2 * Generic big.LITTLE CPUFreq Interface driver
4 * It provides necessary ops to arm_big_little cpufreq driver and gets
5 * Frequency information from Device Tree. Freq table in DT must be in KHz.
7 * Copyright (C) 2013 Linaro.
8 * Viresh Kumar <viresh.kumar@linaro.org>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
14 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
15 * kind, whether express or implied; without even the implied warranty
16 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22 #include <linux/cpufreq.h>
23 #include <linux/device.h>
24 #include <linux/export.h>
25 #include <linux/module.h>
27 #include <linux/opp.h>
28 #include <linux/slab.h>
29 #include <linux/types.h>
30 #include "arm_big_little.h"
32 static int dt_init_opp_table(struct device *cpu_dev)
34 struct device_node *np, *parent;
37 parent = of_find_node_by_path("/cpus");
39 pr_err("failed to find OF /cpus\n");
43 for_each_child_of_node(parent, np) {
44 if (count++ != cpu_dev->id)
46 if (!of_get_property(np, "operating-points", NULL)) {
49 cpu_dev->of_node = np;
50 ret = of_init_opp_table(cpu_dev);
61 static int dt_get_transition_latency(struct device *cpu_dev)
63 struct device_node *np, *parent;
64 u32 transition_latency = CPUFREQ_ETERNAL;
67 parent = of_find_node_by_path("/cpus");
69 pr_info("Failed to find OF /cpus. Use CPUFREQ_ETERNAL transition latency\n");
70 return CPUFREQ_ETERNAL;
73 for_each_child_of_node(parent, np) {
74 if (count++ != cpu_dev->id)
77 of_property_read_u32(np, "clock-latency", &transition_latency);
81 return transition_latency;
84 pr_info("clock-latency isn't found, use CPUFREQ_ETERNAL transition latency\n");
85 return CPUFREQ_ETERNAL;
88 static struct cpufreq_arm_bL_ops dt_bL_ops = {
90 .get_transition_latency = dt_get_transition_latency,
91 .init_opp_table = dt_init_opp_table,
94 static int generic_bL_init(void)
96 return bL_cpufreq_register(&dt_bL_ops);
98 module_init(generic_bL_init);
100 static void generic_bL_exit(void)
102 return bL_cpufreq_unregister(&dt_bL_ops);
104 module_exit(generic_bL_exit);
106 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
107 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
108 MODULE_LICENSE("GPL");