aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/uwb/drp-avail.c
blob: 40a540a5a72ef00acb29151846ee95693a8a5b9d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
/*
 * Ultra Wide Band
 * DRP availability management
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Reinette Chatre <reinette.chatre@intel.com>
 * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 * Manage DRP Availability (the MAS available for DRP
 * reservations). Thus:
 *
 * - Handle DRP Availability Change notifications
 *
 * - Allow the reservation manager to indicate MAS reserved/released
 *   by local (owned by/targeted at the radio controller)
 *   reservations.
 *
 * - Based on the two sources above, generate a DRP Availability IE to
 *   be included in the beacon.
 *
 * See also the documentation for struct uwb_drp_avail.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/bitmap.h>
#include "uwb-internal.h"

/**
 * uwb_drp_avail_init - initialize an RC's MAS availability
 *
 * All MAS are available initially.  The RC will inform use which
 * slots are used for the BP (it may change in size).
 */
void uwb_drp_avail_init(struct uwb_rc *rc)
{
	bitmap_fill(rc->drp_avail.global, UWB_NUM_MAS);
	bitmap_fill(rc->drp_avail.local, UWB_NUM_MAS);
	bitmap_fill(rc->drp_avail.pending, UWB_NUM_MAS);
}

/*
 * Determine MAS available for new local reservations.
 *
 * avail = global & local & pending
 */
void uwb_drp_available(struct uwb_rc *rc, struct uwb_mas_bm *avail)
{
	bitmap_and(avail->bm, rc->drp_avail.global, rc->drp_avail.local, UWB_NUM_MAS);
	bitmap_and(avail->bm, avail->bm, rc->drp_avail.pending, UWB_NUM_MAS);
}

/**
 * uwb_drp_avail_reserve_pending - reserve MAS for a new reservation
 * @rc: the radio controller
 * @mas: the MAS to reserve
 *
 * Returns 0 on success, or -EBUSY if the MAS requested aren't available.
 */
int uwb_drp_avail_reserve_pending(struct uwb_rc *rc, struct uwb_mas_bm *mas)
{
	struct uwb_mas_bm avail;

	uwb_drp_available(rc, &avail);
	if (!bitmap_subset(mas->bm, avail.bm, UWB_NUM_MAS))
		return -EBUSY;

	bitmap_andnot(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
	return 0;
}

/**
 * uwb_drp_avail_reserve - reserve MAS for an established reservation
 * @rc: the radio controller
 * @mas: the MAS to reserve
 */
void uwb_drp_avail_reserve(struct uwb_rc *rc, struct uwb_mas_bm *mas)
{
	bitmap_or(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
	bitmap_andnot(rc->drp_avail.local, rc->drp_avail.local, mas->bm, UWB_NUM_MAS);
	rc->drp_avail.ie_valid = false;
}

/**
 * uwb_drp_avail_release - release MAS from a pending or established reservation
 * @rc: the radio controller
 * @mas: the MAS to release
 */
void uwb_drp_avail_release(struct uwb_rc *rc, struct uwb_mas_bm *mas)
{
	bitmap_or(rc->drp_avail.local, rc->drp_avail.local, mas->bm, UWB_NUM_MAS);
	bitmap_or(rc->drp_avail.pending, rc->drp_avail.pending, mas->bm, UWB_NUM_MAS);
	rc->drp_avail.ie_valid = false;
	uwb_rsv_handle_drp_avail_change(rc);
}

/**
 * uwb_drp_avail_ie_update - update the DRP Availability IE
 * @rc: the radio controller
 *
 * avail = global & local
 */
void uwb_drp_avail_ie_update(struct uwb_rc *rc)
{
	struct uwb_mas_bm avail;

	bitmap_and(avail.bm, rc->drp_avail.global, rc->drp_avail.local, UWB_NUM_MAS);

	rc->drp_avail.ie.hdr.element_id = UWB_IE_DRP_AVAILABILITY;
	rc->drp_avail.ie.hdr.length = UWB_NUM_MAS / 8;
	uwb_mas_bm_copy_le(rc->drp_avail.ie.bmp, &avail);
	rc->drp_avail.ie_valid = true;
}

/**
 * Create an unsigned long from a buffer containing a byte stream.
 *
 * @array: pointer to buffer
 * @itr:   index of buffer from where we start
 * @len:   the buffer's remaining size may not be exact multiple of
 *         sizeof(unsigned long), @len is the length of buffer that needs
 *         to be converted. This will be sizeof(unsigned long) or smaller
 *         (BUG if not). If it is smaller then we will pad the remaining
 *         space of the result with zeroes.
 */
static
unsigned long get_val(u8 *array, size_t itr, size_t len)
{
	unsigned long val = 0;
	size_t top = itr + len;

	BUG_ON(len > sizeof(val));

	while (itr < top) {
		val <<= 8;
		val |= array[top - 1];
		top--;
	}
	val <<= 8 * (sizeof(val) - len); /* padding */
	return val;
}

