From: Martin Sperl <ker...@martin.sperl.org>
Added spi_master.min_dma_len plus methods requireing this information:
* spi_translate_message_size_align_merge
* spi_can_dma_min_dma_len
Signed-off-by: Martin Sperl <ker...@martin.sperl.org>
---
drivers/spi/spi.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/spi/spi.h | 14 +++++++++-
2 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 020e34d..883bfa8 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -277,6 +277,27 @@ void spi_statistics_add_transfer_stats(struct
spi_statistics *stats,
}
EXPORT_SYMBOL_GPL(spi_statistics_add_transfer_stats);
+/**
+ * spi_can_dma_min_dma_len - default implementation for spi_can_dma
+ * that only checks spi_transfer.len is bigger
+ * spi_master.min_dma_len
+ * @master: the spi_master device
+ * @spi: the spi_device
+ * @tfr: the spi_transfer
+ */
+bool spi_can_dma_min_dma_len(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *tfr)
+{
+ /* we start DMA efforts only on bigger transfers */
+ if (tfr->len < master->min_dma_len)
+ return false;
+
+ /* return OK */
+ return true;
+}
+EXPORT_SYMBOL_GPL(spi_can_dma_min_dma_len);
+
/* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
* and the sysfs version makes coldplug work too.
*/
@@ -2793,6 +2814,51 @@ int spi_merge_transfers(struct spi_master *master,
return 0;
}
EXPORT_SYMBOL_GPL(spi_merge_transfers);
+/*-------------------------------------------------------------------------*/
+
+/**
+ * spi_translate_message_size_align_merge - default spi_message translation
+ * code that takes its parameters
+ * from @spi_master
+ *
+ * @master: the spi_master for which we run this translation
+ * @message: the spi_message which we need to translate
+ *
+ * Returns: status of tranformation
+ */
+int spi_translate_message_size_align_merge(
+ struct spi_master *master, struct spi_message *message)
+{
+ int ret;
+
+ /* translate the message */
+
+ /* fix alignment of transfers by splitting rx_buf/tx_buf
+ * (and worsted case copying tx_buf)
+ */
+ ret = spi_split_transfers_unaligned(master, message,
+ master->min_dma_len,
+ master->dma_alignment,
+ GFP_KERNEL);
+ if (ret)
+ return ret;
+
+ /* limit transfer length */
+ if (master->max_dma_len) {
+ ret = spi_split_transfers_maxsize(master, message,
+ master->max_dma_len,
+ GFP_KERNEL);
+ if (ret)
+ return ret;
+ }
+
+ /* merge spi_transfers up to a full page */
+ ret = spi_merge_transfers(master, message, 2, PAGE_SIZE,
+ GFP_KERNEL);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(spi_translate_message_size_align_merge);
/*-------------------------------------------------------------------------*/
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 4b4c1e9..f055a47 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -351,6 +351,9 @@ static inline void spi_unregister_driver(struct spi_driver
*sdrv)
* while the hardware is prepared, using the parent
* device for the spidev
* @max_dma_len: Maximum length of a DMA transfer for the device.
+ * @min_dma_len: Minimum length of a DMA transfer for the device.
+ * (mostly to avoid dma_mapping a buffer when dma is not used,
+ * should be multiple of dma_alignment)
* @prepare_transfer_hardware: a message will soon arrive from the queue
* so the subsystem requests the driver to prepare the transfer hardware
* by issuing this call
@@ -423,7 +426,6 @@ struct spi_master {
* buffers; let protocol drivers know about these requirements.
*/
u16 dma_alignment;
-
/* spi_device.mode flags understood by this controller driver */
u16 mode_bits;
@@ -517,6 +519,7 @@ struct spi_master {
bool cur_msg_prepared;
bool cur_msg_mapped;
struct completion xfer_completion;
+ size_t min_dma_len;
size_t max_dma_len;
int (*prepare_transfer_hardware)(struct spi_master *master);
@@ -940,6 +943,15 @@ extern struct spi_replaced_transfers
*spi_replace_transfers(
size_t extradatasize,
gfp_t gfp);
+/* some default implementations that drivers may use */
+extern int spi_translate_message_size_align_merge(
+ struct spi_master *master, struct spi_message *message);
+
+/* a default implementation of can_dma */
+extern bool spi_can_dma_min_dma_len(struct spi_master *master,
+ struct spi_device *spi,
+ struct spi_transfer *tfr);
+
/*---------------------------------------------------------------------------*/
/* SPI transfer transformation methods */
--
1.7.10.4
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