iwlwifi: add comments to iwl*-base.c

Add comments to iwlXXXX-base.c

Signed-off-by: Cahill, Ben M <ben.m.cahill@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 177 insertions, 38 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index ba5146ffdf4..71e9b7c52d5 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -63,13 +63,13 @@ static int iwl3945_tx_queue_update_write_ptr(struct iwl3945_priv *priv,
  ******************************************************************************/
 
 /* module parameters */
-static int iwl3945_param_disable_hw_scan;
-static int iwl3945_param_debug;
-static int iwl3945_param_disable;  /* def: enable radio */
+static int iwl3945_param_disable_hw_scan; /* def: 0 = use 3945's h/w scan */
+static int iwl3945_param_debug;    /* def: 0 = minimal debug log messages */
+static int iwl3945_param_disable;  /* def: 0 = enable radio */
 static int iwl3945_param_antenna;  /* def: 0 = both antennas (use diversity) */
-int iwl3945_param_hwcrypto;        /* def: using software encryption */
-static int iwl3945_param_qos_enable = 1;
-int iwl3945_param_queues_num = IWL_MAX_NUM_QUEUES;
+int iwl3945_param_hwcrypto;        /* def: 0 = use software encryption */
+static int iwl3945_param_qos_enable = 1; /* def: 1 = use quality of service */
+int iwl3945_param_queues_num = IWL_MAX_NUM_QUEUES; /* def: 8 Tx queues */
 
 /*
  * module name, copyright, version, etc.
@@ -184,17 +184,24 @@ static void iwl3945_print_hex_dump(int level, void *p, u32 len)
  *
  * Theory of operation
  *
- * A queue is a circular buffers with 'Read' and 'Write' pointers.
- * 2 empty entries always kept in the buffer to protect from overflow.
+ * A Tx or Rx queue resides in host DRAM, and is comprised of a circular buffer
+ * of buffer descriptors, each of which points to one or more data buffers for
+ * the device to read from or fill.  Driver and device exchange status of each
+ * queue via "read" and "write" pointers.  Driver keeps minimum of 2 empty
+ * entries in each circular buffer, to protect against confusing empty and full
+ * queue states.
+ *
+ * The device reads or writes the data in the queues via the device's several
+ * DMA/FIFO channels.  Each queue is mapped to a single DMA channel.
  *
  * For Tx queue, there are low mark and high mark limits. If, after queuing
  * the packet for Tx, free space become < low mark, Tx queue stopped. When
  * reclaiming packets (on 'tx done IRQ), if free space become > high mark,
  * Tx queue resumed.
  *
- * The IWL operates with six queues, one receive queue in the device's
- * sram, one transmit queue for sending commands to the device firmware,
- * and four transmit queues for data.
+ * The 3945 operates with six queues:  One receive queue, one transmit queue
+ * (#4) for sending commands to the device firmware, and four transmit queues
+ * (#0-3) for data tx via EDCA.  An additional 2 HCCA queues are unused.
  ***************************************************/
 
 static int iwl3945_queue_space(const struct iwl3945_queue *q)
@@ -213,13 +220,21 @@ static int iwl3945_queue_space(const struct iwl3945_queue *q)
 	return s;
 }
 
-/* XXX: n_bd must be power-of-two size */
+/**
+ * iwl3945_queue_inc_wrap - increment queue index, wrap back to beginning
+ * @index -- current index
+ * @n_bd -- total number of entries in queue (must be power of 2)
+ */
 static inline int iwl3945_queue_inc_wrap(int index, int n_bd)
 {
 	return ++index & (n_bd - 1);
 }
 
