eg25-control: support power-on/off via GPIO control instead of modem-power

pkgs/additional/eg25-control/eg25-control

@@ -1,5 +1,6 @@
 #!/usr/bin/env nix-shell
-#!nix-shell -i python3 -p curl -p modemmanager-split.mmcli -p python3
+#!nix-shell -i python3 -p curl -p modemmanager-split.mmcli -p python3 -p python3.pkgs.libgpiod
+# vim: set filetype=python :
 
 # this script should run after ModemManager.service is started.
 # typical invocation is `eg25-control --power-on --enable-gps`.
@@ -56,10 +57,14 @@
 # - Galileo (EU)
 # - BeiDou (CN)
 # ^ these are all global systems, usable outside the country that owns them
+#
+# eg25 modem/power docs
+# [EG25-HW]: https://wiki.pine64.org/images/2/20/Quectel_EG25-G_Hardware_Design_V1.4.pdf
 
 
 import argparse
 import datetime
+import gpiod
 import logging
 import os
 import subprocess
@@ -289,6 +294,8 @@ class Phy:
         raise NotImplementedError()
     def power_off(self) -> None:
         raise NotImplementedError()
+    def dump_debug_info(self) -> None:
+        pass
 
 class MegiPhy(Phy):
     """
@@ -304,6 +311,96 @@ class MegiPhy(Phy):
     def power_off(self) -> None:
         self.executor.write_file(self.power_endpoint, b'0')
 
+class GpioPhy:
+    # power-on/off sequence documented in a few places:
+    # - EG25-HW 3.7
+    # - <https://lupyuen.github.io/articles/lte>
+    # - modem-power.c in megi's kernel tree
+    # - eg25-manager source code
+    #
+    # PLEASE NOTE THAT THIS REQUIRES THE AXP REGULATOR TO BE POWERING VBAT-BB.
+    # as of 2024-09-19, that's not mainline; it still requires a handful of patches.
+    # see postmarketOS' or mobian's kernel to cherry-pick the necessary patches.
+
+    # GPIO indices ("lines")
+    # DTR = "Data Terminal Ready", controls sleep/wakeup. high means modem is allowed to sleep when requested. high -> low forces the modem awake. internal pull-up.
+    # WAKEUP = 6
+    DTR = 34  # PB2
+    PWRKEY = 35  # PB3
+    RESET = 68  # PC4
+    APREADY = 231  # PH7, a.k.a. "host ready"
+    DISABLE = 232  # PH8, a.k.a. "enable"; active-low
+    # STATUS line: HIGH means powered off
+    STATUS = 233  # PH9
+    def __init__(self):
+        self.lines = gpiod.request_lines(
+            "/dev/gpiochip1",
+            consumer="eg25-control",
+            config={
+               GpioPhy.DTR: gpiod.LineSettings(direction=gpiod.line.Direction.OUTPUT),
+               GpioPhy.PWRKEY: gpiod.LineSettings(direction=gpiod.line.Direction.OUTPUT),
+               GpioPhy.RESET: gpiod.LineSettings(direction=gpiod.line.Direction.OUTPUT),
+               GpioPhy.APREADY: gpiod.LineSettings(direction=gpiod.line.Direction.OUTPUT),
+               GpioPhy.DISABLE: gpiod.LineSettings(direction=gpiod.line.Direction.OUTPUT),
+               GpioPhy.STATUS: gpiod.LineSettings(direction=gpiod.line.Direction.INPUT, bias=gpiod.line.Bias.PULL_UP),
+            },
+        )
+
+    def power_toggle(self, disable = gpiod.line.Value.INACTIVE) -> None:
+        # power-on is signalled by toggling the PWRKEY, and the modem interprets that as either a power-up OR a power-down request.
+        self.dump_debug_info()
+
+        if self.lines.get_value(self.STATUS) == disable:
+            # i wouldn't be surprised if the modem can get "stuck" in some state such that this early return always hits,
+            # if that's the case add some `--force` flag or verify against `mmcli -m any` report, etc.
+            logger.info("modem appears physically to already be in the desired state: not changing")
+            return
+
+        self.lines.set_value(self.APREADY, gpiod.line.Value.ACTIVE)
+        self.lines.set_value(self.DISABLE, disable)
+        self.lines.set_value(self.RESET, gpiod.line.Value.INACTIVE)
+        self.lines.set_value(self.PWRKEY, gpiod.line.Value.INACTIVE)
+        self.lines.set_value(self.DTR, gpiod.line.Value.INACTIVE)
+
+        # Megi's modem-power sleeps 50ms, cites datasheet claim to 30ms power-on
+        time.sleep(0.050)
+
+        self.dump_debug_info()
+
+        self.lines.set_value(self.PWRKEY, gpiod.line.Value.ACTIVE)
+        # Megi's modem-power sleeps 200ms; eg25-manager sleeps 1.0s; EG25-HW 3.7 says 500ms+ for power-on, 650ms+ for power-off
+        time.sleep(1.0)
+        self.lines.set_value(self.PWRKEY, gpiod.line.Value.INACTIVE)
+
+        # TODO: switch 'status' key to input (megi's modem-power claims it can be multiplexed with other stuff, so shouldn't be actively driven when possible)
+        for i in range(10):
+            self.dump_debug_info()
+            if self.lines.get_value(self.STATUS) == disable:
+                break
+            else:
+                logger.info("modem hasn't pulled STATUS low: sleeping for 1s")
+                time.sleep(1.0)
+        else:
+            logger.info("modem didn't pull STATUS low after 10s: giving up and continuing")
+
+    def power_on(self) -> None:
+        self.power_toggle()
+
+    def power_off(self) -> None:
+        self.power_toggle(disable=gpiod.line.Value.ACTIVE)
+
+    def dump_debug_info(self) -> None:
+        vals = self.lines.get_values()
+        dtr, pwrkey, reset, apready, disable, status = vals
+        logger.debug(
+            "gpio states:\n"
+            f"  DTR: {dtr}\n"
+            f"  PWRKEY: {pwrkey}\n"
+            f"  RESET: {reset}\n"
+            f"  APREADY: {apready}\n"
+            f"  DISABLE: {disable}\n"
+            f"  STATUS: {status}"
+        )
 
