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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/clk.h>
#include <linux/cpufreq.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/types.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 },
};
struct tegra20_cpufreq {
struct device *dev;
struct cpufreq_driver driver;
struct clk *cpu_clk;
struct clk *pll_x_clk;
struct clk *pll_p_clk;
bool pll_x_prepared;
};
static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
unsigned int index)
{
struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
unsigned int ifreq = clk_get_rate(cpufreq->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)
{
struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
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(cpufreq->pll_x_clk);
ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
if (ret)
clk_disable_unprepare(cpufreq->pll_x_clk);
else
cpufreq->pll_x_prepared = true;
return ret;
}
static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
{
struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
unsigned long rate = freq_table[index].frequency;
unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
int ret;
/*
* 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(cpufreq->cpu_clk, cpufreq->pll_p_clk);
ret = clk_set_rate(cpufreq->pll_x_clk, rate * 1000);
/* Restore to earlier frequency on error, i.e. pll_x */
if (ret)
dev_err(cpufreq->dev, "Failed to change pll_x to %lu\n", rate);
ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->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 (cpufreq->pll_x_prepared) {
clk_disable_unprepare(cpufreq->pll_x_clk);
cpufreq->pll_x_prepared = false;
}
return ret;
}
static int tegra_cpu_init(struct cpufreq_policy *policy)
{
struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
int ret;
clk_prepare_enable(cpufreq->cpu_clk);
/* FIXME: what's the actual transition time? */
ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
if (ret) {
clk_disable_unprepare(cpufreq->cpu_clk);
return ret;
}
policy->clk = cpufreq->cpu_clk;
policy->suspend_freq = freq_table[0].frequency;
return 0;
}
static int tegra_cpu_exit(struct cpufreq_policy *policy)
{
struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
clk_disable_unprepare(cpufreq->cpu_clk);
return 0;
}
static int tegra20_cpufreq_probe(struct platform_device *pdev)
{
struct tegra20_cpufreq *cpufreq;
int err;
cpufreq = devm_kzalloc(&pdev->dev, sizeof(*cpufreq), GFP_KERNEL);
if (!cpufreq)
return -ENOMEM;
cpufreq->cpu_clk = clk_get_sys(NULL, "cclk");
if (IS_ERR(cpufreq->cpu_clk))
return PTR_ERR(cpufreq->cpu_clk);
cpufreq->pll_x_clk = clk_get_sys(NULL, "pll_x");
if (IS_ERR(cpufreq->pll_x_clk)) {
err = PTR_ERR(cpufreq->pll_x_clk);
goto put_cpu;
}
cpufreq->pll_p_clk = clk_get_sys(NULL, "pll_p");
if (IS_ERR(cpufreq->pll_p_clk)) {
err = PTR_ERR(cpufreq->pll_p_clk);
goto put_pll_x;
}
cpufreq->dev = &pdev->dev;
cpufreq->driver.get = cpufreq_generic_get;
cpufreq->driver.attr = cpufreq_generic_attr;
cpufreq->driver.init = tegra_cpu_init;
cpufreq->driver.exit = tegra_cpu_exit;
cpufreq->driver.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK;
cpufreq->driver.verify = cpufreq_generic_frequency_table_verify;
cpufreq->driver.suspend = cpufreq_generic_suspend;
cpufreq->driver.driver_data = cpufreq;
cpufreq->driver.target_index = tegra_target;
cpufreq->driver.get_intermediate = tegra_get_intermediate;
cpufreq->driver.target_intermediate = tegra_target_intermediate;
snprintf(cpufreq->driver.name, CPUFREQ_NAME_LEN, "tegra");
err = cpufreq_register_driver(&cpufreq->driver);
if (err)
goto put_pll_p;
platform_set_drvdata(pdev, cpufreq);
return 0;
put_pll_p:
clk_put(cpufreq->pll_p_clk);
put_pll_x:
clk_put(cpufreq->pll_x_clk);
put_cpu:
clk_put(cpufreq->cpu_clk);
return err;
}
static int tegra20_cpufreq_remove(struct platform_device *pdev)
{
struct tegra20_cpufreq *cpufreq = platform_get_drvdata(pdev);
cpufreq_unregister_driver(&cpufreq->driver);
clk_put(cpufreq->pll_p_clk);
clk_put(cpufreq->pll_x_clk);
clk_put(cpufreq->cpu_clk);
return 0;
}
static struct platform_driver tegra20_cpufreq_driver = {
.probe = tegra20_cpufreq_probe,
.remove = tegra20_cpufreq_remove,
.driver = {
.name = "tegra20-cpufreq",
},
};
module_platform_driver(tegra20_cpufreq_driver);
MODULE_ALIAS("platform:tegra20-cpufreq");
MODULE_AUTHOR("Colin Cross <ccross@android.com>");
MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
MODULE_LICENSE("GPL");
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