rt2x00: Queue handling overhaul

This introduces a big queue handling overhaul, this also
renames "ring" to "queues".

Move queue handling into rt2x00queue.c and the matching header,
use Kerneldoc to improve rt2x00 library documentation.

Access to the queues is now protected under a spinlock, this
to prevent race conditions which could corrupt the indexing
system of the queue.

Each queue entry allocates x bytes for driver/device specific data,
this cleans up the queue structure significantly and improves
code readability.

rt2500usb no longer needs 2 entries in the beacon queue to correctly
send out the guardian byte. This is now handled in the entry specific
structure.

rt61 and rt73 now use the correct descriptor size for beacon frames,
since this data is written into the registers not the entire TXD
descriptor was used but instead of a subset of it named TXINFO.

Finally this also fixes numerous other bugs related to incorrect
beacon handling or beacon related code.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 435 insertions, 0 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.h b/drivers/net/wireless/rt2x00/rt2x00queue.h
new file mode 100644
index 000000000000..507116c6c9fe
--- /dev/null
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.h
@@ -0,0 +1,435 @@
+/*
+	Copyright (C) 2004 - 2008 rt2x00 SourceForge Project
+	<http://rt2x00.serialmonkey.com>
+
+	This program is free software; you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation; either version 2 of the License, or
+	(at your option) any later version.
+
+	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.,
+	59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*
+	Module: rt2x00
+	Abstract: rt2x00 queue datastructures and routines
+ */
+
+#ifndef RT2X00QUEUE_H
+#define RT2X00QUEUE_H
+
+#include <linux/prefetch.h>
+
+/**
+ * DOC: Entrie frame size
+ *
+ * Ralink PCI devices demand the Frame size to be a multiple of 128 bytes,
+ * for USB devices this restriction does not apply, but the value of
+ * 2432 makes sense since it is big enough to contain the maximum fragment
+ * size according to the ieee802.11 specs.
+ */
+#define DATA_FRAME_SIZE	2432
+#define MGMT_FRAME_SIZE	256
+
+/**
+ * DOC: Number of entries per queue
+ *
+ * After research it was concluded that 12 entries in a RX and TX
+ * queue would be sufficient. Although this is almost one third of
+ * the amount the legacy driver allocated, the queues aren't getting
+ * filled to the maximum even when working with the maximum rate.
+ *
+ * FIXME: For virtual interfaces we need a different number
+ * of beacons, since more interfaces require more beacons.
+ */
+#define RX_ENTRIES	12
+#define TX_ENTRIES	12
+#define BEACON_ENTRIES	1
+#define ATIM_ENTRIES	1
+
+/**
+ * enum data_queue_qid: Queue identification
+ */
+enum data_queue_qid {
+	QID_AC_BE = 0,
+	QID_AC_BK = 1,
+	QID_AC_VI = 2,
+	QID_AC_VO = 3,
+	QID_HCCA = 4,
+	QID_MGMT = 13,
+	QID_RX = 14,
+	QID_OTHER = 15,
+};
+
+/**
+ * struct skb_frame_desc: Descriptor information for the skb buffer
+ *
+ * This structure is placed over the skb->cb array, this means that
+ * this structure should not exceed the size of that array (48 bytes).
+ *
+ * @flags: Frame flags.
+ * @frame_type: Frame type, see &enum rt2x00_dump_type.
+ * @data: Pointer to data part of frame (Start of ieee80211 header).
+ * @desc: Pointer to descriptor part of the frame.
+ *	Note that this pointer could point to something outside
+ *	of the scope of the skb->data pointer.
+ * @data_len: Length of the frame data.
