Ok, I've done some progress by now. It seems like omap_mux doesn't exists anymore, the new system to configure the MUX is through Device Tree Overlays. I have been reading some post about how to use them in Beaglebone boards like
http://www.valvers.com/embedded-linux/beaglebone-black/step04-gpio/ and
http://interactingobjects.com/ds18b20-temperature-sensor-on-a-beaglebone-black-running-ubuntu/. So I downloaded the OMAP4 Technical Reference Manual (download here:
http://www.ti.com/lit/ug/swpu235ab/swpu235ab.pdf). Table 18-504 show the UART4 control register. Based on that and the urls above I created and compiled the following Device Tree Overlay:
$this->bbcode_second_pass_code('', '// Util: http://lxr.free-electrons.com/source/arch/arm/boot/dts/omap4-panda-es.dts
// http://www.valvers.com/embedded-linux/beaglebone-black/step04-gpio/
/dts-v1/;
/plugin/;
/ {
model = "TI OMAP4 PandaBoard-ES";
compatible = "ti,omap4-panda-es", "ti,omap4460";
part-number = "ANDRES-IO";
fragment@0 {
target = <&am33xx_pinmux>;
__overlay__ {
uart4_pins: pinmux_uart4_pins {
pinctrl-single,pins = <
0x15C 0x00 // kernel pin 142 (uart4 tx y rx - address 0x4A10 015C)
>;
};
};
};
fragment@1 {
target = <&ocp>;
__overlay__ {
uart4_pins_helper {
compatible = "panda-pinmux-helper";
pinctrl-names = "default";
pinctrl-0 = <&uart4_pins>;
status = "okay";
};
};
};
};')
I copied the compiled file to /lib/firmware/ but after that I don't know how to use or enable it. Beaglebone boards have bone_capemgr but I can't see such a thing in Pandaboard.