# # Copyright 2017 Ettus Research, a National Instruments Company # # SPDX-License-Identifier: GPL-3.0-or-later # """ Access to UIO mapped memory. """ import os from contextlib import contextmanager from builtins import object import pyudev import usrp_mpm.libpyusrp_periphs as lib from usrp_mpm.mpmlog import get_logger UIO_SYSFS_BASE_DIR = '/sys/class/uio' UIO_DEV_BASE_DIR = '/dev' @contextmanager def open_uio(label=None, path=None, length=None, read_only=True, offset=None): """Convenience function for creating a UIO object. Use this like you would open() for a file""" uio_obj = UIO(label, path, length, read_only, offset) uio_obj._open() yield uio_obj uio_obj._close() def get_all_uio_devs(): """ Return a list of all uio devices. Will look something like ['uio0', 'uio1', ...]. """ try: context = pyudev.Context() paths = [os.path.split(device.device_node)[-1] for device in context.list_devices(subsystem="uio")] return paths except OSError: # Typically means UIO devices return [] def get_uio_map_info(uio_dev, map_num): """ Returns all the map info for a given UIO device and map number. Example: If uio_dev is 'uio0', and map_num is 0, it will list all files in /sys/class/uio/uio0/maps/map0/ and create a dictionary with filenames as keys and content as value. Numbers are casted to numbers automatically. Strings remain strings. """ map_info = {} map_info_path = os.path.join( UIO_SYSFS_BASE_DIR, uio_dev, 'maps', 'map{0}'.format(map_num) ) for info_file in os.listdir(map_info_path): 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 return map_info def find_uio_device(label, logger=None): """ Given a label, returns a tuple (uio_device, map_info). uio_device is something like '/dev/uio0'. map_info is a dictionary with information regarding the UIO device read from the map info sysfs dir. Note: We assume a single map (map0) for all UIO devices here. """ uio_devices = get_all_uio_devs() if logger: logger.trace("Found the following UIO devices: `{0}'".format(','.join(uio_devices))) for uio_device in uio_devices: map0_info = get_uio_map_info(uio_device, 0) if logger: logger.trace("{0} has map info: {1}".format(uio_device, map0_info)) if map0_info.get('name') == label: if logger: logger.trace("Device matches label: `{0}'".format(uio_device)) return os.path.join(UIO_DEV_BASE_DIR, uio_device), map0_info if logger: logger.warning("Found no matching UIO device for label `{0}'".format(label)) return None, None class UIO(object): """ Provides peek/poke interfaces for uio-mapped memory. This object will not, by default, open the associated UIO device. To actually open the device, you have two options: - Use the instantiation of this class as a context manager (using a `with` statement), like this: >>> uio0 = UIO(path="/dev/uio0"): >>> with uio0: >>> uio0.peek32(addr) >>> uio0.poke32(addr, value) Or like this: >>> with UIO(path="/dev/uio0") as uio0: >>> uio0.peek32(addr) >>> uio0.poke32(addr, value) - This is Highly Discouraged, but if you need to, manually call _open() and _close(): >>> uio0 = UIO(path="/dev/uio0") >>> uio0._open() >>> uio0.peek32(addr) >>> uio0.poke32(addr, value) >>> uio0._close() Arguments: label -- Label of the UIO device. The label is set in the device tree overlay path -- Path to UIO device, e.g. '/dev/uio0'. This is ignored if 'label' is provided. length -- Number of bytes in the address space (is passed to mmap.mmap). This is usually automatically determined. No need to set it. Unless you really know what you're doing. read_only -- Boolean; True == ro, False == rw offset -- Passed to mmap.mmap. This is usually automatically determined. No need to set it. Unless you really know what you're doing. """ def __init__(self, label=None, path=None, length=None, read_only=True, offset=None): self.log = get_logger('UIO') if label is None: self._path = path self.log.trace("Using UIO device `{0}'".format(path)) uio_device = os.path.split(path)[-1] self.log.trace("Getting map info for UIO device `{0}'".format(uio_device)) map_info = get_uio_map_info(uio_device, 0) # Python can't tell the size of a uio device by itself assert length is not None else: self.log.trace("Using UIO device by label `{0}'".format(label)) self._path, map_info = find_uio_device(label, self.log) # TODO If we ever support multiple maps, check if this is correct... offset = offset or map_info['offset'] assert offset == 0 # ...and then remove this line length = length or map_info['size'] self.log.trace("UIO device is being opened read-{0}.".format( "only" if read_only else "write")) if self._path is None: self.log.error("Could not find a UIO device for label {0}".format(label)) raise RuntimeError("Could not find a UIO device for label {0}".format(label)) self._read_only = read_only # Our UIO objects are managed in C++ land, which gives us more granular control over # opening and closing self._uio = lib.types.mmap_regs_iface(self._path, length, offset, self._read_only, False) # Reference counter for safely __enter__ and __exit__-ing self._ref_count = 0 def __enter__(self): return self._open() def __exit__(self, exc_type, exc_value, traceback): self._close() return exc_type is None def _open(self): """Actually open the UIO device. You need to call this before doing peeks and pokes. See also close(). If you're using the UIO object as a context manager, it will open the file automatically. """ if self._ref_count == 0: self._uio.open() self._ref_count += 1 return self def _close(self): """Close a UIO device. UIO devices can be problematic with regards to file descriptor leakage, so it is recommended to close a UIO device when it is no longer needed. """ self._ref_count -= 1 if self._ref_count == 0: self._uio.close() def peek32(self, addr): """ Returns the 32-bit value starting at address addr as an integer """ return self._uio.peek32(addr) def poke32(self, addr, val): """ Writes the 32-bit value val to address starting at addr. Will throw if read_only was set to True. A value that exceeds 32 bits will be truncated to 32 bits. """ assert not self._read_only return self._uio.poke32(addr, val)