drivers: spi: litex: support SPI_HOLD_ON_CS

support SPI_HOLD_ON_CS.

Signed-off-by: Fin Maaß <f.maass@vogl-electronic.com>

Author: maass-hamburg

drivers/spi/spi_litex_litespi.c

@@ -236,7 +236,9 @@ static int spi_litex_xfer(const struct device *dev, const struct spi_config *con
 		spi_litex_spi_do_rx(dev);
 	} while (spi_context_tx_on(ctx) || spi_context_rx_on(ctx));
 
-	litex_write32(0, dev_config->master_cs_addr);
+	if ((config->operation & SPI_HOLD_ON_CS) == 0) {
+		litex_write32(0, dev_config->master_cs_addr);
+	}
 
 	spi_context_complete(ctx, dev, 0);
 
@@ -305,6 +307,13 @@ static int spi_litex_transceive_async(const struct device *dev,
 static int spi_litex_release(const struct device *dev, const struct spi_config *config)
 {
 	struct spi_litex_data *data = dev->data;
+	const struct spi_litex_dev_config *dev_config = dev->config;
+
+	if (!spi_context_configured(&data->ctx, config)) {
+		return -EINVAL;
+	}
+
+	litex_write32(0, dev_config->master_cs_addr);
 
 	spi_context_unlock_unconditionally(&data->ctx);
 	return 0;
@@ -328,7 +337,9 @@ static void spi_litex_irq_handler(const struct device *dev)
 		} else {
 			litex_write8(0, dev_config->master_ev_enable_addr);
 
-			litex_write32(0, dev_config->master_cs_addr);
+			if ((ctx->config->operation & SPI_HOLD_ON_CS) == 0) {
+				litex_write32(0, dev_config->master_cs_addr);
+			}
 
 			spi_context_complete(ctx, dev, 0);
 		}