Re: [PATCH] opp: introduce library for device-specific OPPs

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Hi Nishanth,

> -----Original Message-----
> From: Menon, Nishanth
> Sent: Thursday, September 16, 2010 8:30 PM
> To: linux-arm; lkml
> Cc: Len Brown; Pavel Machek; Rafael J. Wysocki; Randy Dunlap; Jesse
> Barnes; Matthew Garrett; H. Peter Anvin; Andrew Morton; Benjamin
> Herrenschmidt; Martin K. Petersen; Andi Kleen; linux-pm; linux-doc; linux-
> omap; Menon, Nishanth; Cousson, Benoit; Chikkature Rajashekar,
> Madhusudhan; Phil Carmody; Granados Dorado, Roberto; Shilimkar, Santosh;
> Aguirre, Sergio; Tero Kristo; Eduardo Valentin; Paul Walmsley; Romit
> Dasgupta; Premi, Sanjeev; Gopinath, Thara; Sripathy, Vishwanath; Linus
> Walleij; Kevin Hilman
> Subject: [PATCH] opp: introduce library for device-specific OPPs
>
> SOCs have a standard set of tuples consisting of frequency and
> voltage pairs that the device will support per voltage domain.  These
> are called Operating Performance Points or OPPs. The actual
> definitions of Operating Performance Points varies over silicon within the
> same family of devices. For a specific domain, you can have a set of
> {frequency, voltage} pairs. As the kernel boots and more information
> is available, a set of these are activated based on the precise nature
> of device the kernel boots up on. It is interesting to remember that
> each IP which belongs to a voltage domain may define their own set of
> OPPs on top of this.
>
> To implement an OPP, some sort of power management support is necessary
> hence this library enablement depends on CONFIG_PM, however this does
> not fit into the core power framework as it is an independent library.
> This is hence introduced under lib allowing all architectures to
> selectively enable the feature based on thier capabilities.
>
> Contributions include:
> Sanjeev Premi for the initial concept:
>       http://patchwork.kernel.org/patch/50998/
> Kevin Hilman for converting original design to device-based
> Kevin Hilman and Paul Walmsey for cleaning up many of the function
> abstractions, improvements and data structure handling
> Romit Dasgupta for using enums instead of opp pointers
> Thara Gopinath, Eduardo Valentin and Vishwanath BS for fixes and
> cleanups.
> Linus Walleij for recommending this layer be made generic for usage
> in other architectures beyond OMAP and ARM.
>
> Discussions and comments from:
> http://marc.info/?l=linux-omap&m=126033945313269&w=2
> http://marc.info/?l=linux-omap&m=125482970102327&w=2
> http://marc.info/?t=125809247500002&r=1&w=2
> http://marc.info/?l=linux-omap&m=126025973426007&w=2
> http://marc.info/?t=128152609200064&r=1&w=2
> incorporated.
>
> Cc: Benoit Cousson <b-cousson@xxxxxx>
> Cc: Madhusudhan Chikkature Rajashekar <madhu.cr@xxxxxx>
> Cc: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx>
> Cc: Roberto Granados Dorado <x0095451@xxxxxx>
> Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> Cc: Sergio Alberto Aguirre Rodriguez <saaguirre@xxxxxx>
> Cc: Tero Kristo <Tero.Kristo@xxxxxxxxx>
> Cc: Eduardo Valentin <eduardo.valentin@xxxxxxxxx>
> Cc: Paul Walmsley <paul@xxxxxxxxx>
> Cc: Romit Dasgupta <romit@xxxxxx>
> Cc: Sanjeev Premi <premi@xxxxxx>
> Cc: Thara Gopinath <thara@xxxxxx>
> Cc: Vishwanath BS <vishwanath.bs@xxxxxx>
> Cc: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
>
> Signed-off-by: Nishanth Menon <nm@xxxxxx>
> Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
> ---
> minor notes:
> a) Code rebased to linus's tree commit 03a7ab0
> b) Looping in get-maintainter.pl list and lkml as per thread of discussion
> http://marc.info/?t=128152609200064&r=1&w=2
>
>  Documentation/power/00-INDEX |    2 +
>  include/linux/opp.h          |  136 +++++++++++++
>  kernel/power/Kconfig         |   14 ++
>  lib/Makefile                 |    2 +
>  lib/opp.c                    |  440
> ++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 594 insertions(+), 0 deletions(-)
>  create mode 100644 include/linux/opp.h
>  create mode 100644 lib/opp.c
>
> diff --git a/Documentation/power/00-INDEX b/Documentation/power/00-INDEX
> index fb742c2..45e9d4a 100644
> --- a/Documentation/power/00-INDEX
> +++ b/Documentation/power/00-INDEX
> @@ -14,6 +14,8 @@ interface.txt
>       - Power management user interface in /sys/power
>  notifiers.txt
>       - Registering suspend notifiers in device drivers
> +opp.txt
> +     - Operating Performance Point library
>  pci.txt
>       - How the PCI Subsystem Does Power Management
>  pm_qos_interface.txt
> diff --git a/include/linux/opp.h b/include/linux/opp.h
> new file mode 100644
> index 0000000..94a552b
> --- /dev/null
> +++ b/include/linux/opp.h
> @@ -0,0 +1,136 @@
> +/*
> + * Generic OPP Interface
> + *
> + * Copyright (C) 2009-2010 Texas Instruments Incorporated.
> + *   Nishanth Menon
> + *   Romit Dasgupta <romit@xxxxxx>
> + * Copyright (C) 2009 Deep Root Systems, LLC.
> + *   Kevin Hilman

