drivers/mtd/nand/sunxi_nand_spl.c - manifest_repos/bootloader - Git at Google

 /*
  * Copyright (c) 2014-2015, Antmicro Ltd <www.antmicro.com>
  * Copyright (c) 2015, AW-SOM Technologies <www.aw-som.com>
  *
  * SPDX-License-Identifier:     GPL-2.0+
  */

 #include <asm/arch/clock.h>
 #include <asm/io.h>
 #include <common.h>
 #include <config.h>
 #include <nand.h>

 /* registers */
 #define NFC_CTL                    0x00000000
 #define NFC_ST                     0x00000004
 #define NFC_INT                    0x00000008
 #define NFC_TIMING_CTL             0x0000000C
 #define NFC_TIMING_CFG             0x00000010
 #define NFC_ADDR_LOW               0x00000014
 #define NFC_ADDR_HIGH              0x00000018
 #define NFC_SECTOR_NUM             0x0000001C
 #define NFC_CNT                    0x00000020
 #define NFC_CMD                    0x00000024
 #define NFC_RCMD_SET               0x00000028
 #define NFC_WCMD_SET               0x0000002C
 #define NFC_IO_DATA                0x00000030
 #define NFC_ECC_CTL                0x00000034
 #define NFC_ECC_ST                 0x00000038
 #define NFC_DEBUG                  0x0000003C
 #define NFC_ECC_CNT0               0x00000040
 #define NFC_ECC_CNT1               0x00000044
 #define NFC_ECC_CNT2               0x00000048
 #define NFC_ECC_CNT3               0x0000004C
 #define NFC_USER_DATA_BASE         0x00000050
 #define NFC_EFNAND_STATUS          0x00000090
 #define NFC_SPARE_AREA             0x000000A0
 #define NFC_PATTERN_ID             0x000000A4
 #define NFC_RAM0_BASE              0x00000400
 #define NFC_RAM1_BASE              0x00000800

 #define NFC_CTL_EN                 (1 << 0)
 #define NFC_CTL_RESET              (1 << 1)
 #define NFC_CTL_RAM_METHOD         (1 << 14)
 #define NFC_CTL_PAGE_SIZE_MASK     (0xf << 8)
 #define NFC_CTL_PAGE_SIZE(a)       ((fls(a) - 11) << 8)


 #define NFC_ECC_EN                 (1 << 0)
 #define NFC_ECC_PIPELINE           (1 << 3)
 #define NFC_ECC_EXCEPTION          (1 << 4)
 #define NFC_ECC_BLOCK_SIZE         (1 << 5)
 #define NFC_ECC_RANDOM_EN          (1 << 9)
 #define NFC_ECC_RANDOM_DIRECTION   (1 << 10)


 #define NFC_ADDR_NUM_OFFSET        16
 #define NFC_SEND_ADR               (1 << 19)
 #define NFC_ACCESS_DIR             (1 << 20)
 #define NFC_DATA_TRANS             (1 << 21)
 #define NFC_SEND_CMD1              (1 << 22)
 #define NFC_WAIT_FLAG              (1 << 23)
 #define NFC_SEND_CMD2              (1 << 24)
 #define NFC_SEQ                    (1 << 25)
 #define NFC_DATA_SWAP_METHOD       (1 << 26)
 #define NFC_ROW_AUTO_INC           (1 << 27)
 #define NFC_SEND_CMD3              (1 << 28)
 #define NFC_SEND_CMD4              (1 << 29)

 #define NFC_ST_CMD_INT_FLAG        (1 << 1)
 #define NFC_ST_DMA_INT_FLAG        (1 << 2)

 #define NFC_READ_CMD_OFFSET         0
 #define NFC_RANDOM_READ_CMD0_OFFSET 8
 #define NFC_RANDOM_READ_CMD1_OFFSET 16

 #define NFC_CMD_RNDOUTSTART        0xE0
 #define NFC_CMD_RNDOUT             0x05
 #define NFC_CMD_READSTART          0x30


 #define NFC_PAGE_CMD               (2 << 30)

 #define SUNXI_DMA_CFG_REG0              0x300
 #define SUNXI_DMA_SRC_START_ADDR_REG0   0x304
 #define SUNXI_DMA_DEST_START_ADDRR_REG0 0x308
 #define SUNXI_DMA_DDMA_BC_REG0          0x30C
 #define SUNXI_DMA_DDMA_PARA_REG0        0x318

 #define SUNXI_DMA_DDMA_CFG_REG_LOADING  (1 << 31)
 #define SUNXI_DMA_DDMA_CFG_REG_DMA_DEST_DATA_WIDTH_32 (2 << 25)
 #define SUNXI_DMA_DDMA_CFG_REG_DDMA_DST_DRQ_TYPE_DRAM (1 << 16)
 #define SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_DATA_WIDTH_32 (2 << 9)
 #define SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_ADDR_MODE_IO (1 << 5)
 #define SUNXI_DMA_DDMA_CFG_REG_DDMA_SRC_DRQ_TYPE_NFC (3 << 0)