-/* XXX: n_bd must be power-of-two size */
+/**
+ * iwl3945_queue_dec_wrap - increment queue index, wrap back to end
+ * @index -- current index
+ * @n_bd -- total number of entries in queue (must be power of 2)
+ */
 static inline int iwl3945_queue_dec_wrap(int index, int n_bd)
 {
 	return --index & (n_bd - 1);
@@ -234,12 +249,17 @@ static inline int x2_queue_used(const struct iwl3945_queue *q, int i)
 
 static inline u8 get_cmd_index(struct iwl3945_queue *q, u32 index, int is_huge)
 {
+	/* This is for scan command, the big buffer at end of command array */
 	if (is_huge)
-		return q->n_window;
+		return q->n_window;	/* must be power of 2 */
 
+	/* Otherwise, use normal size buffers */
 	return index & (q->n_window - 1);
 }
 
+/**
+ * iwl3945_queue_init - Initialize queue's high/low-water and read/write indexes
+ */
 static int iwl3945_queue_init(struct iwl3945_priv *priv, struct iwl3945_queue *q,
 			  int count, int slots_num, u32 id)
 {
@@ -268,11 +288,16 @@ static int iwl3945_queue_init(struct iwl3945_priv *priv, struct iwl3945_queue *q
 	return 0;
 }
 
+/**
+ * iwl3945_tx_queue_alloc - Alloc driver data and TFD CB for one Tx/cmd queue
+ */
 static int iwl3945_tx_queue_alloc(struct iwl3945_priv *priv,
 			      struct iwl3945_tx_queue *txq, u32 id)
 {
 	struct pci_dev *dev = priv->pci_dev;
 
+	/* Driver private data, only for Tx (not command) queues,
+	 * not shared with device. */
 	if (id != IWL_CMD_QUEUE_NUM) {
 		txq->txb = kmalloc(sizeof(txq->txb[0]) *
 				   TFD_QUEUE_SIZE_MAX, GFP_KERNEL);
@@ -284,6 +309,8 @@ static int iwl3945_tx_queue_alloc(struct iwl3945_priv *priv,
 	} else
 		txq->txb = NULL;
 
+	/* Circular buffer of transmit frame descriptors (TFDs),
+	 * shared with device */
 	txq->bd = pci_alloc_consistent(dev,
 			sizeof(txq->bd[0]) * TFD_QUEUE_SIZE_MAX,
 			&txq->q.dma_addr);
@@ -306,6 +333,9 @@ static int iwl3945_tx_queue_alloc(struct iwl3945_priv *priv,
 	return -ENOMEM;
 }
 
+/**
+ * iwl3945_tx_queue_init - Allocate and initialize one tx/cmd queue
+ */
 int iwl3945_tx_queue_init(struct iwl3945_priv *priv,
 		      struct iwl3945_tx_queue *txq, int slots_num, u32 txq_id)
 {
@@ -313,9 +343,14 @@ int iwl3945_tx_queue_init(struct iwl3945_priv *priv,
 	int len;
 	int rc = 0;
 
-	/* allocate command space + one big command for scan since scan
-	 * command is very huge the system will not have two scan at the
-	 * same time */
+	/*
+	 * Alloc buffer array for commands (Tx or other types of commands).
+	 * For the command queue (#4), allocate command space + one big
+	 * command for scan, since scan command is very huge; the system will
+	 * not have two scans at the same time, so only one is needed.
+	 * For data Tx queues (all other queues), no super-size command
+	 * space is needed.
+	 */
 	len = sizeof(struct iwl3945_cmd) * slots_num;
 	if (txq_id == IWL_CMD_QUEUE_NUM)
 		len +=  IWL_MAX_SCAN_SIZE;
@@ -323,6 +358,7 @@ int iwl3945_tx_queue_init(struct iwl3945_priv *priv,
 	if (!txq->cmd)
 		return -ENOMEM;
 
