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523 lines
11 KiB
523 lines
11 KiB
=============================== |
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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 <[email protected]> |
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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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