Add a python example that works directly with the switchtec device

examples/temp_linux.py

@@ -0,0 +1,112 @@
+#!/usr/bin/env python3
+########################################################################
+##
+## Microsemi Switchtec(tm) PCIe Management Library
+## Copyright (c) 2017, Microsemi Corporation
+##
+## 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.
+##
+########################################################################
+
+# This code serves as a simple example for sending custom MRPC commands
+# with python by directly operating on the device. This script is exactly
+# the same as temp_lib.py but does not require the Switchtec library. Thus it's
+# a bit simpler and has fewer dependencies. However, as a consequence, it
+# will only work in Linux.
+#
+# I'd love to take a pull request for a full python library implementation!
+
+import os
+import sys
+import time
+import struct
+
+MRPC_ECHO = 65
+MRPC_DIETEMP = 4
+MRPC_DIETEMP_SET_MEAS = 1
+MRPC_DIETEMP_GET = 2
+
+class SwitchtecError(Exception):
+    pass
+
+class Switchtec(object):
+    def __init__(self, devpath):
+        self.fd = os.open(devpath, os.O_RDWR)
+
+    def cmd(self, cmd, indata=b"", outdata_len=0):
+        indata = struct.pack("<L", cmd) + indata
+        os.write(self.fd, indata)
+        outdata = os.read(self.fd, 4+outdata_len)
+
+        retcode = outdata[:4]
+        outdata = outdata[4:]
+
+        retcode, = struct.unpack("<L", retcode)
+
+        if retcode != 0:
+            raise SwitchtecError("Error occurred during command: {:x}".
+                                 format(retcode))
+
+        return outdata
+
+class CommandError(Exception):
+    pass
+
+def echo_cmd(dev):
+    my_cmd = struct.Struct("<LHHQ")
+
+    sub_cmd_in = 0xAA55
+    indata = my_cmd.pack(sub_cmd_in, 0x1234, 0x5678, int(time.time()))
+
+    outdata = dev.cmd(MRPC_ECHO, indata, len(indata))
+
+    sub_cmd_out, param1, param2, time_val = my_cmd.unpack(outdata)
+
+    if sub_cmd_in != ~sub_cmd_out & 0xFFFFFFFF:
+        raise CommandError("Echo data did not match: {:x} != ~{:x}".
+                           format(sub_cmd_in, sub_cmd_out))
+
+def die_temp(dev):
+    dev.cmd(MRPC_DIETEMP, struct.pack("<L", MRPC_DIETEMP_SET_MEAS))
+    temp_packed = dev.cmd(MRPC_DIETEMP, struct.pack("<L", MRPC_DIETEMP_GET), 4)
+
+    temp, = struct.unpack("<L", temp_packed)
+
+    print("Die Temp: {:.1f}°C".format(temp / 100.))
+
+if __name__ == "__main__":
+    import argparse
+    parser = argparse.ArgumentParser()
+    parser.add_argument("device", nargs="?", default="/dev/switchtec0",
+                        help="switchtec device to use")
+    options = parser.parse_args()
+
+    try:
+        dev = Switchtec(options.device)
+        echo_cmd(dev)
+        die_temp(dev)
+
+    except KeyboardInterrupt:
+        print()
+    except SwitchtecError as e:
+        print(e)
+    except CommandError as e:
+        print(e)
+    except OSError as e:
+        print(e)