linux的NAND Flash驱动位于drivers/mtd/nand子文件夹下：
nand_base.c-->定义通用的nand flash基本操作函数，如读写page，可自己重写这些函数
nand_bbt.c-->与坏块管理有关的函数和结构体
nand_ids.c-->nand_flash_ids[]（芯片ID）和nand_manuf_ids[]（厂商ID）
nand_ecc.c-->软件ECC代码，若系统支持硬件ECC。则不用理会这个文件
pl353_nand.c-->pl353 nand flash控制器的驱动代码
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/irq.h>
#include <linux/memory/pl353-smc.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/nand_ecc.h>
#include <linux/mtd/partitions.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#define PL353_NAND_DRIVER_NAME "pl353-nand"
/* NAND flash driver defines */
#define PL353_NAND_CMD_PHASE 1 /* End command valid in command phase */
#define PL353_NAND_DATA_PHASE 2 /* End command valid in data phase */
#define PL353_NAND_ECC_SIZE 512 /* Size of data for ECC operation */
/* Flash memory controller operating parameters */
#define PL353_NAND_ECC_CONFIG (BIT(4) | /* ECC read at end of page */
(0 << 5)) /* No Jumping */
/* AXI Address definitions */
#define START_CMD_SHIFT 3
#define END_CMD_SHIFT 11
#define END_CMD_VALID_SHIFT 20
#define ADDR_CYCLES_SHIFT 21
#define CLEAR_CS_SHIFT 21
#define ECC_LAST_SHIFT 10
#define COMMAND_PHASE (0 << 19)
#define DATA_PHASE BIT(19)
#define PL353_NAND_ECC_LAST BIT(ECC_LAST_SHIFT) /* Set ECC_Last */
#define PL353_NAND_CLEAR_CS BIT(CLEAR_CS_SHIFT) /* Clear chip select */
#define ONDIE_ECC_FEATURE_ADDR 0x90
#define PL353_NAND_ECC_BUSY_TIMEOUT (1 * HZ)
#define PL353_NAND_DEV_BUSY_TIMEOUT (1 * HZ)
#define PL353_NAND_LAST_TRANSFER_LENGTH 4
/* Inline function for the NAND controller register write */
static inline void pl353_nand_write32(void __iomem *addr, u32 val)
{
writel_relaxed((val), (addr));
}
/**
* struct pl353_nand_command_format - Defines NAND flash command format
* @start_cmd: First cycle command (Start command)
* @end_cmd: Second cycle command (Last command)
* @addr_cycles: Number of address cycles required to send the address
* @end_cmd_valid: The second cycle command is valid for cmd or data phase
*/
struct pl353_nand_command_format {
int start_cmd;
int end_cmd;
u8 addr_cycles;
u8 end_cmd_valid;
};
/**
* struct pl353_nand_info - Defines the NAND flash driver instance
* @chip: NAND chip information structure
* @mtd: MTD information structure
* @parts: Pointer to the mtd_partition structure
* @nand_base: Virtual address of the NAND flash device
* @end_cmd_pending: End command is pending
* @end_cmd: End command
*/
struct pl353_nand_info {
struct nand_chip chip;
struct mtd_info mtd;
struct mtd_partition *parts;
void __iomem *nand_base;
unsigned long end_cmd_pending;
unsigned long end_cmd;
};
/*
* The NAND flash operations command format
*/
static const struct pl353_nand_command_format pl353_nand_commands[] = {
{NAND_CMD_READ0, NAND_CMD_READSTART, 5, PL353_NAND_CMD_PHASE}, //read data
{NAND_CMD_RNDOUT, NAND_CMD_RNDOUTSTART, 2, PL353_NAND_CMD_PHASE}, //random Data output
{NAND_CMD_READID, NAND_CMD_NONE, 1, NAND_CMD_NONE}, //read ID
{NAND_CMD_STATUS, NAND_CMD_NONE, 0, NAND_CMD_NONE}, //read status
{NAND_CMD_SEQIN, NAND_CMD_PAGEPROG, 5, PL353_NAND_DATA_PHASE}, //page program
{NAND_CMD_RNDIN, NAND_CMD_NONE, 2, NAND_CMD_NONE}, //random data input
{NAND_CMD_ERASE1, NAND_CMD_ERASE2, 3, PL353_NAND_CMD_PHASE}, //erase block
{NAND_CMD_RESET, NAND_CMD_NONE, 0, NAND_CMD_NONE}, //reset
{NAND_CMD_PARAM, NAND_CMD_NONE, 1, NAND_CMD_NONE},
{NAND_CMD_GET_FEATURES, NAND_CMD_NONE, 1, NAND_CMD_NONE},
{NAND_CMD_SET_FEATURES, NAND_CMD_NONE, 1, NAND_CMD_NONE},
{NAND_CMD_NONE, NAND_CMD_NONE, 0, 0},
/* Add all the flash commands supported by the flash device and Linux */
/*
* The cache program command is not supported by driver because driver
* cant differentiate between page program and cached page program from
* start command, these commands can be differentiated through end
* command, which doesn't fit in to the driver design. The cache program
* command is not supported by NAND subsystem also, look at 1612 line
* number (in nand_write_page function) of nand_base.c file.
