mtd: mtd_nandecctest: add double bit error detection tests

This adds the double bit error detection test cases listed below:

* Prepare data block with double bit error and ECC data without
corruption, and verify that the uncorrectable error is detected by
__nand_correct_data().

* Prepare data block with single bit error and ECC data with single bit
error, and verify that the uncorrectable error is detected.

* Prepare data block without corruption and ECC data with double bit
error, and verify that the uncorrectable error is detected.

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, 79 insertions, 0 deletions

diff --git a/drivers/mtd/tests/mtd_nandecctest.c b/drivers/mtd/tests/mtd_nandecctest.c
index caaeb64acdea..b437fa425077 100644
--- a/drivers/mtd/tests/mtd_nandecctest.c
+++ b/drivers/mtd/tests/mtd_nandecctest.c
@@ -48,6 +48,22 @@ static void single_bit_error_data(void *error_data, void *correct_data,
         __change_bit_le(offset, error_data);
 }
 
+static void double_bit_error_data(void *error_data, void *correct_data,
+                                size_t size)
+{
+        unsigned int offset[2];
+
+        offset[0] = random32() % (size * BITS_PER_BYTE);
+        do {
+                offset[1] = random32() % (size * BITS_PER_BYTE);
+        } while (offset[0] == offset[1]);
+
+        memcpy(error_data, correct_data, size);
+
+        __change_bit_le(offset[0], error_data);
+        __change_bit_le(offset[1], error_data);
+}
+
 static unsigned int random_ecc_bit(size_t size)
 {
         unsigned int offset = random32() % (3 * BITS_PER_BYTE);
@@ -73,6 +89,21 @@ static void single_bit_error_ecc(void *error_ecc, void *correct_ecc,
         __change_bit_le(offset, error_ecc);
 }
 
+static void double_bit_error_ecc(void *error_ecc, void *correct_ecc,
+                                size_t size)
+{
+        unsigned int offset[2];
+
+        offset[0] = random_ecc_bit(size);
+        do {
+                offset[1] = random_ecc_bit(size);
+        } while (offset[0] == offset[1]);
+
+        memcpy(error_ecc, correct_ecc, 3);
+        __change_bit_le(offset[0], error_ecc);
+        __change_bit_le(offset[1], error_ecc);
+}
+
 static void no_bit_error(void *error_data, void *error_ecc,
                 void *correct_data, void *correct_ecc, const size_t size)
 {
@@ -122,6 +153,39 @@ static int single_bit_error_correct(void *error_data, void *error_ecc,
         return -EINVAL;
 }
 
+static void double_bit_error_in_data(void *error_data, void *error_ecc,
+                void *correct_data, void *correct_ecc, const size_t size)
+{
+        double_bit_error_data(error_data, correct_data, size);
+        memcpy(error_ecc, correct_ecc, 3);
+}
+
+static void single_bit_error_in_data_and_ecc(void *error_data, void *error_ecc,
+                void *correct_data, void *correct_ecc, const size_t size)
+{
+        single_bit_error_data(error_data, correct_data, size);
+        single_bit_error_ecc(error_ecc, correct_ecc, size);
+}
+
+static void double_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);
+        double_bit_error_ecc(error_ecc, correct_ecc, size);
+}
+
+static int double_bit_error_detect(void *error_data, void *error_ecc,
+                                void *correct_data, const size_t size)
+{
+        unsigned char calc_ecc[3];
+        int ret;
+
+        __nand_calculate_ecc(error_data, size, calc_ecc);
+        ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
+
+        return (ret == -1) ? 0 : -EINVAL;
+}
+
 static const struct nand_ecc_test nand_ecc_test[] = {
         {
                 .name = "no-bit-error",
@@ -138,6 +202,21 @@ static const struct nand_ecc_test nand_ecc_test[] = {
                 .prepare = single_bit_error_in_ecc,
                 .verify = single_bit_error_correct,
         },
+        {
+                .name = "double-bit-error-in-data-detect",
+                .prepare = double_bit_error_in_data,
+                .verify = double_bit_error_detect,
+        },
+        {
+                .name = "single-bit-error-in-data-and-ecc-detect",
+                .prepare = single_bit_error_in_data_and_ecc,
+                .verify = double_bit_error_detect,
+        },
+        {
+                .name = "double-bit-error-in-ecc-detect",
+                .prepare = double_bit_error_in_ecc,
+                .verify = double_bit_error_detect,
+        },
 };
 
 static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data,