1/*
  2 * arch/arm/mach-tegra/cpu-tegra.c
  3 *
  4 * Copyright (C) 2010 Google, Inc.
  5 *
  6 * Author:
  7 *	Colin Cross <ccross@google.com>
  8 *	Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
  9 *
 10 * This software is licensed under the terms of the GNU General Public
 11 * License version 2, as published by the Free Software Foundation, and
 12 * may be copied, distributed, and modified under those terms.
 13 *
 14 * This program is distributed in the hope that it will be useful,
 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 17 * GNU General Public License for more details.
 18 *
 19 */
 20
 21#include <linux/kernel.h>
 22#include <linux/module.h>
 23#include <linux/types.h>
 24#include <linux/sched.h>
 25#include <linux/cpufreq.h>
 26#include <linux/delay.h>
 27#include <linux/init.h>
 28#include <linux/err.h>
 29#include <linux/clk.h>
 30#include <linux/io.h>
 31#include <linux/suspend.h>
 32
 33
 34#include <mach/clk.h>
 35
 36/* Frequency table index must be sequential starting at 0 */
 37static struct cpufreq_frequency_table freq_table[] = {
 38	{ 0, 216000 },
 39	{ 1, 312000 },
 40	{ 2, 456000 },
 41	{ 3, 608000 },
 42	{ 4, 760000 },
 43	{ 5, 816000 },
 44	{ 6, 912000 },
 45	{ 7, 1000000 },
 46	{ 8, CPUFREQ_TABLE_END },
 47};
 48
 49#define NUM_CPUS	2
 50
 51static struct clk *cpu_clk;
 52static struct clk *emc_clk;
 53
 54static unsigned long target_cpu_speed[NUM_CPUS];
 55static DEFINE_MUTEX(tegra_cpu_lock);
 56static bool is_suspended;
 57
 58static int tegra_verify_speed(struct cpufreq_policy *policy)
 59{
 60	return cpufreq_frequency_table_verify(policy, freq_table);
 61}
 62
 63static unsigned int tegra_getspeed(unsigned int cpu)
 64{
 65	unsigned long rate;
 66
 67	if (cpu >= NUM_CPUS)
 68		return 0;
 69
 70	rate = clk_get_rate(cpu_clk) / 1000;
 71	return rate;
 72}
 73
 74static int tegra_update_cpu_speed(unsigned long rate)
 75{
 76	int ret = 0;
 77	struct cpufreq_freqs freqs;
 78
 79	freqs.old = tegra_getspeed(0);
 80	freqs.new = rate;
 81
 82	if (freqs.old == freqs.new)
 83		return ret;
 84
 85	/*
 86	 * Vote on memory bus frequency based on cpu frequency
 87	 * This sets the minimum frequency, display or avp may request higher
 88	 */
 89	if (rate >= 816000)
 90		clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
 91	else if (rate >= 456000)
 92		clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
 93	else
 94		clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
 95
 96	for_each_online_cpu(freqs.cpu)
 97		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 98
 99#ifdef CONFIG_CPU_FREQ_DEBUG
100	printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
101	       freqs.old, freqs.new);
102#endif
103
104	ret = clk_set_rate(cpu_clk, freqs.new * 1000);
105	if (ret) {
106		pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
107			freqs.new);
108		return ret;
109	}
110
111	for_each_online_cpu(freqs.cpu)
112		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
113
114	return 0;
115}
116
117static unsigned long tegra_cpu_highest_speed(void)
118{
119	unsigned long rate = 0;
120	int i;
121
122	for_each_online_cpu(i)
123		rate = max(rate, target_cpu_speed[i]);
124	return rate;
125}
126
127static int tegra_target(struct cpufreq_policy *policy,
128		       unsigned int target_freq,
129		       unsigned int relation)
130{
131	unsigned int idx;
132	unsigned int freq;
133	int ret = 0;
134
135	mutex_lock(&tegra_cpu_lock);
136
137	if (is_suspended) {
138		ret = -EBUSY;
139		goto out;
140	}
141
142	cpufreq_frequency_table_target(policy, freq_table, target_freq,
143		relation, &idx);
144
145	freq = freq_table[idx].frequency;
146
147	target_cpu_speed[policy->cpu] = freq;
148
149	ret = tegra_update_cpu_speed(tegra_cpu_highest_speed());
150
151out:
152	mutex_unlock(&tegra_cpu_lock);
153	return ret;
154}
155
156static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
157	void *dummy)
158{
159	mutex_lock(&tegra_cpu_lock);
160	if (event == PM_SUSPEND_PREPARE) {
161		is_suspended = true;
162		pr_info("Tegra cpufreq suspend: setting frequency to %d kHz\n",
163			freq_table[0].frequency);
164		tegra_update_cpu_speed(freq_table[0].frequency);
165	} else if (event == PM_POST_SUSPEND) {
166		is_suspended = false;
167	}
168	mutex_unlock(&tegra_cpu_lock);
169
170	return NOTIFY_OK;
171}
172
173static struct notifier_block tegra_cpu_pm_notifier = {
174	.notifier_call = tegra_pm_notify,
175};
176
177static int tegra_cpu_init(struct cpufreq_policy *policy)
178{
179	if (policy->cpu >= NUM_CPUS)
180		return -EINVAL;
181
182	cpu_clk = clk_get_sys(NULL, "cpu");
183	if (IS_ERR(cpu_clk))
184		return PTR_ERR(cpu_clk);
185
186	emc_clk = clk_get_sys("cpu", "emc");
187	if (IS_ERR(emc_clk)) {
188		clk_put(cpu_clk);
189		return PTR_ERR(emc_clk);
190	}
191
192	clk_enable(emc_clk);
193	clk_enable(cpu_clk);
194
195	cpufreq_frequency_table_cpuinfo(policy, freq_table);
196	cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
197	policy->cur = tegra_getspeed(policy->cpu);
198	target_cpu_speed[policy->cpu] = policy->cur;
199
200	/* FIXME: what's the actual transition time? */
201	policy->cpuinfo.transition_latency = 300 * 1000;
202
203	policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
204	cpumask_copy(policy->related_cpus, cpu_possible_mask);
205
206	if (policy->cpu == 0)
207		register_pm_notifier(&tegra_cpu_pm_notifier);
208
209	return 0;
210}
211
212static int tegra_cpu_exit(struct cpufreq_policy *policy)
213{
214	cpufreq_frequency_table_cpuinfo(policy, freq_table);
215	clk_disable(emc_clk);
216	clk_put(emc_clk);
217	clk_put(cpu_clk);
218	return 0;
219}
220
221static struct freq_attr *tegra_cpufreq_attr[] = {
222	&cpufreq_freq_attr_scaling_available_freqs,
223	NULL,
224};
225
226static struct cpufreq_driver tegra_cpufreq_driver = {
227	.verify		= tegra_verify_speed,
228	.target		= tegra_target,
229	.get		= tegra_getspeed,
230	.init		= tegra_cpu_init,
231	.exit		= tegra_cpu_exit,
232	.name		= "tegra",
233	.attr		= tegra_cpufreq_attr,
234};
235
236static int __init tegra_cpufreq_init(void)
237{
238	return cpufreq_register_driver(&tegra_cpufreq_driver);
239}
240
241static void __exit tegra_cpufreq_exit(void)
242{
243        cpufreq_unregister_driver(&tegra_cpufreq_driver);
244}
245
246
247MODULE_AUTHOR("Colin Cross <ccross@android.com>");
248MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
249MODULE_LICENSE("GPL");
250module_init(tegra_cpufreq_init);
251module_exit(tegra_cpufreq_exit);