Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030249AbbEVUmY (ORCPT ); Fri, 22 May 2015 16:42:24 -0400 Received: from mail-wg0-f42.google.com ([74.125.82.42]:33374 "EHLO mail-wg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757254AbbEVUlf (ORCPT ); Fri, 22 May 2015 16:41:35 -0400 From: Daniel Thompson To: Mike Turquette , Stephen Boyd Cc: Daniel Thompson , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Maxime Coquelin , Kamil Lulko , Andreas Farber , linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, patches@linaro.org, linaro-kernel@lists.linaro.org Subject: [RFC PATCH 1/3] dt-bindings: Document the STM32F4 clock bindings Date: Fri, 22 May 2015 21:41:11 +0100 Message-Id: <1432327273-6810-2-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1432327273-6810-1-git-send-email-daniel.thompson@linaro.org> References: <1432327273-6810-1-git-send-email-daniel.thompson@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2554 Lines: 88 This adds documentation of device tree bindings for the clock related portions of the STM32 RCC block. Signed-off-by: Daniel Thompson --- .../devicetree/bindings/clock/st,stm32-rcc.txt | 65 ++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/st,stm32-rcc.txt diff --git a/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt b/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt new file mode 100644 index 0000000..9715d09 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt @@ -0,0 +1,65 @@ +STMicroelectronics STM32 Reset and Clock Controller +=================================================== + +The RCC IP is both a reset and a clock controller. This documentation only +describes the clock part. + +Please also refer to clock-bindings.txt in this directory for common clock +controller binding usage. + +Required properties: +- compatible: Should be "st,stm32f42xx-rcc" +- reg: should be register base and length as documented in the + datasheet +- #clock-cells: 2, device nodes should specify the clock in their "clocks" + property, containing a phandle to the clock device node, an index selecting + between gated clocks and other clocks and an index specifying the clock to + use. + +Example: + + rcc: rcc@40023800 { + #clock-cells = <2> + compatible = "st,stm32f42xx-rcc", "st,stm32-rcc"; + reg = <0x40023800 0x400>; + }; + +Specifying gated clocks +======================= + +The primary index must be set to 0. + +The secondary index is the bit number within the RCC register bank, starting +from the first RCC clock enable register (RCC_AHB1ENR, address offset 0x30). + +It is calculated as: index = register_offset / 4 * 32 + bit_offset. +Where bit_offset is the bit offset within the register (LSB is 0, MSB is 31). + +Example: + + /* Gated clock, AHB1 bit 0 (GPIOA) */ + ... { + clocks = <&rcc 0 0> + }; + + /* Gated clock, AHB2 bit 4 (GPIOA) */ + ... { + clocks = <&rcc 0 36> + }; + +Specifying other clocks +======================= + +The primary index must be set to 1. + +The secondary index is bound with the following magic numbers: + + 0 SYSTICK + 1 FCLK + +Example: + + /* Misc clock, FCLK */ + ... { + clocks = <&rcc 1 1> + }; -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/