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