From 672903b329579ff43ae3d553cf55bd82041921c1 Mon Sep 17 00:00:00 2001 From: Jouni Malinen Date: Mon, 2 Mar 2009 15:06:31 +0200 Subject: [PATCH] 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 Signed-off-by: John W. Linville --- drivers/net/wireless/ath9k/hw.c | 76 ++++++++++++++++++++++++++++++-- drivers/net/wireless/ath9k/mac.h | 8 ++-- 2 files changed, 78 insertions(+), 6 deletions(-) diff --git a/drivers/net/wireless/ath9k/hw.c b/drivers/net/wireless/ath9k/hw.c index 2acbb84dc2ba..5672f43e58e2 100644 --- a/drivers/net/wireless/ath9k/hw.c +++ b/drivers/net/wireless/ath9k/hw.c @@ -2482,18 +2482,49 @@ bool ath9k_hw_set_keycache_entry(struct ath_hw *ah, u16 entry, 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 @@ bool ath9k_hw_set_keycache_entry(struct ath_hw *ah, u16 entry, 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 862a63f7634b..fbd2d6ad2a53 100644 --- a/drivers/net/wireless/ath9k/mac.h +++ b/drivers/net/wireless/ath9k/mac.h @@ -588,9 +588,11 @@ struct ath9k_keyval { 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 {