stmhal: Make switch a class, to follow suit of all other modules.

Instead of pyb.switch() as a function, it's more consistent (with
respect to all the other modules and peripherals) to have
pyb.Switch() create a switch object.  This then generalises to having
multiple switches.  Call the object to get its state.  Use sw.callback
to set the callback function for when the switch is pressed.

stmhal/main.c

@@ -205,7 +205,9 @@ int main(void) {
     pendsv_init();
     timer_tim3_init();
     led_init();
+#if MICROPY_HW_HAS_SWITCH
     switch_init0();
+#endif
 
     int first_soft_reset = true;
 
@@ -297,11 +299,6 @@ soft_reset:
     pin_init();
     extint_init();
 
-#if MICROPY_HW_HAS_SWITCH
-    // must come after extint_init
-    switch_init();
-#endif
-
 #if MICROPY_HW_HAS_LCD
     // LCD init (just creates class, init hardware by calling LCD())
     lcd_init();

stmhal/modpyb.c

@@ -295,7 +295,7 @@ STATIC const mp_map_elem_t pyb_module_globals_table[] = {
 #endif
 
 #if MICROPY_HW_HAS_SWITCH
-    { MP_OBJ_NEW_QSTR(MP_QSTR_switch), (mp_obj_t)&pyb_switch_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_Switch), (mp_obj_t)&pyb_switch_type },
 #endif
 
 #if MICROPY_HW_HAS_SDCARD

stmhal/qstrdefsport.h

@@ -20,8 +20,6 @@ Q(gc)
 Q(repl_info)
 Q(delay)
 Q(udelay)
-Q(switch)
-Q(SW)
 Q(servo)
 Q(pwm)
 Q(read)
@@ -79,6 +77,10 @@ Q(off)
 Q(toggle)
 Q(intensity)
 
+// for Switch class
+Q(Switch)
+Q(callback)
+
 // for UART class
 Q(UART)
 Q(baudrate)

stmhal/usrsw.c

@@ -1,5 +1,6 @@
 #include <stdio.h>
-#include <stm32f4xx_hal.h>
+
+#include "stm32f4xx_hal.h"
 
 #include "misc.h"
 #include "mpconfig.h"
@@ -27,16 +28,6 @@
 //
 // pyb.switch(switch_pressed)
 
-static mp_obj_t switch_user_callback_obj;
-
-static mp_obj_t switch_callback(mp_obj_t line) {
-    if (switch_user_callback_obj != mp_const_none) {
-        mp_call_function_0(switch_user_callback_obj);
-    }
-    return mp_const_none;
-}
-static MP_DEFINE_CONST_FUN_OBJ_1(switch_callback_obj, switch_callback);
-
 // this function inits the switch GPIO so that it can be used
 void switch_init0(void) {
     GPIO_InitTypeDef init;
@@ -47,34 +38,80 @@ void switch_init0(void) {
     HAL_GPIO_Init(MICROPY_HW_USRSW_PIN.gpio, &init);
 }
 
-// this function inits the callback pointer
-void switch_init(void) {
-    switch_user_callback_obj = mp_const_none;
-}
-
 int switch_get(void) {
     int val = ((MICROPY_HW_USRSW_PIN.gpio->IDR & MICROPY_HW_USRSW_PIN.pin_mask) != 0);
     return val == MICROPY_HW_USRSW_PRESSED;
 }
 
 /******************************************************************************/
-/* Micro Python bindings                                                      */
+// Micro Python bindings
 
-static mp_obj_t pyb_switch(uint n_args, mp_obj_t *args) {
-    if (n_args == 0) {
+typedef struct _pyb_switch_obj_t {
+    mp_obj_base_t base;
+    mp_obj_t callback;
+} pyb_switch_obj_t;
+
+STATIC pyb_switch_obj_t pyb_switch_obj;
+
+void pyb_switch_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
+    print(env, "Switch()");
+}
+
+STATIC mp_obj_t pyb_switch_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
+    // check arguments
+    mp_arg_check_num(n_args, n_kw, 0, 0, false);
+
+    // init the switch object
+    pyb_switch_obj.base.type = &pyb_switch_type;
+
+    // No need to clear the callback member: if it's already been set and registered
+    // with extint then we don't want to reset that behaviour.  If it hasn't been set,
+    // then no extint will be called until it is set via the callback method.
+
+    // return static switch object
+    return (mp_obj_t)&pyb_switch_obj;
+}
+
+mp_obj_t pyb_switch_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
+    // get switch state
+    mp_arg_check_num(n_args, n_kw, 0, 0, false);
     return switch_get() ? mp_const_true : mp_const_false;
-    } else {
-        switch_user_callback_obj = args[0];
+}
+
+STATIC mp_obj_t switch_callback(mp_obj_t line) {
+    if (pyb_switch_obj.callback != mp_const_none) {
+        mp_call_function_0(pyb_switch_obj.callback);
+    }
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(switch_callback_obj, switch_callback);
+
+mp_obj_t pyb_switch_callback(mp_obj_t self_in, mp_obj_t callback) {
+    pyb_switch_obj_t *self = self_in;
+    self->callback = callback;
     // Init the EXTI each time this function is called, since the EXTI
     // may have been disabled by an exception in the interrupt, or the
     // user disabling the line explicitly.
     extint_register((mp_obj_t)&MICROPY_HW_USRSW_PIN,
                     MICROPY_HW_USRSW_EXTI_MODE,
                     MICROPY_HW_USRSW_PULL,
-                        switch_user_callback_obj == mp_const_none ? mp_const_none : (mp_obj_t)&switch_callback_obj,
+                    callback == mp_const_none ? mp_const_none : (mp_obj_t)&switch_callback_obj,
                     true, NULL);
     return mp_const_none;
-    }
 }
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_switch_callback_obj, pyb_switch_callback);
 
-MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_switch_obj, 0, 1, pyb_switch);
+STATIC const mp_map_elem_t pyb_switch_locals_dict_table[] = {
+    { MP_OBJ_NEW_QSTR(MP_QSTR_callback), (mp_obj_t)&pyb_switch_callback_obj },
+};
+
+STATIC MP_DEFINE_CONST_DICT(pyb_switch_locals_dict, pyb_switch_locals_dict_table);
+
+const mp_obj_type_t pyb_switch_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_Switch,
+    .print = pyb_switch_print,
+    .make_new = pyb_switch_make_new,
+    .call = pyb_switch_call,
+    .locals_dict = (mp_obj_t)&pyb_switch_locals_dict,
+};

stmhal/usrsw.h

@@ -1,5 +1,4 @@
 void switch_init0(void);
-void switch_init(void);
 int switch_get(void);
 
-MP_DECLARE_CONST_FUN_OBJ(pyb_switch_obj);
+extern const mp_obj_type_t pyb_switch_type;