 #define SUNXI_DMA_DDMA_PARA_REG_SRC_WAIT_CYC (0x0F << 0)
 #define SUNXI_DMA_DDMA_PARA_REG_SRC_BLK_SIZE (0x7F << 8)

 /* minimal "boot0" style NAND support for Allwinner A20 */

 /* random seed used by linux */
 const uint16_t random_seed[128] = {
 	0x2b75, 0x0bd0, 0x5ca3, 0x62d1, 0x1c93, 0x07e9, 0x2162, 0x3a72,
 	0x0d67, 0x67f9, 0x1be7, 0x077d, 0x032f, 0x0dac, 0x2716, 0x2436,
 	0x7922, 0x1510, 0x3860, 0x5287, 0x480f, 0x4252, 0x1789, 0x5a2d,
 	0x2a49, 0x5e10, 0x437f, 0x4b4e, 0x2f45, 0x216e, 0x5cb7, 0x7130,
 	0x2a3f, 0x60e4, 0x4dc9, 0x0ef0, 0x0f52, 0x1bb9, 0x6211, 0x7a56,
 	0x226d, 0x4ea7, 0x6f36, 0x3692, 0x38bf, 0x0c62, 0x05eb, 0x4c55,
 	0x60f4, 0x728c, 0x3b6f, 0x2037, 0x7f69, 0x0936, 0x651a, 0x4ceb,
 	0x6218, 0x79f3, 0x383f, 0x18d9, 0x4f05, 0x5c82, 0x2912, 0x6f17,
 	0x6856, 0x5938, 0x1007, 0x61ab, 0x3e7f, 0x57c2, 0x542f, 0x4f62,
 	0x7454, 0x2eac, 0x7739, 0x42d4, 0x2f90, 0x435a, 0x2e52, 0x2064,
 	0x637c, 0x66ad, 0x2c90, 0x0bad, 0x759c, 0x0029, 0x0986, 0x7126,
 	0x1ca7, 0x1605, 0x386a, 0x27f5, 0x1380, 0x6d75, 0x24c3, 0x0f8e,
 	0x2b7a, 0x1418, 0x1fd1, 0x7dc1, 0x2d8e, 0x43af, 0x2267, 0x7da3,
 	0x4e3d, 0x1338, 0x50db, 0x454d, 0x764d, 0x40a3, 0x42e6, 0x262b,
 	0x2d2e, 0x1aea, 0x2e17, 0x173d, 0x3a6e, 0x71bf, 0x25f9, 0x0a5d,
 	0x7c57, 0x0fbe, 0x46ce, 0x4939, 0x6b17, 0x37bb, 0x3e91, 0x76db,
 };

 /* random seed used for syndrome calls */
 const uint16_t random_seed_syndrome = 0x4a80;

 #define MAX_RETRIES 10

 static int check_value_inner(int offset, int expected_bits,
 				int max_number_of_retries, int negation)
 {
 	int retries = 0;
 	do {
 		int val = readl(offset) & expected_bits;
 		if (negation ? !val : val)
 			return 1;
 		mdelay(1);
 		retries++;
 	} while (retries < max_number_of_retries);

 	return 0;
 }

 static inline int check_value(int offset, int expected_bits,
 				int max_number_of_retries)
 {
 	return check_value_inner(offset, expected_bits,
 					max_number_of_retries, 0);
 }

 static inline int check_value_negated(int offset, int unexpected_bits,
 					int max_number_of_retries)
 {
 	return check_value_inner(offset, unexpected_bits,
 					max_number_of_retries, 1);
 }

 void nand_init(void)
 {
 	uint32_t val;

 	board_nand_init();

 	val = readl(SUNXI_NFC_BASE + NFC_CTL);
 	/* enable and reset CTL */
 	writel(val | NFC_CTL_EN | NFC_CTL_RESET,
 	       SUNXI_NFC_BASE + NFC_CTL);

 	if (!check_value_negated(SUNXI_NFC_BASE + NFC_CTL,
 				 NFC_CTL_RESET, MAX_RETRIES)) {
 		printf("Couldn't initialize nand\n");
 	}

 	/* reset NAND */
 	writel(NFC_ST_CMD_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);
 	writel(NFC_SEND_CMD1 | NFC_WAIT_FLAG | NAND_CMD_RESET,
 	       SUNXI_NFC_BASE + NFC_CMD);

 	if (!check_value(SUNXI_NFC_BASE + NFC_ST, NFC_ST_CMD_INT_FLAG,
 			 MAX_RETRIES)) {
 		printf("Error timeout waiting for nand reset\n");
 		return;
 	}
 	writel(NFC_ST_CMD_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);
 }

 static int nand_read_page(int page_size, int ecc_strength, int ecc_page_size,
 	int addr_cycles, uint32_t real_addr, dma_addr_t dst, int syndrome)
 {
 	uint32_t val;
 	int i, ecc_off = 0;
 	uint16_t ecc_mode = 0;
 	uint16_t rand_seed;
 	uint32_t page;
 	uint16_t column;
 	static const u8 strengths[] = { 16, 24, 28, 32, 40, 48, 56, 60, 64 };

 	for (i = 0; i < ARRAY_SIZE(strengths); i++) {
 		if (ecc_strength == strengths[i]) {
 			ecc_mode = i;
 			break;
 		}
 	}

