uwb: add the UWB stack (radio controller interface)

Add the UWB radio controller interface (URCI) support.

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

1 files changed, 616 insertions, 0 deletions

diff --git a/drivers/uwb/neh.c b/drivers/uwb/neh.c
new file mode 100644
index 0000000..91b6148
--- /dev/null
+++ b/drivers/uwb/neh.c
@@ -0,0 +1,616 @@
+/*
+ * WUSB Wire Adapter: Radio Control Interface (WUSB[8])
+ * Notification and Event Handling
+ *
+ * Copyright (C) 2005-2006 Intel Corporation
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ *
+ * The RC interface of the Host Wire Adapter (USB dongle) or WHCI PCI
+ * card delivers a stream of notifications and events to the
+ * notification end event endpoint or area. This code takes care of
+ * getting a buffer with that data, breaking it up in separate
+ * notifications and events and then deliver those.
+ *
+ * Events are answers to commands and they carry a context ID that
+ * associates them to the command. Notifications are that,
+ * notifications, they come out of the blue and have a context ID of
+ * zero. Think of the context ID kind of like a handler. The
+ * uwb_rc_neh_* code deals with managing context IDs.
+ *
+ * This is why you require a handle to operate on a UWB host. When you
+ * open a handle a context ID is assigned to you.
+ *
+ * So, as it is done is:
+ *
+ * 1. Add an event handler [uwb_rc_neh_add()] (assigns a ctx id)
+ * 2. Issue command [rc->cmd(rc, ...)]
+ * 3. Arm the timeout timer [uwb_rc_neh_arm()]
+ * 4, Release the reference to the neh [uwb_rc_neh_put()]
+ * 5. Wait for the callback
+ * 6. Command result (RCEB) is passed to the callback
+ *
+ * If (2) fails, you should remove the handle [uwb_rc_neh_rm()]
+ * instead of arming the timer.
+ *
+ * Handles are for using in *serialized* code, single thread.
+ *
+ * When the notification/event comes, the IRQ handler/endpoint
+ * callback passes the data read to uwb_rc_neh_grok() which will break
+ * it up in a discrete series of events, look up who is listening for
+ * them and execute the pertinent callbacks.
+ *
+ * If the reader detects an error while reading the data stream, call
+ * uwb_rc_neh_error().
+ *
+ * CONSTRAINTS/ASSUMPTIONS:
+ *
+ * - Most notifications/events are small (less thank .5k), copying
+ *   around is ok.
+ *
+ * - Notifications/events are ALWAYS smaller than PAGE_SIZE
+ *
+ * - Notifications/events always come in a single piece (ie: a buffer
+ *   will always contain entire notifications/events).
+ *
+ * - we cannot know in advance how long each event is (because they
+ *   lack a length field in their header--smart move by the standards
+ *   body, btw). So we need a facility to get the event size given the
+ *   header. This is what the EST code does (notif/Event Size
+ *   Tables), check nest.c--as well, you can associate the size to
+ *   the handle [w/ neh->extra_size()].
+ *
+ * - Most notifications/events are fixed size; only a few are variable
+ *   size (NEST takes care of that).
+ *
+ * - Listeners of events expect them, so they usually provide a
+ *   buffer, as they know the size. Listeners to notifications don't,
+ *   so we allocate their buffers dynamically.
+ */
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/err.h>
+
+#include "uwb-internal.h"
+#define D_LOCAL 0
+#include <linux/uwb/debug.h>
+
+/*
+ * UWB Radio Controller Notification/Event Handle
+ *
+ * Represents an entity waiting for an event coming from the UWB Radio
+ * Controller with a given context id (context) and type (evt_type and
+ * evt). On reception of the notification/event, the callback (cb) is
+ * called with the event.
+ *
+ * If the timer expires before the event is received, the callback is
+ * called with -ETIMEDOUT as the event size.
