b43: Add PIO support for PCMCIA devices

This adds PIO support back (D'oh!) for PCMCIA devices.
This is a complete rewrite of the old PIO code. It does actually work
and we get reasonable performance out of it on a modern machine.
On a PowerBook G4 I get a few MBit for TX and a few more for RX.
So it doesn't work as well as DMA (of course), but it's a _lot_ faster
than the old PIO code (only got a few kBit with that).

The limiting factor is the host CPU speed. So it will generate 100%
CPU usage when the network interface is heavily loaded. A voluntary preemption
point in the RX path makes sure Desktop Latency isn't hurt.

PIO is needed for 16bit PCMCIA devices, as we really don't want to poke with
the braindead DMA mechanisms on PCMCIA sockets. Additionally, not all
PCMCIA sockets do actually support DMA in 16bit mode (mine doesn't).

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/Kconfig

@@ -62,6 +62,13 @@ config B43_PCMCIA
 
 	  If unsure, say N.
 
+# Data transfers to the device via PIO
+# This is only needed on PCMCIA devices. All others can do DMA properly.
+config B43_PIO
+	bool
+	depends on B43 && (B43_PCMCIA || B43_FORCE_PIO)
+	default y
+
 config B43_NPHY
 	bool "Pre IEEE 802.11n support (BROKEN)"
 	depends on B43 && EXPERIMENTAL && BROKEN
@@ -94,3 +101,13 @@ config B43_DEBUG
 
 	  Say Y, if you want to find out why the driver does not
 	  work for you.
+
+config B43_FORCE_PIO
+	bool "Force usage of PIO instead of DMA"
+	depends on B43 && B43_DEBUG
+	---help---
+	  This will disable DMA and always enable PIO instead.
+
+	  Say N!
+	  This is only for debugging the PIO engine code. You do
+	  _NOT_ want to enable this.

drivers/net/wireless/b43/Makefile

@@ -8,6 +8,7 @@ b43-y				+= xmit.o
 b43-y				+= lo.o
 b43-y				+= wa.o
 b43-y				+= dma.o
+b43-$(CONFIG_B43_PIO)		+= pio.o
 b43-$(CONFIG_B43_RFKILL)	+= rfkill.o
 b43-$(CONFIG_B43_LEDS)		+= leds.o
 b43-$(CONFIG_B43_PCMCIA)	+= pcmcia.o

drivers/net/wireless/b43/b43.h

@@ -75,6 +75,23 @@
 #define B43_MMIO_DMA64_BASE4		0x300
 #define B43_MMIO_DMA64_BASE5		0x340
 
+/* PIO on core rev < 11 */
+#define B43_MMIO_PIO_BASE0		0x300
+#define B43_MMIO_PIO_BASE1		0x310
+#define B43_MMIO_PIO_BASE2		0x320
+#define B43_MMIO_PIO_BASE3		0x330
+#define B43_MMIO_PIO_BASE4		0x340
+#define B43_MMIO_PIO_BASE5		0x350
+#define B43_MMIO_PIO_BASE6		0x360
+#define B43_MMIO_PIO_BASE7		0x370
+/* PIO on core rev >= 11 */
+#define B43_MMIO_PIO11_BASE0		0x200
+#define B43_MMIO_PIO11_BASE1		0x240
+#define B43_MMIO_PIO11_BASE2		0x280
+#define B43_MMIO_PIO11_BASE3		0x2C0
+#define B43_MMIO_PIO11_BASE4		0x300
+#define B43_MMIO_PIO11_BASE5		0x340
+
 #define B43_MMIO_PHY_VER		0x3E0
 #define B43_MMIO_PHY_RADIO		0x3E2
 #define B43_MMIO_PHY0			0x3E6
@@ -442,7 +459,6 @@ enum {
 };
 
 struct b43_dmaring;
-struct b43_pioqueue;
 
 /* The firmware file header */
 #define B43_FW_TYPE_UCODE	'u'
@@ -598,6 +614,20 @@ struct b43_dma {
 	struct b43_dmaring *rx_ring;
 };
 
+struct b43_pio_txqueue;
+struct b43_pio_rxqueue;
+
+/* Data structures for PIO transmission, per 80211 core. */
+struct b43_pio {
+	struct b43_pio_txqueue *tx_queue_AC_BK; /* Background */
+	struct b43_pio_txqueue *tx_queue_AC_BE; /* Best Effort */
+	struct b43_pio_txqueue *tx_queue_AC_VI; /* Video */
+	struct b43_pio_txqueue *tx_queue_AC_VO; /* Voice */
+	struct b43_pio_txqueue *tx_queue_mcast; /* Multicast */
+
+	struct b43_pio_rxqueue *rx_queue;
+};
+
 /* Context information for a noise calculation (Link Quality). */
 struct b43_noise_calculation {
 	u8 channel_at_start;
@@ -773,8 +803,15 @@ struct b43_wldev {
 	/* PHY/Radio device. */
 	struct b43_phy phy;
 
