/* * Tiny TTY driver * * Copyright (C) 2002 Greg Kroah-Hartman (greg@kroah.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This driver shows how to create a minimal serial driver using the 2.5 * kernel's serial driver layer. It does not rely on any backing hardware, but * creates a timer that emulates data being received from some kind of * hardware. * * Compiled this driver with: CFLAGS = -Wall -O2 -fomit-frame-pointer -DMODULE -D__KERNEL__ IDIR = /path/to/linux-2.5/include/goes/here tiny_serial.o::tiny_serial.c $(CC) $(CFLAGS) -I$(IDIR) -c -o $@ $< */ #include #include #include #include #include #include #include #include #include #define DRIVER_VERSION "v1.0" #define DRIVER_AUTHOR "Greg Kroah-Hartman " #define DRIVER_DESC "Tiny serial driver" /* Module information */ MODULE_AUTHOR( DRIVER_AUTHOR ); MODULE_DESCRIPTION( DRIVER_DESC ); MODULE_LICENSE("GPL"); #define DELAY_TIME HZ * 2 /* 2 seconds per character */ #define TINY_DATA_CHARACTER 't' #define TINY_SERIAL_MAJOR 240 /* experimental range */ #define TINY_SERIAL_MINORS 1 /* only have one minor */ #define UART_NR 1 /* only use one port */ #define TINY_SERIAL_NAME "ttytiny" #define MY_NAME TINY_SERIAL_NAME #define dbg(fmt, arg...) \ do { \ if (debug) \ printk (KERN_DEBUG "%s: %s: " fmt "\n", \ MY_NAME , __FUNCTION__ , ## arg); \ } while (0) #define err(format, arg...) printk(KERN_ERR "%s: " format "\n" , MY_NAME , ## arg) #define info(format, arg...) printk(KERN_INFO "%s: " format "\n" , MY_NAME , ## arg) #define warn(format, arg...) printk(KERN_WARNING "%s: " format "\n" , MY_NAME , ## arg) static int debug; MODULE_PARM(debug, "i"); MODULE_PARM_DESC(debug, "Debugging mode enabled or not"); static struct timer_list *timer; static void tiny_stop_tx(struct uart_port *port, unsigned int tty_stop) { dbg (); } static void tiny_stop_rx(struct uart_port *port) { dbg (); } static void tiny_enable_ms(struct uart_port *port) { dbg (); } static void tiny_tx_chars(struct uart_port *port) { struct circ_buf *xmit = &port->info->xmit; int count; dbg (); if (port->x_char) { dbg ("wrote %2x", port->x_char); port->icount.tx++; port->x_char = 0; return; } if (uart_circ_empty(xmit) || uart_tx_stopped(port)) { tiny_stop_tx(port, 0); return; } count = port->fifosize >> 1; do { dbg ("wrote %2x", xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); port->icount.tx++; if (uart_circ_empty(xmit)) break; } while (--count > 0); if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_event(port, EVT_WRITE_WAKEUP); if (uart_circ_empty(xmit)) tiny_stop_tx(port, 0); } static void tiny_start_tx(struct uart_port *port, unsigned int tty_start) { dbg (); } static void tiny_timer (unsigned long data) { struct uart_port *port; struct tty_struct *tty; dbg (); port = (struct uart_port *)data; if (!port) return; if (!port->info) return; tty = port->info->tty; if (!tty) return; /* add one character to the tty port */ /* this doesn't actually push the data through unless tty->low_latency is set */ tty_insert_flip_char(tty, TINY_DATA_CHARACTER, 0); tty_flip_buffer_push(tty); /* resubmit the timer again */ timer->expires = jiffies + DELAY_TIME; add_timer (timer); /* see if we have any data to transmit */ tiny_tx_chars(port); } static unsigned int tiny_tx_empty(struct uart_port *port) { return 0; } static unsigned int tiny_get_mctrl(struct uart_port *port) { return 0; } static void tiny_set_mctrl(struct uart_port *port, unsigned int mctrl) { } static void tiny_break_ctl(struct uart_port *port, int break_state) { } static void tiny_change_speed(struct uart_port *port, unsigned int cflag, unsigned int iflag, unsigned int quot) { /* get the byte size */ switch (cflag & CSIZE) { case CS5: dbg ("data bits = 5"); break; case CS6: dbg ("data bits = 6"); break; case CS7: dbg ("data bits = 7"); break; default: // CS8 dbg ("data bits = 8"); break; } /* determine the parity */ if (cflag & PARENB) if (cflag & PARODD) dbg (" - parity = odd\n"); else dbg (" - parity = even\n"); else dbg (" - parity = none\n"); /* figure out the stop bits requested */ if (cflag & CSTOPB) dbg (" - stop bits = 2\n"); else dbg (" - stop bits = 1\n"); /* figure out the flow control settings */ if (cflag & CRTSCTS) dbg (" - RTS/CTS is enabled\n"); else dbg (" - RTS/CTS is disabled\n"); /* Set baud rate */ //UART_PUT_DIV_LO(port, (quot & 0xff)); //UART_PUT_DIV_HI(port, ((quot & 0xf00) >> 8)); } static int tiny_startup(struct uart_port *port) { /* this is the first time this port is opened */ /* do any hardware initialization needed here */ /* create our timer and submit it */ if (!timer) { timer = kmalloc (sizeof (*timer), GFP_KERNEL); if (!timer) return -ENOMEM; } timer->data = (unsigned long )port; timer->expires = jiffies + DELAY_TIME; timer->function = tiny_timer; add_timer (timer); return 0; } static void tiny_shutdown(struct uart_port *port) { /* The port is being closed by the last user. */ /* Do any hardware specific stuff here */ /* shut down our timer */ del_timer (timer); } static const char *tiny_type(struct uart_port *port) { return "tinytty"; } static void tiny_release_port(struct uart_port *port) { } static int tiny_request_port(struct uart_port *port) { return 0; } static void tiny_config_port(struct uart_port *port, int flags) { } static int tiny_verify_port(struct uart_port *port, struct serial_struct *ser) { return 0; } static struct uart_ops tiny_ops = { .tx_empty = tiny_tx_empty, .set_mctrl = tiny_set_mctrl, .get_mctrl = tiny_get_mctrl, .stop_tx = tiny_stop_tx, .start_tx = tiny_start_tx, .stop_rx = tiny_stop_rx, .enable_ms = tiny_enable_ms, .break_ctl = tiny_break_ctl, .startup = tiny_startup, .shutdown = tiny_shutdown, .change_speed = tiny_change_speed, .type = tiny_type, .release_port = tiny_release_port, .request_port = tiny_request_port, .config_port = tiny_config_port, .verify_port = tiny_verify_port, }; static struct uart_port tiny_port = { .ops = &tiny_ops, }; static struct uart_driver tiny_reg = { .owner = THIS_MODULE, .driver_name = TINY_SERIAL_NAME, .dev_name = TINY_SERIAL_NAME, .major = TINY_SERIAL_MAJOR, .minor = TINY_SERIAL_MINORS, .nr = UART_NR, }; static int __init tiny_init(void) { int result; info ("Tiny serial driver"); result = uart_register_driver(&tiny_reg); if (result) return result; result = uart_add_one_port(&tiny_reg, &tiny_port); if (result) uart_unregister_driver(&tiny_reg); return result; } module_init (tiny_init);