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#
# Copyright 2017 Ettus Research (National Instruments)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
"""
Access to GPIOs mapped into the PS via sysfs
"""
import os
import pyudev
from .mpmlog import get_logger
GPIO_SYSFS_BASE_DIR = '/sys/class/gpio'
GPIO_SYSFS_LABELFILE = 'label'
GPIO_SYSFS_VALUEFILE = 'value'
def get_all_gpio_devs():
"""
Returns a list of all GPIO chips available through sysfs. Will look
something like ['gpiochip882', 'gpiochip123', ...]
"""
try:
context = pyudev.Context()
gpios = [device.sys_name.encode('ascii')
for device in context.list_devices(subsystem="gpio")
if os.path.exists(os.path.join( # udev probably has better ways to do this
GPIO_SYSFS_BASE_DIR,
device.sys_name.encode('ascii'),
GPIO_SYSFS_LABELFILE
))
]
return gpios
except OSError:
# Typically means GPIO not available, maybe no overlay
return []
def get_gpio_map_info(gpio_dev):
"""
Returns all the map info for a given GPIO device.
Example: If pio_dev is 'gpio882', it will list all files
in /sys/class/gpio/gpio882/ and create a dictionary with filenames
as keys and content as value. Subdirs are skipped.
Numbers are casted to numbers automatically. Strings remain strings.
"""
map_info = {}
map_info_path = os.path.join(
GPIO_SYSFS_BASE_DIR, gpio_dev,
)
for info_file in os.listdir(map_info_path):
if not os.path.isfile(os.path.join(map_info_path, info_file)):
continue
map_info_value = open(os.path.join(map_info_path, info_file), 'r').read().strip()
try:
map_info[info_file] = int(map_info_value, 0)
except ValueError:
map_info[info_file] = map_info_value
# Manually add GPIO number
context = pyudev.Context()
map_info['sys_number'] = int(
pyudev.Devices.from_name(context, subsystem="gpio", sys_name=gpio_dev).sys_number
)
return map_info
def find_gpio_device(label, logger=None):
"""
Given a label, returns a tuple (uio_device, map_info).
uio_device is something like 'gpio882'. map_info is a dictionary with
information regarding the GPIO device read from the map info sysfs dir.
"""
gpio_devices = get_all_gpio_devs()
if logger:
logger.trace("Found the following UIO devices: `{0}'".format(','.join(gpio_devices)))
for gpio_device in gpio_devices:
map_info = get_gpio_map_info(gpio_device)
if logger:
logger.trace("{0} has map info: {1}".format(gpio_device, map_info))
if map_info.get('label') == label:
if logger:
logger.trace("Device matches label: `{0}'".format(gpio_device))
return gpio_device, map_info
if logger:
logger.warning("Found no matching gpio device for label `{0}'".format(label))
return None, None
class SysFSGPIO(object):
"""
API for accessing GPIOs mapped into userland via sysfs
"""
def __init__(self, label, use_mask, ddr):
assert (use_mask & ddr) == ddr
self.log = get_logger("SysFSGPIO")
self._label = label
self._use_mask = use_mask
self._ddr = ddr
self.log.trace("Generating SysFSGPIO object for label `{}'...".format(label))
self._gpio_dev, self._map_info = find_gpio_device(label, self.log)
if self._gpio_dev is None:
self.log.error("Could not find GPIO device with label `{}'.".format(label))
self.log.trace("GPIO base number is {}".format(self._map_info.get("sys_number")))
self._base_gpio = self._map_info.get("sys_number")
self.init(self._map_info['ngpio'], self._base_gpio, self._use_mask, self._ddr)
def init(self, n_gpio, base, use_mask, ddr):
"""
Guarantees that all the devices are created accordingly
E.g., if use_mask & 0x1 is True, it makes sure that 'gpioXXX' is exported.
Also sets the DDRs.
"""
gpio_list = [x for x in xrange(n_gpio) if (1<<x) & use_mask]
self.log.trace("Initializing {} GPIOs...".format(len(gpio_list)))
for gpio_idx in gpio_list:
gpio_num = base + gpio_idx
ddr_out = ddr & (1<<gpio_idx)
gpio_path = os.path.join(GPIO_SYSFS_BASE_DIR, 'gpio{}'.format(gpio_num))
if not os.path.exists(gpio_path):
self.log.trace("Creating GPIO path `{}'...".format(gpio_path))
open(os.path.join(GPIO_SYSFS_BASE_DIR, 'export'), 'w').write('{}'.format(gpio_num))
ddr_str = 'out' if ddr_out else 'in'
self.log.trace("On GPIO path `{}', setting DDR mode to {}.".format(gpio_path, ddr_str))
open(os.path.join(GPIO_SYSFS_BASE_DIR, gpio_path, 'direction'), 'w').write(ddr_str)
def set(self, gpio_idx, value=None):
"""
Assert a GPIO at given index.
Note: The GPIO must be in the valid range, and it's DDR value must be
high (for "out").
"""
if value is None:
value = 1
assert (1<<gpio_idx) & self._use_mask
assert (1<<gpio_idx) & self._ddr
gpio_num = self._base_gpio + gpio_idx
gpio_path = os.path.join(GPIO_SYSFS_BASE_DIR, 'gpio{}'.format(gpio_num))
value_path = os.path.join(gpio_path, GPIO_SYSFS_VALUEFILE)
self.log.trace("Writing value `{}' to `{}'...".format(value, value_path))
assert os.path.exists(value_path)
open(value_path, 'w').write('{}'.format(value))
def reset(self, gpio_idx):
"""
Deassert a GPIO at given index.
Note: The GPIO must be in the valid range, and it's DDR value must be
high (for "out").
"""
self.set(gpio_idx, value=0)
def get(self, gpio_idx):
"""
Read back a GPIO at given index.
Note: The GPIO must be in the valid range, and it's DDR value must be
low (for "in").
"""
assert (1<<gpio_idx) & self._use_mask
assert (1<<gpio_idx) & (~self._ddr)
gpio_num = self._base_gpio + gpio_idx
gpio_path = os.path.join(GPIO_SYSFS_BASE_DIR, 'gpio{}'.format(gpio_num))
value_path = os.path.join(gpio_path, GPIO_SYSFS_VALUEFILE)
self.log.trace("Writing value from `{}'...".format(value_path))
assert os.path.exists(value_path)
return int(open(value_path, 'r').read().strip())
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