b43legacy: Remove unnecessary MMIO in interrupt hotpath

This removes unnecessary MMIO accesses in the interrupt hotpath. The
patch by Michael Buesch for b43 has been ported to b43legacy.

Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 22 insertions, 56 deletions

diff --git a/drivers/net/wireless/b43legacy/main.c b/drivers/net/wireless/b43legacy/main.c
index 07c7898c87ac..0062b340d989 100644
--- a/drivers/net/wireless/b43legacy/main.c
+++ b/drivers/net/wireless/b43legacy/main.c
@@ -583,35 +583,6 @@ static void b43legacy_short_slot_timing_disable(struct b43legacy_wldev *dev)
         b43legacy_set_slot_time(dev, 20);
 }
 
-/* Enable a Generic IRQ. "mask" is the mask of which IRQs to enable.
- * Returns the _previously_ enabled IRQ mask.
- */
-static inline u32 b43legacy_interrupt_enable(struct b43legacy_wldev *dev,
-                                             u32 mask)
-{
-        u32 old_mask;
-
-        old_mask = b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_MASK);
-        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, old_mask |
-                          mask);
-
-        return old_mask;
-}
-
-/* Disable a Generic IRQ. "mask" is the mask of which IRQs to disable.
- * Returns the _previously_ enabled IRQ mask.
- */
-static inline u32 b43legacy_interrupt_disable(struct b43legacy_wldev *dev,
-                                              u32 mask)
-{
-        u32 old_mask;
-
-        old_mask = b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_MASK);
-        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, old_mask & ~mask);
-
-        return old_mask;
-}
-
 /* Synchronize IRQ top- and bottom-half.
  * IRQs must be masked before calling this.
  * This must not be called with the irq_lock held.
@@ -1200,7 +1171,7 @@ static void handle_irq_beacon(struct b43legacy_wldev *dev)
         /* This is the bottom half of the asynchronous beacon update. */
 
         /* Ignore interrupt in the future. */
-        dev->irq_savedstate &= ~B43legacy_IRQ_BEACON;
+        dev->irq_mask &= ~B43legacy_IRQ_BEACON;
 
         cmd = b43legacy_read32(dev, B43legacy_MMIO_MACCMD);
         beacon0_valid = (cmd & B43legacy_MACCMD_BEACON0_VALID);
@@ -1209,7 +1180,7 @@ static void handle_irq_beacon(struct b43legacy_wldev *dev)
         /* Schedule interrupt manually, if busy. */
         if (beacon0_valid && beacon1_valid) {
                 b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_REASON, B43legacy_IRQ_BEACON);
-                dev->irq_savedstate |= B43legacy_IRQ_BEACON;
+                dev->irq_mask |= B43legacy_IRQ_BEACON;
                 return;
         }
 
@@ -1247,12 +1218,11 @@ static void b43legacy_beacon_update_trigger_work(struct work_struct *work)
         dev = wl->current_dev;
         if (likely(dev && (b43legacy_status(dev) >= B43legacy_STAT_INITIALIZED))) {
                 spin_lock_irq(&wl->irq_lock);
-                /* update beacon right away or defer to irq */
-                dev->irq_savedstate = b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_MASK);
+                /* Update beacon right away or defer to IRQ. */
                 handle_irq_beacon(dev);
                 /* The handler might have updated the IRQ mask. */
                 b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK,
-                            dev->irq_savedstate);
+                                  dev->irq_mask);
                 mmiowb();
                 spin_unlock_irq(&wl->irq_lock);
         }
@@ -1398,7 +1368,7 @@ static void b43legacy_interrupt_tasklet(struct b43legacy_wldev *dev)
         if (reason & B43legacy_IRQ_TX_OK)
                 handle_irq_transmit_status(dev);
 
-        b43legacy_interrupt_enable(dev, dev->irq_savedstate);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, dev->irq_mask);
         mmiowb();
         spin_unlock_irqrestore(&dev->wl->irq_lock, flags);
 }
@@ -1450,18 +1420,18 @@ static irqreturn_t b43legacy_interrupt_handler(int irq, void *dev_id)
         struct b43legacy_wldev *dev = dev_id;
         u32 reason;
 
-        if (!dev)
-                return IRQ_NONE;
+        B43legacy_WARN_ON(!dev);
 
         spin_lock(&dev->wl->irq_lock);
 
-        if (b43legacy_status(dev) < B43legacy_STAT_STARTED)
+        if (unlikely(b43legacy_status(dev) < B43legacy_STAT_STARTED))
+                /* This can only happen on shared IRQ lines. */
                 goto out;
         reason = b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_REASON);
         if (reason == 0xffffffff) /* shared IRQ */
                 goto out;
         ret = IRQ_HANDLED;
-        reason &= b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_MASK);
+        reason &= dev->irq_mask;
         if (!reason)
                 goto out;
 
@@ -1485,10 +1455,9 @@ static irqreturn_t b43legacy_interrupt_handler(int irq, void *dev_id)
                                               & 0x0000DC00;
 
         b43legacy_interrupt_ack(dev, reason);
-        /* disable all IRQs. They are enabled again in the bottom half. */
-        dev->irq_savedstate = b43legacy_interrupt_disable(dev,
-                                                          B43legacy_IRQ_ALL);
-        /* save the reason code and call our bottom half. */
+        /* Disable all IRQs. They are enabled again in the bottom half. */
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0);
+        /* Save the reason code and call our bottom half. */
         dev->irq_reason = reason;
         tasklet_schedule(&dev->isr_tasklet);
 out:
@@ -1948,7 +1917,8 @@ void b43legacy_mac_enable(struct b43legacy_wldev *dev)
 
