ACPI / property: Allow holes in reference properties

[cascardo/linux.git] / drivers / acpi / property.c

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index f2fd3fe..03f5ec1 100644 (file)
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -468,10 +468,11 @@ static int acpi_data_get_property_array(struct acpi_device_data *data,
 }
 
 /**
- * acpi_data_get_property_reference - returns handle to the referenced object
- * @data: ACPI device data object containing the property
+ * __acpi_node_get_property_reference - returns handle to the referenced object
+ * @fwnode: Firmware node to get the property from
  * @propname: Name of the property
  * @index: Index of the reference to return
+ * @num_args: Maximum number of arguments after each reference
  * @args: Location to store the returned reference with optional arguments
  *
  * Find property with @name, verifify that it is a package containing at least
@@ -482,17 +483,40 @@ static int acpi_data_get_property_array(struct acpi_device_data *data,
  * If there's more than one reference in the property value package, @index is
  * used to select the one to return.
  *
+ * It is possible to leave holes in the property value set like in the
+ * example below:
+ *
+ * Package () {
+ *     "cs-gpios",
+ *     Package () {
+ *        ^GPIO, 19, 0, 0,
+ *        ^GPIO, 20, 0, 0,
+ *        0,
+ *        ^GPIO, 21, 0, 0,
+ *     }
+ * }
+ *
+ * Calling this function with index %2 return %-ENOENT and with index %3
+ * returns the last entry. If the property does not contain any more values
+ * %-ENODATA is returned. The NULL entry must be single integer and
+ * preferably contain value %0.
+ *
  * Return: %0 on success, negative error code on failure.
  */
-static int acpi_data_get_property_reference(struct acpi_device_data *data,
-                                           const char *propname, size_t index,
-                                           struct acpi_reference_args *args)
+int __acpi_node_get_property_reference(struct fwnode_handle *fwnode,
+       const char *propname, size_t index, size_t num_args,
+       struct acpi_reference_args *args)
 {
        const union acpi_object *element, *end;
        const union acpi_object *obj;
+       struct acpi_device_data *data;
        struct acpi_device *device;
        int ret, idx = 0;
 
+       data = acpi_device_data_of_node(fwnode);
+       if (!data)
+               return -EINVAL;
+
        ret = acpi_data_get_property(data, propname, ACPI_TYPE_ANY, &obj);
        if (ret)
                return ret;
@@ -532,59 +556,54 @@ static int acpi_data_get_property_reference(struct acpi_device_data *data,
        while (element < end) {
                u32 nargs, i;
 
-               if (element->type != ACPI_TYPE_LOCAL_REFERENCE)
-                       return -EPROTO;
-
-               ret = acpi_bus_get_device(element->reference.handle, &device);
-               if (ret)
-                       return -ENODEV;
-
-               element++;
-               nargs = 0;
-
-               /* assume following integer elements are all args */
-               for (i = 0; element + i < end; i++) {
-                       int type = element[i].type;
+               if (element->type == ACPI_TYPE_LOCAL_REFERENCE) {
+                       ret = acpi_bus_get_device(element->reference.handle,
+                                                 &device);
+                       if (ret)
+                               return -ENODEV;
+
+                       nargs = 0;
+                       element++;
+
+                       /* assume following integer elements are all args */
+                       for (i = 0; element + i < end && i < num_args; i++) {
+                               int type = element[i].type;
+
+                               if (type == ACPI_TYPE_INTEGER)
+                                       nargs++;
+                               else if (type == ACPI_TYPE_LOCAL_REFERENCE)
+                                       break;
+                               else
+                                       return -EPROTO;
+                       }
 
-                       if (type == ACPI_TYPE_INTEGER)
-                               nargs++;
-                       else if (type == ACPI_TYPE_LOCAL_REFERENCE)
-                               break;
-                       else
+                       if (nargs > MAX_ACPI_REFERENCE_ARGS)
                                return -EPROTO;
-               }
 
-               if (idx++ == index) {
-                       args->adev = device;
-                       args->nargs = nargs;
-                       for (i = 0; i < nargs; i++)
-                               args->args[i] = element[i].integer.value;
+                       if (idx == index) {
+                               args->adev = device;
+                               args->nargs = nargs;
+                               for (i = 0; i < nargs; i++)
+                                       args->args[i] = element[i].integer.value;
 
-                       return 0;
+                               return 0;
+                       }
+
+                       element += nargs;
+               } else if (element->type == ACPI_TYPE_INTEGER) {
+                       if (idx == index)
+                               return -ENOENT;
+                       element++;
+               } else {
+                       return -EPROTO;
                }
 
-               element += nargs;
+               idx++;
        }
 
-       return -EPROTO;
-}
-
-/**
- * acpi_node_get_property_reference - get a handle to the referenced object.
- * @fwnode: Firmware node to get the property from.
- * @propname: Name of the property.
- * @index: Index of the reference to return.
- * @args: Location to store the returned reference with optional arguments.
- */
-int acpi_node_get_property_reference(struct fwnode_handle *fwnode,
-                                    const char *name, size_t index,
-                                    struct acpi_reference_args *args)
-{
-       struct acpi_device_data *data = acpi_device_data_of_node(fwnode);
-
-       return data ? acpi_data_get_property_reference(data, name, index, args) : -EINVAL;
+       return -ENODATA;
 }
-EXPORT_SYMBOL_GPL(acpi_node_get_property_reference);
+EXPORT_SYMBOL_GPL(__acpi_node_get_property_reference);
 
 static int acpi_data_prop_read_single(struct acpi_device_data *data,
                                      const char *propname,