libmtd: add OOB read and write interfaces

This patch is based on Kevin Cernekee's patch posted to the MTD mailing
list. It adds 'mtd_read_oob()' and 'mtd_write_oob()' interfaces support.

The interfaces use MEMREADOOB64/MEMWRITEOOB64 MTD ioctls if possible, and
fall-back to MEMREADOOB/MEMWRITEOOB if the 64-bit versions are not supported.
The information about ioctls support is then cashed in 'offs64_ioctls'
libmtd flag.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

2 files changed, 130 insertions, 1 deletions

diff --git a/include/libmtd.h b/include/libmtd.h
index 2bf9859..afaba42 100644
--- a/include/libmtd.h
+++ b/include/libmtd.h
@@ -216,6 +216,40 @@ int mtd_write(const struct mtd_dev_info *mtd, int fd, int eb, int offs,
 	      void *buf, int len);
 
 /**
+ * mtd_read_oob - read out-of-band area.
+ * @desc: MTD library descriptor
+ * @mtd: MTD device description object
+ * @fd: MTD device node file descriptor
+ * @start: page-aligned start address
+ * @length: number of OOB bytes to read
+ * @data: read buffer
+ *
+ * This function reads @length OOB bytes starting from address @start on
+ * MTD device described by @fd. The address is specified as page byte offset
+ * from the beginning of the MTD device. This function returns %0 in case of
+ * success and %-1 in case of failure.
+ */
+int mtd_read_oob(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
+		 uint64_t start, uint64_t length, void *data);
+
+/**
+ * mtd_write_oob - write out-of-band area.
+ * @desc: MTD library descriptor
+ * @mtd: MTD device description object
+ * @fd: MTD device node file descriptor
+ * @start: page-aligned start address
+ * @length: number of OOB bytes to write
+ * @data: write buffer
+ *
+ * This function writes @length OOB bytes starting from address @start on
+ * MTD device described by @fd. The address is specified as page byte offset
+ * from the beginning of the MTD device. Returns %0 in case of success and %-1
+ * in case of failure.
+ */
+int mtd_write_oob(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
+		  uint64_t start, uint64_t length, void *data);
+
+/**
  * mtd_write_img - write a file to MTD device.
  * @mtd: MTD device description object
  * @fd: MTD device node file descriptor
@@ -236,7 +270,7 @@ int mtd_write_img(const struct mtd_dev_info *mtd, int fd, int eb, int offs,
  * @node: the node to test
  *
  * This function tests whether @node is an MTD device node and returns %1 if it
- * is, and %-1 if it is not (errno is ENODEV in this case) or if an error
+ * is, and %-1 if it is not (errno is %ENODEV in this case) or if an error
  * occurred.
  */
 int mtd_probe_node(libmtd_t desc, const char *node);
diff --git a/lib/libmtd.c b/lib/libmtd.c
index a976679..0010790 100644
--- a/lib/libmtd.c
+++ b/lib/libmtd.c
@@ -1054,6 +1054,101 @@ int mtd_write(const struct mtd_dev_info *mtd, int fd, int eb, int offs,
 	return 0;
 }
 
+int do_oob_op(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
+	      uint64_t start, uint64_t length, void *data, unsigned int cmd64,
+	      unsigned int cmd)
+{
+	int ret;
+	struct mtd_oob_buf64 oob64;
+	struct mtd_oob_buf oob;
+	unsigned long long max_offs;
+	const char *cmd64_str, *cmd_str;
+	struct libmtd *lib = (struct libmtd *)desc;
+
+	if (cmd64 ==  MEMREADOOB64) {
+		cmd64_str = "MEMREADOOB64";
+		cmd_str   = "MEMREADOOB";
+	} else {
+		cmd64_str = "MEMWRITEOOB64";
+		cmd_str   = "MEMWRITEOOB";
+	}
+
+	max_offs = (unsigned long long)mtd->eb_cnt * mtd->eb_size;
+	if (start >= max_offs) {
+		errmsg("bad page address %llu, mtd%d has %d eraseblocks "
+		       "(%llu bytes)", (unsigned long long) start, mtd->mtd_num,
+		       mtd->eb_cnt, max_offs);
+		errno = EINVAL;
+		return -1;
+	}
+	if (start % mtd->min_io_size) {
+		errmsg("unaligned address %llu, mtd%d page size is %d",
+		       (unsigned long long)start, mtd->mtd_num,
+		       mtd->min_io_size);
+		errno = EINVAL;
+		return -1;
+	}
+
+	oob64.start = start;
+	oob64.length = length;
+	oob64.usr_ptr = (uint64_t)(unsigned long)data;
+
+	if (lib->offs64_ioctls == OFFS64_IOCTLS_SUPPORTED ||
+	    lib->offs64_ioctls == OFFS64_IOCTLS_UNKNOWN) {
+		ret = ioctl(fd, cmd64, &oob64);
+		if (ret == 0)
+			return ret;
+
+		if (errno != ENOTTY ||
+		    lib->offs64_ioctls != OFFS64_IOCTLS_UNKNOWN) {
+			sys_errmsg("%s ioctl failed for mtd%d, offset %llu "
+				   "(eraseblock %llu)", cmd64_str, mtd->mtd_num,
+				   (unsigned long long)start,
+				   (unsigned long long)start / mtd->eb_size);
+		}
+
+		/*
+		 * MEMREADOOB64/MEMWRITEOOB64 support was added in kernel
+		 * version 2.6.31, so probably we are working with older kernel
+		 * and these ioctls are not supported.
+		 */
+		lib->offs64_ioctls = OFFS64_IOCTLS_NOT_SUPPORTED;
+	}
+
+	if (oob64.start > 0xFFFFFFFFULL) {
+		errmsg("this system can address only up to address %lu",
+		       0xFFFFFFFFUL);
+		errno = EINVAL;
+		return -1;
+	}
+
+	oob.start = oob64.start;
+	oob.length = oob64.length;
+	oob.ptr = data;
+
+	ret = ioctl(fd, cmd, &oob);
+	if (ret < 0)
+		sys_errmsg("%s ioctl failed for mtd%d, offset %llu "
+			   "(eraseblock %llu)", cmd_str, mtd->mtd_num,
+			   (unsigned long long)start,
+			   (unsigned long long)start / mtd->eb_size);
+	return ret;
+}
+
+int mtd_read_oob(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
+		 uint64_t start, uint64_t length, void *data)
+{
+	return do_oob_op(desc, mtd, fd, start, length, data,
+			 MEMREADOOB64, MEMREADOOB);
+}
+
+int mtd_write_oob(libmtd_t desc, const struct mtd_dev_info *mtd, int fd,
+		  uint64_t start, uint64_t length, void *data)
+{
+	return do_oob_op(desc, mtd, fd, start, length, data,
+			 MEMWRITEOOB64, MEMWRITEOOB);
+}
+
 int mtd_write_img(const struct mtd_dev_info *mtd, int fd, int eb, int offs,
 		  const char *img_name)
 {