U-BOOT/Board/flash.c 分析

#include <common.h>
ulong myflush (void);
//请仔细阅读Am29LV400手册
//PHYS_FLASH_SIZE=512KB 定义咋include/configs/embendsky.h中
#define FLASH_BANK_SIZE PHYS_FLASH_SIZE
//根据Am29LV400手册可知 有11个sect。最大sect的大小为64KB
#define MAIN_SECT_SIZE 0x10000 /* 64 KB */
//CFG_MAX_FLASH_BANKS=1 定义咋include/configs/embendsky.h中
flash_info_t flash_info[CFG_MAX_FLASH_BANKS];
//一下所有命令字节的定义 都可以从Am29LV400手册中获得
#define CMD_READ_ARRAY 0x000000F0
#define CMD_UNLOCK1 0x000000AA
#define CMD_UNLOCK2 0x00000055
#define CMD_ERASE_SETUP 0x00000080
#define CMD_ERASE_CONFIRM 0x00000030
#define CMD_PROGRAM 0x000000A0
#define CMD_UNLOCK_BYPASS 0x00000020
//#define PHYS_FLASH_1 0x00000000 /* Flash Bank #1 */
//#define CFG_FLASH_BASE PHYS_FLASH_1 定义在include/configs/embendsky.h中
#define MEM_FLASH_ADDR1 (*(volatile u16 *)(CFG_FLASH_BASE + (0x00000555 << 1)))
#define MEM_FLASH_ADDR2 (*(volatile u16 *)(CFG_FLASH_BASE + (0x000002AA << 1)))
#define BIT_ERASE_DONE 0x00000080
#define BIT_RDY_MASK 0x00000080
#define BIT_PROGRAM_ERROR 0x00000020
#define BIT_TIMEOUT 0x80000000 /* our flag */
#define READY 1
#define ERR 2
#define TMO 4
/*-----------------------------------------------------------------------
*/
ulong flash_init (void)
{
int i, j;
ulong size = 0;
//因为我们只用一个nor flash 所以这里的 i=1
for (i = 0; i < CFG_MAX_FLASH_BANKS; i++) {
ulong flashbase = 0;
//文件include/configs/embendsky.h中：#define CONFIG_AMD_LV400 1 /* uncomment this if you have a LV400 flash */
flash_info[i].flash_id =
#if defined(CONFIG_AMD_LV400)
//include/flash.h中对flash的MANUFACT，VENDMASK，TYPEMASK有定义，主要是flash的ID
(AMD_MANUFACT & FLASH_VENDMASK) |
(AMD_ID_LV400B & FLASH_TYPEMASK);
#elif defined(CONFIG_AMD_LV800)
(AMD_MANUFACT & FLASH_VENDMASK) |
(AMD_ID_LV800B & FLASH_TYPEMASK);
#else
#error "Unknown flash configured"
#endif
//flash_info数据结构定义在include/flash.h中，主要存储，记录flash的一些基本信息
flash_info[i].size = FLASH_BANK_SIZE;
flash_info[i].sector_count = CFG_MAX_FLASH_SECT;
//memset函数 作用是在一段内存块中填充某个给定的值，它对较大的结构体或数组进行清零操作的一种最快方法
//下句意思是：把此flash 清零
memset (flash_info[i].protect, 0, CFG_MAX_FLASH_SECT);
//下面是确定flash的基址
if (i == 0)
////#define PHYS_FLASH_1 0x00000000 /* Flash Bank #1 */
flashbase = PHYS_FLASH_1;
else
panic ("configured too many flash banks!\n");
// for(j=0; j<11; j++)
//Am29LV400作为启动flash时有两种方式：top boot block sector和bottom boot block sector
//具体的启动方式与具体的硬件连接有关，此文中我们采用的是bottom boot block sector
//总的来说 下面的for循环就是 、确定各个sector的开始与结束地址，详见Am29LV400手册
//因为前三个sector的大小不一致分别是16KB，8KB，8KB，64KB，64KB，64KB，64KB，64KB，64KB，64KB，64KB，
for (j = 0; j < flash_info[i].sector_count; j++) {
if (j <= 3) {
