1 From: Felix Fietkau <nbd@nbd.name>
2 Subject: mtd: implement write support for partitions covering only a part of an eraseblock (buffer data that would otherwise be erased)
4 lede-commit: 87a8e8ac1067f58ba831c4aae443f3655c31cd80
5 Signed-off-by: Felix Fietkau <nbd@nbd.name>
7 drivers/mtd/mtdpart.c | 90 ++++++++++++++++++++++++++++++++++++++++++++-----
8 include/linux/mtd/mtd.h | 4 +++
9 2 files changed, 85 insertions(+), 9 deletions(-)
11 --- a/drivers/mtd/mtdpart.c
12 +++ b/drivers/mtd/mtdpart.c
15 #include "mtdsplit/mtdsplit.h"
17 +#define MTD_ERASE_PARTIAL 0x8000 /* partition only covers parts of an erase block */
19 /* Our partition linked list */
20 static LIST_HEAD(mtd_partitions);
21 static DEFINE_MUTEX(mtd_partitions_mutex);
22 @@ -206,11 +208,77 @@ static int part_erase(struct mtd_info *m
24 struct mtd_part *part = mtd_to_part(mtd);
27 + u8 *erase_buf = NULL;
28 + u32 erase_buf_ofs = 0;
29 + bool partial_start = false;
31 + if (mtd->flags & MTD_ERASE_PARTIAL) {
35 + erase_buf = kmalloc(part->parent->erasesize, GFP_ATOMIC);
39 + mtd_ofs = part->offset + instr->addr;
40 + erase_buf_ofs = do_div(mtd_ofs, part->parent->erasesize);
42 + if (erase_buf_ofs > 0) {
43 + instr->addr -= erase_buf_ofs;
44 + ret = mtd_read(part->parent,
45 + instr->addr + part->offset,
46 + part->parent->erasesize,
47 + &readlen, erase_buf);
49 + instr->len += erase_buf_ofs;
50 + partial_start = true;
52 + mtd_ofs = part->offset + part->mtd.size;
53 + erase_buf_ofs = part->parent->erasesize -
54 + do_div(mtd_ofs, part->parent->erasesize);
56 + if (erase_buf_ofs > 0) {
57 + instr->len += erase_buf_ofs;
58 + ret = mtd_read(part->parent,
59 + part->offset + instr->addr +
60 + instr->len - part->parent->erasesize,
61 + part->parent->erasesize, &readlen,
74 instr->addr += part->offset;
75 ret = part->parent->_erase(part->parent, instr);
76 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
77 instr->fail_addr -= part->offset;
79 + if (mtd->flags & MTD_ERASE_PARTIAL) {
80 + if (partial_start) {
81 + part->parent->_write(part->parent,
82 + instr->addr, erase_buf_ofs,
84 + instr->addr += erase_buf_ofs;
86 + instr->len -= erase_buf_ofs;
87 + part->parent->_write(part->parent,
88 + instr->addr + instr->len,
89 + erase_buf_ofs, &wrlen,
91 + part->parent->erasesize -
97 instr->addr -= part->offset;
100 @@ -525,19 +593,22 @@ static struct mtd_part *allocate_partiti
101 remainder = do_div(tmp, wr_alignment);
102 if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
103 /* Doesn't start on a boundary of major erase size */
104 - /* FIXME: Let it be writable if it is on a boundary of
105 - * _minor_ erase size though */
106 - slave->mtd.flags &= ~MTD_WRITEABLE;
107 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
109 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
110 + if (((u32)slave->mtd.size) > parent->erasesize)
111 + slave->mtd.flags &= ~MTD_WRITEABLE;
113 + slave->mtd.erasesize = slave->mtd.size;
116 tmp = part_absolute_offset(parent) + slave->offset + slave->mtd.size;
117 remainder = do_div(tmp, wr_alignment);
118 if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
119 - slave->mtd.flags &= ~MTD_WRITEABLE;
120 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
122 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
124 + if ((u32)slave->mtd.size > parent->erasesize)
125 + slave->mtd.flags &= ~MTD_WRITEABLE;
127 + slave->mtd.erasesize = slave->mtd.size;
130 mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);