IRQ support using Linux kernel Character Device + Posix threads (#961)

* use pthread with Linux kernel's char-dev API
* [example] change IRQ_PIN number
* Add timeout to interrupt example
* read() kernel event buffer and track event sequence number
* code cleanup (in all Linux driver files)
* switch RPi driver to char-dev IRQ
* wrap wiringPiIsr() into attachInterrupt()
* adjust build systems to not rely on pigpio for IRQ support
* use IRQException instead of GPIOException
* make defined RF24_LINUX_GPIO_CHIP more agnostic of selected driver (applied to RPi and SPIDEV drivers)
* fix compiling wiringPi with examples using old makefile
* add C linkage instead of declaring extern functions
* reviewed wiringPi/spi wrapper
* move gpiochipX init out of cache c'tors
* add wiringPi pin number for CE_PIN to linux examples

---------

Co-authored-by: TMRh20 <tmrh20@gmail.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.github/workflows/build_linux.yml

@@ -68,6 +68,7 @@ jobs:
           - "--driver=SPIDEV"
           - "--driver=MRAA"
           - "--driver=pigpio"
+          # disable wiringPi due to needing cross-compiled deps (see comment below)
           # - "--soc=BCM2835 --driver=wiringPi"
 
     env:
@@ -83,18 +84,20 @@ jobs:
           arm-linux-gnueabihf-gcc -v
           arm-linux-gnueabihf-g++ -v
 
-      - name: provide WiringPi
-        if: ${{ matrix.config-options == '--soc=BCM2835 --driver=wiringPi' }}
-        env:
-          CC: /usr/bin/arm-linux-gnueabihf-gcc
-          CFLAGS: "-I /usr/local/include -L /usr/local/lib -marm -mtune=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard -lcrypt -lrt"
-        run: |
-          git clone https://github.com/WiringPi/WiringPi
-          cd WiringPi
-          ./build
+      # NOTE: To cross-compile wiringPi, there needs to be cross-compiled `crypt` and `rt` libs
+      # Skip cross-compiling wiringPi to avoid this headache.
+      # - name: provide WiringPi
+      #   if: ${{ matrix.config-options == '--soc=BCM2835 --driver=wiringPi' }}
+      #   env:
+      #     CC: /usr/bin/arm-linux-gnueabihf-gcc
+      #     CFLAGS: "-I /usr/local/include -L /usr/local/lib -marm -mtune=arm1176jzf-s -mfpu=vfp -mfloat-abi=hard -lcrypt -lrt"
+      #   run: |
+      #     git clone https://github.com/WiringPi/WiringPi
+      #     cd WiringPi
+      #     ./build
 
       - name: provide pigpio
-        if: ${{ matrix.config-options == '--driver=pigpio' || endsWith(matrix.config-options, '--driver=RPi') }}
+        if: ${{ matrix.config-options == '--driver=pigpio' }}
         run: |
           git clone https://github.com/joan2937/pigpio.git
           cd pigpio
@@ -118,7 +121,11 @@ jobs:
           cd mraa
           mkdir build
           cd build
-          cmake .. -D BUILDSWIGNODE=OFF -D BUILDARCH=arm
+          cmake .. \
+          -D BUILDSWIGNODE=OFF \
+          -D BUILDARCH=arm \
+          -D CMAKE_INSTALL_PREFIX=/usr/arm-linux-gnueabihf \
+          -D CMAKE_TOOLCHAIN_FILE=${{ github.workspace }}/cmake/toolchains/armhf.cmake
           sudo make install
           sudo bash -c 'echo "/usr/local/lib/arm-linux-gnueabihf" >> /etc/ld.so.conf'
           sudo ldconfig
@@ -133,10 +140,6 @@ jobs:
         run: sudo make install
 
       - name: make linux examples
-        # compiling examples for wiringPi is broken see issue #669
-        # executables linked to wiringPi additionally need to be linked to crypt and shm_open
-        # interruptConfigure.cpp example is incompatible with MRAA & wiringPi drivers
-        if: ${{ matrix.config-options != '--soc=BCM2835 --driver=wiringPi' && matrix.config-options != '--driver=MRAA' }}
         run: |
           cd examples_linux
           make

