91 строка
2.6 KiB
ReStructuredText
91 строка
2.6 KiB
ReStructuredText
=============================
|
|
ISO7816 Serial Communications
|
|
=============================
|
|
|
|
1. Introduction
|
|
===============
|
|
|
|
ISO/IEC7816 is a series of standards specifying integrated circuit cards (ICC)
|
|
also known as smart cards.
|
|
|
|
2. Hardware-related considerations
|
|
==================================
|
|
|
|
Some CPUs/UARTs (e.g., Microchip AT91) contain a built-in mode capable of
|
|
handling communication with a smart card.
|
|
|
|
For these microcontrollers, the Linux driver should be made capable of
|
|
working in both modes, and proper ioctls (see later) should be made
|
|
available at user-level to allow switching from one mode to the other, and
|
|
vice versa.
|
|
|
|
3. Data Structures Already Available in the Kernel
|
|
==================================================
|
|
|
|
The Linux kernel provides the serial_iso7816 structure (see [1]) to handle
|
|
ISO7816 communications. This data structure is used to set and configure
|
|
ISO7816 parameters in ioctls.
|
|
|
|
Any driver for devices capable of working both as RS232 and ISO7816 should
|
|
implement the iso7816_config callback in the uart_port structure. The
|
|
serial_core calls iso7816_config to do the device specific part in response
|
|
to TIOCGISO7816 and TIOCSISO7816 ioctls (see below). The iso7816_config
|
|
callback receives a pointer to struct serial_iso7816.
|
|
|
|
4. Usage from user-level
|
|
========================
|
|
|
|
From user-level, ISO7816 configuration can be get/set using the previous
|
|
ioctls. For instance, to set ISO7816 you can use the following code::
|
|
|
|
#include <linux/serial.h>
|
|
|
|
/* Include definition for ISO7816 ioctls: TIOCSISO7816 and TIOCGISO7816 */
|
|
#include <sys/ioctl.h>
|
|
|
|
/* Open your specific device (e.g., /dev/mydevice): */
|
|
int fd = open ("/dev/mydevice", O_RDWR);
|
|
if (fd < 0) {
|
|
/* Error handling. See errno. */
|
|
}
|
|
|
|
struct serial_iso7816 iso7816conf;
|
|
|
|
/* Reserved fields as to be zeroed */
|
|
memset(&iso7816conf, 0, sizeof(iso7816conf));
|
|
|
|
/* Enable ISO7816 mode: */
|
|
iso7816conf.flags |= SER_ISO7816_ENABLED;
|
|
|
|
/* Select the protocol: */
|
|
/* T=0 */
|
|
iso7816conf.flags |= SER_ISO7816_T(0);
|
|
/* or T=1 */
|
|
iso7816conf.flags |= SER_ISO7816_T(1);
|
|
|
|
/* Set the guard time: */
|
|
iso7816conf.tg = 2;
|
|
|
|
/* Set the clock frequency*/
|
|
iso7816conf.clk = 3571200;
|
|
|
|
/* Set transmission factors: */
|
|
iso7816conf.sc_fi = 372;
|
|
iso7816conf.sc_di = 1;
|
|
|
|
if (ioctl(fd_usart, TIOCSISO7816, &iso7816conf) < 0) {
|
|
/* Error handling. See errno. */
|
|
}
|
|
|
|
/* Use read() and write() syscalls here... */
|
|
|
|
/* Close the device when finished: */
|
|
if (close (fd) < 0) {
|
|
/* Error handling. See errno. */
|
|
}
|
|
|
|
5. References
|
|
=============
|
|
|
|
[1] include/uapi/linux/serial.h
|