1/*
2 * Simulated Serial Driver (fake serial)
3 *
4 * This driver is mostly used for bringup purposes and will go away.
5 * It has a strong dependency on the system console. All outputs
6 * are rerouted to the same facility as the one used by printk which, in our
7 * case means sys_sim.c console (goes via the simulator).
8 *
9 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
10 *	Stephane Eranian <eranian@hpl.hp.com>
11 *	David Mosberger-Tang <davidm@hpl.hp.com>
12 */
13
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/sched.h>
17#include <linux/tty.h>
18#include <linux/tty_flip.h>
19#include <linux/major.h>
20#include <linux/fcntl.h>
21#include <linux/mm.h>
22#include <linux/seq_file.h>
23#include <linux/slab.h>
24#include <linux/capability.h>
25#include <linux/circ_buf.h>
26#include <linux/console.h>
27#include <linux/irq.h>
28#include <linux/module.h>
29#include <linux/serial.h>
30#include <linux/sysrq.h>
31#include <linux/uaccess.h>
32
33#include <asm/hpsim.h>
34
35#include "hpsim_ssc.h"
36
37#undef SIMSERIAL_DEBUG	/* define this to get some debug information */
38
39#define KEYBOARD_INTR	3	/* must match with simulator! */
40
41#define NR_PORTS	1	/* only one port for now */
42
43struct serial_state {
44	struct tty_port port;
45	struct circ_buf xmit;
46	int irq;
47	int x_char;
48};
49
50static struct serial_state rs_table[NR_PORTS];
51
52struct tty_driver *hp_simserial_driver;
53
54static struct console *console;
55
56static void receive_chars(struct tty_port *port)
57{
58	unsigned char ch;
59	static unsigned char seen_esc = 0;
60
61	while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
62		if (ch == 27 && seen_esc == 0) {
63			seen_esc = 1;
64			continue;
65		} else if (seen_esc == 1 && ch == 'O') {
66			seen_esc = 2;
67			continue;
68		} else if (seen_esc == 2) {
69			if (ch == 'P') /* F1 */
70				show_state();
71#ifdef CONFIG_MAGIC_SYSRQ
72			if (ch == 'S') { /* F4 */
73				do {
74					ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR);
75				} while (!ch);
76				handle_sysrq(ch);
77			}
78#endif
79			seen_esc = 0;
80			continue;
81		}
82		seen_esc = 0;
83
84		if (tty_insert_flip_char(port, ch, TTY_NORMAL) == 0)
85			break;
86	}
87	tty_flip_buffer_push(port);
88}
89
90/*
91 * This is the serial driver's interrupt routine for a single port
92 */
93static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
94{
95	struct serial_state *info = dev_id;
96
97	receive_chars(&info->port);
98
99	return IRQ_HANDLED;
100}
101
102/*
103 * -------------------------------------------------------------------
104 * Here ends the serial interrupt routines.
105 * -------------------------------------------------------------------
106 */
107
108static int rs_put_char(struct tty_struct *tty, unsigned char ch)
109{
110	struct serial_state *info = tty->driver_data;
111	unsigned long flags;
112
113	if (!info->xmit.buf)
114		return 0;
115
116	local_irq_save(flags);
117	if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
118		local_irq_restore(flags);
119		return 0;
120	}
121	info->xmit.buf[info->xmit.head] = ch;
122	info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
123	local_irq_restore(flags);
124	return 1;
125}
126
127static void transmit_chars(struct tty_struct *tty, struct serial_state *info,
128		int *intr_done)
129{
130	int count;
131	unsigned long flags;
132
133	local_irq_save(flags);
134
135	if (info->x_char) {
136		char c = info->x_char;
137
138		console->write(console, &c, 1);
139
140		info->x_char = 0;
141
142		goto out;
143	}
144
145	if (info->xmit.head == info->xmit.tail || tty->stopped) {
146#ifdef SIMSERIAL_DEBUG
147		printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
148		       info->xmit.head, info->xmit.tail, tty->stopped);
149#endif
150		goto out;
151	}
152	/*
153	 * We removed the loop and try to do it in to chunks. We need
154	 * 2 operations maximum because it's a ring buffer.
155	 *
156	 * First from current to tail if possible.