+	/* Alloc driver data array and TFD circular buffer */
 	rc = iwl3945_tx_queue_alloc(priv, txq, txq_id);
 	if (rc) {
 		pci_free_consistent(dev, len, txq->cmd, txq->dma_addr_cmd);
@@ -334,8 +370,11 @@ int iwl3945_tx_queue_init(struct iwl3945_priv *priv,
 	/* TFD_QUEUE_SIZE_MAX must be power-of-two size, otherwise
 	 * iwl3945_queue_inc_wrap and iwl3945_queue_dec_wrap are broken. */
 	BUILD_BUG_ON(TFD_QUEUE_SIZE_MAX & (TFD_QUEUE_SIZE_MAX - 1));
+
+	/* Initialize queue high/low-water, head/tail indexes */
 	iwl3945_queue_init(priv, &txq->q, TFD_QUEUE_SIZE_MAX, slots_num, txq_id);
 
+	/* Tell device where to find queue, enable DMA channel. */
 	iwl3945_hw_tx_queue_init(priv, txq);
 
 	return 0;
@@ -346,8 +385,8 @@ int iwl3945_tx_queue_init(struct iwl3945_priv *priv,
  * @txq: Transmit queue to deallocate.
  *
  * Empty queue by removing and destroying all BD's.
- * Free all buffers.  txq itself is not freed.
- *
+ * Free all buffers.
+ * 0-fill, but do not free "txq" descriptor structure.
  */
 void iwl3945_tx_queue_free(struct iwl3945_priv *priv, struct iwl3945_tx_queue *txq)
 {
@@ -367,19 +406,21 @@ void iwl3945_tx_queue_free(struct iwl3945_priv *priv, struct iwl3945_tx_queue *t
 	if (q->id == IWL_CMD_QUEUE_NUM)
 		len += IWL_MAX_SCAN_SIZE;
 
+	/* De-alloc array of command/tx buffers */
 	pci_free_consistent(dev, len, txq->cmd, txq->dma_addr_cmd);
 
-	/* free buffers belonging to queue itself */
+	/* De-alloc circular buffer of TFDs */
 	if (txq->q.n_bd)
 		pci_free_consistent(dev, sizeof(struct iwl3945_tfd_frame) *
 				    txq->q.n_bd, txq->bd, txq->q.dma_addr);
 
+	/* De-alloc array of per-TFD driver data */
 	if (txq->txb) {
 		kfree(txq->txb);
 		txq->txb = NULL;
 	}
 
-	/* 0 fill whole structure */
+	/* 0-fill queue descriptor structure */
 	memset(txq, 0, sizeof(*txq));
 }
 
@@ -392,6 +433,11 @@ const u8 iwl3945_broadcast_addr[ETH_ALEN] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
 
 /**************************************************************/
 #if 0 /* temporary disable till we add real remove station */
+/**
+ * iwl3945_remove_station - Remove driver's knowledge of station.
+ *
+ * NOTE:  This does not remove station from device's station table.
+ */
 static u8 iwl3945_remove_station(struct iwl3945_priv *priv, const u8 *addr, int is_ap)
 {
 	int index = IWL_INVALID_STATION;
@@ -428,6 +474,12 @@ out:
 	return 0;
 }
 #endif
+
+/**
+ * iwl3945_clear_stations_table - Clear the driver's station table
+ *
+ * NOTE:  This does not clear or otherwise alter the device's station table.
+ */
 static void iwl3945_clear_stations_table(struct iwl3945_priv *priv)
 {
 	unsigned long flags;
@@ -440,7 +492,9 @@ static void iwl3945_clear_stations_table(struct iwl3945_priv *priv)
 	spin_unlock_irqrestore(&priv->sta_lock, flags);
 }
 
-
+/**
+ * iwl3945_add_station - Add station to station tables in driver and device
+ */
 u8 iwl3945_add_station(struct iwl3945_priv *priv, const u8 *addr, int is_ap, u8 flags)
 {
 	int i;
@@ -486,6 +540,7 @@ u8 iwl3945_add_station(struct iwl3945_priv *priv, const u8 *addr, int is_ap, u8
 	station->used = 1;
 	priv->num_stations++;
 
