https://github.com/torvalds/linux/blob/master/arch/arm/boot/dts/sun8i-v3s.dtsi
mmc0_pins: mmc0-pins {
pins = "PF0", "PF1", "PF2", "PF3",
"PF4", "PF5";
function = "mmc0";
drive-strength = <30>; /*10, 20, 30, 40mA 四个档次*/
bias-pull-up;
};
代码实现:
https://github.com/torvalds/linux/blob/master/drivers/pinctrl/sunxi/pinctrl-sunxi.c
static int sunxi_pctrl_parse_drive_prop(struct device_node *node)
{
u32 val;
/* Try the new style binding */
if (!of_property_read_u32(node, "drive-strength", &val)) {
/* We can't go below 10mA ... */
if (val < 10)
return -EINVAL;
/* ... and only up to 40 mA ... */
if (val > 40)
val = 40;
/* by steps of 10 mA */
return rounddown(val, 10);
}
/* And then fall back to the old binding */
if (of_property_read_u32(node, "allwinner,drive", &val))
return -EINVAL;
return (val + 1) * 10;
}离线