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ARM·Nand Flash的控制

作者：時(shí)間：2016-11-24 來(lái)源：網(wǎng)絡(luò)

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【本章總結(jié)】

個(gè)人覺(jué)得這章內(nèi)容過(guò)于復(fù)雜，只需要記住如果nand中4096的程序想要被拷貝出來(lái)執(zhí)行，就把這個(gè)代碼寫進(jìn)去，紅色部分是真正的代碼，可以復(fù)制過(guò)去，直接使用，其他就不做了解了。聽(tīng)了一個(gè)小時(shí)，這個(gè)老師講的也挺亂的，也沒(méi)有人能記住這么多東西吧。。。

【head.S init.c main.c nand.c Makefile】

代碼詳解，這里先把一部分代碼存放在NAND Flash 地址4096之后，當(dāng)程序啟動(dòng)后通過(guò)NAND Flash控制器將他們讀出來(lái)、執(zhí)行。

注意：以前的代碼都小于4096，開(kāi)發(fā)板啟動(dòng)后他們被自動(dòng)復(fù)制進(jìn)“Steppingstone”；

現(xiàn)在的代碼在4096之后，需要控制NAND Flash將他們讀出來(lái)、執(zhí)行

【nand.lds】

SECTIONS {

firtst 0x00000000 : { head.o init.o nand.o}

second 0x30000000 : AT(4096) { main.o }

}

對(duì)于這里，我是這樣理解的。head.o init.o nand.o都放在Nand flash0地址處，0x0000 0000是他的鏈接地址，也就是放在0x0000 0000處運(yùn)行；mian.o存放在Nand flash 4096地址處，0x3000 0000是他的鏈接地址，也就是放在0x3000 0000處運(yùn)行

（可能也就是前一陣子看到的鏈接地址和加載地址的區(qū)別）

當(dāng)開(kāi)發(fā)板啟動(dòng)時(shí)，前4k的代碼被考進(jìn)SRAM，所以我們需要在SRAM內(nèi)完成初始化和跳轉(zhuǎn)

【head.s】

SECTIONS {

firtst 0x00000000 : { head.o init.o nand.o}

second 0x30000000 : AT(4096) { main.o }

} @******************************************************************************

@ File：head.s

@ 功能：設(shè)置SDRAM，將程序復(fù)制到SDRAM，然后跳到SDRAM繼續(xù)執(zhí)行

@******************************************************************************

.text

.global _start

_start:

@函數(shù)disable_watch_dog, memsetup, init_nand, nand_read_ll在init.c中定義

ldr sp, =4096 @設(shè)置堆棧

bl disable_watch_dog @關(guān)WATCH DOG

bl memsetup @初始化SDRAM

bl nand_init @初始化NAND Flash

@將NAND Flash中地址4096開(kāi)始的1024字節(jié)代碼(main.c編譯得到)復(fù)制到SDRAM中

@nand_read_ll函數(shù)需要3個(gè)參數(shù)：

ldr r0, =0x30000000 @1. 目標(biāo)地址=0x30000000，這是SDRAM的起始地址

mov r1, #4096 @2. 源地址 = 4096，連接的時(shí)候，main.c中的代碼都存在NAND Flash地址4096開(kāi)始處

mov r2, #2048 @3. 復(fù)制長(zhǎng)度= 2048(bytes)，對(duì)于本實(shí)驗(yàn)的main.c，這是足夠了

bl nand_read @調(diào)用C函數(shù)nand_read

ldr sp, =0x34000000 @設(shè)置棧

ldr lr, =halt_loop @設(shè)置返回地址

ldr pc, =main @b指令和bl指令只能前后跳轉(zhuǎn)32M的范圍，所以這里使用向pc賦值的方法進(jìn)行跳轉(zhuǎn)

halt_loop:

b halt_loop

*對(duì)于這一串代碼，很多都是前面學(xué)過(guò)的知識(shí)，這里我們只關(guān)注配置Nand的紅色代碼

bl nand_init

*目標(biāo)地址，源地址，目標(biāo)長(zhǎng)度

ldr r0, =0x30000000 @1. 目標(biāo)地址=0x30000000，這是SDRAM的起始地址

mov r1, #4096 @2. 源地址 = 4096，連接的時(shí)候，main.c中的代碼都存在NAND Flash地址4096開(kāi)始處

mov r2, #2048 @3. 復(fù)制長(zhǎng)度= 2048(bytes)，對(duì)于本實(shí)驗(yàn)的main.c，這是足夠了

bl nand_read @調(diào)用C函數(shù)nand_read

這里我們可以跳轉(zhuǎn)到nand_read中可以看一下

void nand_read(unsigned char *buf, unsigned long start_addr, int size)

{

int i, j;

#ifdef LARGER_NAND_PAGE

if ((start_addr & NAND_BLOCK_MASK_LP) || (size & NAND_BLOCK_MASK_LP)) {

return ;

}

#else

if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK)) {

return ;

}

#endif

nand_select_chip();

for(i=start_addr; i < (start_addr + size);) {

write_cmd(0);

write_addr(i);

#ifdef LARGER_NAND_PAGE

write_cmd(0x30);

#endif

wait_idle();

#ifdef LARGER_NAND_PAGE

for(j=0; j < NAND_SECTOR_SIZE_LP; j++, i++) {

#else

for(j=0; j < NAND_SECTOR_SIZE; j++, i++) {

#endif

*buf = read_data();

buf++;

}

【nand.c】

#define LARGER_NAND_PAGE

#define GSTATUS1 (*(volatile unsigned int *)0x560000B0)

