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