PM16D17: Use user-land driver

The current PM16D17 kernel sensor driver is not using the existing
kernel API, but self-invented device tree bindings, which is rejected
while upstreaming, see [1].

This patch replaces the kernel driver with a user-land driver.

1. https://lore.kernel.org/linux-iio/[email protected]/

Signed-off-by: Baocheng Su <[email protected]>

recipes-app/iot2050-event-record/files/iot2050-event-record.py

@@ -15,6 +15,7 @@
 from datetime import datetime
 from systemd import journal
 from enum import Enum
+from pystemd.dbuslib import DBus, DbusMessage
 import grpc
 from gRPC.EventInterface.iot2050_event_pb2 import (
     WriteRequest,
@@ -127,33 +128,51 @@ def record_eio_events():
         time.sleep(5)
 
 
+class ProximitySensorDBus():
+    def __init__(self, critical_value: int):
+        self.critical_value = critical_value
+
+    def is_uncovered(self) -> bool:
+        with DBus() as bus:
+            res: DbusMessage = bus.call_method(
+                b"com.siemens.iot2050.pxmt",
+                b"/com/siemens/iot2050/pxmt",
+                b"com.siemens.iot2050.pxmt",
+                b"Retrieve",
+                [])
+            lux = int(res.body)
+            return lux < self.critical_value
+
+        return False
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
+
 
 IIO_IMU_PATH = "/sys/devices/platform/bus@100000/2030000.i2c/i2c-5/5-006a/"
-IIO_PRO_PATH = "/sys/devices/platform/bus@100000/2030000.i2c/i2c-5/5-0044/"
 def record_sensor_events():
     accel_x_raw = "{}/in_accel_x_raw"
     accel_y_raw = "{}/in_accel_y_raw"
     accel_z_raw = "{}/in_accel_z_raw"
-    pro_raw = "{}/in_proximity0_raw"
     imu_w = os.walk(IIO_IMU_PATH)
-    pro_w = os.walk(IIO_PRO_PATH)
     for (dirpath, dirnames, filenames) in imu_w:
         if "in_accel_x_raw" in filenames:
             accel_x_raw = accel_x_raw.format(dirpath)
             accel_y_raw = accel_y_raw.format(dirpath)
             accel_z_raw = accel_z_raw.format(dirpath)
             break
-    for (dirpath, dirnames, filenames) in pro_w:
-        if "in_proximity0_raw" in filenames:
-            pro_raw = pro_raw.format(dirpath)
-            break
+
+    lux_critical_value = int(os.getenv('LUX_CRITICAL_VALUE', '100'))
+    pxmt_sensor = ProximitySensorDBus(critical_value=lux_critical_value)
     with open(accel_x_raw, 'r') as x, \
         open(accel_y_raw, 'r') as y, \
         open(accel_z_raw, 'r') as z, \
-        open(pro_raw, 'r') as l:
+        pxmt_sensor as l:
         is_uncovered = False
         accel_critical_value = int(os.getenv('ACCEL_CRITICAL_VALUE'))
-        lux_critical_value = int(os.getenv('LUX_CRITICAL_VALUE'))
         while True:
             # Detect tilt sensor event
             x.seek(0)
@@ -176,15 +195,15 @@ def record_sensor_events():
                 write_event(EVENT_TYPES["tilt"], tilted_event)
 
             # Detect tamper sensor event
-            l.seek(0)
-            lux = int(l.read())
-            if lux < lux_critical_value and not is_uncovered:
-                is_uncovered = True
-                now = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
-                uncover_event = EVENT_STRINGS["uncover"].format(now)
-                write_event(EVENT_TYPES["uncover"], uncover_event)
-            elif lux > lux_critical_value and is_uncovered:
-                is_uncovered = False
+            if is_uncovered:
+                is_uncovered = l.is_uncovered()
+            else:
+                is_uncovered = l.is_uncovered()
+                if is_uncovered:
+                    now = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+                    uncover_event = EVENT_STRINGS["uncover"].format(now)
+                    write_event(EVENT_TYPES["uncover"], uncover_event)
+
 
 def event_record():
     if not is_grpc_servers_ready():

recipes-app/iot2050-event-record/iot2050-event-record_0.1.bb

@@ -32,7 +32,7 @@ SRC_URI = " \
 
 S = "${WORKDIR}/src"
 
