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 "omap-mbox.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
119void omap_mbox_save_ctx(struct omap_mbox *mbox)
120{
121	if (!mbox->ops->save_ctx) {
122		dev_err(mbox->dev, "%s:\tno save\n", __func__);
123		return;
124	}
125
126	mbox->ops->save_ctx(mbox);
127}
128EXPORT_SYMBOL(omap_mbox_save_ctx);
129
130void omap_mbox_restore_ctx(struct omap_mbox *mbox)
131{
132	if (!mbox->ops->restore_ctx) {
133		dev_err(mbox->dev, "%s:\tno restore\n", __func__);
134		return;
135	}
136
137	mbox->ops->restore_ctx(mbox);
138}
139EXPORT_SYMBOL(omap_mbox_restore_ctx);
140
141void omap_mbox_enable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
142{
143	mbox->ops->enable_irq(mbox, irq);
144}
145EXPORT_SYMBOL(omap_mbox_enable_irq);
146
147void omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
148{
149	mbox->ops->disable_irq(mbox, irq);
150}
151EXPORT_SYMBOL(omap_mbox_disable_irq);
152
153static void mbox_tx_tasklet(unsigned long tx_data)
154{
155	struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
156	struct omap_mbox_queue *mq = mbox->txq;
157	mbox_msg_t msg;
158	int ret;
159
160	while (kfifo_len(&mq->fifo)) {
161		if (__mbox_poll_for_space(mbox)) {
162			omap_mbox_enable_irq(mbox, IRQ_TX);
163			break;
164		}
165
166		ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
167								sizeof(msg));
168		WARN_ON(ret != sizeof(msg));
169
170		mbox_fifo_write(mbox, msg);
171	}
172}
173
174/*
175 * Message receiver(workqueue)
176 */
177static void mbox_rx_work(struct work_struct *work)
178{
179	struct omap_mbox_queue *mq =
180			container_of(work, struct omap_mbox_queue, work);
181	mbox_msg_t msg;
182	int len;
183
184	while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
185		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
186		WARN_ON(len != sizeof(msg));
187
188		blocking_notifier_call_chain(&mq->mbox->notifier, len,
189								(void *)msg);
190		spin_lock_irq(&mq->lock);
191		if (mq->full) {
192			mq->full = false;
193			omap_mbox_enable_irq(mq->mbox, IRQ_RX);
194		}
195		spin_unlock_irq(&mq->lock);
196	}
197}
198
199/*
200 * Mailbox interrupt handler
201 */
202static void __mbox_tx_interrupt(struct omap_mbox *mbox)
203{
204	omap_mbox_disable_irq(mbox, IRQ_TX);
205	ack_mbox_irq(mbox, IRQ_TX);
206	tasklet_schedule(&mbox->txq->tasklet);
207}
208
209static void __mbox_rx_interrupt(struct omap_mbox *mbox)
210{
211	struct omap_mbox_queue *mq = mbox->rxq;
212	mbox_msg_t msg;
213	int len;
214
215	while (!mbox_fifo_empty(mbox)) {
216		if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg))) {
217			omap_mbox_disable_irq(mbox, IRQ_RX);
218			mq->full = true;
219			goto nomem;
220		}
221
222		msg = mbox_fifo_read(mbox);
223
224		len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
225		WARN_ON(len != sizeof(msg));
226
227		if (mbox->ops->type == OMAP_MBOX_TYPE1)
228			break;
229	}
230
231	/* no more messages in the fifo. clear IRQ source. */
232	ack_mbox_irq(mbox, IRQ_RX);
233nomem:
234	schedule_work(&mbox->rxq->work);
235}
236
237static irqreturn_t mbox_interrupt(int irq, void *p)
238{
239	struct omap_mbox *mbox = p;
240
241	if (is_mbox_irq(mbox, IRQ_TX))
242		__mbox_tx_interrupt(mbox);
243
244	if (is_mbox_irq(mbox, IRQ_RX))
245		__mbox_rx_interrupt(mbox);
246
247	return IRQ_HANDLED;
248}
249
250static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
251					void (*work) (struct work_struct *),
252					void (*tasklet)(unsigned long))
253{
254	struct omap_mbox_queue *mq;
255
256	mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
257	if (!mq)
258		return NULL;
259
260	spin_lock_init(&mq->lock);
261
262	if (kfifo_alloc(&mq->fifo, mbox_kfifo_size, GFP_KERNEL))
263		goto error;
264
265	if (work)
266		INIT_WORK(&mq->work, work);
267
268	if (tasklet)
269		tasklet_init(&mq->tasklet, tasklet, (unsigned long)mbox);
270	return mq;
271error:
272	kfree(mq);
273	return NULL;
274}
275
276static void mbox_queue_free(struct omap_mbox_queue *q)
277{
278	kfifo_free(&q->fifo);
279	kfree(q);
280}
281
282static int omap_mbox_startup(struct omap_mbox *mbox)
283{
284	int ret = 0;
285	struct omap_mbox_queue *mq;
286
287	mutex_lock(&mbox_configured_lock);
288	if (!mbox_configured++) {
289		if (likely(mbox->ops->startup)) {
