spi/pl022: strengthen FIFO watermark level checks

The platform configuration can select custom FIFO watermarks, but
these may conflict the actual FIFO size of the PL022 variant if
set too high. So strengthen the sanity checks to deny any
conflicting settings.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-pl022.c

@@ -1678,17 +1678,57 @@ static int verify_controller_parameters(struct pl022 *pl022,
 			"Communication mode is configured incorrectly\n");
 		return -EINVAL;
 	}
-	if ((chip_info->rx_lev_trig < SSP_RX_1_OR_MORE_ELEM)
-	    || (chip_info->rx_lev_trig > SSP_RX_32_OR_MORE_ELEM)) {
+	switch (chip_info->rx_lev_trig) {
+	case SSP_RX_1_OR_MORE_ELEM:
+	case SSP_RX_4_OR_MORE_ELEM:
+	case SSP_RX_8_OR_MORE_ELEM:
+		/* These are always OK, all variants can handle this */
+		break;
+	case SSP_RX_16_OR_MORE_ELEM:
+		if (pl022->vendor->fifodepth < 16) {
+			dev_err(&pl022->adev->dev,
+			"RX FIFO Trigger Level is configured incorrectly\n");
+			return -EINVAL;
+		}
+		break;
+	case SSP_RX_32_OR_MORE_ELEM:
+		if (pl022->vendor->fifodepth < 32) {
+			dev_err(&pl022->adev->dev,
+			"RX FIFO Trigger Level is configured incorrectly\n");
+			return -EINVAL;
+		}
+		break;
+	default:
 		dev_err(&pl022->adev->dev,
 			"RX FIFO Trigger Level is configured incorrectly\n");
 		return -EINVAL;
+		break;
 	}
-	if ((chip_info->tx_lev_trig < SSP_TX_1_OR_MORE_EMPTY_LOC)
-	    || (chip_info->tx_lev_trig > SSP_TX_32_OR_MORE_EMPTY_LOC)) {
+	switch (chip_info->tx_lev_trig) {
+	case SSP_TX_1_OR_MORE_EMPTY_LOC:
+	case SSP_TX_4_OR_MORE_EMPTY_LOC:
+	case SSP_TX_8_OR_MORE_EMPTY_LOC:
+		/* These are always OK, all variants can handle this */
+		break;
+	case SSP_TX_16_OR_MORE_EMPTY_LOC:
+		if (pl022->vendor->fifodepth < 16) {
+			dev_err(&pl022->adev->dev,
+			"TX FIFO Trigger Level is configured incorrectly\n");
+			return -EINVAL;
+		}
+		break;
+	case SSP_TX_32_OR_MORE_EMPTY_LOC:
+		if (pl022->vendor->fifodepth < 32) {
+			dev_err(&pl022->adev->dev,
+			"TX FIFO Trigger Level is configured incorrectly\n");
+			return -EINVAL;
+		}
+		break;
+	default:
 		dev_err(&pl022->adev->dev,
 			"TX FIFO Trigger Level is configured incorrectly\n");
 		return -EINVAL;
+		break;
 	}
 	if (chip_info->iface == SSP_INTERFACE_NATIONAL_MICROWIRE) {
 		if ((chip_info->ctrl_len < SSP_BITS_4)