From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965710AbYEBP4l (ORCPT ); Fri, 2 May 2008 11:56:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965005AbYEBPv7 (ORCPT ); Fri, 2 May 2008 11:51:59 -0400 Received: from opensource.wolfsonmicro.com ([80.75.67.52]:38988 "EHLO opensource2.wolfsonmicro.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1765698AbYEBPvx (ORCPT ); Fri, 2 May 2008 11:51:53 -0400 Subject: [PATCH 12/13] regulator: documentation - machine From: Liam Girdwood To: Andrew Morton Cc: linux-kernel , arm kernel , Mark Brown Content-Type: text/plain Date: Fri, 02 May 2008 16:44:17 +0100 Message-Id: <1209743057.12502.56.camel@odin> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This adds documentation describing the regulator machine interface. Signed-off-by: Liam Girdwood --- Documentation/power/regulator/machine.txt | 101 +++++++++++++++++++++++++++++ 1 files changed, 101 insertions(+), 0 deletions(-) create mode 100644 Documentation/power/regulator/machine.txt diff --git a/Documentation/power/regulator/machine.txt b/Documentation/power/regulator/machine.txt new file mode 100644 index 0000000..c9a3566 --- /dev/null +++ b/Documentation/power/regulator/machine.txt @@ -0,0 +1,101 @@ +Regulator Machine Driver Interface +=================================== + +The regulator machine driver interface is intended for board/machine specific +initialisation code to configure the regulator subsystem. Typical things that +machine drivers would do are :- + + 1. Regulator -> Device mapping. + 2. Regulator supply configuration. + 3. Power Domain constraint setting. + + + +1. Regulator -> device mapping +============================== +Consider the following machine :- + + Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V] + | + +-> [Consumer B @ 3.3V] + +The drivers for consumers A & B must be mapped to the correct regulator in +order to control their power supply. This mapping can be achieved in machine +initialisation code by calling :- + +int regulator_set_device_supply(const char *regulator, struct device *dev, + const char *supply); + +and is shown with the following code :- + +regulator_set_device_supply("Regulator-1", devB, "Vcc"); +regulator_set_device_supply("Regulator-2", devA, "Vcc"); + +This maps Regulator-1 to the 'Vcc' supply for Consumer B and maps Regulator-2 +to the 'Vcc' supply for Consumer A. + + +2. Regulator supply configuration. +================================== +Consider the following machine (again) :- + + Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V] + | + +-> [Consumer B @ 3.3V] + +Regulator-1 supplies power to Regulator-2. This relationship must be registered +with the core so that Regulator-1 is also enabled when Consumer A enables it's +supply (Regulator-2). + +This relationship can be register with the core via :- + +int regulator_set_supply(const char *regulator, const char *regulator_supply); + +In this example we would use the following code :- + +regulator_set_supply("Regulator-2", "Regulator-1"); + +Relationships can be queried by calling :- + +const char *regulator_get_supply(const char *regulator); + + +3. Power Domain constraint setting. +=================================== +Each power domain within a system has physical constraints on voltage and +current. This must be defined in software so that the power domain is always +operated within specifications. + +Consider the following machine (again) :- + + Regulator-1 -+-> Regulator-2 --> [Consumer A @ 1.8 - 2.0V] + | + +-> [Consumer B @ 3.3V] + +This gives us two regulators and two power domains: + + Domain 1: Regulator-2, Consumer B. + Domain 2: Consumer A. + +Constraints can be registered by calling :- + +int regulator_set_platform_constraints(const char *regulator, + struct regulation_constraints *constraints); + +The example is defined as follows :- + +struct regulation_constraints domain_1 = { + .min_uV = 3300000, + .max_uV = 3300000, + .valid_modes_mask = REGULATOR_MODE_NORMAL, +}; + +struct regulation_constraints domain_2 = { + .min_uV = 1800000, + .max_uV = 2000000, + .valid_ops_mask = REGULATOR_CHANGE_VOLTAGE, + .valid_modes_mask = REGULATOR_MODE_NORMAL, +}; + +regulator_set_platform_constraints("Regulator-1", &domain_1); +regulator_set_platform_constraints("Regulator-2", &domain_2); -- 1.5.4.3