target/linux/brcm2708/patches-4.19/950-0761-cpufreq-add-driver-for-Raspberry-Pi.patch

   1 From 1c0d3626312369837bc18051ed6c9611323fce87 Mon Sep 17 00:00:00 2001
   2 From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
   3 Date: Wed, 12 Jun 2019 20:24:56 +0200
   4 Subject: [PATCH] cpufreq: add driver for Raspberry Pi
   5
   6 Commit d3df18a97e586702920337056540267807b23f8e upstream.
   7
   8 Raspberry Pi's firmware offers and interface though which update it's
   9 performance requirements. It allows us to request for specific runtime
  10 frequencies, which the firmware might or might not respect, depending on
  11 the firmware configuration and thermals.
  12
  13 As the maximum and minimum frequencies are configurable in the firmware
  14 there is no way to know in advance their values. So the Raspberry Pi
  15 cpufreq driver queries them, builds an opp frequency table to then
  16 launch cpufreq-dt.
  17
  18 Also, as the firmware interface might be configured as a module, making
  19 the cpu clock unavailable during init, this implements a full fledged
  20 driver, as opposed to most drivers registering cpufreq-dt, which only
  21 make use of an init routine.
  22
  23 Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  24 Acked-by: Eric Anholt <eric@anholt.net>
  25 Reviewed-by: Stephen Boyd <sboyd@kernel.org>
  26 Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
  27 Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
  28 ---
  29  drivers/cpufreq/Kconfig.arm           |  8 +++
  30  drivers/cpufreq/Makefile              |  1 +
  31  drivers/cpufreq/raspberrypi-cpufreq.c | 97 +++++++++++++++++++++++++++
  32  3 files changed, 106 insertions(+)
  33  create mode 100644 drivers/cpufreq/raspberrypi-cpufreq.c
  34
  35 --- a/drivers/cpufreq/Kconfig.arm
  36 +++ b/drivers/cpufreq/Kconfig.arm
  37 @@ -121,6 +121,14 @@ config ARM_QCOM_CPUFREQ_KRYO
  38
  39           If in doubt, say N.
  40
  41 +config ARM_RASPBERRYPI_CPUFREQ
  42 +       tristate "Raspberry Pi cpufreq support"
  43 +       depends on CLK_RASPBERRYPI || COMPILE_TEST
  44 +       help
  45 +         This adds the CPUFreq driver for Raspberry Pi
  46 +
  47 +         If in doubt, say N.
  48 +
  49  config ARM_S3C_CPUFREQ
  50         bool
  51         help
  52 --- a/drivers/cpufreq/Makefile
  53 +++ b/drivers/cpufreq/Makefile
  54 @@ -65,6 +65,7 @@ obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ)   += o
  55  obj-$(CONFIG_ARM_PXA2xx_CPUFREQ)       += pxa2xx-cpufreq.o
  56  obj-$(CONFIG_PXA3xx)                   += pxa3xx-cpufreq.o
  57  obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO)    += qcom-cpufreq-kryo.o
  58 +obj-$(CONFIG_ARM_RASPBERRYPI_CPUFREQ)  += raspberrypi-cpufreq.o
  59  obj-$(CONFIG_ARM_S3C2410_CPUFREQ)      += s3c2410-cpufreq.o
  60  obj-$(CONFIG_ARM_S3C2412_CPUFREQ)      += s3c2412-cpufreq.o
  61  obj-$(CONFIG_ARM_S3C2416_CPUFREQ)      += s3c2416-cpufreq.o
  62 --- /dev/null
  63 +++ b/drivers/cpufreq/raspberrypi-cpufreq.c
  64 @@ -0,0 +1,97 @@
  65 +// SPDX-License-Identifier: GPL-2.0
  66 +/*
  67 + * Raspberry Pi cpufreq driver
  68 + *
  69 + * Copyright (C) 2019, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  70 + */
  71 +
  72 +#include <linux/clk.h>
  73 +#include <linux/cpu.h>
  74 +#include <linux/cpufreq.h>
  75 +#include <linux/module.h>
  76 +#include <linux/platform_device.h>
  77 +#include <linux/pm_opp.h>
  78 +
  79 +#define RASPBERRYPI_FREQ_INTERVAL      100000000
  80 +
  81 +static struct platform_device *cpufreq_dt;
  82 +
  83 +static int raspberrypi_cpufreq_probe(struct platform_device *pdev)
  84 +{
  85 +       struct device *cpu_dev;
  86 +       unsigned long min, max;
  87 +       unsigned long rate;
  88 +       struct clk *clk;
  89 +       int ret;
  90 +
  91 +       cpu_dev = get_cpu_device(0);
  92 +       if (!cpu_dev) {
  93 +               pr_err("Cannot get CPU for cpufreq driver\n");
  94 +               return -ENODEV;
  95 +       }
  96 +
  97 +       clk = clk_get(cpu_dev, NULL);
  98 +       if (IS_ERR(clk)) {
  99 +               dev_err(cpu_dev, "Cannot get clock for CPU0\n");
 100 +               return PTR_ERR(clk);
 101 +       }
 102 +
 103 +       /*
 104 +        * The max and min frequencies are configurable in the Raspberry Pi
 105 +        * firmware, so we query them at runtime.
 106 +        */
 107 +       min = roundup(clk_round_rate(clk, 0), RASPBERRYPI_FREQ_INTERVAL);
 108 +       max = roundup(clk_round_rate(clk, ULONG_MAX), RASPBERRYPI_FREQ_INTERVAL);
 109 +       clk_put(clk);
 110 +
 111 +       for (rate = min; rate <= max; rate += RASPBERRYPI_FREQ_INTERVAL) {
 112 +               ret = dev_pm_opp_add(cpu_dev, rate, 0);
 113 +               if (ret)
 114 +                       goto remove_opp;
 115 +       }
 116 +
 117 +       cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
 118 +       ret = PTR_ERR_OR_ZERO(cpufreq_dt);
 119 +       if (ret) {
 120 +               dev_err(cpu_dev, "Failed to create platform device, %d\n", ret);
 121 +               goto remove_opp;
 122 +       }
 123 +
 124 +       return 0;
 125 +
 126 +remove_opp:
 127 +       dev_pm_opp_remove_all_dynamic(cpu_dev);
 128 +
 129 +       return ret;
 130 +}
 131 +
 132 +static int raspberrypi_cpufreq_remove(struct platform_device *pdev)
 133 +{
 134 +       struct device *cpu_dev;
 135 +
 136 +       cpu_dev = get_cpu_device(0);
 137 +       if (cpu_dev)
 138 +               dev_pm_opp_remove_all_dynamic(cpu_dev);
 139 +
 140 +       platform_device_unregister(cpufreq_dt);
 141 +
 142 +       return 0;
 143 +}
 144 +
 145 +/*
 146 + * Since the driver depends on clk-raspberrypi, which may return EPROBE_DEFER,
 147 + * all the activity is performed in the probe, which may be defered as well.
 148 + */
 149 +static struct platform_driver raspberrypi_cpufreq_driver = {
 150 +       .driver = {
 151 +               .name = "raspberrypi-cpufreq",
 152 +       },
 153 +       .probe          = raspberrypi_cpufreq_probe,
 154 +       .remove         = raspberrypi_cpufreq_remove,
 155 +};
 156 +module_platform_driver(raspberrypi_cpufreq_driver);
 157 +
 158 +MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de");
 159 +MODULE_DESCRIPTION("Raspberry Pi cpufreq driver");
 160 +MODULE_LICENSE("GPL");
 161 +MODULE_ALIAS("platform:raspberrypi-cpufreq");