1*4882a593Smuzhiyun============================= 2*4882a593SmuzhiyunISO7816 Serial Communications 3*4882a593Smuzhiyun============================= 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun1. Introduction 6*4882a593Smuzhiyun=============== 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun ISO/IEC7816 is a series of standards specifying integrated circuit cards (ICC) 9*4882a593Smuzhiyun also known as smart cards. 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun2. Hardware-related considerations 12*4882a593Smuzhiyun================================== 13*4882a593Smuzhiyun 14*4882a593Smuzhiyun Some CPUs/UARTs (e.g., Microchip AT91) contain a built-in mode capable of 15*4882a593Smuzhiyun handling communication with a smart card. 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun For these microcontrollers, the Linux driver should be made capable of 18*4882a593Smuzhiyun working in both modes, and proper ioctls (see later) should be made 19*4882a593Smuzhiyun available at user-level to allow switching from one mode to the other, and 20*4882a593Smuzhiyun vice versa. 21*4882a593Smuzhiyun 22*4882a593Smuzhiyun3. Data Structures Already Available in the Kernel 23*4882a593Smuzhiyun================================================== 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun The Linux kernel provides the serial_iso7816 structure (see [1]) to handle 26*4882a593Smuzhiyun ISO7816 communications. This data structure is used to set and configure 27*4882a593Smuzhiyun ISO7816 parameters in ioctls. 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun Any driver for devices capable of working both as RS232 and ISO7816 should 30*4882a593Smuzhiyun implement the iso7816_config callback in the uart_port structure. The 31*4882a593Smuzhiyun serial_core calls iso7816_config to do the device specific part in response 32*4882a593Smuzhiyun to TIOCGISO7816 and TIOCSISO7816 ioctls (see below). The iso7816_config 33*4882a593Smuzhiyun callback receives a pointer to struct serial_iso7816. 34*4882a593Smuzhiyun 35*4882a593Smuzhiyun4. Usage from user-level 36*4882a593Smuzhiyun======================== 37*4882a593Smuzhiyun 38*4882a593Smuzhiyun From user-level, ISO7816 configuration can be get/set using the previous 39*4882a593Smuzhiyun ioctls. For instance, to set ISO7816 you can use the following code:: 40*4882a593Smuzhiyun 41*4882a593Smuzhiyun #include <linux/serial.h> 42*4882a593Smuzhiyun 43*4882a593Smuzhiyun /* Include definition for ISO7816 ioctls: TIOCSISO7816 and TIOCGISO7816 */ 44*4882a593Smuzhiyun #include <sys/ioctl.h> 45*4882a593Smuzhiyun 46*4882a593Smuzhiyun /* Open your specific device (e.g., /dev/mydevice): */ 47*4882a593Smuzhiyun int fd = open ("/dev/mydevice", O_RDWR); 48*4882a593Smuzhiyun if (fd < 0) { 49*4882a593Smuzhiyun /* Error handling. See errno. */ 50*4882a593Smuzhiyun } 51*4882a593Smuzhiyun 52*4882a593Smuzhiyun struct serial_iso7816 iso7816conf; 53*4882a593Smuzhiyun 54*4882a593Smuzhiyun /* Reserved fields as to be zeroed */ 55*4882a593Smuzhiyun memset(&iso7816conf, 0, sizeof(iso7816conf)); 56*4882a593Smuzhiyun 57*4882a593Smuzhiyun /* Enable ISO7816 mode: */ 58*4882a593Smuzhiyun iso7816conf.flags |= SER_ISO7816_ENABLED; 59*4882a593Smuzhiyun 60*4882a593Smuzhiyun /* Select the protocol: */ 61*4882a593Smuzhiyun /* T=0 */ 62*4882a593Smuzhiyun iso7816conf.flags |= SER_ISO7816_T(0); 63*4882a593Smuzhiyun /* or T=1 */ 64*4882a593Smuzhiyun iso7816conf.flags |= SER_ISO7816_T(1); 65*4882a593Smuzhiyun 66*4882a593Smuzhiyun /* Set the guard time: */ 67*4882a593Smuzhiyun iso7816conf.tg = 2; 68*4882a593Smuzhiyun 69*4882a593Smuzhiyun /* Set the clock frequency*/ 70*4882a593Smuzhiyun iso7816conf.clk = 3571200; 71*4882a593Smuzhiyun 72*4882a593Smuzhiyun /* Set transmission factors: */ 73*4882a593Smuzhiyun iso7816conf.sc_fi = 372; 74*4882a593Smuzhiyun iso7816conf.sc_di = 1; 75*4882a593Smuzhiyun 76*4882a593Smuzhiyun if (ioctl(fd_usart, TIOCSISO7816, &iso7816conf) < 0) { 77*4882a593Smuzhiyun /* Error handling. See errno. */ 78*4882a593Smuzhiyun } 79*4882a593Smuzhiyun 80*4882a593Smuzhiyun /* Use read() and write() syscalls here... */ 81*4882a593Smuzhiyun 82*4882a593Smuzhiyun /* Close the device when finished: */ 83*4882a593Smuzhiyun if (close (fd) < 0) { 84*4882a593Smuzhiyun /* Error handling. See errno. */ 85*4882a593Smuzhiyun } 86*4882a593Smuzhiyun 87*4882a593Smuzhiyun5. References 88*4882a593Smuzhiyun============= 89*4882a593Smuzhiyun 90*4882a593Smuzhiyun [1] include/uapi/linux/serial.h 91