* {NAND_CMD_SEQIN, NAND_CMD_CACHEDPROG, 5, PL353_NAND_YES},
*/
};
/* Define default oob placement schemes for large and small page devices */
//一般一页中每512字节会相应16字节的OOB空间
static struct nand_ecclayout nand_oob_16 = { //16表示OOB大小为16B，即页大小为512B时。使用这个ecclayout
.eccbytes = 3, //对于pl353每512B数据产生3B的ecc校验值
.eccpos = {0, 1, 2}, //ecc校验值在OOB中存放的位置
.oobfree = {
{.offset = 8, //空暇OOB的起始位置
. length = 8} }
};
static struct nand_ecclayout nand_oob_64 = { //页大小为2KB时。使用这个ecclayout
.eccbytes = 12, //3*4
.eccpos = {
52, 53, 54, 55, 56, 57,
58, 59, 60, 61, 62, 63},
.oobfree = {
{.offset = 2,
.length = 50} }
};
//ondie类型的nand flash使用这个ecclayout,不太清楚ondie是什么意思？
static struct nand_ecclayout ondie_nand_oob_64 = {
.eccbytes = 32,
.eccpos = {
8, 9, 10, 11, 12, 13, 14, 15,
24, 25, 26, 27, 28, 29, 30, 31,
40, 41, 42, 43, 44, 45, 46, 47,
56, 57, 58, 59, 60, 61, 62, 63
},
.oobfree = {
{ .offset = 4, .length = 4 },
{ .offset = 20, .length = 4 },
{ .offset = 36, .length = 4 },
{ .offset = 52, .length = 4 }
}
};
/* Generic flash bbt decriptors */
static uint8_t bbt_pattern[] = { 'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = { '1', 't', 'b', 'B' };
static struct nand_bbt_descr bbt_main_descr = {
.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
.offs = 4,
.len = 4,
.veroffs = 20,
.maxblocks = 4,
.pattern = bbt_pattern
};
static struct nand_bbt_descr bbt_mirror_descr = {
.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE
| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
.offs = 4,
.len = 4,
.veroffs = 20,
.maxblocks = 4,
.pattern = mirror_pattern
};
/**
* pl353_nand_calculate_hwecc - Calculate Hardware ECC
* @mtd: Pointer to the mtd_info structure
* @data: Pointer to the page data
* @ecc_code: Pointer to the ECC buffer where ECC data needs to be stored
*
* This function retrieves the Hardware ECC data from the controller and returns
* ECC data back to the MTD subsystem.
*
* Return: 0 on success or error value on failure
*/
//从ecc寄存器中获取的ecc值会存放在ecc_code地址空间中
static int pl353_nand_calculate_hwecc(struct mtd_info *mtd,
const u8 *data, u8 *ecc_code)
{
u32 ecc_value, ecc_status;
u8 ecc_reg, ecc_byte;
unsigned long timeout = jiffies + PL353_NAND_ECC_BUSY_TIMEOUT;
/* Wait till the ECC operation is complete or timeout */
do {
if (pl353_smc_ecc_is_busy())
cpu_relax();
else
break;
} while (!time_after_eq(jiffies, timeout));
if (time_after_eq(jiffies, timeout)) {
pr_err("%s timed out
", __func__);
return -ETIMEDOUT;
}
for (ecc_reg = 0; ecc_reg < 4; ecc_reg++) {
/* Read ECC value for each block */
ecc_value = pl353_smc_get_ecc_val(ecc_reg);
ecc_status = (ecc_value >> 24) & 0xFF; //获取最高8bit的状态标记值
/* ECC value valid */
if (ecc_status & 0x40) { //推断这个ecc寄存器的值是否是有效的
for (ecc_byte = 0; ecc_byte < 3; ecc_byte++) {
/* Copy ECC bytes to MTD buffer */
*ecc_code = ecc_value & 0xFF;
ecc_value = ecc_value >> 8;
ecc_code++;
}
} else {
pr_warn("%s status failed
", __func__);
return -1;
}
}
return 0;
}
/**
* onehot - onehot function
* @value: Value to check for onehot
*
* This function checks whether a value is onehot or not.
* onehot is if and only if onebit is set.
*
* Return: 1 if it is onehot else 0
*/
static int onehot(unsigned short value)
{
return (value & (value - 1)) == 0;
}
/**
* pl353_nand_correct_data - ECC correction function
* @mtd: Pointer to the mtd_info structure
* @buf: Pointer to the page data
* @read_ecc: Pointer to the ECC value read from spare data area
* @calc_ecc: Pointer to the calculated ECC value
*
* This function corrects the ECC single bit errors & detects 2-bit errors.
*
* Return: 0 if no ECC errors found
* 1 if single bit error found and corrected.
* -1 if multiple ECC errors found.
*/
static int pl353_nand_correct_data(struct mtd_info *mtd, unsigned char *buf,
unsigned char *read_ecc,
unsigned char *calc_ecc)
{
unsigned char bit_addr;
unsigned int byte_addr;
unsigned short ecc_odd, ecc_even, read_ecc_lower, read_ecc_upper;
unsigned short calc_ecc_lower, calc_ecc_upper;
read_ecc_lower = (read_ecc[0] | (read_ecc[1] << 8)) & 0xfff;
read_ecc_upper = ((read_ecc[1] >> 4) | (read_ecc[2] << 4)) & 0xfff;
calc_ecc_lower = (calc_ecc[0] | (calc_ecc[1] << 8)) & 0xfff;
calc_ecc_upper = ((calc_ecc[1] >> 4) | (calc_ecc[2] << 4)) & 0xfff;
ecc_odd = read_ecc_lower ^ calc_ecc_lower; //异或：不同为1，同样为0
ecc_even = read_ecc_upper ^ calc_ecc_upper;
//假设异或结果都为0，则说明read_ecc和calc_ecc是相等的，没有出错，直接退出
if ((ecc_odd == 0) && (ecc_even == 0))
return 0; /* no error */
if (ecc_odd == (~ecc_even & 0xfff)) {
/* bits [11:3] of error code is byte offset */
byte_addr = (ecc_odd >> 3) & 0x1ff; //第几个字节出错
/* bits [2:0] of error code is bit offset */
bit_addr = ecc_odd & 0x7; //第几个bit出错
/* Toggling error bit */
buf[byte_addr] ^= (1 << bit_addr); //纠正出错的bit位
return 1;
}
if (onehot(ecc_odd | ecc_even) == 1)
return 1; /* one error in parity */
return -1; /* Uncorrectable error */
}
/**
* pl353_nand_read_oob - [REPLACABLE] the most common OOB data read function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @page: Page number to read
*
* Return: Always return zero
*/
//将page中的OOB数据读入chip->oob_poi中
static int pl353_nand_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
int page)
{
unsigned long data_phase_addr;
uint8_t *p;
//发送读取OOB数据的命令
chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
p = chip->oob_poi;
chip->read_buf(mtd, p,
(mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH));
p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
//在读取最后4个字节数据时。须要将data_phase_addr的clear_cs位置1，
//通知控制器这是最后的数据读取
data_phase_addr = (unsigned long __force)chip->IO_ADDR_R;
data_phase_addr |= PL353_NAND_CLEAR_CS;
chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
chip->read_buf(mtd, p, PL353_NAND_LAST_TRANSFER_LENGTH);
return 0;
}
/**
* pl353_nand_write_oob - [REPLACABLE] the most common OOB data write function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @page: Page number to write
*
* Return: Zero on success and EIO on failure
*/
static int pl353_nand_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
int page)
{
int status = 0;
const uint8_t *buf = chip->oob_poi;
unsigned long data_phase_addr;
//发送写命令
chip->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize, page);
chip->write_buf(mtd, buf,
(mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH));
buf += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
//在写最后4B数据时，须要设置end command valid。这样在写全然部的数据后，
//写命令的第2个命令NAND_CMD_PAGEPROG才会有效，将数据真正地写入相应的OOB中。
data_phase_addr = (unsigned long __force)chip->IO_ADDR_W;
data_phase_addr |= PL353_NAND_CLEAR_CS; //设置clear cs位为1
data_phase_addr |= (1 << END_CMD_VALID_SHIFT); //设置end command valid
chip->IO_ADDR_W = (void __iomem * __force)data_phase_addr;
chip->write_buf(mtd, buf, PL353_NAND_LAST_TRANSFER_LENGTH);
/* Send command to program the OOB data */
//这条代码不须要，由于NAND_CMD_PAGEPROG已经在data_phase_addr中了
chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
status = chip->waitfunc(mtd, chip);
return status & NAND_STATUS_FAIL ? -EIO : 0;
}
/**
* pl353_nand_read_page_raw - [Intern] read raw page data without ecc
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @buf: Pointer to the data buffer
* @oob_required: Caller requires OOB data read to chip->oob_poi
* @page: Page number to read
*
* Return: Always return zero
*/
//将一个页中的数据读入buf中，将OOB数据读入chip->oob_poi中
static int pl353_nand_read_page_raw(struct mtd_info *mtd,
struct nand_chip *chip,
uint8_t *buf, int oob_required, int page)
{
unsigned long data_phase_addr;
uint8_t *p;
chip->read_buf(mtd, buf, mtd->writesize);
p = chip->oob_poi;
chip->read_buf(mtd, p,
(mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH));
p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
data_phase_addr = (unsigned long __force)chip->IO_ADDR_R;
data_phase_addr |= PL353_NAND_CLEAR_CS;
chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
chip->read_buf(mtd, p, PL353_NAND_LAST_TRANSFER_LENGTH);
return 0;
}
/**
* pl353_nand_write_page_raw - [Intern] raw page write function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @buf: Pointer to the data buffer
* @oob_required: Caller requires OOB data read to chip->oob_poi
*
* Return: Always return zero
*/
//将buf中一页的数据写入页中。并将chip->oob_poi中的数据写入oob区域
static int pl353_nand_write_page_raw(struct mtd_info *mtd,
struct nand_chip *chip,
const uint8_t *buf, int oob_required)
{
unsigned long data_phase_addr;
uint8_t *p;
chip->write_buf(mtd, buf, mtd->writesize);
p = chip->oob_poi;
chip->write_buf(mtd, p,
(mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH));
p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
data_phase_addr = (unsigned long __force)chip->IO_ADDR_W;
data_phase_addr |= PL353_NAND_CLEAR_CS;
data_phase_addr |= (1 << END_CMD_VALID_SHIFT);
chip->IO_ADDR_W = (void __iomem * __force)data_phase_addr;
chip->write_buf(mtd, p, PL353_NAND_LAST_TRANSFER_LENGTH);
return 0;
}
/**
* nand_write_page_hwecc - Hardware ECC based page write function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @buf: Pointer to the data buffer
* @oob_required: Caller requires OOB data read to chip->oob_poi
*
* This functions writes data and hardware generated ECC values in to the page.
*
* Return: Always return zero
*/
//将buf中一页的数据写入页中，并将硬件生成的ecc值写入oob区域
static int pl353_nand_write_page_hwecc(struct mtd_info *mtd,
struct nand_chip *chip, const uint8_t *buf,
int oob_required)
{
int i, eccsize = chip->ecc.size;//为512，即一次ecc计算能处理多少字节数据
int eccsteps = chip->ecc.steps; //一页数据须要多少次ecc计算，如：2KB页大小，要4次ecc计算
uint8_t *ecc_calc = chip->buffers->ecccalc;
const uint8_t *p = buf; //要写入页的数据
uint32_t *eccpos = chip->ecc.layout->eccpos; //ecc在OOB中存放的位置
unsigned long data_phase_addr;
uint8_t *oob_ptr;
//每次写512B数据，
for ( ; (eccsteps - 1); eccsteps--) {
chip->write_buf(mtd, p, eccsize);
p += eccsize;
}
//在写最后一个512B的最后4B数据是，须要设置ECC_LAST来
//通知硬件ecc模块当前是最后一个訪问
chip->write_buf(mtd, p, (eccsize - PL353_NAND_LAST_TRANSFER_LENGTH));
p += (eccsize - PL353_NAND_LAST_TRANSFER_LENGTH);
/* Set ECC Last bit to 1 */
data_phase_addr = (unsigned long __force)chip->IO_ADDR_W;
data_phase_addr |= PL353_NAND_ECC_LAST;
chip->IO_ADDR_W = (void __iomem * __force)data_phase_addr;
chip->write_buf(mtd, p, PL353_NAND_LAST_TRANSFER_LENGTH);
/* Wait for ECC to be calculated and read the error values */
p = buf;
chip->ecc.calculate(mtd, p, &ecc_calc[0]);//获取刚刚硬件计算的ecc值
for (i = 0; i < chip->ecc.total; i++)
chip->oob_poi[eccpos[i]] = ~(ecc_calc[i]);
/* Clear ECC last bit */
data_phase_addr = (unsigned long __force)chip->IO_ADDR_W;
data_phase_addr &= ~PL353_NAND_ECC_LAST;
chip->IO_ADDR_W = (void __iomem * __force)data_phase_addr;
/* Write the spare area with ECC bytes *///写ecc到OOB区域
oob_ptr = chip->oob_poi;