CMakeLists.txt

@@ -137,17 +137,12 @@ if(DEFINED RF24_SPI_SPEED)
     )
 endif()
 # allow user customization of default GPIO chip used with the SPIDEV driver
-if(DEFINED RF24_SPIDEV_GPIO_CHIP)
-    message(STATUS "RF24_SPIDEV_GPIO_CHIP set to ${RF24_SPIDEV_GPIO_CHIP}")
+if(DEFINED RF24_LINUX_GPIO_CHIP)
+    message(STATUS "RF24_LINUX_GPIO_CHIP set to ${RF24_LINUX_GPIO_CHIP}")
     target_compile_definitions(${LibTargetName} PUBLIC
-        RF24_SPIDEV_GPIO_CHIP="${RF24_SPIDEV_GPIO_CHIP}"
+        RF24_LINUX_GPIO_CHIP="${RF24_LINUX_GPIO_CHIP}"
     )
 endif()
-# conditionally disable interruot support (a pigpio specific feature)
-if("${LibPIGPIO}" STREQUAL "LibPIGPIO-NOTFOUND" OR DEFINED RF24_NO_INTERRUPT)
-    message(STATUS "Disabling IRQ pin support")
-    target_compile_definitions(${LibTargetName} PUBLIC RF24_NO_INTERRUPT)
-endif()
 
 
 #####################################

Makefile

@@ -21,15 +21,9 @@ OBJECTS=RF24.o
 ifeq ($(DRIVER), MRAA)
 OBJECTS+=spi.o gpio.o compatibility.o
 else ifeq ($(DRIVER), RPi)
-OBJECTS+=spi.o bcm2835.o compatibility.o
-ifneq (,$(findstring -lpigpio,$(SHARED_LINKER_LIBS)))
-OBJECTS+=interrupt.o
-endif
+OBJECTS+=spi.o bcm2835.o compatibility.o interrupt.o
 else ifeq ($(DRIVER), SPIDEV)
-OBJECTS+=spi.o gpio.o compatibility.o
-ifneq (,$(findstring -lpigpio,$(SHARED_LINKER_LIBS)))
-OBJECTS+=interrupt.o
-endif
+OBJECTS+=spi.o gpio.o compatibility.o interrupt.o
 else ifeq ($(DRIVER), wiringPi)
 OBJECTS+=spi.o
 else ifeq ($(DRIVER), pigpio)

configure

@@ -3,8 +3,6 @@
 CROSS_CC=arm-linux-gnueabihf-gcc
 CROSS_CXX=arm-linux-gnueabihf-g++
 
-pigpio_detected=0
-
 function help {
 cat <<EOF
 configure script for RF24 library.
@@ -58,11 +56,6 @@ function execute_check {
     fi
 }
 
-if [[ -f "/usr/lib/libpigpio.so" || -f "/usr/local/lib/libpigpio.so" || -f "/usr/arm-linux-gnueabihf/lib/libpigpio.so" ]]; then
-    echo "[INFO] pigpio lib found."
-    pigpio_detected=1
-fi
-
 function die {
     echo "[ERROR] $1"
     exit $2
@@ -192,7 +185,7 @@ function detect_driver {
         result=MRAA
     elif [[ $(execute_check "${REMOTE_LDCONFIG} -p | grep liblittlewire-spi") ]]; then
         result=LittleWire
-    elif [ $pigpio_detected -eq 1 ]; then
+    elif [[ -f "/usr/lib/libpigpio.so" || -f "/usr/local/lib/libpigpio.so" || -f "/usr/arm-linux-gnueabihf/lib/libpigpio.so" ]]; then
         result=pigpio
     else
         result=""
@@ -407,24 +400,12 @@ fi
 
 case ${DRIVER} in
 wiringPi)
-    SHARED_LINKER_LIBS+=" -lpigpio -lwiringPi"
+    SHARED_LINKER_LIBS+=" -lwiringPi"
     CFLAGS+=" -lwiringPi"
     ;;
 SPIDEV)
-    if [ $pigpio_detected -eq 1 ]; then
-        echo "[INFO] linking to pigpio for interrupt compatibility"
-        SHARED_LINKER_LIBS+=" -lpigpio"
-    else
-        CFLAGS+=" -DRF24_NO_INTERRUPT"
-    fi
     ;;
 RPi)
-    if [ $pigpio_detected -eq 1 ]; then
-        echo "[INFO] linking to pigpio for interrupt compatibility"
-        SHARED_LINKER_LIBS+=" -lpigpio"
-    else
-        CFLAGS+=" -DRF24_NO_INTERRUPT"
-    fi
     ;;
 MRAA)
     SHARED_LINKER_LIBS+=" -lmraa"
@@ -433,11 +414,7 @@ LittleWire)
     SHARED_LINKER_LIBS+=" -llittlewire-spi"
     ;;
 pigpio)
-    if [ $pigpio_detected -eq 0 ]; then
-        die "[ERROR] pigpio was not detected. Make sure pigpio is installed." 2
-    else
-        SHARED_LINKER_LIBS+=" -lpigpio"
-    fi
+    SHARED_LINKER_LIBS+=" -lpigpio"
     ;;
 *)
     die "Unsupported DRIVER: ${DRIVER}." 2

examples_linux/CMakeLists.txt

@@ -24,7 +24,7 @@ find_library(RF24 rf24 REQUIRED)
 message(STATUS "using RF24 library: ${RF24}")
 
