linux-kernel - [PATCH v4 3/6] spi: spi-fsl-dspi: Stub out DMA functions

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Message-Id: <20250627-james-nxp-spi-dma-v4-3-178dba20c120@linaro.org>
Date: Fri, 27 Jun 2025 11:21:39 +0100
From: James Clark <james.clark@...aro.org>
To: Vladimir Oltean <olteanv@...il.com>, Mark Brown <broonie@...nel.org>, 
 Vladimir Oltean <vladimir.oltean@....com>, Arnd Bergmann <arnd@...db.de>, 
 Larisa Grigore <larisa.grigore@....com>, Frank Li <Frank.li@....com>, 
 Christoph Hellwig <hch@....de>
Cc: linux-spi@...r.kernel.org, imx@...ts.linux.dev, 
 linux-kernel@...r.kernel.org, James Clark <james.clark@...aro.org>
Subject: [PATCH v4 3/6] spi: spi-fsl-dspi: Stub out DMA functions

This will allow the build to succeed with !CONFIG_HAS_DMA, either due to
a randconfig build test or when the target only uses one of the non-DMA
transfer modes which this driver supports.

Signed-off-by: James Clark <james.clark@...aro.org>
---
 drivers/spi/spi-fsl-dspi.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 65567745fe9a..feff475dddfc 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -373,6 +373,8 @@ struct fsl_dspi {
 	void (*dev_to_host)(struct fsl_dspi *dspi, u32 rxdata);
 };
 
+static void dspi_setup_accel(struct fsl_dspi *dspi);
+
 static bool is_s32g_dspi(struct fsl_dspi *data)
 {
 	return data->devtype_data == &devtype_data[S32G] ||
@@ -468,6 +470,16 @@ static u32 dspi_pop_tx(struct fsl_dspi *dspi)
 	return txdata;
 }
 
+/* Push one word to the RX buffer from the POPR register (RX FIFO) */
+static void dspi_push_rx(struct fsl_dspi *dspi, u32 rxdata)
+{
+	if (!dspi->rx)
+		return;
+	dspi->dev_to_host(dspi, rxdata);
+}
+
+#if IS_ENABLED(CONFIG_DMA_ENGINE)
+
 /* Prepare one TX FIFO entry (txdata plus cmd) */
 static u32 dspi_pop_tx_pushr(struct fsl_dspi *dspi)
 {
@@ -481,14 +493,6 @@ static u32 dspi_pop_tx_pushr(struct fsl_dspi *dspi)
 	return cmd << 16 | data;
 }
 
-/* Push one word to the RX buffer from the POPR register (RX FIFO) */
-static void dspi_push_rx(struct fsl_dspi *dspi, u32 rxdata)
-{
-	if (!dspi->rx)
-		return;
-	dspi->dev_to_host(dspi, rxdata);
-}
-
 static void dspi_tx_dma_callback(void *arg)
 {
 	struct fsl_dspi *dspi = arg;
@@ -589,8 +593,6 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi *dspi)
 	return 0;
 }
 
-static void dspi_setup_accel(struct fsl_dspi *dspi);
-
 static void dspi_dma_xfer(struct fsl_dspi *dspi)
 {
 	struct spi_message *message = dspi->cur_msg;
@@ -722,6 +724,18 @@ static void dspi_release_dma(struct fsl_dspi *dspi)
 		dma_release_channel(dma->chan_rx);
 	}
 }
+#else
+static void dspi_dma_xfer(struct fsl_dspi *dspi)
+{
+	dspi->cur_msg->status = -EINVAL;
+}
+static int dspi_request_dma(struct fsl_dspi *dspi, phys_addr_t phy_addr)
+{
+	dev_err(&dspi->pdev->dev, "DMA support not enabled in kernel\n");
+	return -EINVAL;
+}
+static void dspi_release_dma(struct fsl_dspi *dspi) {}
+#endif
 
 static void hz_to_spi_baud(char *pbr, char *br, int speed_hz,
 			   unsigned long clkrate, bool mtf_enabled)

-- 
2.34.1