chip->write_buf(mtd, oob_ptr,
(mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH));
data_phase_addr = (unsigned long __force)chip->IO_ADDR_W;
data_phase_addr |= PL353_NAND_CLEAR_CS;
data_phase_addr |= (1 << END_CMD_VALID_SHIFT);
chip->IO_ADDR_W = (void __iomem * __force)data_phase_addr;
oob_ptr += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
chip->write_buf(mtd, oob_ptr, PL353_NAND_LAST_TRANSFER_LENGTH);
return 0;
}
/**
* pl353_nand_write_page_swecc - [REPLACABLE] software ecc based page write function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @buf: Pointer to the data buffer
* @oob_required: Caller requires OOB data read to chip->oob_poi
*
* Return: Always return zero
*/
static int pl353_nand_write_page_swecc(struct mtd_info *mtd,
struct nand_chip *chip, const uint8_t *buf,
int oob_required)
{
int i, eccsize = chip->ecc.size;
int eccbytes = chip->ecc.bytes;
int eccsteps = chip->ecc.steps;
uint8_t *ecc_calc = chip->buffers->ecccalc;
const uint8_t *p = buf;
uint32_t *eccpos = chip->ecc.layout->eccpos;
/* Software ecc calculation */
for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize)
chip->ecc.calculate(mtd, p, &ecc_calc[i]);
for (i = 0; i < chip->ecc.total; i++)
chip->oob_poi[eccpos[i]] = ecc_calc[i];
chip->ecc.write_page_raw(mtd, chip, buf, 1);
return 0;
}
/**
* pl353_nand_read_page_hwecc - Hardware ECC based page read function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @buf: Pointer to the buffer to store read data
* @oob_required: Caller requires OOB data read to chip->oob_poi
* @page: Page number to read
*
* This functions reads data and checks the data integrity by comparing hardware
* generated ECC values and read ECC values from spare area.
*
* Return: 0 always and updates ECC operation status in to MTD structure
*/
static int pl353_nand_read_page_hwecc(struct mtd_info *mtd,
struct nand_chip *chip,
uint8_t *buf, int oob_required, int page)
{
int i, stat, eccsize = chip->ecc.size;
int eccbytes = chip->ecc.bytes;
int eccsteps = chip->ecc.steps;
uint8_t *p = buf;
uint8_t *ecc_calc = chip->buffers->ecccalc;
uint8_t *ecc_code = chip->buffers->ecccode;
uint32_t *eccpos = chip->ecc.layout->eccpos;
unsigned long data_phase_addr;
uint8_t *oob_ptr;
for ( ; (eccsteps - 1); eccsteps--) {
chip->read_buf(mtd, p, eccsize);
p += eccsize;
}
chip->read_buf(mtd, p, (eccsize - PL353_NAND_LAST_TRANSFER_LENGTH));
p += (eccsize - PL353_NAND_LAST_TRANSFER_LENGTH);
/* Set ECC Last bit to 1 */
data_phase_addr = (unsigned long __force)chip->IO_ADDR_R;
data_phase_addr |= PL353_NAND_ECC_LAST;
chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
chip->read_buf(mtd, p, PL353_NAND_LAST_TRANSFER_LENGTH);
/* Read the calculated ECC value */
p = buf;
chip->ecc.calculate(mtd, p, &ecc_calc[0]);
/* Clear ECC last bit */
data_phase_addr = (unsigned long __force)chip->IO_ADDR_R;
data_phase_addr &= ~PL353_NAND_ECC_LAST;
chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
/* Read the stored ECC value */
oob_ptr = chip->oob_poi;
chip->read_buf(mtd, oob_ptr,
(mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH));
/* de-assert chip select */
data_phase_addr = (unsigned long __force)chip->IO_ADDR_R;
data_phase_addr |= PL353_NAND_CLEAR_CS;
chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
oob_ptr += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
chip->read_buf(mtd, oob_ptr, PL353_NAND_LAST_TRANSFER_LENGTH);
for (i = 0; i < chip->ecc.total; i++)
ecc_code[i] = ~(chip->oob_poi[eccpos[i]]);
eccsteps = chip->ecc.steps;
p = buf;
/* Check ECC error for all blocks and correct if it is correctable */
//使用ecc对读出来的数据进行检查，假设发现错误就尝试纠正
for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
if (stat < 0) //假设返回值为-1。表示发生了不可纠正的错误
mtd->ecc_stats.failed++;
else //返回0或者1。表示没有错误或发生了可纠正的错误
mtd->ecc_stats.corrected += stat;
}
return 0;
}
/**
* pl353_nand_read_page_swecc - [REPLACABLE] software ecc based page read function
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
* @buf: Pointer to the buffer to store read data
* @oob_required: Caller requires OOB data read to chip->oob_poi
* @page: Page number to read
*
* Return: Always return zero
*/
static int pl353_nand_read_page_swecc(struct mtd_info *mtd,
struct nand_chip *chip,
uint8_t *buf, int oob_required, int page)
{
int i, eccsize = chip->ecc.size;
int eccbytes = chip->ecc.bytes;
int eccsteps = chip->ecc.steps;
uint8_t *p = buf;
uint8_t *ecc_calc = chip->buffers->ecccalc;
uint8_t *ecc_code = chip->buffers->ecccode;
uint32_t *eccpos = chip->ecc.layout->eccpos;
chip->ecc.read_page_raw(mtd, chip, buf, page, 1);
for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize)
chip->ecc.calculate(mtd, p, &ecc_calc[i]);
for (i = 0; i < chip->ecc.total; i++)
ecc_code[i] = chip->oob_poi[eccpos[i]];
eccsteps = chip->ecc.steps;
p = buf;
for (i = 0 ; eccsteps; eccsteps--, i += eccbytes, p += eccsize) {
int stat;
stat = chip->ecc.correct(mtd, p, &ecc_code[i], &ecc_calc[i]);
if (stat < 0)
mtd->ecc_stats.failed++;
else
mtd->ecc_stats.corrected += stat;
}
return 0;
}
/**
* pl353_nand_select_chip - Select the flash device
* @mtd: Pointer to the mtd info structure
* @chip: Pointer to the NAND chip info structure
*
* This function is empty as the NAND controller handles chip select line
* internally based on the chip address passed in command and data phase.