 	/* HW ECC always request ECC bytes for 1024 bytes blocks */
 	ecc_off = DIV_ROUND_UP(ecc_strength * fls(8 * 1024), 8);
 	/* HW ECC always work with even numbers of ECC bytes */
 	ecc_off += (ecc_off & 1);
 	ecc_off += 4; /* prepad */

 	page = real_addr / page_size;
 	column = real_addr % page_size;

 	if (syndrome)
 		column += (column / ecc_page_size) * ecc_off;

 	/* clear ecc status */
 	writel(0, SUNXI_NFC_BASE + NFC_ECC_ST);

 	/* Choose correct seed */
 	if (syndrome)
 		rand_seed = random_seed_syndrome;
 	else
 		rand_seed = random_seed[page % 128];

 	writel((rand_seed << 16) | NFC_ECC_RANDOM_EN | NFC_ECC_EN
 		| NFC_ECC_PIPELINE | (ecc_mode << 12),
 		SUNXI_NFC_BASE + NFC_ECC_CTL);

 	val = readl(SUNXI_NFC_BASE + NFC_CTL);
 	writel(val | NFC_CTL_RAM_METHOD, SUNXI_NFC_BASE + NFC_CTL);

 	if (!syndrome)
 		writel(page_size + (column / ecc_page_size) * ecc_off,
 		       SUNXI_NFC_BASE + NFC_SPARE_AREA);

 	flush_dcache_range(dst, ALIGN(dst + ecc_page_size, ARCH_DMA_MINALIGN));

 	/* SUNXI_DMA */
 	writel(0x0, SUNXI_DMA_BASE + SUNXI_DMA_CFG_REG0); /* clr dma cmd */
 	/* read from REG_IO_DATA */
 	writel(SUNXI_NFC_BASE + NFC_IO_DATA,
 	       SUNXI_DMA_BASE + SUNXI_DMA_SRC_START_ADDR_REG0);
 	/* read to RAM */
 	writel(dst, SUNXI_DMA_BASE + SUNXI_DMA_DEST_START_ADDRR_REG0);
 	writel(SUNXI_DMA_DDMA_PARA_REG_SRC_WAIT_CYC
 			| SUNXI_DMA_DDMA_PARA_REG_SRC_BLK_SIZE,
 			SUNXI_DMA_BASE + SUNXI_DMA_DDMA_PARA_REG0);
 	writel(ecc_page_size,
 	       SUNXI_DMA_BASE + SUNXI_DMA_DDMA_BC_REG0); /* 1kB */
 	writel(SUNXI_DMA_DDMA_CFG_REG_LOADING
 		| SUNXI_DMA_DDMA_CFG_REG_DMA_DEST_DATA_WIDTH_32
 		| SUNXI_DMA_DDMA_CFG_REG_DDMA_DST_DRQ_TYPE_DRAM
 		| SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_DATA_WIDTH_32
 		| SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_ADDR_MODE_IO
 		| SUNXI_DMA_DDMA_CFG_REG_DDMA_SRC_DRQ_TYPE_NFC,
 		SUNXI_DMA_BASE + SUNXI_DMA_CFG_REG0);

 	writel((NFC_CMD_RNDOUTSTART << NFC_RANDOM_READ_CMD1_OFFSET)
 		| (NFC_CMD_RNDOUT << NFC_RANDOM_READ_CMD0_OFFSET)
 		| (NFC_CMD_READSTART | NFC_READ_CMD_OFFSET), SUNXI_NFC_BASE
 			+ NFC_RCMD_SET);
 	writel(1, SUNXI_NFC_BASE + NFC_SECTOR_NUM);
 	writel(((page & 0xFFFF) << 16) | column,
 	       SUNXI_NFC_BASE + NFC_ADDR_LOW);
 	writel((page >> 16) & 0xFF, SUNXI_NFC_BASE + NFC_ADDR_HIGH);
 	writel(NFC_ST_DMA_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);
 	writel(NFC_SEND_CMD1 | NFC_SEND_CMD2 | NFC_DATA_TRANS |
 		NFC_PAGE_CMD | NFC_WAIT_FLAG |
 		((addr_cycles - 1) << NFC_ADDR_NUM_OFFSET) |
 		NFC_SEND_ADR | NFC_DATA_SWAP_METHOD | (syndrome ? NFC_SEQ : 0),
 		SUNXI_NFC_BASE + NFC_CMD);

 	if (!check_value(SUNXI_NFC_BASE + NFC_ST, NFC_ST_DMA_INT_FLAG,
 			 MAX_RETRIES)) {
 		printf("Error while initializing dma interrupt\n");
 		return -1;
 	}
 	writel(NFC_ST_DMA_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);

