aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/s390/char/sclp_con.c
blob: 5880def98fc1be4dbfedbfa166d725a52ffc35c2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
/*
 * SCLP line mode console driver
 *
 * Copyright IBM Corp. 1999, 2009
 * Author(s): Martin Peschke <mpeschke@de.ibm.com>
 *	      Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#include <linux/kmod.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/termios.h>
#include <linux/err.h>
#include <linux/reboot.h>
#include <linux/gfp.h>

#include "sclp.h"
#include "sclp_rw.h"
#include "sclp_tty.h"

#define sclp_console_major 4		/* TTYAUX_MAJOR */
#define sclp_console_minor 64
#define sclp_console_name  "ttyS"

/* Lock to guard over changes to global variables */
static spinlock_t sclp_con_lock;
/* List of free pages that can be used for console output buffering */
static struct list_head sclp_con_pages;
/* List of full struct sclp_buffer structures ready for output */
static struct list_head sclp_con_outqueue;
/* Pointer to current console buffer */
static struct sclp_buffer *sclp_conbuf;
/* Timer for delayed output of console messages */
static struct timer_list sclp_con_timer;
/* Suspend mode flag */
static int sclp_con_suspended;
/* Flag that output queue is currently running */
static int sclp_con_queue_running;

/* Output format for console messages */
static unsigned short sclp_con_columns;
static unsigned short sclp_con_width_htab;

static void
sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
{
	unsigned long flags;
	void *page;

	do {
		page = sclp_unmake_buffer(buffer);
		spin_lock_irqsave(&sclp_con_lock, flags);

		/* Remove buffer from outqueue */
		list_del(&buffer->list);
		list_add_tail((struct list_head *) page, &sclp_con_pages);

		/* Check if there is a pending buffer on the out queue. */
		buffer = NULL;
		if (!list_empty(&sclp_con_outqueue))
			buffer = list_first_entry(&sclp_con_outqueue,
						  struct sclp_buffer, list);
		if (!buffer || sclp_con_suspended) {
			sclp_con_queue_running = 0;
			spin_unlock_irqrestore(&sclp_con_lock, flags);
			break;
		}
		spin_unlock_irqrestore(&sclp_con_lock, flags);
	} while (sclp_emit_buffer(buffer, sclp_conbuf_callback));
}

/*
 * Finalize and emit first pending buffer.
 */
static void sclp_conbuf_emit(void)
{
	struct sclp_buffer* buffer;
	unsigned long flags;
	int rc;

	spin_lock_irqsave(&sclp_con_lock, flags);
	if (sclp_conbuf)
		list_add_tail(&sclp_conbuf->list, &sclp_con_outqueue);
	sclp_conbuf = NULL;
	if (sclp_con_queue_running || sclp_con_suspended)
		goto out_unlock;
	if (list_empty(&sclp_con_outqueue))
		goto out_unlock;
	buffer = list_first_entry(&sclp_con_outqueue, struct sclp_buffer,
				  list);
	sclp_con_queue_running = 1;
	spin_unlock_irqrestore(&sclp_con_lock, flags);

	rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
	if (rc)
		sclp_conbuf_callback(buffer, rc);
	return;
out_unlock:
	spin_unlock_irqrestore(&sclp_con_lock, flags);
}

/*
 * Wait until out queue is empty
 */
static void sclp_console_sync_queue(void)
{
	unsigned long flags;

	spin_lock_irqsave(&sclp_con_lock, flags);
	if (timer_pending(&sclp_con_timer))
		del_timer(&sclp_con_timer);
	while (sclp_con_queue_running) {
		spin_unlock_irqrestore(&sclp_con_lock, flags);
		sclp_sync_wait();
		spin_lock_irqsave(&sclp_con_lock, flags);
	}
	spin_unlock_irqrestore(&sclp_con_lock, flags);
}

/*
 * When this routine is called from the timer then we flush the
 * temporary write buffer without further waiting on a final new line.
 */
static void
sclp_console_timeout(unsigned long data)
{
	sclp_conbuf_emit();
}

/*
 * Drop oldest console buffer if sclp_con_drop is set
 */
static int
sclp_console_drop_buffer(void)
{
	struct list_head *list;
	struct sclp_buffer *buffer;
	void *page;

	if (!sclp_console_drop)
		return 0;
	list = sclp_con_outqueue.next;
	if (sclp_con_queue_running)
		/* The first element is in I/O */
		list = list->next;
	if (list == &sclp_con_outqueue)
		return 0;
	list_del(list);
	buffer = list_entry(list, struct sclp_buffer, list);
	page = sclp_unmake_buffer(buffer);
	list_add_tail((struct list_head *) page, &sclp_con_pages);
	return 1;
}

