1 /*
2  * Ultra Wide Band
3  * DRP availability management
4  *
5  * Copyright (C) 2005-2006 Intel Corporation
6  * Reinette Chatre <reinette.chatre@intel.com>
7  * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
8  *
9  * This program is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU General Public License version
11  * 2 as published by the Free Software Foundation.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
20  *
21  *
22  * Manage DRP Availability (the MAS available for DRP
23  * reservations). Thus:
24  *
25  * - Handle DRP Availability Change notifications
26  *
27  * - Allow the reservation manager to indicate MAS reserved/released
28  *   by local (owned by/targeted at the radio controller)
29  *   reservations.
30  *
31  * - Based on the two sources above, generate a DRP Availability IE to
32  *   be included in the beacon.
33  *
34  * See also the documentation for struct uwb_drp_avail.
35  */
36 
37 #include <linux/errno.h>
38 #include <linux/module.h>
39 #include <linux/device.h>
40 #include <linux/bitmap.h>
41 #include "uwb-internal.h"
42 
43 /**
44  * uwb_drp_avail_init - initialize an RC's MAS availability
45  *
46  * All MAS are available initially.  The RC will inform use which
47  * slots are used for the BP (it may change in size).
48  */
uwb_drp_avail_init(struct uwb_rc * rc)49 void uwb_drp_avail_init(struct uwb_rc *rc)
50 {
51 	bitmap_fill(rc->drp_avail.global, UWB_NUM_MAS);
52 	bitmap_fill(rc->drp_avail.local, UWB_NUM_MAS);
53 	bitmap_fill(rc->drp_avail.pending, UWB_NUM_MAS);
54 }
55 
56 /*
57  * Determine MAS available for new local reservations.
58  *
59  * avail = global & local & pending
60  */
uwb_drp_available(struct uwb_rc * rc,struct uwb_mas_bm * avail)61 void uwb_drp_available(struct uwb_rc *rc, struct uwb_mas_bm *avail)
62 {
63 	bitmap_and(avail->bm, rc->drp_avail.global, rc->drp_avail.local, UWB_NUM_MAS);
64 	bitmap_and(avail->bm, avail->bm, rc->drp_avail.pending, UWB_NUM_MAS);
65 }
66 
67 /**
68  * uwb_drp_avail_reserve_pending - reserve MAS for a new reservation
69  * @rc: the radio controller
70  * @mas: the MAS to reserve
71  *
72  * Returns 0 on success, or -EBUSY if the MAS requested aren't available.
73  */
uwb_drp_avail_reserve_pending(struct uwb_rc * rc,struct uwb_mas_bm * mas)74 int uwb_drp_avail_reserve_pending(struct uwb_rc *rc, struct uwb_mas_bm *mas)
75 {
76 	struct uwb_mas_bm avail;
77 
78 	uwb_drp_available(rc, &avail);
79 	if (!bitmap_subset(mas->bm, avail.bm, UWB_NUM_MAS))
80 		return -EBUSY;
81 
82 	bitmap_andnot(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
83 	return 0;
84 }
85 
86 /**
87  * uwb_drp_avail_reserve - reserve MAS for an established reservation
88  * @rc: the radio controller
89  * @mas: the MAS to reserve
90  */
uwb_drp_avail_reserve(struct uwb_rc * rc,struct uwb_mas_bm * mas)91 void uwb_drp_avail_reserve(struct uwb_rc *rc, struct uwb_mas_bm *mas)
92 {
93 	bitmap_or(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
94 	bitmap_andnot(rc->drp_avail.local, rc->drp_avail.local, mas->bm, UWB_NUM_MAS);
95 	rc->drp_avail.ie_valid = false;
96 }
97 
98 /**
99  * uwb_drp_avail_release - release MAS from a pending or established reservation
100  * @rc: the radio controller
101  * @mas: the MAS to release
102  */
uwb_drp_avail_release(struct uwb_rc * rc,struct uwb_mas_bm * mas)103 void uwb_drp_avail_release(struct uwb_rc *rc, struct uwb_mas_bm *mas)
