On 20.05.19 12:47, Nicolas Saenz Julienne wrote:
> 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 <nsaenzjulie...@suse.de>
> ---
> drivers/cpufreq/Kconfig.arm | 8 +++
> drivers/cpufreq/Makefile | 1 +
> drivers/cpufreq/raspberrypi-cpufreq.c | 83 +++++++++++++++++++++++++++
> 3 files changed, 92 insertions(+)
> create mode 100644 drivers/cpufreq/raspberrypi-cpufreq.c
>
> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> index 179a1d302f48..f6eba7ae50d0 100644
> --- a/drivers/cpufreq/Kconfig.arm
> +++ b/drivers/cpufreq/Kconfig.arm
> @@ -308,3 +308,11 @@ config ARM_PXA2xx_CPUFREQ
> This add the CPUFreq driver support for Intel PXA2xx SOCs.
>
> If in doubt, say N.
> +
> +config ARM_RASPBERRYPI_CPUFREQ
> + tristate "Raspberry Pi cpufreq support"
> + depends on RASPBERRYPI_FIRMWARE || COMPILE_TEST
The driver doesn't really require the firmware driver to compile, how about:
select RASPBERRYPI_FIRMWARE
> + help
> + This adds the CPUFreq driver for Raspberry Pi
> +
> + If in doubt, say N.
> diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
> index 689b26c6f949..02678e9b2ff5 100644
> --- a/drivers/cpufreq/Makefile
> +++ b/drivers/cpufreq/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_ARM_TEGRA124_CPUFREQ) += tegra124-cpufreq.o
> obj-$(CONFIG_ARM_TEGRA186_CPUFREQ) += tegra186-cpufreq.o
> obj-$(CONFIG_ARM_TI_CPUFREQ) += ti-cpufreq.o
> obj-$(CONFIG_ARM_VEXPRESS_SPC_CPUFREQ) += vexpress-spc-cpufreq.o
> +obj-$(CONFIG_ARM_RASPBERRYPI_CPUFREQ) += raspberrypi-cpufreq.o
>
>
>
> ##################################################################################
> diff --git a/drivers/cpufreq/raspberrypi-cpufreq.c
> b/drivers/cpufreq/raspberrypi-cpufreq.c
> new file mode 100644
> index 000000000000..a85988867d56
> --- /dev/null
> +++ b/drivers/cpufreq/raspberrypi-cpufreq.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Raspberry Pi cpufreq driver
> + *
> + * Copyright (C) 2019, Nicolas Saenz Julienne <nsaenzjulie...@suse.de>
> + */
> +
> +#include <linux/of.h>
> +#include <linux/clk.h>
> +#include <linux/cpu.h>
> +#include <linux/module.h>
> +#include <linux/pm_opp.h>
> +#include <linux/cpufreq.h>
> +#include <linux/platform_device.h>
> +
> +static const struct of_device_id machines[] __initconst = {
> + { .compatible = "raspberrypi,3-model-b-plus" },
> + { .compatible = "raspberrypi,3-model-b" },
> + { /* sentinel */ }
> +};
> +
> +static int __init raspberrypi_cpufreq_driver_init(void)
> +{
> + struct platform_device *pdev;
> + struct device *cpu_dev;
> + struct clk *clk;
> + long min, max;
> + long rate;
> + int ret;
> +
> + if (!of_match_node(machines, of_root))
> + return -ENODEV;
> +
> + cpu_dev = get_cpu_device(0);
> + if (!cpu_dev) {
> + pr_err("Cannot get CPU for cpufreq driver\n");
> + return -ENODEV;
> + }
> +
> + clk = clk_get(cpu_dev, 0);
I suggest use the expected clock ID.
