#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/jiffies.h>
#include <linux/mtd/nand_ecc.h>

#if defined(CONFIG_MTD_NAND) || defined(CONFIG_MTD_NAND_MODULE)

static void inject_single_bit_error(void *data, size_t size)
{
	unsigned long offset = random32() % (size * BITS_PER_BYTE);

	__change_bit(offset, data);
}

static unsigned char data[512];
static unsigned char error_data[512];

static int nand_ecc_test(const size_t size)
{
	unsigned char code[3];
	unsigned char error_code[3];
	char testname[30];

	BUG_ON(sizeof(data) < size);

	sprintf(testname, "nand-ecc-%zu", size);

	get_random_bytes(data, size);

	memcpy(error_data, data, size);
	inject_single_bit_error(error_data, size);

	__nand_calculate_ecc(data, size, code);
	__nand_calculate_ecc(error_data, size, error_code);
	__nand_correct_data(error_data, code, error_code, size);

	if (!memcmp(data, error_data, size)) {
		printk(KERN_INFO "mtd_nandecctest: ok - %s\n", testname);
		return 0;
	}

	printk(KERN_ERR "mtd_nandecctest: not ok - %s\n", testname);

	printk(KERN_DEBUG "hexdump of data:\n");
	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 16, 4,
			data, size, false);
	printk(KERN_DEBUG "hexdump of error data:\n");
	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 16, 4,
			error_data, size, false);

	return -1;
}

#else

static int nand_ecc_test(const size_t size)
{
	return 0;
}

#endif

static int __init ecc_test_init(void)
{
	srandom32(jiffies);

	nand_ecc_test(256);
	nand_ecc_test(512);

	return 0;
}

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");