Re: [PATCH v2 14/16] cpufreq: Add cpufreq driver for Tegra124

[Rafael J. Wysocki]

On Monday, July 21, 2014 06:39:00 PM Tuomas Tynkkynen wrote:
> Add a new cpufreq driver for Tegra124. Instead of using the PLLX as
> the CPU clocksource, switch immediately to the DFLL. It allows the use
> of higher clock rates, and will automatically scale the CPU voltage as
> well. Besides the CPU clocksource switch, we let the cpufreq-cpu0 driver
> for all the cpufreq operations.
> 
> This driver also relies on the DFLL driver to fill the OPP table for the
> CPU0 device, so that the cpufreq-cpu0 driver knows what frequencies to
> use.
> 
> This driver is a completely independent of the old cpufreq driver
> (tegra-cpufreq), which is only used on Tegra20.
> 
> Signed-off-by: Tuomas Tynkkynen <ttynkkynen@xxxxxxxxxx>

I'm leaving this to Viresh.  If he AKCs it for you, please feel free to push
this through whatever tree you think is appropriate.

> ---
> v2 changes:
>     - use the cpufreq-cpu0 driver
> 
>  drivers/cpufreq/Kconfig.arm        |   1 +
>  drivers/cpufreq/Makefile           |   1 +
>  drivers/cpufreq/tegra124-cpufreq.c | 169 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 171 insertions(+)
>  create mode 100644 drivers/cpufreq/tegra124-cpufreq.c
> 
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 7364a53..df3c73e 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -244,6 +244,7 @@ config ARM_SPEAR_CPUFREQ
>  config ARM_TEGRA_CPUFREQ
>  	bool "TEGRA CPUFreq support"
>  	depends on ARCH_TEGRA
> +	depends on GENERIC_CPUFREQ_CPU0
>  	default y
>  	help
>  	  This adds the CPUFreq driver support for TEGRA SOCs.
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index db6d9a2..3437d24 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_ARM_SA1100_CPUFREQ)	+= sa1100-cpufreq.o
>  obj-$(CONFIG_ARM_SA1110_CPUFREQ)	+= sa1110-cpufreq.o
>  obj-$(CONFIG_ARM_SPEAR_CPUFREQ)		+= spear-cpufreq.o
>  obj-$(CONFIG_ARM_TEGRA_CPUFREQ)		+= tegra-cpufreq.o
> +obj-$(CONFIG_ARM_TEGRA_CPUFREQ)		+= tegra124-cpufreq.o
>  obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ)	+= vexpress-spc-cpufreq.o
>  
>  ##################################################################################
> diff --git a/drivers/cpufreq/tegra124-cpufreq.c b/drivers/cpufreq/tegra124-cpufreq.c
> new file mode 100644
> index 0000000..65ff428
> --- /dev/null
> +++ b/drivers/cpufreq/tegra124-cpufreq.c
> @@ -0,0 +1,169 @@
> +/*
> + * Tegra 124 cpufreq driver
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
> +
> +#include <linux/clk.h>
> +#include <linux/cpufreq.h>
> +#include <linux/cpu.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> +#include <linux/types.h>
> +
> +static struct cpufreq_frequency_table *freq_table;
> +
> +static struct device *cpu_dev;
> +static struct clk *cpu_clk;
> +static struct clk *pllp_clk;
> +static struct clk *pllx_clk;
> +static struct clk *dfll_clk;
> +
> +static int tegra124_cpu_switch_to_dfll(void)
> +{
> +	struct clk *original_cpu_clk_parent;
> +	unsigned long rate;
> +	struct dev_pm_opp *opp;
> +	int ret;
> +
> +	rate = clk_get_rate(cpu_clk);
