/*
* Copyright (C) 2010 Google, Inc.
*
* Author:
* Colin Cross <ccross@google.com>
* Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/suspend.h>
/* Frequency table index must be sequential starting at 0 */
static struct cpufreq_frequency_table freq_table[] = {
{ 0, 216000 },
{ 1, 312000 },
{ 2, 456000 },
{ 3, 608000 },
{ 4, 760000 },
{ 5, 816000 },
{ 6, 912000 },
{ 7, 1000000 },
{ 8, CPUFREQ_TABLE_END },
};
#define NUM_CPUS 2
static struct clk *cpu_clk;
static struct clk *pll_x_clk;
static struct clk *pll_p_clk;
static struct clk *emc_clk;
static unsigned long target_cpu_speed[NUM_CPUS];
static DEFINE_MUTEX(tegra_cpu_lock);
static bool is_suspended;
static int tegra_verify_speed(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, freq_table);
}
static unsigned int tegra_getspeed(unsigned int cpu)
{
unsigned long rate;
if (cpu >= NUM_CPUS)
return 0;
rate = clk_get_rate(cpu_clk) / 1000;
return rate;
}
static int tegra_cpu_clk_set_rate(unsigned long rate)
{
int ret;
/*
* Take an extra reference to the main pll so it doesn't turn
* off when we move the cpu off of it
*/
clk_prepare_enable(pll_x_clk);
ret = clk_set_parent(cpu_clk, pll_p_clk);
if (ret) {
pr_err("Failed to switch cpu to clock pll_p\n");
goto out;
}
if (rate == clk_get_rate(pll_p_clk))
goto out;
ret = clk_set_rate(pll_x_clk, rate);
if (ret) {
pr_err("Failed to change pll_x to %lu\n", rate);
goto out;
}
ret = clk_set_parent(cpu_clk, pll_x_clk);
if (ret) {
pr_err("Failed to switch cpu to clock pll_x\n");
goto out;
}
out:
clk_disable_unprepare(pll_x_clk);
return ret;
}
static int tegra_update_cpu_speed(struct cpufreq_policy *policy,
unsigned long rate)
{
int ret = 0;
struct cpufreq_freqs freqs;
freqs.old = tegra_getspeed(0);
freqs.new = rate;
if (freqs.old == freqs.new)
return ret;
/*
* Vote on memory bus frequency based on cpu frequency
* This sets the minimum frequency, display or avp may request higher
*/
if (rate >= 816000)
clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
else if (rate >= 456000)
clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
else
clk_set_rate(emc_clk, 100000000); /* emc 50Mhz */
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
#ifdef CONFIG_CPU_FREQ_DEBUG
printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
freqs.old, freqs.new);
#endif
ret = tegra_cpu_clk_set_rate(freqs.new * 1000);
if (ret) {
pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
freqs.new);
return ret;
}
cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
return 0;
}
static unsigned long tegra_cpu_highest_speed(void)
{
unsigned long rate = 0;
int i;
for_each_online_cpu(i)
rate = max(rate, target_cpu_speed[i]);
return rate;
}
static int tegra_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
unsigned int idx;
unsigned int freq;
int ret = 0;
mutex_lock(&tegra_cpu_lock);
if (is_suspended) {
ret = -EBUSY;
goto out;
}
cpufreq_frequency_table_target(policy, freq_table, target_freq,
relation, &idx);
freq = freq_table[idx].frequency;
target_cpu_speed[policy->cpu] = freq;
ret = tegra_update_cpu_speed(policy, tegra_cpu_highest_speed());
out:
mutex_unlock(&tegra_cpu_lock);
return ret;
}
static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
void *dummy)
{
mutex_lock(&tegra_cpu_lock);
if (event == PM_SUSPEND_PREPARE) {
struct cpufreq_policy *policy = cpufreq_cpu_get(0);
is_suspended = true;
pr_info("Tegra cpufreq suspend: setting frequency to %d kHz\n",
freq_table[0].frequency);
tegra_update_cpu_speed(policy, freq_table[0].frequency);
cpufreq_cpu_put(policy);
} else if (event == PM_POST_SUSPEND) {
is_suspended = false;
}
mutex_unlock(&tegra_cpu_lock);
return NOTIFY_OK;
}
static struct notifier_block tegra_cpu_pm_notifier = {
.notifier_call = tegra_pm_notify,
};
static int tegra_cpu_init(struct cpufreq_policy *policy)
{
if (policy->cpu >= NUM_CPUS)
return -EINVAL;
clk_prepare_enable(emc_clk);
clk_prepare_enable(cpu_clk);
cpufreq_frequency_table_cpuinfo(policy, freq_table);
cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
policy->cur = tegra_getspeed(policy->cpu);
target_cpu_speed[policy->cpu] = policy->cur;
/* FIXME: what's the actual transition time? */
policy->cpuinfo.transition_latency = 300 * 1000;
cpumask_copy(policy->cpus, cpu_possible_mask);
if (policy->cpu == 0)
register_pm_notifier(&tegra_cpu_pm_notifier);
return 0;
}
static int tegra_cpu_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_cpuinfo(policy, freq_table);
clk_disable_unprepare(emc_clk);
return 0;
}
static struct freq_attr *tegra_cpufreq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver tegra_cpufreq_driver = {
.verify = tegra_verify_speed,
.target = tegra_target,
.get = tegra_getspeed,
.init = tegra_cpu_init,
.exit = tegra_cpu_exit,
.name = "tegra",
.attr = tegra_cpufreq_attr,
};
static int __init tegra_cpufreq_init(void)
{
cpu_clk = clk_get_sys(NULL, "cpu");
if (IS_ERR(cpu_clk))
return PTR_ERR(cpu_clk);
pll_x_clk = clk_get_sys(NULL, "pll_x");
if (IS_ERR(pll_x_clk))
return PTR_ERR(pll_x_clk);
pll_p_clk = clk_get_sys(NULL, "pll_p_cclk");
if (IS_ERR(pll_p_clk))
return PTR_ERR(pll_p_clk);
emc_clk = clk_get_sys("cpu", "emc");
if (IS_ERR(emc_clk)) {
clk_put(cpu_clk);
return PTR_ERR(emc_clk);
}
return cpufreq_register_driver(&tegra_cpufreq_driver);
}
static void __exit tegra_cpufreq_exit(void)
{
cpufreq_unregister_driver(&tegra_cpufreq_driver);
clk_put(emc_clk);
clk_put(cpu_clk);
}
MODULE_AUTHOR("Colin Cross <ccross@android.com>");
MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
MODULE_LICENSE("GPL");
module_init(tegra_cpufreq_init);
module_exit(tegra_cpufreq_exit);
