Allow specifying UBI Volumes by MTD path

In cases where the env is in an unattached UBI volume we may need
to specify the volume name via the MTD path to attach.

For this to work correctly we should first scan for any already
attached UBI devices to see if they correspond to the mtd partition
number in our configuration, if no corresponding attached mtd devices
are found we should attempt to ubiattach to the configured MTD path.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>

docs/fw_env_config.md

@@ -98,6 +98,14 @@ UBI Volume by Name Example
 | /dev/ubi0:env    |     0x0       |      0x1f000     |      0x1f000      |                   |                        |
 | /dev/ubi0:redund |     0x0       |      0x1f000     |      0x1f000      |                   |                        |
 
+UBI Volume by Name from MTD Path Example
+--------------------------
+
+| Device Name      | Device Offset | Environment Size | Flash Sector Size | Number of Sectors | Disable Lock Mechanism |
+|------------------|---------------|------------------|-------------------|-------------------|------------------------|
+| /dev/mtd0:env    |     0x0       |      0x1f000     |      0x1f000      |                   |                        |
+| /dev/mtd0:redund |     0x0       |      0x1f000     |      0x1f000      |                   |                        |
+
 Configuration File in YAML
 ==========================
 

src/uboot_env.c

@@ -43,6 +43,9 @@
 
 #define DEVICE_MTD_NAME 		"/dev/mtd"
 #define DEVICE_UBI_NAME 		"/dev/ubi"
+#define DEVICE_UBI_CTRL 		"/dev/ubi_ctrl"
+#define SYS_UBI				"/sys/class/ubi"
+#define SYS_UBI_MTD_NUM			"/sys/class/ubi/ubi%d/mtd_num"
 #define SYS_UBI_VOLUME_COUNT		"/sys/class/ubi/ubi%d/volumes_count"
 #define SYS_UBI_VOLUME_NAME		"/sys/class/ubi/ubi%d/ubi%d_%d/name"
 
@@ -196,7 +199,11 @@ static enum device_type get_device_type(char *device)
 	enum device_type type = DEVICE_NONE;
 
 	if (!strncmp(device, DEVICE_MTD_NAME, strlen(DEVICE_MTD_NAME)))
+		if (strchr(device, DEVNAME_SEPARATOR)) {
+			type = DEVICE_UBI;
+		} else {
 			type = DEVICE_MTD;
+		}
 	else if (!strncmp(device, DEVICE_UBI_NAME, strlen(DEVICE_UBI_NAME)))
 		type = DEVICE_UBI;
 	else if (strlen(device) > 0)
@@ -217,6 +224,77 @@ static int ubi_get_dev_id(char *device)
 	return dev_id;
 }
 
+static int mtd_get_dev_id(char *device)
+{
+	int dev_id = -1;
+	char *sep;
+
+	sep = strrchr(device, 'd');
+	if (sep)
+		sscanf(sep + 1, "%d", &dev_id);
+
+	return dev_id;
+}
+
+static int ubi_get_dev_id_from_mtd(char *device)
+{
+	DIR *sysfs_ubi;
+	struct dirent *dirent;
+	int mtd_id;
+
+	mtd_id = mtd_get_dev_id(device);
+	if (mtd_id < 0)
+		return -1;
+
+	sysfs_ubi = opendir(SYS_UBI);
+	if (!sysfs_ubi)
+		return -1;
+
+	while (1) {
+		int ubi_num, ret;
+
+		dirent = readdir(sysfs_ubi);
+		if (!dirent)
+			break;
+
+		if (strlen(dirent->d_name) >= 255) {
+			closedir(sysfs_ubi);
+			return -1;
+		}
+
+		ret = sscanf(dirent->d_name, "ubi%d", &ubi_num);
+		if (ret == 1) {
+			char filename[DEVNAME_MAX_LENGTH];
+			char data[DEVNAME_MAX_LENGTH];
+			int fd, n, num_mtd = -1;
+
+			snprintf(filename, sizeof(filename), SYS_UBI_MTD_NUM, ubi_num);
+			fd = open(filename, O_RDONLY);
+			if (fd < 0)
+				continue;
+
+			n = read(fd, data, sizeof(data));
+			close(fd);
+			if (n < 0)
+				continue;
+
+			if (sscanf(data, "%d", &num_mtd) != 1)
+				num_mtd = -1;
+
+			if (num_mtd < 0)
+				continue;
+
+			if (num_mtd == mtd_id) {
+				closedir(sysfs_ubi);
+				return ubi_num;
+			}
+		}
+	}
+
+	closedir(sysfs_ubi);
+	return -1;
+}
+
 static int ubi_get_num_volume(char *device)
 {
 	char filename[DEVNAME_MAX_LENGTH];
@@ -308,9 +386,48 @@ static int ubi_update_name(struct uboot_flash_env *dev)
 {
 	char device[DEVNAME_MAX_LENGTH];
 	char volume[DEVNAME_MAX_LENGTH];
-	int dev_id, vol_id, ret = -EBADF;
+	int dev_id, vol_id, fd, ret = -EBADF;
+	struct stat st;
 	char *sep;
 
+	if (!strncmp(dev->devname, DEVICE_MTD_NAME, strlen(DEVICE_MTD_NAME)))
+	{
+		sep = strchr(dev->devname, DEVNAME_SEPARATOR);
+		if (sep)
+		{
+			memset(device, 0, DEVNAME_MAX_LENGTH);
+			memcpy(device, dev->devname, sep - dev->devname);
+
+			memset(volume, 0, DEVNAME_MAX_LENGTH);
+			sscanf(sep + 1, "%s", &volume[0]);
+
+			ret = ubi_get_dev_id_from_mtd(device);
+			if (ret < 0) {
+				struct ubi_attach_req req;
+
+				memset(&req, 0, sizeof(struct ubi_attach_req));
+				req.ubi_num = UBI_DEV_NUM_AUTO;
+				req.mtd_num = mtd_get_dev_id(device);
+				req.vid_hdr_offset = 0;
+
+				fd = open(DEVICE_UBI_CTRL, O_RDONLY);
+				if (fd == -1)
+					return -EBADF;
+
+				ret = ioctl(fd, UBI_IOCATT, &req);
+				close(fd);
+				if (ret == -1)
+					return -EBADF;
+
+				sprintf(dev->devname, DEVICE_UBI_NAME"%d:%s", req.ubi_num, volume);
+			} else {
+				sprintf(dev->devname, DEVICE_UBI_NAME"%d:%s", ret, volume);
+			}
+		} else {
+			return -EBADF;
+		}
+	}
+
 	sep = strchr(dev->devname, DEVNAME_SEPARATOR);
 	if (sep)
 	{