-	/* DMA engines. */
-	struct b43_dma dma;
+	union {
+		/* DMA engines. */
+		struct b43_dma dma;
+		/* PIO engines. */
+		struct b43_pio pio;
+	};
+	/* Use b43_using_pio_transfers() to check whether we are using
+	 * DMA or PIO data transfers. */
+	bool __using_pio_transfers;
 
 	/* Various statistics about the physical device. */
 	struct b43_stats stats;
@@ -858,6 +895,22 @@ static inline void b43_write32(struct b43_wldev *dev, u16 offset, u32 value)
 	ssb_write32(dev->dev, offset, value);
 }
 
+static inline bool b43_using_pio_transfers(struct b43_wldev *dev)
+{
+#ifdef CONFIG_B43_PIO
+	return dev->__using_pio_transfers;
+#else
+	return 0;
+#endif
+}
+
+#ifdef CONFIG_B43_FORCE_PIO
+# define B43_FORCE_PIO	1
+#else
+# define B43_FORCE_PIO	0
+#endif
+
+
 /* Message printing */
 void b43info(struct b43_wl *wl, const char *fmt, ...)
     __attribute__ ((format(printf, 2, 3)));

drivers/net/wireless/b43/dma.c

@@ -550,7 +550,6 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring,
 			       struct b43_dmadesc_meta *meta, gfp_t gfp_flags)
 {
 	struct b43_rxhdr_fw4 *rxhdr;
-	struct b43_hwtxstatus *txstat;
 	dma_addr_t dmaaddr;
 	struct sk_buff *skb;
 
@@ -586,8 +585,6 @@ static int setup_rx_descbuffer(struct b43_dmaring *ring,
 
 	rxhdr = (struct b43_rxhdr_fw4 *)(skb->data);
 	rxhdr->frame_len = 0;
-	txstat = (struct b43_hwtxstatus *)(skb->data);
-	txstat->cookie = 0;
 
 	return 0;
 }
@@ -776,6 +773,18 @@ static u64 supported_dma_mask(struct b43_wldev *dev)
 	return DMA_30BIT_MASK;
 }
 
+static enum b43_dmatype dma_mask_to_engine_type(u64 dmamask)
+{
+	if (dmamask == DMA_30BIT_MASK)
+		return B43_DMA_30BIT;
+	if (dmamask == DMA_32BIT_MASK)
+		return B43_DMA_32BIT;
+	if (dmamask == DMA_64BIT_MASK)
+		return B43_DMA_64BIT;
+	B43_WARN_ON(1);
+	return B43_DMA_30BIT;
+}
+
 /* Main initialization function. */
 static
 struct b43_dmaring *b43_setup_dmaring(struct b43_wldev *dev,
@@ -956,7 +965,11 @@ static void b43_destroy_dmaring(struct b43_dmaring *ring,
 
 void b43_dma_free(struct b43_wldev *dev)
 {
-	struct b43_dma *dma = &dev->dma;
+	struct b43_dma *dma;
+
+	if (b43_using_pio_transfers(dev))
+		return;
+	dma = &dev->dma;
 
 	destroy_ring(dma, rx_ring);
 	destroy_ring(dma, tx_ring_AC_BK);
@@ -974,19 +987,7 @@ int b43_dma_init(struct b43_wldev *dev)
 	enum b43_dmatype type;
 
 	dmamask = supported_dma_mask(dev);
-	switch (dmamask) {
-	default:
-		B43_WARN_ON(1);
-	case DMA_30BIT_MASK:
-		type = B43_DMA_30BIT;
-		break;
-	case DMA_32BIT_MASK:
-		type = B43_DMA_32BIT;
-		break;
-	case DMA_64BIT_MASK:
-		type = B43_DMA_64BIT;
-		break;
-	}
+	type = dma_mask_to_engine_type(dmamask);
 	err = ssb_dma_set_mask(dev->dev, dmamask);
 	if (err) {
 		b43err(dev->wl, "The machine/kernel does not support "
@@ -1113,7 +1114,6 @@ static int dma_tx_fragment(struct b43_dmaring *ring,
 	size_t hdrsize = b43_txhdr_size(ring->dev);
 
 #define SLOTS_PER_PACKET  2
-	B43_WARN_ON(skb_shinfo(skb)->nr_frags);
 
 	old_top_slot = ring->current_slot;
 	old_used_slots = ring->used_slots;
@@ -1257,11 +1257,6 @@ int b43_dma_tx(struct b43_wldev *dev,
 	int err = 0;
 	unsigned long flags;
 