 	if (!check_value_negated(SUNXI_DMA_BASE + SUNXI_DMA_CFG_REG0,
 				 SUNXI_DMA_DDMA_CFG_REG_LOADING, MAX_RETRIES)) {
 		printf("Error while waiting for dma transfer to finish\n");
 		return -1;
 	}

 	invalidate_dcache_range(dst,
 			        ALIGN(dst + ecc_page_size, ARCH_DMA_MINALIGN));

 	if (readl(SUNXI_NFC_BASE + NFC_ECC_ST))
 		return -1;

 	return 0;
 }

 static int nand_read_ecc(int page_size, int ecc_strength, int ecc_page_size,
 	int addr_cycles, uint32_t offs, uint32_t size, void *dest, int syndrome)
 {
 	void *end = dest + size;

 	clrsetbits_le32(SUNXI_NFC_BASE + NFC_CTL, NFC_CTL_PAGE_SIZE_MASK,
 			NFC_CTL_PAGE_SIZE(page_size));

 	for ( ;dest < end; dest += ecc_page_size, offs += ecc_page_size) {
 		if (nand_read_page(page_size, ecc_strength, ecc_page_size,
 				   addr_cycles, offs, (dma_addr_t)dest,
 				   syndrome))
 			return -1;
 	}

 	return 0;
 }

 static int nand_read_buffer(uint32_t offs, unsigned int size, void *dest,
 			    int syndrome)
 {
 	const struct {
 		int page_size;
 		int ecc_strength;
 		int ecc_page_size;
 		int addr_cycles;
 	} nand_configs[] = {
 		{  8192, 40, 1024, 5 },
 		{ 16384, 56, 1024, 5 },
 		{  8192, 24, 1024, 5 },
 		{  4096, 24, 1024, 5 },
 	};
 	static int nand_config = -1;
 	int i;

 	if (nand_config == -1) {
 		for (i = 0; i < ARRAY_SIZE(nand_configs); i++) {
 			debug("nand: trying page %d ecc %d / %d addr %d: ",
 			      nand_configs[i].page_size,
 			      nand_configs[i].ecc_strength,
 			      nand_configs[i].ecc_page_size,
 			      nand_configs[i].addr_cycles);
 			if (nand_read_ecc(nand_configs[i].page_size,
 					  nand_configs[i].ecc_strength,
 					  nand_configs[i].ecc_page_size,
 					  nand_configs[i].addr_cycles,
 					  offs, size, dest, syndrome) == 0) {
 				debug("success\n");
 				nand_config = i;
 				return 0;
 			}
 			debug("failed\n");
 		}
 		return -1;
 	}

 	return nand_read_ecc(nand_configs[nand_config].page_size,
 			     nand_configs[nand_config].ecc_strength,
 			     nand_configs[nand_config].ecc_page_size,
 			     nand_configs[nand_config].addr_cycles,
 			     offs, size, dest, syndrome);
 }

 int nand_spl_load_image(uint32_t offs, unsigned int size, void *dest)
 {
 #if CONFIG_SYS_NAND_U_BOOT_OFFS == CONFIG_SPL_PAD_TO
 	/*
 	 * u-boot-dtb.bin appended to SPL, use syndrome (like the BROM does)
 	 * and try different erase block sizes to find the backup.
 	 */
 	const uint32_t boot_offsets[] = {
 		0 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
 		1 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
 		2 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
 		4 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
 	};
 	const int syndrome = 1;
 #else
 	/*
 	 * u-boot-dtb.bin on its own partition, do not use syndrome, u-boot
 	 * partition sits after 2 eraseblocks (spl, spl-backup), look for
 	 * backup u-boot 1 erase block further.
 	 */
 	const uint32_t eraseblock_size = CONFIG_SYS_NAND_U_BOOT_OFFS / 2;
 	const uint32_t boot_offsets[] = {
 		CONFIG_SYS_NAND_U_BOOT_OFFS,
 		CONFIG_SYS_NAND_U_BOOT_OFFS + eraseblock_size,
 	};
 	const int syndrome = 0;
 #endif
 	int i;

 	if (offs == CONFIG_SYS_NAND_U_BOOT_OFFS) {
 		for (i = 0; i < ARRAY_SIZE(boot_offsets); i++) {
 			if (nand_read_buffer(boot_offsets[i], size,
 					     dest, syndrome) == 0)
 				return 0;
 		}
 		return -1;
 	}

 	return nand_read_buffer(offs, size, dest, syndrome);
 }

 void nand_deselect(void)
 {
 	struct sunxi_ccm_reg *const ccm =
 		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;

 	clrbits_le32(&ccm->ahb_gate0, (CLK_GATE_OPEN << AHB_GATE_OFFSET_NAND0));
 #ifdef CONFIG_MACH_SUN9I
 	clrbits_le32(&ccm->ahb_gate1, (1 << AHB_GATE_OFFSET_DMA));
 #else
 	clrbits_le32(&ccm->ahb_gate0, (1 << AHB_GATE_OFFSET_DMA));
 #endif
 	clrbits_le32(&ccm->nand0_clk_cfg, CCM_NAND_CTRL_ENABLE | AHB_DIV_1);
 }
	/*
	* Copyright (c) 2014-2015, Antmicro Ltd <www.antmicro.com>
	* Copyright (c) 2015, AW-SOM Technologies <www.aw-som.com>
	*
	* SPDX-License-Identifier: GPL-2.0+
	*/