 # conditionally append "interruptConfigure" to the EXAMPLES_LIST
-if("${RF24_DRIVER}" STREQUAL "MRAA" OR "${RF24_DRIVER}" STREQUAL "wiringPi" OR "${LibPIGPIO}" STREQUAL "LibPIGPIO-NOTFOUND")
+if("${RF24_DRIVER}" STREQUAL "MRAA")
     message(STATUS "Skipping interruptConfigure.cpp example as it is incompatible with selected driver library")
 else() # not using MRAA or wiringPi drivers (or pigpio lib was found)
     list(APPEND EXAMPLES_LIST interruptConfigure)
@@ -52,26 +52,15 @@ elseif("${RF24_DRIVER}" STREQUAL "wiringPi")
     else()
         message(FATAL "Lib ${RF24_DRIVER} not found.")
     endif()
-elseif(NOT "${LibPIGPIO}" STREQUAL "LibPIGPIO-NOTFOUND" AND NOT DEFINED RF24_NO_INTERUPT)
-    if(NOT "${RF24_DRIVER}" STREQUAL "pigpio")
-        message(STATUS "linking to ${LibPIGPIO} for interrupt support")
-    else()
-        message(STATUS "linking to ${LibPIGPIO}")
-    endif()
+elseif(NOT "${LibPIGPIO}" STREQUAL "LibPIGPIO-NOTFOUND")
+    message(STATUS "linking to ${LibPIGPIO}")
     # linking to pigpio requires pthread to be listed as last linked lib
     list(APPEND linked_libs ${LibPIGPIO} pthread)
-else()
-    message(STATUS "Disabling IRQ pin support")
 endif()
 
 foreach(example ${EXAMPLES_LIST})
     #make a target
     add_executable(${example} ${example}.cpp)
-
-    # avoid including interrupt.h when pigpio is not available
-    if("${LibPIGPIO}" STREQUAL "LibPIGPIO-NOTFOUND" OR DEFINED RF24_NO_INTERRUPT)
-        target_compile_definitions(${example} PUBLIC RF24_NO_INTERRUPT)
-    endif()
 
     target_link_libraries(${example} PUBLIC ${linked_libs})
 endforeach()

examples_linux/Makefile

@@ -19,7 +19,7 @@ include ../Makefile.inc
 
 # define all programs
 PROGRAMS = gettingstarted acknowledgementPayloads manualAcknowledgements streamingData multiceiverDemo scanner
-ifneq (,$(findstring -lpigpio,$(SHARED_LINKER_LIBS)))
+ifneq ($(DRIVER), MRAA)
 PROGRAMS+=interruptConfigure
 endif
 

examples_linux/Makefile.examples

@@ -17,6 +17,8 @@ SOURCES = $(PROGRAMS:=.cpp)
 LIBS=-l$(LIB)
 ifeq ($(DRIVER), LittleWire)
 	LIBS+= -llittlewire-spi
+else ifeq ($(DRIVER), wiringPi)
+	LIBS+= -lwiringPi -lcrypt -lrt
 endif
 
 all: $(PROGRAMS)

examples_linux/acknowledgementPayloads.cpp

@@ -27,6 +27,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

examples_linux/gettingstarted.cpp

@@ -26,6 +26,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

examples_linux/interruptConfigure.cpp

@@ -22,7 +22,7 @@
 using namespace std;
 
 // We will be using the nRF24L01's IRQ pin for this example
-#define IRQ_PIN 12 // this needs to be a digital input capable pin
+#define IRQ_PIN 24 // this needs to be a digital input capable pin
 
 // this example is a sequential program. so we need to wait for the event to be handled
 volatile bool got_interrupt = false; // used to signify that the event started
@@ -35,6 +35,8 @@ volatile bool got_interrupt = false; // used to signify that the event started
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif
@@ -167,14 +169,14 @@ void master()
     // Test the "data ready" event with the IRQ pin
     cout << "\nConfiguring IRQ pin to ignore the 'data sent' event\n";
     radio.maskIRQ(true, false, false); // args = "data_sent", "data_fail", "data_ready"
-    cout << "   Pinging RX node for 'data ready' event...";
+    cout << "   Pinging RX node for 'data ready' event..." << endl;
     ping_n_wait(); // transmit a payload and detect the IRQ pin
     pl_iterator++; // increment iterator for next test
 
