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/cpu.h>
23 #include <linux/cpufreq.h>
24 #include <linux/device.h>
25 #include <linux/export.h>
26 #include <linux/module.h>
28 #include <linux/opp.h>
29 #include <linux/slab.h>
30 #include <linux/types.h>
31 #include "arm_big_little.h"
33 /* get cpu node with valid operating-points */
34 static struct device_node *get_cpu_node_with_valid_op(int cpu)
36 struct device_node *np = NULL, *parent;
39 parent = of_find_node_by_path("/cpus");
41 pr_err("failed to find OF /cpus\n");
45 for_each_child_of_node(parent, np) {
48 if (!of_get_property(np, "operating-points", NULL)) {
60 static int dt_init_opp_table(struct device *cpu_dev)
62 struct device_node *np;
65 np = get_cpu_node_with_valid_op(cpu_dev->id);
69 cpu_dev->of_node = np;
70 ret = of_init_opp_table(cpu_dev);
76 static int dt_get_transition_latency(struct device *cpu_dev)
78 struct device_node *np;
79 u32 transition_latency = CPUFREQ_ETERNAL;
81 np = get_cpu_node_with_valid_op(cpu_dev->id);
83 return CPUFREQ_ETERNAL;
85 of_property_read_u32(np, "clock-latency", &transition_latency);
88 pr_debug("%s: clock-latency: %d\n", __func__, transition_latency);
89 return transition_latency;
92 static struct cpufreq_arm_bL_ops dt_bL_ops = {
94 .get_transition_latency = dt_get_transition_latency,
95 .init_opp_table = dt_init_opp_table,
98 static int generic_bL_init(void)
100 struct device_node *np;
102 np = get_cpu_node_with_valid_op(0);
107 return bL_cpufreq_register(&dt_bL_ops);
109 module_init(generic_bL_init);
111 static void generic_bL_exit(void)
113 return bL_cpufreq_unregister(&dt_bL_ops);
115 module_exit(generic_bL_exit);
117 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
118 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
119 MODULE_LICENSE("GPL");