/* 1st one is 16 KB */
if (j == 0) {
flash_info[i].start[j] =
flashbase + 0;
}
/* 2nd and 3rd are both 8 KB */
if ((j == 1) || (j == 2)) {
flash_info[i].start[j] =
flashbase + 0x4000 + (j -
1) *
0x2000;//8KB
}
/* 4th 32 KB */
if (j == 3) {
flash_info[i].start[j] =
flashbase + 0x8000;
}
} else {
flash_info[i].start[j] =
flashbase + (j - 3) * MAIN_SECT_SIZE;
}
}
size += flash_info[i].size;
}
//flash_protect函数，
flash_protect (FLAG_PROTECT_SET,
CFG_FLASH_BASE,
CFG_FLASH_BASE + monitor_flash_len - 1,
&flash_info[0]);
flash_protect (FLAG_PROTECT_SET,
CFG_ENV_ADDR,
CFG_ENV_ADDR + CFG_ENV_SIZE - 1, &flash_info[0]);
//返回flash的存储大小
return size;
}
/*-----------------------------------------------------------------------
*/
//打印flash的必要信息
void flash_print_info (flash_info_t * info)
{
int i;
//判断flash的型号
switch (info->flash_id & FLASH_VENDMASK) {
case (AMD_MANUFACT & FLASH_VENDMASK):
printf ("AMD: ");
break;
default:
printf ("Unknown Vendor ");
break;
}
//判断flash的存储大小
switch (info->flash_id & FLASH_TYPEMASK) {
case (AMD_ID_LV400B & FLASH_TYPEMASK):
printf ("1x Amd29LV400BB (4Mbit)\n");
break;
case (AMD_ID_LV800B & FLASH_TYPEMASK):
printf ("1x Amd29LV800BB (8Mbit)\n");
break;
default:
printf ("Unknown Chip Type\n");
goto Done;
break;
}
//打印flash的bit位数和sect的个数
printf (" Size: %ld MB in %d Sectors\n",
info->size >> 20, info->sector_count);
//打印各个sect的起始地址
printf (" Sector Start Addresses:");
for (i = 0; i < info->sector_count; i++) {
if ((i % 5) == 0) {
printf ("\n ");
}
printf (" %08lX%s", info->start[i],
info->protect[i] ? " (RO)" : " ");
}
printf ("\n");
Done:;
}
/*-----------------------------------------------------------------------
*/
//flash的擦出操作
// 存储flash信息 擦出开始 擦除结束
int flash_erase (flash_info_t * info, int s_first, int s_last)
{
ushort result;
int iflag, cflag, prot, sect;
int rc = ERR_OK;
int chip;
/* first look for protection bits */
//flash擦出前，要判断flash的状态，一边进一步的操作
if (info->flash_id == FLASH_UNKNOWN)
return ERR_UNKNOWN_FLASH_TYPE;
if ((s_first < 0) || (s_first > s_last)) {
return ERR_INVAL;
}
if ((info->flash_id & FLASH_VENDMASK) !=
(AMD_MANUFACT & FLASH_VENDMASK)) {
return ERR_UNKNOWN_FLASH_VENDOR;
}
prot = 0;
//下面的for循环就是查找s_first和 s_last之间被保护的sect数
for (sect = s_first; sect <= s_last; ++sect) {
if (info->protect[sect]) {
prot++;
}
}
//如果port>0即 又被保护的sect，那是不能被擦除的返回ERR_PROTECTED错误
if (prot)
return ERR_PROTECTED;
/*
* Disable interrupts which might cause a timeout
* here. Remember that our exception vectors are
* at address 0 in the flash, and we don't want a
* (ticker) exception to happen while the flash
* chip is in programming mode.
