CLK_DIV_MASK
clk_reg |= CLK_DIV_MASK;
div->shift = __ffs(CLK_DIV_MASK);
div->width = __builtin_popcountl(CLK_DIV_MASK);
for (div = 0; div < CLK_DIV_MASK; ++div) {
mmc->f_min = DIV_ROUND_CLOSEST(host->sysclk, CLK_DIV_MASK * 2);