-DEBIAN_DEPENDS = "python3, python3-grpcio, python3-psutil, python3-systemd"
+DEBIAN_DEPENDS = "python3, python3-grpcio, python3-psutil, python3-systemd, python3-pystemd"
 
 do_install() {
     install -v -d ${D}/usr/lib/iot2050/event/

recipes-core/images/iot2050-image-example.bb

@@ -43,6 +43,7 @@ IMAGE_INSTALL += " \
     tee-supplicant \
     iot2050-event-record \
     linux-headers-${KERNEL_NAME} \
+    iot2050-proximity-driver \
     "
 
 IOT2050_NODE_RED_SUPPORT ?= "1"

recipes-core/iot2050-proximity-driver/files/src/Makefile

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: Copyright (c) Siemens AG, 2025
+# SPDX-FileContributor: Authored by Su Bao Cheng <[email protected]>
+
+CROSS_COMPILE ?= aarch64-linux-gnu-
+
+CC = $(CROSS_COMPILE)gcc
+
+LDFLAGS = -lsystemd
+
+TARGET = iot2050-pxmtd
+
+INSTALL ?= install
+
+DESTDIR ?= /
+
+SRC = main.c \
+	dbus-service.c \
+	sensor.c
+
+.PHONY: all clean install
+
+all: $(TARGET)
+
+$(TARGET): $(SRC)
+	$(CC) $(CFLAGS) -o $(TARGET) $(SRC) $(LDFLAGS)
+
+clean:
+	rm -f $(TARGET)
+
+install:
+	$(INSTALL) -v -d $(DESTDIR)/usr/bin
+	$(INSTALL) -v -d $(DESTDIR)/etc/dbus-1/system.d
+	$(INSTALL) -v -m 0755 $(TARGET) $(DESTDIR)/usr/bin
+	$(INSTALL) -v -m 0644 com.siemens.iot2050.pxmt.conf \
+		$(DESTDIR)/etc/dbus-1/system.d
+	$(INSTALL) -v -d ${DESTDIR}/lib/systemd/system/
+	$(INSTALL) -v -m 0644 iot2050-proximity-driver.service\
+		${DESTDIR}/lib/systemd/system/

recipes-core/iot2050-proximity-driver/files/src/com.siemens.iot2050.pxmt.conf

@@ -0,0 +1,9 @@
+<!DOCTYPE busconfig PUBLIC
+ "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
+ "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+  <policy user="root">
+    <allow own="com.siemens.iot2050.pxmt"/>
+    <allow send_interface="com.siemens.iot2050.pxmt"/>
+  </policy>
+</busconfig>

