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 @@ -242,13 +244,61 @@ static int part_erase(struct mtd_info *m
23 struct mtd_part *part = mtd_to_part(mtd);
27 + instr->partial_start = false;
28 + if (mtd->flags & MTD_ERASE_PARTIAL) {
32 + instr->erase_buf = kmalloc(part->parent->erasesize, GFP_ATOMIC);
33 + if (!instr->erase_buf)
36 + mtd_ofs = part->offset + instr->addr;
37 + instr->erase_buf_ofs = do_div(mtd_ofs, part->parent->erasesize);
39 + if (instr->erase_buf_ofs > 0) {
40 + instr->addr -= instr->erase_buf_ofs;
41 + ret = mtd_read(part->parent,
42 + instr->addr + part->offset,
43 + part->parent->erasesize,
44 + &readlen, instr->erase_buf);
46 + instr->len += instr->erase_buf_ofs;
47 + instr->partial_start = true;
49 + mtd_ofs = part->offset + part->mtd.size;
50 + instr->erase_buf_ofs = part->parent->erasesize -
51 + do_div(mtd_ofs, part->parent->erasesize);
53 + if (instr->erase_buf_ofs > 0) {
54 + instr->len += instr->erase_buf_ofs;
55 + ret = mtd_read(part->parent,
56 + part->offset + instr->addr +
57 + instr->len - part->parent->erasesize,
58 + part->parent->erasesize, &readlen,
65 + kfree(instr->erase_buf);
71 instr->addr += part->offset;
72 ret = part->parent->_erase(part->parent, instr);
74 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
75 instr->fail_addr -= part->offset;
76 instr->addr -= part->offset;
77 + if (mtd->flags & MTD_ERASE_PARTIAL)
78 + kfree(instr->erase_buf);
84 @@ -256,6 +306,25 @@ void mtd_erase_callback(struct erase_inf
86 if (instr->mtd->_erase == part_erase) {
87 struct mtd_part *part = mtd_to_part(instr->mtd);
90 + if (instr->mtd->flags & MTD_ERASE_PARTIAL) {
91 + if (instr->partial_start) {
92 + part->parent->_write(part->parent,
93 + instr->addr, instr->erase_buf_ofs,
94 + &wrlen, instr->erase_buf);
95 + instr->addr += instr->erase_buf_ofs;
97 + instr->len -= instr->erase_buf_ofs;
98 + part->parent->_write(part->parent,
99 + instr->addr + instr->len,
100 + instr->erase_buf_ofs, &wrlen,
102 + part->parent->erasesize -
103 + instr->erase_buf_ofs);
105 + kfree(instr->erase_buf);
108 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
109 instr->fail_addr -= part->offset;
110 @@ -599,19 +668,22 @@ static struct mtd_part *allocate_partiti
111 remainder = do_div(tmp, wr_alignment);
112 if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
113 /* Doesn't start on a boundary of major erase size */
114 - /* FIXME: Let it be writable if it is on a boundary of
115 - * _minor_ erase size though */
116 - slave->mtd.flags &= ~MTD_WRITEABLE;
117 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
119 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
120 + if (((u32)slave->mtd.size) > parent->erasesize)
121 + slave->mtd.flags &= ~MTD_WRITEABLE;
123 + slave->mtd.erasesize = slave->mtd.size;
126 - tmp = slave->mtd.size;
127 + tmp = slave->offset + slave->mtd.size;
128 remainder = do_div(tmp, wr_alignment);
129 if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
130 - slave->mtd.flags &= ~MTD_WRITEABLE;
131 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
133 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
135 + if ((u32)slave->mtd.size > parent->erasesize)
136 + slave->mtd.flags &= ~MTD_WRITEABLE;
138 + slave->mtd.erasesize = slave->mtd.size;
141 mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);
142 --- a/include/linux/mtd/mtd.h
143 +++ b/include/linux/mtd/mtd.h
144 @@ -56,6 +56,10 @@ struct erase_info {
147 struct erase_info *next;
151 + bool partial_start;
154 struct mtd_erase_region_info {