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>

diff --git a/drivers/mtd/tests/mtd_nandecctest.c b/drivers/mtd/tests/mtd_nandecctest.c
index ff97b10..caaeb64 100644 (file)
--- 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,