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162 lines
4.8 KiB
Diff
162 lines
4.8 KiB
Diff
From 1c0d3626312369837bc18051ed6c9611323fce87 Mon Sep 17 00:00:00 2001
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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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Date: Wed, 12 Jun 2019 20:24:56 +0200
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Subject: [PATCH] cpufreq: add driver for Raspberry Pi
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Commit d3df18a97e586702920337056540267807b23f8e upstream.
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Raspberry Pi's firmware offers and interface though which update it's
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performance requirements. It allows us to request for specific runtime
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frequencies, which the firmware might or might not respect, depending on
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the firmware configuration and thermals.
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As the maximum and minimum frequencies are configurable in the firmware
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there is no way to know in advance their values. So the Raspberry Pi
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cpufreq driver queries them, builds an opp frequency table to then
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launch cpufreq-dt.
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Also, as the firmware interface might be configured as a module, making
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the cpu clock unavailable during init, this implements a full fledged
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driver, as opposed to most drivers registering cpufreq-dt, which only
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make use of an init routine.
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Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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Acked-by: Eric Anholt <eric@anholt.net>
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Reviewed-by: Stephen Boyd <sboyd@kernel.org>
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Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
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Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
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---
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drivers/cpufreq/Kconfig.arm | 8 +++
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drivers/cpufreq/Makefile | 1 +
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drivers/cpufreq/raspberrypi-cpufreq.c | 97 +++++++++++++++++++++++++++
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3 files changed, 106 insertions(+)
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create mode 100644 drivers/cpufreq/raspberrypi-cpufreq.c
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--- a/drivers/cpufreq/Kconfig.arm
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+++ b/drivers/cpufreq/Kconfig.arm
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@@ -121,6 +121,14 @@ config ARM_QCOM_CPUFREQ_KRYO
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If in doubt, say N.
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+config ARM_RASPBERRYPI_CPUFREQ
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+ tristate "Raspberry Pi cpufreq support"
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+ depends on CLK_RASPBERRYPI || COMPILE_TEST
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+ help
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+ This adds the CPUFreq driver for Raspberry Pi
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+
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+ If in doubt, say N.
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+
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config ARM_S3C_CPUFREQ
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bool
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help
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--- a/drivers/cpufreq/Makefile
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+++ b/drivers/cpufreq/Makefile
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@@ -65,6 +65,7 @@ obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ) += o
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obj-$(CONFIG_ARM_PXA2xx_CPUFREQ) += pxa2xx-cpufreq.o
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obj-$(CONFIG_PXA3xx) += pxa3xx-cpufreq.o
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obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO) += qcom-cpufreq-kryo.o
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+obj-$(CONFIG_ARM_RASPBERRYPI_CPUFREQ) += raspberrypi-cpufreq.o
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obj-$(CONFIG_ARM_S3C2410_CPUFREQ) += s3c2410-cpufreq.o
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obj-$(CONFIG_ARM_S3C2412_CPUFREQ) += s3c2412-cpufreq.o
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obj-$(CONFIG_ARM_S3C2416_CPUFREQ) += s3c2416-cpufreq.o
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--- /dev/null
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+++ b/drivers/cpufreq/raspberrypi-cpufreq.c
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@@ -0,0 +1,97 @@
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+// SPDX-License-Identifier: GPL-2.0
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+/*
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+ * Raspberry Pi cpufreq driver
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+ *
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+ * Copyright (C) 2019, Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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+ */
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+
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+#include <linux/clk.h>
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+#include <linux/cpu.h>
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+#include <linux/cpufreq.h>
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+#include <linux/module.h>
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+#include <linux/platform_device.h>
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+#include <linux/pm_opp.h>
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+
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+#define RASPBERRYPI_FREQ_INTERVAL 100000000
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+
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+static struct platform_device *cpufreq_dt;
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+
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+static int raspberrypi_cpufreq_probe(struct platform_device *pdev)
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+{
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+ struct device *cpu_dev;
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+ unsigned long min, max;
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+ unsigned long rate;
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+ struct clk *clk;
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+ int ret;
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+
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+ cpu_dev = get_cpu_device(0);
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+ if (!cpu_dev) {
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+ pr_err("Cannot get CPU for cpufreq driver\n");
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+ return -ENODEV;
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+ }
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+
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+ clk = clk_get(cpu_dev, NULL);
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+ if (IS_ERR(clk)) {
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+ dev_err(cpu_dev, "Cannot get clock for CPU0\n");
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+ return PTR_ERR(clk);
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+ }
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+
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+ /*
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+ * The max and min frequencies are configurable in the Raspberry Pi
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+ * firmware, so we query them at runtime.
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+ */
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+ min = roundup(clk_round_rate(clk, 0), RASPBERRYPI_FREQ_INTERVAL);
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+ max = roundup(clk_round_rate(clk, ULONG_MAX), RASPBERRYPI_FREQ_INTERVAL);
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+ clk_put(clk);
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+
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+ for (rate = min; rate <= max; rate += RASPBERRYPI_FREQ_INTERVAL) {
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+ ret = dev_pm_opp_add(cpu_dev, rate, 0);
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+ if (ret)
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+ goto remove_opp;
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+ }
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+
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+ cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
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+ ret = PTR_ERR_OR_ZERO(cpufreq_dt);
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+ if (ret) {
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+ dev_err(cpu_dev, "Failed to create platform device, %d\n", ret);
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+ goto remove_opp;
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+ }
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+
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+ return 0;
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+
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+remove_opp:
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+ dev_pm_opp_remove_all_dynamic(cpu_dev);
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+
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+ return ret;
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+}
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+
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+static int raspberrypi_cpufreq_remove(struct platform_device *pdev)
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+{
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+ struct device *cpu_dev;
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+
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+ cpu_dev = get_cpu_device(0);
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+ if (cpu_dev)
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+ dev_pm_opp_remove_all_dynamic(cpu_dev);
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+
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+ platform_device_unregister(cpufreq_dt);
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+
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+ return 0;
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+}
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+
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+/*
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+ * Since the driver depends on clk-raspberrypi, which may return EPROBE_DEFER,
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+ * all the activity is performed in the probe, which may be defered as well.
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+ */
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+static struct platform_driver raspberrypi_cpufreq_driver = {
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+ .driver = {
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+ .name = "raspberrypi-cpufreq",
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+ },
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+ .probe = raspberrypi_cpufreq_probe,
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+ .remove = raspberrypi_cpufreq_remove,
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+};
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+module_platform_driver(raspberrypi_cpufreq_driver);
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+
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+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de");
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+MODULE_DESCRIPTION("Raspberry Pi cpufreq driver");
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+MODULE_LICENSE("GPL");
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+MODULE_ALIAS("platform:raspberrypi-cpufreq");
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