SAMD51 LCD support (#15113)

Marlin/src/HAL/HAL_SAMD51/HAL.h

@@ -146,3 +146,11 @@ FORCE_INLINE void _delay_ms(const int delay_ms) { delay(delay_ms); }
 #pragma GCC diagnostic ignored "-Wunused-function"
 int freeMemory(void);
 #pragma GCC diagnostic pop
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+char *dtostrf(double __val, signed char __width, unsigned char __prec, char *__s);
+#ifdef __cplusplus
+  }
+#endif

Marlin/src/lcd/dogm/HAL_LCD_com_defines.h

@@ -60,6 +60,11 @@
     #define U8G_COM_HAL_HW_SPI_FN       u8g_com_arduino_hw_spi_fn
     #define U8G_COM_ST7920_HAL_SW_SPI   u8g_com_arduino_st7920_spi_fn
     #define U8G_COM_ST7920_HAL_HW_SPI   u8g_com_arduino_st7920_hw_spi_fn
+  #elif defined(__SAMD51__)
+    #define U8G_COM_HAL_SW_SPI_FN       u8g_com_arduino_std_sw_spi_fn
+    #define U8G_COM_HAL_HW_SPI_FN       u8g_com_samd51_hw_spi_fn
+    #define U8G_COM_ST7920_HAL_SW_SPI   u8g_com_arduino_st7920_spi_fn
+    #define U8G_COM_ST7920_HAL_HW_SPI   u8g_com_samd51_st7920_hw_spi_fn
   #else
     #define U8G_COM_HAL_SW_SPI_FN       u8g_com_arduino_std_sw_spi_fn
     #define U8G_COM_HAL_HW_SPI_FN       u8g_com_arduino_hw_spi_fn

Marlin/src/lcd/dogm/u8g_dev_st7920_128x64_HAL.cpp

@@ -202,7 +202,7 @@ u8g_dev_t u8g_dev_st7920_128x64_HAL_4x_sw_spi = { u8g_dev_st7920_128x64_HAL_4x_f
 U8G_PB_DEV(u8g_dev_st7920_128x64_HAL_hw_spi, LCD_PIXEL_WIDTH, LCD_PIXEL_HEIGHT, PAGE_HEIGHT, u8g_dev_st7920_128x64_HAL_fn, U8G_COM_ST7920_HAL_HW_SPI);
 u8g_dev_t u8g_dev_st7920_128x64_HAL_4x_hw_spi = { u8g_dev_st7920_128x64_HAL_4x_fn, &u8g_dev_st7920_128x64_HAL_4x_pb, U8G_COM_ST7920_HAL_HW_SPI };
 
-#if defined(U8G_HAL_LINKS) || defined(__SAM3X8E__)
+#if !defined(__AVR__) || defined(U8G_HAL_LINKS)
   // Also use this device for HAL version of rrd class. This results in the same device being used
   // for the ST7920 for HAL systems no matter what is selected in ultralcd_impl_DOGM.h.
   u8g_dev_t u8g_dev_st7920_128x64_rrd_sw_spi = { u8g_dev_st7920_128x64_HAL_4x_fn, &u8g_dev_st7920_128x64_HAL_4x_pb, U8G_COM_ST7920_HAL_SW_SPI };

Marlin/src/lcd/dogm/ultralcd_st7920_u8glib_rrd_AVR.cpp

@@ -23,9 +23,11 @@
 // NOTE - the HAL version of the rrd device uses a generic ST7920 device.  See the
 // file u8g_dev_st7920_128x64_HAL.cpp for the HAL version.
 
+#if defined(__AVR__) && !defined(U8G_HAL_LINKS)
+
 #include "../../inc/MarlinConfig.h"
 
-#if ENABLED(U8GLIB_ST7920) && !defined(U8G_HAL_LINKS) && !defined(__SAM3X8E__)
+#if ENABLED(U8GLIB_ST7920)
 
 #include "ultralcd_st7920_u8glib_rrd_AVR.h"
 
@@ -149,4 +151,5 @@ u8g_dev_t u8g_dev_st7920_128x64_rrd_sw_spi = {u8g_dev_rrd_st7920_128x64_fn, &u8g
   void ST7920_write_byte(const uint8_t val) { ST7920_WRITE_BYTE(val); }
 #endif
 
-#endif // U8GLIB_ST7920 && !U8G_HAL_LINKS && !__SAM3X8E__
+#endif // U8GLIB_ST7920
+#endif // __AVR__ && !U8G_HAL_LINKS

Marlin/src/lcd/dogm/ultralcd_st7920_u8glib_rrd_AVR.h

@@ -25,9 +25,6 @@
 // file u8g_dev_st7920_128x64_HAL.cpp for the HAL version.
 
 #include "../../inc/MarlinConfig.h"
-
-#if ENABLED(U8GLIB_ST7920) && !defined(U8G_HAL_LINKS) && !defined(__SAM3X8E__)
-
 #include "../../HAL/shared/Delay.h"
 
 #define ST7920_CLK_PIN  LCD_PINS_D4
@@ -94,5 +91,3 @@ void ST7920_SWSPI_SND_8BIT(uint8_t val);
 #define ST7920_SET_DAT()         { ST7920_SWSPI_SND_8BIT(0xFA); U8G_DELAY(); }
 #define ST7920_WRITE_BYTE(a)     { ST7920_SWSPI_SND_8BIT((uint8_t)((a)&0xF0u)); ST7920_SWSPI_SND_8BIT((uint8_t)((a)<<4u)); U8G_DELAY(); }
 #define ST7920_WRITE_BYTES(p,l)  { for (uint8_t i = l + 1; --i;) { ST7920_SWSPI_SND_8BIT(*p&0xF0); ST7920_SWSPI_SND_8BIT(*p<<4); p++; } U8G_DELAY(); }
-
-#endif // U8GLIB_ST7920 && !U8G_HAL_LINKS && !__SAM3X8E__