Blackfin SPI Driver: ensure cache coherency before doing DMA

Flush or invalidate caches before doing DMA transfer, if needed.

[Mike Frysinger <vapier.adi@gmail.com>: add comment to address the
issue "Full duplex only works for non-DMA transfers".]
Signed-off-by: Vitja Makarov <vitja.makarov@gmail.com>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 3 deletions

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 3410b0c55ed2..e440718b3209 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -26,6 +26,10 @@
 #include <asm/portmux.h>
 #include <asm/bfin5xx_spi.h>
 
+/* reserved_mem_dcache_on and cache friends */
+#include <asm/cplbinit.h>
+#include <asm/cacheflush.h>
+
 #define DRV_NAME        "bfin-spi"
 #define DRV_AUTHOR      "Bryan Wu, Luke Yang"
 #define DRV_DESC        "Blackfin BF5xx on-chip SPI Controller Driver"
@@ -738,9 +742,10 @@ static void pump_transfers(unsigned long data)
                 width, transfer->len);
 
         /*
-         * Try to map dma buffer and do a dma transfer if
-         * successful use different way to r/w according to
-         * drv_data->cur_chip->enable_dma
+         * Try to map dma buffer and do a dma transfer.  If successful use,
+         * different way to r/w according to the enable_dma settings and if
+         * we are not doing a full duplex transfer (since the hardware does
+         * not support full duplex DMA transfers).
          */
         if (!full_duplex && drv_data->cur_chip->enable_dma
                                 && drv_data->len > 6) {
@@ -795,6 +800,12 @@ static void pump_transfers(unsigned long data)
                         /* set transfer mode, and enable SPI */
                         dev_dbg(&drv_data->pdev->dev, "doing DMA in.\n");
 
+                        /* invalidate caches, if needed */
+                        if (bfin_addr_dcachable((unsigned long) drv_data->rx))
+                                invalidate_dcache_range((unsigned long) drv_data->rx,
+                                                        (unsigned long) (drv_data->rx +
+                                                        drv_data->len));
+
                         /* clear tx reg soformer data is not shifted out */
                         write_TDBR(drv_data, 0xFFFF);
 
@@ -815,6 +826,12 @@ static void pump_transfers(unsigned long data)
                 } else if (drv_data->tx != NULL) {
                         dev_dbg(&drv_data->pdev->dev, "doing DMA out.\n");
 
+                        /* flush caches, if needed */
+                        if (bfin_addr_dcachable((unsigned long) drv_data->tx))
+                                flush_dcache_range((unsigned long) drv_data->tx,
+                                                (unsigned long) (drv_data->tx +
+                                                drv_data->len));
+
                         /* start dma */
                         dma_enable_irq(drv_data->dma_channel);
                         dma_config = (RESTART | dma_width | DI_EN);