1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * SCLP line mode console driver
4 *
5 * Copyright IBM Corp. 1999, 2009
6 * Author(s): Martin Peschke <mpeschke@de.ibm.com>
7 * Martin Schwidefsky <schwidefsky@de.ibm.com>
8 */
9
10 #include <linux/kmod.h>
11 #include <linux/console.h>
12 #include <linux/init.h>
13 #include <linux/timer.h>
14 #include <linux/jiffies.h>
15 #include <linux/termios.h>
16 #include <linux/err.h>
17 #include <linux/reboot.h>
18 #include <linux/gfp.h>
19
20 #include "sclp.h"
21 #include "sclp_rw.h"
22 #include "sclp_tty.h"
23
24 #define sclp_console_major 4 /* TTYAUX_MAJOR */
25 #define sclp_console_minor 64
26 #define sclp_console_name "ttyS"
27
28 /* Lock to guard over changes to global variables */
29 static DEFINE_SPINLOCK(sclp_con_lock);
30 /* List of free pages that can be used for console output buffering */
31 static LIST_HEAD(sclp_con_pages);
32 /* List of full struct sclp_buffer structures ready for output */
33 static LIST_HEAD(sclp_con_outqueue);
34 /* Pointer to current console buffer */
35 static struct sclp_buffer *sclp_conbuf;
36 /* Timer for delayed output of console messages */
37 static struct timer_list sclp_con_timer;
38 /* Suspend mode flag */
39 static int sclp_con_suspended;
40 /* Flag that output queue is currently running */
41 static int sclp_con_queue_running;
42
43 /* Output format for console messages */
44 #define SCLP_CON_COLUMNS 320
45 #define SPACES_PER_TAB 8
46
47 static void
sclp_conbuf_callback(struct sclp_buffer * buffer,int rc)48 sclp_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
57 /* Remove buffer from outqueue */
58 list_del(&buffer->list);
59 list_add_tail((struct list_head *) page, &sclp_con_pages);
60
61 /* Check if there is a pending buffer on the out queue. */
62 buffer = NULL;
63 if (!list_empty(&sclp_con_outqueue))
64 buffer = list_first_entry(&sclp_con_outqueue,
65 struct sclp_buffer, list);
66 if (!buffer || sclp_con_suspended) {
67 sclp_con_queue_running = 0;
68 spin_unlock_irqrestore(&sclp_con_lock, flags);
69 break;
70 }
71 spin_unlock_irqrestore(&sclp_con_lock, flags);
72 } while (sclp_emit_buffer(buffer, sclp_conbuf_callback));
73 }
74
75 /*
76 * Finalize and emit first pending buffer.
77 */
sclp_conbuf_emit(void)78 static void sclp_conbuf_emit(void)
79 {
80 struct sclp_buffer* buffer;
81 unsigned long flags;
82 int rc;
83
84 spin_lock_irqsave(&sclp_con_lock, flags);
85 if (sclp_conbuf)
86 list_add_tail(&sclp_conbuf->list, &sclp_con_outqueue);
87 sclp_conbuf = NULL;
88 if (sclp_con_queue_running || sclp_con_suspended)
89 goto out_unlock;
90 if (list_empty(&sclp_con_outqueue))
91 goto out_unlock;
92 buffer = list_first_entry(&sclp_con_outqueue, struct sclp_buffer,
93 list);
94 sclp_con_queue_running = 1;
95 spin_unlock_irqrestore(&sclp_con_lock, flags);
96
97 rc = sclp_emit_buffer(buffer, sclp_conbuf_callback);
98 if (rc)
99 sclp_conbuf_callback(buffer, rc);
100 return;
101 out_unlock:
102 spin_unlock_irqrestore(&sclp_con_lock, flags);
103 }
104
105 /*
106 * Wait until out queue is empty
107 */
sclp_console_sync_queue(void)108 static void sclp_console_sync_queue(void)
109 {
110 unsigned long flags;
111
112 spin_lock_irqsave(&sclp_con_lock, flags);
113 if (timer_pending(&sclp_con_timer))
114 del_timer(&sclp_con_timer);
115 while (sclp_con_queue_running) {
116 spin_unlock_irqrestore(&sclp_con_lock, flags);
117 sclp_sync_wait();
118 spin_lock_irqsave(&sclp_con_lock, flags);
119 }
120 spin_unlock_irqrestore(&sclp_con_lock, flags);
121 }
122
123 /*
124 * When this routine is called from the timer then we flush the
125 * temporary write buffer without further waiting on a final new line.