157	 * Then from the beginning of the buffer until necessary
158	 */
159
160	count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
161		    SERIAL_XMIT_SIZE - info->xmit.tail);
162	console->write(console, info->xmit.buf+info->xmit.tail, count);
163
164	info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);
165
166	/*
167	 * We have more at the beginning of the buffer
168	 */
169	count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
170	if (count) {
171		console->write(console, info->xmit.buf, count);
172		info->xmit.tail += count;
173	}
174out:
175	local_irq_restore(flags);
176}
177
178static void rs_flush_chars(struct tty_struct *tty)
179{
180	struct serial_state *info = tty->driver_data;
181
182	if (info->xmit.head == info->xmit.tail || tty->stopped ||
183			!info->xmit.buf)
184		return;
185
186	transmit_chars(tty, info, NULL);
187}
188
189static int rs_write(struct tty_struct * tty,
190		    const unsigned char *buf, int count)
191{
192	struct serial_state *info = tty->driver_data;
193	int	c, ret = 0;
194	unsigned long flags;
195
196	if (!info->xmit.buf)
197		return 0;
198
199	local_irq_save(flags);
200	while (1) {
201		c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
202		if (count < c)
203			c = count;
204		if (c <= 0) {
205			break;
206		}
207		memcpy(info->xmit.buf + info->xmit.head, buf, c);
208		info->xmit.head = ((info->xmit.head + c) &
209				   (SERIAL_XMIT_SIZE-1));
210		buf += c;
211		count -= c;
212		ret += c;
213	}
214	local_irq_restore(flags);
215	/*
216	 * Hey, we transmit directly from here in our case
217	 */
218	if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) &&
219			!tty->stopped)
220		transmit_chars(tty, info, NULL);
221
222	return ret;
223}
224
225static int rs_write_room(struct tty_struct *tty)
226{
227	struct serial_state *info = tty->driver_data;
228
229	return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
230}
231
232static int rs_chars_in_buffer(struct tty_struct *tty)
233{
234	struct serial_state *info = tty->driver_data;
235
236	return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
237}
238
239static void rs_flush_buffer(struct tty_struct *tty)
240{
241	struct serial_state *info = tty->driver_data;
242	unsigned long flags;
243
244	local_irq_save(flags);
245	info->xmit.head = info->xmit.tail = 0;
246	local_irq_restore(flags);
247
248	tty_wakeup(tty);
249}
250
251/*
252 * This function is used to send a high-priority XON/XOFF character to
253 * the device
254 */
255static void rs_send_xchar(struct tty_struct *tty, char ch)
256{
257	struct serial_state *info = tty->driver_data;
258
259	info->x_char = ch;
260	if (ch) {
261		/*
262		 * I guess we could call console->write() directly but
263		 * let's do that for now.
264		 */
265		transmit_chars(tty, info, NULL);
266	}
267}
268
269/*
270 * ------------------------------------------------------------
271 * rs_throttle()
272 *
273 * This routine is called by the upper-layer tty layer to signal that
274 * incoming characters should be throttled.
275 * ------------------------------------------------------------
276 */
277static void rs_throttle(struct tty_struct * tty)
278{
279	if (I_IXOFF(tty))
280		rs_send_xchar(tty, STOP_CHAR(tty));
281
282	printk(KERN_INFO "simrs_throttle called\n");
283}
284
285static void rs_unthrottle(struct tty_struct * tty)
286{
287	struct serial_state *info = tty->driver_data;
288
289	if (I_IXOFF(tty)) {
290		if (info->x_char)
291			info->x_char = 0;
292		else
293			rs_send_xchar(tty, START_CHAR(tty));
294	}
295	printk(KERN_INFO "simrs_unthrottle called\n");
296}
297
298static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
299{
300	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
301	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
302	    (cmd != TIOCMIWAIT)) {
303		if (tty->flags & (1 << TTY_IO_ERROR))
304		    return -EIO;
305	}
306
307	switch (cmd) {
308	case TIOCGSERIAL:
309	case TIOCSSERIAL:
310	case TIOCSERGSTRUCT:
311	case TIOCMIWAIT:
312		return 0;
313	case TIOCSERCONFIG:
314	case TIOCSERGETLSR: /* Get line status register */
315		return -EINVAL;
316	case TIOCSERGWILD:
317	case TIOCSERSWILD:
318		/* "setserial -W" is called in Debian boot */
319		printk (KERN_INFO "TIOCSER?WILD ioctl obsolete, ignored.\n");
320		return 0;
321	}
322	return -ENOIOCTLCMD;
323}
324
325#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
326
327/*
328 * This routine will shutdown a serial port; interrupts are disabled, and
329 * DTR is dropped if the hangup on close termio flag is on.
330 */
331static void shutdown(struct tty_port *port)
332{
333	struct serial_state *info = container_of(port, struct serial_state,
334			port);
335	unsigned long flags;
336
337	local_irq_save(flags);
338	if (info->irq)
339		free_irq(info->irq, info);
340
341	if (info->xmit.buf) {
342		free_page((unsigned long) info->xmit.buf);
343		info->xmit.buf = NULL;
344	}
345	local_irq_restore(flags);
346}
347
348static void rs_close(struct tty_struct *tty, struct file * filp)
349{
350	struct serial_state *info = tty->driver_data;
351
352	tty_port_close(&info->port, tty, filp);
353}
354
355static void rs_hangup(struct tty_struct *tty)
356{
357	struct serial_state *info = tty->driver_data;
358
359	rs_flush_buffer(tty);
360	tty_port_hangup(&info->port);
361}
362
363static int activate(struct tty_port *port, struct tty_struct *tty)
364{
365	struct serial_state *state = container_of(port, struct serial_state,
366			port);
367	unsigned long flags, page;
368	int retval = 0;
369
370	page = get_zeroed_page(GFP_KERNEL);
371	if (!page)
372		return -ENOMEM;
373
374	local_irq_save(flags);
375
376	if (state->xmit.buf)
377		free_page(page);
378	else
379		state->xmit.buf = (unsigned char *) page;
380
381	if (state->irq) {
382		retval = request_irq(state->irq, rs_interrupt_single, 0,
383				"simserial", state);
384		if (retval)
385			goto errout;
386	}
387
388	state->xmit.head = state->xmit.tail = 0;
389
390	/*
391	 * Set up the tty->alt_speed kludge
392	 */
393	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
394		tty->alt_speed = 57600;
395	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
396		tty->alt_speed = 115200;
397	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
398		tty->alt_speed = 230400;
399	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
400		tty->alt_speed = 460800;
401
402errout:
403	local_irq_restore(flags);
404	return retval;
405}
406
407
408/*
409 * This routine is called whenever a serial port is opened.  It
410 * enables interrupts for a serial port, linking in its async structure into
411 * the IRQ chain.   It also performs the serial-specific
412 * initialization for the tty structure.
