Re: [PATCH v4 1/3] cpufreq: kirkwood: Add a cpufreq driver for Marvell Kirkwood SoCs

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On Fri, Feb 01, 2013 at 03:31:33PM +0100, Andrew Lunn wrote:
> 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: Andrew Lunn <andrew@xxxxxxx>
> Acked-by: Jason Cooper <jason@xxxxxxxxxxxxxx>
> ---
> 
> To be commited by: Rafael J. Wysocki
> 
>  drivers/clk/mvebu/clk-gating-ctrl.c |    1 +
>  drivers/cpufreq/Kconfig.arm         |    6 +
>  drivers/cpufreq/Makefile            |    1 +
>  drivers/cpufreq/kirkwood-cpufreq.c  |  277 +++++++++++++++++++++++++++++++++++
>  4 files changed, 285 insertions(+)
>  create mode 100644 drivers/cpufreq/kirkwood-cpufreq.c
> 
> diff --git a/drivers/clk/mvebu/clk-gating-ctrl.c b/drivers/clk/mvebu/clk-gating-ctrl.c
> index 8fa5408..ebf141d 100644
> --- a/drivers/clk/mvebu/clk-gating-ctrl.c
> +++ b/drivers/clk/mvebu/clk-gating-ctrl.c
> @@ -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 },
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index a0b3661..80c8229 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -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_SPEAR_CPUFREQ
>  	bool "SPEAr CPUFreq support"
>  	depends on PLAT_SPEAR
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index fadc4d4..39a0ffe 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -50,6 +50,7 @@ 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
>  
> diff --git a/drivers/cpufreq/kirkwood-cpufreq.c b/drivers/cpufreq/kirkwood-cpufreq.c
> new file mode 100644
> index 0000000..8923689
> --- /dev/null
> +++ b/drivers/cpufreq/kirkwood-cpufreq.c
> @@ -0,0 +1,277 @@
> +/*
> + *	kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
> + *
> + *	Copyright (C) 2013 Andrew Lunn <andrew@xxxxxxx>
> + *
> + *	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>

Why do you need this header?

> +#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_core = of_find_compatible_node(
> +		NULL, NULL, "marvell,kirkwood-core-clock");
> +	struct device_node *np_gating = of_find_compatible_node(
> +		NULL, NULL, "marvell,kirkwood-gating-clock");
> +	struct of_phandle_args clkspec;
> +	struct resource *res;
> +	int err;
> +
> +	if (!np_core || !np_gating) {
> +		if (np_core)
> +			of_node_put(np_core);
> +		if (np_gating)
> +			of_node_put(np_gating);
> +		return -ENODEV;
> +	}
> +	
> +	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;
> +	}
> +
> +	clkspec.np = np_core;
> +	clkspec.args_count = 1;
> +	clkspec.args[0] = 1;
> +
> +	priv.cpu_clk = of_clk_get_from_provider(&clkspec);

Again, clk client is not really supposed to call this.  Having a node
in device tree consuming all the clocks you need and attaching the
node to pdev->dev.of_node will have devm_clk_get just work for you.
The node could reasonably be /cpus/cpu@0.

Shawn

> +	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;
> +
> +	clkspec.args[0] = 3;
> +	priv.ddr_clk = of_clk_get_from_provider(&clkspec);
> +	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;
> +
> +	clkspec.np = np_gating;
> +	clkspec.args[0] = 11;
> +	priv.powersave_clk = of_clk_get_from_provider(&clkspec);
> +	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_core);
> +	np_core = NULL;
> +	of_node_put(np_gating);
> +	np_gating = 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_core);
> +	of_node_put(np_gating);
> +
> +	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@xxxxxxx");
> +MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
> +MODULE_ALIAS("platform:kirkwood-cpufreq");
> -- 
> 1.7.10.4
> 
> 
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