+	/* Set up the REPLY_ADD_STA command to send to device */
 	memset(&station->sta, 0, sizeof(struct iwl3945_addsta_cmd));
 	memcpy(station->sta.sta.addr, addr, ETH_ALEN);
 	station->sta.mode = 0;
@@ -504,6 +559,8 @@ u8 iwl3945_add_station(struct iwl3945_priv *priv, const u8 *addr, int is_ap, u8
 			le16_to_cpu(station->sta.rate_n_flags);
 
 	spin_unlock_irqrestore(&priv->sta_lock, flags_spin);
+
+	/* Add station to device's station table */
 	iwl3945_send_add_station(priv, &station->sta, flags);
 	return index;
 
@@ -673,6 +730,8 @@ static int iwl3945_enqueue_hcmd(struct iwl3945_priv *priv, struct iwl3945_host_c
 		     fix_size, q->write_ptr, idx, IWL_CMD_QUEUE_NUM);
 
 	txq->need_update = 1;
+
+	/* Increment and update queue's write index */
 	q->write_ptr = iwl3945_queue_inc_wrap(q->write_ptr, q->n_bd);
 	ret = iwl3945_tx_queue_update_write_ptr(priv, txq);
 
@@ -1511,7 +1570,7 @@ static void get_eeprom_mac(struct iwl3945_priv *priv, u8 *mac)
 /**
  * iwl3945_eeprom_init - read EEPROM contents
  *
- * Load the EEPROM from adapter into priv->eeprom
+ * Load the EEPROM contents from adapter into priv->eeprom
  *
  * NOTE:  This routine uses the non-debug IO access functions.
  */
@@ -1536,6 +1595,7 @@ int iwl3945_eeprom_init(struct iwl3945_priv *priv)
 		return -ENOENT;
 	}
 
+	/* Make sure driver (instead of uCode) is allowed to read EEPROM */
 	rc = iwl3945_eeprom_acquire_semaphore(priv);
 	if (rc < 0) {
 		IWL_ERROR("Failed to acquire EEPROM semaphore.\n");
@@ -2631,21 +2691,23 @@ static void iwl3945_build_tx_cmd_basic(struct iwl3945_priv *priv,
 	cmd->cmd.tx.next_frame_len = 0;
 }
 
+/**
+ * iwl3945_get_sta_id - Find station's index within station table
+ */
 static int iwl3945_get_sta_id(struct iwl3945_priv *priv, struct ieee80211_hdr *hdr)
 {
 	int sta_id;
 	u16 fc = le16_to_cpu(hdr->frame_control);
 
-	/* If this frame is broadcast or not data then use the broadcast
-	 * station id */
+	/* If this frame is broadcast or management, use broadcast station id */
 	if (((fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_DATA) ||
 	    is_multicast_ether_addr(hdr->addr1))
 		return priv->hw_setting.bcast_sta_id;
 
 	switch (priv->iw_mode) {
 
-	/* If this frame is part of a BSS network (we're a station), then
-	 * we use the AP's station id */
+	/* If we are a client station in a BSS network, use the special
+	 * AP station entry (that's the only station we communicate with) */
 	case IEEE80211_IF_TYPE_STA:
 		return IWL_AP_ID;
 
@@ -2656,11 +2718,12 @@ static int iwl3945_get_sta_id(struct iwl3945_priv *priv, struct ieee80211_hdr *h
 			return sta_id;
 		return priv->hw_setting.bcast_sta_id;
 
-	/* If this frame is part of a IBSS network, then we use the
-	 * target specific station id */
+	/* If this frame is going out to an IBSS network, find the station,
+	 * or create a new station table entry */
 	case IEEE80211_IF_TYPE_IBSS: {
 		DECLARE_MAC_BUF(mac);
 
