linux-kernel - [PATCH 09/15] dt: binding: add binding for TZ1090 clock deleter

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Message-Id: <1416438943-11429-10-git-send-email-james.hogan@imgtec.com>
Date:	Wed, 19 Nov 2014 23:15:37 +0000
From:	James Hogan <james.hogan@...tec.com>
To:	Mike Turquette <mturquette@...aro.org>,
	linux-metag@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Cc:	James Hogan <james.hogan@...tec.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>
Subject: [PATCH 09/15] dt: binding: add binding for TZ1090 clock deleter

Add DT binding for the clock deleters in the TZ1090 SoC, which delete up
to 1023 out of every 1024 clock pulses of the input clock.

Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: Mike Turquette <mturquette@...aro.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Pawel Moll <pawel.moll@....com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Ian Campbell <ijc+devicetree@...lion.org.uk>
Cc: Kumar Gala <galak@...eaurora.org>
Cc: linux-metag@...r.kernel.org
Cc: devicetree@...r.kernel.org
---
 .../bindings/clock/img,tz1090-deleter.txt          | 40 ++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/img,tz1090-deleter.txt

diff --git a/Documentation/devicetree/bindings/clock/img,tz1090-deleter.txt b/Documentation/devicetree/bindings/clock/img,tz1090-deleter.txt
new file mode 100644
index 0000000..0f595be
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/img,tz1090-deleter.txt
@@ -0,0 +1,40 @@
+Binding for TZ1090 clock deleter.
+
+This binding uses the common clock binding[1]. The TZ1090 clock deleters can be
+configured to delete a certain fraction of the input clock pulses, so the output
+frequency is:
+
+    deleted_cycles = (reg & bit_mask) >> bit_shift
+    f_out = f_in * (cycle_period - deleted_cycles) / cycle_period
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible         : Shall be "img,tz1090-deleter".
+- #clock-cells       : From common clock binding; shall be set to 0.
+- reg                : Address of configuration register.
+- bit-mask           : Shift of config value field in configuration register.
+- clocks             : From common clock binding.
+
+Required source clocks:
+- 0                  : Reference clock which is deleted to produce the output
+                       clock (doesn't have to be named).
+
+Optional properties:
+- clock-output-names : From common clock binding.
+- bit-shift          : Number of bits to shift the bit-mask, defaults to
+                       (ffs(mask) - 1) if not present.
+- cycle-period       : Period from which clocks are deleted, defaults to
+                       (1 << (fls(mask) - bit-shift)) if not present.
+
+Example:
+	meta_clkdelete {
+		compatible = "img,tz1090-deleter";
+		#clock-cells = <0>;
+		clocks = <&sys_clk_x2_undeleted>;
+		reg = <0x0200591c 0x4>;
+		bit-mask = <0x000003ff>;
+		/* implicit bit-shift = <0> */
+		/* implicit cycle-period = <1024> */
+		clock-output-names = "meta";
+	};
-- 
2.0.4

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