ACPI / PCI: replace open-coded _DSM code with helper functions

Use helper functions to simplify _DSM related code in pci-label driver.
Also enforce more strict checks on objects returned by _DSM method.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c
index f6e01a5..f12dcd1 100644 (file)
--- a/drivers/pci/pci-label.c
+++ b/drivers/pci/pci-label.c
@@ -195,80 +195,58 @@ enum acpi_attr_enum {
 static void dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
 {
        int len;
-       len = utf16s_to_utf8s((const wchar_t *)obj->
-                             package.elements[1].string.pointer,
-                             obj->package.elements[1].string.length,
+       len = utf16s_to_utf8s((const wchar_t *)obj->string.pointer,
+                             obj->string.length,
                              UTF16_LITTLE_ENDIAN,
                              buf, PAGE_SIZE);
        buf[len] = '\n';
 }
 
 static int
-dsm_get_label(acpi_handle handle, int func,
-             struct acpi_buffer *output,
-             char *buf, enum acpi_attr_enum attribute)
+dsm_get_label(struct device *dev, char *buf, enum acpi_attr_enum attr)
 {
-       struct acpi_object_list input;
-       union acpi_object params[4];
-       union acpi_object *obj;
-       int len = 0;
-
-       int err;
-
-       input.count = 4;
-       input.pointer = params;
-       params[0].type = ACPI_TYPE_BUFFER;
-       params[0].buffer.length = sizeof(device_label_dsm_uuid);
-       params[0].buffer.pointer = (char *)device_label_dsm_uuid;
-       params[1].type = ACPI_TYPE_INTEGER;
-       params[1].integer.value = 0x02;
-       params[2].type = ACPI_TYPE_INTEGER;
-       params[2].integer.value = func;
-       params[3].type = ACPI_TYPE_PACKAGE;
-       params[3].package.count = 0;
-       params[3].package.elements = NULL;
-
-       err = acpi_evaluate_object(handle, "_DSM", &input, output);
-       if (err)
+       acpi_handle handle;
+       union acpi_object *obj, *tmp;
+       int len = -1;
+
+       handle = ACPI_HANDLE(dev);
+       if (!handle)
                return -1;
 
-       obj = (union acpi_object *)output->pointer;
-       if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2) {
-               len = obj->package.elements[0].integer.value;
+       obj = acpi_evaluate_dsm(handle, device_label_dsm_uuid, 0x2,
+                               DEVICE_LABEL_DSM, NULL);
+       if (!obj)
+               return -1;
+
+       tmp = obj->package.elements;
+       if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
+           tmp[0].type == ACPI_TYPE_INTEGER &&
+           tmp[1].type == ACPI_TYPE_STRING) {
+               len = tmp[0].integer.value;
                if (buf) {
-                       if (attribute == ACPI_ATTR_INDEX_SHOW)
+                       /*
+                        * This second string element is optional even when
+                        * this _DSM is implemented; when not implemented,
+                        * this entry must return a null string.
+                        */
+                       if (attr == ACPI_ATTR_INDEX_SHOW)
                                scnprintf(buf, PAGE_SIZE, "%llu\n",
-                               obj->package.elements[0].integer.value);
-                       else if (attribute == ACPI_ATTR_LABEL_SHOW)
-                               dsm_label_utf16s_to_utf8s(obj, buf);
-                       kfree(output->pointer);
-                       return strlen(buf);
+                               tmp->integer.value);
+                       else if (attr == ACPI_ATTR_LABEL_SHOW)
+                               dsm_label_utf16s_to_utf8s(tmp + 1, buf);
+                       len = strlen(buf) > 0 ? strlen(buf) : -1;
                }
-               kfree(output->pointer);
-               return len;
        }
 
-       kfree(output->pointer);
+       ACPI_FREE(obj);
 
-       return -1;
+       return len;
 }
 
 static bool
 device_has_dsm(struct device *dev)
 {
-       acpi_handle handle;
-       struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
-
-       handle = ACPI_HANDLE(dev);
-
-       if (!handle)
-               return FALSE;
-
-       if (dsm_get_label(handle, DEVICE_LABEL_DSM, &output, NULL,
-                         ACPI_ATTR_NONE) > 0)
-               return TRUE;
-
-       return FALSE;
+       return dsm_get_label(dev, NULL, ACPI_ATTR_NONE) > 0;
 }
 
 static umode_t
@@ -287,44 +265,13 @@ acpi_index_string_exist(struct kobject *kobj, struct attribute *attr, int n)
 static ssize_t
 acpilabel_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-       struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
-       acpi_handle handle;
-       int length;
-
-       handle = ACPI_HANDLE(dev);
-
-       if (!handle)
-               return -1;
-
-       length = dsm_get_label(handle, DEVICE_LABEL_DSM,
-                              &output, buf, ACPI_ATTR_LABEL_SHOW);
-
-       if (length < 1)
-               return -1;
-
-       return length;
+       return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
 }
 
 static ssize_t
 acpiindex_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-       struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
-       acpi_handle handle;
-       int length;
-
-       handle = ACPI_HANDLE(dev);
-
-       if (!handle)
-               return -1;
-
-       length = dsm_get_label(handle, DEVICE_LABEL_DSM,
-                              &output, buf, ACPI_ATTR_INDEX_SHOW);
-
-       if (length < 0)
-               return -1;
-
-       return length;
-
+       return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
 }
 
 static struct device_attribute acpi_attr_label = {