1 // SPDX-License-Identifier: GPL-2.0
3 * Simulated Serial Driver (fake serial)
5 * This driver is mostly used for bringup purposes and will go away.
6 * It has a strong dependency on the system console. All outputs
7 * are rerouted to the same facility as the one used by printk which, in our
8 * case means sys_sim.c console (goes via the simulator).
10 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
11 * Stephane Eranian <eranian@hpl.hp.com>
12 * David Mosberger-Tang <davidm@hpl.hp.com>
15 #include <linux/init.h>
16 #include <linux/errno.h>
17 #include <linux/sched.h>
18 #include <linux/sched/debug.h>
19 #include <linux/tty.h>
20 #include <linux/tty_flip.h>
21 #include <linux/major.h>
22 #include <linux/fcntl.h>
24 #include <linux/seq_file.h>
25 #include <linux/slab.h>
26 #include <linux/capability.h>
27 #include <linux/circ_buf.h>
28 #include <linux/console.h>
29 #include <linux/irq.h>
30 #include <linux/module.h>
31 #include <linux/serial.h>
32 #include <linux/sysrq.h>
33 #include <linux/uaccess.h>
35 #include <asm/hpsim.h>
37 #include "hpsim_ssc.h"
39 #undef SIMSERIAL_DEBUG /* define this to get some debug information */
41 #define KEYBOARD_INTR 3 /* must match with simulator! */
43 #define NR_PORTS 1 /* only one port for now */
52 static struct serial_state rs_table[NR_PORTS];
54 struct tty_driver *hp_simserial_driver;
56 static struct console *console;
58 static void receive_chars(struct tty_port *port)
61 static unsigned char seen_esc = 0;
63 while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
64 if (ch == 27 && seen_esc == 0) {
67 } else if (seen_esc == 1 && ch == 'O') {
70 } else if (seen_esc == 2) {
71 if (ch == 'P') /* F1 */
73 #ifdef CONFIG_MAGIC_SYSRQ
74 if (ch == 'S') { /* F4 */
76 ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR);
86 if (tty_insert_flip_char(port, ch, TTY_NORMAL) == 0)
89 tty_flip_buffer_push(port);
93 * This is the serial driver's interrupt routine for a single port
95 static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
97 struct serial_state *info = dev_id;
99 receive_chars(&info->port);
105 * -------------------------------------------------------------------
106 * Here ends the serial interrupt routines.
107 * -------------------------------------------------------------------
110 static int rs_put_char(struct tty_struct *tty, unsigned char ch)
112 struct serial_state *info = tty->driver_data;
118 local_irq_save(flags);
119 if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
120 local_irq_restore(flags);
123 info->xmit.buf[info->xmit.head] = ch;
124 info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
125 local_irq_restore(flags);
129 static void transmit_chars(struct tty_struct *tty, struct serial_state *info,
135 local_irq_save(flags);
138 char c = info->x_char;
140 console->write(console, &c, 1);
147 if (info->xmit.head == info->xmit.tail || tty->stopped) {
148 #ifdef SIMSERIAL_DEBUG
149 printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
150 info->xmit.head, info->xmit.tail, tty->stopped);
155 * We removed the loop and try to do it in to chunks. We need
156 * 2 operations maximum because it's a ring buffer.
158 * First from current to tail if possible.
159 * Then from the beginning of the buffer until necessary
162 count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
163 SERIAL_XMIT_SIZE - info->xmit.tail);
164 console->write(console, info->xmit.buf+info->xmit.tail, count);
166 info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);
169 * We have more at the beginning of the buffer
171 count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
173 console->write(console, info->xmit.buf, count);
174 info->xmit.tail += count;
177 local_irq_restore(flags);
180 static void rs_flush_chars(struct tty_struct *tty)
182 struct serial_state *info = tty->driver_data;
184 if (info->xmit.head == info->xmit.tail || tty->stopped ||
188 transmit_chars(tty, info, NULL);
191 static int rs_write(struct tty_struct * tty,
192 const unsigned char *buf, int count)
194 struct serial_state *info = tty->driver_data;
201 local_irq_save(flags);
203 c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
209 memcpy(info->xmit.buf + info->xmit.head, buf, c);
210 info->xmit.head = ((info->xmit.head + c) &
211 (SERIAL_XMIT_SIZE-1));
216 local_irq_restore(flags);
218 * Hey, we transmit directly from here in our case
220 if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) &&
222 transmit_chars(tty, info, NULL);
227 static int rs_write_room(struct tty_struct *tty)
229 struct serial_state *info = tty->driver_data;
231 return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
234 static int rs_chars_in_buffer(struct tty_struct *tty)
236 struct serial_state *info = tty->driver_data;
238 return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
241 static void rs_flush_buffer(struct tty_struct *tty)
243 struct serial_state *info = tty->driver_data;
246 local_irq_save(flags);
247 info->xmit.head = info->xmit.tail = 0;
248 local_irq_restore(flags);
254 * This function is used to send a high-priority XON/XOFF character to
257 static void rs_send_xchar(struct tty_struct *tty, char ch)
259 struct serial_state *info = tty->driver_data;
264 * I guess we could call console->write() directly but
265 * let's do that for now.
267 transmit_chars(tty, info, NULL);
272 * ------------------------------------------------------------
275 * This routine is called by the upper-layer tty layer to signal that
276 * incoming characters should be throttled.