290			ret = mbox->ops->startup(mbox);
291			if (unlikely(ret))
292				goto fail_startup;
293		} else
294			goto fail_startup;
295	}
296
297	if (!mbox->use_count++) {
298		mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
299		if (!mq) {
300			ret = -ENOMEM;
301			goto fail_alloc_txq;
302		}
303		mbox->txq = mq;
304
305		mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
306		if (!mq) {
307			ret = -ENOMEM;
308			goto fail_alloc_rxq;
309		}
310		mbox->rxq = mq;
311		mq->mbox = mbox;
312		ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
313							mbox->name, mbox);
314		if (unlikely(ret)) {
315			pr_err("failed to register mailbox interrupt:%d\n",
316									ret);
317			goto fail_request_irq;
318		}
319
320		omap_mbox_enable_irq(mbox, IRQ_RX);
321	}
322	mutex_unlock(&mbox_configured_lock);
323	return 0;
324
325fail_request_irq:
326	mbox_queue_free(mbox->rxq);
327fail_alloc_rxq:
328	mbox_queue_free(mbox->txq);
329fail_alloc_txq:
330	if (mbox->ops->shutdown)
331		mbox->ops->shutdown(mbox);
332	mbox->use_count--;
333fail_startup:
334	mbox_configured--;
335	mutex_unlock(&mbox_configured_lock);
336	return ret;
337}
338
339static void omap_mbox_fini(struct omap_mbox *mbox)
340{
341	mutex_lock(&mbox_configured_lock);
342
343	if (!--mbox->use_count) {
344		omap_mbox_disable_irq(mbox, IRQ_RX);
345		free_irq(mbox->irq, mbox);
346		tasklet_kill(&mbox->txq->tasklet);
347		flush_work(&mbox->rxq->work);
348		mbox_queue_free(mbox->txq);
349		mbox_queue_free(mbox->rxq);
350	}
351
352	if (likely(mbox->ops->shutdown)) {
353		if (!--mbox_configured)
354			mbox->ops->shutdown(mbox);
355	}
356
357	mutex_unlock(&mbox_configured_lock);
358}
359
360struct omap_mbox *omap_mbox_get(const char *name, struct notifier_block *nb)
361{
362	struct omap_mbox *_mbox, *mbox = NULL;
363	int i, ret;
364
365	if (!mboxes)
366		return ERR_PTR(-EINVAL);
367
368	for (i = 0; (_mbox = mboxes[i]); i++) {
369		if (!strcmp(_mbox->name, name)) {
370			mbox = _mbox;
371			break;
372		}
373	}
374
375	if (!mbox)
376		return ERR_PTR(-ENOENT);
377
378	if (nb)
379		blocking_notifier_chain_register(&mbox->notifier, nb);
380
381	ret = omap_mbox_startup(mbox);
382	if (ret) {
383		blocking_notifier_chain_unregister(&mbox->notifier, nb);
384		return ERR_PTR(-ENODEV);
385	}
386
387	return mbox;
388}
389EXPORT_SYMBOL(omap_mbox_get);
390
391void omap_mbox_put(struct omap_mbox *mbox, struct notifier_block *nb)
392{
393	blocking_notifier_chain_unregister(&mbox->notifier, nb);
394	omap_mbox_fini(mbox);
395}
396EXPORT_SYMBOL(omap_mbox_put);
397
398static struct class omap_mbox_class = { .name = "mbox", };
399
400int omap_mbox_register(struct device *parent, struct omap_mbox **list)
401{
402	int ret;
403	int i;
404
405	mboxes = list;
406	if (!mboxes)
407		return -EINVAL;
408
409	for (i = 0; mboxes[i]; i++) {
410		struct omap_mbox *mbox = mboxes[i];
411		mbox->dev = device_create(&omap_mbox_class,
412				parent, 0, mbox, "%s", mbox->name);
413		if (IS_ERR(mbox->dev)) {
414			ret = PTR_ERR(mbox->dev);
415			goto err_out;
416		}
417
418		BLOCKING_INIT_NOTIFIER_HEAD(&mbox->notifier);
419	}
420	return 0;
421
422err_out:
423	while (i--)
424		device_unregister(mboxes[i]->dev);
425	return ret;
426}
427EXPORT_SYMBOL(omap_mbox_register);
428
429int omap_mbox_unregister(void)
430{
431	int i;
432
433	if (!mboxes)
434		return -EINVAL;
435
436	for (i = 0; mboxes[i]; i++)
437		device_unregister(mboxes[i]->dev);
438	mboxes = NULL;
439	return 0;
440}
441EXPORT_SYMBOL(omap_mbox_unregister);
442
443static int __init omap_mbox_init(void)
444{
445	int err;
446
447	err = class_register(&omap_mbox_class);
448	if (err)
449		return err;
450
451	/* kfifo size sanity check: alignment and minimal size */
452	mbox_kfifo_size = ALIGN(mbox_kfifo_size, sizeof(mbox_msg_t));
453	mbox_kfifo_size = max_t(unsigned int, mbox_kfifo_size,
454							sizeof(mbox_msg_t));
455
456	return 0;
457}
458subsys_initcall(omap_mbox_init);
459
460static void __exit omap_mbox_exit(void)
461{
462	class_unregister(&omap_mbox_class);
463}
464module_exit(omap_mbox_exit);
465
466MODULE_LICENSE("GPL v2");
467MODULE_DESCRIPTION("omap mailbox: interrupt driven messaging");
468MODULE_AUTHOR("Toshihiro Kobayashi");
469MODULE_AUTHOR("Hiroshi DOYU");