413 */
414static int rs_open(struct tty_struct *tty, struct file * filp)
415{
416	struct serial_state *info = rs_table + tty->index;
417	struct tty_port *port = &info->port;
418
419	tty->driver_data = info;
420	port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
421
422	/*
423	 * figure out which console to use (should be one already)
424	 */
425	console = console_drivers;
426	while (console) {
427		if ((console->flags & CON_ENABLED) && console->write) break;
428		console = console->next;
429	}
430
431	return tty_port_open(port, tty, filp);
432}
433
434/*
435 * /proc fs routines....
436 */
437
438static int rs_proc_show(struct seq_file *m, void *v)
439{
440	int i;
441
442	seq_printf(m, "simserinfo:1.0\n");
443	for (i = 0; i < NR_PORTS; i++)
444		seq_printf(m, "%d: uart:16550 port:3F8 irq:%d\n",
445		       i, rs_table[i].irq);
446	return 0;
447}
448
449static int rs_proc_open(struct inode *inode, struct file *file)
450{
451	return single_open(file, rs_proc_show, NULL);
452}
453
454static const struct file_operations rs_proc_fops = {
455	.owner		= THIS_MODULE,
456	.open		= rs_proc_open,
457	.read		= seq_read,
458	.llseek		= seq_lseek,
459	.release	= single_release,
460};
461
462static const struct tty_operations hp_ops = {
463	.open = rs_open,
464	.close = rs_close,
465	.write = rs_write,
466	.put_char = rs_put_char,
467	.flush_chars = rs_flush_chars,
468	.write_room = rs_write_room,
469	.chars_in_buffer = rs_chars_in_buffer,
470	.flush_buffer = rs_flush_buffer,
471	.ioctl = rs_ioctl,
472	.throttle = rs_throttle,
473	.unthrottle = rs_unthrottle,
474	.send_xchar = rs_send_xchar,
475	.hangup = rs_hangup,
476	.proc_fops = &rs_proc_fops,
477};
478
479static const struct tty_port_operations hp_port_ops = {
480	.activate = activate,
481	.shutdown = shutdown,
482};
483
484static int __init simrs_init(void)
485{
486	struct serial_state *state;
487	int retval;
488
489	if (!ia64_platform_is("hpsim"))
490		return -ENODEV;
491
492	hp_simserial_driver = alloc_tty_driver(NR_PORTS);
493	if (!hp_simserial_driver)
494		return -ENOMEM;
495
496	printk(KERN_INFO "SimSerial driver with no serial options enabled\n");
497
498	/* Initialize the tty_driver structure */
499
500	hp_simserial_driver->driver_name = "simserial";
501	hp_simserial_driver->name = "ttyS";
502	hp_simserial_driver->major = TTY_MAJOR;
503	hp_simserial_driver->minor_start = 64;
504	hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
505	hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
506	hp_simserial_driver->init_termios = tty_std_termios;
507	hp_simserial_driver->init_termios.c_cflag =
508		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
509	hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
510	tty_set_operations(hp_simserial_driver, &hp_ops);
511
512	state = rs_table;
513	tty_port_init(&state->port);
514	state->port.ops = &hp_port_ops;
515	state->port.close_delay = 0; /* XXX really 0? */
516
517	retval = hpsim_get_irq(KEYBOARD_INTR);
518	if (retval < 0) {
519		printk(KERN_ERR "%s: out of interrupt vectors!\n",
520				__func__);
521		goto err_free_tty;
522	}
523
524	state->irq = retval;
525
526	/* the port is imaginary */
527	printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);
528
529	tty_port_link_device(&state->port, hp_simserial_driver, 0);
530	retval = tty_register_driver(hp_simserial_driver);
531	if (retval) {
532		printk(KERN_ERR "Couldn't register simserial driver\n");
533		goto err_free_tty;
534	}
535
536	return 0;
537err_free_tty:
538	put_tty_driver(hp_simserial_driver);
539	tty_port_destroy(&state->port);
540	return retval;
541}
542
543#ifndef MODULE
544__initcall(simrs_init);
545#endif
546