SDHCI_FSL_TBPTR_WND_START_SHIFT
reg &= ~(SDHCI_FSL_TBPTR_WND_MASK << SDHCI_FSL_TBPTR_WND_START_SHIFT);
reg |= wnd_start << SDHCI_FSL_TBPTR_WND_START_SHIFT;
wnd_start = reg >> SDHCI_FSL_TBPTR_WND_START_SHIFT;