uwb: add the UWB stack (reservation manager)

DRP and reservation management.

Signed-off-by: David Vrabel <david.vrabel@csr.com>

drivers/uwb/drp-avail.c

@@ -0,0 +1,288 @@
+/*
+ * 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
+ */
+static 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_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;
+	mutex_unlock(&rc->rsvs_mutex);
+
+	uwb_rsv_sched_update(rc);
+
+	return 0;
+}