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1 /*
2  * OMAP mailbox driver
3  *
4  * Copyright (C) 2006-2009 Nokia Corporation. All rights reserved.
5  *
6  * Contact: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
7  *
8  * This program is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU General Public License
10  * version 2 as published by the Free Software Foundation.
11  *
12  * This program is distributed in the hope that it will be useful, but
13  * WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20  * 02110-1301 USA
21  *
22  */
23 
24 #include <linux/interrupt.h>
25 #include <linux/spinlock.h>
26 #include <linux/mutex.h>
27 #include <linux/delay.h>
28 #include <linux/slab.h>
29 #include <linux/kfifo.h>
30 #include <linux/err.h>
31 #include <linux/notifier.h>
32 #include <linux/module.h>
33 
34 #include <plat/mailbox.h>
35 
36 static struct omap_mbox **mboxes;
37 
38 static int mbox_configured;
39 static DEFINE_MUTEX(mbox_configured_lock);
40 
41 static unsigned int mbox_kfifo_size = CONFIG_OMAP_MBOX_KFIFO_SIZE;
42 module_param(mbox_kfifo_size, uint, S_IRUGO);
43 MODULE_PARM_DESC(mbox_kfifo_size, "Size of omap's mailbox kfifo (bytes)");
44 
45 /* Mailbox FIFO handle functions */
mbox_fifo_read(struct omap_mbox * mbox)46 static inline mbox_msg_t mbox_fifo_read(struct omap_mbox *mbox)
47 {
48 	return mbox->ops->fifo_read(mbox);
49 }
mbox_fifo_write(struct omap_mbox * mbox,mbox_msg_t msg)50 static inline void mbox_fifo_write(struct omap_mbox *mbox, mbox_msg_t msg)
51 {
52 	mbox->ops->fifo_write(mbox, msg);
53 }
mbox_fifo_empty(struct omap_mbox * mbox)54 static inline int mbox_fifo_empty(struct omap_mbox *mbox)
55 {
56 	return mbox->ops->fifo_empty(mbox);
57 }
mbox_fifo_full(struct omap_mbox * mbox)58 static inline int mbox_fifo_full(struct omap_mbox *mbox)
59 {
60 	return mbox->ops->fifo_full(mbox);
61 }
62 
63 /* Mailbox IRQ handle functions */
ack_mbox_irq(struct omap_mbox * mbox,omap_mbox_irq_t irq)64 static inline void ack_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
65 {
66 	if (mbox->ops->ack_irq)
67 		mbox->ops->ack_irq(mbox, irq);
68 }
is_mbox_irq(struct omap_mbox * mbox,omap_mbox_irq_t irq)69 static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
70 {
71 	return mbox->ops->is_irq(mbox, irq);
72 }
73 
74 /*
75  * message sender
76  */
__mbox_poll_for_space(struct omap_mbox * mbox)77 static int __mbox_poll_for_space(struct omap_mbox *mbox)
78 {
79 	int ret = 0, i = 1000;
80 
81 	while (mbox_fifo_full(mbox)) {
82 		if (mbox->ops->type == OMAP_MBOX_TYPE2)
83 			return -1;
84 		if (--i == 0)
85 			return -1;
86 		udelay(1);
87 	}
88 	return ret;
89 }
90 
omap_mbox_msg_send(struct omap_mbox * mbox,mbox_msg_t msg)91 int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
92 {
93 	struct omap_mbox_queue *mq = mbox->txq;
94 	int ret = 0, len;
95 
96 	spin_lock_bh(&mq->lock);
97 
98 	if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
99 		ret = -ENOMEM;
100 		goto out;
101 	}
102 
103 	if (kfifo_is_empty(&mq->fifo) && !__mbox_poll_for_space(mbox)) {
104 		mbox_fifo_write(mbox, msg);
105 		goto out;
106 	}
107 
108 	len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
109 	WARN_ON(len != sizeof(msg));
110 
111 	tasklet_schedule(&mbox->txq->tasklet);
112 
113 out:
114 	spin_unlock_bh(&mq->lock);
115 	return ret;
116 }
117 EXPORT_SYMBOL(omap_mbox_msg_send);
118 
mbox_tx_tasklet(unsigned long tx_data)119 static void mbox_tx_tasklet(unsigned long tx_data)
120 {
121 	struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
122 	struct omap_mbox_queue *mq = mbox->txq;
123 	mbox_msg_t msg;
124 	int ret;
125 
126 	while (kfifo_len(&mq->fifo)) {
127 		if (__mbox_poll_for_space(mbox)) {
128 			omap_mbox_enable_irq(mbox, IRQ_TX);
129 			break;
130 		}
131 
132 		ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
133 								sizeof(msg));
134 		WARN_ON(ret != sizeof(msg));
135 