	#include <asm/arch/clock.h>
	#include <asm/io.h>
	#include <common.h>
	#include <config.h>
	#include <nand.h>

	/* registers */
	#define NFC_CTL 0x00000000
	#define NFC_ST 0x00000004
	#define NFC_INT 0x00000008
	#define NFC_TIMING_CTL 0x0000000C
	#define NFC_TIMING_CFG 0x00000010
	#define NFC_ADDR_LOW 0x00000014
	#define NFC_ADDR_HIGH 0x00000018
	#define NFC_SECTOR_NUM 0x0000001C
	#define NFC_CNT 0x00000020
	#define NFC_CMD 0x00000024
	#define NFC_RCMD_SET 0x00000028
	#define NFC_WCMD_SET 0x0000002C
	#define NFC_IO_DATA 0x00000030
	#define NFC_ECC_CTL 0x00000034
	#define NFC_ECC_ST 0x00000038
	#define NFC_DEBUG 0x0000003C
	#define NFC_ECC_CNT0 0x00000040
	#define NFC_ECC_CNT1 0x00000044
	#define NFC_ECC_CNT2 0x00000048
	#define NFC_ECC_CNT3 0x0000004C
	#define NFC_USER_DATA_BASE 0x00000050
	#define NFC_EFNAND_STATUS 0x00000090
	#define NFC_SPARE_AREA 0x000000A0
	#define NFC_PATTERN_ID 0x000000A4
	#define NFC_RAM0_BASE 0x00000400
	#define NFC_RAM1_BASE 0x00000800

	#define NFC_CTL_EN (1 << 0)
	#define NFC_CTL_RESET (1 << 1)
	#define NFC_CTL_RAM_METHOD (1 << 14)
	#define NFC_CTL_PAGE_SIZE_MASK (0xf << 8)
	#define NFC_CTL_PAGE_SIZE(a) ((fls(a) - 11) << 8)


	#define NFC_ECC_EN (1 << 0)
	#define NFC_ECC_PIPELINE (1 << 3)
	#define NFC_ECC_EXCEPTION (1 << 4)
	#define NFC_ECC_BLOCK_SIZE (1 << 5)
	#define NFC_ECC_RANDOM_EN (1 << 9)
	#define NFC_ECC_RANDOM_DIRECTION (1 << 10)


	#define NFC_ADDR_NUM_OFFSET 16
	#define NFC_SEND_ADR (1 << 19)
	#define NFC_ACCESS_DIR (1 << 20)
	#define NFC_DATA_TRANS (1 << 21)
	#define NFC_SEND_CMD1 (1 << 22)
	#define NFC_WAIT_FLAG (1 << 23)
	#define NFC_SEND_CMD2 (1 << 24)
	#define NFC_SEQ (1 << 25)
	#define NFC_DATA_SWAP_METHOD (1 << 26)
	#define NFC_ROW_AUTO_INC (1 << 27)
	#define NFC_SEND_CMD3 (1 << 28)
	#define NFC_SEND_CMD4 (1 << 29)

	#define NFC_ST_CMD_INT_FLAG (1 << 1)
	#define NFC_ST_DMA_INT_FLAG (1 << 2)

	#define NFC_READ_CMD_OFFSET 0
	#define NFC_RANDOM_READ_CMD0_OFFSET 8
	#define NFC_RANDOM_READ_CMD1_OFFSET 16

	#define NFC_CMD_RNDOUTSTART 0xE0
	#define NFC_CMD_RNDOUT 0x05
	#define NFC_CMD_READSTART 0x30


	#define NFC_PAGE_CMD (2 << 30)

	#define SUNXI_DMA_CFG_REG0 0x300
	#define SUNXI_DMA_SRC_START_ADDR_REG0 0x304
	#define SUNXI_DMA_DEST_START_ADDRR_REG0 0x308
	#define SUNXI_DMA_DDMA_BC_REG0 0x30C
	#define SUNXI_DMA_DDMA_PARA_REG0 0x318

	#define SUNXI_DMA_DDMA_CFG_REG_LOADING (1 << 31)
	#define SUNXI_DMA_DDMA_CFG_REG_DMA_DEST_DATA_WIDTH_32 (2 << 25)
	#define SUNXI_DMA_DDMA_CFG_REG_DDMA_DST_DRQ_TYPE_DRAM (1 << 16)
	#define SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_DATA_WIDTH_32 (2 << 9)
	#define SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_ADDR_MODE_IO (1 << 5)
	#define SUNXI_DMA_DDMA_CFG_REG_DDMA_SRC_DRQ_TYPE_NFC (3 << 0)