/*
 * Writes the given message to S390 system console
 */
static void
sclp_console_write(struct console *console, const char *message,
		   unsigned int count)
{
	unsigned long flags;
	void *page;
	int written;

	if (count == 0)
		return;
	spin_lock_irqsave(&sclp_con_lock, flags);
	/*
	 * process escape characters, write message into buffer,
	 * send buffer to SCLP
	 */
	do {
		/* make sure we have a console output buffer */
		if (sclp_conbuf == NULL) {
			if (list_empty(&sclp_con_pages))
				sclp_console_full++;
			while (list_empty(&sclp_con_pages)) {
				if (sclp_con_suspended)
					goto out;
				if (sclp_console_drop_buffer())
					break;
				spin_unlock_irqrestore(&sclp_con_lock, flags);
				sclp_sync_wait();
				spin_lock_irqsave(&sclp_con_lock, flags);
			}
			page = sclp_con_pages.next;
			list_del((struct list_head *) page);
			sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
						       sclp_con_width_htab);
		}
		/* try to write the string to the current output buffer */
		written = sclp_write(sclp_conbuf, (const unsigned char *)
				     message, count);
		if (written == count)
			break;
		/*
		 * Not all characters could be written to the current
		 * output buffer. Emit the buffer, create a new buffer
		 * and then output the rest of the string.
		 */
		spin_unlock_irqrestore(&sclp_con_lock, flags);
		sclp_conbuf_emit();
		spin_lock_irqsave(&sclp_con_lock, flags);
		message += written;
		count -= written;
	} while (count > 0);
	/* Setup timer to output current console buffer after 1/10 second */
	if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
	    !timer_pending(&sclp_con_timer)) {
		init_timer(&sclp_con_timer);
		sclp_con_timer.function = sclp_console_timeout;
		sclp_con_timer.data = 0UL;
		sclp_con_timer.expires = jiffies + HZ/10;
		add_timer(&sclp_con_timer);
	}
out:
	spin_unlock_irqrestore(&sclp_con_lock, flags);
}

static struct tty_driver *
sclp_console_device(struct console *c, int *index)
{
	*index = c->index;
	return sclp_tty_driver;
}

/*
 * Make sure that all buffers will be flushed to the SCLP.
 */
static void
sclp_console_flush(void)
{
	sclp_conbuf_emit();
	sclp_console_sync_queue();
}

/*
 * Resume console: If there are cached messages, emit them.
 */
static void sclp_console_resume(void)
{
	unsigned long flags;

	spin_lock_irqsave(&sclp_con_lock, flags);
	sclp_con_suspended = 0;
	spin_unlock_irqrestore(&sclp_con_lock, flags);
	sclp_conbuf_emit();
}

/*
 * Suspend console: Set suspend flag and flush console
 */
static void sclp_console_suspend(void)
{
	unsigned long flags;

	spin_lock_irqsave(&sclp_con_lock, flags);
	sclp_con_suspended = 1;
	spin_unlock_irqrestore(&sclp_con_lock, flags);
	sclp_console_flush();
}

static int sclp_console_notify(struct notifier_block *self,
			       unsigned long event, void *data)
{
	sclp_console_flush();
	return NOTIFY_OK;
}

static struct notifier_block on_panic_nb = {
	.notifier_call = sclp_console_notify,
	.priority = SCLP_PANIC_PRIO_CLIENT,
};

static struct notifier_block on_reboot_nb = {
	.notifier_call = sclp_console_notify,
	.priority = 1,
};

/*
 * used to register the SCLP console to the kernel and to
 * give printk necessary information
 */
static struct console sclp_console =
{
	.name = sclp_console_name,
	.write = sclp_console_write,
	.device = sclp_console_device,
	.flags = CON_PRINTBUFFER,
	.index = 0 /* ttyS0 */
};

/*
 * This function is called for SCLP suspend and resume events.
 */
void sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)
{
	switch (sclp_pm_event) {
	case SCLP_PM_EVENT_FREEZE:
		sclp_console_suspend();
		break;
	case SCLP_PM_EVENT_RESTORE:
	case SCLP_PM_EVENT_THAW:
		sclp_console_resume();
		break;
	}
}

/*
 * called by console_init() in drivers/char/tty_io.c at boot-time.
 */
static int __init
sclp_console_init(void)
{
	void *page;
	int i;
	int rc;

	if (!CONSOLE_IS_SCLP)
		return 0;
	rc = sclp_rw_init();
	if (rc)
		return rc;
	/* Allocate pages for output buffering */
	INIT_LIST_HEAD(&sclp_con_pages);
	for (i = 0; i < sclp_console_pages; i++) {
		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
		list_add_tail(page, &sclp_con_pages);
	}
	INIT_LIST_HEAD(&sclp_con_outqueue);
	spin_lock_init(&sclp_con_lock);
	sclp_conbuf = NULL;
	init_timer(&sclp_con_timer);

	/* Set output format */
	if (MACHINE_IS_VM)
		/*
		 * save 4 characters for the CPU number
		 * written at start of each line by VM/CP
		 */
		sclp_con_columns = 76;
	else
		sclp_con_columns = 80;
	sclp_con_width_htab = 8;

	/* enable printk-access to this driver */
	atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
	register_reboot_notifier(&on_reboot_nb);
	register_console(&sclp_console);
	return 0;
}

console_initcall(sclp_console_init);