boards/raspberrypi-pico: Add buttons support example

This patch add support to use buttons example on raspberrypi-pico.
Note: unfortunately the raspberry-pico board doesn't have usables
buttons, then you need to add external buttons connected to GPIO16
and GPIO17.

Signed-off-by: Alan C. Assis <acassis@gmail.com>

boards/Kconfig

@@ -1853,6 +1853,8 @@ config ARCH_BOARD_RASPBERRYPI_PICO
 	bool "Raspberry Pi Pico board (not W)"
 	depends on ARCH_CHIP_RP2040
 	select ARCH_HAVE_LEDS
+	select ARCH_HAVE_BUTTONS
+	select ARCH_HAVE_IRQBUTTONS
 	---help---
 		This is a port to the Raspberry Pi Pico board.
 

boards/arm/rp2040/raspberrypi-pico/include/board.h

@@ -109,6 +109,15 @@
  * 2Hz, then a fatal error has been detected and the system has halted.
  */
 
+/* BUTTON definitions *******************************************************/
+
+#define NUM_BUTTONS       2
+
+#define BUTTON_USER1      0
+#define BUTTON_USER2      1
+#define BUTTON_USER1_BIT  (1 << BUTTON_USER1)
+#define BUTTON_USER2_BIT  (1 << BUTTON_USER2)
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/

boards/arm/rp2040/raspberrypi-pico/src/Make.defs

@@ -34,6 +34,10 @@ else
 CSRCS += rp2040_userleds.c
 endif
 
+ifeq ($(CONFIG_ARCH_BUTTONS),y)
+  CSRCS += rp2040_buttons.c
+endif
+
 DEPPATH += --dep-path board
 VPATH += :board
 CFLAGS += ${INCDIR_PREFIX}$(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)board$(DELIM)board

boards/arm/rp2040/raspberrypi-pico/src/rp2040_bringup.c

@@ -74,5 +74,15 @@ int rp2040_bringup(void)
     }
 #endif
 
+#ifdef CONFIG_INPUT_BUTTONS
+  /* Register the BUTTON driver */
+
+  ret = btn_lower_initialize("/dev/buttons");
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "ERROR: btn_lower_initialize() failed: %d\n", ret);
+    }
+#endif
+
   return OK;
 }

boards/arm/rp2040/raspberrypi-pico/src/rp2040_buttons.c

@@ -0,0 +1,177 @@
+/****************************************************************************
+ * boards/arm/rp2040/raspberrypi-pico/src/rp2040_buttons.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <errno.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/board.h>
+#include <arch/board/board.h>
+
+#include "rp2040_gpio.h"
+#include "rp2040_pico.h"
+
+#if defined(CONFIG_ARCH_BUTTONS)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#if defined(CONFIG_INPUT_BUTTONS) && !defined(CONFIG_ARCH_IRQBUTTONS)
+#  error "The NuttX Buttons Driver depends on IRQ support to work!\n"
+#endif
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/* Pin configuration for external raspberrypi-pico buttons. */
+
+static const uint32_t g_buttons[NUM_BUTTONS] =
+{
+  GPIO_BTN_USER1, GPIO_BTN_USER2
+};
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: board_button_initialize
+ *
+ * Description:
+ *   board_button_initialize() must be called to initialize button resources.
+ *   After that, board_buttons() may be called to collect the current state
+ *   of all buttons or board_button_irq() may be called to register button
+ *   interrupt handlers.
+ *
+ ****************************************************************************/
+
+uint32_t board_button_initialize(void)
+{
+  int i;
+
+  /* Configure the GPIO pins as inputs. And we will use interrupts */
+
+  for (i = 0; i < NUM_BUTTONS; i++)
+    {
+      /* Initialize input pin */
+
+      rp2040_gpio_init(g_buttons[i]);
+
+      /* pull-up = false : pull-down = false */
+
+      rp2040_gpio_set_pulls(g_buttons[i], false, false);
+    }
+
+  return NUM_BUTTONS;
+}
+
+/****************************************************************************
+ * Name: board_buttons
+ ****************************************************************************/
+
+uint32_t board_buttons(void)
+{
+  uint32_t ret = 0;
+  int i;
+
+  /* Check that state of each key */
+
+  for (i = 0; i < NUM_BUTTONS; i++)
+    {
+      /* A LOW value means that the key is pressed. */
+
+      bool released = rp2040_gpio_get(g_buttons[i]);
+
+      /* Accumulate the set of depressed (not released) keys */
+
+      if (!released)
+        {
+           ret |= (1 << i);
+        }
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Button support.
+ *
+ * Description:
+ *   board_button_initialize() must be called to initialize button resources.
+ *   After that, board_buttons() may be called to collect the current state
+ *   of all buttons or board_button_irq() may be called to register button
+ *   interrupt handlers.
+ *
+ *   After board_button_initialize() has been called, board_buttons() may be
+ *   called to collect the state of all buttons.  board_buttons() returns
+ *   an 32-bit bit set with each bit associated with a button.  See the
+ *   BUTTON_*_BIT definitions in board.h for the meaning of each bit.
+ *
+ *   board_button_irq() may be called to register an interrupt handler that
+ *   will be called when a button is depressed or released.  The ID value is
+ *   a button enumeration value that uniquely identifies a button resource.
+ *   See the BUTTON_* definitions in board.h for the meaning of enumeration
+ *   value.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_IRQBUTTONS
+int board_button_irq(int id, xcpt_t irqhandler, void *arg)
+{
+  int ret = -EINVAL;
+
+  /* The following should be atomic */
+
+  if (id >= MIN_IRQBUTTON && id <= MAX_IRQBUTTON)
+    {
+      /* Make sure the interrupt is disabled */
+
+      rp2040_gpio_disable_irq(g_buttons[id]);
+
+      /* Attach the interrupt handler */
+
+      ret = rp2040_gpio_irq_attach(g_buttons[id],
+                                   RP2040_GPIO_INTR_EDGE_LOW,
+                                   irqhandler,
+                                   arg);
+      if (ret < 0)
+        {
+          syslog(LOG_ERR, "ERROR: irq_attach() failed: %d\n", ret);
+          return ret;
+        }
+
+      /* Enable interruption for this pin */
+
+      rp2040_gpio_enable_irq(g_buttons[id]);
+    }
+
+  return ret;
+}
+#endif
+
+#endif /* CONFIG_ARCH_BUTTONS */

boards/arm/rp2040/raspberrypi-pico/src/rp2040_pico.h

@@ -31,6 +31,19 @@
 
 #define GPIO_LED1       25 /* The board's LED is connected to this pin */
 
+/* Buttons */
+
+/* Buttons GPIO pins definition */
+
+#define GPIO_BTN_USER1     16
+#define GPIO_BTN_USER2     17
+
+/* Buttons IRQ definitions */
+
+#define MIN_IRQBUTTON     BUTTON_USER1
+#define MAX_IRQBUTTON     BUTTON_USER2
+#define NUM_IRQBUTTONS    (BUTTON_USER1 - BUTTON_USER2 + 1)
+
 int rp2040_bringup(void);
 
 #ifdef CONFIG_DEV_GPIO