Commit 2a4bd9f0 authored by Andrew Lunn's avatar Andrew Lunn Committed by Rafael J. Wysocki
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cpufreq: kirkwood: Add a cpufreq driver for Marvell Kirkwood SoCs 



The Marvell Kirkwood SoCs have simple cpufreq support in hardware. The
CPU can either use the a high speed cpu clock, or the slower DDR
clock. Add a driver to swap between these two clock sources.

Signed-off-by: default avatarAndrew Lunn <andrew@lunn.ch>
Acked-by: default avatarJason Cooper <jason@lakedaemon.net>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 93f0822d

Documentation/devicetree/bindings/arm/kirkwood.txt

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Marvell Kirkwood Platforms Device Tree Bindings

-----------------------------------------------



Boards with a SoC of the Marvell Kirkwood

shall have the following property:



Required root node property:



compatible: must contain "marvell,kirkwood";



In order to support the kirkwood cpufreq driver, there must be a node

cpus/cpu@0 with three clocks, "cpu_clk", "ddrclk" and "powersave",

where the "powersave" clock is a gating clock used to switch the CPU

between the "cpu_clk" and the "ddrclk".



Example:



	cpus {

		#address-cells = <1>;

		#size-cells = <0>;



		cpu@0 {

		      device_type = "cpu";

		      compatible = "marvell,sheeva-88SV131";

		      clocks = <&core_clk 1>, <&core_clk 3>, <&gate_clk 11>;

		      clock-names = "cpu_clk", "ddrclk", "powersave";

		};

drivers/clk/mvebu/clk-gating-ctrl.c

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@@ -193,6 +193,7 @@ static const struct mvebu_soc_descr __initconst kirkwood_gating_descr[] = { 
	{ "runit", NULL, 7 },

	{ "xor0", NULL, 8 },

	{ "audio", NULL, 9 },

	{ "powersave", "cpuclk", 11 },

	{ "sata0", NULL, 14 },

	{ "sata1", NULL, 15 },

	{ "xor1", NULL, 16 },

drivers/cpufreq/Kconfig.arm

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@@ -77,6 +77,12 @@ config ARM_EXYNOS5250_CPUFREQ 
	  This adds the CPUFreq driver for Samsung EXYNOS5250

	  SoC.



config ARM_KIRKWOOD_CPUFREQ

	def_bool ARCH_KIRKWOOD && OF

	help

	  This adds the CPUFreq driver for Marvell Kirkwood

	  SoCs.



config ARM_IMX6Q_CPUFREQ

	tristate "Freescale i.MX6Q cpufreq support"

	depends on SOC_IMX6Q

drivers/cpufreq/Makefile

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@@ -52,6 +52,7 @@ obj-$(CONFIG_ARM_EXYNOS_CPUFREQ) += exynos-cpufreq.o 
obj-$(CONFIG_ARM_EXYNOS4210_CPUFREQ)	+= exynos4210-cpufreq.o

obj-$(CONFIG_ARM_EXYNOS4X12_CPUFREQ)	+= exynos4x12-cpufreq.o

obj-$(CONFIG_ARM_EXYNOS5250_CPUFREQ)	+= exynos5250-cpufreq.o

obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ)	+= kirkwood-cpufreq.o

obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ)	+= omap-cpufreq.o

obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o

obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ)	+= highbank-cpufreq.o

drivers/cpufreq/kirkwood-cpufreq.c

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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(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;

	freqs.cpu = 0; /* Kirkwood is UP */



	cpufreq_notify_transition(&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(&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(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_request_and_ioremap(&pdev->dev, res);

	if (!priv.base) {

		dev_err(&pdev->dev, "Cannot ioremap\n");

		return -EADDRNOTAVAIL;

	}



	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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