[PATCH 7/8] cdev: Add function to get unallocated start of device

[Sascha Hauer <s.hauer@pengutronix.de>]

On several SoCs barebox is written to the raw device in front of the
first partition. So far we blindly trust that there is enough space
available for the barebox image. Start changing this by adding a
function that retrieves the available space.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/partitions.c | 28 ++++++++++++++++++++++++++++
 include/driver.h    |  1 +
 2 files changed, 29 insertions(+)

diff --git a/common/partitions.c b/common/partitions.c
index d80878e065..e36341fc1e 100644
--- a/common/partitions.c
+++ b/common/partitions.c
@@ -156,3 +156,31 @@ int partition_parser_register(struct partition_parser *p)
 
 	return 0;
 }
+
+/**
+ * cdev_unallocated_start - return unallocated space
+ * @name: The cdev name
+ *
+ * This function returns the space that is not allocated by any partition
+ * at the start of a device.
+ *
+ * Return: The unallocated space at the start of the device in bytes
+ */
+loff_t cdev_unallocated_start(const char *name)
+{
+	struct cdev *cdev, *partcdev;
+	loff_t start;
+
+	cdev = cdev_by_name(name);
+	if (!cdev)
+		return 0;
+
+	start = cdev->size;
+
+	list_for_each_entry(partcdev, &cdev->partitions, partition_entry) {
+		if (partcdev->offset < start)
+			start = partcdev->offset;
+	}
+
+	return start;
+}
diff --git a/include/driver.h b/include/driver.h
index c7f5903fce..38aa3cf8f5 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -494,6 +494,7 @@ ssize_t cdev_read(struct cdev *cdev, void *buf, size_t count, loff_t offset, ulo
 ssize_t cdev_write(struct cdev *cdev, const void *buf, size_t count, loff_t offset, ulong flags);
 int cdev_ioctl(struct cdev *cdev, int cmd, void *buf);
 int cdev_erase(struct cdev *cdev, loff_t count, loff_t offset);
+loff_t cdev_unallocated_start(const char *name);
 
 #define DEVFS_PARTITION_FIXED		(1U << 0)
 #define DEVFS_PARTITION_READONLY	(1U << 1)
-- 
2.30.2


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