iwlwifi: add comments to Tx commands

Add comments to Tx commands

Clean up unused definitions in iwl-3945-commands.h

Signed-off-by: Ben Cahill <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, 175 insertions, 26 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
index 44addea5062b..cbe91dbe760c 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
@@ -937,8 +937,8 @@ struct iwl4965_rx_phy_res {
 	__le16 channel;		/* channel number */
 	__le16 non_cfg_phy[RX_RES_PHY_CNT];	/* upto 14 phy entries */
 	__le32 reserved2;
-	__le32 rate_n_flags;
-	__le16 byte_count;		/* frame's byte-count */
+	__le32 rate_n_flags;	/* RATE_MCS_* */
+	__le16 byte_count;	/* frame's byte-count */
 	__le16 reserved3;
 } __attribute__ ((packed));
 
@@ -952,41 +952,96 @@ struct iwl4965_rx_mpdu_res_start {
  * (5)
  * Tx Commands & Responses:
  *
+ * Driver must place each REPLY_TX command into one of the prioritized Tx
+ * queues in host DRAM, shared between driver and device (see comments for
+ * SCD registers and Tx/Rx Queues).  When the device's Tx scheduler and uCode
+ * are preparing to transmit, the device pulls the Tx command over the PCI
+ * bus via one of the device's Tx DMA channels, to fill an internal FIFO
+ * from which data will be transmitted.
+ *
+ * uCode handles all timing and protocol related to control frames
+ * (RTS/CTS/ACK), based on flags in the Tx command.  uCode and Tx scheduler
+ * handle reception of block-acks; uCode updates the host driver via
+ * REPLY_COMPRESSED_BA (4965).
+ *
+ * uCode handles retrying Tx when an ACK is expected but not received.
+ * This includes trying lower data rates than the one requested in the Tx
+ * command, as set up by the REPLY_RATE_SCALE (for 3945) or
+ * REPLY_TX_LINK_QUALITY_CMD (4965).
+ *
+ * Driver sets up transmit power for various rates via REPLY_TX_PWR_TABLE_CMD.
+ * This command must be executed after every RXON command, before Tx can occur.
  *****************************************************************************/
 
-/* Tx flags */
+/* REPLY_TX Tx flags field */
+
+/* 1: Use Request-To-Send protocol before this frame.
+ * Mutually exclusive vs. TX_CMD_FLG_CTS_MSK. */
 #define TX_CMD_FLG_RTS_MSK __constant_cpu_to_le32(1 << 1)
+
+/* 1: Transmit Clear-To-Send to self before this frame.
+ * Driver should set this for AUTH/DEAUTH/ASSOC-REQ/REASSOC mgmnt frames.
+ * Mutually exclusive vs. TX_CMD_FLG_RTS_MSK. */
 #define TX_CMD_FLG_CTS_MSK __constant_cpu_to_le32(1 << 2)
+
+/* 1: Expect ACK from receiving station
+ * 0: Don't expect ACK (MAC header's duration field s/b 0)
+ * Set this for unicast frames, but not broadcast/multicast. */
 #define TX_CMD_FLG_ACK_MSK __constant_cpu_to_le32(1 << 3)
+
+/* For 4965:
+ * 1: Use rate scale table (see REPLY_TX_LINK_QUALITY_CMD).
+ *    Tx command's initial_rate_index indicates first rate to try;
+ *    uCode walks through table for additional Tx attempts.
+ * 0: Use Tx rate/MCS from Tx command's rate_n_flags field.
+ *    This rate will be used for all Tx attempts; it will not be scaled. */
 #define TX_CMD_FLG_STA_RATE_MSK __constant_cpu_to_le32(1 << 4)
+
+/* 1: Expect immediate block-ack.
+ * Set when Txing a block-ack request frame.  Also set TX_CMD_FLG_ACK_MSK. */
 #define TX_CMD_FLG_IMM_BA_RSP_MASK  __constant_cpu_to_le32(1 << 6)
+
+/* 1: Frame requires full Tx-Op protection.
+ * Set this if either RTS or CTS Tx Flag gets set. */
 #define TX_CMD_FLG_FULL_TXOP_PROT_MSK __constant_cpu_to_le32(1 << 7)
+
+/* Tx antenna selection field; used only for 3945, reserved (0) for 4965.
+ * Set field to "0" to allow 3945 uCode to select antenna (normal usage). */
 #define TX_CMD_FLG_ANT_SEL_MSK __constant_cpu_to_le32(0xf00)
 #define TX_CMD_FLG_ANT_A_MSK __constant_cpu_to_le32(1 << 8)
 #define TX_CMD_FLG_ANT_B_MSK __constant_cpu_to_le32(1 << 9)
 
