[PATCH] add %P modifier to query the node name of the parent device

Events for partition devies may want to read the main block device
name to compose it's own name or read a disklabel from the main device.

SUBSYSTEM="block", KERNEL="*[1-9]", NAME="%P-p%n"
will append the partition number to the name of the main block device.

3 files changed, 55 insertions, 1 deletions

diff --git a/namedev.c b/namedev.c
index 332e2d57d8..90d988311e 100644
--- a/namedev.c
+++ b/namedev.c
@@ -183,6 +183,7 @@ static void apply_format(struct udevice *udev, char *string, size_t maxsize,
 	int slen;
 	struct sysfs_attribute *tmpattr;
 	unsigned int next_free_number;
+	struct sysfs_class_device *class_dev_parent;
 
 	pos = string;
 	while (1) {
@@ -296,6 +297,22 @@ static void apply_format(struct udevice *udev, char *string, size_t maxsize,
 				strfieldcatmax(string, temp2, maxsize);
 			}
 			break;
+		case 'P':
+			class_dev_parent = sysfs_get_classdev_parent(class_dev);
+			if (class_dev_parent != NULL) {
+				struct udevice udev_parent;
+
+				dbg("found parent '%s', get the node name", class_dev_parent->path);
+				memset(&udev_parent, 0x00, sizeof(struct udevice));
+				/* lookup the name in the udev_db with the DEVPATH of the parent */
+				strfieldcpy(udev_parent.devpath, &class_dev_parent->path[strlen(sysfs_path)]);
+				if (udev_db_get_device(&udev_parent) == 0) {
+					strfieldcatmax(string, udev_parent.name, maxsize);
+					dbg("substitute parent node name'%s'", udev_parent.name);
+				} else
+					dbg("parent not found in database");
+			}
+			break;
 		case 'N':
 			if (udev->tmp_node[0] == '\0') {
 				dbg("create temporary device node for callout");
@@ -305,6 +322,10 @@ static void apply_format(struct udevice *udev, char *string, size_t maxsize,
 			strfieldcatmax(string, udev->tmp_node, maxsize);
 			dbg("substitute temporary device node name '%s'", udev->tmp_node);
 			break;
+		case 'r':
+			strfieldcatmax(string, udev_root, maxsize);
+			dbg("substitute udev_root '%s'", udev_root);
+			break;
 		default:
 			dbg("unknown substitution type '%%%c'", c);
 			break;
diff --git a/test/udev-test.pl b/test/udev-test.pl
index fa1e4affc6..5a519ef13b 100644
--- a/test/udev-test.pl
+++ b/test/udev-test.pl
@@ -968,7 +968,7 @@ KERNEL="sda", NAME="cdrom%e"
 EOF
 	},
 	{
-		desc		=> "enumeration char test sequence (1/5 keep)",
+		desc		=> "enumeration char test sequence 1/5 (keep)",
 		subsys		=> "block",
 		devpath		=> "/block/sda",
 		exp_name	=> "cdrom",
@@ -1086,6 +1086,36 @@ EOF
 BUS="scsi", KERNEL="sda", PROGRAM="/bin/echo %p", RESULT="/block/sda" NAME="%k"
 EOF
 	},
+	{
+		desc		=> "parent node name substitution test sequence 1/2 (keep)",
+		subsys		=> "block",
+		devpath		=> "/block/sda",
+		exp_name	=> "main_device",
+		option		=> "keep",
+		conf		=> <<EOF
+BUS="scsi", KERNEL="sda", NAME="main_device"
+EOF
+	},
+	{
+		desc		=> "parent node name substitution test sequence 2/2 (clean)",
+		subsys		=> "block",
+		devpath		=> "/block/sda/sda1",
+		exp_name	=> "main_device-part-1",
+		option		=> "clean",
+		conf		=> <<EOF
+BUS="scsi", KERNEL="sda1", NAME="%P-part-1"
+EOF
+	},
+	{
+		desc		=> "udev_root substitution",
+		subsys		=> "block",
+		devpath		=> "/block/sda/sda1",
+		exp_name	=> "start-udev-root-end",
+		option		=> "clean",
+		conf		=> <<EOF
+BUS="scsi", KERNEL="sda1", NAME="start-%r-end"
+EOF
+	},
 );
 
 # set env
diff --git a/udev.8.in b/udev.8.in
index 51c55bc5a6..3fb4bdb8da 100644
--- a/udev.8.in
+++ b/udev.8.in
@@ -218,6 +218,9 @@ all remaining parts of the result string are substituted:
 The name of a created temporary device node to provide access to the
 device from a external program.
 .TP
+.B %P
+The node name of the parent device.
+.TP
 .BI %s{ filename }
 The content of a sysfs attribute.
 .TP