SDHCI_CLOCK_CONTROL
RD1(slot, SDHCI_WAKE_UP_CONTROL), RD2(slot, SDHCI_CLOCK_CONTROL));
clk = RD2(slot, SDHCI_CLOCK_CONTROL);
WR2(slot, SDHCI_CLOCK_CONTROL, clk & ~SDHCI_CLOCK_CARD_EN);
WR2(slot, SDHCI_CLOCK_CONTROL, clk);
WR2(slot, SDHCI_CLOCK_CONTROL, clk);
while (!((clk = RD2(slot, SDHCI_CLOCK_CONTROL))
WR2(slot, SDHCI_CLOCK_CONTROL, clk);