126 */
127 static void
sclp_console_timeout(struct timer_list * unused)128 sclp_console_timeout(struct timer_list *unused)
129 {
130 sclp_conbuf_emit();
131 }
132
133 /*
134 * Drop oldest console buffer if sclp_con_drop is set
135 */
136 static int
sclp_console_drop_buffer(void)137 sclp_console_drop_buffer(void)
138 {
139 struct list_head *list;
140 struct sclp_buffer *buffer;
141 void *page;
142
143 if (!sclp_console_drop)
144 return 0;
145 list = sclp_con_outqueue.next;
146 if (sclp_con_queue_running)
147 /* The first element is in I/O */
148 list = list->next;
149 if (list == &sclp_con_outqueue)
150 return 0;
151 list_del(list);
152 buffer = list_entry(list, struct sclp_buffer, list);
153 page = sclp_unmake_buffer(buffer);
154 list_add_tail((struct list_head *) page, &sclp_con_pages);
155 return 1;
156 }
157
158 /*
159 * Writes the given message to S390 system console
160 */
161 static void
sclp_console_write(struct console * console,const char * message,unsigned int count)162 sclp_console_write(struct console *console, const char *message,
163 unsigned int count)
164 {
165 unsigned long flags;
166 void *page;
167 int written;
168
169 if (count == 0)
170 return;
171 spin_lock_irqsave(&sclp_con_lock, flags);
172 /*
173 * process escape characters, write message into buffer,
174 * send buffer to SCLP
175 */
176 do {
177 /* make sure we have a console output buffer */
178 if (sclp_conbuf == NULL) {
179 if (list_empty(&sclp_con_pages))
180 sclp_console_full++;
181 while (list_empty(&sclp_con_pages)) {
182 if (sclp_con_suspended)
183 goto out;
184 if (sclp_console_drop_buffer())
185 break;
186 spin_unlock_irqrestore(&sclp_con_lock, flags);
187 sclp_sync_wait();
188 spin_lock_irqsave(&sclp_con_lock, flags);
189 }
190 page = sclp_con_pages.next;
191 list_del((struct list_head *) page);
192 sclp_conbuf = sclp_make_buffer(page, SCLP_CON_COLUMNS,
193 SPACES_PER_TAB);
194 }
195 /* try to write the string to the current output buffer */
196 written = sclp_write(sclp_conbuf, (const unsigned char *)
197 message, count);
198 if (written == count)
199 break;
200 /*
201 * Not all characters could be written to the current
202 * output buffer. Emit the buffer, create a new buffer
203 * and then output the rest of the string.
204 */
205 spin_unlock_irqrestore(&sclp_con_lock, flags);
206 sclp_conbuf_emit();
207 spin_lock_irqsave(&sclp_con_lock, flags);
208 message += written;
209 count -= written;
210 } while (count > 0);
211 /* Setup timer to output current console buffer after 1/10 second */
212 if (sclp_conbuf != NULL && sclp_chars_in_buffer(sclp_conbuf) != 0 &&
213 !timer_pending(&sclp_con_timer)) {
214 mod_timer(&sclp_con_timer, jiffies + HZ / 10);
215 }
216 out:
217 spin_unlock_irqrestore(&sclp_con_lock, flags);
218 }
219
220 static struct tty_driver *
sclp_console_device(struct console * c,int * index)221 sclp_console_device(struct console *c, int *index)
222 {
223 *index = c->index;
224 return sclp_tty_driver;
225 }
226
227 /*
228 * Make sure that all buffers will be flushed to the SCLP.