+		/* Create new station table entry */
 		sta_id = iwl3945_hw_find_station(priv, hdr->addr1);
 		if (sta_id != IWL_INVALID_STATION)
 			return sta_id;
@@ -2746,6 +2809,8 @@ static int iwl3945_tx_skb(struct iwl3945_priv *priv,
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	hdr_len = ieee80211_get_hdrlen(fc);
+
+	/* Find (or create) index into station table for destination station */
 	sta_id = iwl3945_get_sta_id(priv, hdr);
 	if (sta_id == IWL_INVALID_STATION) {
 		DECLARE_MAC_BUF(mac);
@@ -2767,30 +2832,52 @@ static int iwl3945_tx_skb(struct iwl3945_priv *priv,
 				__constant_cpu_to_le16(IEEE80211_SCTL_FRAG));
 		seq_number += 0x10;
 	}
+
+	/* Descriptor for chosen Tx queue */
 	txq = &priv->txq[txq_id];
 	q = &txq->q;
 
 	spin_lock_irqsave(&priv->lock, flags);
 
+	/* Set up first empty TFD within this queue's circular TFD buffer */
 	tfd = &txq->bd[q->write_ptr];
 	memset(tfd, 0, sizeof(*tfd));
 	control_flags = (u32 *) tfd;
 	idx = get_cmd_index(q, q->write_ptr, 0);
 
+	/* Set up driver data for this TFD */
 	memset(&(txq->txb[q->write_ptr]), 0, sizeof(struct iwl3945_tx_info));
 	txq->txb[q->write_ptr].skb[0] = skb;
 	memcpy(&(txq->txb[q->write_ptr].status.control),
 	       ctl, sizeof(struct ieee80211_tx_control));
+
+	/* Init first empty entry in queue's array of Tx/cmd buffers */
 	out_cmd = &txq->cmd[idx];
 	memset(&out_cmd->hdr, 0, sizeof(out_cmd->hdr));
 	memset(&out_cmd->cmd.tx, 0, sizeof(out_cmd->cmd.tx));
+
+	/*
+	 * Set up the Tx-command (not MAC!) header.
+	 * Store the chosen Tx queue and TFD index within the sequence field;
+	 * after Tx, uCode's Tx response will return this value so driver can
+	 * locate the frame within the tx queue and do post-tx processing.
+	 */
 	out_cmd->hdr.cmd = REPLY_TX;
 	out_cmd->hdr.sequence = cpu_to_le16((u16)(QUEUE_TO_SEQ(txq_id) |
 				INDEX_TO_SEQ(q->write_ptr)));
-	/* copy frags header */
+
+	/* Copy MAC header from skb into command buffer */
 	memcpy(out_cmd->cmd.tx.hdr, hdr, hdr_len);
 
-	/* hdr = (struct ieee80211_hdr *)out_cmd->cmd.tx.hdr; */
+	/*
+	 * Use the first empty entry in this queue's command buffer array
+	 * to contain the Tx command and MAC header concatenated together
+	 * (payload data will be in another buffer).
+	 * Size of this varies, due to varying MAC header length.
+	 * If end is not dword aligned, we'll have 2 extra bytes at the end
+	 * of the MAC header (device reads on dword boundaries).
+	 * We'll tell device about this padding later.
+	 */
 	len = priv->hw_setting.tx_cmd_len +
 		sizeof(struct iwl3945_cmd_header) + hdr_len;
 
@@ -2802,15 +2889,20 @@ static int iwl3945_tx_skb(struct iwl3945_priv *priv,
 	else
 		len_org = 0;
 
+	/* Physical address of this Tx command's header (not MAC header!),
+	 * within command buffer array. */
 	txcmd_phys = txq->dma_addr_cmd + sizeof(struct iwl3945_cmd) * idx +
 		     offsetof(struct iwl3945_cmd, hdr);
 
+	/* Add buffer containing Tx command and MAC(!) header to TFD's
+	 * first entry */
 	iwl3945_hw_txq_attach_buf_to_tfd(priv, tfd, txcmd_phys, len);
 
 	if (!(ctl->flags & IEEE80211_TXCTL_DO_NOT_ENCRYPT))
 		iwl3945_build_tx_cmd_hwcrypto(priv, ctl, out_cmd, skb, 0);
 