Just curious why only Romit's e-mail address is there, and not Kevin's or
yours...


> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +#ifndef __ASM_OPP_H
> +#define __ASM_OPP_H
> +
> +#include <linux/err.h>
> +#include <linux/cpufreq.h>
> +
> +/**
> + * struct opp_def - Generic OPP Definition
> + * @freq:    Frequency in hertz corresponding to this OPP
> + * @u_volt:  Nominal voltage in microvolts corresponding to this OPP
> + * @enabled: True/false - is this OPP enabled/disabled by default
> + *
> + * SOCs have a standard set of tuples consisting of frequency and voltage
> + * pairs that the device will support per voltage domain. This is called
> + * Operating Performance Points or OPP. The actual definitions of
> Operating
> + * Performance Points varies over silicon within the same family of
> devices.
> + * For a specific domain, you can have a set of {frequency, voltage}
> pairs
> + * and this is denoted by an array of opp_def. As the kernel boots and
> more
> + * information is available, a set of these are activated based on the
> precise
> + * nature of device the kernel boots up on. It is interesting to remember
> that
> + * each IP which belongs to a voltage domain may define their own set of
> OPPs
> + * on top of this - but this is handled by the appropriate driver.
> + */
> +struct opp_def {
> +     unsigned long freq;
> +     unsigned long u_volt;
> +
> +     bool enabled;
> +};
> +
> +/*
> + * Initialization wrapper used to define an OPP.
> + * To point at the end of a terminator of a list of OPPs,
> + * use OPP_DEF(0, 0, 0)
> + */
> +#define OPP_DEF(_enabled, _freq, _uv)        \
> +{                                            \
> +     .enabled        = _enabled,             \
> +     .freq           = _freq,                \
> +     .u_volt         = _uv,                  \
> +}
> +
> +struct opp;
> +
> +#ifdef CONFIG_PM
> +
> +unsigned long opp_get_voltage(const struct opp *opp);
> +
> +unsigned long opp_get_freq(const struct opp *opp);
> +
> +int opp_get_opp_count(struct device *dev);
> +
> +struct opp *opp_find_freq_exact(struct device *dev, unsigned long freq,
> +                             bool enabled);
> +
> +struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq);
> +
> +struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq);
> +
> +int opp_add(struct device *dev, const struct opp_def *opp_def);
> +
> +int opp_enable(struct opp *opp);
> +
> +int opp_disable(struct opp *opp);
> +
> +void opp_init_cpufreq_table(struct device *dev,
> +                         struct cpufreq_frequency_table **table);
> +#else
> +static inline unsigned long opp_get_voltage(const struct opp *opp)
> +{
> +     return 0;
> +}
> +
> +static inline unsigned long opp_get_freq(const struct opp *opp)
> +{
> +     return 0;
> +}
> +
> +static inline int opp_get_opp_count(struct device *dev)
> +{
> +     return 0;
> +}
> +
> +static inline struct opp *opp_find_freq_exact(struct device *dev,
> +                                  unsigned long freq, bool enabled)
> +{
> +     return ERR_PTR(-EINVAL);
> +}
> +
> +static inline struct opp *opp_find_freq_floor(struct device *dev,
> +                                     unsigned long *freq)
> +{
> +     return ERR_PTR(-EINVAL);
> +}
> +
> +static inline struct opp *opp_find_freq_ceil(struct device *dev,
> +                                     unsigned long *freq)
> +{
> +     return ERR_PTR(-EINVAL);
> +}
> +
> +static inline int opp_add(struct device *dev, const struct opp_def
> *opp_def)
> +{
> +     return ERR_PTR(-EINVAL);
> +}
> +
> +static inline int opp_enable(struct opp *opp)
> +{
> +     return 0;
> +}
> +
> +static inline int opp_disable(struct opp *opp)
> +{
> +     return 0;
> +}
> +
> +static inline void opp_init_cpufreq_table(struct device *dev,
> +                         struct cpufreq_frequency_table **table)
> +{
> +}
> +
> +#endif               /* CONFIG_PM */
> +#endif               /* __ASM_OPP_H */
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index ca6066a..634eab6 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -242,3 +242,17 @@ config PM_OPS
>       bool
>       depends on PM_SLEEP || PM_RUNTIME
>       default y
> +
> +config PM_OPP
> +     bool "Enable Operating Performance Point(OPP) Layer library"
> +     depends on PM
> +     ---help---
> +       SOCs have a standard set of tuples consisting of frequency and
> +       voltage pairs that the device will support per voltage domain.
> This
> +       is called Operating Performance Point or OPP. The actual
> definitions
> +       of OPP varies over silicon within the same family of devices.
> +
> +       OPP layer organizes the data internally using device pointers
> +       representing individual voltage domains and provides SOC
> +       implementations a ready to use framework to manage OPPs.
> +       For more information, read <file:Documentation/power/opp.txt>
> diff --git a/lib/Makefile b/lib/Makefile
> index e6a3763..0114fcf 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -88,6 +88,8 @@ obj-$(CONFIG_IOMMU_HELPER) += iommu-helper.o
>  obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
>  obj-$(CONFIG_CPU_NOTIFIER_ERROR_INJECT) += cpu-notifier-error-inject.o
>
> +obj-$(CONFIG_PM_OPP) += opp.o
> +
>  lib-$(CONFIG_GENERIC_BUG) += bug.o
>
>  obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o
> diff --git a/lib/opp.c b/lib/opp.c
> new file mode 100644
> index 0000000..650c8c3
> --- /dev/null
> +++ b/lib/opp.c
> @@ -0,0 +1,440 @@
> +/*
> + * Generic OPP Interface
> + *
> + * Copyright (C) 2009-2010 Texas Instruments Incorporated.
> + *   Nishanth Menon
> + *   Romit Dasgupta <romit@xxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/cpufreq.h>
> +#include <linux/list.h>
> +#include <linux/opp.h>
> +
> +/**
> + * struct opp - Generic OPP description structure
> + * @node:    list node
> + * @enabled: true/false - marking this OPP as enabled/disabled
> + * @rate:    Frequency in hertz
> + * @u_volt:  Nominal voltage in microvolts corresponding to this OPP
> + * @dev_opp: contains the device_opp struct
> + *
> + * This structure stores the OPP information for a given domain.
> + */
> +struct opp {
> +     struct list_head node;
> +
> +     bool enabled;
> +     unsigned long rate;
> +     unsigned long u_volt;
> +
> +     struct device_opp *dev_opp;
> +};
> +
> +/**
> + * struct device_opp - Device opp structure
> + * @node:    list node
> + * @dev:     device handle
> + * @opp_list:        list of opps
> + * @opp_count:       num opps
> + * @enabled_opp_count:       how many opps are actually enabled
> + *
> + * This is an internal datastructure maintaining the link to
> + * opps attached to a domain device. This structure is not
> + * meant to be shared with users as it private to opp layer.

"... as it is private ..."

