blob: f7a32d2326c6428f4f4e8b1000381b7dc4301e5f [file] [log] [blame]
* Generic OPP helper interface for CPUFreq drivers
* Copyright (C) 2009-2014 Texas Instruments Incorporated.
* Nishanth Menon
* Romit Dasgupta
* Kevin Hilman
* 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/cpufreq.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/pm_opp.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
* dev_pm_opp_init_cpufreq_table() - create a cpufreq table for a device
* @dev: device for which we do this operation
* @table: Cpufreq table returned back to caller
* Generate a cpufreq table for a provided device- this assumes that the
* opp list is already initialized and ready for usage.
* This function allocates required memory for the cpufreq table. It is
* expected that the caller does the required maintenance such as freeing
* the table as required.
* Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM
* if no memory available for the operation (table is not populated), returns 0
* if successful and table is populated.
* WARNING: It is important for the callers to ensure refreshing their copy of
* the table if any of the mentioned functions have been invoked in the interim.
* Locking: The internal device_opp and opp structures are RCU protected.
* Since we just use the regular accessor functions to access the internal data
* structures, we use RCU read lock inside this function. As a result, users of
* this function DONOT need to use explicit locks for invoking.
int dev_pm_opp_init_cpufreq_table(struct device *dev,
struct cpufreq_frequency_table **table)
struct dev_pm_opp *opp;
struct cpufreq_frequency_table *freq_table = NULL;
int i, max_opps, ret = 0;
unsigned long rate;
max_opps = dev_pm_opp_get_opp_count(dev);
if (max_opps <= 0) {
ret = max_opps ? max_opps : -ENODATA;
goto out;
freq_table = kcalloc(sizeof(*freq_table), (max_opps + 1), GFP_ATOMIC);
if (!freq_table) {
ret = -ENOMEM;
goto out;
for (i = 0, rate = 0; i < max_opps; i++, rate++) {
/* find next rate */
opp = dev_pm_opp_find_freq_ceil(dev, &rate);
if (IS_ERR(opp)) {
ret = PTR_ERR(opp);
goto out;
freq_table[i].driver_data = i;
freq_table[i].frequency = rate / 1000;
freq_table[i].driver_data = i;
freq_table[i].frequency = CPUFREQ_TABLE_END;
*table = &freq_table[0];
if (ret)
return ret;
* dev_pm_opp_free_cpufreq_table() - free the cpufreq table
* @dev: device for which we do this operation
* @table: table to free
* Free up the table allocated by dev_pm_opp_init_cpufreq_table
void dev_pm_opp_free_cpufreq_table(struct device *dev,
struct cpufreq_frequency_table **table)
if (!table)
*table = NULL;