*/
static void pl353_nand_select_chip(struct mtd_info *mtd, int chip)
{
return;
}
/**
* pl353_nand_cmd_function - Send command to NAND device
* @mtd: Pointer to the mtd_info structure
* @command: The command to be sent to the flash device
* @column: The column address for this command, -1 if none
* @page_addr: The page address for this command, -1 if none
*/
static void pl353_nand_cmd_function(struct mtd_info *mtd, unsigned int command,
int column, int page_addr)
{
struct nand_chip *chip = mtd->priv;
const struct pl353_nand_command_format *curr_cmd = NULL;
struct pl353_nand_info *xnand =
container_of(mtd, struct pl353_nand_info, mtd);
void __iomem *cmd_addr;
unsigned long cmd_data = 0, end_cmd_valid = 0;
unsigned long cmd_phase_addr, data_phase_addr, end_cmd, i;
unsigned long timeout = jiffies + PL353_NAND_DEV_BUSY_TIMEOUT;
if (xnand->end_cmd_pending) {//假设end_cmd_pending为1，表示前一次调用这个函数的命令有end command
/*
* Check for end command if this command request is same as the
* pending command then return
*/
if (xnand->end_cmd == command) {
xnand->end_cmd = 0;
xnand->end_cmd_pending = 0;
return;
}
}
/* Emulate NAND_CMD_READOOB for large page device */
if ((mtd->writesize > PL353_NAND_ECC_SIZE) &&
(command == NAND_CMD_READOOB)) {
column += mtd->writesize;
command = NAND_CMD_READ0;
}
/* Get the command format */
for (i = 0; (pl353_nand_commands[i].start_cmd != NAND_CMD_NONE ||
pl353_nand_commands[i].end_cmd != NAND_CMD_NONE); i++)
if (command == pl353_nand_commands[i].start_cmd)
curr_cmd = &pl353_nand_commands[i];
if (curr_cmd == NULL)//假设为空，表示当前命令是无效的，退出
return;
/* Clear interrupt */
pl353_smc_clr_nand_int();
/* Get the command phase address */
if (curr_cmd->end_cmd_valid == PL353_NAND_CMD_PHASE)
end_cmd_valid = 1;
if (curr_cmd->end_cmd == NAND_CMD_NONE)
end_cmd = 0x0;
else
end_cmd = curr_cmd->end_cmd;
//cmd_phase_addr和data_phase_addr的意义须要看pl353数据手冊
//在pl353中命令參数是包括在命令阶段地址和数据阶段地址中的
cmd_phase_addr = (unsigned long __force)xnand->nand_base |
(curr_cmd->addr_cycles << ADDR_CYCLES_SHIFT) | //地址周期的个数
(end_cmd_valid << END_CMD_VALID_SHIFT) |
(COMMAND_PHASE) | //为0，表示这是命令阶段地址
(end_cmd << END_CMD_SHIFT) |
(curr_cmd->start_cmd << START_CMD_SHIFT);
cmd_addr = (void __iomem * __force)cmd_phase_addr;
/* Get the data phase address */
end_cmd_valid = 0;
data_phase_addr = (unsigned long __force)xnand->nand_base |
(0x0 << CLEAR_CS_SHIFT) |
(end_cmd_valid << END_CMD_VALID_SHIFT) |
(DATA_PHASE) | //为1。表示这个数据阶段地址
(end_cmd << END_CMD_SHIFT) |
(0x0 << ECC_LAST_SHIFT);
chip->IO_ADDR_R = (void __iomem * __force)data_phase_addr;
chip->IO_ADDR_W = chip->IO_ADDR_R;
/* Command phase AXI write */
/* Read & Write */
//依据column和page_addr等參数，生成要发送的地址cmd_data
if (column != -1 && page_addr != -1) {
/* Adjust columns for 16 bit bus width */
if (chip->options & NAND_BUSWIDTH_16)
column >>= 1;
cmd_data = column;
if (mtd->writesize > PL353_NAND_ECC_SIZE) {
cmd_data |= page_addr << 16;
/* Another address cycle for devices > 128MiB */
if (chip->chipsize > (128 << 20)) {
pl353_nand_write32(cmd_addr, cmd_data);//假设是大页，在这里先发送前4个周期的地址
cmd_data = (page_addr >> 16);
}
} else {
cmd_data |= page_addr << 8;
}
} else if (page_addr != -1) {
/* Erase */
cmd_data = page_addr;
} else if (column != -1) {
/*
* Change read/write column, read id etc
* Adjust columns for 16 bit bus width
*/
if ((chip->options & NAND_BUSWIDTH_16) &&
((command == NAND_CMD_READ0) ||
(command == NAND_CMD_SEQIN) ||
(command == NAND_CMD_RNDOUT) ||
(command == NAND_CMD_RNDIN)))
column >>= 1;
cmd_data = column;
}
//发送小页的4个周期地址或者大页的第5个周期地址
pl353_nand_write32(cmd_addr, cmd_data);
//假设当前命令有end command，则将xnand->end_cmd_pending置1
if (curr_cmd->end_cmd_valid) {
xnand->end_cmd = curr_cmd->end_cmd;
xnand->end_cmd_pending = 1;
}
//延时。等待命令完毕
ndelay(100);
if ((command == NAND_CMD_READ0) ||
(command == NAND_CMD_RESET) ||
(command == NAND_CMD_PARAM) ||
(command == NAND_CMD_GET_FEATURES)) {
/* Wait till the device is ready or timeout */
do {
if (chip->dev_ready(mtd))
break;
else
cpu_relax();
} while (!time_after_eq(jiffies, timeout));
if (time_after_eq(jiffies, timeout))
pr_err("%s timed out
", __func__);
return;
}
}
/**
* pl353_nand_read_buf - read chip data into buffer
* @mtd: Pointer to the mtd info structure
* @buf: Pointer to the buffer to store read data
* @len: Number of bytes to read
*/
static void pl353_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
{
int i;
struct nand_chip *chip = mtd->priv;
unsigned long *ptr = (unsigned long *)buf;
len >>= 2;
for (i = 0; i < len; i++)
ptr[i] = readl(chip->IO_ADDR_R);//通过IO_ADDR_R地址读取数据
}
/**
* pl353_nand_write_buf - write buffer to chip
* @mtd: Pointer to the mtd info structure
* @buf: Pointer to the buffer to store read data
