Re: [PATCH 6/6 v4] cpufreq, highbank: add support for highbank cpufreq

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 11/07/2012 12:32 PM, Mark Langsdorf wrote:
> Highbank processors depend on the external ECME to perform voltage
> management based on a requested frequency. Communication between the
> highbank and ECME cores happens over the pl320 IPC channel.
> 
> Signed-off-by: Mark Langsdorf <mark.langsdorf-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
> Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> Cc: Rafael J. Wysocki <rjw-KKrjLPT3xs0@public.gmane.org>
> ---
> Changes from v3
> 	None
> Changes from v2
> 	Changed transition latency binding in code to match documentation
> Changes from v1
>         Added highbank specific Kconfig changes
> 
>  .../bindings/cpufreq/highbank-cpufreq.txt          |  53 +++++
>  arch/arm/Kconfig                                   |   2 +
>  arch/arm/boot/dts/highbank.dts                     |  10 +
>  arch/arm/mach-highbank/Kconfig                     |   2 +
>  drivers/cpufreq/Kconfig.arm                        |  15 ++
>  drivers/cpufreq/Makefile                           |   1 +
>  drivers/cpufreq/highbank-cpufreq.c                 | 229 +++++++++++++++++++++
>  7 files changed, 312 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/cpufreq/highbank-cpufreq.txt
>  create mode 100644 drivers/cpufreq/highbank-cpufreq.c
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/highbank-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/highbank-cpufreq.txt
> new file mode 100644
> index 0000000..3ec2cec
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/cpufreq/highbank-cpufreq.txt
> @@ -0,0 +1,53 @@
> +Highbank cpufreq driver
> +
> +This is cpufreq driver for Calxeda ECX-1000 (highbank) processor. It is based
> +on the generic cpu0 driver and uses a similar format for bindings. Since
> +the EnergyCore Management Engine maintains the voltage based on the
> +frequency, the voltage component of the operating points can be set to any
> +arbitrary values.
> +
> +Both required properties listed below must be defined under node /cpus/cpu@0.
> +
> +Required properties:
> +- operating-points: Refer to Documentation/devicetree/bindings/power/opp.txt
> +  for details
> +- transition-latency: Specify the possible maximum transition latency for clock,
> +  in unit of nanoseconds.
> +
> +Examples:
> +
> +cpus {
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +
> +	cpu@0 {
> +		compatible = "arm,cortex-a9";
> +		reg = <0>;
> +		next-level-cache = <&L2>;
> +		operating-points = <
> +			/* kHz  ignored */
> +			790000  1000000
> +			396000  1000000
> +			198000  1000000
> +		>;
> +		transition-latency = <200000>;
> +	};
> +
> +	cpu@1 {
> +		compatible = "arm,cortex-a9";
> +		reg = <1>;
> +		next-level-cache = <&L2>;
> +	};
> +
> +	cpu@2 {
> +		compatible = "arm,cortex-a9";
> +		reg = <2>;
> +		next-level-cache = <&L2>;
> +	};
> +
> +	cpu@3 {
> +		compatible = "arm,cortex-a9";
> +		reg = <3>;
> +		next-level-cache = <&L2>;
> +	};
> +};
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index ade7e92..4ed0b7b 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -391,6 +391,8 @@ config ARCH_SIRF
>  	select PINCTRL
>  	select PINCTRL_SIRF
>  	select USE_OF
> +	select ARCH_HAS_CPUFREQ
> +	select ARCH_HAS_OPP

This hunk needs to be removed.

>  	help
>  	  Support for CSR SiRFprimaII/Marco/Polo platforms
>  
> diff --git a/arch/arm/boot/dts/highbank.dts b/arch/arm/boot/dts/highbank.dts
> index 0c6fc34..7c4c27d 100644
> --- a/arch/arm/boot/dts/highbank.dts
> +++ b/arch/arm/boot/dts/highbank.dts
> @@ -36,6 +36,16 @@
>  			next-level-cache = <&L2>;
>  			clocks = <&a9pll>;
>  			clock-names = "cpu";
> +			operating-points = <
> +				/* kHz    ignored */
> +				 1300000  1000000
> +				 1200000  1000000
> +				 1100000  1000000
> +				  800000  1000000
> +				  400000  1000000
> +				  200000  1000000
> +			>;
> +			transition-latency = <100000>;
>  		};
>  
>  		cpu@1 {
> diff --git a/arch/arm/mach-highbank/Kconfig b/arch/arm/mach-highbank/Kconfig
> index 0e1d0a4..ee83af6 100644
> --- a/arch/arm/mach-highbank/Kconfig
> +++ b/arch/arm/mach-highbank/Kconfig
> @@ -13,3 +13,5 @@ config ARCH_HIGHBANK
>  	select HAVE_SMP
>  	select SPARSE_IRQ
>  	select USE_OF
> +	select ARCH_HAS_CPUFREQ
> +	select ARCH_HAS_OPP

Sort these alphabetically.

> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 5961e64..bc3ef55 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -76,3 +76,18 @@ config ARM_EXYNOS5250_CPUFREQ
>  	help
>  	  This adds the CPUFreq driver for Samsung EXYNOS5250
>  	  SoC.
> +
> +config ARM_HIGHBANK_CPUFREQ
> +       tristate "Calxeda Highbank-based"
> +       depends on ARCH_HIGHBANK
> +       select CPU_FREQ_TABLE
> +       select HAVE_CLK

ARCH_HIGHBANK already selects this.

> +       select PM_OPP
> +       select OF

And this.

> +       default m
> +       help
> +         This adds the CPUFreq driver for Calxeda Highbank SoC
> +         based boards.
> +
> +         If in doubt, say N.
> +
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 1bc90e1..9e8f12a 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -50,6 +50,7 @@ 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_OMAP2PLUS_CPUFREQ)     += omap-cpufreq.o
> +obj-$(CONFIG_ARM_HIGHBANK_CPUFREQ)	+= highbank-cpufreq.o
>  
>  ##################################################################################
>  # PowerPC platform drivers
> diff --git a/drivers/cpufreq/highbank-cpufreq.c b/drivers/cpufreq/highbank-cpufreq.c
> new file mode 100644
> index 0000000..a167073
> --- /dev/null
> +++ b/drivers/cpufreq/highbank-cpufreq.c
> @@ -0,0 +1,229 @@
> +/*
> + * Copyright (C) 2012 Calxeda, Inc.
> + *
> + * derived from cpufreq-cpu0 by Freescale Semiconductor
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
> +
> +#include <linux/clk.h>
> +#include <linux/cpu.h>
> +#include <linux/cpufreq.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/opp.h>
> +#include <linux/slab.h>
> +#include <asm/pl320-ipc.h>
> +
> +#define HB_CPUFREQ_CHANGE_NOTE 0x80000001
> +
> +static unsigned int transition_latency;
> +
> +static struct device *cpu_dev;
> +static struct clk *cpu_clk;
> +static struct cpufreq_frequency_table *freq_table;
> +
> +static int hb_verify_speed(struct cpufreq_policy *policy)
> +{
> +	return cpufreq_frequency_table_verify(policy, freq_table);
> +}
> +
> +static unsigned int hb_get_speed(unsigned int cpu)
> +{
> +	return clk_get_rate(cpu_clk) / 1000;
> +}
> +
> +static int hb_voltage_change(unsigned int freq)
> +{
> +	int i;
> +	u32 msg[7];
> +
> +	msg[0] = HB_CPUFREQ_CHANGE_NOTE;
> +	msg[1] = freq / 1000;
> +	for (i = 2; i < 7; i++)
> +		msg[i] = 0;
> +
> +	return ipc_call_slow(msg);
> +}
> +
> +static int hb_set_target(struct cpufreq_policy *policy,
> +			   unsigned int target_freq, unsigned int relation)
> +{
> +	struct cpufreq_freqs freqs;
> +	unsigned long freq_Hz;
> +	unsigned int index, cpu;
> +	int ret;
> +
> +	ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
> +					     relation, &index);
> +	if (ret) {
> +		pr_err("failed to match target freqency %d: %d\n",
> +		       target_freq, ret);
> +		return ret;
> +	}
> +
> +	freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
> +	if (freq_Hz < 0)
> +		freq_Hz = freq_table[index].frequency * 1000;
> +	freqs.new = freq_Hz / 1000;
> +	freqs.old = clk_get_rate(cpu_clk) / 1000;
> +
> +	if (freqs.old == freqs.new)
> +		return 0;
> +
> +	for_each_online_cpu(cpu) {
> +		freqs.cpu = cpu;
> +		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
> +	}
> +
> +	pr_debug("%u MHz --> %u MHz\n", freqs.old / 1000, freqs.new / 1000);
> +
> +	/* scaling up?  scale voltage before frequency */
> +	if (freqs.new > freqs.old) {
> +		ret = hb_voltage_change(freqs.new);
