524 lines
11 KiB
ReStructuredText
524 lines
11 KiB
ReStructuredText
===============================
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Linux USB Printer Gadget Driver
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===============================
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06/04/2007
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Copyright (C) 2007 Craig W. Nadler <craig@nadler.us>
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General
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=======
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This driver may be used if you are writing printer firmware using Linux as
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the embedded OS. This driver has nothing to do with using a printer with
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your Linux host system.
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You will need a USB device controller and a Linux driver for it that accepts
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a gadget / "device class" driver using the Linux USB Gadget API. After the
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USB device controller driver is loaded then load the printer gadget driver.
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This will present a printer interface to the USB Host that your USB Device
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port is connected to.
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This driver is structured for printer firmware that runs in user mode. The
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user mode printer firmware will read and write data from the kernel mode
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printer gadget driver using a device file. The printer returns a printer status
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byte when the USB HOST sends a device request to get the printer status. The
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user space firmware can read or write this status byte using a device file
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/dev/g_printer . Both blocking and non-blocking read/write calls are supported.
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Howto Use This Driver
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=====================
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To load the USB device controller driver and the printer gadget driver. The
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following example uses the Netchip 2280 USB device controller driver::
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modprobe net2280
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modprobe g_printer
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The follow command line parameter can be used when loading the printer gadget
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(ex: modprobe g_printer idVendor=0x0525 idProduct=0xa4a8 ):
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idVendor
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This is the Vendor ID used in the device descriptor. The default is
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the Netchip vendor id 0x0525. YOU MUST CHANGE TO YOUR OWN VENDOR ID
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BEFORE RELEASING A PRODUCT. If you plan to release a product and don't
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already have a Vendor ID please see www.usb.org for details on how to
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get one.
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idProduct
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This is the Product ID used in the device descriptor. The default
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is 0xa4a8, you should change this to an ID that's not used by any of
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your other USB products if you have any. It would be a good idea to
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start numbering your products starting with say 0x0001.
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bcdDevice
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This is the version number of your product. It would be a good idea
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to put your firmware version here.
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iManufacturer
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A string containing the name of the Vendor.
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iProduct
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A string containing the Product Name.
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iSerialNum
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A string containing the Serial Number. This should be changed for
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each unit of your product.
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iPNPstring
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The PNP ID string used for this printer. You will want to set
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either on the command line or hard code the PNP ID string used for
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your printer product.
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qlen
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The number of 8k buffers to use per endpoint. The default is 10, you
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should tune this for your product. You may also want to tune the
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size of each buffer for your product.
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Using The Example Code
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======================
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This example code talks to stdout, instead of a print engine.
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To compile the test code below:
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1) save it to a file called prn_example.c
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2) compile the code with the follow command::
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gcc prn_example.c -o prn_example
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To read printer data from the host to stdout::
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# prn_example -read_data
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To write printer data from a file (data_file) to the host::
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# cat data_file | prn_example -write_data
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To get the current printer status for the gadget driver:::
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# prn_example -get_status
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Printer status is:
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Printer is NOT Selected
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Paper is Out
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Printer OK
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To set printer to Selected/On-line::
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# prn_example -selected
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To set printer to Not Selected/Off-line::
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# prn_example -not_selected
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To set paper status to paper out::
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# prn_example -paper_out
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To set paper status to paper loaded::
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# prn_example -paper_loaded
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To set error status to printer OK::
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# prn_example -no_error
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To set error status to ERROR::
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# prn_example -error
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Example Code
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============
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::
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <linux/poll.h>
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#include <sys/ioctl.h>
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#include <linux/usb/g_printer.h>
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#define PRINTER_FILE "/dev/g_printer"
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#define BUF_SIZE 512
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/*
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* 'usage()' - Show program usage.
