From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752725Ab1E0Exo (ORCPT ); Fri, 27 May 2011 00:53:44 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:16786 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750794Ab1E0ExX (ORCPT ); Fri, 27 May 2011 00:53:23 -0400 X-AuditID: cbfee61a-b7ce2ae000001a8f-88-4ddf2e3c3a7c Date: Fri, 27 May 2011 13:53:14 +0900 From: MyungJoo Ham Subject: [PATCH v3 2/3] PM / DEVFREQ: add example governors In-reply-to: <1306471995-4048-1-git-send-email-myungjoo.ham@samsung.com> To: linux-pm@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, Len Brown , Pavel Machek , "Rafael J. Wysocki" , Greg Kroah-Hartman , Kyungmin Park , Jiejing Zhang , Colin Cross , Nishanth Menon , Thomas Gleixner , myungjoo.ham@gmail.com Message-id: <1306471995-4048-2-git-send-email-myungjoo.ham@samsung.com> X-Mailer: git-send-email 1.7.4.1 Content-transfer-encoding: 7BIT References: <1306471995-4048-1-git-send-email-myungjoo.ham@samsung.com> X-OriginalArrivalTime: 27 May 2011 04:53:14.0989 (UTC) FILETIME=[FCF281D0:01CC1C29] X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Three CPUFREQ-like governors are provided as examples. powersave: use the lowest frequency possible. The user (device) should set the polling_ms as 0 because polling is useless for this governor. performance: use the highest freqeuncy possible. The user (device) should set the polling_ms as 0 because polling is useless for this governor. simple_ondemand: simplified version of CPUFREQ's ONDEMAND governor. When a user updates OPP entries (enable/disable/add), OPP framework automatically notifies DEVFREQ to update operating frequency accordingly. Thus, DEVFREQ users (device drivers) do not need to update DEVFREQ manually with OPP entry updates or set polling_ms for powersave , performance, or any other "static" governors. Signed-off-by: MyungJoo Ham Signed-off-by: Kyungmin Park --- drivers/base/power/devfreq.c | 69 ++++++++++++++++++++++++++++++++++++++++++ include/linux/devfreq.h | 5 +++ 2 files changed, 74 insertions(+), 0 deletions(-) diff --git a/drivers/base/power/devfreq.c b/drivers/base/power/devfreq.c index 883d953..7648a94 100644 --- a/drivers/base/power/devfreq.c +++ b/drivers/base/power/devfreq.c @@ -395,3 +395,72 @@ static int __init devfreq_init(void) return 0; } late_initcall(devfreq_init); + +static int devfreq_powersave_func(struct devfreq *df, + unsigned long *freq) +{ + *freq = 0; /* devfreq_do will run "ceiling" to 0 */ + return 0; +} + +struct devfreq_governor devfreq_powersave = { + .get_target_freq = devfreq_powersave_func, +}; + +static int devfreq_performance_func(struct devfreq *df, + unsigned long *freq) +{ + *freq = UINT_MAX; /* devfreq_do will run "floor" */ + return 0; +} + +struct devfreq_governor devfreq_performance = { + .get_target_freq = devfreq_performance_func, +}; + +/* Constants for DevFreq-Simple-Ondemand (DFSO) */ +#define DFSO_UPTHRESHOLD (90) +#define DFSO_DOWNDIFFERENCTIAL (5) +static int devfreq_simple_ondemand_func(struct devfreq *df, + unsigned long *freq) +{ + struct devfreq_dev_status stat; + int err = df->profile->get_dev_status(df->dev, &stat); + unsigned long long a, b; + + if (err) + return err; + + /* Set MAX if it's busy enough */ + if (stat.busy_time * 100 > + stat.total_time * DFSO_UPTHRESHOLD) { + *freq = UINT_MAX; + return 0; + } + + /* Set MAX if we do not know the initial frequency */ + if (stat.current_frequency == 0) { + *freq = UINT_MAX; + return 0; + } + + /* Keep the current frequency */ + if (stat.busy_time * 100 > + stat.total_time * (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL)) { + *freq = stat.current_frequency; + return 0; + } + + /* Set the desired frequency based on the load */ + a = (unsigned long long) stat.busy_time * stat.current_frequency; + b = div_u64(a, stat.total_time); + b *= 100; + b = div_u64(b, (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL / 2)); + *freq = (unsigned long) b; + + return 0; +} + +struct devfreq_governor devfreq_simple_ondemand = { + .get_target_freq = devfreq_simple_ondemand_func, +}; diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index 59c8bda..1ec9a40 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h @@ -81,6 +81,11 @@ extern int devfreq_add_device(struct device *dev, extern int devfreq_remove_device(struct device *dev); extern int devfreq_update(struct device *dev); extern int devfreq_tickle_device(struct device *dev, unsigned long duration_ms); + +extern struct devfreq_governor devfreq_powersave; +extern struct devfreq_governor devfreq_performance; +extern struct devfreq_governor devfreq_simple_ondemand; + #else /* !CONFIG_PM_DEVFREQ */ static int devfreq_add_device(struct device *dev, struct devfreq_dev_profile *profile, -- 1.7.4.1