> + */
> +struct device_opp {
> +     struct list_head node;
> +
> +     struct device *dev;
> +
> +     struct list_head opp_list;
> +     u32 opp_count;
> +     u32 enabled_opp_count;
> +};
> +
> +static LIST_HEAD(dev_opp_list);
> +
> +/**
> + * find_device_opp() - find device_opp struct using device pointer
> + * @dev:     device pointer used to lookup device OPPs
> + *
> + * Search list of device OPPs for one containing matching device.
> + *
> + * Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or
> + * -EINVAL based on type of error.
> + */
> +static struct device_opp *find_device_opp(struct device *dev)
> +{
> +     struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
> +
> +     if (unlikely(!dev || IS_ERR(dev))) {
> +             pr_err("%s: Invalid parameters being passed\n", __func__);
> +             return ERR_PTR(-EINVAL);
> +     }
> +
> +     list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) {
> +             if (tmp_dev_opp->dev == dev) {
> +                     dev_opp = tmp_dev_opp;
> +                     break;
> +             }
> +     }
> +
> +     return dev_opp;
> +}
> +
> +/**
> + * opp_get_voltage() - Gets the voltage corresponding to an opp
> + * @opp:     opp for which voltage has to be returned for
> + *
> + * Return voltage in micro volt corresponding to the opp, else
> + * return 0
> + */
> +unsigned long opp_get_voltage(const struct opp *opp)
> +{
> +     if (unlikely(!opp || IS_ERR(opp)) || !opp->enabled) {
> +             pr_err("%s: Invalid parameters being passed\n", __func__);
> +             return 0;

Shouldn't the case for !opp->enabled just return 0, without error reporting.

IMHO, having an OPP disabled is not really a bug in params, and returning this, will misinform the user.. I think.

What do you think?

> +     }
> +
> +     return opp->u_volt;
> +}
> +
> +/**
> + * opp_get_freq() - Gets the frequency corresponding to an opp
> + * @opp:     opp for which frequency has to be returned for
> + *
> + * Return frequency in hertz corresponding to the opp, else
> + * return 0
> + */
> +unsigned long opp_get_freq(const struct opp *opp)
> +{
> +     if (unlikely(!opp || IS_ERR(opp)) || !opp->enabled) {
> +             pr_err("%s: Invalid parameters being passed\n", __func__);
> +             return 0;

Similarly here.

> +     }
> +
> +     return opp->rate;
> +}
> +
> +/**
> + * opp_get_opp_count() - Get number of opps enabled in the opp list
> + * @dev:     device for which we do this operation
> + *
> + * This functions returns the number of opps if there are any OPPs

"This function returns.."

> enabled,
> + * else returns corresponding error value.
> + */
> +int opp_get_opp_count(struct device *dev)
> +{
> +     struct device_opp *dev_opp;
> +
> +     dev_opp = find_device_opp(dev);
> +     if (IS_ERR(dev_opp))
> +             return -ENODEV;
> +
> +     return dev_opp->enabled_opp_count;
> +}
> +
> +/**
> + * opp_find_freq_exact() - search for an exact frequency
> + * @dev:     device for which we do this operation
> + * @freq:    frequency to search for
> + * @enabled: enabled/disabled OPP to search for
> + *
> + * Searches for exact match in the opp list and returns handle to the
> matching
> + * opp if found, else returns ERR_PTR in case of error and should be
> handled
> + * using IS_ERR.
> + *
> + * Note: enabled is a modifier for the search. if enabled=true, then the
> match
> + * is for exact matching frequency and is enabled. if false, the match is
> for
> + * exact frequency which is disabled.

That enabled var is ignored, which makes this explanation mismatch with the code behavior.

Am I missing something?

> + */
> +struct opp *opp_find_freq_exact(struct device *dev,
> +                                  unsigned long freq, bool enabled)
> +{
> +     struct device_opp *dev_opp;
> +     struct opp *temp_opp, *opp = ERR_PTR(-ENODEV);
> +
> +     dev_opp = find_device_opp(dev);
> +     if (IS_ERR(dev_opp))
> +             return opp;
> +
> +     list_for_each_entry(temp_opp, &dev_opp->opp_list, node) {
> +             if (temp_opp->enabled && temp_opp->rate == freq) {
> +                     opp = temp_opp;
> +                     break;
> +             }
> +     }
> +
> +     return opp;
> +}
> +
> +/**
> + * opp_find_freq_ceil() - Search for an rounded ceil freq
> + * @dev:     device for which we do this operation
> + * @freq:    Start frequency
> + *
> + * Search for the matching ceil *enabled* OPP from a starting freq
> + * for a domain.
> + *
> + * Returns *opp and *freq is populated with the match, else
> + * returns NULL opp if no match, else returns ERR_PTR in case of error.

By looking at the code below, I don't think returning NULL is a possibility.

