linux/drivers/cpufreq/kirkwood-cpufreq.c
Mike Turquette 105299381d cpufreq: kirkwood: use the powersave multiplexer
The powersave clock acts like a multiplexer for the cpu, selecting
either the clock signal derived from the cpu pll or from the ddr clock.
This patch changes powersave from a gate clock to a mux clock to better
reflect this behavior.

This is a cleaner approach whereby the frequency of the cpu always
matches the rate of powersave_clk. The cpufreq driver for the kirkwood
platform no longer must parse this behavior out of various calls to
clk_enable and clk_disable, but can instead simply select the parent cpu
it wants when changing rate. Likewise when requesting the cpu rate we
need only query powersave_clk's rate through the usual call to
clk_get_rate.

The new clock data and corresponding changes to the cpufreq driver are
combined into this single commit to avoid a git bisect issue where this
cpufreq driver fails to work properly between the commit that updates
the kirkwood clock driver and the commit that changes how the cpufreq
driver uses that clock.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
2014-09-02 15:02:54 -07:00

196 lines
4.7 KiB
C

/*
* 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/cpufreq.h>
#include <linux/of_device.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[] = {
{0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
{0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
{0, 0, CPUFREQ_TABLE_END},
};
static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
{
return clk_get_rate(priv.powersave_clk) / 1000;
}
static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
unsigned int index)
{
unsigned int state = kirkwood_freq_table[index].driver_data;
unsigned long reg;
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_set_parent(priv.powersave_clk, priv.cpu_clk);
break;
case STATE_DDR_FREQ:
clk_set_parent(priv.powersave_clk, priv.ddr_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();
return 0;
}
/* Module init and exit code */
static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
}
static struct cpufreq_driver kirkwood_cpufreq_driver = {
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.get = kirkwood_cpufreq_get_cpu_frequency,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = kirkwood_cpufreq_target,
.init = kirkwood_cpufreq_cpu_init,
.name = "kirkwood-cpufreq",
.attr = cpufreq_generic_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);
priv.base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(priv.base))
return PTR_ERR(priv.base);
np = of_cpu_device_node_get(0);
if (!np) {
dev_err(&pdev->dev, "failed to get cpu device node\n");
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_enable(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");