From 1c1a2ccdbdfe35318afdb99d982a10409b1b517a Mon Sep 17 00:00:00 2001
From: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
Date: Thu, 11 Nov 2021 08:00:00 +0100
Subject: [PATCH] dts/bindings: Add a dedicated frame format property on SPI
 device

Most of the time SPI devices use TI's frame format. But some may use
Motorola's. This is already taken care of in the SPI API and now it will
be possible to select the right format from DTS. Like:

    ...
    frame-format = <SPI_FRAME_FORMAT_MOTOROLA>;
    ...

This is only meant to be used for devices supporting both formats (so
the format is not hard-coded in the driver) and selected by hardware
configuration or else.  Which, in such case, it will need to use
DT_INST_PROP(<instance number>, frame-format) macro call to retrieve
the property value. Others can fully ignore it.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
---
 dts/bindings/spi/spi-device.yaml | 14 ++++++++++++++
 include/drivers/spi.h            | 16 ----------------
 include/dt-bindings/spi/spi.h    | 16 ++++++++++++++++
 3 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/dts/bindings/spi/spi-device.yaml b/dts/bindings/spi/spi-device.yaml
index e529ba5c146..c556596375b 100644
--- a/dts/bindings/spi/spi-device.yaml
+++ b/dts/bindings/spi/spi-device.yaml
@@ -29,3 +29,17 @@ properties:
       enum:
         - 0
         - 2048
+    frame-format:
+      type: int
+      default: 0
+      required: false
+      description: |
+        Motorola or TI frame format. By default it's always Motorola's,
+        thus 0 as this is, by far, the most common format.
+        Use the macros not the actual enum value, here is the concordance
+        list (see dt-bindings/spi/spi.h)
+          0     SPI_FRAME_FORMAT_MOTOROLA
+          32768 SPI_FRAME_FORMAT_TI
+      enum:
+        - 0
+        - 32768
diff --git a/include/drivers/spi.h b/include/drivers/spi.h
index befd7e7ce11..43ec41168c8 100644
--- a/include/drivers/spi.h
+++ b/include/drivers/spi.h
@@ -117,22 +117,6 @@ extern "C" {
 #define SPI_CS_ACTIVE_HIGH	BIT(14)
 /** @} */
 
-/**
- * @name SPI Frame Format
- * @{
- *
- * 2 frame formats are exposed: Motorola and TI.
- * The main difference is the behavior of the CS line. In Motorala it stays
- * active the whole transfer. In TI, it's active only one serial clock period
- * prior to actually make the transfer, it is thus inactive during the transfer,
- * which ends when the clocks ends as well.
- * By default, as it is the most commonly used, the Motorola frame format
- * will prevail.
- */
-#define SPI_FRAME_FORMAT_MOTOROLA	(0U << 15)
-#define SPI_FRAME_FORMAT_TI		(1U << 15)
-/** @} */
-
 /**
  * @name SPI MISO lines (if @kconfig{CONFIG_SPI_EXTENDED_MODES} is enabled)
  * @{
diff --git a/include/dt-bindings/spi/spi.h b/include/dt-bindings/spi/spi.h
index 2c3ea9bbbd5..f6854fb62d3 100644
--- a/include/dt-bindings/spi/spi.h
+++ b/include/dt-bindings/spi/spi.h
@@ -24,6 +24,22 @@
 #define SPI_HALF_DUPLEX		(1U << 11)
 /** @} */
 
+/**
+ * @name SPI Frame Format
+ * @{
+ *
+ * 2 frame formats are exposed: Motorola and TI.
+ * The main difference is the behavior of the CS line. In Motorala it stays
+ * active the whole transfer. In TI, it's active only one serial clock period
+ * prior to actually make the transfer, it is thus inactive during the transfer,
+ * which ends when the clocks ends as well.
+ * By default, as it is the most commonly used, the Motorola frame format
+ * will prevail.
+ */
+#define SPI_FRAME_FORMAT_MOTOROLA	(0U << 15)
+#define SPI_FRAME_FORMAT_TI		(1U << 15)
+/** @} */
+
 /**
  * @}
  */