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/*
* Copyright (C) 2021 Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
*
* 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 3 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, see <https://www.gnu.org/licenses/>.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "memory.h"
struct memory_mapping {
unsigned int *mmap_phys_base;
unsigned int *mmap_virt_base;
unsigned int mmap_length;
};
static bool addr_is_valid(struct memory_mapping *memory_mapping,
unsigned int *addr)
{
if (addr < memory_mapping->mmap_phys_base)
return false;
if (addr > (memory_mapping->mmap_phys_base + memory_mapping->mmap_length))
return false;
return true;
}
int init_memory_mapping(int debug, struct memory_mapping *memory_mapping,
off_t addr, size_t length)
{
int fd;
int rc;
char *devmem = "/dev/mem";
fd = open(devmem, O_RDWR | O_SYNC);
if (fd == -1) {
rc = errno;
printf("%s: opening %s failed with error %d: %s\n",
__func__, devmem, rc, strerror(rc));
return -1;
}
memory_mapping->mmap_virt_base = mmap(0, length, PROT_READ|PROT_WRITE,
MAP_SHARED, fd, addr);
if (memory_mapping->mmap_virt_base == MAP_FAILED) {
rc = errno;
printf("%s: mmap on %s failed with error %d: %s\n",
__func__, devmem, rc, strerror(rc));
return -1;
}
rc = close(fd);
if (rc == -1) {
rc = errno;
printf("Closing %s failed with error %d: %s\n",
devmem, rc, strerror(rc));
return -1;
}
if (debug)
printf("%s: mapped address 0 @ %p\n", __func__,
memory_mapping->mmap_virt_base);
return 0;
}
int read_word(int debug, struct memory_mapping *memory_mapping,
unsigned int addr, unsigned int *result)
{
unsigned int *virt_addr;
if (!addr_is_valid(memory_mapping, (unsigned int *)addr))
return -EDOM;
virt_addr = memory_mapping->mmap_virt_base + addr;
*result = *virt_addr;
if (debug)
printf("%s: debug=%d, addr=0x%x, result=0x%x\n",
__func__, debug, addr, *result);
return 0;
}
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