+ * @desc_len: Length of the frame descriptor.
+
+ * @entry: The entry to which this sk buffer belongs.
+ */
+struct skb_frame_desc {
+	unsigned int flags;
+
+	unsigned int frame_type;
+
+	void *data;
+	void *desc;
+
+	unsigned int data_len;
+	unsigned int desc_len;
+
+	struct queue_entry *entry;
+};
+
+static inline struct skb_frame_desc* get_skb_frame_desc(struct sk_buff *skb)
+{
+	BUILD_BUG_ON(sizeof(struct skb_frame_desc) > sizeof(skb->cb));
+	return (struct skb_frame_desc *)&skb->cb[0];
+}
+
+/**
+ * struct rxdone_entry_desc: RX Entry descriptor
+ *
+ * Summary of information that has been read from the RX frame descriptor.
+ *
+ * @signal: Signal of the received frame.
+ * @rssi: RSSI of the received frame.
+ * @ofdm: Was frame send with an OFDM rate.
+ * @size: Data size of the received frame.
+ * @flags: MAC80211 receive flags (See &enum mac80211_rx_flags).
+ * @my_bss: Does this frame originate from device's BSS.
+ */
+struct rxdone_entry_desc {
+	int signal;
+	int rssi;
+	int ofdm;
+	int size;
+	int flags;
+	int my_bss;
+};
+
+/**
+ * struct txdone_entry_desc: TX done entry descriptor
+ *
+ * Summary of information that has been read from the TX frame descriptor
+ * after the device is done with transmission.
+ *
+ * @control: Control structure which was used to transmit the frame.
+ * @status: TX status (See &enum tx_status).
+ * @retry: Retry count.
+ */
+struct txdone_entry_desc {
+	struct ieee80211_tx_control *control;
+	int status;
+	int retry;
+};
+
+/**
+ * enum txentry_desc_flags: Status flags for TX entry descriptor
+ *
+ * @ENTRY_TXD_RTS_FRAME: This frame is a RTS frame.
+ * @ENTRY_TXD_OFDM_RATE: This frame is send out with an OFDM rate.
+ * @ENTRY_TXD_MORE_FRAG: This frame is followed by another fragment.
+ * @ENTRY_TXD_REQ_TIMESTAMP: Require timestamp to be inserted.
+ * @ENTRY_TXD_BURST: This frame belongs to the same burst event.
+ * @ENTRY_TXD_ACK: An ACK is required for this frame.
+ */
+enum txentry_desc_flags {
+	ENTRY_TXD_RTS_FRAME,
+	ENTRY_TXD_OFDM_RATE,
+	ENTRY_TXD_MORE_FRAG,
+	ENTRY_TXD_REQ_TIMESTAMP,
+	ENTRY_TXD_BURST,
+	ENTRY_TXD_ACK,
+};
+
+/**
+ * struct txentry_desc: TX Entry descriptor
+ *
+ * Summary of information for the frame descriptor before sending a TX frame.
+ *
+ * @flags: Descriptor flags (See &enum queue_entry_flags).
+ * @queue: Queue identification (See &enum data_queue_qid).
+ * @length_high: PLCP length high word.
+ * @length_low: PLCP length low word.
+ * @signal: PLCP signal.
+ * @service: PLCP service.
+ * @aifs: AIFS value.
+ * @ifs: IFS value.
+ * @cw_min: cwmin value.
+ * @cw_max: cwmax value.
+ */
+struct txentry_desc {
+	unsigned long flags;
+
+	enum data_queue_qid queue;
+
+	u16 length_high;
+	u16 length_low;
+	u16 signal;
+	u16 service;
+
+	int aifs;
+	int ifs;
+	int cw_min;
+	int cw_max;
+};
+
+/**
+ * enum queue_entry_flags: Status flags for queue entry
+ *
+ * @ENTRY_BCN_ASSIGNED: This entry has been assigned to an interface.
+ *	As long as this bit is set, this entry may only be touched
+ *	through the interface structure.
+ * @ENTRY_OWNER_DEVICE_DATA: This entry is owned by the device for data
+ *	transfer (either TX or RX depending on the queue). The entry should
+ *	only be touched after the device has signaled it is done with it.
+ * @ENTRY_OWNER_DEVICE_CRYPTO: This entry is owned by the device for data
+ *	encryption or decryption. The entry should only be touched after
+ *	the device has signaled it is done with it.
+ */
+
+enum queue_entry_flags {
+	ENTRY_BCN_ASSIGNED,
+	ENTRY_OWNER_DEVICE_DATA,
+	ENTRY_OWNER_DEVICE_CRYPTO,
+};
+
+/**
