linux-kernel - [PATCH V1 21/26] DT bindings: spi: add tx/rx clock delay SPI client properties

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Date:   Tue, 26 Mar 2019 22:56:42 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <talho@...dia.com>, <skomatineni@...dia.com>, <broonie@...nel.org>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <kyarlagadda@...dia.com>
CC:     <ldewangan@...dia.com>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <devicetree@...r.kernel.org>
Subject: [PATCH V1 21/26] DT bindings: spi: add tx/rx clock delay SPI client properties

This patch adds Tegra SPI master tx and rx clock delay properties.

TX/RX clock delays may vary depending on the platform design trace lengths
for each client on the Tegra SPI bus. These properties helps to tune the
clock delays.

Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
---
 .../devicetree/bindings/spi/nvidia,tegra114-spi.txt      | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra114-spi.txt b/Documentation/devicetree/bindings/spi/nvidia,tegra114-spi.txt
index 6167c5234b64..2b84b7b726ce 100644
--- a/Documentation/devicetree/bindings/spi/nvidia,tegra114-spi.txt
+++ b/Documentation/devicetree/bindings/spi/nvidia,tegra114-spi.txt
@@ -29,6 +29,12 @@ spi-client device controller properties:
 - nvidia,cs-hold-clk-count: CS hold timing parameter.
 - nvidia,cs-inactive-cycles: CS inactive delay in terms of clock between
   transfers.
+- nvidia,tx-clk-tap-delay: Delays the clock going out to the external device
+  with this tap value. This property is used to tune the outgoing data from
+  Tegra SPI master with respect to outgoing Tegra SPI master clock.
+- nvidia,rx-clk-tap-delay: Delays the clock coming in from the external device
+  with this tap value. This property is used to adjust the Tegra SPI master
+  clock with respect to the data from the SPI slave device.
 
 Example:
 
@@ -45,4 +51,14 @@ spi@...0d600 {
 	reset-names = "spi";
 	dmas = <&apbdma 16>, <&apbdma 16>;
 	dma-names = "rx", "tx";
+
+	<spi-client>@<bus_num> {
+		...
+		...
+		nvidia,cs-setup-clk-count = <10>;
+		nvidia,cs-hold-clk-count = <10>;
+		nvidia,rx-clk-tap-delay = <0>;
+		nvidia,tx-clk-tap-delay = <16>;
+		...
+	};
 };
-- 
2.7.4