Function cbmem_devmem_init

util/cbmem/devmem_drv.c:354–430

#endif /* defined(__arm__) || defined(__aarch64__) */

bool cbmem_devmem_init(bool writeable)
{
	mem_fd = open("/dev/mem", writeable ? O_RDWR : O_RDONLY, 0);
	if (mem_fd < 0) {
		fprintf(stderr, "Failed to gain memory access: %s\n", strerror(errno));
		return false;
	}

#if defined(__arm__) || defined(__aarch64__)
	int addr_cells, size_cells;
	char *coreboot_node =
		dt_find_compat("/proc/device-tree", "coreboot", &addr_cells, &size_cells);

	if (!coreboot_node) {
		fprintf(stderr, "Could not find 'coreboot' compatible node!\n");
		return false;
	}

	if (addr_cells < 0) {
		fprintf(stderr, "Warning: no #address-cells node in tree!\n");
		addr_cells = 1;
	}

	int nlen = strlen(coreboot_node);
	char *reg = alloca(nlen + sizeof("/reg"));

	strcpy(reg, coreboot_node);
	strcpy(reg + nlen, "/reg");
	free(coreboot_node);

	int fd = open(reg, O_RDONLY);
	if (fd < 0) {
		perror(reg);
		return false;
	}

	int i;
	size_t size_to_read = addr_cells * 4 + size_cells * 4;
	uint8_t *dtbuffer = alloca(size_to_read);
	if (read(fd, dtbuffer, size_to_read) < 0) {
		perror(reg);
		return false;
	}
	close(fd);

	/* No variable-length byte swap function anywhere in C... how sad. */
	uint64_t baseaddr = 0;
	for (i = 0; i < addr_cells * 4; i++) {
		baseaddr <<= 8;
		baseaddr |= *dtbuffer;
		dtbuffer++;
	}
	uint64_t cb_table_size = 0;
	for (i = 0; i < size_cells * 4; i++) {
		cb_table_size <<= 8;
		cb_table_size |= *dtbuffer;
		dtbuffer++;
	}