-	if (unlikely(skb->len < 2 + 2 + 6)) {
-		/* Too short, this can't be a valid frame. */
-		return -EINVAL;
-	}
-
 	hdr = (struct ieee80211_hdr *)skb->data;
 	if (ctl->flags & IEEE80211_TXCTL_SEND_AFTER_DTIM) {
 		/* The multicast ring will be sent after the DTIM */
@@ -1319,38 +1314,6 @@ int b43_dma_tx(struct b43_wldev *dev,
 	return err;
 }
 
-static void b43_fill_txstatus_report(struct b43_dmaring *ring,
-				    struct ieee80211_tx_status *report,
-				    const struct b43_txstatus *status)
-{
-	bool frame_failed = 0;
-
-	if (status->acked) {
-		/* The frame was ACKed. */
-		report->flags |= IEEE80211_TX_STATUS_ACK;
-	} else {
-		/* The frame was not ACKed... */
-		if (!(report->control.flags & IEEE80211_TXCTL_NO_ACK)) {
-			/* ...but we expected an ACK. */
-			frame_failed = 1;
-			report->excessive_retries = 1;
-		}
-	}
-	if (status->frame_count == 0) {
-		/* The frame was not transmitted at all. */
-		report->retry_count = 0;
-	} else {
-		report->retry_count = status->frame_count - 1;
-#ifdef CONFIG_B43_DEBUG
-		if (frame_failed)
-			ring->nr_failed_tx_packets++;
-		else
-			ring->nr_succeed_tx_packets++;
-		ring->nr_total_packet_tries += status->frame_count;
-#endif /* DEBUG */
-	}
-}
-
 /* Called with IRQs disabled. */
 void b43_dma_handle_txstatus(struct b43_wldev *dev,
 			     const struct b43_txstatus *status)
@@ -1360,6 +1323,7 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
 	struct b43_dmadesc_generic *desc;
 	struct b43_dmadesc_meta *meta;
 	int slot;
+	bool frame_succeed;
 
 	ring = parse_cookie(dev, status->cookie, &slot);
 	if (unlikely(!ring))
@@ -1386,7 +1350,15 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
 			 * status of the transmission.
 			 * Some fields of txstat are already filled in dma_tx().
 			 */
-			b43_fill_txstatus_report(ring, &(meta->txstat), status);
+			frame_succeed = b43_fill_txstatus_report(
+						&(meta->txstat), status);
+#ifdef CONFIG_B43_DEBUG
+			if (frame_succeed)
+				ring->nr_succeed_tx_packets++;
+			else
+				ring->nr_failed_tx_packets++;
+			ring->nr_total_packet_tries += status->frame_count;
+#endif /* DEBUG */
 			ieee80211_tx_status_irqsafe(dev->wl->hw, meta->skb,
 						    &(meta->txstat));
 			/* skb is freed by ieee80211_tx_status_irqsafe() */
@@ -1573,3 +1545,39 @@ void b43_dma_tx_resume(struct b43_wldev *dev)
 	b43_dma_tx_resume_ring(dev->dma.tx_ring_AC_BK);
 	b43_power_saving_ctl_bits(dev, 0);
 }
+
+#ifdef CONFIG_B43_PIO
+static void direct_fifo_rx(struct b43_wldev *dev, enum b43_dmatype type,
+			   u16 mmio_base, bool enable)
+{
+	u32 ctl;
+
+	if (type == B43_DMA_64BIT) {
+		ctl = b43_read32(dev, mmio_base + B43_DMA64_RXCTL);
+		ctl &= ~B43_DMA64_RXDIRECTFIFO;
+		if (enable)
+			ctl |= B43_DMA64_RXDIRECTFIFO;
+		b43_write32(dev, mmio_base + B43_DMA64_RXCTL, ctl);
+	} else {
+		ctl = b43_read32(dev, mmio_base + B43_DMA32_RXCTL);
+		ctl &= ~B43_DMA32_RXDIRECTFIFO;
+		if (enable)
+			ctl |= B43_DMA32_RXDIRECTFIFO;
+		b43_write32(dev, mmio_base + B43_DMA32_RXCTL, ctl);
+	}
+}
+
+/* Enable/Disable Direct FIFO Receive Mode (PIO) on a RX engine.
+ * This is called from PIO code, so DMA structures are not available. */
+void b43_dma_direct_fifo_rx(struct b43_wldev *dev,
+			    unsigned int engine_index, bool enable)
+{
+	enum b43_dmatype type;
+	u16 mmio_base;
+
+	type = dma_mask_to_engine_type(supported_dma_mask(dev));
+
+	mmio_base = b43_dmacontroller_base(type, engine_index);
+	direct_fifo_rx(dev, type, mmio_base, enable);
+}
+#endif /* CONFIG_B43_PIO */

drivers/net/wireless/b43/dma.h

@@ -291,4 +291,7 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
 
 void b43_dma_rx(struct b43_dmaring *ring);
 
+void b43_dma_direct_fifo_rx(struct b43_wldev *dev,
+			    unsigned int engine_index, bool enable);
+
 #endif /* B43_DMA_H_ */