229 */
230 static void
sclp_console_flush(void)231 sclp_console_flush(void)
232 {
233 sclp_conbuf_emit();
234 sclp_console_sync_queue();
235 }
236
237 /*
238 * Resume console: If there are cached messages, emit them.
239 */
sclp_console_resume(void)240 static void sclp_console_resume(void)
241 {
242 unsigned long flags;
243
244 spin_lock_irqsave(&sclp_con_lock, flags);
245 sclp_con_suspended = 0;
246 spin_unlock_irqrestore(&sclp_con_lock, flags);
247 sclp_conbuf_emit();
248 }
249
250 /*
251 * Suspend console: Set suspend flag and flush console
252 */
sclp_console_suspend(void)253 static void sclp_console_suspend(void)
254 {
255 unsigned long flags;
256
257 spin_lock_irqsave(&sclp_con_lock, flags);
258 sclp_con_suspended = 1;
259 spin_unlock_irqrestore(&sclp_con_lock, flags);
260 sclp_console_flush();
261 }
262
sclp_console_notify(struct notifier_block * self,unsigned long event,void * data)263 static int sclp_console_notify(struct notifier_block *self,
264 unsigned long event, void *data)
265 {
266 sclp_console_flush();
267 return NOTIFY_OK;
268 }
269
270 static struct notifier_block on_panic_nb = {
271 .notifier_call = sclp_console_notify,
272 .priority = SCLP_PANIC_PRIO_CLIENT,
273 };
274
275 static struct notifier_block on_reboot_nb = {
276 .notifier_call = sclp_console_notify,
277 .priority = 1,
278 };
279
280 /*
281 * used to register the SCLP console to the kernel and to
282 * give printk necessary information
283 */
284 static struct console sclp_console =
285 {
286 .name = sclp_console_name,
287 .write = sclp_console_write,
288 .device = sclp_console_device,
289 .flags = CON_PRINTBUFFER,
290 .index = 0 /* ttyS0 */
291 };
292
293 /*
294 * This function is called for SCLP suspend and resume events.
295 */
sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)296 void sclp_console_pm_event(enum sclp_pm_event sclp_pm_event)
297 {
298 switch (sclp_pm_event) {
299 case SCLP_PM_EVENT_FREEZE:
300 sclp_console_suspend();
301 break;
302 case SCLP_PM_EVENT_RESTORE:
303 case SCLP_PM_EVENT_THAW:
304 sclp_console_resume();
305 break;
306 }
307 }
308
309 /*
310 * called by console_init() in drivers/char/tty_io.c at boot-time.
311 */
312 static int __init
sclp_console_init(void)313 sclp_console_init(void)
314 {
315 void *page;
316 int i;
317 int rc;
318
319 /* SCLP consoles are handled together */
320 if (!(CONSOLE_IS_SCLP || CONSOLE_IS_VT220))
321 return 0;
322 rc = sclp_rw_init();
323 if (rc)
324 return rc;
325 /* Allocate pages for output buffering */
326 for (i = 0; i < sclp_console_pages; i++) {
327 page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
328 list_add_tail(page, &sclp_con_pages);
329 }
330 sclp_conbuf = NULL;
331 timer_setup(&sclp_con_timer, sclp_console_timeout, 0);
332
333 /* enable printk-access to this driver */
334 atomic_notifier_chain_register(&panic_notifier_list, &on_panic_nb);
335 register_reboot_notifier(&on_reboot_nb);
336 register_console(&sclp_console);
337 return 0;
338 }
339
340 console_initcall(sclp_console_init);
341