104 {
105 	bitmap_or(rc->drp_avail.local, rc->drp_avail.local, mas->bm, UWB_NUM_MAS);
106 	bitmap_or(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
107 	rc->drp_avail.ie_valid = false;
108 	uwb_rsv_handle_drp_avail_change(rc);
109 }
110 
111 /**
112  * uwb_drp_avail_ie_update - update the DRP Availability IE
113  * @rc: the radio controller
114  *
115  * avail = global & local
116  */
uwb_drp_avail_ie_update(struct uwb_rc * rc)117 void uwb_drp_avail_ie_update(struct uwb_rc *rc)
118 {
119 	struct uwb_mas_bm avail;
120 
121 	bitmap_and(avail.bm, rc->drp_avail.global, rc->drp_avail.local, UWB_NUM_MAS);
122 
123 	rc->drp_avail.ie.hdr.element_id = UWB_IE_DRP_AVAILABILITY;
124 	rc->drp_avail.ie.hdr.length = UWB_NUM_MAS / 8;
125 	uwb_mas_bm_copy_le(rc->drp_avail.ie.bmp, &avail);
126 	rc->drp_avail.ie_valid = true;
127 }
128 
129 /**
130  * Create an unsigned long from a buffer containing a byte stream.
131  *
132  * @array: pointer to buffer
133  * @itr:   index of buffer from where we start
134  * @len:   the buffer's remaining size may not be exact multiple of
135  *         sizeof(unsigned long), @len is the length of buffer that needs
136  *         to be converted. This will be sizeof(unsigned long) or smaller
137  *         (BUG if not). If it is smaller then we will pad the remaining
138  *         space of the result with zeroes.
139  */
140 static
get_val(u8 * array,size_t itr,size_t len)141 unsigned long get_val(u8 *array, size_t itr, size_t len)
142 {
143 	unsigned long val = 0;
144 	size_t top = itr + len;
145 
146 	BUG_ON(len > sizeof(val));
147 
148 	while (itr < top) {
149 		val <<= 8;
150 		val |= array[top - 1];
151 		top--;
152 	}
153 	val <<= 8 * (sizeof(val) - len); /* padding */
154 	return val;
155 }
156 
157 /**
158  * Initialize bitmap from data buffer.
159  *
160  * The bitmap to be converted could come from a IE, for example a
161  * DRP Availability IE.
162  * From ECMA-368 1.0 [16.8.7]: "
163  * octets: 1            1               N * (0 to 32)
164  *         Element ID   Length (=N)     DRP Availability Bitmap
165  *
166  * The DRP Availability Bitmap field is up to 256 bits long, one
167  * bit for each MAS in the superframe, where the least-significant
168  * bit of the field corresponds to the first MAS in the superframe
169  * and successive bits correspond to successive MASs."
170  *
171  * The DRP Availability bitmap is in octets from 0 to 32, so octet
172  * 32 contains bits for MAS 1-8, etc. If the bitmap is smaller than 32
173  * octets, the bits in octets not included at the end of the bitmap are
174  * treated as zero. In this case (when the bitmap is smaller than 32
175  * octets) the MAS represented range from MAS 1 to MAS (size of bitmap)
176  * with the last octet still containing bits for MAS 1-8, etc.
177  *
178  * For example:
179  * F00F0102 03040506 0708090A 0B0C0D0E 0F010203
180  * ^^^^
181  * ||||
182  * ||||
183  * |||\LSB of byte is MAS 9
184  * ||\MSB of byte is MAS 16
185  * |\LSB of first byte is MAS 1
186  * \ MSB of byte is MAS 8
187  *
188  * An example of this encoding can be found in ECMA-368 Annex-D [Table D.11]
189  *
190  * The resulting bitmap will have the following mapping:
191  *	bit position 0 == MAS 1
192  *	bit position 1 == MAS 2
193  *	...