> + *
> + * Example usages:
> + *   * find match/next highest available frequency *
> + *   freq = 350000;
> + *   opp = opp_find_freq_ceil(dev, &freq))
> + *   if (IS_ERR(opp))
> + *           pr_err("unable to find a higher frequency\n");
> + *   else
> + *           pr_info("match freq = %ld\n", freq);
> + *
> + *   * print all supported frequencies in ascending order *
> + *   freq = 0; * Search for the lowest enabled frequency *
> + *   while (!IS_ERR(opp = opp_find_freq_ceil(OPP_MPU, &freq)) {
> + *           pr_info("freq = %ld\n", freq);
> + *           freq++; * for next higher match *
> + *   }
> + */
> +struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq)
> +{
> +     struct device_opp *dev_opp;
> +     struct opp *temp_opp, *opp = ERR_PTR(-ENODEV);
> +
> +     dev_opp = find_device_opp(dev);
> +     if (IS_ERR(dev_opp))
> +             return opp;
> +
> +     list_for_each_entry(temp_opp, &dev_opp->opp_list, node) {
> +             if (temp_opp->enabled && temp_opp->rate >= *freq) {

What if freq contains a NULL pointer?

> +                     opp = temp_opp;
> +                     *freq = opp->rate;
> +                     break;
> +             }
> +     }
> +
> +     return opp;
> +}
> +
> +/**
> + * opp_find_freq_floor() - Search for an rounded floor freq

"... Search for a rounded floor ..."

> + * @dev:     device for which we do this operation
> + * @freq:    Start frequency
> + *
> + * Search for the matching floor *enabled* OPP from a starting freq
> + * for a domain.
> + *
> + * Returns *opp and *freq is populated with the next match, else
> + * returns NULL opp if no match, else returns ERR_PTR in case of error.

Similar comment about opp not being ever NULL as the function above.


