# Copyright (c) 2016 Robert Wolterman
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# CHIP_IO Utilities
# Random functions to enable fun stuff on the CHIP!

# Credit goes to nonokuono (https://bbs.nextthing.co/users/nonokunono)
# for gathering the i2cset commands from the AXP-209 datasheet for 2.0, 2.6, and 3.3V output
# and for figuring out the ADC setup on the AXP-209

import subprocess

# Set the 1.8V-pin on the CHIP U13-header to given voltage
# Return False on error
def set_1v8_pin_voltage(voltage):
    if not isinstance(voltage, int) and not isinstance(voltage, float):
        return False
    if voltage < 1.8 or voltage > 3.3:
        return False
    voltage=round((voltage - 1.8) / 0.1) << 4
    if subprocess.call(["/usr/sbin/i2cset", "-f", "-y" ,"0", "0x34", "0x90", "0x03"]):
        return False
    if subprocess.call(["/usr/sbin/i2cset", "-f", "-y", "0", "0x34", "0x91", str(voltage)]):
        return False
    return True

# Get the voltage the 1.8V-pin on the CHIP U13-header has been configured as
# Return False on error
def get_1v8_pin_voltage():
    p=subprocess.Popen(["/usr/sbin/i2cget", "-f", "-y", "0", "0x34", "0x90"], stdout=subprocess.PIPE)
    output=p.communicate()[0].decode("utf-8").strip()
    #Not configured as an output
    if output != "0x03":
        return False
    p=subprocess.Popen(["/usr/sbin/i2cget", "-f", "-y", "0", "0x34", "0x91"], stdout=subprocess.PIPE)
    output=p.communicate()[0].decode("utf-8").strip()
    voltage=round((int(output, 16) >> 4) * 0.1 + 1.8, 1)
    return voltage

# Enable 1.8V Pin on CHIP U13 Header
def enable_1v8_pin():
    set_1v8_pin_voltage(1.8)

# Disable 1.8V Pin on CHIP U13 Header
def disable_1v8_pin():
    # CANNOT USE I2C LIB AS WE NEED TO FORCE THE COMMAND DUE TO THE KERNEL OWNING THE DEVICE
    # First we have to write 0x05 to AXP-209 Register 0x91
    subprocess.call('/usr/sbin/i2cset -f -y 0 0x34 0x91 0x05', shell=True)
    # Then we have to write 0x07 to AXP-209 Register 0x90
    subprocess.call('/usr/sbin/i2cset -f -y 0 0x34 0x90 0x07', shell=True)