+ */
+struct uwb_rc_neh {
+	struct kref kref;
+
+	struct uwb_rc *rc;
+	u8 evt_type;
+	__le16 evt;
+	u8 context;
+	uwb_rc_cmd_cb_f cb;
+	void *arg;
+
+	struct timer_list timer;
+	struct list_head list_node;
+};
+
+static void uwb_rc_neh_timer(unsigned long arg);
+
+static void uwb_rc_neh_release(struct kref *kref)
+{
+	struct uwb_rc_neh *neh = container_of(kref, struct uwb_rc_neh, kref);
+
+	kfree(neh);
+}
+
+static void uwb_rc_neh_get(struct uwb_rc_neh *neh)
+{
+	kref_get(&neh->kref);
+}
+
+/**
+ * uwb_rc_neh_put - release reference to a neh
+ * @neh: the neh
+ */
+void uwb_rc_neh_put(struct uwb_rc_neh *neh)
+{
+	kref_put(&neh->kref, uwb_rc_neh_release);
+}
+
+
+/**
+ * Assigns @neh a context id from @rc's pool
+ *
+ * @rc:	    UWB Radio Controller descriptor; @rc->neh_lock taken
+ * @neh:    Notification/Event Handle
+ * @returns 0 if context id was assigned ok; < 0 errno on error (if
+ *	    all the context IDs are taken).
+ *
+ * (assumes @wa is locked).
+ *
+ * NOTE: WUSB spec reserves context ids 0x00 for notifications and
+ *	 0xff is invalid, so they must not be used. Initialization
+ *	 fills up those two in the bitmap so they are not allocated.
+ *
+ * We spread the allocation around to reduce the posiblity of two
+ * consecutive opened @neh's getting the same context ID assigned (to
+ * avoid surprises with late events that timed out long time ago). So
+ * first we search from where @rc->ctx_roll is, if not found, we
+ * search from zero.
+ */
+static
+int __uwb_rc_ctx_get(struct uwb_rc *rc, struct uwb_rc_neh *neh)
+{
+	int result;
+	result = find_next_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX,
+				    rc->ctx_roll++);
+	if (result < UWB_RC_CTX_MAX)
+		goto found;
+	result = find_first_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX);
+	if (result < UWB_RC_CTX_MAX)
+		goto found;
+	return -ENFILE;
+found:
+	set_bit(result, rc->ctx_bm);
+	neh->context = result;
+	return 0;
+}
+
+
+/** Releases @neh's context ID back to @rc (@rc->neh_lock is locked). */
+static
+void __uwb_rc_ctx_put(struct uwb_rc *rc, struct uwb_rc_neh *neh)
+{
+	struct device *dev = &rc->uwb_dev.dev;
+	if (neh->context == 0)
+		return;
+	if (test_bit(neh->context, rc->ctx_bm) == 0) {
+		dev_err(dev, "context %u not set in bitmap\n",
+			neh->context);
+		WARN_ON(1);
+	}
+	clear_bit(neh->context, rc->ctx_bm);
+	neh->context = 0;
+}
+
+/**
+ * uwb_rc_neh_add - add a neh for a radio controller command
+ * @rc:             the radio controller
+ * @cmd:            the radio controller command
+ * @expected_type:  the type of the expected response event
+ * @expected_event: the expected event ID
+ * @cb:             callback for when the event is received
+ * @arg:            argument for the callback
+ *
+ * Creates a neh and adds it to the list of those waiting for an
+ * event.  A context ID will be assigned to the command.
+ */
+struct uwb_rc_neh *uwb_rc_neh_add(struct uwb_rc *rc, struct uwb_rccb *cmd,
+				  u8 expected_type, u16 expected_event,
+				  uwb_rc_cmd_cb_f cb, void *arg)
+{
+	int result;
+	unsigned long flags;
+	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_rc_neh *neh;
+
+	neh = kzalloc(sizeof(*neh), GFP_KERNEL);
+	if (neh == NULL) {
+		result = -ENOMEM;
+		goto error_kzalloc;
+	}
+
+	kref_init(&neh->kref);
+	INIT_LIST_HEAD(&neh->list_node);
+	init_timer(&neh->timer);
+	neh->timer.function = uwb_rc_neh_timer;
+	neh->timer.data     = (unsigned long)neh;
+
+	neh->rc = rc;
+	neh->evt_type = expected_type;
+	neh->evt = cpu_to_le16(expected_event);
+	neh->cb = cb;
+	neh->arg = arg;
+
+	spin_lock_irqsave(&rc->neh_lock, flags);
+	result = __uwb_rc_ctx_get(rc, neh);
+	if (result >= 0) {
+		cmd->bCommandContext = neh->context;
+		list_add_tail(&neh->list_node, &rc->neh_list);
+		uwb_rc_neh_get(neh);
+	}
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+	if (result < 0)
+		goto error_ctx_get;
+
+	return neh;
+
+error_ctx_get:
+	kfree(neh);
+error_kzalloc:
+	dev_err(dev, "cannot open handle to radio controller: %d\n", result);
+	return ERR_PTR(result);
+}
+
+static void __uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
+{
+	del_timer(&neh->timer);
+	__uwb_rc_ctx_put(rc, neh);
+	list_del(&neh->list_node);
+}
+
+/**
+ * uwb_rc_neh_rm - remove a neh.
