#!/bin/sh
# Reset the ath10k wifi module on gfrg2x0 devices.  Separating out the
# two PCIe reset lines is tricky, so we end up also resetting ath9k
# module, which sucks, but this should never happen anyway except when
# there's a wifi firmware crash, in which case all bets are off anyway.
#
# Note: rather than reloading drivers, it would be nice to do something
# like:
#   echo 1 >/sys/bus/pci/devices/0000:00:00.0/remove
#   echo 1 >/sys/bus/pci/devices/0000:01:00.0/remove
#   ...reset PCIe bus...
#   echo 1 >/sys/bus/pci/rescan
# Unfortunately, this doesn't work correctly.  In the kernel, in
# pcie-c2000.c, it tries to use pci_save_state() and pci_restore_state()
# on all devices to make sure their PCI configuration registers aren't
# lost across the bus reset.  But if we unregister the PCI devices,
# there is nothing to pci_save_state() on, and so the values are lost.
# When we subsequently rescan, we get default PCI configuration values,
# including a missing IRQ line.  That's probably fixable, but this works
# too.  As a bonus, it guarantees the ath9k module is always detected
# before the ath10k module, which is how it works at bootup, so the
# interface names should end up being the same as at boot.

# This doesn't depend on anything in the environment.
echo "ath10k-reset: starting." >/dev/kmsg
exec >/dev/kmsg 2>&1

# Usually called straight from a kernel thread, so environment is empty.
export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

{
  echo "removing drivers..." >&2
  pkill -9 hostapd
  for m in ath10k_pci ath9k; do
    while [ -e "/sys/module/$m" ]; do
      echo "removing module '$m'..." >&2
      rmmod "$m" || { echo "failed to remove '$m'" >&2; exit 1; }
    done
  done
  echo "resetting PCIe buses..." >&2 &&
  echo 1 >/sys/devices/platform/pcie.0/device_reset &&
  echo 1 >/sys/devices/platform/pcie.1/device_reset &&
  echo 0 >/sys/devices/platform/pcie.0/device_reset &&
  echo 0 >/sys/devices/platform/pcie.1/device_reset &&
  echo "'iw dev' says:" >&2 &&
  iw dev &&
  echo "reloading drivers..." >&2 &&
  modprobe -a ath9k ath10k_pci
  echo "done. (exit code $?)" >&2
} 2>&1 | logos ath10k-reset