mtd: spi-nor: Fix divide by zero for spi-nor-generic flashes

We failed to initialize n_banks for spi-nor-generic flashes, which
caused a devide by zero when computing the bank_size.

By default we consider that all chips have a single bank. Initialize
the default number of banks for spi-nor-generic flashes. Even if the
bug is fixed with this simple initialization, check the n_banks value
before dividing so that we make sure this kind of bug won't occur again
if some other struct instance is created uninitialized.

Suggested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217448
Fixes: 9d6c5d64f028 ("mtd: spi-nor: Introduce the concept of bank")
Link: https://lore.kernel.org/all/20230516225108.29194-1-todd.e.brandt@intel.com/
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230518085440.2363676-1-tudor.ambarus@linaro.org

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 0bb0ad14a2fc01c97d8e20144f8844186aea17df..5f29fac8669a301e8010566eee02edfdcdb66620 100644 (file)
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2018,6 +2018,7 @@ static const struct spi_nor_manufacturer *manufacturers[] = {
 
 static const struct flash_info spi_nor_generic_flash = {
        .name = "spi-nor-generic",
+       .n_banks = 1,
        /*
         * JESD216 rev A doesn't specify the page size, therefore we need a
         * sane default.
@@ -2921,7 +2922,8 @@ static void spi_nor_late_init_params(struct spi_nor *nor)
        if (nor->flags & SNOR_F_HAS_LOCK && !nor->params->locking_ops)
                spi_nor_init_default_locking_ops(nor);
 
-       nor->params->bank_size = div64_u64(nor->params->size, nor->info->n_banks);
+       if (nor->info->n_banks > 1)
+               params->bank_size = div64_u64(params->size, nor->info->n_banks);
 }
 
 /**
@@ -2987,6 +2989,7 @@ static void spi_nor_init_default_params(struct spi_nor *nor)
        /* Set SPI NOR sizes. */
        params->writesize = 1;
        params->size = (u64)info->sector_size * info->n_sectors;
+       params->bank_size = params->size;
        params->page_size = info->page_size;
 
        if (!(info->flags & SPI_NOR_NO_FR)) {