spi: fsi: Batch TX operations

Batch sequential write transfers up to the max TX size (40 bytes).
This controller must specify a max transfer size of only 8 bytes for
RX operations.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://patch.msgid.link/20250131200158.732898-1-eajames@linux.ibm.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index fc9e33be1e0e740098d34be86eb432a189799e4b..e01c63d23b64dd45a0df180df723efaaa2c7ca1c 100644 (file)
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -479,6 +479,19 @@ static int fsi_spi_transfer_one_message(struct spi_controller *ctlr,
 
                                shift = SPI_FSI_SEQUENCE_SHIFT_IN(next->len);
                                fsi_spi_sequence_add(&seq, shift);
+                       } else if (next->tx_buf) {
+                               if ((next->len + transfer->len) > (SPI_FSI_MAX_TX_SIZE + 8)) {
+                                       rc = -EINVAL;
+                                       goto error;
+                               }
+
+                               len = next->len;
+                               while (len > 8) {
+                                       fsi_spi_sequence_add(&seq,
+                                                            SPI_FSI_SEQUENCE_SHIFT_OUT(8));
+                                       len -= 8;
+                               }
+                               fsi_spi_sequence_add(&seq, SPI_FSI_SEQUENCE_SHIFT_OUT(len));
                        } else {
                                next = NULL;
                        }