136 		mbox_fifo_write(mbox, msg);
137 	}
138 }
139 
140 /*
141  * Message receiver(workqueue)
142  */
mbox_rx_work(struct work_struct * work)143 static void mbox_rx_work(struct work_struct *work)
144 {
145 	struct omap_mbox_queue *mq =
146 			container_of(work, struct omap_mbox_queue, work);
147 	mbox_msg_t msg;
148 	int len;
149 
150 	while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
151 		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
152 		WARN_ON(len != sizeof(msg));
153 
154 		blocking_notifier_call_chain(&mq->mbox->notifier, len,
155 								(void *)msg);
156 		spin_lock_irq(&mq->lock);
157 		if (mq->full) {
158 			mq->full = false;
159 			omap_mbox_enable_irq(mq->mbox, IRQ_RX);
160 		}
161 		spin_unlock_irq(&mq->lock);
162 	}
163 }
164 
165 /*
166  * Mailbox interrupt handler
167  */
__mbox_tx_interrupt(struct omap_mbox * mbox)168 static void __mbox_tx_interrupt(struct omap_mbox *mbox)
169 {
170 	omap_mbox_disable_irq(mbox, IRQ_TX);
171 	ack_mbox_irq(mbox, IRQ_TX);
172 	tasklet_schedule(&mbox->txq->tasklet);
173 }
174 
__mbox_rx_interrupt(struct omap_mbox * mbox)175 static void __mbox_rx_interrupt(struct omap_mbox *mbox)
176 {
177 	struct omap_mbox_queue *mq = mbox->rxq;
178 	mbox_msg_t msg;
179 	int len;
180 
181 	while (!mbox_fifo_empty(mbox)) {
182 		if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg))) {
183 			omap_mbox_disable_irq(mbox, IRQ_RX);
184 			mq->full = true;
185 			goto nomem;
186 		}
187 
188 		msg = mbox_fifo_read(mbox);
189 
190 		len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
191 		WARN_ON(len != sizeof(msg));
192 
193 		if (mbox->ops->type == OMAP_MBOX_TYPE1)
194 			break;
195 	}
196 
197 	/* no more messages in the fifo. clear IRQ source. */
198 	ack_mbox_irq(mbox, IRQ_RX);
199 nomem:
200 	schedule_work(&mbox->rxq->work);
201 }
202 
mbox_interrupt(int irq,void * p)203 static irqreturn_t mbox_interrupt(int irq, void *p)
204 {
205 	struct omap_mbox *mbox = p;
206 
207 	if (is_mbox_irq(mbox, IRQ_TX))
208 		__mbox_tx_interrupt(mbox);
209 
210 	if (is_mbox_irq(mbox, IRQ_RX))
211 		__mbox_rx_interrupt(mbox);
212 
213 	return IRQ_HANDLED;
214 }
215 
mbox_queue_alloc(struct omap_mbox * mbox,void (* work)(struct work_struct *),void (* tasklet)(unsigned long))216 static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
217 					void (*work) (struct work_struct *),
218 					void (*tasklet)(unsigned long))
219 {
220 	struct omap_mbox_queue *mq;
221 
222 	mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
223 	if (!mq)
224 		return NULL;
225 
226 	spin_lock_init(&mq->lock);
227 
228 	if (kfifo_alloc(&mq->fifo, mbox_kfifo_size, GFP_KERNEL))
229 		goto error;
230 
231 	if (work)
232 		INIT_WORK(&mq->work, work);
233 
234 	if (tasklet)
235 		tasklet_init(&mq->tasklet, tasklet, (unsigned long)mbox);
236 	return mq;
237 error:
238 	kfree(mq);
239 	return NULL;
240 }
241 
mbox_queue_free(struct omap_mbox_queue * q)242 static void mbox_queue_free(struct omap_mbox_queue *q)
243 {
244 	kfifo_free(&q->fifo);
245 	kfree(q);
246 }
247 
omap_mbox_startup(struct omap_mbox * mbox)248 static int omap_mbox_startup(struct omap_mbox *mbox)
249 {
250 	int ret = 0;
251 	struct omap_mbox_queue *mq;
252 
253 	mutex_lock(&mbox_configured_lock);
254 	if (!mbox_configured++) {
255 		if (likely(mbox->ops->startup)) {
256 			ret = mbox->ops->startup(mbox);
257 			if (unlikely(ret))
258 				goto fail_startup;
259 		} else
260 			goto fail_startup;
261 	}
262 
263 	if (!mbox->use_count++) {
264 		ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
265 							mbox->name, mbox);
266 		if (unlikely(ret)) {
267 			pr_err("failed to register mailbox interrupt:%d\n",
268 									ret);
269 			goto fail_request_irq;
270 		}
271 		mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
272 		if (!mq) {
273 			ret = -ENOMEM;
274 			goto fail_alloc_txq;
275 		}
276 		mbox->txq = mq;
277 
278 		mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