> +	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &rate);
> +	if (IS_ERR(opp))
> +		return PTR_ERR(opp);
> +
> +	ret = clk_set_rate(dfll_clk, rate);
> +	if (ret)
> +		return ret;
> +
> +	original_cpu_clk_parent = clk_get_parent(cpu_clk);
> +	clk_set_parent(cpu_clk, pllp_clk);
> +	if (ret)
> +		return ret;
> +
> +	ret = clk_prepare_enable(dfll_clk);
> +	if (ret)
> +		goto out_switch_to_original_parent;
> +
> +	clk_set_parent(cpu_clk, dfll_clk);
> +
> +	return 0;
> +
> +out_switch_to_original_parent:
> +	clk_set_parent(cpu_clk, original_cpu_clk_parent);
> +
> +	return ret;
> +}
> +
> +static struct platform_device_info cpufreq_cpu0_devinfo = {
> +	.name = "cpufreq-cpu0",
> +};
> +
> +static int tegra124_cpufreq_probe(struct platform_device *pdev)
> +{
> +	int ret;
> +
> +	cpu_dev = get_cpu_device(0);
> +	if (!cpu_dev)
> +		return -ENODEV;
> +
> +	cpu_clk = of_clk_get_by_name(cpu_dev->of_node, "cpu_g");
> +	if (IS_ERR(cpu_clk))
> +		return PTR_ERR(cpu_clk);
> +
> +	dfll_clk = of_clk_get_by_name(cpu_dev->of_node, "dfll");
> +	if (IS_ERR(dfll_clk)) {
> +		ret = PTR_ERR(dfll_clk);
> +		goto out_put_cpu_clk;
> +	}
> +
> +	pllx_clk = of_clk_get_by_name(cpu_dev->of_node, "pll_x");
> +	if (IS_ERR(pllx_clk)) {
> +		ret = PTR_ERR(pllx_clk);
> +		goto out_put_dfll_clk;
> +	}
> +
> +	pllp_clk = of_clk_get_by_name(cpu_dev->of_node, "pll_p");
> +	if (IS_ERR(pllp_clk)) {
> +		ret = PTR_ERR(pllp_clk);
> +		goto out_put_pllx_clk;
> +	}
> +
> +	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
> +	if (ret)
> +		goto out_put_pllp_clk;
> +
> +	ret = tegra124_cpu_switch_to_dfll();
> +	if (ret)
> +		goto out_free_table;
> +
> +	platform_device_register_full(&cpufreq_cpu0_devinfo);
> +
> +	return 0;
> +
> +out_free_table:
> +	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
> +out_put_pllp_clk:
> +	clk_put(pllp_clk);
> +out_put_pllx_clk:
> +	clk_put(pllx_clk);
> +out_put_dfll_clk:
> +	clk_put(dfll_clk);
> +out_put_cpu_clk:
> +	clk_put(cpu_clk);
> +
> +	return ret;
> +}
> +
> +static struct platform_driver tegra124_cpufreq_platdrv = {
> +	.driver = {
> +		.name	= "cpufreq-tegra124",
> +		.owner	= THIS_MODULE,
> +	},
> +	.probe		= tegra124_cpufreq_probe,
> +};
> +
> +static const struct of_device_id soc_of_matches[] = {
> +	{ .compatible = "nvidia,tegra124", },
> +	{}
> +};
> +
> +static int __init tegra_cpufreq_init(void)
> +{
> +	int ret;
> +	struct platform_device *pdev;
> +
> +	if (!of_find_matching_node(NULL, soc_of_matches))
> +		return -ENODEV;
> +
> +	ret = platform_driver_register(&tegra124_cpufreq_platdrv);
> +	if (ret)
> +		return ret;
> +
> +	pdev = platform_device_register_simple("cpufreq-tegra124", -1, NULL, 0);
> +	if (IS_ERR(pdev)) {
> +		platform_driver_unregister(&tegra124_cpufreq_platdrv);
> +		return PTR_ERR(pdev);
> +	}
> +
> +	return 0;
> +}
> +
> +MODULE_AUTHOR("Tuomas Tynkkynen <ttynkkynen@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("cpufreq driver for nVIDIA Tegra124");
> +MODULE_LICENSE("GPLv2");
> +module_init(tegra_cpufreq_init);
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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