-/* ucode ignores BT priority for this frame */
+/* 1: Ignore Bluetooth priority for this frame.
+ * 0: Delay Tx until Bluetooth device is done (normal usage). */
 #define TX_CMD_FLG_BT_DIS_MSK __constant_cpu_to_le32(1 << 12)
 
-/* ucode overrides sequence control */
+/* 1: uCode overrides sequence control field in MAC header.
+ * 0: Driver provides sequence control field in MAC header.
+ * Set this for management frames, non-QOS data frames, non-unicast frames,
+ * and also in Tx command embedded in REPLY_SCAN_CMD for active scans. */
 #define TX_CMD_FLG_SEQ_CTL_MSK __constant_cpu_to_le32(1 << 13)
 
-/* signal that this frame is non-last MPDU */
+/* 1: This frame is non-last MPDU; more fragments are coming.
+ * 0: Last fragment, or not using fragmentation. */
 #define TX_CMD_FLG_MORE_FRAG_MSK __constant_cpu_to_le32(1 << 14)
 
-/* calculate TSF in outgoing frame */
+/* 1: uCode calculates and inserts Timestamp Function (TSF) in outgoing frame.
+ * 0: No TSF required in outgoing frame.
+ * Set this for transmitting beacons and probe responses. */
 #define TX_CMD_FLG_TSF_MSK __constant_cpu_to_le32(1 << 16)
 
-/* activate TX calibration. */
-#define TX_CMD_FLG_CALIB_MSK __constant_cpu_to_le32(1 << 17)
-
-/* signals that 2 bytes pad was inserted
-   after the MAC header */
+/* 1: Driver inserted 2 bytes pad after the MAC header, for (required) dword
+ *    alignment of frame's payload data field.
+ * 0: No pad
+ * Set this for MAC headers with 26 or 30 bytes, i.e. those with QOS or ADDR4
+ * field (but not both).  Driver must align frame data (i.e. data following
+ * MAC header) to DWORD boundary. */
 #define TX_CMD_FLG_MH_PAD_MSK __constant_cpu_to_le32(1 << 20)
 
 /* HCCA-AP - disable duration overwriting. */
 #define TX_CMD_FLG_DUR_MSK __constant_cpu_to_le32(1 << 25)
 
+
 /*
  * TX command security control
  */
@@ -998,12 +1053,13 @@ struct iwl4965_rx_mpdu_res_start {
 #define TX_CMD_SEC_KEY128	0x08
 
 /*
- * TX command Frame life time
+ * 4965 uCode updates these Tx attempt count values in host DRAM.
+ * Used for managing Tx retries when expecting block-acks.
+ * Driver should set these fields to 0.
  */
-
 struct iwl4965_dram_scratch {
-	u8 try_cnt;
-	u8 bt_kill_cnt;
+	u8 try_cnt;		/* Tx attempts */
+	u8 bt_kill_cnt;		/* Tx attempts blocked by Bluetooth device */
 	__le16 reserved;
 } __attribute__ ((packed));
 