*/
//函数icache_status ()在cpu/ARM920T/cpu.c中
//cflag中保存了当前chche的状态
cflag = icache_status ();
//函数icache_disable在cpu/ARM920T/cpu.c中
//使能cache
icache_disable ();
//函数disable_interrupts ()在cpu/ARM920T/cpu.c中
//iflag保存了禁止interrupt的返回结果
iflag = disable_interrupts ();
/* Start erase on unprotected sectors */
for (sect = s_first; sect <= s_last && !ctrlc (); sect++) {
//打印要擦除的sect
printf ("Erasing sector %2d ... ", sect);
/* arm simple, non interrupt dependent timer */
//把现在的时间保存，具体的保存位置在函数lastdec = READ_TIMER();
reset_timer_masked ();
if (info->protect[sect] == 0) { /* not protected */
//addr指向此sect的起始地址
vu_short *addr = (vu_short *) (info->start[sect]);
MEM_FLASH_ADDR1 = CMD_UNLOCK1;
MEM_FLASH_ADDR2 = CMD_UNLOCK2;
MEM_FLASH_ADDR1 = CMD_ERASE_SETUP;
MEM_FLASH_ADDR1 = CMD_UNLOCK1;
MEM_FLASH_ADDR2 = CMD_UNLOCK2;
*addr = CMD_ERASE_CONFIRM;
/* wait until flash is ready */
chip = 0;
//下面的do-while循环就是准备等待flash ready
do {
result = *addr;
/* check timeout */
//get_timer_masked ()返回超时时间片，并判断是否超过我们设定的超时值
if (get_timer_masked () >
CFG_FLASH_ERASE_TOUT) {
MEM_FLASH_ADDR1 = CMD_READ_ARRAY;
chip = TMO; //flash超时
break;
}
if (!chip
&& (result & 0xFFFF) & BIT_ERASE_DONE)
chip = READY; //flash 已准备好
if (!chip
&& (result & 0xFFFF) & BIT_PROGRAM_ERROR)
chip = ERR; //flash 编程错误
} while (!chip);
MEM_FLASH_ADDR1 = CMD_READ_ARRAY;
if (chip == ERR) {
rc = ERR_PROG_ERROR;
goto outahere;
}
if (chip == TMO) {
rc = ERR_TIMOUT;
goto outahere;
}
printf ("ok.\n");
} else { /* it was protected */
printf ("protected!\n");
}
}
if (ctrlc ())
printf ("User Interrupt!\n");
outahere:
/* allow flash to settle - wait 10 ms */
udelay_masked (10000);
//开中断
if (iflag)
enable_interrupts ();
//使能flash
if (cflag)
icache_enable ();
//返回flash的erase结果
return rc;
}
/*-----------------------------------------------------------------------
* Copy memory to flash
*/
// flash基本信息 写入的地址 数据大小
static int write_hword (flash_info_t * info, ulong dest, ushort data)
{
//
vu_short *addr = (vu_short *) dest;
ushort result;
int rc = ERR_OK;
int cflag, iflag;
int chip;
/*
* Check if Flash is (sufficiently) erased
*/
result = *addr;//dest的地址赋值给result
if ((result & data) != data)
return ERR_NOT_ERASED;

/*
* Disable interrupts which might cause a timeout
* here. Remember that our exception vectors are
* at address 0 in the flash, and we don't want a
* (ticker) exception to happen while the flash
* chip is in programming mode.
*/
cflag = icache_status ();
icache_disable ();
iflag = disable_interrupts ();
MEM_FLASH_ADDR1 = CMD_UNLOCK1;
MEM_FLASH_ADDR2 = CMD_UNLOCK2;
MEM_FLASH_ADDR1 = CMD_UNLOCK_BYPASS;
*addr = CMD_PROGRAM;
*addr = data;
/* arm simple, non interrupt dependent timer */
reset_timer_masked ();
/* wait until flash is ready */
chip = 0;
do {
result = *addr;
/* check timeout */
if (get_timer_masked () > CFG_FLASH_ERASE_TOUT) {
chip = ERR | TMO;
break;
}
if (!chip && ((result & 0x80) == (data & 0x80)))
chip = READY;
if (!chip && ((result & 0xFFFF) & BIT_PROGRAM_ERROR)) {
result = *addr;
if ((result & 0x80) == (data & 0x80))
chip = READY;
else
chip = ERR;
}
} while (!chip);
*addr = CMD_READ_ARRAY;
if (chip == ERR || *addr != data)
rc = ERR_PROG_ERROR;
if (iflag)
enable_interrupts ();
if (cflag)
icache_enable ();
return rc;
}
/*-----------------------------------------------------------------------
* Copy memory to flash.
