gpio: add cdev v2 impl

CMakeLists.txt

@@ -7,13 +7,19 @@ if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE Release)
 endif()
 
-# Check for Linux kernel header files for character device GPIO support
-include(CheckIncludeFiles)
-CHECK_INCLUDE_FILES(linux/gpio.h HAVE_CDEV_GPIO_HEADERS)
-if(NOT HAVE_CDEV_GPIO_HEADERS)
-message(WARNING "Linux kernel header files not found for character device GPIO support. c-periphery will be built with legacy sysfs GPIO support only.")
+# Check Linux kernel header files for character device GPIO support
+include(CheckSymbolExists)
+check_symbol_exists(GPIO_V2_LINES_MAX linux/gpio.h HAVE_GPIO_CDEV_V2)
+check_symbol_exists(GPIO_GET_LINEEVENT_IOCTL linux/gpio.h HAVE_GPIO_CDEV_V1)
+if(HAVE_GPIO_CDEV_V2)
+    set(GPIO_CDEV_SUPPORT 2)
+elseif(HAVE_GPIO_CDEV_V1)
+    set(GPIO_CDEV_SUPPORT 1)
+else()
+    set(GPIO_CDEV_SUPPORT 0)
+    message(WARNING "Missing character device GPIO support in Linux kernel header files. c-periphery will be built with legacy sysfs GPIO support only.")
 endif()
-add_definitions(-DPERIPHERY_GPIO_CDEV_SUPPORT=$<BOOL:${HAVE_CDEV_GPIO_HEADERS}>)
+add_definitions(-DPERIPHERY_GPIO_CDEV_SUPPORT=${GPIO_CDEV_SUPPORT})
 
 # Library version
 set(VERSION "2.3.1")

Makefile

@@ -1,5 +1,5 @@
 LIB = periphery.a
-SRCS = src/gpio.c src/gpio_cdev_v1.c src/gpio_sysfs.c src/led.c src/pwm.c src/spi.c src/i2c.c src/mmio.c src/serial.c src/version.c
+SRCS = src/gpio.c src/gpio_cdev_v2.c src/gpio_cdev_v1.c src/gpio_sysfs.c src/led.c src/pwm.c src/spi.c src/i2c.c src/mmio.c src/serial.c src/version.c
 
 SRCDIR = src
 OBJDIR = obj
@@ -10,7 +10,10 @@ TEST_PROGRAMS = $(basename $(wildcard tests/*.c))
 
 OBJECTS = $(patsubst $(SRCDIR)/%.c,$(OBJDIR)/%.o,$(SRCS))
 
-GPIO_CDEV_SUPPORT := $(shell ! echo "\#include <linux/gpio.h>" | $(CC) -E - >/dev/null 2>&1; echo $$?)
+GPIO_CDEV_V1_SUPPORT := $(shell ! echo -e "#include <linux/gpio.h>\n#ifndef GPIO_GET_LINEEVENT_IOCTL\n#error\n#endif" | $(CC) -E - >/dev/null 2>&1; echo $$?)
+GPIO_CDEV_V2_SUPPORT := $(shell ! echo -e "#include <linux/gpio.h>\n#ifndef GPIO_V2_LINES_MAX\n#error\n#endif" | $(CC) -E - >/dev/null 2>&1; echo $$?)
+GPIO_CDEV_SUPPORT = $(if $(filter 1,$(GPIO_CDEV_V2_SUPPORT)),2,$(if $(filter 1,$(GPIO_CDEV_V1_SUPPORT)),1,0))
+
 COMMIT_ID := $(shell git describe --abbrev --always --tags --dirty 2>/dev/null || echo "")
 
 OPT ?= -O3

src/gpio.c

@@ -183,3 +183,36 @@ const char *gpio_errmsg(gpio_t *gpio) {
     return gpio->error.errmsg;
 }
 
+#if !PERIPHERY_GPIO_CDEV_SUPPORT
+
+int gpio_open(gpio_t *gpio, const char *path, unsigned int line, gpio_direction_t direction)  {
+    (void)path;
+    (void)line;
+    (void)direction;
+    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
+}
+
+int gpio_open_name(gpio_t *gpio, const char *path, const char *name, gpio_direction_t direction) {
+    (void)gpio;
+    (void)path;
+    (void)name;
+    (void)direction;
+    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
+}
+
+int gpio_open_advanced(gpio_t *gpio, const char *path, unsigned int line, const gpio_config_t *config) {
+    (void)path;
+    (void)line;
+    (void)config;
+    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
+}
+
+int gpio_open_name_advanced(gpio_t *gpio, const char *path, const char *name, const gpio_config_t *config) {
+    (void)path;
+    (void)name;
+    (void)config;
+    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
+}
+
+#endif
+

src/gpio_cdev_v1.c

@@ -17,21 +17,15 @@
 #include "gpio.h"
 #include "gpio_internal.h"
 
-#if PERIPHERY_GPIO_CDEV_SUPPORT
+#if PERIPHERY_GPIO_CDEV_SUPPORT == 1
 #include <linux/gpio.h>
-
-/* Disable cdev support when building with older kernel headers that don't yet
- * support line events in the gpio-cdev abi */
-#ifndef GPIO_GET_LINEEVENT_IOCTL
-#undef PERIPHERY_GPIO_CDEV_SUPPORT
-#endif
 #endif
 
 /*********************************************************************************/
-/* cdev implementation */
+/* cdev v1 implementation */
 /*********************************************************************************/
 
-#if PERIPHERY_GPIO_CDEV_SUPPORT
+#if PERIPHERY_GPIO_CDEV_SUPPORT == 1
 
 static int _gpio_cdev_reopen(gpio_t *gpio, gpio_direction_t direction, gpio_edge_t edge, gpio_bias_t bias, gpio_drive_t drive, bool inverted) {
     uint32_t flags = 0;
@@ -585,36 +579,5 @@ int gpio_open_name(gpio_t *gpio, const char *path, const char *name, gpio_direct
     return gpio_open_name_advanced(gpio, path, name, &config);
 }
 
-#else
-
-int gpio_open(gpio_t *gpio, const char *path, unsigned int line, gpio_direction_t direction)  {
-    (void)path;
-    (void)line;
-    (void)direction;
-    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
-}
-
-int gpio_open_name(gpio_t *gpio, const char *path, const char *name, gpio_direction_t direction) {
-    (void)gpio;
-    (void)path;
-    (void)name;
-    (void)direction;
-    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
-}
-
-int gpio_open_advanced(gpio_t *gpio, const char *path, unsigned int line, const gpio_config_t *config) {
-    (void)path;
-    (void)line;
-    (void)config;
-    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
-}
-
-int gpio_open_name_advanced(gpio_t *gpio, const char *path, const char *name, const gpio_config_t *config) {
-    (void)path;
-    (void)name;
-    (void)config;
-    return _gpio_error(gpio, GPIO_ERROR_UNSUPPORTED, 0, "c-periphery library built without character device GPIO support.");
-}
-
 #endif