+ * @rc:  the radio controller
+ * @neh: the neh to remove
+ *
+ * Remove an active neh immediately instead of waiting for the event
+ * (or a time out).
+ */
+void uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rc->neh_lock, flags);
+	__uwb_rc_neh_rm(rc, neh);
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+
+	uwb_rc_neh_put(neh);
+}
+
+/**
+ * uwb_rc_neh_arm - arm an event handler timeout timer
+ *
+ * @rc:     UWB Radio Controller
+ * @neh:    Notification/event handler for @rc
+ *
+ * The timer is only armed if the neh is active.
+ */
+void uwb_rc_neh_arm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rc->neh_lock, flags);
+	if (neh->context)
+		mod_timer(&neh->timer,
+			  jiffies + msecs_to_jiffies(UWB_RC_CMD_TIMEOUT_MS));
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+}
+
+static void uwb_rc_neh_cb(struct uwb_rc_neh *neh, struct uwb_rceb *rceb, size_t size)
+{
+	(*neh->cb)(neh->rc, neh->arg, rceb, size);
+	uwb_rc_neh_put(neh);
+}
+
+static bool uwb_rc_neh_match(struct uwb_rc_neh *neh, const struct uwb_rceb *rceb)
+{
+	return neh->evt_type == rceb->bEventType
+		&& neh->evt == rceb->wEvent
+		&& neh->context == rceb->bEventContext;
+}
+
+/**
+ * Find the handle waiting for a RC Radio Control Event
+ *
+ * @rc:         UWB Radio Controller
+ * @rceb:       Pointer to the RCEB buffer
+ * @event_size: Pointer to the size of the RCEB buffer. Might be
+ *              adjusted to take into account the @neh->extra_size
+ *              settings.
+ *
+ * If the listener has no buffer (NULL buffer), one is allocated for
+ * the right size (the amount of data received). @neh->ptr will point
+ * to the event payload, which always starts with a 'struct
+ * uwb_rceb'. kfree() it when done.
+ */
+static
+struct uwb_rc_neh *uwb_rc_neh_lookup(struct uwb_rc *rc,
+				     const struct uwb_rceb *rceb)
+{
+	struct uwb_rc_neh *neh = NULL, *h;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rc->neh_lock, flags);
+
+	list_for_each_entry(h, &rc->neh_list, list_node) {
+		if (uwb_rc_neh_match(h, rceb)) {
+			neh = h;
+			break;
+		}
+	}
+
+	if (neh)
+		__uwb_rc_neh_rm(rc, neh);
+
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+
+	return neh;
+}
+
+
+/**
+ * Process notifications coming from the radio control interface
+ *
+ * @rc:    UWB Radio Control Interface descriptor
+ * @neh:   Notification/Event Handler @neh->ptr points to
+ *         @uwb_evt->buffer.
+ *
+ * This function is called by the event/notif handling subsystem when
+ * notifications arrive (hwarc_probe() arms a notification/event handle
+ * that calls back this function for every received notification; this
+ * function then will rearm itself).
+ *
+ * Notification data buffers are dynamically allocated by the NEH
+ * handling code in neh.c [uwb_rc_neh_lookup()]. What is actually
+ * allocated is space to contain the notification data.
+ *
+ * Buffers are prefixed with a Radio Control Event Block (RCEB) as
+ * defined by the WUSB Wired-Adapter Radio Control interface. We
+ * just use it for the notification code.