* @len: Number of bytes to write
*/
static void pl353_nand_write_buf(struct mtd_info *mtd, const uint8_t *buf,
int len)
{
int i;
struct nand_chip *chip = mtd->priv;
unsigned long *ptr = (unsigned long *)buf;
len >>= 2;
for (i = 0; i < len; i++)
writel(ptr[i], chip->IO_ADDR_W);
}
/**
* pl353_nand_device_ready - Check device ready/busy line
* @mtd: Pointer to the mtd_info structure
*
* Return: 0 on busy or 1 on ready state
*/
//查询设备是否处于空暇状态
static int pl353_nand_device_ready(struct mtd_info *mtd)
{
if (pl353_smc_get_nand_int_status_raw()) {
pl353_smc_clr_nand_int();
return 1;
}
return 0;
}
/**
* pl353_nand_detect_ondie_ecc - Get the flash ondie ecc state
* @mtd: Pointer to the mtd_info structure
*
* This function enables the ondie ecc for the Micron ondie ecc capable devices
*
* Return: 1 on detect, 0 if fail to detect
*/
static int pl353_nand_detect_ondie_ecc(struct mtd_info *mtd)
{
struct nand_chip *nand_chip = mtd->priv;
u8 maf_id, dev_id, i, get_feature;
u8 set_feature[4] = { 0x08, 0x00, 0x00, 0x00 };
/* Check if On-Die ECC flash */
nand_chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
//发送ReadID的命令：0x90去取得nand 芯片的ID信息
nand_chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
/* Read manufacturer and device IDs */
maf_id = readb(nand_chip->IO_ADDR_R);//第一个字节是厂商ID
dev_id = readb(nand_chip->IO_ADDR_R);//第二个字节是芯片ID
if ((maf_id == NAND_MFR_MICRON) &&
((dev_id == 0xf1) || (dev_id == 0xa1) ||
(dev_id == 0xb1) || (dev_id == 0xaa) ||
(dev_id == 0xba) || (dev_id == 0xda) ||
(dev_id == 0xca) || (dev_id == 0xac) ||
(dev_id == 0xbc) || (dev_id == 0xdc) ||
(dev_id == 0xcc) || (dev_id == 0xa3) ||
(dev_id == 0xb3) ||
(dev_id == 0xd3) || (dev_id == 0xc3))) {
nand_chip->cmdfunc(mtd, NAND_CMD_GET_FEATURES,
ONDIE_ECC_FEATURE_ADDR, -1);
get_feature = readb(nand_chip->IO_ADDR_R);
if (get_feature & 0x08) {
return 1;
} else {
nand_chip->cmdfunc(mtd, NAND_CMD_SET_FEATURES,
ONDIE_ECC_FEATURE_ADDR, -1);
for (i = 0; i < 4; i++)
writeb(set_feature[i], nand_chip->IO_ADDR_W);
ndelay(1000);
nand_chip->cmdfunc(mtd, NAND_CMD_GET_FEATURES,
ONDIE_ECC_FEATURE_ADDR, -1);
get_feature = readb(nand_chip->IO_ADDR_R);
if (get_feature & 0x08)
return 1;
}
}
return 0;
}
/**
* pl353_nand_ecc_init - Initialize the ecc information as per the ecc mode
* @mtd: Pointer to the mtd_info structure
* @ondie_ecc_state: ondie ecc status
*
* This function initializes the ecc block and functional pointers as per the
* ecc mode
*/
static void pl353_nand_ecc_init(struct mtd_info *mtd, int ondie_ecc_state)
{
struct nand_chip *nand_chip = mtd->priv;
nand_chip->ecc.mode = NAND_ECC_HW;//使用硬件ecc
nand_chip->ecc.read_oob = pl353_nand_read_oob;
nand_chip->ecc.read_page_raw = pl353_nand_read_page_raw;
nand_chip->ecc.strength = 1;
nand_chip->ecc.write_oob = pl353_nand_write_oob;
nand_chip->ecc.write_page_raw = pl353_nand_write_page_raw;
if (ondie_ecc_state) {
/* bypass the controller ECC block */
pl353_smc_set_ecc_mode(PL353_SMC_ECCMODE_BYPASS);
/*
* The software ECC routines won't work with the
* SMC controller
*/
nand_chip->ecc.bytes = 0;
nand_chip->ecc.layout = &ondie_nand_oob_64;
nand_chip->ecc.read_page = pl353_nand_read_page_raw;
nand_chip->ecc.write_page = pl353_nand_write_page_raw;
nand_chip->ecc.size = mtd->writesize;
/*
* On-Die ECC spare bytes offset 8 is used for ECC codes
* Use the BBT pattern descriptors
*/
nand_chip->bbt_td = &bbt_main_descr;
nand_chip->bbt_md = &bbt_mirror_descr;
} else {
/* Hardware ECC generates 3 bytes ECC code for each 512 bytes */
nand_chip->ecc.bytes = 3;
nand_chip->ecc.calculate = pl353_nand_calculate_hwecc;
nand_chip->ecc.correct = pl353_nand_correct_data;
nand_chip->ecc.hwctl = NULL;
nand_chip->ecc.read_page = pl353_nand_read_page_hwecc;
nand_chip->ecc.size = PL353_NAND_ECC_SIZE;
nand_chip->ecc.write_page = pl353_nand_write_page_hwecc;
pl353_smc_set_ecc_pg_size(mtd->writesize);
switch (mtd->writesize) {
case 512:
case 1024:
case 2048:
pl353_smc_set_ecc_mode(PL353_SMC_ECCMODE_APB);
break;
default:
/*
* The software ECC routines won't work with the
* SMC controller
*/
nand_chip->ecc.calculate = nand_calculate_ecc;
nand_chip->ecc.correct = nand_correct_data;
nand_chip->ecc.read_page = pl353_nand_read_page_swecc;
nand_chip->ecc.write_page = pl353_nand_write_page_swecc;
nand_chip->ecc.size = 256;
break;
}
//假设这里没有设置layout的值。将会在nand_scan_tail中再次依据oobsize的
//值来设置一个默认的layout
if (mtd->oobsize == 16) //一般页中每512字节会分配16字节的OOB空间
nand_chip->ecc.layout = &nand_oob_16;
else if (mtd->oobsize == 64)
nand_chip->ecc.layout = &nand_oob_64;
}
}
/**
* pl353_nand_probe - Probe method for the NAND driver
* @pdev: Pointer to the platform_device structure
*
* This function initializes the driver data structures and the hardware.