-	/* 802.11 null functions have no payload... */
+	/* Set up TFD's 2nd entry to point directly to remainder of skb,
+	 * if any (802.11 null frames have no payload). */
 	len = skb->len - hdr_len;
 	if (len) {
 		phys_addr = pci_map_single(priv->pci_dev, skb->data + hdr_len,
@@ -2818,13 +2910,16 @@ static int iwl3945_tx_skb(struct iwl3945_priv *priv,
 		iwl3945_hw_txq_attach_buf_to_tfd(priv, tfd, phys_addr, len);
 	}
 
-	/* If there is no payload, then only one TFD is used */
 	if (!len)
+		/* If there is no payload, then we use only one Tx buffer */
 		*control_flags = TFD_CTL_COUNT_SET(1);
 	else
+		/* Else use 2 buffers.
+		 * Tell 3945 about any padding after MAC header */
 		*control_flags = TFD_CTL_COUNT_SET(2) |
 			TFD_CTL_PAD_SET(U32_PAD(len));
 
+	/* Total # bytes to be transmitted */
 	len = (u16)skb->len;
 	out_cmd->cmd.tx.len = cpu_to_le16(len);
 
@@ -2854,6 +2949,7 @@ static int iwl3945_tx_skb(struct iwl3945_priv *priv,
 	iwl3945_print_hex_dump(IWL_DL_TX, (u8 *)out_cmd->cmd.tx.hdr,
 			   ieee80211_get_hdrlen(fc));
 
+	/* Tell device the write index *just past* this latest filled TFD */
 	q->write_ptr = iwl3945_queue_inc_wrap(q->write_ptr, q->n_bd);
 	rc = iwl3945_tx_queue_update_write_ptr(priv, txq);
 	spin_unlock_irqrestore(&priv->lock, flags);
@@ -3329,11 +3425,11 @@ static void iwl3945_txstatus_to_ieee(struct iwl3945_priv *priv,
 }
 
 /**
- * iwl3945_tx_queue_reclaim - Reclaim Tx queue entries no more used by NIC.
+ * iwl3945_tx_queue_reclaim - Reclaim Tx queue entries already Tx'd
  *
- * When FW advances 'R' index, all entries between old and
- * new 'R' index need to be reclaimed. As result, some free space
- * forms. If there is enough free space (> low mark), wake Tx queue.
+ * When FW advances 'R' index, all entries between old and new 'R' index
+ * need to be reclaimed. As result, some free space forms. If there is
+ * enough free space (> low mark), wake the stack that feeds us.
  */
 static int iwl3945_tx_queue_reclaim(struct iwl3945_priv *priv, int txq_id, int index)
 {
@@ -3382,6 +3478,9 @@ static int iwl3945_is_tx_success(u32 status)
  * Generic RX handler implementations
  *
  ******************************************************************************/
+/**
+ * iwl3945_rx_reply_tx - Handle Tx response
+ */
 static void iwl3945_rx_reply_tx(struct iwl3945_priv *priv,
 			    struct iwl3945_rx_mem_buffer *rxb)
 {
@@ -3917,6 +4016,7 @@ int iwl3945_rx_queue_update_write_ptr(struct iwl3945_priv *priv, struct iwl3945_
 	if (q->need_update == 0)
 		goto exit_unlock;
 
+	/* If power-saving is in use, make sure device is awake */
 	if (test_bit(STATUS_POWER_PMI, &priv->status)) {
 		reg = iwl3945_read32(priv, CSR_UCODE_DRV_GP1);
 
@@ -3930,10 +4030,14 @@ int iwl3945_rx_queue_update_write_ptr(struct iwl3945_priv *priv, struct iwl3945_
 		if (rc)
 			goto exit_unlock;
 
+		/* Device expects a multiple of 8 */
 		iwl3945_write_direct32(priv, FH_RSCSR_CHNL0_WPTR,
 				     q->write & ~0x7);
 		iwl3945_release_nic_access(priv);
+
+	/* Else device is assumed to be awake */
 	} else
+		/* Device expects a multiple of 8 */
 		iwl3945_write32(priv, FH_RSCSR_CHNL0_WPTR, q->write & ~0x7);
 
