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
 33#include <plat/mailbox.h>
 34
 35static struct omap_mbox **mboxes;
 36
 37static int mbox_configured;
 38static DEFINE_MUTEX(mbox_configured_lock);
 39
 40static unsigned int mbox_kfifo_size = CONFIG_OMAP_MBOX_KFIFO_SIZE;
 41module_param(mbox_kfifo_size, uint, S_IRUGO);
 42MODULE_PARM_DESC(mbox_kfifo_size, "Size of omap's mailbox kfifo (bytes)");
 43
 44/* Mailbox FIFO handle functions */
 45static inline mbox_msg_t mbox_fifo_read(struct omap_mbox *mbox)
 46{
 47	return mbox->ops->fifo_read(mbox);
 48}
 49static inline void mbox_fifo_write(struct omap_mbox *mbox, mbox_msg_t msg)
 50{
 51	mbox->ops->fifo_write(mbox, msg);
 52}
 53static inline int mbox_fifo_empty(struct omap_mbox *mbox)
 54{
 55	return mbox->ops->fifo_empty(mbox);
 56}
 57static inline int mbox_fifo_full(struct omap_mbox *mbox)
 58{
 59	return mbox->ops->fifo_full(mbox);
 60}
 61
 62/* Mailbox IRQ handle functions */
 63static inline void ack_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 64{
 65	if (mbox->ops->ack_irq)
 66		mbox->ops->ack_irq(mbox, irq);
 67}
 68static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 69{
 70	return mbox->ops->is_irq(mbox, irq);
 71}
 72
 73/*
 74 * message sender
 75 */
 76static int __mbox_poll_for_space(struct omap_mbox *mbox)
 77{
 78	int ret = 0, i = 1000;
 79
 80	while (mbox_fifo_full(mbox)) {
 81		if (mbox->ops->type == OMAP_MBOX_TYPE2)
 82			return -1;
 83		if (--i == 0)
 84			return -1;
 85		udelay(1);
 86	}
 87	return ret;
 88}
 89
 90int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
 91{
 92	struct omap_mbox_queue *mq = mbox->txq;
 93	int ret = 0, len;
 94
 95	spin_lock_bh(&mq->lock);
 96
 97	if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
 98		ret = -ENOMEM;
 99		goto out;
100	}
101
102	if (kfifo_is_empty(&mq->fifo) && !__mbox_poll_for_space(mbox)) {
103		mbox_fifo_write(mbox, msg);
104		goto out;
105	}
106
107	len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
108	WARN_ON(len != sizeof(msg));
109
110	tasklet_schedule(&mbox->txq->tasklet);
111
112out:
113	spin_unlock_bh(&mq->lock);
114	return ret;
115}
116EXPORT_SYMBOL(omap_mbox_msg_send);
117
118static void mbox_tx_tasklet(unsigned long tx_data)
119{
120	struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
121	struct omap_mbox_queue *mq = mbox->txq;
122	mbox_msg_t msg;
123	int ret;
124
125	while (kfifo_len(&mq->fifo)) {
126		if (__mbox_poll_for_space(mbox)) {
127			omap_mbox_enable_irq(mbox, IRQ_TX);
128			break;
129		}
130
131		ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
132								sizeof(msg));
133		WARN_ON(ret != sizeof(msg));
134
135		mbox_fifo_write(mbox, msg);
136	}
137}
138
139/*
140 * Message receiver(workqueue)
141 */
142static void mbox_rx_work(struct work_struct *work)
143{
144	struct omap_mbox_queue *mq =
145			container_of(work, struct omap_mbox_queue, work);
146	mbox_msg_t msg;
147	int len;
148
149	while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
150		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
151		WARN_ON(len != sizeof(msg));
152
153		blocking_notifier_call_chain(&mq->mbox->notifier, len,
154								(void *)msg);
