iwlwifi: document command header and "alive" responses

Document command header and "alive" responses

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, 126 insertions, 34 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
index 9910939f5a32..bde3aa018bba 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
@@ -120,7 +120,7 @@ enum {
         REPLY_TX_PWR_TABLE_CMD = 0x97,
         MEASURE_ABORT_NOTIFICATION = 0x99,      /* not used */
 
-        /* BT config command */
+        /* Bluetooth device coexistance config command */
         REPLY_BT_CONFIG = 0x9b,
 
         /* 4965 Statistics */
@@ -151,25 +151,42 @@ enum {
  *
  *****************************************************************************/
 
+/* iwl4965_cmd_header flags value */
 #define IWL_CMD_FAILED_MSK 0x40
 
+/**
+ * struct iwl4965_cmd_header
+ *
+ * This header format appears in the beginning of each command sent from the
+ * driver, and each response/notification received from uCode.
+ */
 struct iwl4965_cmd_header {
-        u8 cmd;
-        u8 flags;
-        /* We have 15 LSB to use as we please (MSB indicates
-         * a frame Rx'd from the HW).  We encode the following
-         * information into the sequence field:
+        u8 cmd;         /* Command ID:  REPLY_RXON, etc. */
+        u8 flags;       /* IWL_CMD_* */
+        /*
+         * The driver sets up the sequence number to values of its chosing.
+         * uCode does not use this value, but passes it back to the driver
+         * when sending the response to each driver-originated command, so
+         * the driver can match the response to the command.  Since the values
+         * don't get used by uCode, the driver may set up an arbitrary format.
          *
-         *  0:7    index in fifo
-         *  8:13   fifo selection
-         * 14:14   bit indicating if this packet references the 'extra'
-         *         storage at the end of the memory queue
-         * 15:15   (Rx indication)
+         * There is one exception:  uCode sets bit 15 when it originates
+         * the response/notification, i.e. when the response/notification
+         * is not a direct response to a command sent by the driver.  For
+         * example, uCode issues REPLY_3945_RX when it sends a received frame
+         * to the driver; it is not a direct response to any driver command.
          *
+         * The Linux driver uses the following format:
+         *
+         *  0:7    index/position within Tx queue
+         *  8:13   Tx queue selection
+         * 14:14   driver sets this to indicate command is in the 'huge'
+         *         storage at the end of the command buffers, i.e. scan cmd
+         * 15:15   uCode sets this in uCode-originated response/notification
          */
         __le16 sequence;
 
-        /* command data follows immediately */
+        /* command or response/notification data follows immediately */
         u8 data[0];
 } __attribute__ ((packed));
 
@@ -218,28 +235,28 @@ struct iwl4965_cmd_header {
 #define RATE_MCS_HT_DUP_POS 5
 #define RATE_MCS_HT_DUP_MSK 0x20
 
-/* (1) HT format, (0) legacy format in bits 7:0 */
+/* Bit 8: (1) HT format, (0) legacy format in bits 7:0 */
 #define RATE_MCS_FLAGS_POS 8
 #define RATE_MCS_HT_POS 8
 #define RATE_MCS_HT_MSK 0x100
 
-/* (1) CCK, (0) OFDM.  HT (bit 8) must be "0" for this bit to be valid */
+/* Bit 9: (1) CCK, (0) OFDM.  HT (bit 8) must be "0" for this bit to be valid */
 #define RATE_MCS_CCK_POS 9
 #define RATE_MCS_CCK_MSK 0x200
 
-/* (1) Use Green Field preamble */
+/* Bit 10: (1) Use Green Field preamble */
 #define RATE_MCS_GF_POS 10
 #define RATE_MCS_GF_MSK 0x400
 
-/* (1) Use 40Mhz FAT channel width, (0) use 20 MHz legacy channel width */
+/* Bit 11: (1) Use 40Mhz FAT chnl width, (0) use 20 MHz legacy chnl width */
 #define RATE_MCS_FAT_POS 11
 #define RATE_MCS_FAT_MSK 0x800
 
-/* (1) Duplicate data on both 20MHz channels.  FAT (bit 11) must be set. */
+/* Bit 12: (1) Duplicate data on both 20MHz chnls.  FAT (bit 11) must be set. */
 #define RATE_MCS_DUP_POS 12
 #define RATE_MCS_DUP_MSK 0x1000
 
-/* (1) Short guard interval (0.4 usec), (0) normal GI (0.8 usec) */
+/* Bit 13: (1) Short guard interval (0.4 usec), (0) normal GI (0.8 usec) */
 #define RATE_MCS_SGI_POS 13
 #define RATE_MCS_SGI_MSK 0x2000
 
@@ -266,45 +283,120 @@ struct iwl4965_cmd_header {
 #define INITIALIZE_SUBTYPE    (9)
 