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*/
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static void
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usage(const char *option) /* I - Option string or NULL */
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{
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if (option) {
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fprintf(stderr,"prn_example: Unknown option \"%s\"!\n",
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option);
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}
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fputs("\n", stderr);
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fputs("Usage: prn_example -[options]\n", stderr);
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fputs("Options:\n", stderr);
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fputs("\n", stderr);
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fputs("-get_status Get the current printer status.\n", stderr);
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fputs("-selected Set the selected status to selected.\n", stderr);
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fputs("-not_selected Set the selected status to NOT selected.\n",
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stderr);
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fputs("-error Set the error status to error.\n", stderr);
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fputs("-no_error Set the error status to NO error.\n", stderr);
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fputs("-paper_out Set the paper status to paper out.\n", stderr);
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fputs("-paper_loaded Set the paper status to paper loaded.\n",
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stderr);
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fputs("-read_data Read printer data from driver.\n", stderr);
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fputs("-write_data Write printer sata to driver.\n", stderr);
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fputs("-NB_read_data (Non-Blocking) Read printer data from driver.\n",
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stderr);
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fputs("\n\n", stderr);
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exit(1);
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}
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static int
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read_printer_data()
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{
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struct pollfd fd[1];
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/* Open device file for printer gadget. */
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fd[0].fd = open(PRINTER_FILE, O_RDWR);
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if (fd[0].fd < 0) {
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printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
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close(fd[0].fd);
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return(-1);
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}
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fd[0].events = POLLIN | POLLRDNORM;
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while (1) {
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static char buf[BUF_SIZE];
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int bytes_read;
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int retval;
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/* Wait for up to 1 second for data. */
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retval = poll(fd, 1, 1000);
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if (retval && (fd[0].revents & POLLRDNORM)) {
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/* Read data from printer gadget driver. */
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bytes_read = read(fd[0].fd, buf, BUF_SIZE);
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if (bytes_read < 0) {
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printf("Error %d reading from %s\n",
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fd[0].fd, PRINTER_FILE);
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close(fd[0].fd);
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return(-1);
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} else if (bytes_read > 0) {
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/* Write data to standard OUTPUT (stdout). */
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fwrite(buf, 1, bytes_read, stdout);
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fflush(stdout);
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}
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}
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}
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/* Close the device file. */
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close(fd[0].fd);
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return 0;
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}
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static int
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write_printer_data()
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{
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struct pollfd fd[1];
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/* Open device file for printer gadget. */
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fd[0].fd = open (PRINTER_FILE, O_RDWR);
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if (fd[0].fd < 0) {
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printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
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close(fd[0].fd);
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return(-1);
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}
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fd[0].events = POLLOUT | POLLWRNORM;
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while (1) {
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int retval;
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static char buf[BUF_SIZE];
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/* Read data from standard INPUT (stdin). */
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int bytes_read = fread(buf, 1, BUF_SIZE, stdin);
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if (!bytes_read) {
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break;
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}
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while (bytes_read) {
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/* Wait for up to 1 second to sent data. */
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retval = poll(fd, 1, 1000);
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/* Write data to printer gadget driver. */
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if (retval && (fd[0].revents & POLLWRNORM)) {
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retval = write(fd[0].fd, buf, bytes_read);
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if (retval < 0) {
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printf("Error %d writing to %s\n",
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fd[0].fd,
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PRINTER_FILE);
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close(fd[0].fd);
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return(-1);
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} else {
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bytes_read -= retval;
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}
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}
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}
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}
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/* Wait until the data has been sent. */
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fsync(fd[0].fd);
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/* Close the device file. */
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close(fd[0].fd);
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return 0;
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}
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static int
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read_NB_printer_data()
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{
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int fd;
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static char buf[BUF_SIZE];
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int bytes_read;
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/* Open device file for printer gadget. */
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fd = open(PRINTER_FILE, O_RDWR|O_NONBLOCK);
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if (fd < 0) {
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printf("Error %d opening %s\n", fd, PRINTER_FILE);
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close(fd);
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return(-1);
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}
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while (1) {
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/* Read data from printer gadget driver. */
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bytes_read = read(fd, buf, BUF_SIZE);
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if (bytes_read <= 0) {
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break;
