rt2800: Add documentation on MCU requests

Add documentation on MCU communication, some of known commands and
their arguments. Supplement command ids.
Signed-off-by: NJakub Kicinski <kubakici@wp.pl>
Acked-by: NIvo van Doorn <IvDoorn@gmail.com>
Acked-by: NGertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800.h

@@ -1637,6 +1637,7 @@ struct mac_iveiv_entry {
 
 /*
  * H2M_MAILBOX_CSR: Host-to-MCU Mailbox.
+ * CMD_TOKEN: Command id, 0xff disable status reporting.
  */
 #define H2M_MAILBOX_CSR			0x7010
 #define H2M_MAILBOX_CSR_ARG0		FIELD32(0x000000ff)
@@ -1646,6 +1647,8 @@ struct mac_iveiv_entry {
 
 /*
  * H2M_MAILBOX_CID:
+ * Free slots contain 0xff. MCU will store command's token to lowest free slot.
+ * If all slots are occupied status will be dropped.
  */
 #define H2M_MAILBOX_CID			0x7014
 #define H2M_MAILBOX_CID_CMD0		FIELD32(0x000000ff)
@@ -1655,6 +1658,7 @@ struct mac_iveiv_entry {
 
 /*
  * H2M_MAILBOX_STATUS:
+ * Command status will be saved to same slot as command id.
  */
 #define H2M_MAILBOX_STATUS		0x701c
 
@@ -2298,6 +2302,12 @@ struct mac_iveiv_entry {
 
 /*
  * MCU mailbox commands.
+ * MCU_SLEEP - go to power-save mode.
+ *             arg1: 1: save as much power as possible, 0: save less power.
+ *             status: 1: success, 2: already asleep,
+ *                     3: maybe MAC is busy so can't finish this task.
+ * MCU_RADIO_OFF
+ *             arg0: 0: do power-saving, NOT turn off radio.
  */
 #define MCU_SLEEP			0x30
 #define MCU_WAKEUP			0x31
@@ -2318,7 +2328,10 @@ struct mac_iveiv_entry {
 /*
  * MCU mailbox tokens
  */
-#define TOKEN_WAKUP			3
+#define TOKEN_SLEEP			1
+#define TOKEN_RADIO_OFF			2
+#define TOKEN_WAKEUP			3
+
 
 /*
  * DMA descriptor defines.

drivers/net/wireless/rt2x00/rt2800pci.c

@@ -522,14 +522,16 @@ static int rt2800pci_set_state(struct rt2x00_dev *rt2x00dev,
 			       enum dev_state state)
 {
 	if (state == STATE_AWAKE) {
-		rt2800_mcu_request(rt2x00dev, MCU_WAKEUP, TOKEN_WAKUP, 0, 0x02);
-		rt2800pci_mcu_status(rt2x00dev, TOKEN_WAKUP);
+		rt2800_mcu_request(rt2x00dev, MCU_WAKEUP, TOKEN_WAKEUP,
+				   0, 0x02);
+		rt2800pci_mcu_status(rt2x00dev, TOKEN_WAKEUP);
 	} else if (state == STATE_SLEEP) {
 		rt2x00pci_register_write(rt2x00dev, H2M_MAILBOX_STATUS,
 					 0xffffffff);
 		rt2x00pci_register_write(rt2x00dev, H2M_MAILBOX_CID,
 					 0xffffffff);
-		rt2800_mcu_request(rt2x00dev, MCU_SLEEP, 0x01, 0xff, 0x01);
+		rt2800_mcu_request(rt2x00dev, MCU_SLEEP, TOKEN_SLEEP,
+				   0xff, 0x01);
 	}
 
 	return 0;