 
@@ -3975,9 +4079,12 @@ static int iwl3945_rx_queue_restock(struct iwl3945_priv *priv)
 	spin_lock_irqsave(&rxq->lock, flags);
 	write = rxq->write & ~0x7;
 	while ((iwl3945_rx_queue_space(rxq) > 0) && (rxq->free_count)) {
+		/* Get next free Rx buffer, remove from free list */
 		element = rxq->rx_free.next;
 		rxb = list_entry(element, struct iwl3945_rx_mem_buffer, list);
 		list_del(element);
+
+		/* Point to Rx buffer via next RBD in circular buffer */
 		rxq->bd[rxq->write] = iwl3945_dma_addr2rbd_ptr(priv, rxb->dma_addr);
 		rxq->queue[rxq->write] = rxb;
 		rxq->write = (rxq->write + 1) & RX_QUEUE_MASK;
@@ -3990,7 +4097,8 @@ static int iwl3945_rx_queue_restock(struct iwl3945_priv *priv)
 		queue_work(priv->workqueue, &priv->rx_replenish);
 
 
-	/* If we've added more space for the firmware to place data, tell it */
+	/* If we've added more space for the firmware to place data, tell it.
+	 * Increment device's write pointer in multiples of 8. */
 	if ((write != (rxq->write & ~0x7))
 	    || (abs(rxq->write - rxq->read) > 7)) {
 		spin_lock_irqsave(&rxq->lock, flags);
@@ -4023,6 +4131,8 @@ void iwl3945_rx_replenish(void *data)
 	while (!list_empty(&rxq->rx_used)) {
 		element = rxq->rx_used.next;
 		rxb = list_entry(element, struct iwl3945_rx_mem_buffer, list);
+
+		/* Alloc a new receive buffer */
 		rxb->skb =
 		    alloc_skb(IWL_RX_BUF_SIZE, __GFP_NOWARN | GFP_ATOMIC);
 		if (!rxb->skb) {
@@ -4036,6 +4146,8 @@ void iwl3945_rx_replenish(void *data)
 		}
 		priv->alloc_rxb_skb++;
 		list_del(element);
+
+		/* Get physical address of RB/SKB */
 		rxb->dma_addr =
 		    pci_map_single(priv->pci_dev, rxb->skb->data,
 				   IWL_RX_BUF_SIZE, PCI_DMA_FROMDEVICE);
@@ -4080,12 +4192,16 @@ int iwl3945_rx_queue_alloc(struct iwl3945_priv *priv)
 	spin_lock_init(&rxq->lock);
 	INIT_LIST_HEAD(&rxq->rx_free);
 	INIT_LIST_HEAD(&rxq->rx_used);
+
+	/* Alloc the circular buffer of Read Buffer Descriptors (RBDs) */
 	rxq->bd = pci_alloc_consistent(dev, 4 * RX_QUEUE_SIZE, &rxq->dma_addr);
 	if (!rxq->bd)
 		return -ENOMEM;
+
 	/* Fill the rx_used queue with _all_ of the Rx buffers */
 	for (i = 0; i < RX_FREE_BUFFERS + RX_QUEUE_SIZE; i++)
 		list_add_tail(&rxq->pool[i].list, &rxq->rx_used);
+
 	/* Set us so that we have processed and used all buffers, but have
 	 * not restocked the Rx queue with fresh buffers */
 	rxq->read = rxq->write = 0;
@@ -4217,6 +4333,8 @@ static void iwl3945_rx_handle(struct iwl3945_priv *priv)
 	int reclaim;
 	unsigned long flags;
 
+	/* uCode's read index (stored in shared DRAM) indicates the last Rx
+	 * buffer that the driver may process (last buffer filled by ucode). */
 	r = iwl3945_hw_get_rx_read(priv);
 	i = rxq->read;
 