recipes-core/iot2050-proximity-driver/files/src/dbus-service.c

@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: MIT
+ * SPDX-FileCopyrightText: Copyright (c) Siemens AG, 2025
+ * SPDX-FileContributor: Authored by Su Bao Cheng <[email protected]>
+ */
+
+#include <systemd/sd-bus.h>
+#include <errno.h>
+#include <sys/capability.h>
+#include "dbus-service.h"
+
+typedef int (*retrieve_callback_t)(uint16_t *);
+
+static retrieve_callback_t iot2050_pxmtd_retrieve_cb = NULL;
+
+static int iot2050_pxmtd_retrieve(sd_bus_message *m,
+				  void *userdata,
+				  sd_bus_error *ret_error)
+{
+	if (!iot2050_pxmtd_retrieve_cb)
+		return -ENXIO;
+
+	uint16_t ps_val;
+	int ret = iot2050_pxmtd_retrieve_cb(&ps_val);
+	if (ret < 0)
+		return ret;
+
+	return sd_bus_reply_method_return(m, "q", ps_val);
+}
+
+static const sd_bus_vtable iot2050_pxmtd_vtable[] = {
+	SD_BUS_VTABLE_START(0),
+	SD_BUS_METHOD("Retrieve",
+		      SD_BUS_NO_ARGS,
+		      "q",
+		      iot2050_pxmtd_retrieve,
+		      SD_BUS_VTABLE_UNPRIVILEGED),
+	SD_BUS_VTABLE_END
+};
+
+int dbus_serve(retrieve_callback_t cb)
+{
+	sd_bus_slot *slot = NULL;
+	sd_bus *bus = NULL;
+	int ret;
+
+	ret = sd_bus_open_system(&bus);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to connect to system bus: %s\n",
+			strerror(-ret));
+		goto out;
+	}
+
+	iot2050_pxmtd_retrieve_cb = cb;
+
+	ret = sd_bus_add_object_vtable(bus, &slot,
+				       "/com/siemens/iot2050/pxmt",
+				       "com.siemens.iot2050.pxmt",
+				       iot2050_pxmtd_vtable, NULL);
+	if (ret < 0) {
+		fprintf(stderr, "Failed to set dbus service property: %s\n",
+			strerror(-ret));
+		goto out;
+	}
+
+        ret = sd_bus_request_name(bus, "com.siemens.iot2050.pxmt", 0);
+        if (ret < 0) {
+                fprintf(stderr, "Failed to acquire service name: %s\n",
+			strerror(-ret));
+                goto out;
+        }
+
+        for (;;) {
+                ret = sd_bus_process(bus, NULL);
+                if (ret < 0) {
+                        fprintf(stderr, "Failed to process bus: %s\n",
+				strerror(-ret));
+                        goto out;
+                }
+                if (ret > 0)
+                        continue;
+
+                ret = sd_bus_wait(bus, (uint64_t) -1);
+                if (ret < 0) {
+                        fprintf(stderr, "Failed to wait on bus: %s\n",
+				strerror(-ret));
+                        goto out;
+                }
+        }
+
+	ret = 0;
+out:
+	sd_bus_slot_unref(slot);
+	sd_bus_unref(bus);
+
+	return ret;
+}

recipes-core/iot2050-proximity-driver/files/src/dbus-service.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: MIT
+ * SPDX-FileCopyrightText: Copyright (c) Siemens AG, 2025
+ * SPDX-FileContributor: Authored by Su Bao Cheng <[email protected]>
+ */
+
+#ifndef IOT2050_PXMTD_DBUS_SERVICE_H
+#define IOT2050_PXMTD_DBUS_SERVICE_H
+
+#include <stdint.h>
+
+typedef int (*retrieve_callback_t)(uint16_t *);
+
+int dbus_serve(retrieve_callback_t cb);
+
+#endif /* IOT2050_PXMTD_DBUS_SERVICE_H */

recipes-core/iot2050-proximity-driver/files/src/iot2050-proximity-driver.service

@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: Copyright (c) Siemens AG, 2025
+# SPDX-FileContributor: Authored by Su Bao Cheng <[email protected]>
+
+[Unit]
+Description=Userspace driver for the proximity sensor of IOT2050
+# Only run on IOT2050-SM variant
+ConditionFirmware=device-tree-compatible(siemens,iot2050-advanced-sm)
+ConditionVirtualization=!container
+
+[Service]
+Type=dbus
+BusName=com.siemens.iot2050.pxmt
+ExecStart=/usr/bin/iot2050-pxmtd
+Restart=always
+RestartSec=5
+ProtectSystem=strict
+ProtectHome=true
+NoNewPrivileges=true
+User=root
+
+[Install]
+WantedBy=multi-user.target
+Alias=dbus-com.siemens.iot2050.pxmt.service

recipes-core/iot2050-proximity-driver/files/src/main.c

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: MIT
+ * SPDX-FileCopyrightText: Copyright (c) Siemens AG, 2025
+ * SPDX-FileContributor: Authored by Su Bao Cheng <[email protected]>
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "sensor.h"
+#include "dbus-service.h"
+
+int main()
+{
+	setbuf(stdout, NULL);
+
+	int ret = init_sensor();
+	if (ret < 0) {
+		fprintf(stderr, "Failed to initialize the sensor: %s\n",
+			strerror(-ret));
+		exit(EXIT_FAILURE);
+	}
+
+	return dbus_serve(retrieve_sensor_data) == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}