drv/button: move init function to private header

This move the pbdrv_button_init() function declaration to a private
header file. This follows the pattern used by all of the other drivers.

Author: dlech

lib/pbio/drv/button/button.h

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2022 The Pybricks Authors
+
+// Internal common button functions.
+
+#ifndef _INTERNAL_PBDRV_BUTTON_H_
+#define _INTERNAL_PBDRV_BUTTON_H_
+
+#include <pbdrv/config.h>
+
+#if PBDRV_CONFIG_BUTTON
+
+/**
+ * Initializes the low level button driver.
+ */
+void pbdrv_button_init(void);
+
+#else
+
+#define pbdrv_button_init()
+
+#endif
+
+#endif // _INTERNAL_PBDRV_BUTTON_H_

lib/pbio/drv/button/button_gpio.c

@@ -12,9 +12,7 @@
 
 #include "button_gpio.h"
 
-// PC13 is the green button (active low)
-
-void _pbdrv_button_init(void) {
+void pbdrv_button_init(void) {
     for (int i = 0; i < PBDRV_CONFIG_BUTTON_GPIO_NUM_BUTTON; i++) {
         const pbdrv_button_gpio_platform_t *platform = &pbdrv_button_gpio_platform[i];
         pbdrv_gpio_set_pull(&platform->gpio, platform->pull);

lib/pbio/drv/button/button_linux_ev3.c

@@ -17,7 +17,7 @@
 
 static int f_btn = -1; // Button file descriptor
 
-void _pbdrv_button_init(void) {
+void pbdrv_button_init(void) {
     f_btn = open("/dev/input/by-path/platform-gpio_keys-event", O_RDONLY);
     if (f_btn == -1) {
         perror("Failed to init buttons");

lib/pbio/drv/button/button_nxt.c

@@ -11,7 +11,7 @@
 
 #include <base/drivers/avr.h>
 
-void _pbdrv_button_init(void) {
+void pbdrv_button_init(void) {
 }
 
 pbio_error_t pbdrv_button_is_pressed(pbio_button_flags_t *pressed) {

lib/pbio/drv/button/button_resistor_ladder.c

@@ -11,7 +11,7 @@
 #include <pbio/button.h>
 #include <pbio/error.h>
 
-void _pbdrv_button_init(void) {
+void pbdrv_button_init(void) {
 }
 
 pbio_error_t pbdrv_button_is_pressed(pbio_button_flags_t *pressed) {

lib/pbio/drv/button/button_virtual.c

@@ -10,7 +10,7 @@
 
 #include "../virtual.h"
 
-void _pbdrv_button_init(void) {
+void pbdrv_button_init(void) {
 }
 
 pbio_error_t pbdrv_button_is_pressed(pbio_button_flags_t *pressed) {

lib/pbio/drv/core.c

@@ -7,6 +7,7 @@
 #include "battery/battery.h"
 #include "block_device/block_device.h"
 #include "bluetooth/bluetooth.h"
+#include "button/button.h"
 #include "charger/charger.h"
 #include "clock/clock.h"
 #include "counter/counter.h"
@@ -34,6 +35,7 @@ void pbdrv_init(void) {
     pbdrv_battery_init();
     pbdrv_block_device_init();
     pbdrv_bluetooth_init();
+    pbdrv_button_init();
     pbdrv_charger_init();
     pbdrv_counter_init();
     pbdrv_imu_init();

lib/pbio/include/pbdrv/button.h

@@ -20,16 +20,6 @@
 
 #if PBDRV_CONFIG_BUTTON
 
-/** @cond INTERNAL */
-
-/**
- * Initializes the low level button driver. This should be called only
- * once and must be called before using any other button functions.
- */
-void _pbdrv_button_init(void);
-
-/** @endcond */
-
 /**
  * Get bitmask indicating currently pressed buttons.
  * @param [out] pressed     Bitmask indicating which buttons are pressed
@@ -41,9 +31,6 @@ pbio_error_t pbdrv_button_is_pressed(pbio_button_flags_t *pressed);
 
 #else
 
-static inline void _pbdrv_button_init(void) {
-}
-
 static inline pbio_error_t pbdrv_button_is_pressed(pbio_button_flags_t *pressed) {
     *pressed = 0;
     return PBIO_ERROR_NOT_SUPPORTED;

lib/pbio/src/main.c

@@ -49,7 +49,6 @@ AUTOSTART_PROCESSES(
  */
 void pbio_init(void) {
     pbdrv_init();
-    _pbdrv_button_init();
     autostart_start(autostart_processes);
 }
 

lib/pbio/test/drv/button.c

@@ -12,7 +12,7 @@ void pbio_test_button_set_pressed(pbio_button_flags_t flags) {
     pbio_test_button_flags = flags;
 }
 
-void _pbdrv_button_init(void) {
+void pbdrv_button_init(void) {
 }
 
 pbio_error_t pbdrv_button_is_pressed(pbio_button_flags_t *pressed) {