i2c-imc-skylake: split the submission into a PCI patch and the driver
The driver reached the PCU function's config space by walking the ACPI MCFG
table and mapping the ECAM page itself. That is one leaf driver deciding
config-space policy, and no other driver in mainline does it, so it was the
single most likely reason for a NAK.
Move that decision where it belongs: the upstream series is now two patches,
a PCI/x86 accessor that forces the memory-mapped path with the core's
locking, and this driver on top of it. Reviewers on each side now get
something they can act on, and get_maintainer.pl selects the PCI and x86
people by itself.
Correctness work in the same pass:
- the completion bits are latched, so a command the engine never accepted
was indistinguishable from a completed one and returned the previous
transaction's data as valid. Require a positive sign that the engine
acted on the command;
- compare the command registers after every transfer against what the
driver left in them and fail with -EAGAIN on a mismatch. The original
iMC driver had this check and it is what makes an unarbitrated system
detectable instead of silently wrong;
- use the i2c core's suspended-adapter mechanism rather than a private
flag and -EHOSTDOWN;
- use devm_mutex_init(), drop the unnecessary pci_enable_device(), and
return -ENODEV rather than -EPERM from the default-off gate, which was
printing a driver-core error on every boot;
- mask GO when restoring a saved command word.
Stop attributing the dropped CF8/CFC write to System Management Mode. The
only evidence was a boot log line naming the access method, which says
nothing about who filters the write. tools/probe-cf8-write.sh is there to
settle it with an MSR_SMI_COUNT measurement.
Add Documentation/i2c/busses/i2c-imc-skylake.rst, which every other PC SMBus
driver has and which was explicitly asked for on the 2020 iMC thread, the
tools/ scripts for the hardware measurements the submission still owes, and
compat/pci-mmcfg-compat.h so the driver still builds out-of-tree against a
kernel without the new accessor while the source stays byte-identical to the
submitted patch.
This commit is contained in:
Simone
+234
-73
@@ -1,91 +1,252 @@
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#!/usr/bin/env bash
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# Smoke test for i2c-imc-skylake (pci_driver, no bus/dev/fn params).
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# Run after: make install OR make reload
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# Requires: root, i2c-tools (i2cdetect), module already loaded.
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# Read-only smoke test for i2c-imc-skylake.
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set -euo pipefail
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PASS=0
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FAIL=0
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CH0=""
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CH1=""
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CH0_ADDR=""
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CH1_ADDR=""
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_ok() { echo "PASS: $*"; ((PASS++)) || true; }
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_fail() { echo "FAIL: $*"; ((FAIL++)) || true; }
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echo "=== adapter list ==="
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i2cdetect -l | grep -i imc || _fail "no imc adapters visible"
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_bus() {
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i2cdetect -l 2>/dev/null | grep -i "imc.*channel $1" | awk '{print $1}' | tr -d 'i2c-'
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}
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CH0=$(_bus 0)
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CH1=$(_bus 1)
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if [ -n "$CH0" ]; then
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_ok "ch0 adapter at i2c-$CH0"
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if ((EUID == 0)); then
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SUDO=()
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else
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_fail "ch0 adapter not found"
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fi
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if [ -n "$CH1" ]; then
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_ok "ch1 adapter at i2c-$CH1"
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else
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_fail "ch1 adapter not found"
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fi
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# The engine has no QUICK/BYTE primitive, so `i2cdetect` cannot scan the bus
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# ("Bus doesn't support detection commands"). Probe SPD addresses directly with
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# a byte-data read of register 0x00 instead.