 /*
- * REPLY_ALIVE = 0x1 (response only, not a command)
+ * ("Initialize") REPLY_ALIVE = 0x1 (response only, not a command)
+ *
+ * uCode issues this "initialize alive" notification once the initialization
+ * uCode image has completed its work, and is ready to load the runtime image.
+ * This is the *first* "alive" notification that the driver will receive after
+ * rebooting uCode; the "initialize" alive is indicated by subtype field == 9.
+ *
+ * See comments documenting "BSM" (bootstrap state machine).
+ *
+ * For 4965, this notification contains important calibration data for
+ * calculating txpower settings:
+ *
+ * 1)  Power supply voltage indication.  The voltage sensor outputs higher
+ *     values for lower voltage, and vice versa.
+ *
+ * 2)  Temperature measurement parameters, for each of two channel widths
+ *     (20 MHz and 40 MHz) supported by the radios.  Temperature sensing
+ *     is done via one of the receiver chains, and channel width influences
+ *     the results.
+ *
+ * 3)  Tx gain compensation to balance 4965's 2 Tx chains for MIMO operation,
+ *     for each of 5 frequency ranges.
  */
-struct iwl4965_alive_resp {
+struct iwl4965_init_alive_resp {
         u8 ucode_minor;
         u8 ucode_major;
         __le16 reserved1;
         u8 sw_rev[8];
         u8 ver_type;
-        u8 ver_subtype;
+        u8 ver_subtype;         /* "9" for initialize alive */
         __le16 reserved2;
         __le32 log_event_table_ptr;
         __le32 error_event_table_ptr;
         __le32 timestamp;
         __le32 is_valid;
+
+        /* calibration values from "initialize" uCode */
+        __le32 voltage;         /* signed, higher value is lower voltage */
+        __le32 therm_r1[2];     /* signed, 1st for normal, 2nd for FAT channel*/
+        __le32 therm_r2[2];     /* signed */
+        __le32 therm_r3[2];     /* signed */
+        __le32 therm_r4[2];     /* signed */
+        __le32 tx_atten[5][2];  /* signed MIMO gain comp, 5 freq groups,
+                                 * 2 Tx chains */
 } __attribute__ ((packed));
 
-struct iwl4965_init_alive_resp {
+
+/**
+ * REPLY_ALIVE = 0x1 (response only, not a command)
+ *
+ * uCode issues this "alive" notification once the runtime image is ready
+ * to receive commands from the driver.  This is the *second* "alive"
+ * notification that the driver will receive after rebooting uCode;
+ * this "alive" is indicated by subtype field != 9.
+ *
+ * See comments documenting "BSM" (bootstrap state machine).
+ *
+ * This response includes two pointers to structures within the device's
+ * data SRAM (access via HBUS_TARG_MEM_* regs) that are useful for debugging:
+ *
+ * 1)  log_event_table_ptr indicates base of the event log.  This traces
+ *     a 256-entry history of uCode execution within a circular buffer.
+ *     Its header format is:
+ *
+ *      __le32 log_size;     log capacity (in number of entries)
+ *      __le32 type;         (1) timestamp with each entry, (0) no timestamp
+ *      __le32 wraps;        # times uCode has wrapped to top of circular buffer
+ *      __le32 write_index;  next circular buffer entry that uCode would fill
+ *
+ *     The header is followed by the circular buffer of log entries.  Entries
+ *     with timestamps have the following format:
+ *
+ *      __le32 event_id;     range 0 - 1500
+ *      __le32 timestamp;    low 32 bits of TSF (of network, if associated)
+ *      __le32 data;         event_id-specific data value
+ *
+ *     Entries without timestamps contain only event_id and data.
+ *
+ * 2)  error_event_table_ptr indicates base of the error log.  This contains
+ *     information about any uCode error that occurs.  For 4965, the format
+ *     of the error log is:
+ *
+ *      __le32 valid;        (nonzero) valid, (0) log is empty
+ *      __le32 error_id;     type of error
+ *      __le32 pc;           program counter
+ *      __le32 blink1;       branch link
+ *      __le32 blink2;       branch link
+ *      __le32 ilink1;       interrupt link
+ *      __le32 ilink2;       interrupt link
+ *      __le32 data1;        error-specific data
+ *      __le32 data2;        error-specific data
+ *      __le32 line;         source code line of error
+ *      __le32 bcon_time;    beacon timer
+ *      __le32 tsf_low;      network timestamp function timer
+ *      __le32 tsf_hi;       network timestamp function timer
+ *
+ * The Linux driver can print both logs to the system log when a uCode error
+ * occurs.
+ */
+struct iwl4965_alive_resp {
         u8 ucode_minor;
         u8 ucode_major;
         __le16 reserved1;
         u8 sw_rev[8];
         u8 ver_type;
-        u8 ver_subtype;
+        u8 ver_subtype;                 /* not "9" for runtime alive */
         __le16 reserved2;
-        __le32 log_event_table_ptr;
-        __le32 error_event_table_ptr;
+        __le32 log_event_table_ptr;     /* SRAM address for event log */
+        __le32 error_event_table_ptr;   /* SRAM address for error log */
         __le32 timestamp;
         __le32 is_valid;
-
-        /* calibration values from "initialize" uCode */
-        __le32 voltage;         /* signed */
-        __le32 therm_r1[2];     /* signed 1st for normal, 2nd for FAT channel */
-        __le32 therm_r2[2];     /* signed */
-        __le32 therm_r3[2];     /* signed */
-        __le32 therm_r4[2];     /* signed */
-        __le32 tx_atten[5][2];  /* signed MIMO gain comp, 5 freq groups,
-                                 * 2 Tx chains */
 } __attribute__ ((packed));
 
+
 union tsf {
         u8 byte[8];
         __le16 word[4];