ath9k: Document keycache operations
There are number of small details about the keycache operations that
are very easy to miss (and forget), so better include detailed
comments in ath9k_hw_set_keycache_entry() to avoid having to figure
out this every time when having to touch this area.
Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath9k/hw.c b/drivers/net/wireless/ath9k/hw.c
index 2acbb84..5672f43 100644
--- a/drivers/net/wireless/ath9k/hw.c
+++ b/drivers/net/wireless/ath9k/hw.c
@@ -2482,18 +2482,49 @@
if (k->kv_len <= LEN_WEP104)
key4 &= 0xff;
+ /*
+ * Note: Key cache registers access special memory area that requires
+ * two 32-bit writes to actually update the values in the internal
+ * memory. Consequently, the exact order and pairs used here must be
+ * maintained.
+ */
+
if (keyType == AR_KEYTABLE_TYPE_TKIP && ATH9K_IS_MIC_ENABLED(ah)) {
u16 micentry = entry + 64;
+ /*
+ * Write inverted key[47:0] first to avoid Michael MIC errors
+ * on frames that could be sent or received at the same time.
+ * The correct key will be written in the end once everything
+ * else is ready.
+ */
REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), ~key0);
REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), ~key1);
+
+ /* Write key[95:48] */
REG_WRITE(ah, AR_KEYTABLE_KEY2(entry), key2);
REG_WRITE(ah, AR_KEYTABLE_KEY3(entry), key3);
+
+ /* Write key[127:96] and key type */
REG_WRITE(ah, AR_KEYTABLE_KEY4(entry), key4);
REG_WRITE(ah, AR_KEYTABLE_TYPE(entry), keyType);
+
+ /* Write MAC address for the entry */
(void) ath9k_hw_keysetmac(ah, entry, mac);
if (ah->misc_mode & AR_PCU_MIC_NEW_LOC_ENA) {
+ /*
+ * TKIP uses two key cache entries:
+ * Michael MIC TX/RX keys in the same key cache entry
+ * (idx = main index + 64):
+ * key0 [31:0] = RX key [31:0]
+ * key1 [15:0] = TX key [31:16]
+ * key1 [31:16] = reserved
+ * key2 [31:0] = RX key [63:32]
+ * key3 [15:0] = TX key [15:0]
+ * key3 [31:16] = reserved
+ * key4 [31:0] = TX key [63:32]
+ */
u32 mic0, mic1, mic2, mic3, mic4;
mic0 = get_unaligned_le32(k->kv_mic + 0);
@@ -2501,45 +2532,84 @@
mic1 = get_unaligned_le16(k->kv_txmic + 2) & 0xffff;
mic3 = get_unaligned_le16(k->kv_txmic + 0) & 0xffff;
mic4 = get_unaligned_le32(k->kv_txmic + 4);
+
+ /* Write RX[31:0] and TX[31:16] */
REG_WRITE(ah, AR_KEYTABLE_KEY0(micentry), mic0);
REG_WRITE(ah, AR_KEYTABLE_KEY1(micentry), mic1);
+
+ /* Write RX[63:32] and TX[15:0] */
REG_WRITE(ah, AR_KEYTABLE_KEY2(micentry), mic2);
REG_WRITE(ah, AR_KEYTABLE_KEY3(micentry), mic3);
+
+ /* Write TX[63:32] and keyType(reserved) */
REG_WRITE(ah, AR_KEYTABLE_KEY4(micentry), mic4);
REG_WRITE(ah, AR_KEYTABLE_TYPE(micentry),
AR_KEYTABLE_TYPE_CLR);
} else {
+ /*
+ * TKIP uses four key cache entries (two for group
+ * keys):
+ * Michael MIC TX/RX keys are in different key cache
+ * entries (idx = main index + 64 for TX and
+ * main index + 32 + 96 for RX):
+ * key0 [31:0] = TX/RX MIC key [31:0]
+ * key1 [31:0] = reserved
+ * key2 [31:0] = TX/RX MIC key [63:32]
+ * key3 [31:0] = reserved
+ * key4 [31:0] = reserved
+ *
+ * Upper layer code will call this function separately
+ * for TX and RX keys when these registers offsets are
+ * used.
+ */
u32 mic0, mic2;
mic0 = get_unaligned_le32(k->kv_mic + 0);
mic2 = get_unaligned_le32(k->kv_mic + 4);
+
+ /* Write MIC key[31:0] */
REG_WRITE(ah, AR_KEYTABLE_KEY0(micentry), mic0);
REG_WRITE(ah, AR_KEYTABLE_KEY1(micentry), 0);
+
+ /* Write MIC key[63:32] */
REG_WRITE(ah, AR_KEYTABLE_KEY2(micentry), mic2);
REG_WRITE(ah, AR_KEYTABLE_KEY3(micentry), 0);
+
+ /* Write TX[63:32] and keyType(reserved) */
REG_WRITE(ah, AR_KEYTABLE_KEY4(micentry), 0);
REG_WRITE(ah, AR_KEYTABLE_TYPE(micentry),
AR_KEYTABLE_TYPE_CLR);
}
+
+ /* MAC address registers are reserved for the MIC entry */
REG_WRITE(ah, AR_KEYTABLE_MAC0(micentry), 0);
REG_WRITE(ah, AR_KEYTABLE_MAC1(micentry), 0);
+
+ /*
+ * Write the correct (un-inverted) key[47:0] last to enable
+ * TKIP now that all other registers are set with correct
+ * values.
+ */
REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), key0);
REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), key1);
} else {
+ /* Write key[47:0] */
REG_WRITE(ah, AR_KEYTABLE_KEY0(entry), key0);
REG_WRITE(ah, AR_KEYTABLE_KEY1(entry), key1);
+
+ /* Write key[95:48] */
REG_WRITE(ah, AR_KEYTABLE_KEY2(entry), key2);
REG_WRITE(ah, AR_KEYTABLE_KEY3(entry), key3);
+
+ /* Write key[127:96] and key type */
REG_WRITE(ah, AR_KEYTABLE_KEY4(entry), key4);
REG_WRITE(ah, AR_KEYTABLE_TYPE(entry), keyType);
+ /* Write MAC address for the entry */
(void) ath9k_hw_keysetmac(ah, entry, mac);
}
- if (ah->curchan == NULL)
- return true;
-
return true;
}
diff --git a/drivers/net/wireless/ath9k/mac.h b/drivers/net/wireless/ath9k/mac.h
index 862a63f..fbd2d6a 100644
--- a/drivers/net/wireless/ath9k/mac.h
+++ b/drivers/net/wireless/ath9k/mac.h
@@ -588,9 +588,11 @@
u8 kv_type;
u8 kv_pad;
u16 kv_len;
- u8 kv_val[16];
- u8 kv_mic[8];
- u8 kv_txmic[8];
+ u8 kv_val[16]; /* TK */
+ u8 kv_mic[8]; /* Michael MIC key */
+ u8 kv_txmic[8]; /* Michael MIC TX key (used only if the hardware
+ * supports both MIC keys in the same key cache entry;
+ * in that case, kv_mic is the RX key) */
};
enum ath9k_key_type {