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>

1 files changed, 56 insertions, 3 deletions

diff --git a/drivers/net/wireless/b43/b43.h b/drivers/net/wireless/b43/b43.h
index d40be1568517..ef8ae385835a 100644
--- a/drivers/net/wireless/b43/b43.h
+++ b/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)));