@@ -4297,6 +4415,9 @@ static void iwl3945_rx_handle(struct iwl3945_priv *priv)
 	iwl3945_rx_queue_restock(priv);
 }
 
+/**
+ * iwl3945_tx_queue_update_write_ptr - Send new write index to hardware
+ */
 static int iwl3945_tx_queue_update_write_ptr(struct iwl3945_priv *priv,
 				  struct iwl3945_tx_queue *txq)
 {
@@ -4926,6 +5047,11 @@ static void iwl3945_init_band_reference(const struct iwl3945_priv *priv, int ban
 	}
 }
 
+/**
+ * iwl3945_get_channel_info - Find driver's private channel info
+ *
+ * Based on band and channel number.
+ */
 const struct iwl3945_channel_info *iwl3945_get_channel_info(const struct iwl3945_priv *priv,
 						    int phymode, u16 channel)
 {
@@ -4953,6 +5079,9 @@ const struct iwl3945_channel_info *iwl3945_get_channel_info(const struct iwl3945
 #define CHECK_AND_PRINT(x) ((eeprom_ch_info[ch].flags & EEPROM_CHANNEL_##x) \
 			    ? # x " " : "")
 
+/**
+ * iwl3945_init_channel_map - Set up driver's info for all possible channels
+ */
 static int iwl3945_init_channel_map(struct iwl3945_priv *priv)
 {
 	int eeprom_ch_count = 0;
@@ -5062,6 +5191,7 @@ static int iwl3945_init_channel_map(struct iwl3945_priv *priv)
 		}
 	}
 
+	/* Set up txpower settings in driver for all channels */
 	if (iwl3945_txpower_set_from_eeprom(priv))
 		return -EIO;
 
@@ -8289,6 +8419,8 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 	struct ieee80211_hw *hw;
 	int i;
 
+	/* Disabling hardware scan means that mac80211 will perform scans
+	 * "the hard way", rather than using device's scan. */
 	if (iwl3945_param_disable_hw_scan) {
 		IWL_DEBUG_INFO("Disabling hw_scan\n");
 		iwl3945_hw_ops.hw_scan = NULL;
@@ -8319,6 +8451,8 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 	priv->hw = hw;
 
 	priv->pci_dev = pdev;
+
+	/* Select antenna (may be helpful if only one antenna is connected) */
 	priv->antenna = (enum iwl3945_antenna)iwl3945_param_antenna;
 #ifdef CONFIG_IWL3945_DEBUG
 	iwl3945_debug_level = iwl3945_param_debug;
@@ -8340,6 +8474,7 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 	/* Tell mac80211 our Tx characteristics */
 	hw->flags = IEEE80211_HW_HOST_GEN_BEACON_TEMPLATE;
 
+	/* 4 EDCA QOS priorities */
 	hw->queues = 4;
 
 	spin_lock_init(&priv->lock);
@@ -8360,6 +8495,7 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 
 	pci_set_master(pdev);
 
+	/* Clear the driver's (not device's) station table */
 	iwl3945_clear_stations_table(priv);
 
 	priv->data_retry_limit = -1;
@@ -8379,9 +8515,11 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 	err = pci_request_regions(pdev, DRV_NAME);
 	if (err)
 		goto out_pci_disable_device;
+
 	/* We disable the RETRY_TIMEOUT register (0x41) to keep
 	 * PCI Tx retries from interfering with C3 CPU state */
 	pci_write_config_byte(pdev, 0x41, 0x00);
+
 	priv->hw_base = pci_iomap(pdev, 0, 0);
 	if (!priv->hw_base) {
 		err = -ENODEV;
@@ -8394,6 +8532,7 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 
 	/* Initialize module parameter values here */
 
+	/* Disable radio (SW RF KILL) via parameter when loading driver */
 	if (iwl3945_param_disable) {
 		set_bit(STATUS_RF_KILL_SW, &priv->status);
 		IWL_DEBUG_INFO("Radio disabled.\n");