1*6ff4137fSMike Frysinger--------------------------------- 2*6ff4137fSMike Frysinger Ethernet Address (MAC) Handling 3*6ff4137fSMike Frysinger--------------------------------- 4*6ff4137fSMike Frysinger 5*6ff4137fSMike FrysingerThere are a variety of places in U-Boot where the MAC address is used, parsed, 6*6ff4137fSMike Frysingerand stored. This document covers proper usage of each location and the moving 7*6ff4137fSMike Frysingerof data between them. 8*6ff4137fSMike Frysinger 9*6ff4137fSMike Frysinger----------- 10*6ff4137fSMike Frysinger Locations 11*6ff4137fSMike Frysinger----------- 12*6ff4137fSMike Frysinger 13*6ff4137fSMike FrysingerHere are the places where MAC addresses might be stored: 14*6ff4137fSMike Frysinger 15*6ff4137fSMike Frysinger - board-specific location (eeprom, dedicated flash, ...) 16*6ff4137fSMike Frysinger Note: only used when mandatory due to hardware design etc... 17*6ff4137fSMike Frysinger 18*6ff4137fSMike Frysinger - environment ("ethaddr", "eth1addr", ...) (see CONFIG_ETHADDR) 19*6ff4137fSMike Frysinger Note: this is the preferred way to permanently store MAC addresses 20*6ff4137fSMike Frysinger 21*6ff4137fSMike Frysinger - ethernet data (struct eth_device -> enetaddr) 22*6ff4137fSMike Frysinger Note: these are temporary copies of the MAC address which exist only 23*6ff4137fSMike Frysinger after the respective init steps have run and only to make usage 24*6ff4137fSMike Frysinger in other places easier (to avoid constant env lookup/parsing) 25*6ff4137fSMike Frysinger 26*6ff4137fSMike Frysinger - struct bd_info and/or device tree 27*6ff4137fSMike Frysinger Note: these are temporary copies of the MAC address only for the 28*6ff4137fSMike Frysinger purpose of passing this information to an OS kernel we are about 29*6ff4137fSMike Frysinger to boot 30*6ff4137fSMike Frysinger 31*6ff4137fSMike Frysinger------- 32*6ff4137fSMike Frysinger Usage 33*6ff4137fSMike Frysinger------- 34*6ff4137fSMike Frysinger 35*6ff4137fSMike FrysingerIf the hardware design mandates that the MAC address is stored in some special 36*6ff4137fSMike Frysingerplace (like EEPROM etc...), then the board specific init code (such as the 37*6ff4137fSMike Frysingerboard-specific misc_init_r() function) is responsible for locating the MAC 38*6ff4137fSMike Frysingeraddress(es) and initializing the respective environment variable(s) from it. 39*6ff4137fSMike FrysingerNote that this shall be done if, and only if, the environment does not already 40*6ff4137fSMike Frysingercontain these environment variables, i.e. existing variable definitions must 41*6ff4137fSMike Frysingernot be overwritten. 42*6ff4137fSMike Frysinger 43*6ff4137fSMike FrysingerDuring runtime, the ethernet layer will use the environment variables to sync 44*6ff4137fSMike Frysingerthe MAC addresses to the ethernet structures. All ethernet driver code should 45*6ff4137fSMike Frysingerthen only use the enetaddr member of the eth_device structure. This is done 46*6ff4137fSMike Frysingeron every network command, so the ethernet copies will stay in sync. 47*6ff4137fSMike Frysinger 48*6ff4137fSMike FrysingerAny other code that wishes to access the MAC address should query the 49*6ff4137fSMike Frysingerenvironment directly. The helper functions documented below should make 50*6ff4137fSMike Frysingerworking with this storage much smoother. 51*6ff4137fSMike Frysinger 52*6ff4137fSMike Frysinger--------- 53*6ff4137fSMike Frysinger Helpers 54*6ff4137fSMike Frysinger--------- 55*6ff4137fSMike Frysinger 56*6ff4137fSMike FrysingerTo assist in the management of these layers, a few helper functions exist. You 57*6ff4137fSMike Frysingershould use these rather than attempt to do any kind of parsing/manipulation 58*6ff4137fSMike Frysingeryourself as many common errors have arisen in the past. 59*6ff4137fSMike Frysinger 60*6ff4137fSMike Frysinger * void eth_parse_enetaddr(const char *addr, uchar *enetaddr); 61*6ff4137fSMike Frysinger 62*6ff4137fSMike FrysingerConvert a string representation of a MAC address to the binary version. 63*6ff4137fSMike Frysingerchar *addr = "00:11:22:33:44:55"; 64*6ff4137fSMike Frysingeruchar enetaddr[6]; 65*6ff4137fSMike Frysingereth_parse_enetaddr(addr, enetaddr); 66*6ff4137fSMike Frysinger/* enetaddr now equals { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 } */ 67*6ff4137fSMike Frysinger 68*6ff4137fSMike Frysinger * int eth_getenv_enetaddr(char *name, uchar *enetaddr); 69*6ff4137fSMike Frysinger 70*6ff4137fSMike FrysingerLook up an environment variable and convert the stored address. If the address 71*6ff4137fSMike Frysingeris valid, then the function returns 1. Otherwise, the function returns 0. In 72*6ff4137fSMike Frysingerall cases, the enetaddr memory is initialized. If the env var is not found, 73*6ff4137fSMike Frysingerthen it is set to all zeros. The common function is_valid_ether_addr() is used 74*6ff4137fSMike Frysingerto determine address validity. 75*6ff4137fSMike Frysingeruchar enetaddr[6]; 76*6ff4137fSMike Frysingerif (!eth_getenv_enetaddr("ethaddr", enetaddr)) { 77*6ff4137fSMike Frysinger /* "ethaddr" is not set in the environment */ 78*6ff4137fSMike Frysinger ... try and setup "ethaddr" in the env ... 79*6ff4137fSMike Frysinger} 80*6ff4137fSMike Frysinger/* enetaddr is now set to the value stored in the ethaddr env var */ 81*6ff4137fSMike Frysinger 82*6ff4137fSMike Frysinger * int eth_setenv_enetaddr(char *name, const uchar *enetaddr); 83*6ff4137fSMike Frysinger 84*6ff4137fSMike FrysingerStore the MAC address into the named environment variable. The return value is 85*6ff4137fSMike Frysingerthe same as the setenv() function. 86*6ff4137fSMike Frysingeruchar enetaddr[6] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 }; 87*6ff4137fSMike Frysingereth_setenv_enetaddr("ethaddr", enetaddr); 88*6ff4137fSMike Frysinger/* the "ethaddr" env var should now be set to "00:11:22:33:44:55" */ 89*6ff4137fSMike Frysinger 90*6ff4137fSMike Frysinger * the %pM format modifier 91*6ff4137fSMike Frysinger 92*6ff4137fSMike FrysingerThe %pM format modifier can be used with any standard printf function to format 93*6ff4137fSMike Frysingerthe binary 6 byte array representation of a MAC address. 94*6ff4137fSMike Frysingeruchar enetaddr[6] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 }; 95*6ff4137fSMike Frysingerprintf("The MAC is %pM\n", enetaddr); 96*6ff4137fSMike Frysinger 97*6ff4137fSMike Frysingerchar buf[20]; 98*6ff4137fSMike Frysingersprintf(buf, "%pM", enetaddr); 99*6ff4137fSMike Frysinger/* the buf variable is now set to "00:11:22:33:44:55" */ 100