mtd: gpio_flash: handle case where offset + len exceeds the window size
Fix the bug in handling gpio flash read/write when offset + len from MTD exceeds the window size Signed-off-by: Aaron Wu <Aaron.wu@analog.com> [Brian: made some commentary edits. Also note that the BUG_ON() was provably false for all non-negative inputs (since x % y <= x), so we dropped it.] Signed-off-by: Brian Norris <computersforpeace@gmail.com>
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@ -99,22 +99,28 @@ static map_word gf_read(struct map_info *map, unsigned long ofs)
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* @from: flash offset to copy from
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* @len: how much to copy
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*
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* We rely on the MTD layer to chunk up copies such that a single request here
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* will not cross a window size. This allows us to only wiggle the GPIOs once
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* before falling back to a normal memcpy. Reading the higher layer code shows
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* that this is indeed the case, but add a BUG_ON() to future proof.
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* The "from" region may straddle more than one window, so toggle the GPIOs for
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* each window region before reading its data.
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*/
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static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
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{
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struct async_state *state = gf_map_info_to_state(map);
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gf_set_gpios(state, from);
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int this_len;
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/* BUG if operation crosses the win_size */
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BUG_ON(!((from + len) % state->win_size <= (from + len)));
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while (len) {
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if ((from % state->win_size) + len > state->win_size)
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this_len = state->win_size - (from % state->win_size);
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else
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this_len = len;
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/* operation does not cross the win_size, so one shot it */
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memcpy_fromio(to, map->virt + (from % state->win_size), len);
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gf_set_gpios(state, from);
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memcpy_fromio(to, map->virt + (from % state->win_size),
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this_len);
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len -= this_len;
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from += this_len;
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to += this_len;
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}
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}
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/**
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@ -147,13 +153,21 @@ static void gf_copy_to(struct map_info *map, unsigned long to,
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{
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struct async_state *state = gf_map_info_to_state(map);
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gf_set_gpios(state, to);
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int this_len;
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/* BUG if operation crosses the win_size */
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BUG_ON(!((to + len) % state->win_size <= (to + len)));
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while (len) {
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if ((to % state->win_size) + len > state->win_size)
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this_len = state->win_size - (to % state->win_size);
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else
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this_len = len;
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/* operation does not cross the win_size, so one shot it */
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memcpy_toio(map->virt + (to % state->win_size), from, len);
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gf_set_gpios(state, to);
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memcpy_toio(map->virt + (to % state->win_size), from, len);
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len -= this_len;
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to += this_len;
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from += this_len;
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}
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}
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static const char * const part_probe_types[] = {
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