CMD0 RESET
发送CMD0 eMMC会进入自行复位busy状态后进入idle状态
#define MMC_CMD_GO_IDLE_STATE 0
struct mmc_cmd cmd;
int err;
udelay(1000);
cmd.cmdidx = MMC_CMD_GO_IDLE_STATE;
cmd.cmdarg = 0;
cmd.resp_type = MMC_RSP_NONE;
err = mmc_send_cmd(mmc, &cmd, NULL);
if (err)
return err;
udelay(2000);
CMD1 CHECK_BUSY
CMD1命令得到eMMC的OCR寄存器值
代码发送命令,bit[31]为1表示ready状态,为0表示busy状态
#define MMC_CMD_SEND_OP_COND 1
cmd.cmdidx = MMC_CMD_SEND_OP_COND;
cmd.resp_type = MMC_RSP_R3;
cmd.cmdarg = 0;
if (use_arg && !mmc_host_is_spi(mmc))
cmd.cmdarg = OCR_HCS |
(mmc->cfg->voltages &
(mmc->ocr & OCR_VOLTAGE_MASK)) |
(mmc->ocr & OCR_ACCESS_MODE);
err = mmc_send_cmd(mmc, &cmd, NULL);
if (err)
return err;
mmc->ocr = cmd.response[0];
CMD2 GET_CID
发送CMD2进行认证(获取CID),寄存器描述,128比特,16字节
代码发送命令
#define MMC_CMD_ALL_SEND_CID 2
/* Put the Card in Identify Mode */
cmd.cmdidx = mmc_host_is_spi(mmc) ? MMC_CMD_SEND_CID :
MMC_CMD_ALL_SEND_CID; /* cmd not supported in spi */
cmd.resp_type = MMC_RSP_R2;
cmd.cmdarg = 0;
err = mmc_send_cmd(mmc, &cmd, NULL);
if (err)
return err;
memcpy(mmc->cid, cmd.response, 16);
打印出CID数据
printf("Manufacturer ID: %x\n", mmc->cid[0] >> 24);
printf("OEM: %x\n", (mmc->cid[0] >> 8) & 0xffff);
printf("Name: %c%c%c%c%c \n", mmc->cid[0] & 0xff,
(mmc->cid[1] >> 24), (mmc->cid[1] >> 16) & 0xff,
(mmc->cid[1] >> 8) & 0xff, mmc->cid[1] & 0xff);
Manufacturer ID: fe
OEM: 14e
Name: P1XXX
CMD3 STBY
然后发送CMD3,之后eMMC进入stby状态
#define SD_CMD_SEND_RELATIVE_ADDR 3
if (!mmc_host_is_spi(mmc)) { /* cmd not supported in spi */
cmd.cmdidx = SD_CMD_SEND_RELATIVE_ADDR;
cmd.cmdarg = mmc->rca << 16;
cmd.resp_type = MMC_RSP_R6;
err = mmc_send_cmd(mmc, &cmd, NULL);
if (err)
return err;
if (IS_SD(mmc))
mmc->rca = (cmd.response[0] >> 16) & 0xffff;
}
CMD7
使用CMD7进入transfer状态,此命令用来设置eMMC的状态,因为当使用CMD0使eMMC复位后,eMMC处于idle或pre_idle状态,如果需要数据传输,必须将eMMC置于transfer_state
#define MMC_CMD_SELECT_CARD 7
/* Select the card, and put it into Transfer Mode */
if (!mmc_host_is_spi(mmc)) { /* cmd not supported in spi */
cmd.cmdidx = MMC_CMD_SELECT_CARD;
cmd.resp_type = MMC_RSP_R1;
cmd.cmdarg = mmc->rca << 16;
err = mmc_send_cmd(mmc, &cmd, NULL);
if (err)
return err;
}
CMD8
CMD8命令用来获取EXT_CSD的值,虽然回复为R1,但是EXT_CSD的512字节值会被读取并存储到内存里,然后用户可以根据这些数据分析出eMMC当前支持的各种参数和状态,EXT_CSD是eMMC4之后才引入的寄存器组
struct mmc_cmd cmd;
struct mmc_data data;
int err;
/* Get the Card Status Register */
cmd.cmdidx = MMC_CMD_SEND_EXT_CSD;
cmd.resp_type = MMC_RSP_R1;
cmd.cmdarg = 0;
data.dest = (char *)ext_csd;
data.blocks = 1;
data.blocksize = MMC_MAX_BLOCK_LEN;
data.flags = MMC_DATA_READ;
err = mmc_send_cmd(mmc, &cmd, &data);
CMD9 GET_CSD
获取CSD寄存器值,描述如下
代码实现
#define MMC_CMD_SEND_CSD 9
/* Get the Card-Specific Data */
cmd.cmdidx = MMC_CMD_SEND_CSD;
cmd.resp_type = MMC_RSP_R2;
cmd.cmdarg = mmc->rca << 16;
err = mmc_send_cmd(mmc, &cmd, NULL);
/* Waiting for the ready status */
mmc_send_status(mmc, timeout);
if (err)
return err;
mmc->csd[0] = cmd.response[0];
mmc->csd[1] = cmd.response[1];
mmc->csd[2] = cmd.response[2];
mmc->csd[3] = cmd.response[3];