Regards,
Sergio

> + *
> + * Example usages:
> + *   * find match/next lowest available frequency
> + *   freq = 350000;
> + *   opp = opp_find_freq_floor(dev, &freq)))
> + *   if (IS_ERR(opp))
> + *           pr_err ("unable to find a lower frequency\n");
> + *   else
> + *           pr_info("match freq = %ld\n", freq);
> + *
> + *   * print all supported frequencies in descending order *
> + *   freq = ULONG_MAX; * search highest enabled frequency *
> + *   while (!IS_ERR(opp = opp_find_freq_floor(OPP_MPU, &freq)) {
> + *           pr_info("freq = %ld\n", freq);
> + *           freq--; * for next lower match *
> + *   }
> + */
> +struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq)
> +{
> +     struct device_opp *dev_opp;
> +     struct opp *temp_opp, *opp = ERR_PTR(-ENODEV);
> +
> +     dev_opp = find_device_opp(dev);
> +     if (IS_ERR(dev_opp))
> +             return opp;
> +
> +     list_for_each_entry_reverse(temp_opp, &dev_opp->opp_list, node) {
> +             if (temp_opp->enabled && temp_opp->rate <= *freq) {
> +                     opp = temp_opp;
> +                     *freq = opp->rate;
> +                     break;
> +             }
> +     }
> +
> +     return opp;
> +}
> +
> +/* wrapper to reuse converting opp_def to opp struct */
> +static void opp_populate(struct opp *opp,
> +                           const struct opp_def *opp_def)
> +{
> +     opp->rate = opp_def->freq;
> +     opp->enabled = opp_def->enabled;
> +     opp->u_volt = opp_def->u_volt;
> +}
> +
> +/**
> + * opp_add()  - Add an OPP table from a table definitions
> + * @dev:     device for which we do this operation
> + * @opp_def: opp_def to describe the OPP which we want to add.
> + *
> + * This function adds an opp definition to the opp list and returns
> status.
> + */
> +int opp_add(struct device *dev, const struct opp_def *opp_def)
> +{
> +     struct device_opp *tmp_dev_opp, *dev_opp = NULL;
> +     struct opp *opp, *new_opp;
> +     struct list_head *head;
> +
> +     /* Check for existing list for 'dev' */
> +     list_for_each_entry(tmp_dev_opp, &dev_opp_list, node) {
> +             if (dev == tmp_dev_opp->dev) {
> +                     dev_opp = tmp_dev_opp;
> +                     break;
> +             }
> +     }
> +
> +     if (!dev_opp) {
> +             /* Allocate a new device OPP table */
> +             dev_opp = kzalloc(sizeof(struct device_opp), GFP_KERNEL);
> +             if (!dev_opp) {
> +                     pr_warning("%s: unable to allocate device struct\n",
> +                             __func__);
> +                     return -ENOMEM;
> +             }
> +
> +             dev_opp->dev = dev;
> +             INIT_LIST_HEAD(&dev_opp->opp_list);
> +
> +             list_add(&dev_opp->node, &dev_opp_list);
> +     }
> +
> +     /* allocate new OPP node */
> +     new_opp = kzalloc(sizeof(struct opp), GFP_KERNEL);
> +     if (!new_opp) {
> +             if (list_empty(&dev_opp->opp_list)) {
> +                     list_del(&dev_opp->node);
> +                     kfree(dev_opp);
> +             }
> +             pr_warning("%s: unable to allocate new opp node\n",
> +                     __func__);
> +             return -ENOMEM;
> +     }
> +     opp_populate(new_opp, opp_def);
> +
> +     /* Insert new OPP in order of increasing frequency */