277 * ------------------------------------------------------------
279 static void rs_throttle(struct tty_struct * tty)
282 rs_send_xchar(tty, STOP_CHAR(tty));
284 printk(KERN_INFO "simrs_throttle called\n");
287 static void rs_unthrottle(struct tty_struct * tty)
289 struct serial_state *info = tty->driver_data;
295 rs_send_xchar(tty, START_CHAR(tty));
297 printk(KERN_INFO "simrs_unthrottle called\n");
300 static int rs_setserial(struct tty_struct *tty, struct serial_struct *ss)
305 static int rs_getserial(struct tty_struct *tty, struct serial_struct *ss)
310 static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
312 if ((cmd != TIOCSERCONFIG) && (cmd != TIOCMIWAIT)) {
313 if (tty_io_error(tty))
321 case TIOCSERGETLSR: /* Get line status register */
327 #define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
330 * This routine will shutdown a serial port; interrupts are disabled, and
331 * DTR is dropped if the hangup on close termio flag is on.
333 static void shutdown(struct tty_port *port)
335 struct serial_state *info = container_of(port, struct serial_state,
339 local_irq_save(flags);
341 free_irq(info->irq, info);
343 if (info->xmit.buf) {
344 free_page((unsigned long) info->xmit.buf);
345 info->xmit.buf = NULL;
347 local_irq_restore(flags);
350 static void rs_close(struct tty_struct *tty, struct file * filp)
352 struct serial_state *info = tty->driver_data;
354 tty_port_close(&info->port, tty, filp);
357 static void rs_hangup(struct tty_struct *tty)
359 struct serial_state *info = tty->driver_data;
361 rs_flush_buffer(tty);
362 tty_port_hangup(&info->port);
365 static int activate(struct tty_port *port, struct tty_struct *tty)
367 struct serial_state *state = container_of(port, struct serial_state,
369 unsigned long flags, page;
372 page = get_zeroed_page(GFP_KERNEL);
376 local_irq_save(flags);
381 state->xmit.buf = (unsigned char *) page;
384 retval = request_irq(state->irq, rs_interrupt_single, 0,
390 state->xmit.head = state->xmit.tail = 0;
392 local_irq_restore(flags);
398 * This routine is called whenever a serial port is opened. It
399 * enables interrupts for a serial port, linking in its async structure into
400 * the IRQ chain. It also performs the serial-specific
401 * initialization for the tty structure.
403 static int rs_open(struct tty_struct *tty, struct file * filp)
405 struct serial_state *info = rs_table + tty->index;
406 struct tty_port *port = &info->port;
408 tty->driver_data = info;
409 port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
412 * figure out which console to use (should be one already)
414 console = console_drivers;
416 if ((console->flags & CON_ENABLED) && console->write) break;
417 console = console->next;
420 return tty_port_open(port, tty, filp);
424 * /proc fs routines....
427 static int rs_proc_show(struct seq_file *m, void *v)
431 seq_printf(m, "simserinfo:1.0\n");
432 for (i = 0; i < NR_PORTS; i++)
433 seq_printf(m, "%d: uart:16550 port:3F8 irq:%d\n",
438 static const struct tty_operations hp_ops = {
442 .put_char = rs_put_char,
443 .flush_chars = rs_flush_chars,
444 .write_room = rs_write_room,
445 .chars_in_buffer = rs_chars_in_buffer,
446 .flush_buffer = rs_flush_buffer,
448 .throttle = rs_throttle,
449 .unthrottle = rs_unthrottle,
450 .send_xchar = rs_send_xchar,
451 .set_serial = rs_setserial,
452 .get_serial = rs_getserial,
454 .proc_show = rs_proc_show,
457 static const struct tty_port_operations hp_port_ops = {
458 .activate = activate,
459 .shutdown = shutdown,
462 static int __init simrs_init(void)
464 struct serial_state *state;
467 if (!ia64_platform_is("hpsim"))
470 hp_simserial_driver = alloc_tty_driver(NR_PORTS);
471 if (!hp_simserial_driver)
474 printk(KERN_INFO "SimSerial driver with no serial options enabled\n");
476 /* Initialize the tty_driver structure */
478 hp_simserial_driver->driver_name = "simserial";
479 hp_simserial_driver->name = "ttyS";
480 hp_simserial_driver->major = TTY_MAJOR;
481 hp_simserial_driver->minor_start = 64;
482 hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
483 hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
484 hp_simserial_driver->init_termios = tty_std_termios;
485 hp_simserial_driver->init_termios.c_cflag =
486 B9600 | CS8 | CREAD | HUPCL | CLOCAL;
487 hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
488 tty_set_operations(hp_simserial_driver, &hp_ops);
491 tty_port_init(&state->port);
492 state->port.ops = &hp_port_ops;
493 state->port.close_delay = 0; /* XXX really 0? */
495 retval = hpsim_get_irq(KEYBOARD_INTR);
497 printk(KERN_ERR "%s: out of interrupt vectors!\n",
504 /* the port is imaginary */
505 printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);
507 tty_port_link_device(&state->port, hp_simserial_driver, 0);
508 retval = tty_register_driver(hp_simserial_driver);
510 printk(KERN_ERR "Couldn't register simserial driver\n");
516 put_tty_driver(hp_simserial_driver);
517 tty_port_destroy(&state->port);
522 __initcall(simrs_init);