> +		if (ret) {
> +			freqs.new = freqs.old;
> +			return -EAGAIN;
> +		}
> +	}
> +
> +	ret = clk_set_rate(cpu_clk, freqs.new * 1000);
> +	if (ret) {
> +		pr_err("failed to set clock rate: %d\n", ret);
> +		hb_voltage_change(freqs.old);
> +		return ret;
> +	}
> +
> +	/* scaling down?  scale voltage after frequency */
> +	if (freqs.new < freqs.old) {
> +		ret = hb_voltage_change(freqs.new);
> +		if (ret) {
> +			if (clk_set_rate(cpu_clk, freqs.old * 1000))
> +				pr_err("also failed to reset freq\n");
> +			freqs.new = freqs.old;
> +			return -EAGAIN;
> +		}
> +	}
> +
> +	for_each_online_cpu(cpu) {
> +		freqs.cpu = cpu;
> +		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
> +	}
> +
> +	return 0;
> +}
> +
> +static int hb_cpufreq_init(struct cpufreq_policy *policy)
> +{
> +	int ret;
> +
> +	if (policy->cpu != 0)
> +		return -EINVAL;
> +
> +	ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
> +	if (ret) {
> +		pr_err("invalid frequency table: %d\n", ret);
> +		return ret;
> +	}
> +
> +	policy->cpuinfo.transition_latency = transition_latency;
> +	policy->cur = clk_get_rate(cpu_clk) / 1000;
> +
> +	policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
> +	cpumask_setall(policy->cpus);
> +
> +	cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
> +
> +	return 0;
> +}
> +
> +static int hb_cpufreq_exit(struct cpufreq_policy *policy)
> +{
> +	cpufreq_frequency_table_put_attr(policy->cpu);
> +
> +	return 0;
> +}
> +
> +static struct freq_attr *hb_cpufreq_attr[] = {
> +	&cpufreq_freq_attr_scaling_available_freqs,
> +	NULL,
> +};
> +
> +static struct cpufreq_driver hb_cpufreq_driver = {
> +	.flags = CPUFREQ_STICKY,
> +	.verify = hb_verify_speed,
> +	.target = hb_set_target,
> +	.get = hb_get_speed,
> +	.init = hb_cpufreq_init,
> +	.exit = hb_cpufreq_exit,
> +	.name = "highbank-cpufreq",
> +	.attr = hb_cpufreq_attr,
> +};
> +
> +static int __devinit hb_cpufreq_driver_init(void)
> +{
> +	struct device_node *np;
> +	int ret;
> +
> +	np = of_find_node_by_path("/cpus/cpu@0");
> +	if (!np) {
> +		pr_err("failed to find highbank cpufreq node\n");
> +		return -ENOENT;
> +	}
> +
> +	cpu_dev = get_cpu_device(0);
> +	if (!cpu_dev) {
> +		pr_err("failed to get highbank cpufreq device\n");
> +		ret = -ENODEV;
> +		goto out_put_node;
> +	}
> +
> +	cpu_dev->of_node = np;
> +
> +	cpu_clk = clk_get(cpu_dev, NULL);
> +	if (IS_ERR(cpu_clk)) {
> +		ret = PTR_ERR(cpu_clk);
> +		pr_err("failed to get cpu0 clock: %d\n", ret);
> +		goto out_put_node;
> +	}
> +
> +	ret = of_init_opp_table(cpu_dev);
> +	if (ret) {
> +		pr_err("failed to init OPP table: %d\n", ret);
> +		goto out_put_node;
> +	}
> +
> +	ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
> +	if (ret) {
> +		pr_err("failed to init cpufreq table: %d\n", ret);
> +		goto out_put_node;
> +	}
> +
> +	if (of_property_read_u32(np, "transition-latency", &transition_latency))
> +		transition_latency = CPUFREQ_ETERNAL;
> +
> +	ret = cpufreq_register_driver(&hb_cpufreq_driver);
> +	if (ret) {
> +		pr_err("failed register driver: %d\n", ret);
> +		goto out_free_table;
> +	}
> +
> +	of_node_put(np);
> +	return 0;
> +
> +out_free_table:
> +	opp_free_cpufreq_table(cpu_dev, &freq_table);
> +out_put_node:
> +	of_node_put(np);
> +	return ret;
> +}
> +late_initcall(hb_cpufreq_driver_init);
> +
> +MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>");
> +MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
> +MODULE_LICENSE("GPL");
>