155		spin_lock_irq(&mq->lock);
156		if (mq->full) {
157			mq->full = false;
158			omap_mbox_enable_irq(mq->mbox, IRQ_RX);
159		}
160		spin_unlock_irq(&mq->lock);
161	}
162}
163
164/*
165 * Mailbox interrupt handler
166 */
167static void __mbox_tx_interrupt(struct omap_mbox *mbox)
168{
169	omap_mbox_disable_irq(mbox, IRQ_TX);
170	ack_mbox_irq(mbox, IRQ_TX);
171	tasklet_schedule(&mbox->txq->tasklet);
172}
173
174static void __mbox_rx_interrupt(struct omap_mbox *mbox)
175{
176	struct omap_mbox_queue *mq = mbox->rxq;
177	mbox_msg_t msg;
178	int len;
179
180	while (!mbox_fifo_empty(mbox)) {
181		if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg))) {
182			omap_mbox_disable_irq(mbox, IRQ_RX);
183			mq->full = true;
184			goto nomem;
185		}
186
187		msg = mbox_fifo_read(mbox);
188
189		len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
190		WARN_ON(len != sizeof(msg));
191
192		if (mbox->ops->type == OMAP_MBOX_TYPE1)
193			break;
194	}
195
196	/* no more messages in the fifo. clear IRQ source. */
197	ack_mbox_irq(mbox, IRQ_RX);
198nomem:
199	schedule_work(&mbox->rxq->work);
200}
201
202static irqreturn_t mbox_interrupt(int irq, void *p)
203{
204	struct omap_mbox *mbox = p;
205
206	if (is_mbox_irq(mbox, IRQ_TX))
207		__mbox_tx_interrupt(mbox);
208
209	if (is_mbox_irq(mbox, IRQ_RX))
210		__mbox_rx_interrupt(mbox);
211
212	return IRQ_HANDLED;
213}
214
215static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
216					void (*work) (struct work_struct *),
217					void (*tasklet)(unsigned long))
218{
219	struct omap_mbox_queue *mq;
220
221	mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
222	if (!mq)
223		return NULL;
224
225	spin_lock_init(&mq->lock);
226
227	if (kfifo_alloc(&mq->fifo, mbox_kfifo_size, GFP_KERNEL))
228		goto error;
229
230	if (work)
231		INIT_WORK(&mq->work, work);
232
233	if (tasklet)
234		tasklet_init(&mq->tasklet, tasklet, (unsigned long)mbox);
235	return mq;
236error:
237	kfree(mq);
238	return NULL;
239}
240
241static void mbox_queue_free(struct omap_mbox_queue *q)
242{
243	kfifo_free(&q->fifo);
244	kfree(q);
245}
246
247static int omap_mbox_startup(struct omap_mbox *mbox)
248{
249	int ret = 0;
250	struct omap_mbox_queue *mq;
251
252	mutex_lock(&mbox_configured_lock);
253	if (!mbox_configured++) {
254		if (likely(mbox->ops->startup)) {
255			ret = mbox->ops->startup(mbox);
256			if (unlikely(ret))
257				goto fail_startup;
258		} else
259			goto fail_startup;
260	}
261
262	if (!mbox->use_count++) {
263		ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
264							mbox->name, mbox);
265		if (unlikely(ret)) {
266			pr_err("failed to register mailbox interrupt:%d\n",
267									ret);
268			goto fail_request_irq;
269		}
270		mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
271		if (!mq) {
272			ret = -ENOMEM;
273			goto fail_alloc_txq;
274		}
275		mbox->txq = mq;
276
277		mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
278		if (!mq) {
279			ret = -ENOMEM;
280			goto fail_alloc_rxq;
281		}
282		mbox->rxq = mq;
283		mq->mbox = mbox;
284	}
285	mutex_unlock(&mbox_configured_lock);
286	return 0;
287
288fail_alloc_rxq:
289	mbox_queue_free(mbox->txq);
290fail_alloc_txq:
291	free_irq(mbox->irq, mbox);