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_scan_spd() {
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local bus=$1 found=""
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echo "--- SPD scan bus $bus (byte-data read of reg 0x00) ---"
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for a in 0x50 0x51 0x52 0x53 0x54 0x55 0x56 0x57; do
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if v=$(i2cget -y "$bus" "$a" 0x00 2>/dev/null); then
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echo " $a present (reg0=$v)"
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found="$a"
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fi
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done
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[ -n "$found" ]
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}
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if [ -n "$CH0" ]; then
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echo ""
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if _scan_spd "$CH0"; then
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_ok "SPD device present on ch0"
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else
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_fail "no SPD device on ch0"
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SUDO=(sudo -n)
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if ! "${SUDO[@]}" true 2>/dev/null; then
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echo "Run as root or configure non-interactive sudo." >&2
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exit 2
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fi
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fi
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if [ -n "$CH1" ]; then
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echo ""
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_scan_spd "$CH1" && _ok "SPD device present on ch1" || true
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MODULE_PATH=${MODULE_PATH:-$(modinfo -n i2c-imc-skylake)}
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if [[ ! -r "$MODULE_PATH" ]]; then
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echo "Module not found: $MODULE_PATH" >&2
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exit 2
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fi
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echo ""
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echo "=== udev autoload ==="
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sudo rmmod i2c-imc-skylake
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sleep 1
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sudo udevadm trigger --subsystem-match=pci --action=add
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sleep 2
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if lsmod | grep i2c_imc_skylake >/dev/null; then
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_ok "udev autoload"
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else
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_fail "udev did not reload module — check /etc/modules-load.d/ or udev rules"
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_ok()
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{
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echo "PASS: $*"
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((PASS++)) || true
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}
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_fail()
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{
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echo "FAIL: $*"
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((FAIL++)) || true
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}
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_module_loaded()
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{
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lsmod | awk '$1 == "i2c_imc_skylake" { found = 1 } END { exit !found }'
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}
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_bus()
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{
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local channel=$1
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i2cdetect -l 2>/dev/null | awk -v channel="$channel" '
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tolower($0) ~ /imc.*channel/ && $0 ~ "channel " channel {
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sub(/^i2c-/, "", $1)
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print $1
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exit
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}'
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}
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_find_pci_device()
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{
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local device path vendor
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for path in /sys/bus/pci/devices/*; do
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[[ -r "$path/vendor" && -r "$path/device" ]] || continue
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read -r vendor < "$path/vendor"
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read -r device < "$path/device"
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if [[ "$vendor" == "0x8086" && "$device" == "0x2085" ]]; then
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printf '%s\n' "$path"
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return 0
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fi
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done
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return 1
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}
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_refresh_buses()
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{
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CH0=$(_bus 0)
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CH1=$(_bus 1)
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}
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_scan_spd()
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{
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local bus=$1 result_var=$2
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local address address_hex device readable="" value
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local found=false
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echo "--- SPD scan bus $bus (read-only BYTE_DATA) ---"
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for address in {80..87}; do
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printf -v address_hex '0x%02x' "$address"
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printf -v device '%d-%04x' "$bus" "$address"
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if [[ -L "/sys/bus/i2c/devices/$device/driver" ]]; then
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echo " $address_hex present (bound to $(basename "$(readlink "/sys/bus/i2c/devices/$device/driver")"))"
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found=true
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continue
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fi
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if value=$("${SUDO[@]}" i2cget -y "$bus" "$address_hex" 0x00 2>/dev/null); then
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echo " $address_hex present (reg0=$value)"
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found=true
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readable=${readable:-$address_hex}
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fi
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done
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printf -v "$result_var" '%s' "$readable"
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$found
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}
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_word_test()
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{
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local bus=$1 address=$2
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local byte0 byte1 expected word
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if ! byte0=$("${SUDO[@]}" i2cget -y "$bus" "$address" 0x00 2>/dev/null) ||
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! byte1=$("${SUDO[@]}" i2cget -y "$bus" "$address" 0x01 2>/dev/null) ||
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! word=$("${SUDO[@]}" i2cget -y "$bus" "$address" 0x00 w 2>/dev/null); then
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return 1
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fi
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expected=$((byte0 | (byte1 << 8)))
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((word == expected))
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}
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_nack_test()
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{
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local bus=$1
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local trace
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command -v strace >/dev/null || return 1
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trace=$("${SUDO[@]}" strace -qq -f -e trace=ioctl \
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i2cget -y "$bus" 0x77 0x00 2>&1 || true)
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grep -q '= -1 ENXIO' <<< "$trace"
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}
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_stress_reader()
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{
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local bus=$1 address=$2
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local iteration
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for iteration in {1..100}; do
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"${SUDO[@]}" i2cget -y "$bus" "$address" 0x02 >/dev/null 2>&1 || return 1
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done
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}
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_load_unsafe()
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{
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"${SUDO[@]}" insmod "$MODULE_PATH" allow_unsafe_access=1
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}
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DMESG_START=$("${SUDO[@]}" dmesg | wc -l)
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"${SUDO[@]}" modprobe i2c-dev
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_module_loaded && "${SUDO[@]}" rmmod i2c-imc-skylake
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_load_unsafe
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echo "=== adapter discovery ==="
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_refresh_buses
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[[ -n "$CH0" ]] && _ok "ch0 adapter at i2c-$CH0" || _fail "ch0 adapter not found"
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[[ -n "$CH1" ]] && _ok "ch1 adapter at i2c-$CH1" || _fail "ch1 adapter not found"
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if [[ -n "$CH0" ]]; then
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_scan_spd "$CH0" CH0_ADDR && _ok "SPD device present on ch0" || _fail "no SPD device on ch0"
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fi
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if [[ -n "$CH1" ]]; then
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_scan_spd "$CH1" CH1_ADDR && _ok "SPD device present on ch1" || _fail "no SPD device on ch1"
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fi
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echo ""
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echo "=== load/unload x5 (leak/oops) ==="
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for i in $(seq 1 5); do
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sudo rmmod i2c-imc-skylake
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sudo modprobe i2c-imc-skylake
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echo " cycle $i OK"
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echo "=== transfer semantics ==="
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if [[ -n "$CH0_ADDR" ]]; then
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_word_test "$CH0" "$CH0_ADDR" && _ok "WORD_DATA byte order on ch0" || _fail "WORD_DATA test on ch0"
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fi
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if [[ -n "$CH1_ADDR" ]]; then
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_word_test "$CH1" "$CH1_ADDR" && _ok "WORD_DATA byte order on ch1" || _fail "WORD_DATA test on ch1"
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fi
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if [[ -n "$CH0" ]]; then
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_nack_test "$CH0" && _ok "absent-device ENXIO on ch0" || _fail "expected ENXIO at address 0x77 on ch0"
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fi
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if [[ -n "$CH1" ]]; then
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_nack_test "$CH1" && _ok "absent-device ENXIO on ch1" || _fail "expected ENXIO at address 0x77 on ch1"
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fi
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if [[ -n "$CH0_ADDR" && -n "$CH1_ADDR" ]]; then
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_stress_reader "$CH0" "$CH0_ADDR" &
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pid0=$!
