tools: Add tool to add crc8 to a mac address

This patch adds a little tool that takes a generic MAC address and
generates a CRC byte for it. The output is the full MAC address without
any separators, ready written into an EEPROM.

Signed-off-by: Olliver Schinagl <o.schinagl@ultimaker.com>
Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

tools/.gitignore

@@ -6,6 +6,7 @@
 /fit_check_sign
 /fit_info
 /gen_eth_addr
+/gen_ethaddr_crc
 /ifdtool
 /img2srec
 /kwboot

tools/Makefile

@@ -43,6 +43,10 @@ envcrc-objs := envcrc.o lib/crc32.o common/env_embedded.o lib/sha1.o
 hostprogs-$(CONFIG_CMD_NET) += gen_eth_addr
 HOSTCFLAGS_gen_eth_addr.o := -pedantic
 
+hostprogs-$(CONFIG_CMD_NET) += gen_ethaddr_crc
+gen_ethaddr_crc-objs := gen_ethaddr_crc.o lib/crc8.o
+HOSTCFLAGS_gen_ethaddr_crc.o := -pedantic
+
 hostprogs-$(CONFIG_CMD_LOADS) += img2srec
 HOSTCFLAGS_img2srec.o := -pedantic
 

tools/gen_ethaddr_crc.c

@@ -0,0 +1,75 @@
+/*
+ * (C) Copyright 2016
+ * Olliver Schinagl <oliver@schinagl.nl>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <ctype.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <u-boot/crc.h>
+
+#define ARP_HLEN 6 /* Length of hardware address */
+#define ARP_HLEN_ASCII (ARP_HLEN * 2) + (ARP_HLEN - 1) /* with separators */
+#define ARP_HLEN_LAZY (ARP_HLEN * 2) /* separatorless hardware address length */
+
+uint8_t nibble_to_hex(const char *nibble, bool lo)
+{
+	return (strtol(nibble, NULL, 16) << (lo ? 0 : 4)) & (lo ? 0x0f : 0xf0);
+}
+
+int process_mac(const char *mac_address)
+{
+	uint8_t ethaddr[ARP_HLEN + 1] = { 0x00 };
+	uint_fast8_t i = 0;
+
+	while (*mac_address != '\0') {
+		char nibble[2] = { 0x00, '\n' }; /* for strtol */
+
+		nibble[0] = *mac_address++;
+		if (isxdigit(nibble[0])) {
+			if (isupper(nibble[0]))
+				nibble[0] = tolower(nibble[0]);
+			ethaddr[i >> 1] |= nibble_to_hex(nibble, (i % 2) != 0);
+			i++;
+		}
+	}
+
+	for (i = 0; i < ARP_HLEN; i++)
+		printf("%.2x", ethaddr[i]);
+	printf("%.2x\n", crc8(0, ethaddr, ARP_HLEN));
+
+	return 0;
+}
+
+void print_usage(char *cmdname)
+{
+	printf("Usage: %s <mac_address>\n", cmdname);
+	puts("<mac_address> may be with or without separators.");
+	puts("Valid seperators are ':' and '-'.");
+	puts("<mac_address> digits are in base 16.\n");
+}
+
+int main(int argc, char *argv[])
+{
+	if (argc < 2) {
+		print_usage(argv[0]);
+		return 1;
+	}
+
+	if (!((strlen(argv[1]) == ARP_HLEN_ASCII) || (strlen(argv[1]) == ARP_HLEN_LAZY))) {
+		puts("The MAC address is not valid.\n");
+		print_usage(argv[0]);
+		return 1;
+	}
+
+	if (process_mac(argv[1])) {
+		puts("Failed to calculate the MAC's checksum.");
+		return 1;
+	}
+
+	return 0;
+}