On 2014-04-29 10:36, Peter TB Brett wrote:
Hi all,
We have several pieces of software that make use of the
/sys/class/gpio userspace interface to the GPIO subsystem.
One important prerequisite to being able to use the userspace GPIO
interface is to be able to put the corresponding package pins into
GPIO mode, by modifying the chip's mux settings.
With Fedora 19 on the Pandaboard, we were able to achieve this by
poking around in /sys/kernel/debug/omap_mux. However, when running
Fedora 20, this directory is empty. My assumption is that this
functionality has been subsumed by the pinctrl subsystem in recent
kernels. Unfortunately, there doesn't seem to be any documented
userspace API.
I'd greatly appreciate it if someone could give me some pointers about
how to deal with this issue!
I'm still looking for a solution to this problem!
Is there any way that I can simply amend the device tree in order to
change a couple of mux settings?
I've figured out that I would need a stanza that looks something like:
&omap4_pmx_core
{
foo_pins: pinmux_foo_pins {
pinctrl-single,pins = <
0x5e (PIN_INPUT | MUX_MODE3) /* gpmc_ad15.gpio_39 */ /* IRQ */
0x12e (PIN_INPUT | MUX_MODE3) /* i2c4_scl.gpio_132 */ /* RST */
};
};
But I can't work out what else I need to modify in order for these mux
settings to take effect.
Thanks for any pointers!
Peter
--
Dr Peter Brett <peter@xxxxxxxxxxxxx>
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