From dd3695fad0ea8b6f46afc59e881ace932202104b Mon Sep 17 00:00:00 2001
From: Jan-Derk Bakker <J.D.Bakker@its.tudelft.nl>
Date: Wed, 7 Sep 2016 16:26:03 -0500
Subject: Initial import of stock devmem2 program from
 http://free-electrons.com/pub/mirror/devmem2.c

---
 devmem-aspeed.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 devmem-aspeed.c

diff --git a/devmem-aspeed.c b/devmem-aspeed.c
new file mode 100644
index 0000000..7732ecb
--- /dev/null
+++ b/devmem-aspeed.c
@@ -0,0 +1,131 @@
+/*
+ * devmem2.c: Simple program to read/write from/to any location in memory.
+ *
+ *  Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
+ *
+ *
+ * This software has been developed for the LART computing board
+ * (http://www.lart.tudelft.nl/). The development has been sponsored by
+ * the Mobile MultiMedia Communications (http://www.mmc.tudelft.nl/)
+ * and Ubiquitous Communications (http://www.ubicom.tudelft.nl/)
+ * projects.
+ *
+ * The author can be reached at:
+ *
+ *  Jan-Derk Bakker
+ *  Information and Communication Theory Group
+ *  Faculty of Information Technology and Systems
+ *  Delft University of Technology
+ *  P.O. Box 5031
+ *  2600 GA Delft
+ *  The Netherlands
+ *
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <termios.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+  
+#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \
+  __LINE__, __FILE__, errno, strerror(errno)); exit(1); } while(0)
+ 
+#define MAP_SIZE 4096UL
+#define MAP_MASK (MAP_SIZE - 1)
+
+int main(int argc, char **argv) {
+    int fd;
+    void *map_base, *virt_addr; 
+	unsigned long read_result, writeval;
+	off_t target;
+	int access_type = 'w';
+	
+	if(argc < 2) {
+		fprintf(stderr, "\nUsage:\t%s { address } [ type [ data ] ]\n"
+			"\taddress : memory address to act upon\n"
+			"\ttype    : access operation type : [b]yte, [h]alfword, [w]ord\n"
+			"\tdata    : data to be written\n\n",
+			argv[0]);
+		exit(1);
+	}
+	target = strtoul(argv[1], 0, 0);
+
+	if(argc > 2)
+		access_type = tolower(argv[2][0]);
+
+
+    if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) FATAL;
+    printf("/dev/mem opened.\n"); 
+    fflush(stdout);
+    
+    /* Map one page */
+    map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~MAP_MASK);
+    if(map_base == (void *) -1) FATAL;
+    printf("Memory mapped at address %p.\n", map_base); 
+    fflush(stdout);
+    
+    virt_addr = map_base + (target & MAP_MASK);
+    switch(access_type) {
+		case 'b':
+			read_result = *((unsigned char *) virt_addr);
+			break;
+		case 'h':
+			read_result = *((unsigned short *) virt_addr);
+			break;
+		case 'w':
+			read_result = *((unsigned long *) virt_addr);
+			break;
+		default:
+			fprintf(stderr, "Illegal data type '%c'.\n", access_type);
+			exit(2);
+	}
+    printf("Value at address 0x%X (%p): 0x%X\n", target, virt_addr, read_result); 
+    fflush(stdout);
+
+	if(argc > 3) {
+		writeval = strtoul(argv[3], 0, 0);
+		switch(access_type) {
+			case 'b':
+				*((unsigned char *) virt_addr) = writeval;
+				read_result = *((unsigned char *) virt_addr);
+				break;
+			case 'h':
+				*((unsigned short *) virt_addr) = writeval;
+				read_result = *((unsigned short *) virt_addr);
+				break;
+			case 'w':
+				*((unsigned long *) virt_addr) = writeval;
+				read_result = *((unsigned long *) virt_addr);
+				break;
+		}
+		printf("Written 0x%X; readback 0x%X\n", writeval, read_result); 
+		fflush(stdout);
+	}
+	
+	if(munmap(map_base, MAP_SIZE) == -1) FATAL;
+    close(fd);
+    return 0;
+}
+
-- 
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