#define BUSY 1

#define NAND_SECTOR_SIZE 512

#define NAND_BLOCK_MASK (NAND_SECTOR_SIZE - 1)

#define NAND_SECTOR_SIZE_LP 2048

#define NAND_BLOCK_MASK_LP (NAND_SECTOR_SIZE_LP - 1)

typedef unsigned int S3C24X0_REG32;

typedef struct {

S3C24X0_REG32 NFCONF;

S3C24X0_REG32 NFCMD;

S3C24X0_REG32 NFADDR;

S3C24X0_REG32 NFDATA;

S3C24X0_REG32 NFSTAT;

S3C24X0_REG32 NFECC;

} S3C2410_NAND;

typedef struct {

S3C24X0_REG32 NFCONF;

S3C24X0_REG32 NFCONT;

S3C24X0_REG32 NFCMD;

S3C24X0_REG32 NFADDR;

S3C24X0_REG32 NFDATA;

S3C24X0_REG32 NFMECCD0;

S3C24X0_REG32 NFMECCD1;

S3C24X0_REG32 NFSECCD;

S3C24X0_REG32 NFSTAT;

S3C24X0_REG32 NFESTAT0;

S3C24X0_REG32 NFESTAT1;

S3C24X0_REG32 NFMECC0;

S3C24X0_REG32 NFMECC1;

S3C24X0_REG32 NFSECC;

S3C24X0_REG32 NFSBLK;

S3C24X0_REG32 NFEBLK;

} S3C2440_NAND;

typedef struct {

void (*nand_reset)(void);

void (*wait_idle)(void);

void (*nand_select_chip)(void);

void (*nand_deselect_chip)(void);

void (*write_cmd)(int cmd);

void (*write_addr)(unsigned int addr);

unsigned char (*read_data)(void);

}t_nand_chip;

static S3C2410_NAND * s3c2410nand = (S3C2410_NAND *)0x4e000000;

static S3C2440_NAND * s3c2440nand = (S3C2440_NAND *)0x4e000000;

static t_nand_chip nand_chip;

void nand_init(void);

void nand_read(unsigned char *buf, unsigned long start_addr, int size);

static void nand_reset(void);

static void wait_idle(void);

static void nand_select_chip(void);

static void nand_deselect_chip(void);

static void write_cmd(int cmd);

static void write_addr(unsigned int addr);

static unsigned char read_data(void);

static void s3c2410_nand_reset(void);

static void s3c2410_wait_idle(void);

static void s3c2410_nand_select_chip(void);

static void s3c2410_nand_deselect_chip(void);

static void s3c2410_write_cmd(int cmd);

static void s3c2410_write_addr(unsigned int addr);

static unsigned char s3c2410_read_data();

static void s3c2440_nand_reset(void);

static void s3c2440_wait_idle(void);

static void s3c2440_nand_select_chip(void);

static void s3c2440_nand_deselect_chip(void);

static void s3c2440_write_cmd(int cmd);

static void s3c2440_write_addr(unsigned int addr);

static unsigned char s3c2440_read_data(void);

static void s3c2410_nand_reset(void)

{

s3c2410_nand_select_chip();

s3c2410_write_cmd(0xff); // 復(fù)位命令

s3c2410_wait_idle();

s3c2410_nand_deselect_chip();

}

static void s3c2410_wait_idle(void)

{

int i;

volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFSTAT;

while(!(*p & BUSY))

for(i=0; i<10; i++);

}

static void s3c2410_nand_select_chip(void)

{

int i;

s3c2410nand->NFCONF &= ~(1<<11);

for(i=0; i<10; i++);

}

static void s3c2410_nand_deselect_chip(void)

{

s3c2410nand->NFCONF |= (1<<11);

}

static void s3c2410_write_cmd(int cmd)

{

volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFCMD;

*p = cmd;

}

static void s3c2410_write_addr(unsigned int addr)

{

int i;

volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFADDR;

*p = addr & 0xff;

for(i=0; i<10; i++);

*p = (addr >> 9) & 0xff;

for(i=0; i<10; i++);

*p = (addr >> 17) & 0xff;

for(i=0; i<10; i++);

*p = (addr >> 25) & 0xff;

for(i=0; i<10; i++);

}

static unsigned char s3c2410_read_data(void)

{

volatile unsigned char *p = (volatile unsigned char *)&s3c2410nand->NFDATA;

return *p;

}

static void s3c2440_nand_reset(void)

{

s3c2440_nand_select_chip();

s3c2440_write_cmd(0xff); // 復(fù)位命令

s3c2440_wait_idle();

s3c2440_nand_deselect_chip();

}

static void s3c2440_wait_idle(void)

{

int i;

volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFSTAT;

while(!(*p & BUSY))

for(i=0; i<10; i++);

}

static void s3c2440_nand_select_chip(void)

{

int i;

s3c2440nand->NFCONT &= ~(1<<1);

for(i=0; i<10; i++);

}

static void s3c2440_nand_deselect_chip(void)

{

s3c2440nand->NFCONT |= (1<<1);

}

static void s3c2440_write_cmd(int cmd)

{

volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFCMD;

*p = cmd;

}

static void s3c2440_write_addr(unsigned int addr)

{

int i;

volatile unsigned char *p = (volatile unsigned char *)&s3c2440nand->NFADDR;

*p = addr & 0xff;

for(i=0; i<10; i++);

*p = (addr >> 9) & 0xff;

for(i=0; i<10; i++);

*p = (addr >> 17) & 0xff;

for(i=0; i<10; i++);

*p = (addr >> 25) & 0xff;

for(i=0; i<10; i++);

}

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