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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-08-27 04:36:14 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-09-15 01:47:34 +0200
commit445b0eb058f5f31c844a731cb82e7441d0d9e578 (patch)
treece7bc79930dbd23127e0126420fc5abf0fa3f3df /drivers/acpi/property.c
parentbd8191cc8a74018e255eb3efff5e02dc305a5ed1 (diff)
downloadlinux-sh-445b0eb058f5f31c844a731cb82e7441d0d9e578.tar.gz
ACPI / property: Add support for data-only subnodes
In some cases, the information expressed via device properties is hierarchical by nature. For example, the properties of a composite device consisting of multiple semi-dependent components may need to be represented in the form of a tree of property data sets corresponding to specific components of the device. Unfortunately, using ACPI device objects for this purpose turns out to be problematic, mostly due to the assumption made by some operating systems (that platform firmware generally needs to work with) that each device object in the ACPI namespace represents a device requiring a separate driver. That assumption leads to complications which reportedly are impractically difficult to overcome and a different approach is needed for the sake of interoperability. The approach implemented here is based on extending _DSD via pointers (links) to additional ACPI objects returning data packages formatted in accordance with the _DSD formatting rules defined by Section 6.2.5 of ACPI 6. Those additional objects are referred to as data-only subnodes of the device object containing the _DSD pointing to them. The links to them need to be located in a separate section of the _DSD data package following UUID dbb8e3e6-5886-4ba6-8795-1319f52a966b referred to as the Hierarchical Data Extension UUID as defined in [1]. Each of them is represented by a package of two strings. The first string in that package (the key) is regarded as the name of the data-only subnode pointed to by the link. The second string in it (the target) is expected to hold the ACPI namespace path (possibly utilizing the usual ACPI namespace search rules) of an ACPI object evaluating to a data package extending the _DSD. The device properties initialization code follows those links, creates a struct acpi_data_node object for each of them to store the data returned by the ACPI object pointed to by it and processes those data recursively (which may lead to the creation of more struct acpi_data_node objects if the returned data package contains the Hierarchical Data Extension UUID section with more links in it). All of the struct acpi_data_node objects are present until the the ACPI device object containing the _DSD with links to them is deleted and they are deleted along with that object. [1]: http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.pdf Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Diffstat (limited to 'drivers/acpi/property.c')
-rw-r--r--drivers/acpi/property.c133
1 files changed, 132 insertions, 1 deletions
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 8163b4bd7a61..17c436de376b 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -24,6 +24,115 @@ static const u8 prp_uuid[16] = {
0x14, 0xd8, 0xff, 0xda, 0xba, 0x6e, 0x8c, 0x4d,
0x8a, 0x91, 0xbc, 0x9b, 0xbf, 0x4a, 0xa3, 0x01
};
+/* ACPI _DSD data subnodes UUID: dbb8e3e6-5886-4ba6-8795-1319f52a966b */
+static const u8 ads_uuid[16] = {
+ 0xe6, 0xe3, 0xb8, 0xdb, 0x86, 0x58, 0xa6, 0x4b,
+ 0x87, 0x95, 0x13, 0x19, 0xf5, 0x2a, 0x96, 0x6b
+};
+
+static bool acpi_enumerate_nondev_subnodes(acpi_handle scope,
+ const union acpi_object *desc,
+ struct acpi_device_data *data);
+static bool acpi_extract_properties(const union acpi_object *desc,
+ struct acpi_device_data *data);
+
+static bool acpi_nondev_subnode_ok(acpi_handle scope,
