Adds support for Adafruit Trinket M0

hw/bsp/samd21/boards/trinket_m0/board.h

@@ -0,0 +1,34 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Jean Gressmann <jean@0x42.de>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ */
+
+#pragma once
+
+// LED
+#define LED_PIN               10 // PA10
+#define LED_STATE_ON          1
+
+// UART
+#define UART_SERCOM           0
+

hw/bsp/samd21/boards/trinket_m0/board.mk

@@ -0,0 +1,5 @@
+CFLAGS += -D__SAMD21E18A__ -DCFG_EXAMPLE_VIDEO_READONLY
+
+# All source paths should be relative to the top level.
+LD_FILE = $(BOARD_PATH)/trinket_m0.ld
+

hw/bsp/samd21/boards/trinket_m0/trinket_m0.ld

@@ -0,0 +1,146 @@
+/**
+ * \file
+ *
+ * \brief Linker script for running in internal FLASH on the SAMD21G18A
+ *
+ * Copyright (c) 2017 Microchip Technology Inc.
+ *
+ * \asf_license_start
+ *
+ * \page License
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the Licence at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * \asf_license_stop
+ *
+ */
+
+
+OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
+OUTPUT_ARCH(arm)
+SEARCH_DIR(.)
+
+/* Memory Spaces Definitions */
+MEMORY
+{
+  rom      (rx)  : ORIGIN = 0x00000000 + 8K, LENGTH = 0x00040000 - 8K
+  ram      (rwx) : ORIGIN = 0x20000000, LENGTH = 0x00008000
+}
+
+/* The stack size used by the application. NOTE: you need to adjust according to your application. */
+STACK_SIZE = DEFINED(STACK_SIZE) ? STACK_SIZE : DEFINED(__stack_size__) ? __stack_size__ : 0x2000;
+
+ENTRY(Reset_Handler)
+
+/* Section Definitions */
+SECTIONS
+{
+    .text :
+    {
+        . = ALIGN(4);
+        _sfixed = .;
+        KEEP(*(.vectors .vectors.*))
+        *(.text .text.* .gnu.linkonce.t.*)
+        *(.glue_7t) *(.glue_7)
+        *(.rodata .rodata* .gnu.linkonce.r.*)
+        *(.ARM.extab* .gnu.linkonce.armextab.*)
+
+        /* Support C constructors, and C destructors in both user code
+           and the C library. This also provides support for C++ code. */
+        . = ALIGN(4);
+        KEEP(*(.init))
+        . = ALIGN(4);
+        __preinit_array_start = .;
+        KEEP (*(.preinit_array))
+        __preinit_array_end = .;
+
+        . = ALIGN(4);
+        __init_array_start = .;
+        KEEP (*(SORT(.init_array.*)))
+        KEEP (*(.init_array))
+        __init_array_end = .;
+
+        . = ALIGN(4);
+        KEEP (*crtbegin.o(.ctors))
+        KEEP (*(EXCLUDE_FILE (*crtend.o) .ctors))
+        KEEP (*(SORT(.ctors.*)))
+        KEEP (*crtend.o(.ctors))
+
+        . = ALIGN(4);
+        KEEP(*(.fini))
+
+        . = ALIGN(4);
+        __fini_array_start = .;
+        KEEP (*(.fini_array))
+        KEEP (*(SORT(.fini_array.*)))
+        __fini_array_end = .;
+
+        KEEP (*crtbegin.o(.dtors))
+        KEEP (*(EXCLUDE_FILE (*crtend.o) .dtors))
+        KEEP (*(SORT(.dtors.*)))
+        KEEP (*crtend.o(.dtors))
+
+        . = ALIGN(4);
+        _efixed = .;            /* End of text section */
+    } > rom
+
+    /* .ARM.exidx is sorted, so has to go in its own output section.  */
+    PROVIDE_HIDDEN (__exidx_start = .);
+    .ARM.exidx :
+    {
+      *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+    } > rom
+    PROVIDE_HIDDEN (__exidx_end = .);
+
+    . = ALIGN(4);
+    _etext = .;
+
+    .relocate : AT (_etext)
+    {
+        . = ALIGN(4);
+        _srelocate = .;
+        *(.ramfunc .ramfunc.*);
+        *(.data .data.*);
+        . = ALIGN(4);
+        _erelocate = .;
+    } > ram
+
+    /* .bss section which is used for uninitialized data */
+    .bss (NOLOAD) :
+    {
+        . = ALIGN(4);
+        _sbss = . ;
+        _szero = .;
+        *(.bss .bss.*)
+        *(COMMON)
+        . = ALIGN(4);
+        _ebss = . ;
+        _ezero = .;
+        end = .;
+    } > ram
+
+    /* stack section */
+    .stack (NOLOAD):
+    {
+        . = ALIGN(8);
+        _sstack = .;
+        . = . + STACK_SIZE;
+        . = ALIGN(8);
+        _estack = .;
+    } > ram
+
+    . = ALIGN(4);
+    _end = . ;
+}

hw/bsp/samd21/family.c

@@ -44,6 +44,11 @@ void USB_Handler(void)
   tud_int_handler(0);
 }
 
+//--------------------------------------------------------------------+
+// UART support
+//--------------------------------------------------------------------+
+void uart_init(void);
+
 //--------------------------------------------------------------------+
 // MACRO TYPEDEF CONSTANT ENUM DECLARATION
 //--------------------------------------------------------------------+
@@ -84,6 +89,8 @@ void board_init(void)
   gpio_set_pin_pull_mode(BUTTON_PIN, BUTTON_STATE_ACTIVE ? GPIO_PULL_DOWN : GPIO_PULL_UP);
 #endif
 
