snagrecover: am335x: drop UART recovery

An overwhelming majority of ARM SoC recovery flows rely on USB. Among the
recovery flows currently supported by snagboot, the only exception is AM335x
UART recovery, which is drastically slower than AM335x USB recovery.

In the interest of improving the coherency and efficiency of Snagboot as a USB
recovery and flashing tool, drop AM335x UART recovery.

Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>

docs/board_setup.md

@@ -6,12 +6,11 @@ boot fuses, removing some external boot media and/or other board-specific
 actions. Referring to your board's user guide can help you find out
 what you need to do here.
 
-The board should be connected to your host PC via USB (except for the special
-case of AM335x UART recovery). The specific USB port to use is board-dependent,
-it is usually the OTG port. We also strongly recommend that you open a UART
-connection to the board so that you can monitor the recovery process as it
-unfolds. On STM32MP1 discovery kits, the default UART is often wired to the
-ST-LINK port.
+The board should be connected to your host PC via USB The specific USB port to
+use is board-dependent, it is usually the OTG port. We also strongly recommend
+that you open a UART connection to the board so that you can monitor the
+recovery process as it unfolds. On STM32MP1 discovery kits, the default UART is
+often wired to the ST-LINK port.
 
 Once your board is in recovery mode, a new USB device should appear on your host
 system. This is the device that snagrecover will communicate with. Below are
@@ -62,24 +61,7 @@ During initialization, the ROM code will set up a boot device list and for each
 device, will try to perform either a memory boot or a peripheral boot.
 Peripheral booting is what interests us for recovering a board. It can be done
 over USB, UART or Ethernet. Out of the 3 possible peripheral boot modes,
-snagrecover supports UART mode, and USB mode.  UART is much simpler to setup but
-is very slow and for this reason is only supported by snagrecover, not
-snagflash.
-
-### TI AM335x UART recovery
-
-Connect a UART to the board, open a serial port and make sure that the ROM code
-boots in UART mode. If that’s the case, it should regularly ping the serial
-console which will result in the character “C” being displayed.
-
-As an example, here is the procedure for the Beaglebone black wireless board :
-
-1. remove all connectors and make sure that the sd card slot is empty
-2. set up the UART cable on the serial header (GND:J1 RX: J4 TX: J5).
-3. hold the S2 button and plug the power cable in. This will change the boot
-	sequence so that the board doesn’t try to boot from eMMC.
-4. open a serial port and press the reset button. You should get pings in your
-	console
+snagrecover only supports USB mode.
 
 ### TI AM335x USB recovery
 

docs/fw_binaries.md

@@ -179,10 +179,9 @@ configuration:
 
 [example](../src/snagrecover/templates/am335x-beaglebone-black.yaml)
 