	#define SUNXI_DMA_DDMA_PARA_REG_SRC_WAIT_CYC (0x0F << 0)
	#define SUNXI_DMA_DDMA_PARA_REG_SRC_BLK_SIZE (0x7F << 8)

	/* minimal "boot0" style NAND support for Allwinner A20 */

	/* random seed used by linux */
	const uint16_t random_seed[128] = {
	0x2b75, 0x0bd0, 0x5ca3, 0x62d1, 0x1c93, 0x07e9, 0x2162, 0x3a72,
	0x0d67, 0x67f9, 0x1be7, 0x077d, 0x032f, 0x0dac, 0x2716, 0x2436,
	0x7922, 0x1510, 0x3860, 0x5287, 0x480f, 0x4252, 0x1789, 0x5a2d,
	0x2a49, 0x5e10, 0x437f, 0x4b4e, 0x2f45, 0x216e, 0x5cb7, 0x7130,
	0x2a3f, 0x60e4, 0x4dc9, 0x0ef0, 0x0f52, 0x1bb9, 0x6211, 0x7a56,
	0x226d, 0x4ea7, 0x6f36, 0x3692, 0x38bf, 0x0c62, 0x05eb, 0x4c55,
	0x60f4, 0x728c, 0x3b6f, 0x2037, 0x7f69, 0x0936, 0x651a, 0x4ceb,
	0x6218, 0x79f3, 0x383f, 0x18d9, 0x4f05, 0x5c82, 0x2912, 0x6f17,
	0x6856, 0x5938, 0x1007, 0x61ab, 0x3e7f, 0x57c2, 0x542f, 0x4f62,
	0x7454, 0x2eac, 0x7739, 0x42d4, 0x2f90, 0x435a, 0x2e52, 0x2064,
	0x637c, 0x66ad, 0x2c90, 0x0bad, 0x759c, 0x0029, 0x0986, 0x7126,
	0x1ca7, 0x1605, 0x386a, 0x27f5, 0x1380, 0x6d75, 0x24c3, 0x0f8e,
	0x2b7a, 0x1418, 0x1fd1, 0x7dc1, 0x2d8e, 0x43af, 0x2267, 0x7da3,
	0x4e3d, 0x1338, 0x50db, 0x454d, 0x764d, 0x40a3, 0x42e6, 0x262b,
	0x2d2e, 0x1aea, 0x2e17, 0x173d, 0x3a6e, 0x71bf, 0x25f9, 0x0a5d,
	0x7c57, 0x0fbe, 0x46ce, 0x4939, 0x6b17, 0x37bb, 0x3e91, 0x76db,
	};

	/* random seed used for syndrome calls */
	const uint16_t random_seed_syndrome = 0x4a80;

	#define MAX_RETRIES 10

	static int check_value_inner(int offset, int expected_bits,
	int max_number_of_retries, int negation)
	{
	int retries = 0;
	do {
	int val = readl(offset) & expected_bits;
	if (negation ? !val : val)
	return 1;
	mdelay(1);
	retries++;
	} while (retries < max_number_of_retries);

	return 0;
	}

	static inline int check_value(int offset, int expected_bits,
	int max_number_of_retries)
	{
	return check_value_inner(offset, expected_bits,
	max_number_of_retries, 0);
	}

	static inline int check_value_negated(int offset, int unexpected_bits,
	int max_number_of_retries)
	{
	return check_value_inner(offset, unexpected_bits,
	max_number_of_retries, 1);
	}

	void nand_init(void)
	{
	uint32_t val;

	board_nand_init();

	val = readl(SUNXI_NFC_BASE + NFC_CTL);
	/* enable and reset CTL */
	writel(val \| NFC_CTL_EN \| NFC_CTL_RESET,
	SUNXI_NFC_BASE + NFC_CTL);

	if (!check_value_negated(SUNXI_NFC_BASE + NFC_CTL,
	NFC_CTL_RESET, MAX_RETRIES)) {
	printf("Couldn't initialize nand\n");
	}

	/* reset NAND */
	writel(NFC_ST_CMD_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);
	writel(NFC_SEND_CMD1 \| NFC_WAIT_FLAG \| NAND_CMD_RESET,
	SUNXI_NFC_BASE + NFC_CMD);

	if (!check_value(SUNXI_NFC_BASE + NFC_ST, NFC_ST_CMD_INT_FLAG,
	MAX_RETRIES)) {
	printf("Error timeout waiting for nand reset\n");
	return;
	}
	writel(NFC_ST_CMD_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);
	}

	static int nand_read_page(int page_size, int ecc_strength, int ecc_page_size,
	int addr_cycles, uint32_t real_addr, dma_addr_t dst, int syndrome)
	{
	uint32_t val;
	int i, ecc_off = 0;
	uint16_t ecc_mode = 0;
	uint16_t rand_seed;
	uint32_t page;
	uint16_t column;
	static const u8 strengths[] = { 16, 24, 28, 32, 40, 48, 56, 60, 64 };

	for (i = 0; i < ARRAY_SIZE(strengths); i++) {
	if (ecc_strength == strengths[i]) {
	ecc_mode = i;
	break;
	}
	}

