From patchwork Fri Jan 12 14:22:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Claudiu Beznea X-Patchwork-Id: 859945 Return-Path: X-Original-To: incoming-dt@patchwork.ozlabs.org Delivered-To: patchwork-incoming-dt@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=devicetree-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3zJ4kY4B71z9t3x for ; Sat, 13 Jan 2018 01:24:21 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934234AbeALOYS (ORCPT ); Fri, 12 Jan 2018 09:24:18 -0500 Received: from esa2.microchip.iphmx.com ([68.232.149.84]:45428 "EHLO esa2.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933687AbeALOYQ (ORCPT ); Fri, 12 Jan 2018 09:24:16 -0500 X-IronPort-AV: E=Sophos;i="5.46,349,1511852400"; d="scan'208";a="10394898" Received: from exsmtp03.microchip.com (HELO email.microchip.com) ([198.175.253.49]) by esa2.microchip.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 12 Jan 2018 07:24:14 -0700 Received: from m18063-ThinkPad-T460p.microchip.com (10.10.76.4) by chn-sv-exch03.mchp-main.com (10.10.76.49) with Microsoft SMTP Server id 14.3.352.0; Fri, 12 Jan 2018 07:24:14 -0700 From: Claudiu Beznea To: , , , , , , , , , CC: , , , , , , , Claudiu Beznea Subject: [PATCH v2 11/16] pwm: add documentation for PWM modes Date: Fri, 12 Jan 2018 16:22:58 +0200 Message-ID: <1515766983-15151-12-git-send-email-claudiu.beznea@microchip.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515766983-15151-1-git-send-email-claudiu.beznea@microchip.com> References: <1515766983-15151-1-git-send-email-claudiu.beznea@microchip.com> MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Add documentation for PWM normal and complementary modes. Signed-off-by: Claudiu Beznea --- Documentation/devicetree/bindings/pwm/pwm.txt | 17 ++++++++++++++-- Documentation/pwm.txt | 29 +++++++++++++++++++++++++-- 2 files changed, 42 insertions(+), 4 deletions(-) diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt index 8556263b8502..fdff25bad1db 100644 --- a/Documentation/devicetree/bindings/pwm/pwm.txt +++ b/Documentation/devicetree/bindings/pwm/pwm.txt @@ -43,8 +43,8 @@ because the name "backlight" would be used as fallback anyway. pwm-specifier typically encodes the chip-relative PWM number and the PWM period in nanoseconds. -Optionally, the pwm-specifier can encode a number of flags (defined in -) in a third cell: +Optionally, the pwm-specifier can encode: +1. a number of flags (defined in ) in a third cell: - PWM_POLARITY_INVERTED: invert the PWM signal polarity Example with optional PWM specifier for inverse polarity @@ -54,6 +54,19 @@ Example with optional PWM specifier for inverse polarity pwm-names = "backlight"; }; +2. PWM working modes (defined in ) in the 4th cell: +- PWM_MODE_NORMAL: for all PWM controllers +- PWM_MODE_COMPLEMENTARY: for PWM controllers with more than one output per +PWM channel + +Example with PWM modes: + + bl: blacklight { + pwms = <&pwm 0 5000000 PWM_POLARITY_INVERTED + PWM_DTMODE_NORMAL | PWM_DTMODE_COMPLEMENTARY>; + pwm-names = "backlight"; + }; + 2) PWM controller nodes ----------------------- diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 8fbf0aa3ba2d..58c9bd55f021 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -61,8 +61,8 @@ In addition to the PWM state, the PWM API also exposes PWM arguments, which are the reference PWM config one should use on this PWM. PWM arguments are usually platform-specific and allows the PWM user to only care about dutycycle relatively to the full period (like, duty = 50% of the -period). struct pwm_args contains 2 fields (period and polarity) and should -be used to set the initial PWM config (usually done in the probe function +period). struct pwm_args contains 3 fields (period, polarity and mode) and +should be used to set the initial PWM config (usually done in the probe function of the PWM user). PWM arguments are retrieved with pwm_get_args(). Using PWMs with the sysfs interface @@ -83,6 +83,9 @@ will find: unexport Unexports a PWM channel from sysfs (write-only). + mode + PWM chip supported modes. + The PWM channels are numbered using a per-chip index from 0 to npwm-1. When a PWM channel is exported a pwmX directory will be created in the @@ -110,6 +113,28 @@ channel that was exported. The following properties will then be available: - 0 - disabled - 1 - enabled + mode + Set PWM channel working mode (normal and complementary). PWM chip with + complementary mode could also work in normal mode by using only one physical + output. + + Normal mode - for PWM chips with one output per PWM channel; output + waveforms looks like this: + __ __ __ __ + PWM __| |__| |__| |__| |__ + <--T--> + + Complementary mode - for PWM chips with more than one output per PWM + channel; output waveforms for a PWM controller with 2 outputs per PWM + channel looks line this: + __ __ __ __ + PWMH1 __| |__| |__| |__| |__ + __ __ __ __ __ + PWML1 |__| |__| |__| |__| + <--T--> + + Where T is the signal period. + Implementing a PWM driver -------------------------