1/*
2 *  CPU frequency scaling for OMAP using OPP information
3 *
4 *  Copyright (C) 2005 Nokia Corporation
5 *  Written by Tony Lindgren <tony@atomide.com>
6 *
7 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
8 *
9 * Copyright (C) 2007-2011 Texas Instruments, Inc.
10 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 */
16#include <linux/types.h>
17#include <linux/kernel.h>
18#include <linux/sched.h>
19#include <linux/cpufreq.h>
20#include <linux/delay.h>
21#include <linux/init.h>
22#include <linux/err.h>
23#include <linux/clk.h>
24#include <linux/io.h>
25#include <linux/pm_opp.h>
26#include <linux/cpu.h>
27#include <linux/module.h>
28#include <linux/platform_device.h>
29#include <linux/regulator/consumer.h>
30
31#include <asm/smp_plat.h>
32#include <asm/cpu.h>
33
34/* OPP tolerance in percentage */
35#define	OPP_TOLERANCE	4
36
37static struct cpufreq_frequency_table *freq_table;
38static atomic_t freq_table_users = ATOMIC_INIT(0);
39static struct device *mpu_dev;
40static struct regulator *mpu_reg;
41
42static int omap_target(struct cpufreq_policy *policy, unsigned int index)
43{
44	int r, ret;
45	struct dev_pm_opp *opp;
46	unsigned long freq, volt = 0, volt_old = 0, tol = 0;
47	unsigned int old_freq, new_freq;
48
49	old_freq = policy->cur;
50	new_freq = freq_table[index].frequency;
51
52	freq = new_freq * 1000;
53	ret = clk_round_rate(policy->clk, freq);
54	if (IS_ERR_VALUE(ret)) {
55		dev_warn(mpu_dev,
56			 "CPUfreq: Cannot find matching frequency for %lu\n",
57			 freq);
58		return ret;
59	}
60	freq = ret;
61
62	if (mpu_reg) {
63		rcu_read_lock();
64		opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
65		if (IS_ERR(opp)) {
66			rcu_read_unlock();
67			dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
68				__func__, new_freq);
69			return -EINVAL;
70		}
71		volt = dev_pm_opp_get_voltage(opp);
72		rcu_read_unlock();
73		tol = volt * OPP_TOLERANCE / 100;
74		volt_old = regulator_get_voltage(mpu_reg);
75	}
76
77	dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
78		old_freq / 1000, volt_old ? volt_old / 1000 : -1,
79		new_freq / 1000, volt ? volt / 1000 : -1);
80
81	/* scaling up?  scale voltage before frequency */
82	if (mpu_reg && (new_freq > old_freq)) {
83		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
84		if (r < 0) {
85			dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
86				 __func__);
87			return r;
88		}
89	}
90
91	ret = clk_set_rate(policy->clk, new_freq * 1000);
92
93	/* scaling down?  scale voltage after frequency */
94	if (mpu_reg && (new_freq < old_freq)) {
95		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
96		if (r < 0) {
97			dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
98				 __func__);
99			clk_set_rate(policy->clk, old_freq * 1000);
100			return r;
101		}
102	}
103
104	return ret;
105}
106
107static inline void freq_table_free(void)
108{
109	if (atomic_dec_and_test(&freq_table_users))
110		dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
111}
112
113static int omap_cpu_init(struct cpufreq_policy *policy)
114{
115	int result;
116
117	policy->clk = clk_get(NULL, "cpufreq_ck");
118	if (IS_ERR(policy->clk))
119		return PTR_ERR(policy->clk);
120
121	if (!freq_table) {
122		result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
123		if (result) {
124			dev_err(mpu_dev,
125				"%s: cpu%d: failed creating freq table[%d]\n",
126				__func__, policy->cpu, result);
127			goto fail;
128		}
129	}
130
131	atomic_inc_return(&freq_table_users);
132
133	/* FIXME: what's the actual transition time? */
134	result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
135	if (!result)
136		return 0;
137
138	freq_table_free();
139fail:
140	clk_put(policy->clk);
141	return result;
142}
143
144static int omap_cpu_exit(struct cpufreq_policy *policy)
145{
146	freq_table_free();
147	clk_put(policy->clk);
148	return 0;
149}
150
151static struct cpufreq_driver omap_driver = {
152	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
153	.verify		= cpufreq_generic_frequency_table_verify,
154	.target_index	= omap_target,
155	.get		= cpufreq_generic_get,
156	.init		= omap_cpu_init,
157	.exit		= omap_cpu_exit,
158	.name		= "omap",
159	.attr		= cpufreq_generic_attr,
160};
161
162static int omap_cpufreq_probe(struct platform_device *pdev)
163{
164	mpu_dev = get_cpu_device(0);
165	if (!mpu_dev) {
166		pr_warning("%s: unable to get the mpu device\n", __func__);
167		return -EINVAL;
168	}
169
170	mpu_reg = regulator_get(mpu_dev, "vcc");
171	if (IS_ERR(mpu_reg)) {
172		pr_warning("%s: unable to get MPU regulator\n", __func__);
173		mpu_reg = NULL;
174	} else {
175		/*
176		 * Ensure physical regulator is present.
177		 * (e.g. could be dummy regulator.)
178		 */
179		if (regulator_get_voltage(mpu_reg) < 0) {
180			pr_warn("%s: physical regulator not present for MPU\n",
181				__func__);
182			regulator_put(mpu_reg);
183			mpu_reg = NULL;
184		}
185	}
186
187	return cpufreq_register_driver(&omap_driver);
188}
189
190static int omap_cpufreq_remove(struct platform_device *pdev)
191{
192	return cpufreq_unregister_driver(&omap_driver);
193}
194
195static struct platform_driver omap_cpufreq_platdrv = {
196	.driver = {
197		.name	= "omap-cpufreq",
198	},
199	.probe		= omap_cpufreq_probe,
200	.remove		= omap_cpufreq_remove,
201};
202module_platform_driver(omap_cpufreq_platdrv);
203
204MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
205MODULE_LICENSE("GPL");
206