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>

1 files changed, 34 insertions, 87 deletions

diff --git a/drivers/pci/pci-label.c b/drivers/pci/pci-label.c
index f6e01a500d79..f12dcd1dc208 100644
--- 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 = {