 class Sequencer:
     def __init__(self, executor: Executor, modem: str, modem_phy: Phy, state_fs: Filesystem):
@@ -464,6 +561,7 @@ class Sequencer:
         assert 'EG25GGBR07A08M2G' in hw or self.executor.dry_run, hw
 
     def dump_debug_info(self) -> None:
+        self.modem_phy.dump_debug_info()
         logger.debug('checking if AGPS is enabled (1) or not (0)')
         self._at_structured_cmd('QGPSXTRA?')
         # see if the GPS assistance data is still within valid range
@@ -581,8 +679,8 @@ def main():
     logging.getLogger().setLevel(logging.INFO)
 
     parser = argparse.ArgumentParser(description="initialize the eg25 Pinephone modem for GPS tracking")
-    parser.add_argument('--modem', default='any', help='name of modem to configure (see mmcli --list-modems)')
-    parser.add_argument('--power-endpoint', default='/sys/class/modem-power/modem-power/device/powered', help='sysfs endpoint that can turn the modem on/off')
+    parser.add_argument('--modem', default='any', help="name of modem to configure (see mmcli --list-modems)")
+    parser.add_argument('--power-endpoint', default='', help="sysfs endpoint that can turn the modem on/off (if using megi's modem-power), e.g. /sys/class/modem-power/modem-power/device/powered")
     parser.add_argument('--state-dir', default='')
 
     parser.add_argument("--dry-run", action='store_true', help="print commands instead of executing them")
@@ -608,7 +706,15 @@ def main():
 
     executor = Executor(dry_run=args.dry_run)
     state_fs = Filesystem(executor, root=state_dir)
-    sequencer = Sequencer(executor, modem=args.modem, modem_phy=MegiPhy(executor, args.power_endpoint), state_fs=state_fs)
+
+    modem_phy = Phy()
+    if args.power_endpoint:
+        modem_phy = MegiPhy(executor, args.power_endpoint)
+    elif args.power_on or args.power_off:
+        # don't initialize the Gpio PHY unless absolutely necessary, since it has to (re-)configure GPIOs just to show debug info
+        modem_phy = GpioPhy()
+
+    sequencer = Sequencer(executor, modem=args.modem, modem_phy=modem_phy, state_fs=state_fs)
 
     if args.power_on:
         sequencer.power_on()