+ *
+ * On each case statement we just transcode endianess of the different
+ * fields. We declare a pointer to a RCI definition of an event, and
+ * then to a UWB definition of the same event (which are the same,
+ * remember). Event if we use different pointers
+ */
+static
+void uwb_rc_notif(struct uwb_rc *rc, struct uwb_rceb *rceb, ssize_t size)
+{
+	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_event *uwb_evt;
+
+	if (size == -ESHUTDOWN)
+		return;
+	if (size < 0) {
+		dev_err(dev, "ignoring event with error code %zu\n",
+			size);
+		return;
+	}
+
+	uwb_evt = kzalloc(sizeof(*uwb_evt), GFP_ATOMIC);
+	if (unlikely(uwb_evt == NULL)) {
+		dev_err(dev, "no memory to queue event 0x%02x/%04x/%02x\n",
+			rceb->bEventType, le16_to_cpu(rceb->wEvent),
+			rceb->bEventContext);
+		return;
+	}
+	uwb_evt->rc = __uwb_rc_get(rc);	/* will be put by uwbd's uwbd_event_handle() */
+	uwb_evt->ts_jiffies = jiffies;
+	uwb_evt->type = UWB_EVT_TYPE_NOTIF;
+	uwb_evt->notif.size = size;
+	uwb_evt->notif.rceb = rceb;
+
+	switch (le16_to_cpu(rceb->wEvent)) {
+		/* Trap some vendor specific events
+		 *
+		 * FIXME: move this to handling in ptc-est, where we
+		 * register a NULL event handler for these two guys
+		 * using the Intel IDs.
+		 */
+	case 0x0103:
+		dev_info(dev, "FIXME: DEVICE ADD\n");
+		return;
+	case 0x0104:
+		dev_info(dev, "FIXME: DEVICE RM\n");
+		return;
+	default:
+		break;
+	}
+
+	uwbd_event_queue(uwb_evt);
+}
+
+static void uwb_rc_neh_grok_event(struct uwb_rc *rc, struct uwb_rceb *rceb, size_t size)
+{
+	struct device *dev = &rc->uwb_dev.dev;
+	struct uwb_rc_neh *neh;
+	struct uwb_rceb *notif;
+
+	if (rceb->bEventContext == 0) {
+		notif = kmalloc(size, GFP_ATOMIC);
+		if (notif) {
+			memcpy(notif, rceb, size);
+			uwb_rc_notif(rc, notif, size);
+		} else
+			dev_err(dev, "event 0x%02x/%04x/%02x (%zu bytes): no memory\n",
+				rceb->bEventType, le16_to_cpu(rceb->wEvent),
+				rceb->bEventContext, size);
+	} else {
+		neh = uwb_rc_neh_lookup(rc, rceb);
+		if (neh)
+			uwb_rc_neh_cb(neh, rceb, size);
+		else if (printk_ratelimit())
+			dev_warn(dev, "event 0x%02x/%04x/%02x (%zu bytes): nobody cared\n",
+				 rceb->bEventType, le16_to_cpu(rceb->wEvent),
+				 rceb->bEventContext, size);
+	}
+}
+
+/**
+ * Given a buffer with one or more UWB RC events/notifications, break
+ * them up and dispatch them.
+ *
+ * @rc:	      UWB Radio Controller
+ * @buf:      Buffer with the stream of notifications/events
+ * @buf_size: Amount of data in the buffer
+ *
+ * Note each notification/event starts always with a 'struct
+ * uwb_rceb', so the minimum size if 4 bytes.
+ *
+ * The device may pass us events formatted differently than expected.
+ * These are first filtered, potentially creating a new event in a new
+ * memory location. If a new event is created by the filter it is also
+ * freed here.
+ *
+ * For each notif/event, tries to guess the size looking at the EST
+ * tables, then looks for a neh that is waiting for that event and if
+ * found, copies the payload to the neh's buffer and calls it back. If
+ * not, the data is ignored.
+ *
+ * Note that if we can't find a size description in the EST tables, we
+ * still might find a size in the 'neh' handle in uwb_rc_neh_lookup().
+ *
+ * Assumptions:
+ *
+ *   @rc->neh_lock is NOT taken
+ *
+ * We keep track of various sizes here:
+ * size:      contains the size of the buffer that is processed for the
+ *            incoming event. this buffer may contain events that are not
+ *            formatted as WHCI.
+ * real_size: the actual space taken by this event in the buffer.
+ *            We need to keep track of the real size of an event to be able to
+ *            advance the buffer correctly.
