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mtd: map_rom: Support UBI on ROM
UBI needs to know the physical erase block size, even on read-only devices, since it defines the on-device layout. Use a device-tree provided value to support previously written UBI on read-only NOR. UBI also needs a non-zero writebufsize, so we set it to one. Note: This was implemented because hardware write-protected CFI NOR cannot be probed for the physical erase block size. Signed-off-by: Joe Schultz <jschultz@xes-inc.ccom> Signed-off-by: Aaron Sierra <asierra@xes-inc.ccom> [Brian: removed unneeded #ifdef, note 'optional' erase-size property] Signed-off-by: Brian Norris <computersforpeace@gmail.com>
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2 changed files with 17 additions and 1 deletions
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@ -36,6 +36,11 @@ are defined:
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- vendor-id : Contains the flash chip's vendor id (1 byte).
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- device-id : Contains the flash chip's device id (1 byte).
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For ROM compatible devices (and ROM fallback from cfi-flash), the following
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additional (optional) property is defined:
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- erase-size : The chip's physical erase block size in bytes.
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The device tree may optionally contain sub-nodes describing partitions of the
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address space. See partition.txt for more detail.
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@ -11,6 +11,7 @@
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/of.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/map.h>
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@ -28,6 +29,15 @@ static struct mtd_chip_driver maprom_chipdrv = {
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.module = THIS_MODULE
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};
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static unsigned int default_erasesize(struct map_info *map)
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{
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const __be32 *erase_size = NULL;
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erase_size = of_get_property(map->device_node, "erase-size", NULL);
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return !erase_size ? map->size : be32_to_cpu(*erase_size);
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}
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static struct mtd_info *map_rom_probe(struct map_info *map)
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{
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struct mtd_info *mtd;
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@ -47,8 +57,9 @@ static struct mtd_info *map_rom_probe(struct map_info *map)
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mtd->_sync = maprom_nop;
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mtd->_erase = maprom_erase;
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mtd->flags = MTD_CAP_ROM;
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mtd->erasesize = map->size;
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mtd->erasesize = default_erasesize(map);
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mtd->writesize = 1;
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mtd->writebufsize = 1;
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__module_get(THIS_MODULE);
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return mtd;
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