@@ -1011,13 +1067,47 @@ struct iwl4965_dram_scratch {
  * REPLY_TX = 0x1c (command)
  */
 struct iwl4965_tx_cmd {
+	/*
+	 * MPDU byte count:
+	 * MAC header (24/26/30/32 bytes) + 2 bytes pad if 26/30 header size,
+	 * + 8 byte IV for CCM or TKIP (not used for WEP)
+	 * + Data payload
+	 * + 8-byte MIC (not used for CCM/WEP)
+	 * NOTE:  Does not include Tx command bytes, post-MAC pad bytes,
+	 *        MIC (CCM) 8 bytes, ICV (WEP/TKIP/CKIP) 4 bytes, CRC 4 bytes.i
+	 * Range: 14-2342 bytes.
+	 */
 	__le16 len;
+
+	/*
+	 * MPDU or MSDU byte count for next frame.
+	 * Used for fragmentation and bursting, but not 11n aggregation.
+	 * Same as "len", but for next frame.  Set to 0 if not applicable.
+	 */
 	__le16 next_frame_len;
-	__le32 tx_flags;
+
+	__le32 tx_flags;	/* TX_CMD_FLG_* */
+
+	/* 4965's uCode may modify this field of the Tx command (in host DRAM!).
+	 * Driver must also set dram_lsb_ptr and dram_msb_ptr in this cmd. */
 	struct iwl4965_dram_scratch scratch;
-	__le32 rate_n_flags;
+
+	/* Rate for *all* Tx attempts, if TX_CMD_FLG_STA_RATE_MSK is cleared. */
+	__le32 rate_n_flags;	/* RATE_MCS_* */
+
+	/* Index of destination station in uCode's station table */
 	u8 sta_id;
-	u8 sec_ctl;
+
+	/* Type of security encryption:  CCM or TKIP */
+	u8 sec_ctl;		/* TX_CMD_SEC_* */
+
+	/*
+	 * Index into rate table (see REPLY_TX_LINK_QUALITY_CMD) for initial
+	 * Tx attempt, if TX_CMD_FLG_STA_RATE_MSK is set.  Normally "0" for
+	 * data frames, this field may be used to selectively reduce initial
+	 * rate (via non-0 value) for special frames (e.g. management), while
+	 * still supporting rate scaling for all frames.
+	 */
 	u8 initial_rate_index;
 	u8 reserved;
 	u8 key[16];
@@ -1027,8 +1117,12 @@ struct iwl4965_tx_cmd {
 		__le32 life_time;
 		__le32 attempt;
 	} stop_time;
+
+	/* Host DRAM physical address pointer to "scratch" in this command.
+	 * Must be dword aligned.  "0" in dram_lsb_ptr disables usage. */
 	__le32 dram_lsb_ptr;
 	u8 dram_msb_ptr;
+
 	u8 rts_retry_limit;	/*byte 50 */
 	u8 data_retry_limit;	/*byte 51 */
 	u8 tid_tspec;
@@ -1036,7 +1130,17 @@ struct iwl4965_tx_cmd {
 		__le16 pm_frame_timeout;
 		__le16 attempt_duration;
 	} timeout;
+
+	/*
+	 * Duration of EDCA burst Tx Opportunity, in 32-usec units.
+	 * Set this if txop time is not specified by HCCA protocol (e.g. by AP).
+	 */
 	__le16 driver_txop;
+
+	/*
+	 * MAC header goes here, followed by 2 bytes padding if MAC header
+	 * length is 26 or 30 bytes, followed by payload data
+	 */
 	u8 payload[0];
 	struct ieee80211_hdr hdr[0];
 } __attribute__ ((packed));
@@ -1109,7 +1213,7 @@ enum {
 };
 
 /* *******************************
- * TX aggregation state
+ * TX aggregation status
  ******************************* */
 
 enum {
@@ -1133,35 +1237,80 @@ enum {
  AGG_TX_STATE_LAST_SENT_TRY_CNT_MSK | \
  AGG_TX_STATE_LAST_SENT_BT_KILL_MSK)
 
