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
 36static struct omap_mbox **mboxes;
 37
 38static int mbox_configured;
 39static DEFINE_MUTEX(mbox_configured_lock);
 40
 41static unsigned int mbox_kfifo_size = CONFIG_OMAP_MBOX_KFIFO_SIZE;
 42module_param(mbox_kfifo_size, uint, S_IRUGO);
 43MODULE_PARM_DESC(mbox_kfifo_size, "Size of omap's mailbox kfifo (bytes)");
 44
 45/* Mailbox FIFO handle functions */
 46static inline mbox_msg_t mbox_fifo_read(struct omap_mbox *mbox)
 47{
 48	return mbox->ops->fifo_read(mbox);
 49}
 50static inline void mbox_fifo_write(struct omap_mbox *mbox, mbox_msg_t msg)
 51{
 52	mbox->ops->fifo_write(mbox, msg);
 53}
 54static inline int mbox_fifo_empty(struct omap_mbox *mbox)
 55{
 56	return mbox->ops->fifo_empty(mbox);
 57}
 58static inline int mbox_fifo_full(struct omap_mbox *mbox)
 59{
 60	return mbox->ops->fifo_full(mbox);
 61}
 62
 63/* Mailbox IRQ handle functions */
 64static 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}
 69static 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 */
 77static 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
 91int 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
113out:
114	spin_unlock_bh(&mq->lock);
115	return ret;
116}
117EXPORT_SYMBOL(omap_mbox_msg_send);
118
119static 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 */
143static 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 */
168static 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
175static 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);
199nomem:
200	schedule_work(&mbox->rxq->work);
201}
202
203static 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
216static 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;
237error:
238	kfree(mq);
239	return NULL;
240}
241
242static void mbox_queue_free(struct omap_mbox_queue *q)
243{
244	kfifo_free(&q->fifo);
245	kfree(q);
246}
247
248static 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
289fail_alloc_rxq:
290	mbox_queue_free(mbox->txq);
291fail_alloc_txq:
292	free_irq(mbox->irq, mbox);
293fail_request_irq:
294	if (mbox->ops->shutdown)
295		mbox->ops->shutdown(mbox);
296	mbox->use_count--;
297fail_startup:
298	mbox_configured--;
299	mutex_unlock(&mbox_configured_lock);
300	return ret;
301}
302
303static 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
323struct 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}
350EXPORT_SYMBOL(omap_mbox_get);
351
352void 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}
357EXPORT_SYMBOL(omap_mbox_put);
358
359static struct class omap_mbox_class = { .name = "mbox", };
360
361int 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
383err_out:
384	while (i--)
385		device_unregister(mboxes[i]->dev);
386	return ret;
387}
388EXPORT_SYMBOL(omap_mbox_register);
389
390int 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}
402EXPORT_SYMBOL(omap_mbox_unregister);
403
404static 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}
419subsys_initcall(omap_mbox_init);
420
421static void __exit omap_mbox_exit(void)
422{
423	class_unregister(&omap_mbox_class);
424}
425module_exit(omap_mbox_exit);
426
427MODULE_LICENSE("GPL v2");
428MODULE_DESCRIPTION("omap mailbox: interrupt driven messaging");
429MODULE_AUTHOR("Toshihiro Kobayashi");
430MODULE_AUTHOR("Hiroshi DOYU");