cpu/native: add Linux GPIO implementation

cpu/native/Makefile.dep

@@ -0,0 +1,6 @@
+ifneq (,$(filter periph_gpio,$(USEMODULE)))
+# Hardware GPIO access is only available on Linux hosts
+ifeq ($(OS),Linux)
+  USEMODULE += periph_gpio_linux
+endif
+endif

cpu/native/Makefile.features

@@ -5,3 +5,8 @@ FEATURES_PROVIDED += periph_cpuid
 FEATURES_PROVIDED += periph_hwrng
 FEATURES_PROVIDED += periph_pm
 FEATURES_PROVIDED += periph_pwm
+
+# Hardware GPIO access is only available on Linux hosts
+ifeq ($(OS),Linux)
+  FEATURES_PROVIDED += periph_gpio periph_gpio_irq
+endif

cpu/native/include/gpiodev_linux.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2019 Benjamin Valentin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for
+ * more details.
+ */
+
+/**
+ * @defgroup    drivers_gpio_linux Linux User Mode GPIO Driver
+ * @ingroup     cpu_native
+ * @brief       Implementation of GPIO access from Linux User Space
+ *
+ * This module allows to connect a RIOT application that runs on a Linux host to
+ * the physical GPIO pins of that host. To do so, the application has to be
+ * compiled for the native board in a Linux environment.
+ *
+ * GPIO support is automatically included if either a module requiring the
+ * `PERIPH_GPIO` feature is added to the application or if it is explicitly
+ * listed as `FEATURES_REQUIRED` in the application's Makefile.
+ *
+ * At runtime, the process has to be connected to a specific GPIO bank on the host
+ * machine. GPIO banks are exposed as `/dev/gpiochipN` character files, where N
+ * is the bank ID to which several GPIO pins are connected.
+ *
+ * Example:
+ *
+ * ```
+ * $ ./riot_native_app --gpio=/dev/gpiochip0 --gpio=/dev/gpiochip1
+ * ```
+ *
+ * This will add `/dev/gpiochip0` and `/dev/gpiochip1` as PORT(0) and PORT(1) in RIOT.
+ * The first pin can be used with PIN(0,0) as `gpio_t`, the second one on the first
+ * port would be PIN(0,1) and so on.
+ *
+ * Please refer to your board's documentation for the mapping of the pins.
+ *
+ * @{
+ *
+ * @file
+ * @brief       Implementation of GPIO access from Linux User Space
+ *
+ * @author      Benjamin Valentin <benpicco@googlemail.com>
+ */
+
+#ifndef GPIODEV_LINUX_H
+#define GPIODEV_LINUX_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   register `/dev/gpiochip*` device to be used for GPIO
+ *
+ * @param[in] device   The gpiochip device to open.
+ *
+ * @return             0 on success, error otherwise
+ */
+int gpio_linux_setup(const char* device);
+
+/**
+ * @brief   shutdown GPIO subsystem
+ *
+ * This closes all GPIO fds.
+ */
+void gpio_linux_teardown(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GPIODEV_LINUX_H */
+/** @} */

cpu/native/include/periph_cpu.h

@@ -32,6 +32,60 @@ extern "C" {
 #define CPUID_LEN           (4U)
 #endif
 
+/* GPIO configuration only if the module is available (=Linux) */
+#if defined(MODULE_PERIPH_GPIO_LINUX) || defined(DOXYGEN)
+#include <linux/gpio.h>
+
+/**
+ * @name GPIO Configuration
+ */
+
+/**
+ * @brief   The offset between Port and Pin
+ */
+#define GPIO_PORT_SHIFT     (24)
+
+/**
+ * @brief   Define a custom GPIO_PIN macro for native
+ */
+#define GPIO_PIN(port, pin) (gpio_t)((port << GPIO_PORT_SHIFT) | pin)
+
+#define HAVE_GPIO_MODE_T
+#ifndef GPIOHANDLE_REQUEST_PULL_DOWN
+#define GPIOHANDLE_REQUEST_PULL_DOWN    (0xFF)
+#endif
+#ifndef GPIOHANDLE_REQUEST_PULL_UP
+#define GPIOHANDLE_REQUEST_PULL_UP      (0xFF)
+#endif
+
+/**
+ * @brief   Available pin modes
+ *
+ * Generally, a pin can be configured to be input or output. In output mode, a
+ * pin can further be put into push-pull or open drain configuration. Though
+ * this is supported by most platforms, this is not always the case, so driver
+ * implementations may return an error code if a mode is not supported.
+ */
+typedef enum {
+    GPIO_IN    = GPIOHANDLE_REQUEST_INPUT,
+    GPIO_IN_PD = GPIOHANDLE_REQUEST_INPUT | GPIOHANDLE_REQUEST_PULL_DOWN,
+    GPIO_IN_PU = GPIOHANDLE_REQUEST_INPUT | GPIOHANDLE_REQUEST_PULL_UP,
+    GPIO_OUT   = GPIOHANDLE_REQUEST_OUTPUT,
+    GPIO_OD    = GPIOHANDLE_REQUEST_OPEN_DRAIN,
+    GPIO_OD_PU = GPIOHANDLE_REQUEST_OPEN_DRAIN | GPIOHANDLE_REQUEST_PULL_UP
+} gpio_mode_t;
+
+#define HAVE_GPIO_FLANK_T
+typedef enum {
+    GPIO_FALLING = GPIOEVENT_EVENT_FALLING_EDGE,    /**< emit interrupt on falling flank */
+    GPIO_RISING = GPIOEVENT_EVENT_RISING_EDGE,      /**< emit interrupt on rising flank */
+    GPIO_BOTH = GPIO_FALLING | GPIO_RISING          /**< emit interrupt on both flanks */
+} gpio_flank_t;
+
+/** @} */
+
+#endif /* MODULE_PERIPH_GPIO_LINUX | DOXYGEN */
+
 /**
  * @brief   Prevent shared timer functions from being used
  */

cpu/native/periph/gpio.c

@@ -19,6 +19,8 @@
 
 #include "periph/gpio.h"
 
+#ifndef MODULE_GPIO_NATIVE
+
 int gpio_init(gpio_t pin, gpio_mode_t mode) {
   (void) pin;
   (void) mode;
@@ -51,4 +53,7 @@ void gpio_write(gpio_t pin, int value) {
   (void) pin;
   (void) value;
 }
+
+#endif /* !MODULE_GPIO_NATIVE */
+
 /** @} */