1 files changed, 128 insertions, 0 deletions
diff --git a/release/src/router/busybox/miscutils/devmem.c b/release/src/router/busybox/miscutils/devmem.c
new file mode 100644
index 00000000..e13dedc0
--- /dev/null
+++ b/release/src/router/busybox/miscutils/devmem.c
@@ -0,0 +1,128 @@
+/*
+ * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ *  Copyright (C) 2000, Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
+ *  Copyright (C) 2008, BusyBox Team. -solar 4/26/08
+ */
+
+#include "libbb.h"
+
+int devmem_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int devmem_main(int argc UNUSED_PARAM, char **argv)
+{
+	void *map_base, *virt_addr;
+	uint64_t read_result;
+	uint64_t writeval = writeval; /* for compiler */
+	off_t target;
+	unsigned page_size = getpagesize();
+	int fd;
+	int width = 8 * sizeof(int);
+
+	/* devmem ADDRESS [WIDTH [VALUE]] */
+// TODO: options?
+// -r: read and output only the value in hex, with 0x prefix
+// -w: write only, no reads before or after, and no output
+// or make this behavior default?
+// Let's try this and see how users react.
+
+	/* ADDRESS */
+	if (!argv[1])
+		bb_show_usage();
+	errno = 0;
+	target = bb_strtoull(argv[1], NULL, 0); /* allows hex, oct etc */
+
+	/* WIDTH */
+	if (argv[2]) {
+		if (isdigit(argv[2][0]) || argv[2][1])
+			width = xatou(argv[2]);
+		else {
+			static const char bhwl[] ALIGN1 = "bhwl";
+			static const uint8_t sizes[] ALIGN1 = {
+				8 * sizeof(char),
+				8 * sizeof(short),
+				8 * sizeof(int),
+				8 * sizeof(long),
+				0 /* bad */
+			};
+			width = strchrnul(bhwl, (argv[2][0] | 0x20)) - bhwl;
+			width = sizes[width];
+		}
+		/* VALUE */
+		if (argv[3])
+			writeval = bb_strtoull(argv[3], NULL, 0);
+	} else { /* argv[2] == NULL */
+		/* make argv[3] to be a valid thing to use */
+		argv--;
+	}
+	if (errno)
+		bb_show_usage(); /* bb_strtouXX failed */
+
+	fd = xopen("/dev/mem", argv[3] ? (O_RDWR | O_SYNC) : (O_RDONLY | O_SYNC));
+	map_base = mmap(NULL,
+			page_size * 2 /* in case value spans page */,
+			argv[3] ? (PROT_READ | PROT_WRITE) : PROT_READ,
+			MAP_SHARED,
+			fd,
+			target & ~(off_t)(page_size - 1));
+	if (map_base == MAP_FAILED)
+		bb_perror_msg_and_die("mmap");
+
+//	printf("Memory mapped at address %p.\n", map_base);
+
+	virt_addr = (char*)map_base + (target & (page_size - 1));
+
+	if (!argv[3]) {
+		switch (width) {
+		case 8:
+			read_result = *(volatile uint8_t*)virt_addr;
+			break;
+		case 16:
+			read_result = *(volatile uint16_t*)virt_addr;
+			break;
+		case 32:
+			read_result = *(volatile uint32_t*)virt_addr;
+			break;
+		case 64:
+			read_result = *(volatile uint64_t*)virt_addr;
+			break;
+		default:
+			bb_error_msg_and_die("bad width");
+		}
+//		printf("Value at address 0x%"OFF_FMT"X (%p): 0x%llX\n",
+//			target, virt_addr,
+//			(unsigned long long)read_result);
+		/* Zero-padded output shows the width of access just done */
+		printf("0x%0*llX\n", (width >> 2), (unsigned long long)read_result);
+	} else {
+		switch (width) {
+		case 8:
+			*(volatile uint8_t*)virt_addr = writeval;
+//			read_result = *(volatile uint8_t*)virt_addr;
+			break;
+		case 16:
+			*(volatile uint16_t*)virt_addr = writeval;
+//			read_result = *(volatile uint16_t*)virt_addr;
+			break;
+		case 32:
+			*(volatile uint32_t*)virt_addr = writeval;
+//			read_result = *(volatile uint32_t*)virt_addr;
+			break;
+		case 64:
+			*(volatile uint64_t*)virt_addr = writeval;
+//			read_result = *(volatile uint64_t*)virt_addr;
+			break;
+		default:
+			bb_error_msg_and_die("bad width");
+		}
+//		printf("Written 0x%llX; readback 0x%llX\n",
+//				(unsigned long long)writeval,
+//				(unsigned long long)read_result);
+	}
+
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		if (munmap(map_base, page_size * 2) == -1)
+			bb_perror_msg_and_die("munmap");
+		close(fd);
+	}
+
+	return EXIT_SUCCESS;
+}