292fail_request_irq:
293	if (mbox->ops->shutdown)
294		mbox->ops->shutdown(mbox);
295	mbox->use_count--;
296fail_startup:
297	mbox_configured--;
298	mutex_unlock(&mbox_configured_lock);
299	return ret;
300}
301
302static void omap_mbox_fini(struct omap_mbox *mbox)
303{
304	mutex_lock(&mbox_configured_lock);
305
306	if (!--mbox->use_count) {
307		free_irq(mbox->irq, mbox);
308		tasklet_kill(&mbox->txq->tasklet);
309	flush_work_sync(&mbox->rxq->work);
310		mbox_queue_free(mbox->txq);
311		mbox_queue_free(mbox->rxq);
312	}
313
314	if (likely(mbox->ops->shutdown)) {
315		if (!--mbox_configured)
316			mbox->ops->shutdown(mbox);
317	}
318
319	mutex_unlock(&mbox_configured_lock);
320}
321
322struct omap_mbox *omap_mbox_get(const char *name, struct notifier_block *nb)
323{
324	struct omap_mbox *_mbox, *mbox = NULL;
325	int i, ret;
326
327	if (!mboxes)
328		return ERR_PTR(-EINVAL);
329
330	for (i = 0; (_mbox = mboxes[i]); i++) {
331		if (!strcmp(_mbox->name, name)) {
332			mbox = _mbox;
333			break;
334		}
335	}
336
337	if (!mbox)
338		return ERR_PTR(-ENOENT);
339
340	ret = omap_mbox_startup(mbox);
341	if (ret)
342		return ERR_PTR(-ENODEV);
343
344	if (nb)
345		blocking_notifier_chain_register(&mbox->notifier, nb);
346
347	return mbox;
348}
349EXPORT_SYMBOL(omap_mbox_get);
350
351void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb)
352{
353	blocking_notifier_chain_unregister(&mbox->notifier, nb);
354	omap_mbox_fini(mbox);
355}
356EXPORT_SYMBOL(omap_mbox_put);
357
358static struct class omap_mbox_class = { .name = "mbox", };
359
360int omap_mbox_register(struct device *parent, struct omap_mbox **list)
361{
362	int ret;
363	int i;
364
365	mboxes = list;
366	if (!mboxes)
367		return -EINVAL;
368
369	for (i = 0; mboxes[i]; i++) {
370		struct omap_mbox *mbox = mboxes[i];
371		mbox->dev = device_create(&omap_mbox_class,
372				parent, 0, mbox, "%s", mbox->name);
373		if (IS_ERR(mbox->dev)) {
374			ret = PTR_ERR(mbox->dev);
375			goto err_out;
376		}
377
378		BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
379	}
380	return 0;
381
382err_out:
383	while (i--)
384		device_unregister(mboxes[i]->dev);
385	return ret;
386}
387EXPORT_SYMBOL(omap_mbox_register);
388
389int omap_mbox_unregister(void)
390{
391	int i;
392
393	if (!mboxes)
394		return -EINVAL;
395
396	for (i = 0; mboxes[i]; i++)
397		device_unregister(mboxes[i]->dev);
398	mboxes = NULL;
399	return 0;
400}
401EXPORT_SYMBOL(omap_mbox_unregister);
402
403static int __init omap_mbox_init(void)
404{
405	int err;
406
407	err = class_register(&omap_mbox_class);
408	if (err)
409		return err;
410
411	/* kfifo size sanity check: alignment and minimal size */
412	mbox_kfifo_size = ALIGN(mbox_kfifo_size, sizeof(mbox_msg_t));
413	mbox_kfifo_size = max_t(unsigned int, mbox_kfifo_size,
414							sizeof(mbox_msg_t));
415
416	return 0;
417}
418subsys_initcall(omap_mbox_init);
419
420static void __exit omap_mbox_exit(void)
421{
422	class_unregister(&omap_mbox_class);
423}
424module_exit(omap_mbox_exit);
425
426MODULE_LICENSE("GPL v2");
427MODULE_DESCRIPTION("omap mailbox: interrupt driven messaging");
428MODULE_AUTHOR("Toshihiro Kobayashi");
429MODULE_AUTHOR("Hiroshi DOYU");