     // Test the "data sent" event with the IRQ pin
     cout << "\nConfiguring IRQ pin to ignore the 'data ready' event\n";
     radio.maskIRQ(false, false, true); // args = "data_sent", "data_fail", "data_ready"
-    cout << "   Pinging RX node for 'data sent' event...";
+    cout << "   Pinging RX node for 'data sent' event..." << endl;
     radio.flush_tx(); // flush payloads from any failed prior test
     ping_n_wait();    // transmit a payload and detect the IRQ pin
     pl_iterator++;    // increment iterator for next test
@@ -196,7 +198,7 @@ void master()
     // test the "data fail" event with the IRQ pin
     cout << "\nConfiguring IRQ pin to reflect all events\n";
     radio.maskIRQ(0, 0, 0); // args = "data_sent", "data_fail", "data_ready"
-    cout << "   Pinging inactive RX node for 'data fail' event...";
+    cout << "   Pinging inactive RX node for 'data fail' event..." << endl;
     ping_n_wait(); // transmit a payload and detect the IRQ pin
 
     // CE pin is still HIGH which consumes more power. Example is now idling so...
@@ -250,7 +252,12 @@ void ping_n_wait()
     // use the non-blocking call to write a payload and begin transmission
     // the "false" argument means we are expecting an ACK packet response
     radio.startFastWrite(tx_payloads[pl_iterator], tx_pl_size, false);
+    uint32_t timer = millis();
     while (!got_interrupt) {
+        if (millis() - timer > 500) {
+            cout << "\tIRQ NOT received" << endl;
+            break;
+        }
         /*
          * IRQ pin is LOW when activated. Otherwise it is always HIGH
          * Wait in this empty loop until IRQ pin is activated.

examples_linux/manualAcknowledgements.cpp

@@ -32,6 +32,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

examples_linux/multiceiverDemo.cpp

@@ -30,6 +30,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

examples_linux/ncurses/CMakeLists.txt

@@ -18,6 +18,3 @@ target_link_libraries(${example} PUBLIC
     ${linked_libs}
     ${CURSES_LIBRARIES}
 )
-if("${LibPIGPIO}" STREQUAL "LibPIGPIO-NOTFOUND" OR DEFINED RF24_NO_INTERRUPT)
-    target_compile_definitions(${example} PUBLIC RF24_NO_INTERRUPT)
-endif()

examples_linux/ncurses/scanner_curses.cpp

@@ -33,6 +33,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

examples_linux/readme.md

@@ -1,3 +1,3 @@
 Note: These examples were originally designed for RPi, but should work on any supported Linux platform, with the proper pin configuration.
 
-See http://tmrh20.github.io/RF24 for more information
+See http://nRF24.github.io/RF24 for more information

examples_linux/scanner.cpp

@@ -58,6 +58,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

examples_linux/streamingData.cpp

@@ -28,6 +28,8 @@ using namespace std;
 #define CSN_PIN 0
 #ifdef MRAA
     #define CE_PIN 15 // GPIO22
+#elif defined(RF24_WIRINGPI)
+    #define CE_PIN 3 // GPIO22
 #else
     #define CE_PIN 22
 #endif

pyRF24/setup.py

@@ -35,7 +35,6 @@
                 os.environ[identifier] = value
 
 except FileNotFoundError:  # assuming lib was built & installed with CMake
-
     # get LIB_VERSION from library.properties file for Arduino IDE
     with open(os.path.join(git_dir, "library.properties"), "r", encoding="utf-8") as f:
         for line in f.read().splitlines():
@@ -44,7 +43,6 @@
 
 # check C++ RF24 lib is installed
 finally:
-
     # check for possible linker flags set via CFLAGS environment variable
     for flag in cflags.split("-"):
         if flag.startswith("L"):
@@ -71,13 +69,6 @@
             )
         )
 
-    # avoid IRQ support if pigpio is not available; link to pigpio if it is found
-    found_pigpio = False
-    for symlink_loc in symlink_directory:
-        if os.path.exists(symlink_loc + "/libpigpio.so"):
-            found_pigpio = True
-    # IRQ pin features will be implemented in python via pigpio's python API or RPi.GPIO
-    cflags += " -DRF24_NO_INTERRUPT"
 
 # append any additionally found compiler flags
 os.environ["CFLAGS"] = cflags
@@ -114,7 +105,7 @@
         Extension(
             "RF24",
             sources=["pyRF24.cpp"],
-            libraries=["rf24", BOOST_LIB] + (["pigpio"] if found_pigpio else [])
+            libraries=["rf24", BOOST_LIB],
         )
     ],
 )