sequence on CMD42

SD card 的溝通也是要靠 Address 的， (RCA : Relative Card Address)，但是 address 0x00 是 broadcast address，所有的 card 都要收。

CMD7 (SELECT_DESELECT) 是用來 toggle SD card 進入/退出 Transfer Mode 。

Card Lock/Unlock Command 類似 Block Write Command。
其中 transfer 的 data 部份，就是 password, setting... etc。

所以 CMD42 的 Response 也跟 Block Write Command 的 Result 一樣 ？

Card Identification.. 然後 Configuration...然後進 Transfer state..

procedure :

先作 setting password

---

Linux 真是偉大，在某一版看到 implement，但是好像沒有 接受
http://groups.google.com.tw/group/linux.kernel/browse_thread/thread/7ddefc84c21ede84/d47cd82a306fd9d8?q=mmc_lock_unlock#d47cd82a306fd9d8

int mmc_lock_unlock(struct mmc_card *card, struct key *key, int mode)
+{
+       struct mmc_request mrq;
+       struct mmc_command cmd;
+       struct mmc_data data;
+       struct scatterlist sg;
+       struct mmc_key_payload *mpayload;
+       unsigned long erase_timeout;
+       int err, data_size;
+       u8 *data_buf;
+
+       mpayload = NULL;
+       data_size = 1;
+       if (mode != MMC_LOCK_MODE_ERASE) {
+               mpayload = rcu_dereference(key->payload.data);
+               data_size = 2 + mpayload->datalen;
+       }
+
+       data_buf = kmalloc(data_size, GFP_KERNEL);
+       if (!data_buf)
+               return -ENOMEM;
+       memset(data_buf, 0, data_size);
+
+       data_buf[0] = mode;
+       if (mode != MMC_LOCK_MODE_ERASE) {
+               data_buf[1] = mpayload->datalen;
+               memcpy(data_buf + 2, mpayload->data, mpayload->datalen);
+       }
+
+       memset(&cmd, 0, sizeof(struct mmc_command));
+
+       cmd.opcode = MMC_SET_BLOCKLEN;
+       cmd.arg = data_size;
+       cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+       err = mmc_wait_for_cmd(card->host, &cmd, CMD_RETRIES);
+       if (err != MMC_ERR_NONE)
+               goto out;
+
+       memset(&cmd, 0, sizeof(struct mmc_command));
+
+       cmd.opcode = MMC_LOCK_UNLOCK;
+       cmd.arg = 0;
+       cmd.flags = MMC_RSP_R1B | MMC_CMD_ADTC;
+
+       memset(&data, 0, sizeof(struct mmc_data));
+
+       mmc_set_data_timeout(&data, card, 1);
+
+       data.blksz = data_size;
+       data.blocks = 1;
+       data.flags = MMC_DATA_WRITE;
+       data.sg = &sg;
+       data.sg_len = 1;
+
+       memset(&mrq, 0, sizeof(struct mmc_request));
+
+       mrq.cmd = &cmd;
+       mrq.data = &data;
+
+       sg_init_one(&sg, data_buf, data_size);
+       err = mmc_wait_for_req(card->host, &mrq);
+       if (err != MMC_ERR_NONE)
+               goto out;
+
+       memset(&cmd, 0, sizeof(struct mmc_command));
+
+       cmd.opcode = MMC_SEND_STATUS;
+       cmd.arg = card->rca << 16;
+       cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+
+       /* set timeout for forced erase operation to 3 min. (see MMC spec) */
+       erase_timeout = jiffies + 180 * HZ;
+       do {
+               /* we cannot use "retries" here because the
+                * R1_LOCK_UNLOCK_FAILED bit is cleared by subsequent reads to
+                * the status register, hiding the error condition */
+               err = mmc_wait_for_cmd(card->host, &cmd, 0);
+               if (err != MMC_ERR_NONE)
+                       break;
+               /* the other modes don't need timeout checking */
+               if (mode != MMC_LOCK_MODE_ERASE)
+                       continue;
+               if (time_after(jiffies, erase_timeout)) {
+                       dev_dbg(&card->dev, "forced erase timed out\n");
+                       err = MMC_ERR_TIMEOUT;
+                       break;
+               }
+       } while (!(cmd.resp[0] & R1_READY_FOR_DATA));
+       if (cmd.resp[0] & R1_LOCK_UNLOCK_FAILED) {
+               dev_dbg(&card->dev, "LOCK_UNLOCK operation failed\n");
+               err = MMC_ERR_FAILED;
+       }
+
+       if (cmd.resp[0] & R1_CARD_IS_LOCKED)
+               mmc_card_set_locked(card);
+       else
+               mmc_card_clear_locked(card);
+
+out:
+       kfree(data_buf);
+
+       return err;
+}

裡面有完整的CMD42 的 command sequence..
但是這段 code 在linux kernel 中找不到...

這一個Thread 有相關的討論..