1/*
2 *  drivers/s390/char/sclp_con.c
3 *    SCLP line mode console driver
4 *
5 *  S390 version
6 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
8 *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
9 */
10
11#include <linux/kmod.h>
12#include <linux/console.h>
13#include <linux/init.h>
14#include <linux/timer.h>
15#include <linux/jiffies.h>
16#include <linux/bootmem.h>
17#include <linux/err.h>
18
19#include "sclp.h"
20#include "sclp_rw.h"
21#include "sclp_tty.h"
22
23#define SCLP_CON_PRINT_HEADER "sclp console driver: "
24
25#define sclp_console_major 4		/* TTYAUX_MAJOR */
26#define sclp_console_minor 64
27#define sclp_console_name  "ttyS"
28
29/* Lock to guard over changes to global variables */
30static spinlock_t sclp_con_lock;
31/* List of free pages that can be used for console output buffering */
32static struct list_head sclp_con_pages;
33/* List of full struct sclp_buffer structures ready for output */
34static struct list_head sclp_con_outqueue;
35/* Counter how many buffers are emitted (max 1) and how many */
36/* are on the output queue. */
37static int sclp_con_buffer_count;
38/* Pointer to current console buffer */
39static struct sclp_buffer *sclp_conbuf;
40/* Timer for delayed output of console messages */
41static struct timer_list sclp_con_timer;
42
43/* Output format for console messages */
44static unsigned short sclp_con_columns;
45static unsigned short sclp_con_width_htab;
46
47static void
48sclp_conbuf_callback(struct sclp_buffer *buffer, int rc)
49{
50	unsigned long flags;
51	void *page;
52
53	do {
54		page = sclp_unmake_buffer(buffer);
55		spin_lock_irqsave(&sclp_con_lock, flags);
56		/* Remove buffer from outqueue */
57		list_del(&buffer->list);
58		sclp_con_buffer_count--;
59		list_add_tail((struct list_head *) page, &sclp_con_pages);
60		/* Check if there is a pending buffer on the out queue. */
61		buffer = NULL;
62		if (!list_empty(&sclp_con_outqueue))
63			buffer = list_entry(sclp_con_outqueue.next,
64					    struct sclp_buffer, list);
65		spin_unlock_irqrestore(&sclp_con_lock, flags);
66	} while (buffer && sclp_emit_buffer(buffer, sclp_conbuf_callback));
67}
68
69static void
70sclp_conbuf_emit(void)
71{
72	struct sclp_buffer* buffer;
73	unsigned long flags;
74	int count;
75	int rc;
76
77	spin_lock_irqsave(&sclp_con_lock, flags);
78	buffer = sclp_conbuf;
79	sclp_conbuf = NULL;
80	if (buffer == NULL) {
81		spin_unlock_irqrestore(&sclp_con_lock, flags);
82		return;
83	}
84	list_add_tail(&buffer->list, &sclp_con_outqueue);
85	count = sclp_con_buffer_count++;
86	spin_unlock_irqrestore(&sclp_con_lock, flags);
87	if (count)
88		return;
89	rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
90	if (rc)
91		sclp_conbuf_callback(buffer, rc);
92}
93
94/*
95 * When this routine is called from the timer then we flush the
96 * temporary write buffer without further waiting on a final new line.
97 */
98static void
99sclp_console_timeout(unsigned long data)
100{
101	sclp_conbuf_emit();
102}
103
104/*
105 * Writes the given message to S390 system console
106 */
107static void
108sclp_console_write(struct console *console, const char *message,
109		   unsigned int count)
110{
111	unsigned long flags;
112	void *page;
113	int written;
114
115	if (count == 0)
116		return;
117	spin_lock_irqsave(&sclp_con_lock, flags);
118	/*
119	 * process escape characters, write message into buffer,
120	 * send buffer to SCLP
121	 */
122	do {
123		/* make sure we have a console output buffer */
124		if (sclp_conbuf == NULL) {
125			while (list_empty(&sclp_con_pages)) {
126				spin_unlock_irqrestore(&sclp_con_lock, flags);
127				sclp_sync_wait();
128				spin_lock_irqsave(&sclp_con_lock, flags);
129			}
130			page = sclp_con_pages.next;
131			list_del((struct list_head *) page);
132			sclp_conbuf = sclp_make_buffer(page, sclp_con_columns,
133						       sclp_con_width_htab);
134		}
135		/* try to write the string to the current output buffer */
136		written = sclp_write(sclp_conbuf, (const unsigned char *)
137				     message, count);
138		if (written == count)
139			break;
140		/*
141		 * Not all characters could be written to the current
142		 * output buffer. Emit the buffer, create a new buffer
143		 * and then output the rest of the string.
