From mboxrd@z Thu Jan 1 00:00:00 1970 From: Atish Patra Subject: [RFC 1/4] pwm: sifive: Add DT documentation for SiFive PWM Controller. Date: Tue, 9 Oct 2018 11:51:22 -0700 Message-ID: <1539111085-25502-2-git-send-email-atish.patra@wdc.com> References: <1539111085-25502-1-git-send-email-atish.patra@wdc.com> Return-path: In-Reply-To: <1539111085-25502-1-git-send-email-atish.patra@wdc.com> Sender: linux-kernel-owner@vger.kernel.org To: palmer@sifive.com, linux-riscv@lists.infradead.org, linux-pwm@vger.kernel.org, linux-gpio@vger.kernel.org Cc: linus.walleij@linaro.org, robh+dt@kernel.org, thierry.reding@gmail.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, hch@infradead.org, atish.patra@wdc.com List-Id: devicetree@vger.kernel.org From: "Wesley W. Terpstra" DT documentation for PWM controller added with updated compatible string. Signed-off-by: Wesley W. Terpstra [Atish: Compatible string update] Signed-off-by: Atish Patra --- .../devicetree/bindings/pwm/pwm-sifive.txt | 32 ++++++++++++++++++++++ 1 file changed, 32 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 00000000..532b10fc --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/pwm-sifive.txt @@ -0,0 +1,32 @@ +SiFive PWM controller + +Unlike most other PWM controllers, the SiFive PWM controller currently only +supports one period for all channels in the PWM. This is set globally in DTS. +The period also has significant restrictions on the values it can achieve, +which the driver rounds to the nearest achievable frequency. + +Required properties: +- compatible: should be one of + "sifive,fu540-c000-pwm0","sifive,pwm0". + PWM controller is HiFive Unleashed specific chip which warrants a + specific compatible string. The second string is kept for backward + compatibility until a firmware update with latest compatible string. +- reg: physical base address and length of the controller's registers +- clocks: The frequency the controller runs at +- #pwm-cells: Should be 2. + The first cell is the PWM channel number + The second cell is the PWM polarity +- sifive,approx-period: the driver will get as close to this period as it can +- interrupts: one interrupt per PWM channel (currently unused in the driver) + +Examples: + +pwm: pwm@10020000 { + compatible = "sifive,fu540-c000-pwm0","sifive,pwm0"; + reg = <0x0 0x10020000 0x0 0x1000>; + clocks = <&tlclk>; + interrupt-parent = <&plic>; + interrupts = <42 43 44 45>; + #pwm-cells = <2>; + sifive,approx-period = <1000000>; +}; -- 2.7.4