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}
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/* Write data to standard OUTPUT (stdout). */
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fwrite(buf, 1, bytes_read, stdout);
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fflush(stdout);
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}
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/* Close the device file. */
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close(fd);
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return 0;
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}
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static int
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get_printer_status()
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{
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int retval;
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int fd;
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/* Open device file for printer gadget. */
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fd = open(PRINTER_FILE, O_RDWR);
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if (fd < 0) {
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printf("Error %d opening %s\n", fd, PRINTER_FILE);
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close(fd);
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return(-1);
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}
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/* Make the IOCTL call. */
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retval = ioctl(fd, GADGET_GET_PRINTER_STATUS);
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if (retval < 0) {
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fprintf(stderr, "ERROR: Failed to set printer status\n");
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return(-1);
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}
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/* Close the device file. */
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close(fd);
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return(retval);
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}
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static int
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set_printer_status(unsigned char buf, int clear_printer_status_bit)
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{
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int retval;
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int fd;
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retval = get_printer_status();
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if (retval < 0) {
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fprintf(stderr, "ERROR: Failed to get printer status\n");
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return(-1);
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}
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/* Open device file for printer gadget. */
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fd = open(PRINTER_FILE, O_RDWR);
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if (fd < 0) {
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printf("Error %d opening %s\n", fd, PRINTER_FILE);
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close(fd);
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return(-1);
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}
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if (clear_printer_status_bit) {
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retval &= ~buf;
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} else {
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retval |= buf;
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}
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/* Make the IOCTL call. */
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if (ioctl(fd, GADGET_SET_PRINTER_STATUS, (unsigned char)retval)) {
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fprintf(stderr, "ERROR: Failed to set printer status\n");
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return(-1);
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}
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/* Close the device file. */
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close(fd);
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return 0;
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}
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static int
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display_printer_status()
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{
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char printer_status;
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printer_status = get_printer_status();
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if (printer_status < 0) {
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fprintf(stderr, "ERROR: Failed to get printer status\n");
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return(-1);
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}
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printf("Printer status is:\n");
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if (printer_status & PRINTER_SELECTED) {
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printf(" Printer is Selected\n");
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} else {
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printf(" Printer is NOT Selected\n");
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}
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if (printer_status & PRINTER_PAPER_EMPTY) {
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printf(" Paper is Out\n");
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} else {
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printf(" Paper is Loaded\n");
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}
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if (printer_status & PRINTER_NOT_ERROR) {
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printf(" Printer OK\n");
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} else {
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printf(" Printer ERROR\n");
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}
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return(0);
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}
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int
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main(int argc, char *argv[])
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{
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int i; /* Looping var */
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int retval = 0;
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/* No Args */
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if (argc == 1) {
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usage(0);
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exit(0);
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}
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for (i = 1; i < argc && !retval; i ++) {
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if (argv[i][0] != '-') {
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continue;
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}
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if (!strcmp(argv[i], "-get_status")) {
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if (display_printer_status()) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-paper_loaded")) {
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if (set_printer_status(PRINTER_PAPER_EMPTY, 1)) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-paper_out")) {
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if (set_printer_status(PRINTER_PAPER_EMPTY, 0)) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-selected")) {
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if (set_printer_status(PRINTER_SELECTED, 0)) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-not_selected")) {
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if (set_printer_status(PRINTER_SELECTED, 1)) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-error")) {
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if (set_printer_status(PRINTER_NOT_ERROR, 1)) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-no_error")) {
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if (set_printer_status(PRINTER_NOT_ERROR, 0)) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-read_data")) {
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if (read_printer_data()) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-write_data")) {
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if (write_printer_data()) {
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retval = 1;
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}
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} else if (!strcmp(argv[i], "-NB_read_data")) {
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if (read_NB_printer_data()) {
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retval = 1;
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}
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} else {
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usage(argv[i]);
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retval = 1;
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}
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}
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exit(retval);
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}
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