一、 spi_flash uboot驅動的一個應用實例
1. spi應用程序在操作之前調用spi_flash_probe去初始化spi_flash
2. 初始化完畢即可讀寫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);
//操作讀寫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驅動分析
spi初始化入口函數：
struct spi_flash *spi_flash_probe(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsignedint spi_mode)
{
1. 配置spi控制器總線、cs片選、速率、spi模式
2. 讀取spi flash的設備ID號
3. 根據ID號查表去匹配不同芯片的配置屬性。找到對應芯片的初始化鉤子函數。（注：見代碼段1）
4. 調用SPI flash初始化函數，去匹配芯片名稱、配置頁、扇區、塊的大小，配置flash的讀、寫、擦除鉤子函數。（注：見代碼段2）
5. 如果flash容量大於16m，則設置flash 爲4字節模式
6. 初始化spi flash完畢，釋放spi總線。
}
Spi讀寫函數：
（注：這個函數的被調 見代碼段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;
//發送spi flash 命令
ret = spi_xfer(spi, cmd_len * 8, cmd,NULL, flags);
//發送spi flash 數據
if (data_len != 0) {
ret = spi_xfer(spi, data_len* 8, data_out, data_in, SPI_XFER_END);
}
return ret;
}
spi_xfer的實現依賴於具體的處理器。主要的功能是順序的把數據寫入到spi總線。
代碼段1：
這個結構體在spi_flash_probe初始化函數的第三步使用。根據芯片廠商類型掛鉤子函數。
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
};
代碼段2：
以華邦爲例，華邦的SPI FLASH初始化函數
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;
//找芯片型號
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;
//掛載鉤子函數,下面3個函數是spi flash的讀寫擦除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;
}
代碼段3：
讀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;
//構造命令的格式流
spi_flash_addr(flash,offset, cmd);
//寫入數據到spi總線
return spi_flash_read_common(flash,cmd, idx, data, len);
}
spi flash的讀寫和擦除理論上必須是把物理地址轉換成頁和偏移去讀、寫和擦除。
由於很多芯片的頁大小就是0xff=255個字節。所以直接傳地址和把地址轉換成頁和偏移的結果是等價的。
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;
//使能總線
spi_claim_bus(spi);
//讀數據
ret = spi_flash_cmd_read(spi, cmd,cmd_len, data, data_len);
//釋放總線
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);
}
代碼段4：
Spi flash的寫操作
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;
}
//寫使能
ret =spi_flash_cmd_write_enable(flash);
//寫
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;
}
代碼段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;
//擦除必須是整塊的擦除
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;
}