I'm actually working on a fingerprint reader (FP reader) which I plug in USB. This FP reader is also plug on a stm32f4 board. If I understand correctly, the FP reader contains a really small database FP templates. To modify those templates, we plug the FP reader on USB and use a program on Windows to modify it. Since I'm working on Linux (and for curiosity), I'm trying to make a program which permit us to modify templates on Linux.
This FP reader is seen as a CD-ROM reader. I'm trying to communicate to it with the help of sg package (I'm following this document http://www.tldp.org/HOWTO/SCSI-Generic-HOWTO/). According to the documentation of the FP reader (you can find it here http://www.adh-tech.com.tw/files/GT-511C3_datasheet_V1%201_20131127.pdf) I should send a buffer (of 12 bytes) like that [55 aa 0001 00000000 0001 0101] to make the "open" command.
Here is my code to make this command (I tried to make a readable minimal example):
#include <errno.h>
#include <fcntl.h>
#include <scsi/sg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#define FP_PACKET_SZ 12
const uint8_t fp_packet_sz = FP_PACKET_SZ;
static unsigned char sense_buffer[32];
#define OPEN_CMD
static void init_snd(uint8_t buf[fp_packet_sz]) {
size_t offset = 0;
const uint16_t deviceID = 1;
const uint16_t cmd = 1;
const uint32_t parameter = 0;
buf[offset++] = 0x55;
buf[offset++] = 0xAA;
memcpy(buf + offset, &deviceID, sizeof(deviceID));
offset += sizeof(deviceID);
memcpy(buf + offset, ¶meter, sizeof(parameter));
offset += sizeof(parameter);
memcpy(buf + offset, &cmd, sizeof(cmd));
offset += sizeof(cmd);
uint16_t checksum = 0;
for (unsigned int i = 0 ; i < offset ; i++)
checksum += buf[i];
memcpy(buf + offset, &checksum, sizeof(checksum));
}
int main(int argc, char *argv[]) {
int fd = 0, res = 0;
char * filename = 0;
sg_io_hdr_t header;
uint8_t snd[fp_packet_sz];
uint8_t rcv[fp_packet_sz];
memset (snd, 0, sizeof(snd));
memset (rcv, 0, sizeof(rcv));
if (argc < 2) {
fprintf(stderr, "argument missing\n");
return EXIT_FAILURE;
}
filename = argv[1];
fd = open(filename, O_RDWR);
if (fd < 0) {
fprintf(stderr, "open %s failed\n", filename);
return EXIT_FAILURE;
}
init_snd(snd);
header.interface_id = 'S';
header.dxfer_direction = SG_DXFER_TO_FROM_DEV;
header.cmd_len = fp_packet_sz;
header.cmdp = snd;
header.mx_sb_len = sizeof (sense_buffer);
header.sbp = sense_buffer;
header.iovec_count = 0;
header.dxfer_len = fp_packet_sz;
header.dxferp = rcv;
header.timeout = 60000;
header.flags = 0;
if ((res = ioctl(fd, SG_IO, &header)) < 0) {
fprintf(stderr, "ioctl failed and return errno: %s \n", strerror(errno));
exit(EXIT_FAILURE);
}
fprintf(stdout, "receive buffer:");
for (int i = 0 ; i < fp_packet_sz ; i++)
fprintf(stdout, " %02x", rcv[i]);
fprintf(stdout, "\n");
fprintf(stdout, "sense data:");
for (int i = 0 ; i < header.sb_len_wr ; i++)
fprintf(stdout, " %02x", sense_buffer[i]);
fprintf(stdout, "\n");
return EXIT_SUCCESS;
}
What I expected was the rcv to have the following value [55 aa 00 01 00 00 00 00 00 30 01 30].
But instead, I received nothing (or something I don't understand) and the sense_data get the following value: 70 00 05 00 00 00 00 0A 00 00 00 00 20 00 00 00 00 00 which correspond to an Illegal Request (according to http://blog.disksurvey.org/knowledge-base/scsi-sense/ blog). I also tried to use the same scheme as scsi_inquiry.c as said in that forum http://www.linuxquestions.org/questions/programming-9/linux-scsi-passthrough-porting-windows-routine-4175528749/ and I get the same sense_data. I think I don't really understand how sg driver work. Is that the driver which gives the sense_data or the device ? I also try to make some read() and write() on /dev/sr1 but it didn't work (seems like I only can read some information about the format of the memory of the FP reader)
Some additional information given by sg commands in a terminal:
>sg_map
/dev/sg3 /dev/sr1
>sg_inq /dev/sg3
invalid VPD response; probably a STANDARD INQUIRY response
standard INQUIRY:
PQual=0 Device_type=5 RMB=1 LU_CONG=0 version=0x06 [SPC-4]
[AERC=0] [TrmTsk=0] NormACA=0 HiSUP=0 Resp_data_format=2
SCCS=0 ACC=0 TPGS=0 3PC=0 Protect=0 [BQue=0]
EncServ=0 MultiP=0 [MChngr=0] [ACKREQQ=0] Addr16=0
[RelAdr=0] WBus16=0 Sync=0 [Linked=0] [TranDis=0] CmdQue=0
length=36 (0x24) Peripheral device type: cd/dvd
Vendor identification:
Product identification: Fingerprint
Product revision level: 0.01
If you need any more information, tell me, I will add it to that post.
Resume of the question: How can I send a particular command (buffer) to a fingerprint reader by using scsi driver in Linux (sg) or any other program ?
Thank you for your (maybe) future help.
EDIT1: Here is the exact value of snd buffer sent to the device (given by gdb)
gdb> x /3xw snd
0x0001aa55 0x00000000 0x01010001
