ASPEED_PECI_CTRL_CLK_DIV_MASK
val &= ~ASPEED_PECI_CTRL_CLK_DIV_MASK;
val |= FIELD_PREP(ASPEED_PECI_CTRL_CLK_DIV_MASK, clk_div_exp);
clk_div_exp = FIELD_GET(ASPEED_PECI_CTRL_CLK_DIV_MASK, reg);