Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755897Ab1EKQJX (ORCPT ); Wed, 11 May 2011 12:09:23 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:55100 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756941Ab1EKQJU (ORCPT ); Wed, 11 May 2011 12:09:20 -0400 X-AuditID: cbfee61b-b7bb4ae000002c54-b2-4dca41b3d65b Date: Wed, 11 May 2011 16:58:42 +0900 From: MyungJoo Ham Subject: [PATCH v2 2/3] PM / DEVFREQ: add example governors In-reply-to: <1305100723-29161-1-git-send-email-myungjoo.ham@samsung.com> To: linux-pm@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Greg Kroah-Hartman , Mark Brown , Jiejing Zhang , Pavel Machek , Colin Cross , Nishanth Menon , Thomas Gleixner , Len Brown , Kyungmin Park , myungjoo.ham@gmail.com Message-id: <1305100723-29161-2-git-send-email-myungjoo.ham@samsung.com> X-Mailer: git-send-email 1.7.4.1 Content-transfer-encoding: 7BIT References: <1305100723-29161-1-git-send-email-myungjoo.ham@samsung.com> X-OriginalArrivalTime: 11 May 2011 07:58:43.0661 (UTC) FILETIME=[3F8B17D0:01CC0FB1] X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4015 Lines: 125 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 8e2e45b..251d761 100644 --- a/drivers/base/power/devfreq.c +++ b/drivers/base/power/devfreq.c @@ -351,3 +351,72 @@ 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 d08e9f5..ec41ba6 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, bool may_not_exist); 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 -- 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/