*
* Return: 0 on success or error value on failure
*/
static int pl353_nand_probe(struct platform_device *pdev)
{
struct pl353_nand_info *xnand;
struct mtd_info *mtd;
struct nand_chip *nand_chip;
struct resource *res;
struct mtd_part_parser_data ppdata;
int ondie_ecc_state;
xnand = devm_kzalloc(&pdev->dev, sizeof(*xnand), GFP_KERNEL);
if (!xnand)
return -ENOMEM;
/* Map physical address of NAND flash */
//映射nand flash的基地值，这个值在pl353数据手冊中设定
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
xnand->nand_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(xnand->nand_base))
return PTR_ERR(xnand->nand_base);
/* Link the private data with the MTD structure */
mtd = &xnand->mtd;
nand_chip = &xnand->chip;
nand_chip->priv = xnand;
mtd->priv = nand_chip;
mtd->owner = THIS_MODULE;
mtd->name = PL353_NAND_DRIVER_NAME;
/* Set address of NAND IO lines */
nand_chip->IO_ADDR_R = xnand->nand_base;
nand_chip->IO_ADDR_W = xnand->nand_base;
//假设nand_chip的一些函数没有在这里实现，则会在nand_base.c文件的
//nand_set_defaults函数中将他们设置为nand_base.c中通用的函数
/* Set the driver entry points for MTD */
nand_chip->cmdfunc = pl353_nand_cmd_function;
nand_chip->dev_ready = pl353_nand_device_ready;
nand_chip->select_chip = pl353_nand_select_chip;
/* If we don't set this delay driver sets 20us by default */
nand_chip->chip_delay = 30;
/* Buffer read/write routines */
nand_chip->read_buf = pl353_nand_read_buf;
nand_chip->write_buf = pl353_nand_write_buf;
/* Set the device option and flash width */
nand_chip->options = NAND_BUSWIDTH_AUTO;//依据硬件，自己主动设置nand总线宽度
nand_chip->bbt_options = NAND_BBT_USE_FLASH;//bbt存放在nand中
platform_set_drvdata(pdev, xnand);
ondie_ecc_state = pl353_nand_detect_ondie_ecc(mtd);
/* first scan to find the device and get the page size */
if (nand_scan_ident(mtd, 1, NULL)) {
dev_err(&pdev->dev, "nand_scan_ident for NAND failed
");
return -ENXIO;
}
pl353_nand_ecc_init(mtd, ondie_ecc_state);
if (nand_chip->options & NAND_BUSWIDTH_16)
pl353_smc_set_buswidth(PL353_SMC_MEM_WIDTH_16);
/* second phase scan */
//在nand_scan_tail函数功能：对nand_chip->ecc和mtd余下部分赋值，建立坏块表等
if (nand_scan_tail(mtd)) {
dev_err(&pdev->dev, "nand_scan_tail for NAND failed
");
return -ENXIO;
}
ppdata.of_node = pdev->dev.of_node;
mtd_device_parse_register(&xnand->mtd, NULL, &ppdata, NULL, 0);
return 0;
}
/**
* pl353_nand_remove - Remove method for the NAND driver
* @pdev: Pointer to the platform_device structure
*
* This function is called if the driver module is being unloaded. It frees all
* resources allocated to the device.
*
* Return: 0 on success or error value on failure
*/
static int pl353_nand_remove(struct platform_device *pdev)
{
struct pl353_nand_info *xnand = platform_get_drvdata(pdev);
/* Release resources, unregister device */
nand_release(&xnand->mtd);
/* kfree(NULL) is safe */
kfree(xnand->parts);
return 0;
}
/* Match table for device tree binding */
static const struct of_device_id pl353_nand_of_match[] = {
{ .compatible = "arm,pl353-nand-r2p1" },
{},
};
MODULE_DEVICE_TABLE(of, pl353_nand_of_match);
/*
* pl353_nand_driver - This structure defines the NAND subsystem platform driver
*/
static struct platform_driver pl353_nand_driver = {
.probe = pl353_nand_probe,
.remove = pl353_nand_remove,
.driver = {
.name = PL353_NAND_DRIVER_NAME,
.owner = THIS_MODULE,
.of_match_table = pl353_nand_of_match,
},
};
module_platform_driver(pl353_nand_driver);
MODULE_AUTHOR("Xilinx, Inc.");
MODULE_ALIAS("platform:" PL353_NAND_DRIVER_NAME);
MODULE_DESCRIPTION("ARM PL353 NAND Flash Driver");
MODULE_LICENSE("GPL");
//在nand_scan_ident函数中会调用nand_get_flash_type函数。这个函数非常重要。主要是获取
//nand flash一些基本參数。如页大小，块大小等。
/*
* Get the flash and manufacturer id and lookup if the type is supported.