	/* HW ECC always request ECC bytes for 1024 bytes blocks */
	ecc_off = DIV_ROUND_UP(ecc_strength * fls(8 * 1024), 8);
	/* HW ECC always work with even numbers of ECC bytes */
	ecc_off += (ecc_off & 1);
	ecc_off += 4; /* prepad */

	page = real_addr / page_size;
	column = real_addr % page_size;

	if (syndrome)
	column += (column / ecc_page_size) * ecc_off;

	/* clear ecc status */
	writel(0, SUNXI_NFC_BASE + NFC_ECC_ST);

	/* Choose correct seed */
	if (syndrome)
	rand_seed = random_seed_syndrome;
	else
	rand_seed = random_seed[page % 128];

	writel((rand_seed << 16) \| NFC_ECC_RANDOM_EN \| NFC_ECC_EN
	\| NFC_ECC_PIPELINE \| (ecc_mode << 12),
	SUNXI_NFC_BASE + NFC_ECC_CTL);

	val = readl(SUNXI_NFC_BASE + NFC_CTL);
	writel(val \| NFC_CTL_RAM_METHOD, SUNXI_NFC_BASE + NFC_CTL);

	if (!syndrome)
	writel(page_size + (column / ecc_page_size) * ecc_off,
	SUNXI_NFC_BASE + NFC_SPARE_AREA);

	flush_dcache_range(dst, ALIGN(dst + ecc_page_size, ARCH_DMA_MINALIGN));

	/* SUNXI_DMA */
	writel(0x0, SUNXI_DMA_BASE + SUNXI_DMA_CFG_REG0); /* clr dma cmd */
	/* read from REG_IO_DATA */
	writel(SUNXI_NFC_BASE + NFC_IO_DATA,
	SUNXI_DMA_BASE + SUNXI_DMA_SRC_START_ADDR_REG0);
	/* read to RAM */
	writel(dst, SUNXI_DMA_BASE + SUNXI_DMA_DEST_START_ADDRR_REG0);
	writel(SUNXI_DMA_DDMA_PARA_REG_SRC_WAIT_CYC
	\| SUNXI_DMA_DDMA_PARA_REG_SRC_BLK_SIZE,
	SUNXI_DMA_BASE + SUNXI_DMA_DDMA_PARA_REG0);
	writel(ecc_page_size,
	SUNXI_DMA_BASE + SUNXI_DMA_DDMA_BC_REG0); /* 1kB */
	writel(SUNXI_DMA_DDMA_CFG_REG_LOADING
	\| SUNXI_DMA_DDMA_CFG_REG_DMA_DEST_DATA_WIDTH_32
	\| SUNXI_DMA_DDMA_CFG_REG_DDMA_DST_DRQ_TYPE_DRAM
	\| SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_DATA_WIDTH_32
	\| SUNXI_DMA_DDMA_CFG_REG_DMA_SRC_ADDR_MODE_IO
	\| SUNXI_DMA_DDMA_CFG_REG_DDMA_SRC_DRQ_TYPE_NFC,
	SUNXI_DMA_BASE + SUNXI_DMA_CFG_REG0);

	writel((NFC_CMD_RNDOUTSTART << NFC_RANDOM_READ_CMD1_OFFSET)
	\| (NFC_CMD_RNDOUT << NFC_RANDOM_READ_CMD0_OFFSET)
	\| (NFC_CMD_READSTART \| NFC_READ_CMD_OFFSET), SUNXI_NFC_BASE
	+ NFC_RCMD_SET);
	writel(1, SUNXI_NFC_BASE + NFC_SECTOR_NUM);
	writel(((page & 0xFFFF) << 16) \| column,
	SUNXI_NFC_BASE + NFC_ADDR_LOW);
	writel((page >> 16) & 0xFF, SUNXI_NFC_BASE + NFC_ADDR_HIGH);
	writel(NFC_ST_DMA_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);
	writel(NFC_SEND_CMD1 \| NFC_SEND_CMD2 \| NFC_DATA_TRANS \|
	NFC_PAGE_CMD \| NFC_WAIT_FLAG \|
	((addr_cycles - 1) << NFC_ADDR_NUM_OFFSET) \|
	NFC_SEND_ADR \| NFC_DATA_SWAP_METHOD \| (syndrome ? NFC_SEQ : 0),
	SUNXI_NFC_BASE + NFC_CMD);

	if (!check_value(SUNXI_NFC_BASE + NFC_ST, NFC_ST_DMA_INT_FLAG,
	MAX_RETRIES)) {
	printf("Error while initializing dma interrupt\n");
	return -1;
	}
	writel(NFC_ST_DMA_INT_FLAG, SUNXI_NFC_BASE + NFC_ST);