> +     head = &dev_opp->opp_list;
> +     list_for_each_entry_reverse(opp, &dev_opp->opp_list, node) {
> +             if (new_opp->rate >= opp->rate) {
> +                     head = &opp->node;
> +                     break;
> +             }
> +     }
> +     list_add(&new_opp->node, head);
> +     dev_opp->opp_count++;
> +     if (new_opp->enabled)
> +             dev_opp->enabled_opp_count++;
> +
> +     return 0;
> +}
> +
> +/**
> + * opp_enable() - Enable a specific OPP
> + * @opp:     Pointer to opp
> + *
> + * Enables a provided opp. If the operation is valid, this returns 0,
> else the
> + * corresponding error value.
> + *
> + * OPP used here is from the the opp_is_valid/opp_has_freq or other
> search
> + * functions
> + */
> +int opp_enable(struct opp *opp)
> +{
> +     if (unlikely(!opp || IS_ERR(opp))) {
> +             pr_err("%s: Invalid parameters being passed\n", __func__);
> +             return -EINVAL;
> +     }
> +
> +     if (!opp->enabled && opp->dev_opp)
> +             opp->dev_opp->enabled_opp_count++;
> +
> +     opp->enabled = true;
> +
> +     return 0;
> +}
> +
> +/**
> + * opp_disable() - Disable a specific OPP
> + * @opp:     Pointer to opp
> + *
> + * Disables a provided opp. If the operation is valid, this returns 0,
> else the
> + * corresponding error value.
> + *
> + * OPP used here is from the the opp_is_valid/opp_has_freq or other
> search
> + * functions
> + */
> +int opp_disable(struct opp *opp)
> +{
> +     if (unlikely(!opp || IS_ERR(opp))) {
> +             pr_err("%s: Invalid parameters being passed\n", __func__);
> +             return -EINVAL;
> +     }
> +
> +     if (opp->enabled && opp->dev_opp)
> +             opp->dev_opp->enabled_opp_count--;
> +
> +     opp->enabled = false;
> +
> +     return 0;
> +}
> +
> +/**
> + * opp_init_cpufreq_table() - create a cpufreq table for a domain
> + * @dev:     device for which we do this operation
> + * @table:   Cpufreq table returned back to caller
> + *
> + * Generate a cpufreq table for a provided domain - this assumes that the
> + * opp list is already initialized and ready for usage
> + */
> +void opp_init_cpufreq_table(struct device *dev,
> +                         struct cpufreq_frequency_table **table)
> +{
> +     struct device_opp *dev_opp;
> +     struct opp *opp;
> +     struct cpufreq_frequency_table *freq_table;
> +     int i = 0;
> +
> +     dev_opp = find_device_opp(dev);
> +     if (IS_ERR(dev_opp)) {
> +             pr_warning("%s: unable to find device\n", __func__);
> +             return;
> +     }
> +
> +     freq_table = kzalloc(sizeof(struct cpufreq_frequency_table) *
> +                          (dev_opp->enabled_opp_count + 1), GFP_ATOMIC);
> +     if (!freq_table) {
> +             pr_warning("%s: failed to allocate frequency table\n",
> +                        __func__);
> +             return;
> +     }
> +
> +     list_for_each_entry(opp, &dev_opp->opp_list, node) {
> +             if (opp->enabled) {
> +                     freq_table[i].index = i;
> +                     freq_table[i].frequency = opp->rate / 1000;
> +                     i++;
> +             }
> +     }
> +
> +     freq_table[i].index = i;
> +     freq_table[i].frequency = CPUFREQ_TABLE_END;
> +
> +     *table = &freq_table[0];
> +}
> --
> 1.6.3.3

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