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spi: core: add spi_split_transfers_maxsize 

Add spi_split_transfers_maxsize method that splits
spi_transfers transparently into multiple transfers
that are below the given max-size.

This makes use of the spi_res framework via
spi_replace_transfers to allocate/free the extra
transfers as well as reverting back the changes applied
while processing the spi_message.

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
hifive-unleashed-5.1
Martin Sperl 2015-12-14 15:20:20 +00:00 committed by Mark Brown
parent 523baf5a06
commit d9f1212272
2 changed files with 126 additions and 0 deletions
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111
drivers/spi/spi.c
View File

@ -144,6 +144,8 @@ SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535");
SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+");
SPI_STATISTICS_SHOW(transfers_split_maxsize, "%lu");
static struct attribute *spi_dev_attrs[] = {
&dev_attr_modalias.attr,
NULL,
@ -181,6 +183,7 @@ static struct attribute *spi_device_statistics_attrs[] = {
&dev_attr_spi_device_transfer_bytes_histo14.attr,
&dev_attr_spi_device_transfer_bytes_histo15.attr,
&dev_attr_spi_device_transfer_bytes_histo16.attr,
&dev_attr_spi_device_transfers_split_maxsize.attr,
NULL,
};
@ -223,6 +226,7 @@ static struct attribute *spi_master_statistics_attrs[] = {
&dev_attr_spi_master_transfer_bytes_histo14.attr,
&dev_attr_spi_master_transfer_bytes_histo15.attr,
&dev_attr_spi_master_transfer_bytes_histo16.attr,
&dev_attr_spi_master_transfers_split_maxsize.attr,
NULL,
};
@ -2237,6 +2241,113 @@ struct spi_replaced_transfers *spi_replace_transfers(
}
EXPORT_SYMBOL_GPL(spi_replace_transfers);
int __spi_split_transfer_maxsize(struct spi_master *master,
struct spi_message *msg,
struct spi_transfer **xferp,
size_t maxsize,
gfp_t gfp)
{
struct spi_transfer *xfer = *xferp, *xfers;
struct spi_replaced_transfers *srt;
size_t offset;
size_t count, i;
/* warn once about this fact that we are splitting a transfer */
dev_warn_once(&msg->spi->dev,
"spi_transfer of length %i exceed max length of %i - needed to split transfers\n",
xfer->len, maxsize);
/* calculate how many we have to replace */
count = DIV_ROUND_UP(xfer->len, maxsize);
/* create replacement */
srt = spi_replace_transfers(msg, xfer, 1, count, NULL, 0, gfp);
if (!srt)
return -ENOMEM;
xfers = srt->inserted_transfers;
/* now handle each of those newly inserted spi_transfers
* note that the replacements spi_transfers all are preset
* to the same values as *xferp, so tx_buf, rx_buf and len
* are all identical (as well as most others)
* so we just have to fix up len and the pointers.
*
* this also includes support for the depreciated
* spi_message.is_dma_mapped interface
*/
/* the first transfer just needs the length modified, so we
* run it outside the loop
*/
xfers[0].len = min(maxsize, xfer[0].len);
/* all the others need rx_buf/tx_buf also set */
for (i = 1, offset = maxsize; i < count; offset += maxsize, i++) {
/* update rx_buf, tx_buf and dma */
if (xfers[i].rx_buf)
xfers[i].rx_buf += offset;
if (xfers[i].rx_dma)
xfers[i].rx_dma += offset;
if (xfers[i].tx_buf)
xfers[i].tx_buf += offset;
if (xfers[i].tx_dma)
xfers[i].tx_dma += offset;
/* update length */
xfers[i].len = min(maxsize, xfers[i].len - offset);
}
/* we set up xferp to the last entry we have inserted,
* so that we skip those already split transfers
*/
*xferp = &xfers[count - 1];
/* increment statistics counters */
SPI_STATISTICS_INCREMENT_FIELD(&master->statistics,
transfers_split_maxsize);
SPI_STATISTICS_INCREMENT_FIELD(&msg->spi->statistics,
transfers_split_maxsize);
return 0;
}
/**
* spi_split_tranfers_maxsize - split spi transfers into multiple transfers
* when an individual transfer exceeds a
* certain size
* @master: the @spi_master for this transfer
* @message: the @spi_message to transform
* @max_size: the maximum when to apply this
*
* Return: status of transformation
*/
int spi_split_transfers_maxsize(struct spi_master *master,
struct spi_message *msg,
size_t maxsize,
gfp_t gfp)
{
struct spi_transfer *xfer;
int ret;
/* iterate over the transfer_list,
* but note that xfer is advanced to the last transfer inserted
* to avoid checking sizes again unnecessarily (also xfer does
* potentiall belong to a different list by the time the
* replacement has happened
*/
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
if (xfer->len > maxsize) {
ret = __spi_split_transfer_maxsize(
master, msg, &xfer, maxsize, gfp);
if (ret)
return ret;
}
}
return 0;
}
EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize);
/*-------------------------------------------------------------------------*/
/* Core methods for SPI master protocol drivers. Some of the

15
include/linux/spi/spi.h
View File

@ -53,6 +53,10 @@ extern struct bus_type spi_bus_type;
*
* @transfer_bytes_histo:
* transfer bytes histogramm
*
* @transfers_split_maxsize:
* number of transfers that have been split because of
* maxsize limit
*/
struct spi_statistics {
spinlock_t lock; /* lock for the whole structure */
@ -72,6 +76,8 @@ struct spi_statistics {
#define SPI_STATISTICS_HISTO_SIZE 17
unsigned long transfer_bytes_histo[SPI_STATISTICS_HISTO_SIZE];
unsigned long transfers_split_maxsize;
};
void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
@ -935,6 +941,15 @@ extern struct spi_replaced_transfers *spi_replace_transfers(
/*---------------------------------------------------------------------------*/
/* SPI transfer transformation methods */
extern int spi_split_transfers_maxsize(struct spi_master *master,
struct spi_message *msg,
size_t maxsize,
gfp_t gfp);
/*---------------------------------------------------------------------------*/
/* All these synchronous SPI transfer routines are utilities layered
* over the core async transfer primitive. Here, "synchronous" means
* they will sleep uninterruptibly until the async transfer completes.