Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6 into for-davem

1 files changed, 98 insertions, 1 deletions

diff --git a/drivers/net/wireless/ath/ath5k/pcu.c b/drivers/net/wireless/ath/ath5k/pcu.c
index 6a891c4484a0..095d30b50ec7 100644
--- a/drivers/net/wireless/ath/ath5k/pcu.c
+++ b/drivers/net/wireless/ath/ath5k/pcu.c
@@ -495,6 +495,10 @@ u64 ath5k_hw_get_tsf64(struct ath5k_hw *ah)
 {
         u32 tsf_lower, tsf_upper1, tsf_upper2;
         int i;
+        unsigned long flags;
+
+        /* This code is time critical - we don't want to be interrupted here */
+        local_irq_save(flags);
 
         /*
          * While reading TSF upper and then lower part, the clock is still
@@ -517,6 +521,8 @@ u64 ath5k_hw_get_tsf64(struct ath5k_hw *ah)
                 tsf_upper1 = tsf_upper2;
         }
 
+        local_irq_restore(flags);
+
         WARN_ON( i == ATH5K_MAX_TSF_READ );
 
         return (((u64)tsf_upper1 << 32) | tsf_lower);
@@ -600,7 +606,7 @@ void ath5k_hw_init_beacon(struct ath5k_hw *ah, u32 next_beacon, u32 interval)
         /* Timer3 marks the end of our ATIM window
          * a zero length window is not allowed because
          * we 'll get no beacons */
-        timer3 = next_beacon + (ah->ah_atim_window ? ah->ah_atim_window : 1);
+        timer3 = next_beacon + 1;
 
         /*
          * Set the beacon register and enable all timers.
@@ -641,6 +647,97 @@ void ath5k_hw_init_beacon(struct ath5k_hw *ah, u32 next_beacon, u32 interval)
 }
 
 /**
+ * ath5k_check_timer_win - Check if timer B is timer A + window
+ *
+ * @a: timer a (before b)
+ * @b: timer b (after a)
+ * @window: difference between a and b
+ * @intval: timers are increased by this interval
+ *
+ * This helper function checks if timer B is timer A + window and covers
+ * cases where timer A or B might have already been updated or wrapped
+ * around (Timers are 16 bit).
+ *
+ * Returns true if O.K.
+ */
+static inline bool
+ath5k_check_timer_win(int a, int b, int window, int intval)
+{
+        /*
+         * 1.) usually B should be A + window
+         * 2.) A already updated, B not updated yet
+         * 3.) A already updated and has wrapped around
+         * 4.) B has wrapped around
+         */
+        if ((b - a == window) ||                                /* 1.) */
+            (a - b == intval - window) ||                       /* 2.) */
+            ((a | 0x10000) - b == intval - window) ||           /* 3.) */
+            ((b | 0x10000) - a == window))                      /* 4.) */
+                return true; /* O.K. */
+        return false;
+}
+
+/**
+ * ath5k_hw_check_beacon_timers - Check if the beacon timers are correct
+ *
+ * @ah: The &struct ath5k_hw
+ * @intval: beacon interval
+ *
+ * This is a workaround for IBSS mode:
+ *
+ * The need for this function arises from the fact that we have 4 separate
+ * HW timer registers (TIMER0 - TIMER3), which are closely related to the
+ * next beacon target time (NBTT), and that the HW updates these timers
+ * seperately based on the current TSF value. The hardware increments each
+ * timer by the beacon interval, when the local TSF coverted to TU is equal
+ * to the value stored in the timer.
+ *
+ * The reception of a beacon with the same BSSID can update the local HW TSF
+ * at any time - this is something we can't avoid. If the TSF jumps to a
+ * time which is later than the time stored in a timer, this timer will not
+ * be updated until the TSF in TU wraps around at 16 bit (the size of the
+ * timers) and reaches the time which is stored in the timer.
+ *
+ * The problem is that these timers are closely related to TIMER0 (NBTT) and
+ * that they define a time "window". When the TSF jumps between two timers
+ * (e.g. ATIM and NBTT), the one in the past will be left behind (not
+ * updated), while the one in the future will be updated every beacon
+ * interval. This causes the window to get larger, until the TSF wraps
+ * around as described above and the timer which was left behind gets
+ * updated again. But - because the beacon interval is usually not an exact
+ * divisor of the size of the timers (16 bit), an unwanted "window" between
+ * these timers has developed!
+ *
+ * This is especially important with the ATIM window, because during
+ * the ATIM window only ATIM frames and no data frames are allowed to be
+ * sent, which creates transmission pauses after each beacon. This symptom
+ * has been described as "ramping ping" because ping times increase linearly
+ * for some time and then drop down again. A wrong window on the DMA beacon
+ * timer has the same effect, so we check for these two conditions.
+ *
+ * Returns true if O.K.
+ */
+bool
+ath5k_hw_check_beacon_timers(struct ath5k_hw *ah, int intval)
+{
+        unsigned int nbtt, atim, dma;
+
+        nbtt = ath5k_hw_reg_read(ah, AR5K_TIMER0);
+        atim = ath5k_hw_reg_read(ah, AR5K_TIMER3);
+        dma = ath5k_hw_reg_read(ah, AR5K_TIMER1) >> 3;
+
+        /* NOTE: SWBA is different. Having a wrong window there does not
+         * stop us from sending data and this condition is catched thru
+         * other means (SWBA interrupt) */
+
+        if (ath5k_check_timer_win(nbtt, atim, 1, intval) &&
+            ath5k_check_timer_win(dma, nbtt, AR5K_TUNE_DMA_BEACON_RESP,
+                                  intval))
+                return true; /* O.K. */
+        return false;
+}
+
+/**
  * ath5k_hw_set_coverage_class - Set IEEE 802.11 coverage class
  *
  * @ah: The &struct ath5k_hw