sharpdisplay: Prevent 'ValueError: <pin> in use' exception

.. when constructing the SPI bus again after reset.

Testing performed: on nRF52840, that these sequences would work
repeatedly when soft-resetting in between invocations:
```
import displayio, board, sharpdisplay
displayio.release_displays()
bus = board.SPI()
framebuffer = sharpdisplay.SharpMemoryFramebuffer(bus, board.D2, 400, 240)
```
and
```
import displayio, board, sharpdisplay, busio
displayio.release_displays()
bus = busio.SPI(board.SCK, MOSI=board.MOSI)
framebuffer = sharpdisplay.SharpMemoryFramebuffer(bus, board.D2, 400, 240)
```
.. and that an actual demo would work across soft resets as well.

This feels a bit ad-hoc.  Better would be to make "never reset bus" be
a counted thing and add some "un-never-resets" in the right spots.  An
area for future improvement.

Author: jepler

shared-bindings/sharpdisplay/SharpMemoryFramebuffer.c

@@ -71,7 +71,7 @@ STATIC mp_int_t sharpdisplay_framebuffer_get_buffer(mp_obj_t self_in, mp_buffer_
 
 STATIC mp_obj_t sharpdisplay_framebuffer_deinit(mp_obj_t self_in) {
     sharpdisplay_framebuffer_obj_t *self = (sharpdisplay_framebuffer_obj_t*)self_in;
-    common_hal_sharpdisplay_framebuffer_deinit(self);
+    common_hal_sharpdisplay_framebuffer_deinit(self, false);
 
     return mp_const_none;
 }

shared-module/board/__init__.c

@@ -39,6 +39,11 @@
 #include "shared-module/displayio/__init__.h"
 #endif
 
+#if CIRCUITPY_SHARPDISPLAY
+#include "shared-bindings/sharpdisplay/SharpMemoryFramebuffer.h"
+#include "shared-module/sharpdisplay/SharpMemoryFramebuffer.h"
+#endif
+
 #if BOARD_I2C
 // Statically allocate the I2C object so it can live past the end of the heap and into the next VM.
 // That way it can be used by built-in I2CDisplay displays and be accessible through board.I2C().
@@ -152,9 +157,16 @@ void reset_board_busses(void) {
             display_using_spi = true;
             break;
         }
+        #if CIRCUITPY_SHARPDISPLAY
+        if (displays[i].sharpdisplay.bus == spi_singleton) {
+            display_using_spi = true;
+            break;
+        }
+        #endif
     }
     #endif
     if (!display_using_spi) {
+        common_hal_busio_spi_deinit(spi_singleton);
         spi_singleton = NULL;
     }
 #endif

shared-module/displayio/__init__.c

@@ -113,7 +113,7 @@ void common_hal_displayio_release_displays(void) {
 #endif
 #if CIRCUITPY_SHARPDISPLAY
         } else if (displays[i].bus_base.type == &sharpdisplay_framebuffer_type) {
-            common_hal_sharpdisplay_framebuffer_deinit(&displays[i].sharpdisplay);
+            common_hal_sharpdisplay_framebuffer_deinit(&displays[i].sharpdisplay, false);
 #endif
         }
         displays[i].fourwire_bus.base.type = &mp_type_NoneType;
@@ -189,7 +189,7 @@ void reset_displays(void) {
             if(any_display_uses_this_framebuffer(&sharp->base)) {
                 common_hal_sharpdisplay_framebuffer_reset(sharp);
             } else {
-                common_hal_sharpdisplay_framebuffer_deinit(sharp);
+                common_hal_sharpdisplay_framebuffer_deinit(sharp, true);
             }
 #endif
         } else {

shared-module/sharpdisplay/SharpMemoryFramebuffer.c

@@ -127,12 +127,12 @@ void common_hal_sharpdisplay_framebuffer_get_bufinfo(sharpdisplay_framebuffer_ob
     *bufinfo = self->bufinfo;
 }
 
-void common_hal_sharpdisplay_framebuffer_deinit(sharpdisplay_framebuffer_obj_t *self) {
+void common_hal_sharpdisplay_framebuffer_deinit(sharpdisplay_framebuffer_obj_t *self, bool from_reset) {
     if (self->base.type != &sharpdisplay_framebuffer_type) {
         return;
     }
 
-    if (self->bus == &self->inline_bus) {
+    if (from_reset || self->bus == &self->inline_bus) {
         common_hal_busio_spi_deinit(self->bus);
     }
 
@@ -208,7 +208,7 @@ void common_hal_sharpdisplay_framebuffer_swapbuffers(sharpdisplay_framebuffer_ob
 
 STATIC void sharpdisplay_framebuffer_deinit(mp_obj_t self_in) {
     sharpdisplay_framebuffer_obj_t *self = self_in;
-    common_hal_sharpdisplay_framebuffer_deinit(self);
+    common_hal_sharpdisplay_framebuffer_deinit(self, false);
 }
 
 STATIC void sharpdisplay_framebuffer_get_bufinfo(mp_obj_t self_in, mp_buffer_info_t *bufinfo) {

shared-module/sharpdisplay/SharpMemoryFramebuffer.h

@@ -47,7 +47,7 @@ typedef struct {
 
 void common_hal_sharpdisplay_framebuffer_construct(sharpdisplay_framebuffer_obj_t *self, busio_spi_obj_t *spi, mcu_pin_obj_t *chip_select, int baudrate, int width, int height);
 void common_hal_sharpdisplay_framebuffer_swap_buffers(sharpdisplay_framebuffer_obj_t *self, uint8_t *dirty_row_bitmask);
-void common_hal_sharpdisplay_framebuffer_deinit(sharpdisplay_framebuffer_obj_t *self);
+void common_hal_sharpdisplay_framebuffer_deinit(sharpdisplay_framebuffer_obj_t *self, bool from_reset);
 void common_hal_sharpdisplay_framebuffer_get_bufinfo(sharpdisplay_framebuffer_obj_t *self, mp_buffer_info_t *bufinfo);
 int common_hal_sharpdisplay_framebuffer_get_height(sharpdisplay_framebuffer_obj_t *self);
 int common_hal_sharpdisplay_framebuffer_get_width(sharpdisplay_framebuffer_obj_t *self);