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authorBrian Norris <computersforpeace@gmail.com>2010-08-24 18:12:00 -0700
committerDavid Woodhouse <David.Woodhouse@intel.com>2010-10-24 23:37:24 +0100
commitcc26c3cd3d1cf40a07f2b19ac4c53d517bee52a5 (patch)
tree664c422944f780a1cc99f872714eeb339efef7ef /drivers/mtd
parentf4a2da0cd522a3b805ff2386c14912945bf990c7 (diff)
mtd: nand: expand nand_ecc_layout, deprecate ioctl ECCGETLAYOUT
struct nand_ecclayout is too small for many new chips; OOB regions can be as large as 448 bytes and may increase more in the future. Thus, copying that struct to user-space with the ECCGETLAYOUT ioctl is not a good idea; the ioctl would have to be updated every time there's a change to the current largest size. Instead, the old nand_ecclayout is renamed to nand_ecclayout_user and a new struct nand_ecclayout is created that can accomodate larger sizes and expand without affecting the user-space. struct nand_ecclayout can still be used in board drivers without modification -- at least for now. A new function is provided to convert from the new to the old in order to allow the deprecated ioctl to continue to work with truncated data. Perhaps the ioctl, the conversion process, and the struct nand_ecclayout_user can be removed altogether in the future. Note: There are comments in nand/davinci_nand.c::nand_davinci_probe() regarding this issue; this driver (and maybe others) can be updated to account for extra space. All kernel drivers can use the expanded nand_ecclayout as a drop-in replacement and ignore its benefits. Signed-off-by: Brian Norris <computersforpeace@gmail.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/mtd')
-rw-r--r--drivers/mtd/mtdchar.c48
-rw-r--r--drivers/mtd/nand/davinci_nand.c3
2 files changed, 48 insertions, 3 deletions
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
index a825002123c8..24d35ba62b84 100644
--- a/drivers/mtd/mtdchar.c
+++ b/drivers/mtd/mtdchar.c
@@ -477,6 +477,39 @@ static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,
return ret;
}
+/*
+ * Copies (and truncates, if necessary) data from the larger struct,
+ * nand_ecclayout, to the smaller, deprecated layout struct,
+ * nand_ecclayout_user. This is necessary only to suppport the deprecated
+ * API ioctl ECCGETLAYOUT while allowing all new functionality to use
+ * nand_ecclayout flexibly (i.e. the struct may change size in new
+ * releases without requiring major rewrites).
+ */
+static int shrink_ecclayout(const struct nand_ecclayout *from,
+ struct nand_ecclayout_user *to)
+{
+ int i;
+
+ if (!from || !to)
+ return -EINVAL;
+
+ memset(to, 0, sizeof(*to));
+
+ to->eccbytes = min((int)from->eccbytes, MTD_MAX_ECCPOS_ENTRIES_OLD);
+ for (i = 0; i < to->eccbytes; i++)
+ to->eccpos[i] = from->eccpos[i];
+
+ for (i = 0; i < MTD_MAX_OOBFREE_ENTRIES; i++) {
+ if (from->oobfree[i].length == 0 &&
+ from->oobfree[i].offset == 0)
+ break;
+ to->oobavail += from->oobfree[i].length;
+ to->oobfree[i] = from->oobfree[i];
+ }
+
+ return 0;
+}
+
static int mtd_ioctl(struct file *file, u_int cmd, u_long arg)
{
struct mtd_file_info *mfi = file->private_data;
@@ -812,14 +845,23 @@ static int mtd_ioctl(struct file *file, u_int cmd, u_long arg)
}
#endif
+ /* This ioctl is being deprecated - it truncates the ecc layout */
case ECCGETLAYOUT:
{
+ struct nand_ecclayout_user *usrlay;
+
if (!mtd->ecclayout)
return -EOPNOTSUPP;
- if (copy_to_user(argp, mtd->ecclayout,
- sizeof(struct nand_ecclayout)))
- return -EFAULT;
+ usrlay = kmalloc(sizeof(*usrlay), GFP_KERNEL);
+ if (!usrlay)
+ return -ENOMEM;
+
+ shrink_ecclayout(mtd->ecclayout, usrlay);
+
+ if (copy_to_user(argp, usrlay, sizeof(*usrlay)))
+ ret = -EFAULT;
+ kfree(usrlay);
break;
}
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 2ac7367afe77..70698e86e437 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -749,6 +749,9 @@ static int __init nand_davinci_probe(struct platform_device *pdev)
* breaks userspace ioctl interface with mtd-utils. Once we
* resolve this issue, NAND_ECC_HW_OOB_FIRST mode can be used
* for the 4KiB page chips.
+ *
+ * TODO: Note that nand_ecclayout has now been expanded and can
+ * hold plenty of OOB entries.
*/
dev_warn(&pdev->dev, "no 4-bit ECC support yet "
"for 4KiB-page NAND\n");