194  *	bit position (UWB_NUM_MAS - 1) == MAS UWB_NUM_MAS
195  *
196  * @bmp_itr:	pointer to bitmap (can be declared with DECLARE_BITMAP)
197  * @buffer:	pointer to buffer containing bitmap data in big endian
198  *              format (MSB first)
199  * @buffer_size:number of bytes with which bitmap should be initialized
200  */
201 static
buffer_to_bmp(unsigned long * bmp_itr,void * _buffer,size_t buffer_size)202 void buffer_to_bmp(unsigned long *bmp_itr, void *_buffer,
203 		   size_t buffer_size)
204 {
205 	u8 *buffer = _buffer;
206 	size_t itr, len;
207 	unsigned long val;
208 
209 	itr = 0;
210 	while (itr < buffer_size) {
211 		len = buffer_size - itr >= sizeof(val) ?
212 			sizeof(val) : buffer_size - itr;
213 		val = get_val(buffer, itr, len);
214 		bmp_itr[itr / sizeof(val)] = val;
215 		itr += sizeof(val);
216 	}
217 }
218 
219 
220 /**
221  * Extract DRP Availability bitmap from the notification.
222  *
223  * The notification that comes in contains a bitmap of (UWB_NUM_MAS / 8) bytes
224  * We convert that to our internal representation.
225  */
226 static
uwbd_evt_get_drp_avail(struct uwb_event * evt,unsigned long * bmp)227 int uwbd_evt_get_drp_avail(struct uwb_event *evt, unsigned long *bmp)
228 {
229 	struct device *dev = &evt->rc->uwb_dev.dev;
230 	struct uwb_rc_evt_drp_avail *drp_evt;
231 	int result = -EINVAL;
232 
233 	/* Is there enough data to decode the event? */
234 	if (evt->notif.size < sizeof(*drp_evt)) {
235 		dev_err(dev, "DRP Availability Change: Not enough "
236 			"data to decode event [%zu bytes, %zu "
237 			"needed]\n", evt->notif.size, sizeof(*drp_evt));
238 		goto error;
239 	}
240 	drp_evt = container_of(evt->notif.rceb, struct uwb_rc_evt_drp_avail, rceb);
241 	buffer_to_bmp(bmp, drp_evt->bmp, UWB_NUM_MAS/8);
242 	result = 0;
243 error:
244 	return result;
245 }
246 
247 
248 /**
249  * Process an incoming DRP Availability notification.
250  *
251  * @evt:	Event information (packs the actual event data, which
252  *              radio controller it came to, etc).
253  *
254  * @returns:    0 on success (so uwbd() frees the event buffer), < 0
255  *              on error.
256  *
257  * According to ECMA-368 1.0 [16.8.7], bits set to ONE indicate that
258  * the MAS slot is available, bits set to ZERO indicate that the slot
259  * is busy.
260  *
261  * So we clear available slots, we set used slots :)
262  *
263  * The notification only marks non-availability based on the BP and
264  * received DRP IEs that are not for this radio controller.  A copy of
265  * this bitmap is needed to generate the real availability (which
266  * includes local and pending reservations).
267  *
268  * The DRP Availability IE that this radio controller emits will need
269  * to be updated.
270  */
uwbd_evt_handle_rc_drp_avail(struct uwb_event * evt)271 int uwbd_evt_handle_rc_drp_avail(struct uwb_event *evt)
272 {
273 	int result;
274 	struct uwb_rc *rc = evt->rc;
275 	DECLARE_BITMAP(bmp, UWB_NUM_MAS);
276 
277 	result = uwbd_evt_get_drp_avail(evt, bmp);
278 	if (result < 0)
279 		return result;
280 
281 	mutex_lock(&rc->rsvs_mutex);
282 	bitmap_copy(rc->drp_avail.global, bmp, UWB_NUM_MAS);
283 	rc->drp_avail.ie_valid = false;
284 	uwb_rsv_handle_drp_avail_change(rc);
285 	mutex_unlock(&rc->rsvs_mutex);
286 
287 	uwb_rsv_sched_update(rc);
288 
289 	return 0;
290 }
291