一、 spi_flash uboot驱动的一个应用实例
1. spi应用程序在操作之前调用spi_flash_probe去初始化spi_flash
2. 初始化完毕即可读写spi flash
void spl_spi_load_image(void)
{
//初始化SPI FLASH
flash =spi_flash_probe(CONFIG_SPL_SPI_BUS, CONFIG_SPL_SPI_CS,
CONFIG_SF_DEFAULT_SPEED,SPI_MODE_3);
//操作读写flash
/*Load u-boot, mkimage header is 64 bytes. */
spi_flash_read(flash, CONFIG_SYS_SPI_U_BOOT_OFFS,0x40,
(void*) header);
spl_parse_image_header(header);
……
}
二、 spi flash驱动分析
spi初始化入口函数：
struct spi_flash *spi_flash_probe(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsignedint spi_mode)
{
1. 配置spi控制器总线、cs片选、速率、spi模式
2. 读取spi flash的设备ID号
3. 根据ID号查表去匹配不同芯片的配置属性。找到对应芯片的初始化钩子函数。（注：见代码段1）
4. 调用SPI flash初始化函数，去匹配芯片名称、配置页、扇区、块的大小，配置flash的读、写、擦除钩子函数。（注：见代码段2）
5. 如果flash容量大于16m，则设置flash 为4字节模式
6. 初始化spi flash完毕，释放spi总线。
}
Spi读写函数：
（注：这个函数的被调 见代码段3）
static int spi_flash_read_write(struct spi_slave *spi,
const u8*cmd, size_t cmd_len,
const u8*data_out, u8 *data_in,
size_tdata_len)
{
if (data_len == 0)
flags |= SPI_XFER_END;
//发送spi flash 命令
ret = spi_xfer(spi, cmd_len * 8, cmd,NULL, flags);
//发送spi flash 数据
if (data_len != 0) {
ret = spi_xfer(spi, data_len* 8, data_out, data_in, SPI_XFER_END);
}
return ret;
}
spi_xfer的实现依赖于具体的处理器。主要的功能是顺序的把数据写入到spi总线。
代码段1：
这个结构体在spi_flash_probe初始化函数的第三步使用。根据芯片厂商类型挂钩子函数。
static const struct {
const u8 shift;
const u8 idcode;
struct spi_flash *(*probe) (structspi_slave *spi, u8 *idcode);
}flashes[] = {
/* Keep it sorted by define name */
#ifdefCONFIG_SPI_FLASH_ATMEL
{ 0, 0x1f, spi_flash_probe_atmel, },
#endif
#ifdefCONFIG_SPI_FLASH_EON
{ 0, 0x1c, spi_flash_probe_eon, },
#endif
#ifdefined(CONFIG_SPI_FLASH_MACRONIX) || defined(CONFIG_SPI_FLASH_MACRONIX_NS)
{ 0, 0xc2, spi_flash_probe_macronix, },
#endif
#ifdefCONFIG_SPI_FLASH_SPANSION
{ 0, 0x01, spi_flash_probe_spansion, },
#endif
#ifdefCONFIG_SPI_FLASH_SST
{ 0, 0xbf, spi_flash_probe_sst, },
#endif
#ifdefined(CONFIG_SPI_FLASH_STMICRO) || defined(CONFIG_SPI_FLASH_STMICRO_NS)
{ 0, 0x20, spi_flash_probe_stmicro, },
#endif
#ifdefCONFIG_SPI_FLASH_WINBOND
{ 0, 0xef, spi_flash_probe_winbond, },
#endif
#ifdefCONFIG_SPI_FRAM_RAMTRON
{ 6, 0xc2, spi_fram_probe_ramtron, },
# undefIDCODE_CONT_LEN
# defineIDCODE_CONT_LEN 6
#endif
/* Keep it sorted by best detection */
#ifdefined(CONFIG_SPI_FLASH_STMICRO) || defined(CONFIG_SPI_FLASH_STMICRO_NS)
{ 0, 0xff, spi_flash_probe_stmicro, },
#endif
#ifdefCONFIG_SPI_FRAM_RAMTRON_NON_JEDEC
{ 0, 0xff, spi_fram_probe_ramtron, },
#endif
};
代码段2：
以华邦为例，华邦的SPI FLASH初始化函数
struct spi_flash *spi_flash_probe_winbond(struct spi_slave *spi, u8 *idcode)
{
const struct winbond_spi_flash_params*params;
struct spi_flash *flash;
unsigned int i;
//找芯片型号
for (i = 0; i <ARRAY_SIZE(winbond_spi_flash_table); i++) {
params =&winbond_spi_flash_table[i];
if (params->id ==((idcode[1] << 8) | idcode[2]))
break;
}
flash->spi = spi;
flash->name = params->name;
//挂载钩子函数,下面3个函数是spi flash的读写擦除API
flash->write =spi_flash_cmd_write_multi;
flash->erase= spi_flash_cmd_erase;
flash->read= spi_flash_cmd_read_fast;
flash->page_size= 256;
flash->sector_size= 4096;
flash->size = 4096* 16 * params->nr_blocks;
return flash;
}
代码段3：
读FLASH的流程：
1.
