1 ============================= 1 =============================
2 ISO7816 Serial Communications 2 ISO7816 Serial Communications
3 ============================= 3 =============================
4 4
5 1. Introduction 5 1. Introduction
6 =============== 6 ===============
7 7
8 ISO/IEC7816 is a series of standards specify 8 ISO/IEC7816 is a series of standards specifying integrated circuit cards (ICC)
9 also known as smart cards. 9 also known as smart cards.
10 10
11 2. Hardware-related considerations 11 2. Hardware-related considerations
12 ================================== 12 ==================================
13 13
14 Some CPUs/UARTs (e.g., Microchip AT91) conta 14 Some CPUs/UARTs (e.g., Microchip AT91) contain a built-in mode capable of
15 handling communication with a smart card. 15 handling communication with a smart card.
16 16
17 For these microcontrollers, the Linux driver 17 For these microcontrollers, the Linux driver should be made capable of
18 working in both modes, and proper ioctls (se 18 working in both modes, and proper ioctls (see later) should be made
19 available at user-level to allow switching f 19 available at user-level to allow switching from one mode to the other, and
20 vice versa. 20 vice versa.
21 21
22 3. Data Structures Already Available in the Ke 22 3. Data Structures Already Available in the Kernel
23 ============================================== 23 ==================================================
24 24
25 The Linux kernel provides the serial_iso7816 25 The Linux kernel provides the serial_iso7816 structure (see [1]) to handle
26 ISO7816 communications. This data structure 26 ISO7816 communications. This data structure is used to set and configure
27 ISO7816 parameters in ioctls. 27 ISO7816 parameters in ioctls.
28 28
29 Any driver for devices capable of working bo 29 Any driver for devices capable of working both as RS232 and ISO7816 should
30 implement the iso7816_config callback in the 30 implement the iso7816_config callback in the uart_port structure. The
31 serial_core calls iso7816_config to do the d 31 serial_core calls iso7816_config to do the device specific part in response
32 to TIOCGISO7816 and TIOCSISO7816 ioctls (see 32 to TIOCGISO7816 and TIOCSISO7816 ioctls (see below). The iso7816_config
33 callback receives a pointer to struct serial 33 callback receives a pointer to struct serial_iso7816.
34 34
35 4. Usage from user-level 35 4. Usage from user-level
36 ======================== 36 ========================
37 37
38 From user-level, ISO7816 configuration can b 38 From user-level, ISO7816 configuration can be get/set using the previous
39 ioctls. For instance, to set ISO7816 you can 39 ioctls. For instance, to set ISO7816 you can use the following code::
40 40
41 #include <linux/serial.h> 41 #include <linux/serial.h>
42 42
43 /* Include definition for ISO7816 ioct 43 /* Include definition for ISO7816 ioctls: TIOCSISO7816 and TIOCGISO7816 */
44 #include <sys/ioctl.h> 44 #include <sys/ioctl.h>
45 45
46 /* Open your specific device (e.g., /d 46 /* Open your specific device (e.g., /dev/mydevice): */
47 int fd = open ("/dev/mydevice", O_RDWR 47 int fd = open ("/dev/mydevice", O_RDWR);
48 if (fd < 0) { 48 if (fd < 0) {
49 /* Error handling. See errno. 49 /* Error handling. See errno. */
50 } 50 }
51 51
52 struct serial_iso7816 iso7816conf; 52 struct serial_iso7816 iso7816conf;
53 53
54 /* Reserved fields as to be zeroed */ 54 /* Reserved fields as to be zeroed */
55 memset(&iso7816conf, 0, sizeof(iso7816 55 memset(&iso7816conf, 0, sizeof(iso7816conf));
56 56
57 /* Enable ISO7816 mode: */ 57 /* Enable ISO7816 mode: */
58 iso7816conf.flags |= SER_ISO7816_ENABL 58 iso7816conf.flags |= SER_ISO7816_ENABLED;
59 59
60 /* Select the protocol: */ 60 /* Select the protocol: */
61 /* T=0 */ 61 /* T=0 */
62 iso7816conf.flags |= SER_ISO7816_T(0); 62 iso7816conf.flags |= SER_ISO7816_T(0);
63 /* or T=1 */ 63 /* or T=1 */
64 iso7816conf.flags |= SER_ISO7816_T(1); 64 iso7816conf.flags |= SER_ISO7816_T(1);
65 65
66 /* Set the guard time: */ 66 /* Set the guard time: */
67 iso7816conf.tg = 2; 67 iso7816conf.tg = 2;
68 68
69 /* Set the clock frequency*/ 69 /* Set the clock frequency*/
70 iso7816conf.clk = 3571200; 70 iso7816conf.clk = 3571200;
71 71
72 /* Set transmission factors: */ 72 /* Set transmission factors: */
73 iso7816conf.sc_fi = 372; 73 iso7816conf.sc_fi = 372;
74 iso7816conf.sc_di = 1; 74 iso7816conf.sc_di = 1;
75 75
76 if (ioctl(fd_usart, TIOCSISO7816, &iso 76 if (ioctl(fd_usart, TIOCSISO7816, &iso7816conf) < 0) {
77 /* Error handling. See errno. 77 /* Error handling. See errno. */
78 } 78 }
79 79
80 /* Use read() and write() syscalls her 80 /* Use read() and write() syscalls here... */
81 81
82 /* Close the device when finished: */ 82 /* Close the device when finished: */
83 if (close (fd) < 0) { 83 if (close (fd) < 0) {
84 /* Error handling. See errno. 84 /* Error handling. See errno. */
85 } 85 }
86 86
87 5. References 87 5. References
88 ============= 88 =============
89 89
90 [1] include/uapi/linux/serial.h 90 [1] include/uapi/linux/serial.h
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