1/*
2 * Copyright (c) 2005 Ammasso, Inc. All rights reserved.
3 * Copyright (c) 2005 Open Grid Computing, Inc. All rights reserved.
4 *
5 * This software is available to you under a choice of one of two
6 * licenses.  You may choose to be licensed under the terms of the GNU
7 * General Public License (GPL) Version 2, available from the file
8 * COPYING in the main directory of this source tree, or the
9 * OpenIB.org BSD license below:
10 *
11 *     Redistribution and use in source and binary forms, with or
12 *     without modification, are permitted provided that the following
13 *     conditions are met:
14 *
15 *      - Redistributions of source code must retain the above
16 *        copyright notice, this list of conditions and the following
17 *        disclaimer.
18 *
19 *      - Redistributions in binary form must reproduce the above
20 *        copyright notice, this list of conditions and the following
21 *        disclaimer in the documentation and/or other materials
22 *        provided with the distribution.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31 * SOFTWARE.
32 */
33#include <linux/slab.h>
34#include <linux/spinlock.h>
35
36#include "c2_vq.h"
37#include "c2_provider.h"
38
39/*
40 * Verbs Request Objects:
41 *
42 * VQ Request Objects are allocated by the kernel verbs handlers.
43 * They contain a wait object, a refcnt, an atomic bool indicating that the
44 * adapter has replied, and a copy of the verb reply work request.
45 * A pointer to the VQ Request Object is passed down in the context
46 * field of the work request message, and reflected back by the adapter
47 * in the verbs reply message.  The function handle_vq() in the interrupt
48 * path will use this pointer to:
49 * 	1) append a copy of the verbs reply message
50 * 	2) mark that the reply is ready
51 * 	3) wake up the kernel verbs handler blocked awaiting the reply.
52 *
53 *
54 * The kernel verbs handlers do a "get" to put a 2nd reference on the
55 * VQ Request object.  If the kernel verbs handler exits before the adapter
56 * can respond, this extra reference will keep the VQ Request object around
57 * until the adapter's reply can be processed.  The reason we need this is
58 * because a pointer to this object is stuffed into the context field of
59 * the verbs work request message, and reflected back in the reply message.
60 * It is used in the interrupt handler (handle_vq()) to wake up the appropriate
61 * kernel verb handler that is blocked awaiting the verb reply.
62 * So handle_vq() will do a "put" on the object when it's done accessing it.
63 * NOTE:  If we guarantee that the kernel verb handler will never bail before
64 *        getting the reply, then we don't need these refcnts.
65 *
66 *
67 * VQ Request objects are freed by the kernel verbs handlers only
68 * after the verb has been processed, or when the adapter fails and
69 * does not reply.
70 *
71 *
72 * Verbs Reply Buffers:
73 *
74 * VQ Reply bufs are local host memory copies of a
75 * outstanding Verb Request reply
76 * message.  The are always allocated by the kernel verbs handlers, and _may_ be
77 * freed by either the kernel verbs handler -or- the interrupt handler.  The
78 * kernel verbs handler _must_ free the repbuf, then free the vq request object
79 * in that order.
80 */
81
82int vq_init(struct c2_dev *c2dev)
83{
84	sprintf(c2dev->vq_cache_name, "c2-vq:dev%c",
85		(char) ('0' + c2dev->devnum));
86	c2dev->host_msg_cache =
87	    kmem_cache_create(c2dev->vq_cache_name, c2dev->rep_vq.msg_size, 0,
88			      SLAB_HWCACHE_ALIGN, NULL);
89	if (c2dev->host_msg_cache == NULL) {
90		return -ENOMEM;
91	}
92	return 0;
93}
94
95void vq_term(struct c2_dev *c2dev)
96{
97	kmem_cache_destroy(c2dev->host_msg_cache);
98}
99
100/* vq_req_alloc - allocate a VQ Request Object and initialize it.
101 * The refcnt is set to 1.
102 */
103struct c2_vq_req *vq_req_alloc(struct c2_dev *c2dev)
104{
105	struct c2_vq_req *r;
106
107	r = kmalloc(sizeof(struct c2_vq_req), GFP_KERNEL);
108	if (r) {
109		init_waitqueue_head(&r->wait_object);
110		r->reply_msg = 0;
111		r->event = 0;
112		r->cm_id = NULL;
113		r->qp = NULL;
114		atomic_set(&r->refcnt, 1);
115		atomic_set(&r->reply_ready, 0);
116	}
117	return r;
118}
119
120
121/* vq_req_free - free the VQ Request Object.  It is assumed the verbs handler
122 * has already free the VQ Reply Buffer if it existed.