-**spl:** First stage bootloader. Build the spl/u-boot-spl.bin target for your
-board in U-Boot mainline. If recovering via UART, SPL should be built with
-CONFIG\_SPL\_YMODEM_SUPPORT enabled. If recovering via USB, the USB Ethernet
-gadget should be enabled, which implies the following options:
+**spl:** First stage bootloader. Build the spl/u-boot-spl.bin target for your board in U-Boot
+mainline. If recovering via USB, the USB Ethernet gadget should be enabled, which implies the
+following options:
 
 ```bash
 CONFIG\_SPL\_NET\_SUPPORT=y

docs/snagrecover.md

@@ -24,10 +24,6 @@ USB device can be found in sysfs :
 
 `/sys/bus/usb/devices/...`.
 
-When recovering an AM335x SOC via UART using the snagrecover, you have to pass
-the --uart flag to the CLI. You can also pass the --baudrate flag in case the
-default 115200 baud rate does not fit your device.
-
 The rest of the command line arguments are optional.
 
 Examples:

docs/troubleshooting.md

@@ -28,15 +28,3 @@ binaries](fw_binaries.md) section of the docs.
 On some boards, you have to enable `CONFIG_USB_ETHER` in U-Boot for USB gadgets
 to work correctly.
 
-## AM335x UART recovery fails after running SPL
-
-In some cases SPL's standard console output can be confused with xmodem 'C'
-pings. You can set the following U-Boot configuration options to try and silence
-SPL:
-
-```
-CONFIG_SPL_SILENT_CONSOLE=y
-CONFIG_SPL_BANNER_PRINT=n
-CONFIG_SPL_DISPLAY_PRINT=n
-```
-

pyproject.toml

@@ -30,7 +30,6 @@ dependencies = [
 	"pyyaml >= 6.0",
 	"pyusb >= 1.2.1",
 	"pyserial >= 3.5",
-	"xmodem >= 0.4.6",
 	"tftpy >= 0.8.2",
 	"crccheck >= 1.3.0",
 	"pylibfdt >= 1.7.0.post1",

src/snagrecover/cli.py

@@ -47,8 +47,6 @@ def cli():
 	mandatory.add_argument("-f", "--firmware-file", help="firmware configurations, passed as a yaml file", metavar="\"templates/colibri-imx7d.yaml\"", action="append")
 	mandatory.add_argument("-F", "--firmware", help="firmware configurations, formatted as a python3 dict", metavar="\"{'fw1': {'path': '/path/to', 'address': 0x00}}\"", action="append", type=ast.literal_eval)
 	optional = parser.add_argument_group("Optional")
-	optional.add_argument("--uart", help="use UART for AM335x recovery", metavar="/dev/ttyx")
-	optional.add_argument("--baudrate", help="UART baudrate", default=115200)
 	optional.add_argument("--netns", help="network namespace for AM335x USB recovery, defaults to 'snagbootnet'", default="snagbootnet")
 	optional.add_argument("--loglevel", help="set loglevel", choices=["silent","info","debug"], default="silent")
 	optional.add_argument("--logfile", help="set logfile", default="board_recovery.log")

src/snagrecover/firmware/am335x_fw.py

@@ -24,16 +24,9 @@
 import time
 import logging
 logger = logging.getLogger("snagrecover")
-from xmodem import XMODEM
-# setting this logger to the same format as the main
-# logger since it sometimes prints out messages that seem
-# like fatal errors but are apparently benign
-xmodem_logger = logging.getLogger("xmodem.XMODEM")
-xmodem_logger.parent = logger
 import tftpy
 import threading
 import os.path
-import collections
 import errno
 
 server_config = {
@@ -87,7 +80,7 @@ def handle(self):
 			else:
 				raise err
 
-def am335x_usb(port, fw_name: str):
+def am335x_run(port, fw_name: str):
 	tftp_start_timeout = server_config["tftp_start_timeout"]
 	tftp_complete_timeout = server_config["tftp_complete_timeout"]
 	# TFTP server thread
@@ -134,55 +127,3 @@ def am335x_usb(port, fw_name: str):
 	print("Waiting for TFTP shutdown...")
 	tftp_thread.join()
 
-xmodem_total_size = 0
-def xmodem_callback(total_packets: int, success_count: int, error_count: int):
-	"""
-	This is called during the xmodem transfer,
-	it prints a progress bar
-	"""
-	global xmodem_total_size
-	progress = int(100 * total_packets * 1.0 / xmodem_total_size)
-	print(f"\rprogress: {progress}%", end="")
-
-
-def am335x_uart(port, fw_name: str):
-	TRANSFER_WAIT_TIMEOUT = 30
-	global xmodem_total_size
-	if fw_name == "u-boot":
-		print("Transfering U-Boot over a UART connection, this could take a while...")
-	port.write_timeout = 5
-	port.timeout = 5
-
-	def getc(size, timeout=1):
-		return port.read(size) or None
-
-	def putc(data, timeout=1):
-		return port.write(data)
-
-	modem = XMODEM(getc, putc)
-	"""
-	snagrecover sometimes confuses standard SPL console output
-	with xmodem pings (see issue #14), we wait for three pings
-	to reduce the likelihood of this happening
-	"""
-	print("Waiting for three pings before xmodem transfer...")
-	ping_buf = collections.deque(maxlen=3)
-	t0 = time.time()
-	while list(ping_buf) != [b"C", b"C", b"C"]:
-		ping_buf.append(port.read(1))
-		if time.time() - t0 > TRANSFER_WAIT_TIMEOUT:
-			raise Exception("Timeout waiting for UART pings")
-	fw_path = recovery_config["firmware"][fw_name]["path"]
-	xmodem_total_size = int(os.path.getsize(fw_path) / 128)
-	with open(fw_path, "rb") as file:
-		logger.info(f"Transfering {fw_path} using xmodem...")
-		modem.send(file, callback=xmodem_callback)
-		print("")
-	logger.info("xmodem transfer done")
-
-def am335x_run(port, fw_name: str):
-	if recovery_config["args"]["uart"]:
-		am335x_uart(port, fw_name)
-	else:
-		am335x_usb(port, fw_name)
-

src/snagrecover/recoveries/am335x.py

@@ -17,31 +17,24 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
-import serial
 from snagrecover.config import recovery_config
 from snagrecover.firmware.firmware import run_firmware
 import subprocess
 import os
 import sys
 
 def main():
-	if recovery_config["args"]["uart"]:
-		port = serial.Serial(recovery_config["args"]["uart"], baudrate=recovery_config["args"]["baudrate"])
-		run_firmware(port, "spl")
-		run_firmware(port, "u-boot")
-		port.close()
-	else:
-		# Check that we are running in the expected network namespace
-		netns_name = recovery_config["args"]["netns"]
-		bash_cmd = "ip netns identify " + str(os.getpid())
-		process = subprocess.Popen(bash_cmd.split(), stdout=subprocess.PIPE)
-		output, error = process.communicate()
-		if output.decode("ascii") != f"{netns_name}\n":
-			print(f"This recovery needs to be run in the {netns_name} namespace!\nDid you run sudo am335x_usb_setup.sh?", file=sys.stderr)
-			sys.exit(-1)
+	# Check that we are running in the expected network namespace
+	netns_name = recovery_config["args"]["netns"]
+	bash_cmd = "ip netns identify " + str(os.getpid())
+	process = subprocess.Popen(bash_cmd.split(), stdout=subprocess.PIPE)
+	output, error = process.communicate()
+	if output.decode("ascii") != f"{netns_name}\n":
+		print(f"This recovery needs to be run in the {netns_name} namespace!\nDid you run sudo am335x_usb_setup.sh?", file=sys.stderr)
+		sys.exit(-1)
 
-		# Install and run SPL
-		run_firmware(None, "spl")
-		# Install and run U-Boot
-		run_firmware(None, "u-boot")
+	# Install and run SPL
+	run_firmware(None, "spl")
+	# Install and run U-Boot
+	run_firmware(None, "u-boot")