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@parkerlreed
Last active June 10, 2024 20:58
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Use your Steam Deck as a USB printer
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/poll.h>
#include <sys/ioctl.h>
#include <linux/usb/g_printer.h>
#define PRINTER_FILE "/dev/g_printer0"
#define BUF_SIZE 512
/*
* 'usage()' - Show program usage.
*/
static void
usage(const char *option) /* I - Option string or NULL */
{
if (option) {
fprintf(stderr,"prn_example: Unknown option \"%s\"!\n",
option);
}
fputs("\n", stderr);
fputs("Usage: prn_example -[options]\n", stderr);
fputs("Options:\n", stderr);
fputs("\n", stderr);
fputs("-get_status Get the current printer status.\n", stderr);
fputs("-selected Set the selected status to selected.\n", stderr);
fputs("-not_selected Set the selected status to NOT selected.\n",
stderr);
fputs("-error Set the error status to error.\n", stderr);
fputs("-no_error Set the error status to NO error.\n", stderr);
fputs("-paper_out Set the paper status to paper out.\n", stderr);
fputs("-paper_loaded Set the paper status to paper loaded.\n",
stderr);
fputs("-read_data Read printer data from driver.\n", stderr);
fputs("-write_data Write printer sata to driver.\n", stderr);
fputs("-NB_read_data (Non-Blocking) Read printer data from driver.\n",
stderr);
fputs("\n\n", stderr);
exit(1);
}
static int
read_printer_data()
{
struct pollfd fd[1];
/* Open device file for printer gadget. */
fd[0].fd = open(PRINTER_FILE, O_RDWR);
if (fd[0].fd < 0) {
printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
close(fd[0].fd);
return(-1);
}
fd[0].events = POLLIN | POLLRDNORM;
while (1) {
static char buf[BUF_SIZE];
int bytes_read;
int retval;
/* Wait for up to 1 second for data. */
retval = poll(fd, 1, 1000);
if (retval && (fd[0].revents & POLLRDNORM)) {
/* Read data from printer gadget driver. */
bytes_read = read(fd[0].fd, buf, BUF_SIZE);
if (bytes_read < 0) {
printf("Error %d reading from %s\n",
fd[0].fd, PRINTER_FILE);
close(fd[0].fd);
return(-1);
} else if (bytes_read > 0) {
/* Write data to standard OUTPUT (stdout). */
fwrite(buf, 1, bytes_read, stdout);
fflush(stdout);
}
} else if (bytes_read > 0) {
break;
}
}
/* Close the device file. */
close(fd[0].fd);
return 0;
}
static int
write_printer_data()
{
struct pollfd fd[1];
/* Open device file for printer gadget. */
fd[0].fd = open (PRINTER_FILE, O_RDWR);
if (fd[0].fd < 0) {
printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
close(fd[0].fd);
return(-1);
}
fd[0].events = POLLOUT | POLLWRNORM;
while (1) {
int retval;
static char buf[BUF_SIZE];
/* Read data from standard INPUT (stdin). */
int bytes_read = fread(buf, 1, BUF_SIZE, stdin);
if (!bytes_read) {
break;
}
while (bytes_read) {
/* Wait for up to 1 second to sent data. */
retval = poll(fd, 1, 1000);
/* Write data to printer gadget driver. */
if (retval && (fd[0].revents & POLLWRNORM)) {
retval = write(fd[0].fd, buf, bytes_read);
if (retval < 0) {
printf("Error %d writing to %s\n",
fd[0].fd,
PRINTER_FILE);
close(fd[0].fd);
return(-1);
} else {
bytes_read -= retval;
}
}
}
}
/* Wait until the data has been sent. */
fsync(fd[0].fd);
/* Close the device file. */
close(fd[0].fd);
return 0;
}
static int
read_NB_printer_data()
{
int fd;
static char buf[BUF_SIZE];
int bytes_read;
/* Open device file for printer gadget. */
fd = open(PRINTER_FILE, O_RDWR|O_NONBLOCK);
if (fd < 0) {
printf("Error %d opening %s\n", fd, PRINTER_FILE);
close(fd);
return(-1);
}
while (1) {
/* Read data from printer gadget driver. */
bytes_read = read(fd, buf, BUF_SIZE);
if (bytes_read <= 0) {
break;
}
/* Write data to standard OUTPUT (stdout). */
fwrite(buf, 1, bytes_read, stdout);
fflush(stdout);
}
/* Close the device file. */
close(fd);
return 0;
}
static int
get_printer_status()
{
int retval;
int fd;
/* Open device file for printer gadget. */
fd = open(PRINTER_FILE, O_RDWR);
if (fd < 0) {
printf("Error %d opening %s\n", fd, PRINTER_FILE);
close(fd);
return(-1);
}
/* Make the IOCTL call. */
retval = ioctl(fd, GADGET_GET_PRINTER_STATUS);
if (retval < 0) {
fprintf(stderr, "ERROR: Failed to set printer status\n");
return(-1);
}
/* Close the device file. */
close(fd);
return(retval);
}
static int
set_printer_status(unsigned char buf, int clear_printer_status_bit)
{
int retval;
int fd;
retval = get_printer_status();
if (retval < 0) {
fprintf(stderr, "ERROR: Failed to get printer status\n");
return(-1);
}
/* Open device file for printer gadget. */
fd = open(PRINTER_FILE, O_RDWR);
if (fd < 0) {
printf("Error %d opening %s\n", fd, PRINTER_FILE);
close(fd);
return(-1);
}
if (clear_printer_status_bit) {
retval &= ~buf;
} else {
retval |= buf;
}
/* Make the IOCTL call. */
if (ioctl(fd, GADGET_SET_PRINTER_STATUS, (unsigned char)retval)) {
fprintf(stderr, "ERROR: Failed to set printer status\n");
return(-1);
}
/* Close the device file. */
close(fd);
return 0;
}
static int
display_printer_status()
{
char printer_status;
printer_status = get_printer_status();
if (printer_status < 0) {
fprintf(stderr, "ERROR: Failed to get printer status\n");
return(-1);
}
printf("Printer status is:\n");
if (printer_status & PRINTER_SELECTED) {
printf(" Printer is Selected\n");
} else {
printf(" Printer is NOT Selected\n");
}
if (printer_status & PRINTER_PAPER_EMPTY) {
printf(" Paper is Out\n");
} else {
printf(" Paper is Loaded\n");
}
if (printer_status & PRINTER_NOT_ERROR) {
printf(" Printer OK\n");
} else {
printf(" Printer ERROR\n");
}
return(0);
}
int
main(int argc, char *argv[])
{
int i; /* Looping var */
int retval = 0;
/* No Args */
if (argc == 1) {
usage(0);
exit(0);
}
for (i = 1; i < argc && !retval; i ++) {
if (argv[i][0] != '-') {
continue;
}
if (!strcmp(argv[i], "-get_status")) {
if (display_printer_status()) {
retval = 1;
}
} else if (!strcmp(argv[i], "-paper_loaded")) {
if (set_printer_status(PRINTER_PAPER_EMPTY, 1)) {
retval = 1;
}
} else if (!strcmp(argv[i], "-paper_out")) {
if (set_printer_status(PRINTER_PAPER_EMPTY, 0)) {
retval = 1;
}
} else if (!strcmp(argv[i], "-selected")) {
if (set_printer_status(PRINTER_SELECTED, 0)) {
retval = 1;
}
} else if (!strcmp(argv[i], "-not_selected")) {
if (set_printer_status(PRINTER_SELECTED, 1)) {
retval = 1;
}
} else if (!strcmp(argv[i], "-error")) {
if (set_printer_status(PRINTER_NOT_ERROR, 1)) {
retval = 1;
}
} else if (!strcmp(argv[i], "-no_error")) {
if (set_printer_status(PRINTER_NOT_ERROR, 0)) {
retval = 1;
}
} else if (!strcmp(argv[i], "-read_data")) {
if (read_printer_data()) {
retval = 1;
}
} else if (!strcmp(argv[i], "-write_data")) {
if (write_printer_data()) {
retval = 1;
}
} else if (!strcmp(argv[i], "-NB_read_data")) {
if (read_NB_printer_data()) {
retval = 1;
}
} else {
usage(argv[i]);
retval = 1;
}
}
exit(retval);
}
@cheater
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cheater commented Feb 5, 2023

