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/*
* kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
*
* Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/cpufreq.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <asm/proc-fns.h>
#define CPU_SW_INT_BLK BIT(28)
static struct priv
{
struct clk *cpu_clk;
struct clk *ddr_clk;
struct clk *powersave_clk;
struct device *dev;
void __iomem *base;
} priv;
#define STATE_CPU_FREQ 0x01
#define STATE_DDR_FREQ 0x02
/*
* Kirkwood can swap the clock to the CPU between two clocks:
*
* - cpu clk
* - ddr clk
*
* The frequencies are set at runtime before registering this *
* table.
*/
static struct cpufreq_frequency_table kirkwood_freq_table[] = {
{STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
{STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
{0, CPUFREQ_TABLE_END},
};
static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
{
if (__clk_is_enabled(priv.powersave_clk))
return kirkwood_freq_table[1].frequency;
return kirkwood_freq_table[0].frequency;
}
static void kirkwood_cpufreq_set_cpu_state(struct cpufreq_policy *policy,
unsigned int index)
{
struct cpufreq_freqs freqs;
unsigned int state = kirkwood_freq_table[index].index;
unsigned long reg;
freqs.old = kirkwood_cpufreq_get_cpu_frequency(0);
freqs.new = kirkwood_freq_table[index].frequency;
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n",
kirkwood_freq_table[index].frequency);
dev_dbg(priv.dev, "old frequency was %i KHz\n",
kirkwood_cpufreq_get_cpu_frequency(0));
if (freqs.old != freqs.new) {
local_irq_disable();
/* Disable interrupts to the CPU */
reg = readl_relaxed(priv.base);
reg |= CPU_SW_INT_BLK;
writel_relaxed(reg, priv.base);
switch (state) {
case STATE_CPU_FREQ:
clk_disable(priv.powersave_clk);
break;
case STATE_DDR_FREQ:
clk_enable(priv.powersave_clk);
break;
}
/* Wait-for-Interrupt, while the hardware changes frequency */
cpu_do_idle();
/* Enable interrupts to the CPU */
reg = readl_relaxed(priv.base);
reg &= ~CPU_SW_INT_BLK;
writel_relaxed(reg, priv.base);
local_irq_enable();
}
cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
};
static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, kirkwood_freq_table);
}
static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
unsigned int index = 0;
if (cpufreq_frequency_table_target(policy, kirkwood_freq_table,
target_freq, relation, &index))
return -EINVAL;
kirkwood_cpufreq_set_cpu_state(policy, index);
return 0;
}
/* Module init and exit code */
static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
int result;
/* cpuinfo and default policy values */
policy->cpuinfo.transition_latency = 5000; /* 5uS */
policy->cur = kirkwood_cpufreq_get_cpu_frequency(0);
result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table);
if (result)
return result;
cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu);
return 0;
}
static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_put_attr(policy->cpu);
return 0;
}
static struct freq_attr *kirkwood_cpufreq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver kirkwood_cpufreq_driver = {
.get = kirkwood_cpufreq_get_cpu_frequency,
.verify = kirkwood_cpufreq_verify,
.target = kirkwood_cpufreq_target,
.init = kirkwood_cpufreq_cpu_init,
.exit = kirkwood_cpufreq_cpu_exit,
.name = "kirkwood-cpufreq",
.owner = THIS_MODULE,
.attr = kirkwood_cpufreq_attr,
};
static int kirkwood_cpufreq_probe(struct platform_device *pdev)
{
struct device_node *np;
struct resource *res;
int err;
priv.dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "Cannot get memory resource\n");
return -ENODEV;
}
priv.base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(priv.base))
return PTR_ERR(priv.base);
np = of_find_node_by_path("/cpus/cpu@0");
if (!np)
return -ENODEV;
priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
if (IS_ERR(priv.cpu_clk)) {
dev_err(priv.dev, "Unable to get cpuclk");
return PTR_ERR(priv.cpu_clk);
}
clk_prepare_enable(priv.cpu_clk);
kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
if (IS_ERR(priv.ddr_clk)) {
dev_err(priv.dev, "Unable to get ddrclk");
err = PTR_ERR(priv.ddr_clk);
goto out_cpu;
}
clk_prepare_enable(priv.ddr_clk);
kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
priv.powersave_clk = of_clk_get_by_name(np, "powersave");
if (IS_ERR(priv.powersave_clk)) {
dev_err(priv.dev, "Unable to get powersave");
err = PTR_ERR(priv.powersave_clk);
goto out_ddr;
}
clk_prepare(priv.powersave_clk);
of_node_put(np);
np = NULL;
err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
if (!err)
return 0;
dev_err(priv.dev, "Failed to register cpufreq driver");
clk_disable_unprepare(priv.powersave_clk);
out_ddr:
clk_disable_unprepare(priv.ddr_clk);
out_cpu:
clk_disable_unprepare(priv.cpu_clk);
of_node_put(np);
return err;
}
static int kirkwood_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
clk_disable_unprepare(priv.powersave_clk);
clk_disable_unprepare(priv.ddr_clk);
clk_disable_unprepare(priv.cpu_clk);
return 0;
}
static struct platform_driver kirkwood_cpufreq_platform_driver = {
.probe = kirkwood_cpufreq_probe,
.remove = kirkwood_cpufreq_remove,
.driver = {
.name = "kirkwood-cpufreq",
.owner = THIS_MODULE,
},
};
module_platform_driver(kirkwood_cpufreq_platform_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
MODULE_ALIAS("platform:kirkwood-cpufreq");
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