linux kernel: regulator consumer usage from userspace - linux

Question

I have some kind of driver in user space:
program talk via some interface(rs232) with device.
Also I have pin(gpio) to switch on/off this device.
I do not code in my program concrete gpio, to make it more portable,
so I modify device tree description of my board,
and describe regulator-fixed, after that I thought to use
userspace-consumer driver to control power on/off,
but looks like that not kernel developers expected
(link to discussion of similar problem, not my):
http://patchwork.ozlabs.org/patch/374912/
So how should I control switch on/off
of my device from user space without adding to my program
information about what conrete gpio used to switch on/off device?
More details:
In my board dts I described my pin like this:
regulator-deviceX {
status = "okay";
compatible = "regulator-fixed";
regulator-name = "DEV_X_ON#";
regulator-min-microvolt = <3300000>;
regulator-max-microvolt = <3300000>;
gpio = <&gpio5 4 GPIO_ACTIVE_LOW>;
};
And of course, after boot "gpio = <&gpio5 4 GPIO_ACTIVE_LOW>" was
locked by the kernel, and it is impossible to use it via /sys/class/gpio interface.
Bad think about such approach, that is impossible (or I don't see how) to
change regulator state from user space, as you can see "state" is read only file.
root#board:/sys/class/regulator/regulator.1# ls -l
lrwxrwxrwx 1 root root 0 May 3 03:32 device -> ../../../regulator-deviceX
-r--r--r-- 1 root root 4096 May 3 03:32 microvolts
-r--r--r-- 1 root root 4096 May 3 03:32 name
-r--r--r-- 1 root root 4096 May 3 03:32 num_users
drwxr-xr-x 2 root root 0 May 3 03:32 power
-r--r--r-- 1 root root 4096 May 3 03:32 state
lrwxrwxrwx 1 root root 0 May 3 03:25 subsystem -> ../../../../class/regulator
-r--r--r-- 1 root root 4096 May 3 03:32 suspend_disk_state
-r--r--r-- 1 root root 4096 May 3 03:32 suspend_mem_state
-r--r--r-- 1 root root 4096 May 3 03:32 suspend_standby_state
-r--r--r-- 1 root root 4096 May 3 03:32 type
-rw-r--r-- 1 root root 4096 May 3 03:25 uevent

Answer 1

So, the final solution looks like this:
Step 1
Describe device in device tree, though you no need
kernel for handling it, but looks right to describe it here
gps-reciever {
compatible = "my_company_name,gps_recv_name";
vcc-supply = <&ext_gps_recv_reg>;
comment = "connected via usb<->rs232, port0";
};
where ext_gps_recv_reg of any normal regulator.
Step 2
I wrote a simple platform device driver for linux kernel,
that compatible with device above, and in probe function of this
driver I call platform_device_register_full that setup arguments for
userspace_consumer driver.
After that I can find suitable file via name:
cat /sys/bus/platform/devices/reg-userspace-consumer*/name,
and then disable/enable regulator via:
echo "disabled" > /sys/bus/platform/devices/reg-userspace-consumer*/state
So I separate device description from linux kernel implementation.