samd/boards: Add generic SAMD51x20 board definitions.

The definition uses the internal oscillator for clock and only internal
flash for the file system.

It works at SAMD51J20 device as well, only that fewer pins are accessible.

Tested with a SAMD51J20 board.

Signed-off-by: robert-hh <robert@hammelrath.com>

ports/samd/boards/SAMD_GENERIC_D51X20/board.json

@@ -0,0 +1,16 @@
+{
+    "deploy": [
+        "../deploy.md"
+    ],
+    "docs": "",
+    "features": [
+        "USB"
+    ],
+    "images": [
+        "generic_board.jpg"
+    ],
+    "mcu": "samd51",
+    "vendor": "Microchip",
+    "product": "Generic SAMD51P20",
+    "thumbnail": ""
+}

ports/samd/boards/SAMD_GENERIC_D51X20/board.md

@@ -0,0 +1,4 @@
+The following firmware should work on most boards with a
+SAMD51J20 and SAMD51P20 MCU. It uses only the features built into
+the MCU. Additional devices at the board like external flash
+are not supported.

ports/samd/boards/SAMD_GENERIC_D51X20/mpconfigboard.h

@@ -0,0 +1,2 @@
+#define MICROPY_HW_BOARD_NAME "Generic SAMD51P20"
+#define MICROPY_HW_MCU_NAME   "SAMD51P20A"

ports/samd/boards/SAMD_GENERIC_D51X20/mpconfigboard.mk

@@ -0,0 +1,13 @@
+MCU_SERIES = SAMD51
+CMSIS_MCU = SAMD51P20A
+LD_FILES = boards/samd51x19a.ld sections.ld
+TEXT0 = 0x4000
+
+
+# The ?='s allow overriding in mpconfigboard.mk.
+# MicroPython settings
+# The size of a MCU flash filesystem will be
+# 1008k - MICROPY_HW_CODESIZE - MICROPY_HW_VFSROMSIZE
+# The default for MICROPY_HW_VFSROMSIZE is 64K
+MICROPY_HW_CODESIZE ?= 752K
+MICROPY_HW_VFSROMSIZE ?= 128K

ports/samd/boards/SAMD_GENERIC_D51X20/pins.csv

@@ -0,0 +1,17 @@
+# The lines contain pairs of Pin name and Pin number.
+# Pin names must be valid Python identifiers.
+# Pin numbers have the form Pxnn, with x being A, B, C or D.
+# Lines starting with # or empty lines are ignored.
+
+USB_DM,PA24
+USB_DP,PA25
+
+QSPI_CS,PB11
+QSPI_SCK,PB10
+QSPI_D0,PA08
+QSPI_D1,PA09
+QSPI_D2,PA10
+QSPI_D3,PA11
+
+SWCLK,PA30
+SWDIO,PA31