cpu/fe310: Use newlib_syscalls_default stub implementations

This switches the fe310 to use the common newlib_syscalls_default
implementation.

cpu/fe310/Makefile

@@ -4,8 +4,4 @@ MODULE = cpu
 # add a list of subdirectories, that should also be built
 DIRS = periph vendor
 
-ifneq (1,$(PICOLIBC))
-  DIRS += nano
-endif
-
 include $(RIOTBASE)/Makefile.base

cpu/fe310/Makefile.dep

@@ -2,7 +2,7 @@ ifneq (,$(filter picolibc,$(FEATURES_USED)))
   USEMODULE += picolibc
 else
   USEMODULE += newlib_nano
-  USEMODULE += newlib_syscalls_fe310
+  USEMODULE += newlib_syscalls_default
 endif
 
 USEMODULE += sifive_drivers_fe310

cpu/fe310/cpu.c

@@ -115,10 +115,6 @@ void cpu_init(void)
 
     /* Initialize stdio */
     stdio_init();
-#ifndef _PICOLIBC__
-    /* Initialize newlib-nano library stubs */
-    nanostubs_init();
-#endif /* PICOLIBC */
 
     /* Initialize static peripheral */
     periph_init();

cpu/fe310/nano/Makefile

@@ -1,3 +0,0 @@
-MODULE = newlib_syscalls_fe310
-
-include $(RIOTBASE)/Makefile.base

cpu/fe310/nano/nanostubs.c

@@ -1,176 +0,0 @@
-/*
- * Copyright (C) 2017 Ken Rabold
- *
- * This file is subject to the terms and conditions of the GNU Lesser
- * General Public License v2.1. See the file LICENSE in the top level
- * directory for more details.
- */
-
-/**
- * @ingroup     cpu_fe310
- * @{
- *
- * @file        nanostubs.c
- * @brief       Implementation of the Newlib-nano for SiFive FE310
- *
- * @author      Ken Rabold
- * @}
- */
-
-#include <reent.h>
-#include <errno.h>
-#include <stdio.h>
-#include <sys/stat.h>
-#include <sys/unistd.h>
-
-#include "sched.h"
-#include "thread.h"
-#include "irq.h"
-#include "cpu.h"
-#include "stdio_uart.h"
-
-extern char _sheap;            /* Heap markers from fe310.ld file */
-extern char _eheap;
-char *heap_top = &_sheap + 4;
-
-/**
- * @brief Initialize the Newlib-nano functions (also forces inclusion of stubs for linking)
- */
-void nanostubs_init(void)
-{
-#if defined(MODULE_STDIO_UART)
-    /* STDIO redirected to UART, no line buffering */
-    setvbuf(stdout, NULL, _IONBF, 0);
-#endif
-}
-
-void _init(void)
-{
-}
-
-void _fini(void)
-{
-}
-
-void *_sbrk(ptrdiff_t incr)
-{
-    unsigned int state = irq_disable();
-    void *res = heap_top;
-
-    /* Allocate memory from heap */
-    if ((heap_top + incr > &_eheap) || (heap_top + incr < &_sheap)) {
-        errno = ENOMEM;
-        res = (void *) -1;
-    }
-    else {
-        heap_top += incr;
-    }
-
-    irq_restore(state);
-    return res;
-}
-
-int _open(const char *name, int flags, int mode)
-{
-    (void) name;
-    (void) flags;
-    (void) mode;
-    errno = ENODEV;
-    return -1;
-}
-
-_ssize_t _read(int fd, void *buffer, size_t count)
-{
-#if defined(MODULE_STDIO_UART)
-    if (fd == STDIN_FILENO) {
-        return stdio_read(buffer, count);
-    }
-    errno = EBADF;
-    return -1;
-#else
-    (void) fd;
-    (void) buffer;
-    (void) count;
-    errno = ENODEV;
-    return -1;
-#endif
-}
-
-_ssize_t _write(int fd, const void *data, size_t count)
-{
-#if defined(MODULE_STDIO_UART)
-    if (fd == STDOUT_FILENO || fd == STDERR_FILENO) {
-        return stdio_write(data, count);
-    }
-    errno = EBADF;
-    return -1;
-#else
-    (void) fd;
-    (void) data;
-    (void) count;
-    errno = ENODEV;
-    return -1;
-#endif
-}
-
-int _close(int fd)
-{
-    (void) fd;
-    errno = ENODEV;
-    return -1;
-}
-
-int _isatty(int fd)
-{
-    errno = 0;
-
-    if (fd == STDIN_FILENO || fd == STDOUT_FILENO || fd == STDERR_FILENO) {
-        return 1;
-    }
-
-    return 0;
-}
-
-int _fstat(int fd, struct stat *st)
-{
-    (void) fd;
-    (void) st;
-    errno = ENODEV;
-    return -1;
-}
-
-_off_t _lseek(int fd, _off_t pos, int dir)
-{
-    (void) fd;
-    (void) pos;
-    (void) dir;
-    errno = ENODEV;
-    return -1;
-}
-
-int _gettimeofday(struct timeval *tp, void *tzp)
-{
-    (void) tp;
-    (void) tzp;
-    errno = EINVAL;
-    return -1;
-}
-
-int _getpid(void)
-{
-    return thread_getpid();
-}
-
-int _kill(int pid, int sig)
-{
-    (void) pid;
-    (void) sig;
-    errno = EINVAL;
-    return -1;
-}
-
-void _exit(int _status)
-{
-    (void) _status;
-    while(1);
-}