Add RISC-V 32 IMAC support.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

entry-riscv32.c

@@ -0,0 +1,84 @@
+/*
+ * entry-riscv32.c - Entry routine when reset.
+ *
+ * Copyright (C) 2019
+ *               Flying Stone Technology
+ * Author: NIIBE Yutaka <gniibe@fsij.org>
+ *
+ * This file is a part of Chopstx, a thread library for embedded.
+ *
+ * Chopstx is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chopstx is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * As additional permission under GNU GPL version 3 section 7, you may
+ * distribute non-source form of the Program without the copy of the
+ * GNU GPL normally required by section 4, provided you inform the
+ * recipients of GNU GPL by a written offer.
+ *
+ */
+
+#include "board.h"
+#include "mcu/clk_gpio_init-gd32vf103.c"
+
+/*
+ * Startup entry point.
+ */
+void __attribute__ ((naked,section(".text.startup.0")))
+entry (void)
+{
+  /* Start at 0x00000000 (alias 0x08000000), interrupt masked */
+  asm volatile (
+	"li	a0,0x0800000c\n\t"
+        "jr	a0\n\t"		/* Jump to physical address */
+        ".align	2\n\t"
+    ".option push\n"
+    ".option norelax\n\t"
+	"la	gp,__global_pointer$\n"
+    ".option pop\n\t"
+	"la	sp,__main_stack_end__\n\t"
+	"call	clock_init\n\t"
+	/* Clear BSS section.  */
+	"la	a0,_bss_start\n\t"
+	"la	a1,_bss_end\n\t"
+    "0:\n\t"
+	"beq	a0,a1,1f\n"
+	"sw	zero,(a0)\n\t"
+	"addi	a0,a0,4\n\t"
+	"j	0b\n"
+    "1:\n\t"
+	/* Copy data section.  */
+	"la	a0,_textdata\n\t"
+	"la	a1,_data\n\t"
+	"la	a2,_edata\n"
+    "0:\n\t"
+	"beq	a1,a2,1f\n\t"
+	"lw	t0,(a0)\n\t"
+	"sw	t0,(a1)\n\t"
+	"addi	a0,a0,4\n\t"
+	"addi	a1,a1,4\n\t"
+	"j	0b\n"
+    "1:\n\t"
+	/* Switch to application stack.  */
+	"la	sp,__process0_stack_end__-160\n\t"
+	"mv	a0,sp\n\t"
+	"call	chx_init\n\t"
+	"call	chx_systick_init\n\t"
+	"call	gpio_init\n\t"
+	/* Enable interrupts.  */
+	"csrsi	mstatus,8\n\t"
+	/* Call main.  */
+	"call	main\n\t"
+    "3:\n\t"
+	"j	3b"
+	: /* no output */ : /* no input */ : "memory");
+}