iwlwifi: add comments to QOS and ADD_STA commands

Add comments to QOS and ADD_STA commands

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, 85 insertions, 14 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
index 0813e3e3ef6..44addea5062 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
@@ -650,6 +650,23 @@ struct iwl4965_csa_notification {
  * Quality-of-Service (QOS) Commands & Responses:
  *
  *****************************************************************************/
+
+/**
+ * struct iwl_ac_qos -- QOS timing params for REPLY_QOS_PARAM
+ * One for each of 4 EDCA access categories in struct iwl_qosparam_cmd
+ *
+ * @cw_min: Contention window, start value in numbers of slots.
+ *          Should be a power-of-2, minus 1.  Device's default is 0x0f.
+ * @cw_max: Contention window, max value in numbers of slots.
+ *          Should be a power-of-2, minus 1.  Device's default is 0x3f.
+ * @aifsn:  Number of slots in Arbitration Interframe Space (before
+ *          performing random backoff timing prior to Tx).  Device default 1.
+ * @edca_txop:  Length of Tx opportunity, in uSecs.  Device default is 0.
+ *
+ * Device will automatically increase contention window by (2*CW) + 1 for each
+ * transmission retry.  Device uses cw_max as a bit mask, ANDed with new CW
+ * value, to cap the CW value.
+ */
 struct iwl4965_ac_qos {
         __le16 cw_min;
         __le16 cw_max;
@@ -663,14 +680,14 @@ struct iwl4965_ac_qos {
 #define QOS_PARAM_FLG_TGN_MSK           __constant_cpu_to_le32(0x02)
 #define QOS_PARAM_FLG_TXOP_TYPE_MSK     __constant_cpu_to_le32(0x10)
 
-/*
- *  TXFIFO Queue number defines
- */
-/* number of Access categories (AC) (EDCA), queues 0..3 */
+/* Number of Access Categories (AC) (EDCA), queues 0..3 */
 #define AC_NUM                4
 
 /*
  * REPLY_QOS_PARAM = 0x13 (command, has simple generic response)
+ *
+ * This command sets up timings for each of the 4 prioritized EDCA Tx FIFOs
+ * 0: Background, 1: Best Effort, 2: Video, 3: Voice.
  */
 struct iwl4965_qosparam_cmd {
         __le32 qos_flags;
@@ -685,13 +702,11 @@ struct iwl4965_qosparam_cmd {
 /*
  * Multi station support
  */
+
+/* Special, dedicated locations within device's station table */
 #define IWL_AP_ID               0
 #define IWL_MULTICAST_ID        1
 #define IWL_STA_ID              2
-
-#define IWL3945_BROADCAST_ID    24
-#define IWL3945_STATION_COUNT   25
-
 #define IWL4965_BROADCAST_ID    31
 #define IWL4965_STATION_COUNT   32
 
@@ -708,6 +723,7 @@ struct iwl4965_qosparam_cmd {
 #define STA_FLG_AGG_MPDU_DENSITY_POS    (23)
 #define STA_FLG_AGG_MPDU_DENSITY_MSK    __constant_cpu_to_le32(7 << 23)
 
+/* Use in mode field.  1: modify existing entry, 0: add new station entry */
 #define STA_CONTROL_MODIFY_MSK          0x01
 
 /* key flags __le16*/
@@ -720,12 +736,15 @@ struct iwl4965_qosparam_cmd {
 #define STA_KEY_FLG_KEYID_POS   8
 #define STA_KEY_FLG_INVALID     __constant_cpu_to_le16(0x0800)
 
-/* modify flags  */
+/* Flags indicate whether to modify vs. don't change various station params */
 #define STA_MODIFY_KEY_MASK             0x01
 #define STA_MODIFY_TID_DISABLE_TX       0x02
 #define STA_MODIFY_TX_RATE_MSK          0x04
 #define STA_MODIFY_ADDBA_TID_MSK        0x08
 #define STA_MODIFY_DELBA_TID_MSK        0x10
+
+/* Receiver address (actually, Rx station's index into station table),
+ * combined with Traffic ID (QOS priority), in format used by Tx Scheduler */
 #define BUILD_RAxTID(sta_id, tid)       (((sta_id) << 4) + (tid))
 
 struct iwl4965_keyinfo {
@@ -737,6 +756,18 @@ struct iwl4965_keyinfo {
         u8 key[16];             /* 16-byte unicast decryption key */
 } __attribute__ ((packed));
 