+ * struct queue_entry: Entry inside the &struct data_queue
+ *
+ * @flags: Entry flags, see &enum queue_entry_flags.
+ * @queue: The data queue (&struct data_queue) to which this entry belongs.
+ * @skb: The buffer which is currently being transmitted (for TX queue),
+ *	or used to directly recieve data in (for RX queue).
+ * @entry_idx: The entry index number.
+ * @priv_data: Private data belonging to this queue entry. The pointer
+ *	points to data specific to a particular driver and queue type.
+ */
+struct queue_entry {
+	unsigned long flags;
+
+	struct data_queue *queue;
+
+	struct sk_buff *skb;
+
+	unsigned int entry_idx;
+
+	void *priv_data;
+};
+
+/**
+ * enum queue_index: Queue index type
+ *
+ * @Q_INDEX: Index pointer to the current entry in the queue, if this entry is
+ *	owned by the hardware then the queue is considered to be full.
+ * @Q_INDEX_DONE: Index pointer to the next entry which will be completed by
+ *	the hardware and for which we need to run the txdone handler. If this
+ *	entry is not owned by the hardware the queue is considered to be empty.
+ * @Q_INDEX_CRYPTO: Index pointer to the next entry which encryption/decription
+ *	will be completed by the hardware next.
+ * @Q_INDEX_MAX: Keep last, used in &struct data_queue to determine the size
+ *	of the index array.
+ */
+enum queue_index {
+	Q_INDEX,
+	Q_INDEX_DONE,
+	Q_INDEX_CRYPTO,
+	Q_INDEX_MAX,
+};
+
+/**
+ * struct data_queue: Data queue
+ *
+ * @rt2x00dev: Pointer to main &struct rt2x00dev where this queue belongs to.
+ * @entries: Base address of the &struct queue_entry which are
+ *	part of this queue.
+ * @qid: The queue identification, see &enum data_queue_qid.
+ * @lock: Spinlock to protect index handling. Whenever @index, @index_done or
+ *	@index_crypt needs to be changed this lock should be grabbed to prevent
+ *	index corruption due to concurrency.
+ * @count: Number of frames handled in the queue.
+ * @limit: Maximum number of entries in the queue.
+ * @length: Number of frames in queue.
+ * @index: Index pointers to entry positions in the queue,
+ *	use &enum queue_index to get a specific index field.
+ * @aifs: The aifs value for outgoing frames (field ignored in RX queue).
+ * @cw_min: The cw min value for outgoing frames (field ignored in RX queue).
+ * @cw_max: The cw max value for outgoing frames (field ignored in RX queue).
+ * @data_size: Maximum data size for the frames in this queue.
+ * @desc_size: Hardware descriptor size for the data in this queue.
+ */
+struct data_queue {
+	struct rt2x00_dev *rt2x00dev;
+	struct queue_entry *entries;
+
+	enum data_queue_qid qid;
+
+	spinlock_t lock;
+	unsigned int count;
+	unsigned short limit;
+	unsigned short length;
+	unsigned short index[Q_INDEX_MAX];
+
+	unsigned short aifs;
+	unsigned short cw_min;
+	unsigned short cw_max;
+
+	unsigned short data_size;
+	unsigned short desc_size;
+};
+
+/**
+ * struct data_queue_desc: Data queue description
+ *
+ * The information in this structure is used by drivers
+ * to inform rt2x00lib about the creation of the data queue.
+ *
+ * @entry_num: Maximum number of entries for a queue.
+ * @data_size: Maximum data size for the frames in this queue.
+ * @desc_size: Hardware descriptor size for the data in this queue.
+ * @priv_size: Size of per-queue_entry private data.
+ */
+struct data_queue_desc {
+	unsigned short entry_num;
+	unsigned short data_size;
+	unsigned short desc_size;
+	unsigned short priv_size;
+};
+
+/**
+ * queue_end - Return pointer to the last queue (HELPER MACRO).
+ * @__dev: Pointer to &struct rt2x00_dev
+ *