+/* # tx attempts for first frame in aggregation */
 #define AGG_TX_STATE_TRY_CNT_POS 12
 #define AGG_TX_STATE_TRY_CNT_MSK 0xf000
 
+/* Command ID and sequence number of Tx command for this frame */
 #define AGG_TX_STATE_SEQ_NUM_POS 16
 #define AGG_TX_STATE_SEQ_NUM_MSK 0xffff0000
 
 /*
  * REPLY_TX = 0x1c (response)
+ *
+ * This response may be in one of two slightly different formats, indicated
+ * by the frame_count field:
+ *
+ * 1)  No aggregation (frame_count == 1).  This reports Tx results for
+ *     a single frame.  Multiple attempts, at various bit rates, may have
+ *     been made for this frame.
+ *
+ * 2)  Aggregation (frame_count > 1).  This reports Tx results for
+ *     2 or more frames that used block-acknowledge.  All frames were
+ *     transmitted at same rate.  Rate scaling may have been used if first
+ *     frame in this new agg block failed in previous agg block(s).
+ *
+ *     Note that, for aggregation, ACK (block-ack) status is not delivered here;
+ *     block-ack has not been received by the time the 4965 records this status.
+ *     This status relates to reasons the tx might have been blocked or aborted
+ *     within the sending station (this 4965), rather than whether it was
+ *     received successfully by the destination station.
  */
 struct iwl4965_tx_resp {
 	u8 frame_count;		/* 1 no aggregation, >1 aggregation */
-	u8 bt_kill_count;
-	u8 failure_rts;
-	u8 failure_frame;
-	__le32 rate_n_flags;
-	__le16 wireless_media_time;
+	u8 bt_kill_count;	/* # blocked by bluetooth (unused for agg) */
+	u8 failure_rts;		/* # failures due to unsuccessful RTS */
+	u8 failure_frame;	/* # failures due to no ACK (unused for agg) */
+
+	/* For non-agg:  Rate at which frame was successful.
+	 * For agg:  Rate at which all frames were transmitted. */
+	__le32 rate_n_flags;	/* RATE_MCS_*  */
+
+	/* For non-agg:  RTS + CTS + frame tx attempts time + ACK.
+	 * For agg:  RTS + CTS + aggregation tx time + block-ack time. */
+	__le16 wireless_media_time;	/* uSecs */
+
 	__le16 reserved;
-	__le32 pa_power1;
+	__le32 pa_power1;	/* RF power amplifier measurement (not used) */
 	__le32 pa_power2;
+
+	/*
+	 * For non-agg:  frame status TX_STATUS_*
+	 * For agg:  status of 1st frame, AGG_TX_STATE_*; other frame status
+	 *           fields follow this one, up to frame_count.
+	 *           Bit fields:
+	 *           11- 0:  AGG_TX_STATE_* status code
+	 *           15-12:  Retry count for 1st frame in aggregation (retries
+	 *                   occur if tx failed for this frame when it was a
+	 *                   member of a previous aggregation block).  If rate
+	 *                   scaling is used, retry count indicates the rate
+	 *                   table entry used for all frames in the new agg.
+	 *           31-16:  Sequence # for this frame's Tx cmd (not SSN!)
+	 */
 	__le32 status;	/* TX status (for aggregation status of 1st frame) */
 } __attribute__ ((packed));
 
 /*
  * REPLY_COMPRESSED_BA = 0xc5 (response only, not a command)
+ *
+ * Reports Block-Acknowledge from recipient station
  */
 struct iwl4965_compressed_ba_resp {
 	__le32 sta_addr_lo32;
 	__le16 sta_addr_hi16;
 	__le16 reserved;
+
+	/* Index of recipient (BA-sending) station in uCode's station table */
 	u8 sta_id;
 	u8 tid;
 	__le16 ba_seq_ctl;