+/**
+ * struct sta_id_modify
+ * @addr[ETH_ALEN]: station's MAC address
+ * @sta_id: index of station in uCode's station table
+ * @modify_mask: STA_MODIFY_*, 1: modify, 0: don't change
+ *
+ * Driver selects unused table index when adding new station,
+ * or the index to a pre-existing station entry when modifying that station.
+ * Some indexes have special purposes (IWL_AP_ID, index 0, is for AP).
+ *
+ * modify_mask flags select which parameters to modify vs. leave alone.
+ */
 struct sta_id_modify {
         u8 addr[ETH_ALEN];
         __le16 reserved1;
@@ -747,30 +778,70 @@ struct sta_id_modify {
 
 /*
  * REPLY_ADD_STA = 0x18 (command)
+ *
+ * The device contains an internal table of per-station information,
+ * with info on security keys, aggregation parameters, and Tx rates for
+ * initial Tx attempt and any retries (4965 uses REPLY_TX_LINK_QUALITY_CMD,
+ * 3945 uses REPLY_RATE_SCALE to set up rate tables).
+ *
+ * REPLY_ADD_STA sets up the table entry for one station, either creating
+ * a new entry, or modifying a pre-existing one.
+ *
+ * NOTE:  RXON command (without "associated" bit set) wipes the station table
+ *        clean.  Moving into RF_KILL state does this also.  Driver must set up
+ *        new station table before transmitting anything on the RXON channel
+ *        (except active scans or active measurements; those commands carry
+ *        their own txpower/rate setup data).
+ *
+ *        When getting started on a new channel, driver must set up the
+ *        IWL_BROADCAST_ID entry (last entry in the table).  For a client
+ *        station in a BSS, once an AP is selected, driver sets up the AP STA
+ *        in the IWL_AP_ID entry (1st entry in the table).  BROADCAST and AP
+ *        are all that are needed for a BSS client station.  If the device is
+ *        used as AP, or in an IBSS network, driver must set up station table
+ *        entries for all STAs in network, starting with index IWL_STA_ID.
  */
 struct iwl4965_addsta_cmd {
-        u8 mode;
+        u8 mode;                /* 1: modify existing, 0: add new station */
         u8 reserved[3];
         struct sta_id_modify sta;
         struct iwl4965_keyinfo key;
-        __le32 station_flags;
-        __le32 station_flags_msk;
+        __le32 station_flags;           /* STA_FLG_* */
+        __le32 station_flags_msk;       /* STA_FLG_* */
+
+        /* bit field to disable (1) or enable (0) Tx for Traffic ID (TID)
+         * corresponding to bit (e.g. bit 5 controls TID 5).
+         * Set modify_mask bit STA_MODIFY_TID_DISABLE_TX to use this field. */
         __le16 tid_disable_tx;
+
         __le16  reserved1;
+
+        /* TID for which to add block-ack support.
+         * Set modify_mask bit STA_MODIFY_ADDBA_TID_MSK to use this field. */
         u8 add_immediate_ba_tid;
+
+        /* TID for which to remove block-ack support.
+         * Set modify_mask bit STA_MODIFY_DELBA_TID_MSK to use this field. */
         u8 remove_immediate_ba_tid;
+
+        /* Starting Sequence Number for added block-ack support.
+         * Set modify_mask bit STA_MODIFY_ADDBA_TID_MSK to use this field. */
         __le16 add_immediate_ba_ssn;
+
         __le32 reserved2;
 } __attribute__ ((packed));
 
+#define ADD_STA_SUCCESS_MSK             0x1
+#define ADD_STA_NO_ROOM_IN_TABLE        0x2
+#define ADD_STA_NO_BLOCK_ACK_RESOURCE   0x4
+#define ADD_STA_MODIFY_NON_EXIST_STA    0x8
 /*
  * REPLY_ADD_STA = 0x18 (response)
  */
 struct iwl4965_add_sta_resp {
-        u8 status;
+        u8 status;      /* ADD_STA_* */
 } __attribute__ ((packed));
 
-#define ADD_STA_SUCCESS_MSK              0x1
 
 /******************************************************************************
  * (4)