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68 lines
2.0 KiB
68 lines
2.0 KiB
4 months ago
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/* devmem.c - Access physical addresses
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*
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* Copyright 2019 The Android Open Source Project
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USE_DEVMEM(NEWTOY(devmem, "<1>3", TOYFLAG_USR|TOYFLAG_BIN))
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config DEVMEM
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bool "devmem"
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default y
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help
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usage: devmem ADDR [WIDTH [DATA]]
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Read/write physical address. WIDTH is 1, 2, 4, or 8 bytes (default 4).
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Prefix ADDR with 0x for hexadecimal, output is in same base as address.
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*/
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#define FOR_devmem
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#include "toys.h"
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void devmem_main(void)
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{
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int writing = toys.optc == 3, page_size = sysconf(_SC_PAGESIZE), bytes = 4,fd;
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unsigned long long data = 0, map_off, map_len;
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unsigned long addr = atolx(*toys.optargs);
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void *map, *p;
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// WIDTH?
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if (toys.optc>1) {
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int i;
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if ((i=stridx("1248", *toys.optargs[1]))==-1 || toys.optargs[1][1])
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error_exit("bad width: %s", toys.optargs[1]);
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bytes = 1<<i;
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}
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// DATA? Report out of range values as errors rather than truncating.
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if (writing) data = atolx_range(toys.optargs[2], 0, (1ULL<<(8*bytes))-1);
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// Map in just enough.
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if (CFG_TOYBOX_FORK) {
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fd = xopen("/dev/mem", (writing ? O_RDWR : O_RDONLY) | O_SYNC);
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map_off = addr & ~(page_size - 1);
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map_len = (addr+bytes-map_off);
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map = xmmap(0, map_len, writing ? PROT_WRITE : PROT_READ, MAP_SHARED, fd,
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map_off);
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p = map + (addr & (page_size - 1));
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close(fd);
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} else p = (void *)addr;
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// Not using peek()/poke() because registers care about size of read/write
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if (writing) {
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if (bytes == 1) *(unsigned char *)p = data;
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else if (bytes == 2) *(unsigned short *)p = data;
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else if (bytes == 4) *(unsigned int *)p = data;
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else if (bytes == 8) *(unsigned long long *)p = data;
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} else {
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if (bytes == 1) data = *(unsigned char *)p;
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else if (bytes == 2) data = *(unsigned short *)p;
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else if (bytes == 4) data = *(unsigned int *)p;
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else if (bytes == 8) data = *(unsigned long long *)p;
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printf((!strchr(*toys.optargs, 'x')) ? "%0*lld\n" : "0x%0*llx\n",
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bytes*2, data);
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}
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if (CFG_TOYBOX_FORK) munmap(map, map_len);
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}
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