/**
 * Initialize bitmap from data buffer.
 *
 * The bitmap to be converted could come from a IE, for example a
 * DRP Availability IE.
 * From ECMA-368 1.0 [16.8.7]: "
 * octets: 1            1               N * (0 to 32)
 *         Element ID   Length (=N)     DRP Availability Bitmap
 *
 * The DRP Availability Bitmap field is up to 256 bits long, one
 * bit for each MAS in the superframe, where the least-significant
 * bit of the field corresponds to the first MAS in the superframe
 * and successive bits correspond to successive MASs."
 *
 * The DRP Availability bitmap is in octets from 0 to 32, so octet
 * 32 contains bits for MAS 1-8, etc. If the bitmap is smaller than 32
 * octets, the bits in octets not included at the end of the bitmap are
 * treated as zero. In this case (when the bitmap is smaller than 32
 * octets) the MAS represented range from MAS 1 to MAS (size of bitmap)
 * with the last octet still containing bits for MAS 1-8, etc.
 *
 * For example:
 * F00F0102 03040506 0708090A 0B0C0D0E 0F010203
 * ^^^^
 * ||||
 * ||||
 * |||\LSB of byte is MAS 9
 * ||\MSB of byte is MAS 16
 * |\LSB of first byte is MAS 1
 * \ MSB of byte is MAS 8
 *
 * An example of this encoding can be found in ECMA-368 Annex-D [Table D.11]
 *
 * The resulting bitmap will have the following mapping:
 *	bit position 0 == MAS 1
 *	bit position 1 == MAS 2
 *	...
 *	bit position (UWB_NUM_MAS - 1) == MAS UWB_NUM_MAS
 *
 * @bmp_itr:	pointer to bitmap (can be declared with DECLARE_BITMAP)
 * @buffer:	pointer to buffer containing bitmap data in big endian
 *              format (MSB first)
 * @buffer_size:number of bytes with which bitmap should be initialized
 */
static
void buffer_to_bmp(unsigned long *bmp_itr, void *_buffer,
		   size_t buffer_size)
{
	u8 *buffer = _buffer;
	size_t itr, len;
	unsigned long val;

	itr = 0;
	while (itr < buffer_size) {
		len = buffer_size - itr >= sizeof(val) ?
			sizeof(val) : buffer_size - itr;
		val = get_val(buffer, itr, len);
		bmp_itr[itr / sizeof(val)] = val;
		itr += sizeof(val);
	}
}


/**
 * Extract DRP Availability bitmap from the notification.
 *
 * The notification that comes in contains a bitmap of (UWB_NUM_MAS / 8) bytes
 * We convert that to our internal representation.
 */
static
int uwbd_evt_get_drp_avail(struct uwb_event *evt, unsigned long *bmp)
{
	struct device *dev = &evt->rc->uwb_dev.dev;
	struct uwb_rc_evt_drp_avail *drp_evt;
	int result = -EINVAL;

	/* Is there enough data to decode the event? */
	if (evt->notif.size < sizeof(*drp_evt)) {
		dev_err(dev, "DRP Availability Change: Not enough "
			"data to decode event [%zu bytes, %zu "
			"needed]\n", evt->notif.size, sizeof(*drp_evt));
		goto error;
	}
	drp_evt = container_of(evt->notif.rceb, struct uwb_rc_evt_drp_avail, rceb);
	buffer_to_bmp(bmp, drp_evt->bmp, UWB_NUM_MAS/8);
	result = 0;
error:
	return result;
}


/**
 * Process an incoming DRP Availability notification.
 *
 * @evt:	Event information (packs the actual event data, which
 *              radio controller it came to, etc).
 *
 * @returns:    0 on success (so uwbd() frees the event buffer), < 0
 *              on error.
 *
 * According to ECMA-368 1.0 [16.8.7], bits set to ONE indicate that
 * the MAS slot is available, bits set to ZERO indicate that the slot
 * is busy.
 *
 * So we clear available slots, we set used slots :)
 *
 * The notification only marks non-availability based on the BP and
 * received DRP IEs that are not for this radio controller.  A copy of
 * this bitmap is needed to generate the real availability (which
 * includes local and pending reservations).
 *
 * The DRP Availability IE that this radio controller emits will need
 * to be updated.
 */
int uwbd_evt_handle_rc_drp_avail(struct uwb_event *evt)
{
	int result;
	struct uwb_rc *rc = evt->rc;
	DECLARE_BITMAP(bmp, UWB_NUM_MAS);

	result = uwbd_evt_get_drp_avail(evt, bmp);
	if (result < 0)
		return result;

	mutex_lock(&rc->rsvs_mutex);
	bitmap_copy(rc->drp_avail.global, bmp, UWB_NUM_MAS);
	rc->drp_avail.ie_valid = false;
	uwb_rsv_handle_drp_avail_change(rc);
	mutex_unlock(&rc->rsvs_mutex);

	uwb_rsv_sched_update(rc);

	return 0;
}