123 */
124void vq_req_free(struct c2_dev *c2dev, struct c2_vq_req *r)
125{
126	r->reply_msg = 0;
127	if (atomic_dec_and_test(&r->refcnt)) {
128		kfree(r);
129	}
130}
131
132/* vq_req_get - reference a VQ Request Object.  Done
133 * only in the kernel verbs handlers.
134 */
135void vq_req_get(struct c2_dev *c2dev, struct c2_vq_req *r)
136{
137	atomic_inc(&r->refcnt);
138}
139
140
141/* vq_req_put - dereference and potentially free a VQ Request Object.
142 *
143 * This is only called by handle_vq() on the
144 * interrupt when it is done processing
145 * a verb reply message.  If the associated
146 * kernel verbs handler has already bailed,
147 * then this put will actually free the VQ
148 * Request object _and_ the VQ Reply Buffer
149 * if it exists.
150 */
151void vq_req_put(struct c2_dev *c2dev, struct c2_vq_req *r)
152{
153	if (atomic_dec_and_test(&r->refcnt)) {
154		if (r->reply_msg != 0)
155			vq_repbuf_free(c2dev,
156				       (void *) (unsigned long) r->reply_msg);
157		kfree(r);
158	}
159}
160
161
162/*
163 * vq_repbuf_alloc - allocate a VQ Reply Buffer.
164 */
165void *vq_repbuf_alloc(struct c2_dev *c2dev)
166{
167	return kmem_cache_alloc(c2dev->host_msg_cache, GFP_ATOMIC);
168}
169
170/*
171 * vq_send_wr - post a verbs request message to the Verbs Request Queue.
172 * If a message is not available in the MQ, then block until one is available.
173 * NOTE: handle_mq() on the interrupt context will wake up threads blocked here.
174 * When the adapter drains the Verbs Request Queue,
175 * it inserts MQ index 0 in to the
176 * adapter->host activity fifo and interrupts the host.
177 */
178int vq_send_wr(struct c2_dev *c2dev, union c2wr *wr)
179{
180	void *msg;
181	wait_queue_t __wait;
182
183	/*
184	 * grab adapter vq lock
185	 */
186	spin_lock(&c2dev->vqlock);
187
188	/*
189	 * allocate msg
190	 */
191	msg = c2_mq_alloc(&c2dev->req_vq);
192
193	/*
194	 * If we cannot get a msg, then we'll wait
195	 * When a messages are available, the int handler will wake_up()
196	 * any waiters.
197	 */
198	while (msg == NULL) {
199		pr_debug("%s:%d no available msg in VQ, waiting...\n",
200		       __func__, __LINE__);
201		init_waitqueue_entry(&__wait, current);
202		add_wait_queue(&c2dev->req_vq_wo, &__wait);
203		spin_unlock(&c2dev->vqlock);
204		for (;;) {
205			set_current_state(TASK_INTERRUPTIBLE);
206			if (!c2_mq_full(&c2dev->req_vq)) {
207				break;
208			}
209			if (!signal_pending(current)) {
210				schedule_timeout(1 * HZ);	/* 1 second... */
211				continue;
212			}
213			set_current_state(TASK_RUNNING);
214			remove_wait_queue(&c2dev->req_vq_wo, &__wait);
215			return -EINTR;
216		}
217		set_current_state(TASK_RUNNING);
218		remove_wait_queue(&c2dev->req_vq_wo, &__wait);
219		spin_lock(&c2dev->vqlock);
220		msg = c2_mq_alloc(&c2dev->req_vq);
221	}
222
223	/*
224	 * copy wr into adapter msg
225	 */
226	memcpy(msg, wr, c2dev->req_vq.msg_size);
227
228	/*
229	 * post msg
230	 */
231	c2_mq_produce(&c2dev->req_vq);
232
233	/*
234	 * release adapter vq lock
235	 */
236	spin_unlock(&c2dev->vqlock);
237	return 0;
238}
239
240
241/*
242 * vq_wait_for_reply - block until the adapter posts a Verb Reply Message.
243 */
244int vq_wait_for_reply(struct c2_dev *c2dev, struct c2_vq_req *req)
245{
246	if (!wait_event_timeout(req->wait_object,
247				atomic_read(&req->reply_ready),
248				60*HZ))
249		return -ETIMEDOUT;
250
251	return 0;
252}
253
254/*
255 * vq_repbuf_free - Free a Verbs Reply Buffer.
256 */
257void vq_repbuf_free(struct c2_dev *c2dev, void *reply)
258{
259	kmem_cache_free(c2dev->host_msg_cache, reply);
260}
261