+ const union acpi_object *link,
+ struct list_head *list)
+{
+ struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
+ struct acpi_data_node *dn;
+ acpi_handle handle;
+ acpi_status status;
+
+ dn = kzalloc(sizeof(*dn), GFP_KERNEL);
+ if (!dn)
+ return false;
+
+ dn->name = link->package.elements[0].string.pointer;
+ dn->fwnode.type = FWNODE_ACPI_DATA;
+ INIT_LIST_HEAD(&dn->data.subnodes);
+
+ status = acpi_get_handle(scope, link->package.elements[1].string.pointer,
+ &handle);
+ if (ACPI_FAILURE(status))
+ goto fail;
+
+ status = acpi_evaluate_object_typed(handle, NULL, NULL, &buf,
+ ACPI_TYPE_PACKAGE);
+ if (ACPI_FAILURE(status))
+ goto fail;
+
+ if (acpi_extract_properties(buf.pointer, &dn->data))
+ dn->data.pointer = buf.pointer;
+
+ if (acpi_enumerate_nondev_subnodes(scope, buf.pointer, &dn->data))
+ dn->data.pointer = buf.pointer;
+
+ if (dn->data.pointer) {
+ list_add_tail(&dn->sibling, list);
+ return true;
+ }
+
+ acpi_handle_debug(handle, "Invalid properties/subnodes data, skipping\n");
+
+ fail:
+ ACPI_FREE(buf.pointer);
+ kfree(dn);
+ return false;
+}
+
+static int acpi_add_nondev_subnodes(acpi_handle scope,
+ const union acpi_object *links,
+ struct list_head *list)
+{
+ bool ret = false;
+ int i;
+
+ for (i = 0; i < links->package.count; i++) {
+ const union acpi_object *link;
+
+ link = &links->package.elements[i];
+ /* Only two elements allowed, both must be strings. */
+ if (link->package.count == 2
+ && link->package.elements[0].type == ACPI_TYPE_STRING
+ && link->package.elements[1].type == ACPI_TYPE_STRING
+ && acpi_nondev_subnode_ok(scope, link, list))
+ ret = true;
+ }
+
+ return ret;
+}
+
+static bool acpi_enumerate_nondev_subnodes(acpi_handle scope,
+ const union acpi_object *desc,
+ struct acpi_device_data *data)
+{
+ int i;
+
+ /* Look for the ACPI data subnodes UUID. */
+ for (i = 0; i < desc->package.count; i += 2) {
+ const union acpi_object *uuid, *links;
+
+ uuid = &desc->package.elements[i];
+ links = &desc->package.elements[i + 1];
+
+ /*
+ * The first element must be a UUID and the second one must be
+ * a package.
+ */
+ if (uuid->type != ACPI_TYPE_BUFFER || uuid->buffer.length != 16
+ || links->type != ACPI_TYPE_PACKAGE)
+ break;
+
+ if (memcmp(uuid->buffer.pointer, ads_uuid, sizeof(ads_uuid)))
+ continue;
+
+ return acpi_add_nondev_subnodes(scope, links, &data->subnodes);
+ }
+
+ return false;
+}
static bool acpi_property_value_ok(const union acpi_object *value)
{
@@ -147,6 +256,8 @@ void acpi_init_properties(struct acpi_device *adev)
acpi_status status;
bool acpi_of = false;
+ INIT_LIST_HEAD(&adev->data.subnodes);
+
/*
* Check if ACPI_DT_NAMESPACE_HID is present and inthat case we fill in
* Device Tree compatible properties for this device.
@@ -167,7 +278,11 @@ void acpi_init_properties(struct acpi_device *adev)
adev->data.pointer = buf.pointer;
if (acpi_of)
acpi_init_of_compatible(adev);
- } else {
+ }
+ if (acpi_enumerate_nondev_subnodes(adev->handle, buf.pointer, &adev->data))
+ adev->data.pointer = buf.pointer;
+
+ if (!adev->data.pointer) {
acpi_handle_debug(adev->handle, "Invalid _DSD data, skipping\n");
ACPI_FREE(buf.pointer);
}
@@ -178,8 +293,24 @@ void acpi_init_properties(struct acpi_device *adev)
ACPI_DT_NAMESPACE_HID " requires 'compatible' property\n");
}
+static void acpi_destroy_nondev_subnodes(struct list_head *list)
+{
+ struct acpi_data_node *dn, *next;
+
+ if (list_empty(list))
+ return;
+
+ list_for_each_entry_safe_reverse(dn, next, list, sibling) {
+ acpi_destroy_nondev_subnodes(&dn->data.subnodes);
+ list_del(&dn->sibling);
+ ACPI_FREE((void *)dn->data.pointer);
+ kfree(dn);
+ }
+}
+
void acpi_free_properties(struct acpi_device *adev)
{
+ acpi_destroy_nondev_subnodes(&adev->data.subnodes);
ACPI_FREE((void *)adev->data.pointer);
adev->data.of_compatible = NULL;
adev->data.pointer = NULL;