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      1 # Copyriht (c) 2014 The Chromium OS Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 
      5 import logging
      6 
      7 # Following Beaglebone GPIO pins are used to control the 8 port multiplexer.
      8 MUX_EN = '20'
      9 MUX_S0 = '115'
     10 MUX_S1 = '117'
     11 MUX_S2 = '49'
     12 
     13 ENABLE_MUX = '1'
     14 DISABLE_MUX = '0'
     15 
     16 # Various commands used to control the GPIO pins at the kernel level.
     17 LS_GPIO_DIRECTORY = 'ls /sys/class/gpio'
     18 EXPORT_GPIO_PIN = 'echo %s > /sys/class/gpio/export'
     19 SET_GPIO_DIRECTION = 'echo high > /sys/class/gpio/gpio%s/direction'
     20 SET_GPIO_VALUE = 'echo %s > /sys/class/gpio/gpio%s/value'
     21 UNEXPORT_GPIO_PIN = 'echo %s > /sys/class/gpio/unexport'
     22 
     23 # Values passed to each GPIO pin to enable a specific port.
     24 # Bit sequence: MUX_S2, MUX_S1, MUX_S0
     25 # Example: To enable port 5, MUX_S2 will be set to 1, MUX_S1 will be set to 0
     26 # and MUX_S0 will be set to 1
     27 ports = {0:'000', 1:'001', 2:'010', 3:'011', 4:'100', 5:'101', 6:'110', 7:'111'}
     28 
     29 class USBMuxController(object):
     30     """Class to control individual ports on a 8 port USB switch/hub.
     31 
     32     This class is responsible for enabling all the GPIO pins on the beaglebone
     33     needed to control the 8 port USB switch/hub. In order to use this USB mux
     34     controller you need custom hardware setup which connects to the beaglebone
     35     and drives the 8 port relay switch to turn the individual ports on the USB
     36     hub 'on'/'off'.
     37 
     38     TODO(harpreet) Write a USB mux hardware design document and provide a link
     39     here.
     40 
     41     """
     42 
     43     version = 1
     44 
     45     def __init__(self, host):
     46         """Initializes this USB Mux Controller instance.
     47 
     48         @param host: Host where the test will be run.
     49 
     50         """
     51         self.host = host
     52 
     53     def __del__(self):
     54         """Destructor of USBMuxController.
     55 
     56         Disables all GPIO pins used that control the multiplexer.
     57 
     58         """
     59         self.mux_teardown()
     60 
     61     def mux_setup(self):
     62         """
     63         Enable GPIO pins that control the multiplexer.
     64 
     65         """
     66         logging.info('Enable GPIO pins that control the multiplexer.')
     67         self.enable_gpio_pins(MUX_EN)
     68         self.disable_all_ports()
     69         self.enable_gpio_pins(MUX_S2)
     70         self.enable_gpio_pins(MUX_S1)
     71         self.enable_gpio_pins(MUX_S0)
     72 
     73     def mux_teardown(self):
     74         """
     75         Disable the multiplexer and unexport all GPIO pins.
     76 
     77         """
     78         logging.info('Start USB multiplexer teardown.')
     79         self.disable_all_ports()
     80         # unexport gpio pins
     81         logging.info('Unexport all GPIO pins.')
     82         self.host.servo.system(UNEXPORT_GPIO_PIN % MUX_S0)
     83         self.host.servo.system(UNEXPORT_GPIO_PIN % MUX_S1)
     84         self.host.servo.system(UNEXPORT_GPIO_PIN % MUX_S2)
     85         self.host.servo.system(UNEXPORT_GPIO_PIN % MUX_EN)
     86         logging.info('Completed USB multiplexer teardown. All USB ports should'
     87                      'now be turned off.')
     88 
     89     def enable_gpio_pins(self, pin):
     90         """
     91         Enables the given GPIO pin by exporting the pin and setting the
     92         direction.
     93 
     94         @param pin: GPIO pin to be enabled.
     95 
     96         """
     97         if 'gpio' + pin not in self.host.servo.system_output(LS_GPIO_DIRECTORY):
     98             self.host.servo.system(EXPORT_GPIO_PIN % pin)
     99             self.host.servo.system(SET_GPIO_DIRECTION % pin)
    100 
    101     def enable_port(self, usb_port):
    102         """
    103         Enables the given port on the USB hub.
    104 
    105         @param usb_port: USB port to be enabled.
    106 
    107         """
    108         port = ports[usb_port]
    109         logging.info('Enable port %s.', port)
    110         self.mux_setup()
    111         self.disable_all_ports()
    112 
    113         logging.info('Set GPIO pins to correct logic levels.')
    114         self.host.servo.system(SET_GPIO_VALUE % (port[0], MUX_S2))
    115         self.host.servo.system(SET_GPIO_VALUE % (port[1], MUX_S1))
    116         self.host.servo.system(SET_GPIO_VALUE % (port[2], MUX_S0))
    117 
    118         logging.info('Enable USB multiplexer. Appropriate port should now be'
    119                      'enabled')
    120         self.host.servo.system(SET_GPIO_VALUE % (ENABLE_MUX, MUX_EN))
    121 
    122     def disable_all_ports(self):
    123         """
    124         Disables all USB ports that are currently enabled.
    125 
    126         """
    127         if 'gpio20' in self.host.servo.system_output(LS_GPIO_DIRECTORY):
    128             logging.info('Disable USB ports.')
    129             self.host.servo.system(SET_GPIO_VALUE % (DISABLE_MUX, MUX_EN))
    130