c
> ===================================================================
> --- linux.orig/drivers/acpi/scan.c
> +++ linux/drivers/acpi/scan.c
> @@ -382,6 +382,52 @@ static void acpi_device_remove_files(str
> ACPI Bus operations
> -------------------------------------------------------------------------- */
>
> +static void acpi_bus_drop_resources(struct acpi_device *adev)
> +{
> + struct acpi_resource_list_entry *entry, *s;
> +
> + list_for_each_entry_safe(entry, s, &adev->resources, node) {
> + list_del(&entry->node);
> + kfree(entry);
> + }
> +}
> +
> +static acpi_status acpi_bus_add_resource(struct acpi_resource *res,
> + void *context)
> +{
> + struct list_head *list = context;
> + struct acpi_resource_list_entry *entry;
> +
> + entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> + if (!entry)
> + return AE_NO_MEMORY;
> +
> + entry->resource = *res;
This does not work well with all resource types - specifically those that
contain pointers, like acpi_resource_gpio and acpi_resource_source.
The memory for the resources gets freed once acpi_walk_resources() is done.
> + INIT_LIST_HEAD(&entry->node);
> + list_add_tail(&entry->node, list);
> + return AE_OK;
> +}
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