5 files changed, 107 insertions, 0 deletions

diff --git a/drivers/spi/spi-offload.c b/drivers/spi/spi-offload.c
index 43582e50e279..df5e963d5ee2 100644
--- a/drivers/spi/spi-offload.c
+++ b/drivers/spi/spi-offload.c
@@ -18,6 +18,7 @@
 
 #include <linux/cleanup.h>
 #include <linux/device.h>
+#include <linux/dmaengine.h>
 #include <linux/export.h>
 #include <linux/kref.h>
 #include <linux/list.h>
@@ -332,6 +333,75 @@ void spi_offload_trigger_disable(struct spi_offload *offload,
 }
 EXPORT_SYMBOL_GPL(spi_offload_trigger_disable);
 
+static void spi_offload_release_dma_chan(void *chan)
+{
+	dma_release_channel(chan);
+}
+
+/**
+ * devm_spi_offload_tx_stream_request_dma_chan - Get the DMA channel info for the TX stream
+ * @dev: Device for devm purposes.
+ * @offload: Offload instance
+ *
+ * This is the DMA channel that will provide data to transfers that use the
+ * %SPI_OFFLOAD_XFER_TX_STREAM offload flag.
+ *
+ * Return: Pointer to DMA channel info, or negative error code
+ */
+struct dma_chan
+*devm_spi_offload_tx_stream_request_dma_chan(struct device *dev,
+					     struct spi_offload *offload)
+{
+	struct dma_chan *chan;
+	int ret;
+
+	if (!offload->ops || !offload->ops->tx_stream_request_dma_chan)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	chan = offload->ops->tx_stream_request_dma_chan(offload);
+	if (IS_ERR(chan))
+		return chan;
+
+	ret = devm_add_action_or_reset(dev, spi_offload_release_dma_chan, chan);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_tx_stream_request_dma_chan);
+
+/**
+ * devm_spi_offload_rx_stream_request_dma_chan - Get the DMA channel info for the RX stream
+ * @dev: Device for devm purposes.
+ * @offload: Offload instance
+ *
+ * This is the DMA channel that will receive data from transfers that use the
+ * %SPI_OFFLOAD_XFER_RX_STREAM offload flag.
+ *
+ * Return: Pointer to DMA channel info, or negative error code
+ */
+struct dma_chan
+*devm_spi_offload_rx_stream_request_dma_chan(struct device *dev,
+					     struct spi_offload *offload)
+{
+	struct dma_chan *chan;
+	int ret;
+
+	if (!offload->ops || !offload->ops->rx_stream_request_dma_chan)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	chan = offload->ops->rx_stream_request_dma_chan(offload);
+	if (IS_ERR(chan))
+		return chan;
+
+	ret = devm_add_action_or_reset(dev, spi_offload_release_dma_chan, chan);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(devm_spi_offload_rx_stream_request_dma_chan);
+
 /* Triggers providers */
 
 static void spi_offload_trigger_unregister(void *data)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a7a4647717d4..10c365e9100a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -31,6 +31,7 @@
 #include <linux/ptp_clock_kernel.h>
 #include <linux/sched/rt.h>
 #include <linux/slab.h>
+#include <linux/spi/offload/types.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi-mem.h>
 #include <uapi/linux/sched/types.h>
@@ -4158,6 +4159,15 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 
 		if (_spi_xfer_word_delay_update(xfer, spi))
 			return -EINVAL;
+
+		/* Make sure controller supports required offload features. */
+		if (xfer->offload_flags) {
+			if (!message->offload)
+				return -EINVAL;
+
+			if (xfer->offload_flags & ~message->offload->xfer_flags)
+				return -EINVAL;
+		}
 	}
 
 	message->status = -EINPROGRESS;
diff --git a/include/linux/spi/offload/consumer.h b/include/linux/spi/offload/consumer.h
index 5a0ec5303d60..cd7d5daa21e6 100644
--- a/include/linux/spi/offload/consumer.h
+++ b/include/linux/spi/offload/consumer.h
@@ -31,4 +31,9 @@ int spi_offload_trigger_enable(struct spi_offload *offload,
 void spi_offload_trigger_disable(struct spi_offload *offload,
 				 struct spi_offload_trigger *trigger);
 
+struct dma_chan *devm_spi_offload_tx_stream_request_dma_chan(struct device *dev,
+							     struct spi_offload *offload);
+struct dma_chan *devm_spi_offload_rx_stream_request_dma_chan(struct device *dev,
+							     struct spi_offload *offload);
+
 #endif /* __LINUX_SPI_OFFLOAD_CONSUMER_H */
diff --git a/include/linux/spi/offload/types.h b/include/linux/spi/offload/types.h
index 7476f2073b02..86d0e8cb9495 100644
--- a/include/linux/spi/offload/types.h
+++ b/include/linux/spi/offload/types.h
@@ -11,6 +11,11 @@
 
 struct device;
 
+/* This is write xfer but TX uses external data stream rather than tx_buf. */
+#define SPI_OFFLOAD_XFER_TX_STREAM	BIT(0)
+/* This is read xfer but RX uses external data stream rather than rx_buf. */
+#define SPI_OFFLOAD_XFER_RX_STREAM	BIT(1)
+
 /* Offload can be triggered by external hardware event. */
 #define SPI_OFFLOAD_CAP_TRIGGER			BIT(0)
 /* Offload can record and then play back TX data when triggered. */
@@ -40,6 +45,8 @@ struct spi_offload {
 	void *priv;
 	/** @ops: callbacks for offload support */
 	const struct spi_offload_ops *ops;
+	/** @xfer_flags: %SPI_OFFLOAD_XFER_* flags supported by provider */
+	u32 xfer_flags;
 };
 
 enum spi_offload_trigger_type {
@@ -75,6 +82,18 @@ struct spi_offload_ops {
 	 * given offload instance.
 	 */
 	void (*trigger_disable)(struct spi_offload *offload);
+	/**
+	 * @tx_stream_request_dma_chan: Optional callback for controllers that
+	 * have an offload where the TX data stream is connected directly to a
+	 * DMA channel.
+	 */
+	struct dma_chan *(*tx_stream_request_dma_chan)(struct spi_offload *offload);
+	/**
+	 * @rx_stream_request_dma_chan: Optional callback for controllers that
+	 * have an offload where the RX data stream is connected directly to a
+	 * DMA channel.
+	 */
+	struct dma_chan *(*rx_stream_request_dma_chan)(struct spi_offload *offload);
 };
 
 #endif /* __LINUX_SPI_OFFLOAD_TYPES_H */
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 98bdc8c16c20..4c087009cf97 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -1093,6 +1093,9 @@ struct spi_transfer {
 
 	u32		effective_speed_hz;
 
+	/* Use %SPI_OFFLOAD_XFER_* from spi-offload.h */
+	unsigned int	offload_flags;
+
 	unsigned int	ptp_sts_word_pre;
 	unsigned int	ptp_sts_word_post;