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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/random.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/mtd/nand_ecc.h>
/*
* Test the implementation for software ECC
*
* No actual MTD device is needed, So we don't need to warry about losing
* important data by human error.
*
* This covers possible patterns of corruption which can be reliably corrected
* or detected.
*/
#if defined(CONFIG_MTD_NAND) || defined(CONFIG_MTD_NAND_MODULE)
struct nand_ecc_test {
const char *name;
void (*prepare)(void *, void *, void *, void *, const size_t);
int (*verify)(void *, void *, void *, const size_t);
};
/*
* The reason for this __change_bit_le() instead of __change_bit() is to inject
* bit error properly within the region which is not a multiple of
* sizeof(unsigned long) on big-endian systems
*/
#ifdef __LITTLE_ENDIAN
#define __change_bit_le(nr, addr) __change_bit(nr, addr)
#elif defined(__BIG_ENDIAN)
#define __change_bit_le(nr, addr) \
__change_bit((nr) ^ ((BITS_PER_LONG - 1) & ~0x7), addr)
#else
#error "Unknown byte order"
#endif
static void single_bit_error_data(void *error_data, void *correct_data,
size_t size)
{
unsigned int offset = random32() % (size * BITS_PER_BYTE);
memcpy(error_data, correct_data, size);
__change_bit_le(offset, error_data);
}
static void no_bit_error(void *error_data, void *error_ecc,
void *correct_data, void *correct_ecc, const size_t size)
{
memcpy(error_data, correct_data, size);
memcpy(error_ecc, correct_ecc, 3);
}
static int no_bit_error_verify(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);
if (ret == 0 && !memcmp(correct_data, error_data, size))
return 0;
return -EINVAL;
}
static void single_bit_error_in_data(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);
memcpy(error_ecc, correct_ecc, 3);
}
static int single_bit_error_correct(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);
if (ret == 1 && !memcmp(correct_data, error_data, size))
return 0;
return -EINVAL;
}
static const struct nand_ecc_test nand_ecc_test[] = {
{
.name = "no-bit-error",
.prepare = no_bit_error,
.verify = no_bit_error_verify,
},
{
.name = "single-bit-error-in-data-correct",
.prepare = single_bit_error_in_data,
.verify = single_bit_error_correct,
},
};
static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data,
void *correct_ecc, const size_t size)
{
pr_info("hexdump of error data:\n");
print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
error_data, size, false);
print_hex_dump(KERN_INFO, "hexdump of error ecc: ",
DUMP_PREFIX_NONE, 16, 1, error_ecc, 3, false);
pr_info("hexdump of correct data:\n");
print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
correct_data, size, false);
print_hex_dump(KERN_INFO, "hexdump of correct ecc: ",
DUMP_PREFIX_NONE, 16, 1, correct_ecc, 3, false);
}
static int nand_ecc_test_run(const size_t size)
{
int i;
int err = 0;
void *error_data;
void *error_ecc;
void *correct_data;
void *correct_ecc;
error_data = kmalloc(size, GFP_KERNEL);
error_ecc = kmalloc(3, GFP_KERNEL);
correct_data = kmalloc(size, GFP_KERNEL);
correct_ecc = kmalloc(3, GFP_KERNEL);
if (!error_data || !error_ecc || !correct_data || !correct_ecc) {
err = -ENOMEM;
goto error;
}
get_random_bytes(correct_data, size);
__nand_calculate_ecc(correct_data, size, correct_ecc);
for (i = 0; i < ARRAY_SIZE(nand_ecc_test); i++) {
nand_ecc_test[i].prepare(error_data, error_ecc,
correct_data, correct_ecc, size);
err = nand_ecc_test[i].verify(error_data, error_ecc,
correct_data, size);
if (err) {
pr_err("mtd_nandecctest: not ok - %s-%zd\n",
nand_ecc_test[i].name, size);
dump_data_ecc(error_data, error_ecc,
correct_data, correct_ecc, size);
break;
}
pr_info("mtd_nandecctest: ok - %s-%zd\n",
nand_ecc_test[i].name, size);
}
error:
kfree(error_data);
kfree(error_ecc);
kfree(correct_data);
kfree(correct_ecc);
return err;
}
#else
static int nand_ecc_test_run(const size_t size)
{
return 0;
}
#endif
static int __init ecc_test_init(void)
{
int err;
err = nand_ecc_test_run(256);
if (err)
return err;
return nand_ecc_test_run(512);
}
static void __exit ecc_test_exit(void)
{
}
module_init(ecc_test_init);
module_exit(ecc_test_exit);
MODULE_DESCRIPTION("NAND ECC function test module");
MODULE_AUTHOR("Akinobu Mita");
MODULE_LICENSE("GPL");
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