	if (!check_value_negated(SUNXI_DMA_BASE + SUNXI_DMA_CFG_REG0,
	SUNXI_DMA_DDMA_CFG_REG_LOADING, MAX_RETRIES)) {
	printf("Error while waiting for dma transfer to finish\n");
	return -1;
	}

	invalidate_dcache_range(dst,
	ALIGN(dst + ecc_page_size, ARCH_DMA_MINALIGN));

	if (readl(SUNXI_NFC_BASE + NFC_ECC_ST))
	return -1;

	return 0;
	}

	static int nand_read_ecc(int page_size, int ecc_strength, int ecc_page_size,
	int addr_cycles, uint32_t offs, uint32_t size, void *dest, int syndrome)
	{
	void *end = dest + size;

	clrsetbits_le32(SUNXI_NFC_BASE + NFC_CTL, NFC_CTL_PAGE_SIZE_MASK,
	NFC_CTL_PAGE_SIZE(page_size));

	for ( ;dest < end; dest += ecc_page_size, offs += ecc_page_size) {
	if (nand_read_page(page_size, ecc_strength, ecc_page_size,
	addr_cycles, offs, (dma_addr_t)dest,
	syndrome))
	return -1;
	}

	return 0;
	}

	static int nand_read_buffer(uint32_t offs, unsigned int size, void *dest,
	int syndrome)
	{
	const struct {
	int page_size;
	int ecc_strength;
	int ecc_page_size;
	int addr_cycles;
	} nand_configs[] = {
	{ 8192, 40, 1024, 5 },
	{ 16384, 56, 1024, 5 },
	{ 8192, 24, 1024, 5 },
	{ 4096, 24, 1024, 5 },
	};
	static int nand_config = -1;
	int i;

	if (nand_config == -1) {
	for (i = 0; i < ARRAY_SIZE(nand_configs); i++) {
	debug("nand: trying page %d ecc %d / %d addr %d: ",
	nand_configs[i].page_size,
	nand_configs[i].ecc_strength,
	nand_configs[i].ecc_page_size,
	nand_configs[i].addr_cycles);
	if (nand_read_ecc(nand_configs[i].page_size,
	nand_configs[i].ecc_strength,
	nand_configs[i].ecc_page_size,
	nand_configs[i].addr_cycles,
	offs, size, dest, syndrome) == 0) {
	debug("success\n");
	nand_config = i;
	return 0;
	}
	debug("failed\n");
	}
	return -1;
	}

	return nand_read_ecc(nand_configs[nand_config].page_size,
	nand_configs[nand_config].ecc_strength,
	nand_configs[nand_config].ecc_page_size,
	nand_configs[nand_config].addr_cycles,
	offs, size, dest, syndrome);
	}

	int nand_spl_load_image(uint32_t offs, unsigned int size, void *dest)
	{
	#if CONFIG_SYS_NAND_U_BOOT_OFFS == CONFIG_SPL_PAD_TO
	/*
	* u-boot-dtb.bin appended to SPL, use syndrome (like the BROM does)
	* and try different erase block sizes to find the backup.
	*/
	const uint32_t boot_offsets[] = {
	0 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
	1 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
	2 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
	4 * 1024 * 1024 + CONFIG_SYS_NAND_U_BOOT_OFFS,
	};
	const int syndrome = 1;
	#else
	/*
	* u-boot-dtb.bin on its own partition, do not use syndrome, u-boot
	* partition sits after 2 eraseblocks (spl, spl-backup), look for
	* backup u-boot 1 erase block further.
	*/
	const uint32_t eraseblock_size = CONFIG_SYS_NAND_U_BOOT_OFFS / 2;
	const uint32_t boot_offsets[] = {
	CONFIG_SYS_NAND_U_BOOT_OFFS,
	CONFIG_SYS_NAND_U_BOOT_OFFS + eraseblock_size,
	};
	const int syndrome = 0;
	#endif
	int i;

	if (offs == CONFIG_SYS_NAND_U_BOOT_OFFS) {
	for (i = 0; i < ARRAY_SIZE(boot_offsets); i++) {
	if (nand_read_buffer(boot_offsets[i], size,
	dest, syndrome) == 0)
	return 0;
	}
	return -1;
	}

	return nand_read_buffer(offs, size, dest, syndrome);
	}

	void nand_deselect(void)
	{
	struct sunxi_ccm_reg *const ccm =
	(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;

	clrbits_le32(&ccm->ahb_gate0, (CLK_GATE_OPEN << AHB_GATE_OFFSET_NAND0));
	#ifdef CONFIG_MACH_SUN9I
	clrbits_le32(&ccm->ahb_gate1, (1 << AHB_GATE_OFFSET_DMA));
	#else
	clrbits_le32(&ccm->ahb_gate0, (1 << AHB_GATE_OFFSET_DMA));
	#endif
	clrbits_le32(&ccm->nand0_clk_cfg, CCM_NAND_CTRL_ENABLE \| AHB_DIV_1);
	}