+  uart_init();
+
 #if CFG_TUSB_OS  == OPT_OS_FREERTOS
   // If freeRTOS is used, IRQ priority is limit by max syscall ( smaller is higher )
   NVIC_SetPriority(USB_IRQn, configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY);
@@ -138,6 +145,81 @@ uint32_t board_button_read(void)
 #endif
 }
 
+#if defined(UART_SERCOM)
+
+#define BOARD_SERCOM2(n)  SERCOM ## n
+#define BOARD_SERCOM(n) BOARD_SERCOM2(n)
+
+void uart_init(void)
+{
+#if UART_SERCOM == 0
+  gpio_set_pin_function(PIN_PA06, PINMUX_PA06D_SERCOM0_PAD2);
+  gpio_set_pin_function(PIN_PA07, PINMUX_PA07D_SERCOM0_PAD3);
+
+  // setup clock (48MHz)
+  _pm_enable_bus_clock(PM_BUS_APBC, SERCOM0);
+  _gclk_enable_channel(SERCOM0_GCLK_ID_CORE, GCLK_CLKCTRL_GEN_GCLK0_Val);
+
+  SERCOM0->USART.CTRLA.bit.SWRST = 1; /* reset SERCOM & enable config */
+  while(SERCOM0->USART.SYNCBUSY.bit.SWRST);
+
+  SERCOM0->USART.CTRLA.reg  =  /* CMODE = 0 -> async, SAMPA = 0, FORM = 0 -> USART frame, SMPR = 0 -> arithmetic baud rate */
+    SERCOM_USART_CTRLA_SAMPR(1) | /* 0 = 16x / arithmetic baud rate, 1 = 16x / fractional baud rate */
+//    SERCOM_USART_CTRLA_FORM(0) | /* 0 = USART Frame, 2 = LIN Master */
+    SERCOM_USART_CTRLA_DORD | /* LSB first */
+    SERCOM_USART_CTRLA_MODE(1) | /* 0 = Asynchronous, 1 = USART with internal clock */
+    SERCOM_USART_CTRLA_RXPO(3) | /* pad 3 */
+    SERCOM_USART_CTRLA_TXPO(1);  /* pad 2 */
+
+  SERCOM0->USART.CTRLB.reg =
+    SERCOM_USART_CTRLB_TXEN | /* tx enabled */
+    SERCOM_USART_CTRLB_RXEN;  /* rx enabled */
+
+  SERCOM0->USART.BAUD.reg = SERCOM_USART_BAUD_FRAC_FP(0) | SERCOM_USART_BAUD_FRAC_BAUD(26);
+
+  SERCOM0->USART.CTRLA.bit.ENABLE = 1; /* activate SERCOM */
+  while(SERCOM0->USART.SYNCBUSY.bit.ENABLE); /* wait for SERCOM to be ready */
+#endif
+}
+
+static inline void uart_send_buffer(uint8_t const *text, size_t len)
+{
+  for (size_t i = 0; i < len; ++i) {
+    BOARD_SERCOM(UART_SERCOM)->USART.DATA.reg = text[i];
+    while((BOARD_SERCOM(UART_SERCOM)->USART.INTFLAG.reg & SERCOM_USART_INTFLAG_TXC) == 0);
+  }
+}
+
+static inline void uart_send_str(const char* text)
+{
+  while (*text) {
+    BOARD_SERCOM(UART_SERCOM)->USART.DATA.reg = *text++;
+    while((BOARD_SERCOM(UART_SERCOM)->USART.INTFLAG.reg & SERCOM_USART_INTFLAG_TXC) == 0);
+  }
+}
+
+int board_uart_read(uint8_t* buf, int len)
+{
+  (void) buf; (void) len;
+  return 0;
+}
+
+int board_uart_write(void const * buf, int len)
+{
+  if (len < 0) {
+    uart_send_str(buf);
+  } else {
+    uart_send_buffer(buf, len);
+  }
+  return len;
+}
+
+#else // ! defined(UART_SERCOM)
+void uart_init(void)
+{
+
+}
+
 int board_uart_read(uint8_t* buf, int len)
 {
   (void) buf; (void) len;
@@ -149,6 +231,7 @@ int board_uart_write(void const * buf, int len)
   (void) buf; (void) len;
   return 0;
 }
+#endif
 
 #if CFG_TUSB_OS  == OPT_OS_NONE
 volatile uint32_t system_ticks = 0;