Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH 4/4] cpufreq: add driver for Raspbery Pi
To:     Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Viresh Kumar <viresh.kumar@linaro.org>
Cc:     linux-arm-kernel@lists.infradead.org, f.fainelli@gmail.com,
        ptesarik@suse.com, sboyd@kernel.org, mturquette@baylibre.com,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
        eric@anholt.net, bcm-kernel-feedback-list@broadcom.com,
        linux-rpi-kernel@lists.infradead.org, linux-clk@vger.kernel.org,
        mbrugger@suse.de, ssuloev@orpaltech.com
References: <20190604173223.4229-1-nsaenzjulienne@suse.de>
 <20190604173223.4229-5-nsaenzjulienne@suse.de>
From:   Stefan Wahren <wahrenst@gmx.net>
Message-ID: <e59ad4c7-504a-a16e-a678-987ab95ed6ea@gmx.net>
Date:   Wed, 5 Jun 2019 13:15:07 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.0
MIME-Version: 1.0
In-Reply-To: <20190604173223.4229-5-nsaenzjulienne@suse.de>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Nicolas,

Am 04.06.19 um 19:32 schrieb Nicolas Saenz Julienne:
> Raspberry Pi's firmware offers and interface though which update it's
> performance requirements. It allows us to request for specific runtime
> frequencies, which the firmware might or might not respect, depending on
> the firmware configuration and thermals.
>
> As the maximum and minimum frequencies are configurable in the firmware
> there is no way to know in advance their values. So the Raspberry Pi
> cpufreq driver queries them, builds an opp frequency table to then
> launch cpufreq-dt.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
>
> Changes since RFC:
>   - Alphabetically ordered relevant stuff
>   - Updated Kconfig to select firmware interface
>   - Correctly unref clk_dev after use
>   - Remove all opps on failure
>   - Remove use of dev_pm_opp_set_sharing_cpus()
>
>  drivers/cpufreq/Kconfig.arm           |  8 +++
>  drivers/cpufreq/Makefile              |  1 +
>  drivers/cpufreq/raspberrypi-cpufreq.c | 84 +++++++++++++++++++++++++++
>  3 files changed, 93 insertions(+)
>  create mode 100644 drivers/cpufreq/raspberrypi-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index f8129edc145e..556d432cc826 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -133,6 +133,14 @@ config ARM_QCOM_CPUFREQ_HW
>  	  The driver implements the cpufreq interface for this HW engine.
>  	  Say Y if you want to support CPUFreq HW.
>
> +config ARM_RASPBERRYPI_CPUFREQ
> +	tristate "Raspberry Pi cpufreq support"
> +	select RASPBERRYPI_FIRMWARE
> +	help
> +	  This adds the CPUFreq driver for Raspberry Pi
For the next version please add one patch which enables the driver and
its dependencies for bcm2835_defconfig and multi_v7_defconfig and
another patch to build as a module for arm64/defconfig.
> +
> +	  If in doubt, say N.
> +
>  config ARM_S3C_CPUFREQ
>  	bool
>  	help
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 689b26c6f949..121c1acb66c0 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -64,6 +64,7 @@ obj-$(CONFIG_ARM_PXA2xx_CPUFREQ)	+=3D pxa2xx-cpufreq.o
>  obj-$(CONFIG_PXA3xx)			+=3D pxa3xx-cpufreq.o
>  obj-$(CONFIG_ARM_QCOM_CPUFREQ_HW)	+=3D qcom-cpufreq-hw.o
>  obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO)	+=3D qcom-cpufreq-kryo.o
> +obj-$(CONFIG_ARM_RASPBERRYPI_CPUFREQ) 	+=3D raspberrypi-cpufreq.o
>  obj-$(CONFIG_ARM_S3C2410_CPUFREQ)	+=3D s3c2410-cpufreq.o
>  obj-$(CONFIG_ARM_S3C2412_CPUFREQ)	+=3D s3c2412-cpufreq.o
>  obj-$(CONFIG_ARM_S3C2416_CPUFREQ)	+=3D s3c2416-cpufreq.o
> diff --git a/drivers/cpufreq/raspberrypi-cpufreq.c b/drivers/cpufreq/ras=
pberrypi-cpufreq.c
> new file mode 100644
> index 000000000000..2b3a195a9d37
> --- /dev/null
> +++ b/drivers/cpufreq/raspberrypi-cpufreq.c
> @@ -0,0 +1,84 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Raspberry Pi cpufreq driver
> + *
> + * Copyright (C) 2019, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/cpu.h>
> +#include <linux/cpufreq.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> +
> +static const struct of_device_id machines[] __initconst =3D {
> +	{ .compatible =3D "raspberrypi,3-model-b-plus" },
> +	{ .compatible =3D "raspberrypi,3-model-b" },
> +	{ .compatible =3D "raspberrypi,2-model-b" },
> +	{ /* sentinel */ }
> +};
> +
> +static int __init raspberrypi_cpufreq_driver_init(void)
> +{
> +	struct platform_device *pdev;
> +	struct device *cpu_dev;
> +	unsigned long min, max;
> +	unsigned long rate;
> +	struct clk *clk;
> +	int ret;
> +
> +	if (!of_match_node(machines, of_root))
> +		return -ENODEV;
> +
> +	cpu_dev =3D get_cpu_device(0);
> +	if (!cpu_dev) {
> +		pr_err("Cannot get CPU for cpufreq driver\n");
> +		return -ENODEV;
> +	}
> +
> +	clk =3D clk_get(cpu_dev, 0);

Please use NULL in this context

Thanks