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/*
* 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>
static struct cpufreq_frequency_table freq_table[] = {
{ .frequency = 216000 },
{ .frequency = 312000 },
{ .frequency = 456000 },
{ .frequency = 608000 },
{ .frequency = 760000 },
{ .frequency = 816000 },
{ .frequency = 912000 },
{ .frequency = 1000000 },
{ .frequency = 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 bool pll_x_prepared;
static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
unsigned int index)
{
unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
/*
* Don't switch to intermediate freq if:
* - we are already at it, i.e. policy->cur == ifreq
* - index corresponds to ifreq
*/
if ((freq_table[index].frequency == ifreq) || (policy->cur == ifreq))
return 0;
return ifreq;
}
static int tegra_target_intermediate(struct cpufreq_policy *policy,
unsigned int index)
{
int ret;
/*
* Take an extra reference to the main pll so it doesn't turn
* off when we move the cpu off of it as enabling it again while we
* switch to it from tegra_target() would take additional time.
*
* When target-freq is equal to intermediate freq we don't need to
* switch to an intermediate freq and so this routine isn't called.
* Also, we wouldn't be using pll_x anymore and must not take extra
* reference to it, as it can be disabled now to save some power.
*/
clk_prepare_enable(pll_x_clk);
ret = clk_set_parent(cpu_clk, pll_p_clk);
if (ret)
clk_disable_unprepare(pll_x_clk);
else
pll_x_prepared = true;
return ret;
}
static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
{
unsigned long rate = freq_table[index].frequency;
unsigned int ifreq = clk_get_rate(pll_p_clk) / 1000;
int ret = 0;
/*
* 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 */
/*
* target freq == pll_p, don't need to take extra reference to pll_x_clk
* as it isn't used anymore.
*/
if (rate == ifreq)
return clk_set_parent(cpu_clk, pll_p_clk);
ret = clk_set_rate(pll_x_clk, rate * 1000);
/* Restore to earlier frequency on error, i.e. pll_x */
if (ret)
pr_err("Failed to change pll_x to %lu\n", rate);
ret = clk_set_parent(cpu_clk, pll_x_clk);
/* This shouldn't fail while changing or restoring */
WARN_ON(ret);
/*
* Drop count to pll_x clock only if we switched to intermediate freq
* earlier while transitioning to a target frequency.
*/
if (pll_x_prepared) {
clk_disable_unprepare(pll_x_clk);
pll_x_prepared = false;
}
return ret;
}
static int tegra_cpu_init(struct cpufreq_policy *policy)
{
int ret;
if (policy->cpu >= NUM_CPUS)
return -EINVAL;
clk_prepare_enable(emc_clk);
clk_prepare_enable(cpu_clk);
/* FIXME: what's the actual transition time? */
ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
if (ret) {
clk_disable_unprepare(cpu_clk);
clk_disable_unprepare(emc_clk);
return ret;
}
policy->clk = cpu_clk;
policy->suspend_freq = freq_table[0].frequency;
return 0;
}
static int tegra_cpu_exit(struct cpufreq_policy *policy)
{
clk_disable_unprepare(cpu_clk);
clk_disable_unprepare(emc_clk);
return 0;
}
static struct cpufreq_driver tegra_cpufreq_driver = {
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.get_intermediate = tegra_get_intermediate,
.target_intermediate = tegra_target_intermediate,
.target_index = tegra_target,
.get = cpufreq_generic_get,
.init = tegra_cpu_init,
.exit = tegra_cpu_exit,
.name = "tegra",
.attr = cpufreq_generic_attr,
.suspend = cpufreq_generic_suspend,
};
static int __init tegra_cpufreq_init(void)
{
cpu_clk = clk_get_sys(NULL, "cclk");
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");
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);
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