                 /* Re-enable IRQs. */
                 spin_lock_irq(&dev->wl->irq_lock);
-                b43legacy_interrupt_enable(dev, dev->irq_savedstate);
+                b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK,
+                                  dev->irq_mask);
                 spin_unlock_irq(&dev->wl->irq_lock);
         }
 }
@@ -1967,10 +1937,9 @@ void b43legacy_mac_suspend(struct b43legacy_wldev *dev)
                 /* Mask IRQs before suspending MAC. Otherwise
                  * the MAC stays busy and won't suspend. */
                 spin_lock_irq(&dev->wl->irq_lock);
-                tmp = b43legacy_interrupt_disable(dev, B43legacy_IRQ_ALL);
+                b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0);
                 spin_unlock_irq(&dev->wl->irq_lock);
                 b43legacy_synchronize_irq(dev);
-                dev->irq_savedstate = tmp;
 
                 b43legacy_power_saving_ctl_bits(dev, -1, 1);
                 b43legacy_write32(dev, B43legacy_MMIO_MACCTL,
@@ -2659,7 +2628,6 @@ static int b43legacy_op_dev_config(struct ieee80211_hw *hw,
         int antenna_tx;
         int antenna_rx;
         int err = 0;
-        u32 savedirqs;
 
         antenna_tx = B43legacy_ANTENNA_DEFAULT;
         antenna_rx = B43legacy_ANTENNA_DEFAULT;
@@ -2699,7 +2667,7 @@ static int b43legacy_op_dev_config(struct ieee80211_hw *hw,
                 spin_unlock_irqrestore(&wl->irq_lock, flags);
                 goto out_unlock_mutex;
         }
-        savedirqs = b43legacy_interrupt_disable(dev, B43legacy_IRQ_ALL);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0);
         spin_unlock_irqrestore(&wl->irq_lock, flags);
         b43legacy_synchronize_irq(dev);
 
@@ -2738,7 +2706,7 @@ static int b43legacy_op_dev_config(struct ieee80211_hw *hw,
         }
 
         spin_lock_irqsave(&wl->irq_lock, flags);
-        b43legacy_interrupt_enable(dev, savedirqs);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, dev->irq_mask);
         mmiowb();
         spin_unlock_irqrestore(&wl->irq_lock, flags);
 out_unlock_mutex:
@@ -2801,7 +2769,6 @@ static void b43legacy_op_bss_info_changed(struct ieee80211_hw *hw,
         struct b43legacy_wldev *dev;
         struct b43legacy_phy *phy;
         unsigned long flags;
-        u32 savedirqs;
 
         mutex_lock(&wl->mutex);
         B43legacy_WARN_ON(wl->vif != vif);
@@ -2817,7 +2784,7 @@ static void b43legacy_op_bss_info_changed(struct ieee80211_hw *hw,
                 spin_unlock_irqrestore(&wl->irq_lock, flags);
                 goto out_unlock_mutex;
         }
-        savedirqs = b43legacy_interrupt_disable(dev, B43legacy_IRQ_ALL);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0);
 
         if (changed & BSS_CHANGED_BSSID) {
                 spin_unlock_irqrestore(&wl->irq_lock, flags);
@@ -2862,7 +2829,7 @@ static void b43legacy_op_bss_info_changed(struct ieee80211_hw *hw,
         b43legacy_mac_enable(dev);
 
         spin_lock_irqsave(&wl->irq_lock, flags);
-        b43legacy_interrupt_enable(dev, savedirqs);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, dev->irq_mask);
         /* XXX: why? */
         mmiowb();
         spin_unlock_irqrestore(&wl->irq_lock, flags);
@@ -2922,8 +2889,7 @@ static void b43legacy_wireless_core_stop(struct b43legacy_wldev *dev)
          * setting the status to INITIALIZED, as the interrupt handler
          * won't care about IRQs then. */
         spin_lock_irqsave(&wl->irq_lock, flags);
-        dev->irq_savedstate = b43legacy_interrupt_disable(dev,
-                                                          B43legacy_IRQ_ALL);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0);
         b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_MASK); /* flush */
         spin_unlock_irqrestore(&wl->irq_lock, flags);
         b43legacy_synchronize_irq(dev);
@@ -2963,7 +2929,7 @@ static int b43legacy_wireless_core_start(struct b43legacy_wldev *dev)
 
         /* Start data flow (TX/RX) */
         b43legacy_mac_enable(dev);
-        b43legacy_interrupt_enable(dev, dev->irq_savedstate);
+        b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, dev->irq_mask);
 
         /* Start maintenance work */
         b43legacy_periodic_tasks_setup(dev);
@@ -3126,7 +3092,7 @@ static void setup_struct_wldev_for_init(struct b43legacy_wldev *dev)
         /* IRQ related flags */
         dev->irq_reason = 0;
         memset(dev->dma_reason, 0, sizeof(dev->dma_reason));
-        dev->irq_savedstate = B43legacy_IRQ_MASKTEMPLATE;
+        dev->irq_mask = B43legacy_IRQ_MASKTEMPLATE;
 
         dev->mac_suspended = 1;