1/*
2 * Generic big.LITTLE CPUFreq Interface driver
3 *
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.
6 *
7 * Copyright (C) 2013 Linaro.
8 * Viresh Kumar <viresh.kumar@linaro.org>
9 *
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.
13 *
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.
18 */
19
20#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/cpufreq.h>
23#include <linux/device.h>
24#include <linux/export.h>
25#include <linux/module.h>
26#include <linux/of_device.h>
27#include <linux/pm_opp.h>
28#include <linux/platform_device.h>
29#include <linux/slab.h>
30#include <linux/types.h>
31#include "arm_big_little.h"
32
33/* get cpu node with valid operating-points */
34static struct device_node *get_cpu_node_with_valid_op(int cpu)
35{
36	struct device_node *np = of_cpu_device_node_get(cpu);
37
38	if (!of_get_property(np, "operating-points", NULL)) {
39		of_node_put(np);
40		np = NULL;
41	}
42
43	return np;
44}
45
46static int dt_init_opp_table(struct device *cpu_dev)
47{
48	struct device_node *np;
49	int ret;
50
51	np = of_node_get(cpu_dev->of_node);
52	if (!np) {
53		pr_err("failed to find cpu%d node\n", cpu_dev->id);
54		return -ENOENT;
55	}
56
57	ret = of_init_opp_table(cpu_dev);
58	of_node_put(np);
59
60	return ret;
61}
62
63static int dt_get_transition_latency(struct device *cpu_dev)
64{
65	struct device_node *np;
66	u32 transition_latency = CPUFREQ_ETERNAL;
67
68	np = of_node_get(cpu_dev->of_node);
69	if (!np) {
70		pr_info("Failed to find cpu node. Use CPUFREQ_ETERNAL transition latency\n");
71		return CPUFREQ_ETERNAL;
72	}
73
74	of_property_read_u32(np, "clock-latency", &transition_latency);
75	of_node_put(np);
76
77	pr_debug("%s: clock-latency: %d\n", __func__, transition_latency);
78	return transition_latency;
79}
80
81static struct cpufreq_arm_bL_ops dt_bL_ops = {
82	.name	= "dt-bl",
83	.get_transition_latency = dt_get_transition_latency,
84	.init_opp_table = dt_init_opp_table,
85	.free_opp_table = of_free_opp_table,
86};
87
88static int generic_bL_probe(struct platform_device *pdev)
89{
90	struct device_node *np;
91
92	np = get_cpu_node_with_valid_op(0);
93	if (!np)
94		return -ENODEV;
95
96	of_node_put(np);
97	return bL_cpufreq_register(&dt_bL_ops);
98}
99
100static int generic_bL_remove(struct platform_device *pdev)
101{
102	bL_cpufreq_unregister(&dt_bL_ops);
103	return 0;
104}
105
106static struct platform_driver generic_bL_platdrv = {
107	.driver = {
108		.name	= "arm-bL-cpufreq-dt",
109	},
110	.probe		= generic_bL_probe,
111	.remove		= generic_bL_remove,
112};
113module_platform_driver(generic_bL_platdrv);
114
115MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
116MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
117MODULE_LICENSE("GPL v2");
118