diff options
Diffstat (limited to 'drivers/spi/spi.c')
| -rw-r--r-- | drivers/spi/spi.c | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index c725b4bab7af..9036d7a50674 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -3622,6 +3622,55 @@ int spi_split_transfers_maxsize(struct spi_controller *ctlr, } EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize); + +/** + * spi_split_transfers_maxwords - split spi transfers into multiple transfers + * when an individual transfer exceeds a + * certain number of SPI words + * @ctlr: the @spi_controller for this transfer + * @msg: the @spi_message to transform + * @maxwords: the number of words to limit each transfer to + * @gfp: GFP allocation flags + * + * Return: status of transformation + */ +int spi_split_transfers_maxwords(struct spi_controller *ctlr, + struct spi_message *msg, + size_t maxwords, + gfp_t gfp) +{ + struct spi_transfer *xfer; + + /* + * 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 + * potentially belong to a different list by the time the + * replacement has happened). + */ + list_for_each_entry(xfer, &msg->transfers, transfer_list) { + size_t maxsize; + int ret; + + if (xfer->bits_per_word <= 8) + maxsize = maxwords; + else if (xfer->bits_per_word <= 16) + maxsize = 2 * maxwords; + else + maxsize = 4 * maxwords; + + if (xfer->len > maxsize) { + ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer, + maxsize, gfp); + if (ret) + return ret; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(spi_split_transfers_maxwords); + /*-------------------------------------------------------------------------*/ /* Core methods for SPI controller protocol drivers. Some of the |