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 = dev_pm_opp_of_add_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 = dev_pm_opp_of_remove_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");