1/*
2 * Generic OPP helper interface for CPUFreq drivers
3 *
4 * Copyright (C) 2009-2014 Texas Instruments Incorporated.
5 *	Nishanth Menon
6 *	Romit Dasgupta
7 *	Kevin Hilman
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13#include <linux/cpufreq.h>
14#include <linux/device.h>
15#include <linux/err.h>
16#include <linux/errno.h>
17#include <linux/export.h>
18#include <linux/kernel.h>
19#include <linux/pm_opp.h>
20#include <linux/rcupdate.h>
21#include <linux/slab.h>
22
23/**
24 * dev_pm_opp_init_cpufreq_table() - create a cpufreq table for a device
25 * @dev:	device for which we do this operation
26 * @table:	Cpufreq table returned back to caller
27 *
28 * Generate a cpufreq table for a provided device- this assumes that the
29 * opp list is already initialized and ready for usage.
30 *
31 * This function allocates required memory for the cpufreq table. It is
32 * expected that the caller does the required maintenance such as freeing
33 * the table as required.
34 *
35 * Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM
36 * if no memory available for the operation (table is not populated), returns 0
37 * if successful and table is populated.
38 *
39 * WARNING: It is  important for the callers to ensure refreshing their copy of
40 * the table if any of the mentioned functions have been invoked in the interim.
41 *
42 * Locking: The internal device_opp and opp structures are RCU protected.
43 * Since we just use the regular accessor functions to access the internal data
44 * structures, we use RCU read lock inside this function. As a result, users of
45 * this function DONOT need to use explicit locks for invoking.
46 */
47int dev_pm_opp_init_cpufreq_table(struct device *dev,
48				  struct cpufreq_frequency_table **table)
49{
50	struct dev_pm_opp *opp;
51	struct cpufreq_frequency_table *freq_table = NULL;
52	int i, max_opps, ret = 0;
53	unsigned long rate;
54
55	rcu_read_lock();
56
57	max_opps = dev_pm_opp_get_opp_count(dev);
58	if (max_opps <= 0) {
59		ret = max_opps ? max_opps : -ENODATA;
60		goto out;
61	}
62
63	freq_table = kcalloc((max_opps + 1), sizeof(*freq_table), GFP_ATOMIC);
64	if (!freq_table) {
65		ret = -ENOMEM;
66		goto out;
67	}
68
69	for (i = 0, rate = 0; i < max_opps; i++, rate++) {
70		/* find next rate */
71		opp = dev_pm_opp_find_freq_ceil(dev, &rate);
72		if (IS_ERR(opp)) {
73			ret = PTR_ERR(opp);
74			goto out;
75		}
76		freq_table[i].driver_data = i;
77		freq_table[i].frequency = rate / 1000;
78	}
79
80	freq_table[i].driver_data = i;
81	freq_table[i].frequency = CPUFREQ_TABLE_END;
82
83	*table = &freq_table[0];
84
85out:
86	rcu_read_unlock();
87	if (ret)
88		kfree(freq_table);
89
90	return ret;
91}
92EXPORT_SYMBOL_GPL(dev_pm_opp_init_cpufreq_table);
93
94/**
95 * dev_pm_opp_free_cpufreq_table() - free the cpufreq table
96 * @dev:	device for which we do this operation
97 * @table:	table to free
98 *
99 * Free up the table allocated by dev_pm_opp_init_cpufreq_table
100 */
101void dev_pm_opp_free_cpufreq_table(struct device *dev,
102				   struct cpufreq_frequency_table **table)
103{
104	if (!table)
105		return;
106
107	kfree(*table);
108	*table = NULL;
109}
110EXPORT_SYMBOL_GPL(dev_pm_opp_free_cpufreq_table);
111