spi: topcliff-pch: Use core message validation

The topcliff-pch driver requires TX and RX buffers on all transfers, open
coding checks for this. Remove those open coded checks and instead rely on
the core functionality, which has the added bonus that it will fix up any
transfers submitted by drivers as needed rather than erroring out.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220615174138.4060912-1-broonie@kernel.org

drivers/spi/spi-topcliff-pch.c

@@ -455,35 +455,10 @@ static void pch_spi_reset(struct spi_master *master)
 
 static int pch_spi_transfer(struct spi_device *pspi, struct spi_message *pmsg)
 {
-
-	struct spi_transfer *transfer;
 	struct pch_spi_data *data = spi_master_get_devdata(pspi->master);
 	int retval;
 	unsigned long flags;
 
-	spin_lock_irqsave(&data->lock, flags);
-	/* validate Tx/Rx buffers and Transfer length */
-	list_for_each_entry(transfer, &pmsg->transfers, transfer_list) {
-		if (!transfer->tx_buf && !transfer->rx_buf) {
-			dev_err(&pspi->dev,
-				"%s Tx and Rx buffer NULL\n", __func__);
-			retval = -EINVAL;
-			goto err_return_spinlock;
-		}
-
-		if (!transfer->len) {
-			dev_err(&pspi->dev, "%s Transfer length invalid\n",
-				__func__);
-			retval = -EINVAL;
-			goto err_return_spinlock;
-		}
-
-		dev_dbg(&pspi->dev,
-			"%s Tx/Rx buffer valid. Transfer length valid\n",
-			__func__);
-	}
-	spin_unlock_irqrestore(&data->lock, flags);
-
 	/* We won't process any messages if we have been asked to terminate */
 	if (data->status == STATUS_EXITING) {
 		dev_err(&pspi->dev, "%s status = STATUS_EXITING.\n", __func__);
@@ -518,10 +493,6 @@ static int pch_spi_transfer(struct spi_device *pspi, struct spi_message *pmsg)
 err_out:
 	dev_dbg(&pspi->dev, "%s RETURN=%d\n", __func__, retval);
 	return retval;
-err_return_spinlock:
-	dev_dbg(&pspi->dev, "%s RETURN=%d\n", __func__, retval);
-	spin_unlock_irqrestore(&data->lock, flags);
-	return retval;
 }
 
 static inline void pch_spi_select_chip(struct pch_spi_data *data,
@@ -1365,6 +1336,7 @@ static int pch_spi_pd_probe(struct platform_device *plat_dev)
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST;
 	master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 	master->max_speed_hz = PCH_MAX_BAUDRATE;
+	master->flags = SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX;
 
 	data->board_dat = board_dat;
 	data->plat_dev = plat_dev;