+ * Using the base rx pointer and the maximum number of available queues,
+ * this macro will return the address of 1 position beyond  the end of the
+ * queues array.
+ */
+#define queue_end(__dev) \
+	&(__dev)->rx[(__dev)->data_queues]
+
+/**
+ * tx_queue_end - Return pointer to the last TX queue (HELPER MACRO).
+ * @__dev: Pointer to &struct rt2x00_dev
+ *
+ * Using the base tx pointer and the maximum number of available TX
+ * queues, this macro will return the address of 1 position beyond
+ * the end of the TX queue array.
+ */
+#define tx_queue_end(__dev) \
+	&(__dev)->tx[(__dev)->hw->queues]
+
+/**
+ * queue_loop - Loop through the queues within a specific range (HELPER MACRO).
+ * @__entry: Pointer where the current queue entry will be stored in.
+ * @__start: Start queue pointer.
+ * @__end: End queue pointer.
+ *
+ * This macro will loop through all queues between &__start and &__end.
+ */
+#define queue_loop(__entry, __start, __end)			\
+	for ((__entry) = (__start);				\
+	     prefetch(&(__entry)[1]), (__entry) != (__end);	\
+	     (__entry) = &(__entry)[1])
+
+/**
+ * queue_for_each - Loop through all queues
+ * @__dev: Pointer to &struct rt2x00_dev
+ * @__entry: Pointer where the current queue entry will be stored in.
+ *
+ * This macro will loop through all available queues.
+ */
+#define queue_for_each(__dev, __entry) \
+	queue_loop(__entry, (__dev)->rx, queue_end(__dev))
+
+/**
+ * tx_queue_for_each - Loop through the TX queues
+ * @__dev: Pointer to &struct rt2x00_dev
+ * @__entry: Pointer where the current queue entry will be stored in.
+ *
+ * This macro will loop through all TX related queues excluding
+ * the Beacon and Atim queues.
+ */
+#define tx_queue_for_each(__dev, __entry) \
+	queue_loop(__entry, (__dev)->tx, tx_queue_end(__dev))
+
+/**
+ * txall_queue_for_each - Loop through all TX related queues
+ * @__dev: Pointer to &struct rt2x00_dev
+ * @__entry: Pointer where the current queue entry will be stored in.
+ *
+ * This macro will loop through all TX related queues including
+ * the Beacon and Atim queues.
+ */
+#define txall_queue_for_each(__dev, __entry) \
+	queue_loop(__entry, (__dev)->tx, queue_end(__dev))
+
+/**
+ * rt2x00queue_empty - Check if the queue is empty.
+ * @queue: Queue to check if empty.
+ */
+static inline int rt2x00queue_empty(struct data_queue *queue)
+{
+	return queue->length == 0;
+}
+
+/**
+ * rt2x00queue_full - Check if the queue is full.
+ * @queue: Queue to check if full.
+ */
+static inline int rt2x00queue_full(struct data_queue *queue)
+{
+	return queue->length == queue->limit;
+}
+
+/**
+ * rt2x00queue_free - Check the number of available entries in queue.
+ * @queue: Queue to check.
+ */
+static inline int rt2x00queue_available(struct data_queue *queue)
+{
+	return queue->limit - queue->length;
+}
+
+/**
+ * rt2x00_desc_read - Read a word from the hardware descriptor.
+ * @desc: Base descriptor address
+ * @word: Word index from where the descriptor should be read.
+ * @value: Address where the descriptor value should be written into.
+ */
+static inline void rt2x00_desc_read(__le32 *desc, const u8 word, u32 *value)
+{
+	*value = le32_to_cpu(desc[word]);
+}
+
+/**
+ * rt2x00_desc_write - wrote a word to the hardware descriptor.
+ * @desc: Base descriptor address
+ * @word: Word index from where the descriptor should be written.
+ * @value: Value that should be written into the descriptor.
+ */
+static inline void rt2x00_desc_write(__le32 *desc, const u8 word, u32 value)
+{
+	desc[word] = cpu_to_le32(value);
+}
+
+#endif /* RT2X00QUEUE_H */