*/
int write_buff (flash_info_t * info, uchar * src, ulong addr, ulong cnt)
{
ulong cp, wp;
int l;
int i, rc;
ushort data;
wp = (addr & ~1); /* get lower word aligned address */
/*
* handle unaligned start bytes
*/
if ((l = addr - wp) != 0) {
data = 0;
for (i = 0, cp = wp; i < l; ++i, ++cp) {
data = (data >> 8) | (*(uchar *) cp << 8);
}
for (; i < 2 && cnt > 0; ++i) {
data = (data >> 8) | (*src++ << 8);
--cnt;
++cp;
}
for (; cnt == 0 && i < 2; ++i, ++cp) {
data = (data >> 8) | (*(uchar *) cp << 8);
}
if ((rc = write_hword (info, wp, data)) != 0) {
return (rc);
}
wp += 2;
}
/*
* handle word aligned part
*/
while (cnt >= 2) {
data = *((vu_short *) src);
if ((rc = write_hword (info, wp, data)) != 0) {
return (rc);
}
src += 2;
wp += 2;
cnt -= 2;
}
if (cnt == 0) {
return ERR_OK;
}
/*
* handle unaligned tail bytes
*/
data = 0;
for (i = 0, cp = wp; i < 2 && cnt > 0; ++i, ++cp) {
data = (data >> 8) | (*src++ << 8);
--cnt;
}
for (; i < 2; ++i, ++cp) {
data = (data >> 8) | (*(uchar *) cp << 8);
}
return write_hword (info, wp, data);
}
注：此falsh.c文件中涉及到的文件有：
include/configs/embendsky.h
include/flash.h
cpu/ARM920T/cpu.c
cpu/ARM920T/S3C2440/interrupt.c
include/common.h

其中include/flash.h中定义了重要数据结构如下所示：

typedef struct {
ulong size; /* total bank size in bytes */
ushort sector_count; /* number of erase units */
ulong flash_id; /* combined device & manufacturer code */
ulong start[CFG_MAX_FLASH_SECT]; /* physical sector start addresses */
uchar protect[CFG_MAX_FLASH_SECT]; /* sector protection status */
#ifdef CFG_FLASH_CFI
uchar portwidth; /* the width of the port */
uchar chipwidth; /* the width of the chip */
ushort buffer_size; /* # of bytes in write buffer */
ulong erase_blk_tout; /* maximum block erase timeout */
ulong write_tout; /* maximum write timeout */
ulong buffer_write_tout; /* maximum buffer write timeout */
ushort vendor; /* the primary vendor id */
ushort cmd_reset; /* Vendor specific reset command */
ushort interface; /* used for x8/x16 adjustments */
ushort legacy_unlock; /* support Intel legacy (un)locking */
#endif
} flash_info_t;
此数据结构保存了flash的重要信息，在flash的具体操作中都会使用到，另外flash。h中还定了操作flash的必须的操作码与命令吗，标识码。
include/configs/embendsky.h中定义了对于S3c2440的一些配置文件：除了flash，还有其他的：LCD，DM9000，等等，需要用到时再仔细看。
cpu/ARM920T/cpu.c中包含了cache的操作，操作CP15协处理器的函数，CPU的初始化工作。
cpu/ARM920T/S3C2440/interrupt.c中包含了读写芯片的时间，中断的处理中等。
include/common.h定义了素有要用到的函数的原型声明。