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Subject[PATCH 01/20] Blackfin SPI Driver: ensure cache coherency before doing DMA
Date
From: Vitja Makarov <vitja.makarov@gmail.com>

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>
---
drivers/spi/spi_bfin5xx.c | 23 ++++++++++++++++++++---
1 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 7fea3cf..590f975 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);
--
1.5.6.3

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