ci/bare-metal: Use python for handling fastboot booting and parsing

Modeling after what I did for cros_servo_run.py, this gives us easy
support for restarting the test run a530 when we detect a spontaneous
reboot.  I had to touch up serial_buffer.py to handle buffering in from a
file instead of a serial device, to support the upcoming etnaviv CI
(tested by running it against a serial log from db410c and seeing it step
to calling "fastboot")

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6529>
diff --git a/.gitlab-ci/bare-metal/fastboot.sh b/.gitlab-ci/bare-metal/fastboot.sh
index 81d9476..3a6d1f1 100755
--- a/.gitlab-ci/bare-metal/fastboot.sh
+++ b/.gitlab-ci/bare-metal/fastboot.sh
@@ -57,7 +57,6 @@
 # Clear out any previous run's artifacts.
 rm -rf results/
 mkdir -p results
-find artifacts/ -name serial\*.txt  | xargs rm -f
 
 # Create the rootfs in a temp dir
 rsync -a --delete $BM_ROOTFS/ rootfs/
@@ -90,41 +89,19 @@
   nginx
 fi
 
-# Start watching serial, and power up the device.
-if [ -n "$BM_SERIAL" ]; then
-  python3 $BM/serial_buffer.py \
-    --dev $BM_SERIAL \
-    --file artifacts/serial-output.txt \
-    --prefix "SERIAL> " &
-else
-  PATH=$BM:$PATH $BM_SERIAL_SCRIPT | tee artifacts/serial-output.txt &
+export PATH=$BM:$PATH
+
+# Start background command for talking to serial if we have one.
+if [ -n "$BM_SERIAL_SCRIPT" ]; then
+  $BM_SERIAL_SCRIPT | tee results/serial-output.txt &
+
+  while [ ! -e results/serial-output.txt ]; do
+    sleep 1
+  done
 fi
 
-while [ ! -e artifacts/serial-output.txt ]; do
-  sleep 1
-done
-PATH=$BM:$PATH $BM_POWERUP
-
-# Once fastboot is ready, boot our image.
-$BM/expect-output.sh artifacts/serial-output.txt \
-  -f "fastboot: processing commands" \
-  -f "Listening for fastboot command on" \
-  -e "data abort"
-
-fastboot boot -s $BM_FASTBOOT_SERIAL artifacts/fastboot.img
-
-# Wait for the device to complete the deqp run
-$BM/expect-output.sh artifacts/serial-output.txt \
-    -f "bare-metal result" \
-    -e "---. end Kernel panic"
-
-# power down the device
-PATH=$BM:$PATH $BM_POWERDOWN
-
-set +e
-if grep -q "bare-metal result: pass" artifacts/serial-output.txt; then
-   exit 0
-else
-   exit 1
-fi
-
+$BM/fastboot_run.py \
+  --dev="$BM_SERIAL" \
+  --fbserial="$BM_FASTBOOT_SERIAL" \
+  --powerup="$BM_POWERUP" \
+  --powerdown="$BM_POWERDOWN"
diff --git a/.gitlab-ci/bare-metal/fastboot_run.py b/.gitlab-ci/bare-metal/fastboot_run.py
new file mode 100755
index 0000000..6f28653
--- /dev/null
+++ b/.gitlab-ci/bare-metal/fastboot_run.py
@@ -0,0 +1,102 @@
+#!/usr/bin/env python3
+#
+# Copyright © 2020 Google LLC
+#
+# 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 (including the next
+# paragraph) 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.
+
+import argparse
+import os
+import re
+from serial_buffer import SerialBuffer
+import sys
+import threading
+
+class FastbootRun:
+    def __init__(self, args):
+        self.powerup = args.powerup
+        self.ser = SerialBuffer(args.dev, "results/serial-output.txt", "R SERIAL> ")
+        self.fastboot="fastboot boot -s {ser} artifacts/fastboot.img".format(ser=args.fbserial)
+
+    def logged_system(self, cmd):
+        print("Running '{}'".format(cmd))
+        return os.system(cmd)
+
+    def run(self):
+        if self.logged_system(self.powerup) != 0:
+            return 1
+
+        fastboot_ready = False
+        for line in self.ser.lines():
+            if re.search("fastboot: processing commands", line) or \
+                re.search("Listening for fastboot command on", line):
+                fastboot_ready = True
+                break
+
+            if re.search("data abort", line):
+                return 1
+
+        if not fastboot_ready:
+            print("Failed to get to fastboot prompt")
+            return 1
+
+        if self.logged_system(self.fastboot) != 0:
+            return 1
+
+        for line in self.ser.lines():
+            if re.search("---. end Kernel panic", line):
+                return 1
+
+            # The db820c boards intermittently reboot.  Just restart the run
+            # when if we see a reboot after we got past fastboot.
+            if re.search("PON REASON", line):
+                print("Detected spontaneous reboot, restarting run...")
+                return 2
+
+            result = re.search("bare-metal result: (\S*)", line)
+            if result:
+                if result.group(1) == "pass":
+                    return 0
+                else:
+                    return 1
+
+        print("Reached the end of the CPU serial log without finding a result")
+        return 1
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--dev', type=str, help='Serial device (otherwise reading from serial-output.txt)')
+    parser.add_argument('--powerup', type=str, help='shell command for rebooting', required=True)
+    parser.add_argument('--powerdown', type=str, help='shell command for powering off', required=True)
+    parser.add_argument('--fbserial', type=str, help='fastboot serial number of the board', required=True)
+    args = parser.parse_args()
+
+    fastboot = FastbootRun(args)
+
+    while True:
+        retval = fastboot.run()
+        if retval != 2:
+            break
+
+    fastboot.logged_system(args.powerdown)
+
+    sys.exit(retval)
+
+if __name__ == '__main__':
+    main()
diff --git a/.gitlab-ci/bare-metal/serial_buffer.py b/.gitlab-ci/bare-metal/serial_buffer.py
index 886bce6..d461721 100755
--- a/.gitlab-ci/bare-metal/serial_buffer.py
+++ b/.gitlab-ci/bare-metal/serial_buffer.py
@@ -26,19 +26,30 @@
 import queue
 import serial
 import threading
+import time
 