*/
static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
struct nand_chip *chip,
int *maf_id, int *dev_id,
struct nand_flash_dev *type)
{
int busw;//硬件的总线宽度
int i, maf_idx;
u8 id_data[8];
/* Select the device */
chip->select_chip(mtd, 0);//选中芯片，才干对其操作
/*
* Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx)
* after power-up.
*/
chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
/* Send the command for reading device ID */
chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
/* Read manufacturer and device IDs */
*maf_id = chip->read_byte(mtd);
*dev_id = chip->read_byte(mtd);
/*
* Try again to make sure, as some systems the bus-hold or other
* interface concerns can cause random data which looks like a
* possibly credible NAND flash to appear. If the two results do
* not match, ignore the device completely.
*/
chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
//获取整个ID数据，总共同拥有8字节
/* Read entire ID string */
for (i = 0; i < 8; i++)
id_data[i] = chip->read_byte(mtd);
//推断第二次读取的ID是否与第一次读取的一样，不一样则说明设备有问题
if (id_data[0] != *maf_id || id_data[1] != *dev_id) {
pr_info("second ID read did not match %02x,%02x against %02x,%02x
",
*maf_id, *dev_id, id_data[0], id_data[1]);
return ERR_PTR(-ENODEV);
}
if (!type)
type = nand_flash_ids;
for (; type->name != NULL; type++) {
if (is_full_id_nand(type)) {
if (find_full_id_nand(mtd, chip, type, id_data, &busw))
goto ident_done;
} else if (*dev_id == type->dev_id) {//找到这个芯片ID相应的nand_flash_dev
break;
}
}
chip->onfi_version = 0;
if (!type->name || !type->pagesize) {
/* Check if the chip is ONFI compliant */
if (nand_flash_detect_onfi(mtd, chip, &busw))
goto ident_done;
/* Check if the chip is JEDEC compliant */
if (nand_flash_detect_jedec(mtd, chip, &busw))
goto ident_done;
}
//name为空，表示没有在nand_flash_ids数组中找到此芯片ID相应的设备
if (!type->name)
return ERR_PTR(-ENODEV);
if (!mtd->name)
mtd->name = type->name;
chip->chipsize = (uint64_t)type->chipsize << 20;
if (!type->pagesize && chip->init_size) {
/* Set the pagesize, oobsize, erasesize by the driver */
busw = chip->init_size(mtd, chip, id_data);
} else if (!type->pagesize) {
/* Decode parameters from extended ID */
nand_decode_ext_id(mtd, chip, id_data, &busw);
} else {
//假设type->pagesize不为0。则使用type的參数来设置
//mtd中芯片writesize,oobsize,erasesize的值
nand_decode_id(mtd, chip, type, id_data, &busw);
}
/* Get chip options */
chip->options |= type->options;
/*
* Check if chip is not a Samsung device. Do not clear the
* options for chips which do not have an extended id.
*/
if (*maf_id != NAND_MFR_SAMSUNG && !type->pagesize)
chip->options &= ~NAND_SAMSUNG_LP_OPTIONS;
ident_done:
/* Try to identify manufacturer */
for (maf_idx = 0; nand_manuf_ids[maf_idx].id != 0x0; maf_idx++) {
if (nand_manuf_ids[maf_idx].id == *maf_id)
break;
}
if (chip->options & NAND_BUSWIDTH_AUTO) {//依据硬件。自己主动设在总线宽度
WARN_ON(chip->options & NAND_BUSWIDTH_16);
chip->options |= busw;
nand_set_defaults(chip, busw);
} else if (busw != (chip->options & NAND_BUSWIDTH_16)) {
//否则检測驱动中关于位宽的定义是否和硬件一致
/*
* Check, if buswidth is correct. Hardware drivers should set
* chip correct!
*/
pr_info("device found, Manufacturer ID: 0x%02x, Chip ID: 0x%02x
",
*maf_id, *dev_id);
pr_info("%s %s
", nand_manuf_ids[maf_idx].name, mtd->name);
pr_warn("bus width %d instead %d bit
",
(chip->options & NAND_BUSWIDTH_16) ? 16 : 8,
busw ? 16 : 8);
return ERR_PTR(-EINVAL);
}
nand_decode_bbm_options(mtd, chip, id_data);
/* Calculate the address shift from the page size */
chip->page_shift = ffs(mtd->writesize) - 1;
/* Convert chipsize to number of pages per chip -1 */
chip->pagemask = (chip->chipsize >> chip->page_shift) - 1;
chip->bbt_erase_shift = chip->phys_erase_shift =
ffs(mtd->erasesize) - 1;
if (chip->chipsize & 0xffffffff)//推断是否超过4GB，预计是ffs函数最多支持32位
chip->chip_shift = ffs((unsigned)chip->chipsize) - 1;
else {
chip->chip_shift = ffs((unsigned)(chip->chipsize >> 32));
chip->chip_shift += 32 - 1;
}
chip->badblockbits = 8;
chip->erase = single_erase;
/* Do not replace user supplied command function! */
if (mtd->writesize > 512 && chip->cmdfunc == nand_command)
chip->cmdfunc = nand_command_lp;//大页使用的默认命令函数
pr_info("device found, Manufacturer ID: 0x%02x, Chip ID: 0x%02x
",
*maf_id, *dev_id);
if (chip->onfi_version)
pr_info("%s %s
", nand_manuf_ids[maf_idx].name,
chip->onfi_params.model);
else if (chip->jedec_version)
pr_info("%s %s
", nand_manuf_ids[maf_idx].name,
chip->jedec_params.model);
else
pr_info("%s %s
", nand_manuf_ids[maf_idx].name,
type->name);
pr_info("%dMiB, %s, page size: %d, OOB size: %d
",
(int)(chip->chipsize >> 20), nand_is_slc(chip) ?
"SLC" : "MLC",
mtd->writesize, mtd->oobsize);
return type;
}