279 		if (!mq) {
280 			ret = -ENOMEM;
281 			goto fail_alloc_rxq;
282 		}
283 		mbox->rxq = mq;
284 		mq->mbox = mbox;
285 	}
286 	mutex_unlock(&mbox_configured_lock);
287 	return 0;
288 
289 fail_alloc_rxq:
290 	mbox_queue_free(mbox->txq);
291 fail_alloc_txq:
292 	free_irq(mbox->irq, mbox);
293 fail_request_irq:
294 	if (mbox->ops->shutdown)
295 		mbox->ops->shutdown(mbox);
296 	mbox->use_count--;
297 fail_startup:
298 	mbox_configured--;
299 	mutex_unlock(&mbox_configured_lock);
300 	return ret;
301 }
302 
omap_mbox_fini(struct omap_mbox * mbox)303 static void omap_mbox_fini(struct omap_mbox *mbox)
304 {
305 	mutex_lock(&mbox_configured_lock);
306 
307 	if (!--mbox->use_count) {
308 		free_irq(mbox->irq, mbox);
309 		tasklet_kill(&mbox->txq->tasklet);
310 		flush_work_sync(&mbox->rxq->work);
311 		mbox_queue_free(mbox->txq);
312 		mbox_queue_free(mbox->rxq);
313 	}
314 
315 	if (likely(mbox->ops->shutdown)) {
316 		if (!--mbox_configured)
317 			mbox->ops->shutdown(mbox);
318 	}
319 
320 	mutex_unlock(&mbox_configured_lock);
321 }
322 
omap_mbox_get(const char * name,struct notifier_block * nb)323 struct omap_mbox *omap_mbox_get(const char *name, struct notifier_block *nb)
324 {
325 	struct omap_mbox *_mbox, *mbox = NULL;
326 	int i, ret;
327 
328 	if (!mboxes)
329 		return ERR_PTR(-EINVAL);
330 
331 	for (i = 0; (_mbox = mboxes[i]); i++) {
332 		if (!strcmp(_mbox->name, name)) {
333 			mbox = _mbox;
334 			break;
335 		}
336 	}
337 
338 	if (!mbox)
339 		return ERR_PTR(-ENOENT);
340 
341 	ret = omap_mbox_startup(mbox);
342 	if (ret)
343 		return ERR_PTR(-ENODEV);
344 
345 	if (nb)
346 		blocking_notifier_chain_register(&mbox->notifier, nb);
347 
348 	return mbox;
349 }
350 EXPORT_SYMBOL(omap_mbox_get);
351 
omap_mbox_put(struct omap_mbox * mbox,struct notifier_block * nb)352 void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb)
353 {
354 	blocking_notifier_chain_unregister(&mbox->notifier, nb);
355 	omap_mbox_fini(mbox);
356 }
357 EXPORT_SYMBOL(omap_mbox_put);
358 
359 static struct class omap_mbox_class = { .name = "mbox", };
360 
omap_mbox_register(struct device * parent,struct omap_mbox ** list)361 int omap_mbox_register(struct device *parent, struct omap_mbox **list)
362 {
363 	int ret;
364 	int i;
365 
366 	mboxes = list;
367 	if (!mboxes)
368 		return -EINVAL;
369 
370 	for (i = 0; mboxes[i]; i++) {
371 		struct omap_mbox *mbox = mboxes[i];
372 		mbox->dev = device_create(&omap_mbox_class,
373 				parent, 0, mbox, "%s", mbox->name);
374 		if (IS_ERR(mbox->dev)) {
375 			ret = PTR_ERR(mbox->dev);
376 			goto err_out;
377 		}
378 
379 		BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
380 	}
381 	return 0;
382 
383 err_out:
384 	while (i--)
385 		device_unregister(mboxes[i]->dev);
386 	return ret;
387 }
388 EXPORT_SYMBOL(omap_mbox_register);
389 
omap_mbox_unregister(void)390 int omap_mbox_unregister(void)
391 {
392 	int i;
393 
394 	if (!mboxes)
395 		return -EINVAL;
396 
397 	for (i = 0; mboxes[i]; i++)
398 		device_unregister(mboxes[i]->dev);
399 	mboxes = NULL;
400 	return 0;
401 }
402 EXPORT_SYMBOL(omap_mbox_unregister);
403 
omap_mbox_init(void)404 static int __init omap_mbox_init(void)
405 {
406 	int err;
407 
408 	err = class_register(&omap_mbox_class);
409 	if (err)
410 		return err;
411 
412 	/* kfifo size sanity check: alignment and minimal size */
413 	mbox_kfifo_size = ALIGN(mbox_kfifo_size, sizeof(mbox_msg_t));
414 	mbox_kfifo_size = max_t(unsigned int, mbox_kfifo_size,
415 							sizeof(mbox_msg_t));
416 
417 	return 0;
418 }
419 subsys_initcall(omap_mbox_init);
420 
omap_mbox_exit(void)421 static void __exit omap_mbox_exit(void)
422 {
423 	class_unregister(&omap_mbox_class);
424 }
425 module_exit(omap_mbox_exit);
426 
427 MODULE_LICENSE("GPL v2");
428 MODULE_DESCRIPTION("omap mailbox: interrupt driven messaging");
429 MODULE_AUTHOR("Toshihiro Kobayashi");
430 MODULE_AUTHOR("Hiroshi DOYU");
431