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Diffstat (limited to 'Documentation/usb/gadget_printer.txt')
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diff --git a/Documentation/usb/gadget_printer.txt b/Documentation/usb/gadget_printer.txt new file mode 100644 index 0000000..ad995bf --- /dev/null +++ b/Documentation/usb/gadget_printer.txt @@ -0,0 +1,510 @@ + + Linux USB Printer Gadget Driver + 06/04/2007 + + Copyright (C) 2007 Craig W. Nadler <craig@nadler.us> + + + +GENERAL +======= + +This driver may be used if you are writing printer firmware using Linux as +the embedded OS. This driver has nothing to do with using a printer with +your Linux host system. + +You will need a USB device controller and a Linux driver for it that accepts +a gadget / "device class" driver using the Linux USB Gadget API. After the +USB device controller driver is loaded then load the printer gadget driver. +This will present a printer interface to the USB Host that your USB Device +port is connected to. + +This driver is structured for printer firmware that runs in user mode. The +user mode printer firmware will read and write data from the kernel mode +printer gadget driver using a device file. The printer returns a printer status +byte when the USB HOST sends a device request to get the printer status. The +user space firmware can read or write this status byte using a device file +/dev/g_printer . Both blocking and non-blocking read/write calls are supported. + + + + +HOWTO USE THIS DRIVER +===================== + +To load the USB device controller driver and the printer gadget driver. The +following example uses the Netchip 2280 USB device controller driver: + +modprobe net2280 +modprobe g_printer + + +The follow command line parameter can be used when loading the printer gadget +(ex: modprobe g_printer idVendor=0x0525 idProduct=0xa4a8 ): + +idVendor - This is the Vendor ID used in the device descriptor. The default is + the Netchip vendor id 0x0525. YOU MUST CHANGE TO YOUR OWN VENDOR ID + BEFORE RELEASING A PRODUCT. If you plan to release a product and don't + already have a Vendor ID please see www.usb.org for details on how to + get one. + +idProduct - This is the Product ID used in the device descriptor. The default + is 0xa4a8, you should change this to an ID that's not used by any of + your other USB products if you have any. It would be a good idea to + start numbering your products starting with say 0x0001. + +bcdDevice - This is the version number of your product. It would be a good idea + to put your firmware version here. + +iManufacturer - A string containing the name of the Vendor. + +iProduct - A string containing the Product Name. + +iSerialNum - A string containing the Serial Number. This should be changed for + each unit of your product. + +iPNPstring - The PNP ID string used for this printer. You will want to set + either on the command line or hard code the PNP ID string used for + your printer product. + +qlen - The number of 8k buffers to use per endpoint. The default is 10, you + should tune this for your product. You may also want to tune the + size of each buffer for your product. + + + + +USING THE EXAMPLE CODE +====================== + +This example code talks to stdout, instead of a print engine. + +To compile the test code below: + +1) save it to a file called prn_example.c +2) compile the code with the follow command: + gcc prn_example.c -o prn_example + + + +To read printer data from the host to stdout: + + # prn_example -read_data + + +To write printer data from a file (data_file) to the host: + + # cat data_file | prn_example -write_data + + +To get the current printer status for the gadget driver: + + # prn_example -get_status + + Printer status is: + Printer is NOT Selected + Paper is Out + Printer OK + + +To set printer to Selected/On-line: + + # prn_example -selected + + +To set printer to Not Selected/Off-line: + + # prn_example -not_selected + + +To set paper status to paper out: + + # prn_example -paper_out + + +To set paper status to paper loaded: + + # prn_example -paper_loaded + + +To set error status to printer OK: + + # prn_example -no_error + + +To set error status to ERROR: + + # prn_example -error + + + + +EXAMPLE CODE +============ + + +#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_printer" +#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); + } + + } + + } + + /* 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); +} |
