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 */
dev_pm_opp_init_cpufreq_table(struct device * dev,struct cpufreq_frequency_table ** table)47 int 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
85 out:
86 rcu_read_unlock();
87 if (ret)
88 kfree(freq_table);
89
90 return ret;
91 }
92 EXPORT_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 */
dev_pm_opp_free_cpufreq_table(struct device * dev,struct cpufreq_frequency_table ** table)101 void 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 }
110 EXPORT_SYMBOL_GPL(dev_pm_opp_free_cpufreq_table);
111