+ * event_size: the size of the event as expected by the core layer
+ *            [OR] the size of the event after filtering. if the filtering
+ *            created a new event in a new memory location then this is
+ *            effectively the size of a new event buffer
+ */
+void uwb_rc_neh_grok(struct uwb_rc *rc, void *buf, size_t buf_size)
+{
+	struct device *dev = &rc->uwb_dev.dev;
+	void *itr;
+	struct uwb_rceb *rceb;
+	size_t size, real_size, event_size;
+	int needtofree;
+
+	d_fnstart(3, dev, "(rc %p buf %p %zu buf_size)\n", rc, buf, buf_size);
+	d_printf(2, dev, "groking event block: %zu bytes\n", buf_size);
+	itr = buf;
+	size = buf_size;
+	while (size > 0) {
+		if (size < sizeof(*rceb)) {
+			dev_err(dev, "not enough data in event buffer to "
+				"process incoming events (%zu left, minimum is "
+				"%zu)\n", size, sizeof(*rceb));
+			break;
+		}
+
+		rceb = itr;
+		if (rc->filter_event) {
+			needtofree = rc->filter_event(rc, &rceb, size,
+						      &real_size, &event_size);
+			if (needtofree < 0 && needtofree != -ENOANO) {
+				dev_err(dev, "BUG: Unable to filter event "
+					"(0x%02x/%04x/%02x) from "
+					"device. \n", rceb->bEventType,
+					le16_to_cpu(rceb->wEvent),
+					rceb->bEventContext);
+				break;
+			}
+		} else
+			needtofree = -ENOANO;
+		/* do real processing if there was no filtering or the
+		 * filtering didn't act */
+		if (needtofree == -ENOANO) {
+			ssize_t ret = uwb_est_find_size(rc, rceb, size);
+			if (ret < 0)
+				break;
+			if (ret > size) {
+				dev_err(dev, "BUG: hw sent incomplete event "
+					"0x%02x/%04x/%02x (%zd bytes), only got "
+					"%zu bytes. We don't handle that.\n",
+					rceb->bEventType, le16_to_cpu(rceb->wEvent),
+					rceb->bEventContext, ret, size);
+				break;
+			}
+			real_size = event_size = ret;
+		}
+		uwb_rc_neh_grok_event(rc, rceb, event_size);
+
+		if (needtofree == 1)
+			kfree(rceb);
+
+		itr += real_size;
+		size -= real_size;
+		d_printf(2, dev, "consumed %zd bytes, %zu left\n",
+			 event_size, size);
+	}
+	d_fnend(3, dev, "(rc %p buf %p %zu buf_size) = void\n", rc, buf, buf_size);
+}
+EXPORT_SYMBOL_GPL(uwb_rc_neh_grok);
+
+
+/**
+ * The entity that reads from the device notification/event channel has
+ * detected an error.
+ *
+ * @rc:    UWB Radio Controller
+ * @error: Errno error code
+ *
+ */
+void uwb_rc_neh_error(struct uwb_rc *rc, int error)
+{
+	struct uwb_rc_neh *neh, *next;
+	unsigned long flags;
+
+	BUG_ON(error >= 0);
+	spin_lock_irqsave(&rc->neh_lock, flags);
+	list_for_each_entry_safe(neh, next, &rc->neh_list, list_node) {
+		__uwb_rc_neh_rm(rc, neh);
+		uwb_rc_neh_cb(neh, NULL, error);
+	}
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+}
+EXPORT_SYMBOL_GPL(uwb_rc_neh_error);
+
+
+static void uwb_rc_neh_timer(unsigned long arg)
+{
+	struct uwb_rc_neh *neh = (struct uwb_rc_neh *)arg;
+	struct uwb_rc *rc = neh->rc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rc->neh_lock, flags);
+	__uwb_rc_neh_rm(rc, neh);
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+
+	uwb_rc_neh_cb(neh, NULL, -ETIMEDOUT);
+}
+
+/** Initializes the @rc's neh subsystem
+ */
+void uwb_rc_neh_create(struct uwb_rc *rc)
+{
+	spin_lock_init(&rc->neh_lock);
+	INIT_LIST_HEAD(&rc->neh_list);
+	set_bit(0, rc->ctx_bm);		/* 0 is reserved (see [WUSB] table 8-65) */
+	set_bit(0xff, rc->ctx_bm);	/* and 0xff is invalid */
+	rc->ctx_roll = 1;
+}
+
+
+/** Release's the @rc's neh subsystem */
+void uwb_rc_neh_destroy(struct uwb_rc *rc)
+{
+	unsigned long flags;
+	struct uwb_rc_neh *neh, *next;
+
+	spin_lock_irqsave(&rc->neh_lock, flags);
+	list_for_each_entry_safe(neh, next, &rc->neh_list, list_node) {
+		__uwb_rc_neh_rm(rc, neh);
+		uwb_rc_neh_put(neh);
+	}
+	spin_unlock_irqrestore(&rc->neh_lock, flags);
+}