[PATCH v2] mtd: spi-nor: fix selection of uniform erase type in flexible conf

[Tudor.Ambarus]

There are uniform, non-uniform and flexible erase flash configurations.

The non-uniform erase types, are the erase types that can _not_ erase
the entire flash by their own.

As the code was, in case flashes had flexible erase capabilities
(support both uniform and non-uniform erase types in the same flash
configuration) and supported multiple uniform erase type sizes, the
code did not sort the uniform erase types, and could select a wrong
erase type size.

Sort the uniform erase mask in case of flexible erase flash
configurations, in order to select the best uniform erase type size.

Uniform, non-uniform, and flexible configurations with just a valid
uniform erase type, are not affected by this change.

Uniform erase tested on mx25l3273fm2i-08g and sst26vf064B-104i/sn.
Non uniform erase tested on sst26vf064B-104i/sn.

Fixes: 5390a8df769e ("mtd: spi-nor: add support to non-uniform SFDP SPI NOR 
flash memories")
Signed-off-by: Tudor Ambarus <tudor.amba...@microchip.com>
---
v2: drop uneeded change

 drivers/mtd/spi-nor/spi-nor.c | 47 +++++++++++++++++++++++++++++++++----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 69784b3b8ca1..4c7e4dc25006 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2529,6 +2529,34 @@ static int spi_nor_map_cmp_erase_type(const void *l, 
const void *r)
 }
 
 /**
+ * spi_nor_sort_erase_mask() - sort erase mask
+ * @map:       the erase map of the SPI NOR
+ * @erase_mask:        the erase type mask to be sorted
+ *
+ * Replicate the sort done for the map's erase types in BFPT: sort the erase
+ * mask in ascending order with the smallest erase type size starting from
+ * BIT(0) in the sorted erase mask.
+ *
+ * Return: sorted erase mask.
+ */
+static u8 spi_nor_sort_erase_mask(struct spi_nor_erase_map *map, u8 erase_mask)
+{
+       struct spi_nor_erase_type *erase_type = map->erase_type;
+       int i;
+       u8 sorted_erase_mask = 0;
+
+       if (!erase_mask)
+               return 0;
+
+       /* Replicate the sort done for the map's erase types. */
+       for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++)
+               if (erase_type[i].size && erase_mask & BIT(erase_type[i].idx))
+                       sorted_erase_mask |= BIT(i);
+
+       return sorted_erase_mask;
+}
+
+/**
  * spi_nor_regions_sort_erase_types() - sort erase types in each region
  * @map:       the erase map of the SPI NOR
  *
@@ -2543,19 +2571,13 @@ static int spi_nor_map_cmp_erase_type(const void *l, 
const void *r)
 static void spi_nor_regions_sort_erase_types(struct spi_nor_erase_map *map)
 {
        struct spi_nor_erase_region *region = map->regions;
-       struct spi_nor_erase_type *erase_type = map->erase_type;
-       int i;
        u8 region_erase_mask, sorted_erase_mask;
 
        while (region) {
                region_erase_mask = region->offset & SNOR_ERASE_TYPE_MASK;
 
-               /* Replicate the sort done for the map's erase types. */
-               sorted_erase_mask = 0;
-               for (i = 0; i < SNOR_ERASE_TYPE_MAX; i++)
-                       if (erase_type[i].size &&
-                           region_erase_mask & BIT(erase_type[i].idx))
-                               sorted_erase_mask |= BIT(i);
+               sorted_erase_mask = spi_nor_sort_erase_mask(map,
+                                                           region_erase_mask);
 
                /* Overwrite erase mask. */
                region->offset = (region->offset & ~SNOR_ERASE_TYPE_MASK) |
@@ -2985,7 +3007,7 @@ static int spi_nor_init_non_uniform_erase_map(struct 
spi_nor *nor,
        u64 offset;
        u32 region_count;
        int i, j;
-       u8 erase_type;
+       u8 erase_type, uniform_erase_type;
 
        region_count = SMPT_MAP_REGION_COUNT(*smpt);
        /*
@@ -2998,7 +3020,7 @@ static int spi_nor_init_non_uniform_erase_map(struct 
spi_nor *nor,
                return -ENOMEM;
        map->regions = region;
 
-       map->uniform_erase_type = 0xff;
+       uniform_erase_type = 0xff;
        offset = 0;
        /* Populate regions. */
        for (i = 0; i < region_count; i++) {
@@ -3013,12 +3035,15 @@ static int spi_nor_init_non_uniform_erase_map(struct 
spi_nor *nor,
                 * Save the erase types that are supported in all regions and
                 * can erase the entire flash memory.
                 */
-               map->uniform_erase_type &= erase_type;
+               uniform_erase_type &= erase_type;
 
                offset = (region[i].offset & ~SNOR_ERASE_FLAGS_MASK) +
                         region[i].size;
        }
 
+       map->uniform_erase_type = spi_nor_sort_erase_mask(map,
+                                                         uniform_erase_type);
+
        spi_nor_region_mark_end(&region[i - 1]);
 
        return 0;
-- 
2.9.4