MESON_PWM_MISC_AB_A_CLK_DIV
clk_div = __SHIFTOUT(val, MESON_PWM_MISC_AB_A_CLK_DIV);
val &= ~MESON_PWM_MISC_AB_A_CLK_DIV;
old_div = __SHIFTOUT(val, MESON_PWM_MISC_AB_A_CLK_DIV);
val |= __SHIFTIN(clk_div, MESON_PWM_MISC_AB_A_CLK_DIV);