SD/MMC驅動2(SD檢測)

SD卡座資料（帶檢測引腳）

 

 

 

可將CD引腳通過上拉電阻接到VDD用於SD的插入和拔出檢測：

當拔出SD時，CD引腳的電壓為VDD，否則為GND。

 

 

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void mmc_rescan(struct work_struct *work)
{
 struct mmc_host *host =
  container_of(work, struct mmc_host, detect.work);
 u32 ocr;
 int err;

 mmc_bus_get(host);

 if (host->bus_ops == NULL) {  //When we find a MMC,when

 

......

/*
   * ...and finally MMC.
   */
  err = mmc_send_op_cond(host, 0, &ocr);
  if (!err) {
   if (mmc_attach_mmc(host, ocr))
    mmc_power_off(host);
   goto out; 
  }

  mmc_release_host(host);
  mmc_power_off(host);

 

 } else {  //remove the MMC
  if (host->bus_ops->detect && !host->bus_dead)
   host->bus_ops->detect(host);

  mmc_bus_put(host);
 }

 

 

(a).When we find a new MMC card:

mmc_attach_mmc->mmc_add_card->mmc_bus_probe->mmc_blk_probe

 

Add the MMC device node danamicly;

 

(b).When we remove a MMC card:

host->bus_ops->detect(host)->mmc_detect->mmc_remove->mmc_remove_card->mmc_bus_remove->mmc_blk_remove

Remove the MMC device node.