OpenWrt – Rev 1

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--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -36,6 +36,8 @@
 #include "mtdcore.h"
 #include "mtdsplit/mtdsplit.h"
 
+#define MTD_ERASE_PARTIAL      0x8000 /* partition only covers parts of an erase block */
+
 /* Our partition linked list */
 static LIST_HEAD(mtd_partitions);
 static DEFINE_MUTEX(mtd_partitions_mutex);
@@ -234,13 +236,61 @@ static int part_erase(struct mtd_info *m
        struct mtd_part *part = PART(mtd);
        int ret;
 
+
+       instr->partial_start = false;
+       if (mtd->flags & MTD_ERASE_PARTIAL) {
+               size_t readlen = 0;
+               u64 mtd_ofs;
+
+               instr->erase_buf = kmalloc(part->master->erasesize, GFP_ATOMIC);
+               if (!instr->erase_buf)
+                       return -ENOMEM;
+
+               mtd_ofs = part->offset + instr->addr;
+               instr->erase_buf_ofs = do_div(mtd_ofs, part->master->erasesize);
+
+               if (instr->erase_buf_ofs > 0) {
+                       instr->addr -= instr->erase_buf_ofs;
+                       ret = mtd_read(part->master,
+                               instr->addr + part->offset,
+                               part->master->erasesize,
+                               &readlen, instr->erase_buf);
+
+                       instr->len += instr->erase_buf_ofs;
+                       instr->partial_start = true;
+               } else {
+                       mtd_ofs = part->offset + part->mtd.size;
+                       instr->erase_buf_ofs = part->master->erasesize -
+                               do_div(mtd_ofs, part->master->erasesize);
+
+                       if (instr->erase_buf_ofs > 0) {
+                               instr->len += instr->erase_buf_ofs;
+                               ret = mtd_read(part->master,
+                                       part->offset + instr->addr +
+                                       instr->len - part->master->erasesize,
+                                       part->master->erasesize, &readlen,
+                                       instr->erase_buf);
+                       } else {
+                               ret = 0;
+                       }
+               }
+               if (ret < 0) {
+                       kfree(instr->erase_buf);
+                       return ret;
+               }
+
+       }
+
        instr->addr += part->offset;
        ret = part->master->_erase(part->master, instr);
        if (ret) {
                if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
                        instr->fail_addr -= part->offset;
                instr->addr -= part->offset;
+               if (mtd->flags & MTD_ERASE_PARTIAL)
+                       kfree(instr->erase_buf);
        }
+
        return ret;
 }
 
@@ -248,7 +298,25 @@ void mtd_erase_callback(struct erase_inf
 {
        if (instr->mtd->_erase == part_erase) {
                struct mtd_part *part = PART(instr->mtd);
+               size_t wrlen = 0;
 
+               if (instr->mtd->flags & MTD_ERASE_PARTIAL) {
+                       if (instr->partial_start) {
+                               part->master->_write(part->master,
+                                       instr->addr, instr->erase_buf_ofs,
+                                       &wrlen, instr->erase_buf);
+                               instr->addr += instr->erase_buf_ofs;
+                       } else {
+                               instr->len -= instr->erase_buf_ofs;
+                               part->master->_write(part->master,
+                                       instr->addr + instr->len,
+                                       instr->erase_buf_ofs, &wrlen,
+                                       instr->erase_buf +
+                                       part->master->erasesize -
+                                       instr->erase_buf_ofs);
+                       }
+                       kfree(instr->erase_buf);
+               }
                if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
                        instr->fail_addr -= part->offset;
                instr->addr -= part->offset;
@@ -515,17 +583,20 @@ static struct mtd_part *allocate_partiti
        if ((slave->mtd.flags & MTD_WRITEABLE) &&
            mtd_mod_by_eb(slave->offset, &slave->mtd)) {
                /* Doesn't start on a boundary of major erase size */
-               /* FIXME: Let it be writable if it is on a boundary of
-                * _minor_ erase size though */
-               slave->mtd.flags &= ~MTD_WRITEABLE;
-               printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
-                       part->name);
+               slave->mtd.flags |= MTD_ERASE_PARTIAL;
+               if (((u32) slave->mtd.size) > master->erasesize)
+                       slave->mtd.flags &= ~MTD_WRITEABLE;
+               else
+                       slave->mtd.erasesize = slave->mtd.size;
        }
        if ((slave->mtd.flags & MTD_WRITEABLE) &&
-           mtd_mod_by_eb(slave->mtd.size, &slave->mtd)) {
-               slave->mtd.flags &= ~MTD_WRITEABLE;
-               printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
-                       part->name);
+           mtd_mod_by_eb(slave->offset + slave->mtd.size, &slave->mtd)) {
+               slave->mtd.flags |= MTD_ERASE_PARTIAL;
+
+               if ((u32) slave->mtd.size > master->erasesize)
+                       slave->mtd.flags &= ~MTD_WRITEABLE;
+               else
+                       slave->mtd.erasesize = slave->mtd.size;
        }
 
        slave->mtd.ecclayout = master->ecclayout;
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -55,6 +55,10 @@ struct erase_info {
        u_long priv;
        u_char state;
        struct erase_info *next;
+
+       u8 *erase_buf;
+       u32 erase_buf_ofs;
+       bool partial_start;
 };
 
 struct mtd_erase_region_info {