That was one issue, but ultimately the network also had to be configured differently. We've managed to figure it out, though :) Here's the result:

https://gist.github.com/cheater/00279e5b3dea743e14cf7bcd57f6c7fa

@parkerlreed
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Author

Cool!

https://hackaday.com/2023/01/31/steamdeck-become-printer/

Could you please add a license information (I think it is GPL v2) and convert it into a "normal" repository?

You can convert gists?

I linked to the source of the C (and realistically it was just one line added so it exits after the chunk of data is sent)

I'm not sure of the license of the original as it's not noted in the text file

@vazhnov
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vazhnov commented Feb 5, 2023

@parkerlreed , you can use this https://stackoverflow.com/a/37144960/5287257 to convert your gist into a normal repo.
At least there will be better "Issues" tab instead of plain comments.

@vazhnov
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vazhnov commented Feb 5, 2023

About a license — I thought everything connected with the Linux kernel is GPL v2, but I can't find proof about the documentation examples.

@cheater
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cheater commented Feb 5, 2023

It looks like the RNDIS gadget isn't going to work for sharing internet from Windows after all - looks like Windows support is dodgy:

https://gist.github.com/dafta/0aadeba3aa8bcbbc8b92a233977571ed?permalink_comment_id=4460779#gistcomment-4460779

Maybe you + dafta can figure out a way to use the ethernet gadget?

@parkerlreed
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Author

@parkerlreed , you can use this https://stackoverflow.com/a/37144960/5287257 to convert your gist into a normal repo. At least there will be better "Issues" tab instead of plain comments.

https://github.com/parkerlreed/gadget-print

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