mtd: mtd_nandecctest: add single bit error correction test

This adds the single bit error correction test case listed below:

Prepare data block without corruption and ECC data with single bit error,
and verify that the data block is preserved by __nand_correct_data().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/mtd/tests/mtd_nandecctest.c b/drivers/mtd/tests/mtd_nandecctest.c
index ff97b1070235..caaeb64acdea 100644
--- a/drivers/mtd/tests/mtd_nandecctest.c
+++ b/drivers/mtd/tests/mtd_nandecctest.c
@@ -48,6 +48,31 @@ static void single_bit_error_data(void *error_data, void *correct_data,
         __change_bit_le(offset, error_data);
 }
 
+static unsigned int random_ecc_bit(size_t size)
+{
+        unsigned int offset = random32() % (3 * BITS_PER_BYTE);
+
+        if (size == 256) {
+                /*
+                 * Don't inject a bit error into the insignificant bits (16th
+                 * and 17th bit) in ECC code for 256 byte data block
+                 */
+                while (offset == 16 || offset == 17)
+                        offset = random32() % (3 * BITS_PER_BYTE);
+        }
+
+        return offset;
+}
+
+static void single_bit_error_ecc(void *error_ecc, void *correct_ecc,
+                                size_t size)
+{
+        unsigned int offset = random_ecc_bit(size);
+
+        memcpy(error_ecc, correct_ecc, 3);
+        __change_bit_le(offset, error_ecc);
+}
+
 static void no_bit_error(void *error_data, void *error_ecc,
                 void *correct_data, void *correct_ecc, const size_t size)
 {
@@ -76,6 +101,13 @@ static void single_bit_error_in_data(void *error_data, void *error_ecc,
         memcpy(error_ecc, correct_ecc, 3);
 }
 
+static void single_bit_error_in_ecc(void *error_data, void *error_ecc,
+                void *correct_data, void *correct_ecc, const size_t size)
+{
+        memcpy(error_data, correct_data, size);
+        single_bit_error_ecc(error_ecc, correct_ecc, size);
+}
+
 static int single_bit_error_correct(void *error_data, void *error_ecc,
                                 void *correct_data, const size_t size)
 {
@@ -101,6 +133,11 @@ static const struct nand_ecc_test nand_ecc_test[] = {
                 .prepare = single_bit_error_in_data,
                 .verify = single_bit_error_correct,
         },
+        {
+                .name = "single-bit-error-in-ecc-correct",
+                .prepare = single_bit_error_in_ecc,
+                .verify = single_bit_error_correct,
+        },
 };
 
 static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data,