linux-kernel - [PATCH v7 1/2] pwm: sifive: Add DT documentation for SiFive PWM Controller

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Message-Id: <1550740301-10097-2-git-send-email-yash.shah@sifive.com>
Date:   Thu, 21 Feb 2019 14:41:40 +0530
From:   Yash Shah <yash.shah@...ive.com>
To:     palmer@...ive.com, linux-pwm@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Cc:     thierry.reding@...il.com, robh+dt@...nel.org, mark.rutland@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        sachin.ghadi@...ive.com, paul.walmsley@...ive.com,
        Yash Shah <yash.shah@...ive.com>
Subject: [PATCH v7 1/2] pwm: sifive: Add DT documentation for SiFive PWM Controller

DT documentation for PWM controller added.

Signed-off-by: Wesley W. Terpstra <wesley@...ive.com>
[Atish: Compatible string update]
Signed-off-by: Atish Patra <atish.patra@....com>
Signed-off-by: Yash Shah <yash.shah@...ive.com>
---
 .../devicetree/bindings/pwm/pwm-sifive.txt         | 33 ++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sifive.txt

diff --git a/Documentation/devicetree/bindings/pwm/pwm-sifive.txt b/Documentation/devicetree/bindings/pwm/pwm-sifive.txt
new file mode 100644
index 0000000..36447e3
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-sifive.txt
@@ -0,0 +1,33 @@
+SiFive PWM controller
+
+Unlike most other PWM controllers, the SiFive PWM controller currently only
+supports one period for all channels in the PWM. All PWMs need to run at
+the same period. The period also has significant restrictions on the values
+it can achieve, which the driver rounds to the nearest achievable period.
+PWM RTL that corresponds to the IP block version numbers can be found
+here:
+
+https://github.com/sifive/sifive-blocks/tree/master/src/main/scala/devices/pwm
+
+Required properties:
+- compatible: Should be "sifive,<chip>-pwm" and "sifive,pwm<version>".
+  Supported compatible strings are: "sifive,fu540-c000-pwm" for the SiFive
+  PWM v0 as integrated onto the SiFive FU540 chip, and "sifive,pwm0" for the
+  SiFive PWM v0 IP block with no chip integration tweaks.
+  Please refer to sifive-blocks-ip-versioning.txt for details.
+- reg: physical base address and length of the controller's registers
+- clocks: Should contain a clock identifier for the PWM's parent clock.
+- #pwm-cells: Should be 3. See pwm.txt in this directory
+  for a description of the cell format.
+- interrupts: one interrupt per PWM channel
+
+Examples:
+
+pwm:  pwm@...20000 {
+	compatible = "sifive,fu540-c000-pwm", "sifive,pwm0";
+	reg = <0x0 0x10020000 0x0 0x1000>;
+	clocks = <&tlclk>;
+	interrupt-parent = <&plic>;
+	interrupts = <42 43 44 45>;
+	#pwm-cells = <3>;
+};
-- 
1.9.1