linux-kernel - [PATCH v4 4/9] spi: add multi_lane_mode field to struct spi

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Message-Id: <20251219-spi-add-multi-bus-support-v4-4-145dc5204cd8@baylibre.com>
Date: Fri, 19 Dec 2025 15:32:12 -0600
From: David Lechner <dlechner@...libre.com>
To: Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Marcelo Schmitt <marcelo.schmitt@...log.com>, 
 Michael Hennerich <michael.hennerich@...log.com>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Jonathan Cameron <jic23@...nel.org>, Andy Shevchenko <andy@...nel.org>
Cc: Sean Anderson <sean.anderson@...ux.dev>, linux-spi@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-iio@...r.kernel.org, David Lechner <dlechner@...libre.com>
Subject: [PATCH v4 4/9] spi: add multi_lane_mode field to struct
 spi_transfer

Add a new multi_lane_mode field to struct spi_transfer to allow
peripherals that support multiple SPI lanes to be used with a single
SPI controller.

This requires both the peripheral and the controller to have multiple
serializers connected to separate data lanes. It could also be used with
a single controller and multiple peripherals that are functioning as a
single logical device (similar to parallel memories).

Acked-by: Nuno Sá <nuno.sa@...log.com>
Acked-by: Marcelo Schmitt <marcelo.schmitt@...log.com>
Signed-off-by: David Lechner <dlechner@...libre.com>
---

v4 changes:
* Shortened commit message (useful info will be in docs instead).
* Added whitespace to create clear grouping of macros and the field.

v3 changes:
* Renamed "buses" to "lanes" to reflect devicetree property name change.
---
 include/linux/spi/spi.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 7aff60ab257e..eba7ae8466ac 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -981,6 +981,8 @@ struct spi_res {
  *      (SPI_NBITS_SINGLE) is used.
  * @rx_nbits: number of bits used for reading. If 0 the default
  *      (SPI_NBITS_SINGLE) is used.
+ * @multi_lane_mode: How to serialize data on multiple lanes. One of the
+ *      SPI_MULTI_LANE_MODE_* values.
  * @len: size of rx and tx buffers (in bytes)
  * @speed_hz: Select a speed other than the device default for this
  *      transfer. If 0 the default (from @spi_device) is used.
@@ -1117,6 +1119,12 @@ struct spi_transfer {
 	unsigned	cs_change:1;
 	unsigned	tx_nbits:4;
 	unsigned	rx_nbits:4;
+
+#define SPI_MULTI_LANE_MODE_SINGLE	0 /* only use single lane */
+#define SPI_MULTI_LANE_MODE_STRIPE	1 /* one data word per lane */
+#define SPI_MULTI_LANE_MODE_MIRROR	2 /* same word sent on all lanes */
+	unsigned	multi_lane_mode: 2;
+
 	unsigned	timestamped:1;
 	bool		dtr_mode;
 #define	SPI_NBITS_SINGLE	0x01 /* 1-bit transfer */

-- 
2.43.0