int spi_flash_cmd_read_fast(struct spi_flash *flash, u32 offset,
size_t len, void *data)
{
u8 cmd[6]={0};
int idx = flash->mode_4byte?sizeof(cmd):sizeof(cmd)-1;
cmd[0] = CMD_READ_ARRAY_FAST;
//构造命令的格式流
spi_flash_addr(flash,offset, cmd);
//写入数据到spi总线
return spi_flash_read_common(flash,cmd, idx, data, len);
}
spi flash的读写和擦除理论上必须是把物理地址转换成页和偏移去读、写和擦除。
由于很多芯片的页大小就是0xff=255个字节。所以直接传地址和把地址转换成页和偏移的结果是等价的。
static void spi_flash_addr(struct spi_flash *flash,u32 addr, u8 *cmd)
{
/* cmd[0] is actual command */
if(flash->mode_4byte){
cmd[1] = addr >> 24;
cmd[2] = addr >> 16;
cmd[3] = addr >> 8;
cmd[4] = addr >> 0;
}else{
cmd[1] = addr >> 16;
cmd[2] = addr >> 8;
cmd[3] = addr >> 0;
}
}
2.
int spi_flash_read_common(struct spi_flash *flash, const u8 *cmd,
size_t cmd_len, void *data,size_t data_len)
{
struct spi_slave *spi = flash->spi;
int ret;
//使能总线
spi_claim_bus(spi);
//读数据
ret = spi_flash_cmd_read(spi, cmd,cmd_len, data, data_len);
//释放总线
spi_release_bus(spi);
return ret;
}
3.
int spi_flash_cmd_read(struct spi_slave *spi, const u8 *cmd,
size_t cmd_len, void *data,size_t data_len)
{
return spi_flash_read_write(spi, cmd,cmd_len, NULL, data, data_len);
}
代码段4：
Spi flash的写操作
int spi_flash_cmd_write_multi(struct spi_flash *flash, u32 offset,
size_t len, const void *buf)
{
int idx = flash->mode_4byte?sizeof(cmd):sizeof(cmd)-1;
page_size = flash->page_size;
page_addr = offset / page_size;
byte_addr = offset % page_size;
ret = spi_claim_bus(flash->spi);
cmd[0] = CMD_PAGE_PROGRAM;
for (actual = 0; actual < len;actual += chunk_len) {
if(flash->mode_4byte){
cmd[1] = page_addr>> 16;
cmd[2] = page_addr >> 8;
cmd[3] = page_addr;
cmd[4] = byte_addr;
}else{
cmd[1] = page_addr>> 8;
cmd[2] = page_addr;
cmd[3] = byte_addr;
}
//写使能
ret =spi_flash_cmd_write_enable(flash);
//写
ret =spi_flash_cmd_write(flash->spi, cmd, idx,
buf + actual, chunk_len);
//等待完成
ret =spi_flash_cmd_wait_ready(flash, SPI_FLASH_PROG_TIMEOUT);
page_addr++;
byte_addr = 0;
}
spi_release_bus(flash->spi);
return ret;
}
代码段5：
Spi flash的擦除
intspi_flash_cmd_erase(struct spi_flash *flash, u32 offset, size_t len)
{
int idx = flash->mode_4byte?sizeof(cmd):sizeof(cmd)-1;
erase_size = flash->sector_size;
//擦除必须是整块的擦除
if (offset % erase_size || len %erase_size) {
debug("SF: Eraseoffset/length not multiple of erase size\n");
return -1;
}
ret = spi_claim_bus(flash->spi);
if (erase_size == 4096)
cmd[0] = CMD_ERASE_4K;
else
cmd[0] = CMD_ERASE_64K;
start = offset;
end = start + len;
while (offset < end) {
spi_flash_addr(flash,offset,cmd);
offset += erase_size;
ret =spi_flash_cmd_write_enable(flash);
ret =spi_flash_cmd_write(flash->spi, cmd,idx, NULL, 0);
ret =spi_flash_cmd_wait_ready(flash, SPI_FLASH_PAGE_ERASE_TIMEOUT);
}
out:
spi_release_bus(flash->spi);
return ret;
}
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