mirror of https://gitee.com/openkylin/linux.git
111 lines
3.1 KiB
C
111 lines
3.1 KiB
C
/*
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* Generic OPP helper interface for CPUFreq drivers
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*
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* Copyright (C) 2009-2014 Texas Instruments Incorporated.
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* Nishanth Menon
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* Romit Dasgupta
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* Kevin Hilman
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/cpufreq.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/pm_opp.h>
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#include <linux/rcupdate.h>
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#include <linux/slab.h>
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/**
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* dev_pm_opp_init_cpufreq_table() - create a cpufreq table for a device
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* @dev: device for which we do this operation
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* @table: Cpufreq table returned back to caller
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*
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* Generate a cpufreq table for a provided device- this assumes that the
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* opp list is already initialized and ready for usage.
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*
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* This function allocates required memory for the cpufreq table. It is
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* expected that the caller does the required maintenance such as freeing
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* the table as required.
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*
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* Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM
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* if no memory available for the operation (table is not populated), returns 0
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* if successful and table is populated.
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*
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* WARNING: It is important for the callers to ensure refreshing their copy of
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* the table if any of the mentioned functions have been invoked in the interim.
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*
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* Locking: The internal device_opp and opp structures are RCU protected.
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* Since we just use the regular accessor functions to access the internal data
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* structures, we use RCU read lock inside this function. As a result, users of
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* this function DONOT need to use explicit locks for invoking.
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*/
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int dev_pm_opp_init_cpufreq_table(struct device *dev,
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struct cpufreq_frequency_table **table)
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{
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struct dev_pm_opp *opp;
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struct cpufreq_frequency_table *freq_table = NULL;
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int i, max_opps, ret = 0;
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unsigned long rate;
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rcu_read_lock();
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max_opps = dev_pm_opp_get_opp_count(dev);
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if (max_opps <= 0) {
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ret = max_opps ? max_opps : -ENODATA;
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goto out;
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}
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freq_table = kcalloc(sizeof(*freq_table), (max_opps + 1), GFP_ATOMIC);
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if (!freq_table) {
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ret = -ENOMEM;
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goto out;
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}
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for (i = 0, rate = 0; i < max_opps; i++, rate++) {
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/* find next rate */
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opp = dev_pm_opp_find_freq_ceil(dev, &rate);
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if (IS_ERR(opp)) {
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ret = PTR_ERR(opp);
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goto out;
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}
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freq_table[i].driver_data = i;
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freq_table[i].frequency = rate / 1000;
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}
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freq_table[i].driver_data = i;
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freq_table[i].frequency = CPUFREQ_TABLE_END;
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*table = &freq_table[0];
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out:
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rcu_read_unlock();
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if (ret)
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kfree(freq_table);
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return ret;
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}
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EXPORT_SYMBOL_GPL(dev_pm_opp_init_cpufreq_table);
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/**
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* dev_pm_opp_free_cpufreq_table() - free the cpufreq table
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* @dev: device for which we do this operation
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* @table: table to free
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*
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* Free up the table allocated by dev_pm_opp_init_cpufreq_table
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*/
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void dev_pm_opp_free_cpufreq_table(struct device *dev,
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struct cpufreq_frequency_table **table)
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{
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if (!table)
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return;
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kfree(*table);
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*table = NULL;
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}
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EXPORT_SYMBOL_GPL(dev_pm_opp_free_cpufreq_table);
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