 class SerialBuffer:
     def __init__(self, dev, filename, prefix):
-        self.f = open(filename, "wb+")
+        self.filename = filename
         self.dev = dev
-        self.serial = serial.Serial(dev, 115200, timeout=10)
+
+        if dev:
+            self.f = open(filename, "wb+")
+            self.serial = serial.Serial(dev, 115200, timeout=10)
+        else:
+            self.f = open(filename, "rb")
+
         self.byte_queue = queue.Queue()
         self.line_queue = queue.Queue()
         self.prefix = prefix
         self.sentinel = object()
 
-        self.read_thread = threading.Thread(target=self.serial_read_thread_loop, daemon=True)
+        if self.dev:
+            self.read_thread = threading.Thread(target=self.serial_read_thread_loop, daemon=True)
+        else:
+            self.read_thread = threading.Thread(target=self.serial_file_read_thread_loop, daemon=True)
         self.read_thread.start()
+
         self.lines_thread = threading.Thread(target=self.serial_lines_thread_loop, daemon=True)
         self.lines_thread.start()
 
@@ -56,6 +67,19 @@
                 self.byte_queue.put(self.sentinel)
                 break
 
+    # Thread that just reads the bytes from the file of serial output that some
+    # other process is appending to.
+    def serial_file_read_thread_loop(self):
+        greet = "Serial thread reading from %s\n" % self.filename
+        self.byte_queue.put(greet.encode())
+
+        while True:
+            line = self.f.readline()
+            if line:
+                self.byte_queue.put(line)
+            else:
+                time.sleep(0.1)
+
     # Thread that processes the stream of bytes to 1) log to stdout, 2) log to
     # file, 3) add to the queue of lines to be read by program logic
 
@@ -69,9 +93,11 @@
                 self.line_queue.put(self.sentinel)
                 break;
 
-            # Write our data to the output file
-            self.f.write(bytes)
-            self.f.flush()
+            # Write our data to the output file if we're the ones reading from
+            # the serial device
+            if self.dev:
+                self.f.write(bytes)
+                self.f.flush()
 
             for b in bytes:
                 line.append(b)
@@ -96,8 +122,8 @@
 def main():
     parser = argparse.ArgumentParser()
 
-    parser.add_argument('--dev', type=str, help='Serial device', required=True)
-    parser.add_argument('--file', type=str, help='Filename to output our serial data to')
+    parser.add_argument('--dev', type=str, help='Serial device')
+    parser.add_argument('--file', type=str, help='Filename for serial output', required=True)
     parser.add_argument('--prefix', type=str, help='Prefix for logging serial to stdout', nargs='?')
 
     args = parser.parse_args()