144		 */
145		spin_unlock_irqrestore(&sclp_con_lock, flags);
146		sclp_conbuf_emit();
147		spin_lock_irqsave(&sclp_con_lock, flags);
148		message += written;
149		count -= written;
150	} while (count > 0);
151	/* Setup timer to output current console buffer after 1/10 second */
152	if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
153	    !timer_pending(&sclp_con_timer)) {
154		init_timer(&sclp_con_timer);
155		sclp_con_timer.function = sclp_console_timeout;
156		sclp_con_timer.data = 0UL;
157		sclp_con_timer.expires = jiffies + HZ/10;
158		add_timer(&sclp_con_timer);
159	}
160	spin_unlock_irqrestore(&sclp_con_lock, flags);
161}
162
163static struct tty_driver *
164sclp_console_device(struct console *c, int *index)
165{
166	*index = c->index;
167	return sclp_tty_driver;
168}
169
170/*
171 * This routine is called from panic when the kernel
172 * is going to give up. We have to make sure that all buffers
173 * will be flushed to the SCLP.
174 */
175static void
176sclp_console_unblank(void)
177{
178	unsigned long flags;
179
180	sclp_conbuf_emit();
181	spin_lock_irqsave(&sclp_con_lock, flags);
182	if (timer_pending(&sclp_con_timer))
183		del_timer(&sclp_con_timer);
184	while (sclp_con_buffer_count > 0) {
185		spin_unlock_irqrestore(&sclp_con_lock, flags);
186		sclp_sync_wait();
187		spin_lock_irqsave(&sclp_con_lock, flags);
188	}
189	spin_unlock_irqrestore(&sclp_con_lock, flags);
190}
191
192/*
193 * used to register the SCLP console to the kernel and to
194 * give printk necessary information
195 */
196static struct console sclp_console =
197{
198	.name = sclp_console_name,
199	.write = sclp_console_write,
200	.device = sclp_console_device,
201	.unblank = sclp_console_unblank,
202	.flags = CON_PRINTBUFFER,
203	.index = 0 /* ttyS0 */
204};
205
206/*
207 * called by console_init() in drivers/char/tty_io.c at boot-time.
208 */
209static int __init
210sclp_console_init(void)
211{
212	void *page;
213	int i;
214	int rc;
215
216	if (!CONSOLE_IS_SCLP)
217		return 0;
218	rc = sclp_rw_init();
219	if (rc)
220		return rc;
221	/* Allocate pages for output buffering */
222	INIT_LIST_HEAD(&sclp_con_pages);
223	for (i = 0; i < MAX_CONSOLE_PAGES; i++) {
224		page = alloc_bootmem_low_pages(PAGE_SIZE);
225		if (page == NULL)
226			return -ENOMEM;
227		list_add_tail((struct list_head *) page, &sclp_con_pages);
228	}
229	INIT_LIST_HEAD(&sclp_con_outqueue);
230	spin_lock_init(&sclp_con_lock);
231	sclp_con_buffer_count = 0;
232	sclp_conbuf = NULL;
233	init_timer(&sclp_con_timer);
234
235	/* Set output format */
236	if (MACHINE_IS_VM)
237		/*
238		 * save 4 characters for the CPU number
239		 * written at start of each line by VM/CP
240		 */
241		sclp_con_columns = 76;
242	else
243		sclp_con_columns = 80;
244	sclp_con_width_htab = 8;
245
246	/* enable printk-access to this driver */
247	register_console(&sclp_console);
248	return 0;
249}
250
251console_initcall(sclp_console_init);
252