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_stress_reader "$CH1" "$CH1_ADDR" &
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pid1=$!
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stress_ok=true
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wait "$pid0" || stress_ok=false
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wait "$pid1" || stress_ok=false
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$stress_ok && _ok "concurrent 100-read stress on both channels" || _fail "concurrent read stress"
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fi
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echo "=== safe default and targeted udev event ==="
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PCI_DEVICE=$(_find_pci_device) || {
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_fail "PCI device 8086:2085 not found"
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PCI_DEVICE=""
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}
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if [[ -n "$PCI_DEVICE" ]]; then
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"${SUDO[@]}" rmmod i2c-imc-skylake
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"${SUDO[@]}" insmod "$MODULE_PATH"
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_refresh_buses
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if [[ -z "$CH0" && -z "$CH1" ]]; then
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_ok "default-off gate rejected bind without opt-in"
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else
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_fail "driver bound without allow_unsafe_access=1"
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fi
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_module_loaded && "${SUDO[@]}" rmmod i2c-imc-skylake
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if "${SUDO[@]}" udevadm trigger --action=add "$PCI_DEVICE" &&
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"${SUDO[@]}" udevadm settle --timeout=5; then
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_ok "targeted PCI udev event completed"
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else
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_fail "targeted PCI udev event failed"
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fi
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_module_loaded && "${SUDO[@]}" rmmod i2c-imc-skylake
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_load_unsafe
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fi
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echo "=== load/unload x20 ==="
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for iteration in {1..20}; do
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"${SUDO[@]}" rmmod i2c-imc-skylake
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_load_unsafe
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echo " cycle $iteration OK"
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done
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_ok "5 load/unload cycles completed"
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_ok "20 load/unload cycles completed"
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echo ""
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echo "=== dmesg tail ==="
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dmesg | tail -20
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echo "=== kernel messages produced by this test ==="
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NEW_DMESG=$("${SUDO[@]}" dmesg | tail -n "+$((DMESG_START + 1))")
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RELEVANT_DMESG=$(grep -Ei 'i2c-imc-skylake [0-9a-f]{4}:|BUG:|WARNING:|Oops:|KASAN:|lockdep' <<< "$NEW_DMESG" || true)
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printf '%s\n' "$RELEVANT_DMESG"
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if grep -Eiq 'BUG:|WARNING:|Oops:|KASAN:|lockdep' <<< "$NEW_DMESG"; then
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_fail "kernel warning/oops detected"
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else
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_ok "no kernel warning/oops detected"
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fi
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# The driver compares the command registers before and after every transfer.
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# A hit here means firmware, a BMC or CLTT is driving the same engine, which
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# invalidates every other result in this run.
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if grep -q 'another master is using the engine' <<< "$NEW_DMESG"; then
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_fail "foreign master detected on the engine; do not use this system"
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else
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_ok "no foreign master detected during the test"
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fi
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# Likewise for a command the engine never accepted: that path exists because
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# the done bits are latched and must not be mistaken for a fresh completion.
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if grep -q 'command not accepted' <<< "$NEW_DMESG"; then
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_fail "engine did not accept a command; config access path is unreliable"
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else
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_ok "every command was accepted by the engine"
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fi
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echo ""
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echo "=== result: $PASS passed, $FAIL failed ==="
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[ "$FAIL" -eq 0 ]
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((FAIL == 0))
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Reference in New Issue
Block a user