On Fri, 2019-06-07 at 13:42 +0200, Stefan Wahren wrote: > Hi Nicolas, > > Am 06.06.19 um 16:22 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. > > > > Also, as the firmware interface might be configured as a module, making > > the cpu clock unavailable during init, this implements a full fledged > > driver, as opposed to most drivers registering cpufreq-dt, which only > > make use of an init routine. > > > > Signed-off-by: Nicolas Saenz Julienne <[email protected]> > > Acked-by: Eric Anholt <[email protected]> > > > > --- > > > > Changes since v1: > > - Remove compatible checks > > - Add module support, now full fledged driver > > - Use NULL in clk_get() > > > > drivers/cpufreq/Kconfig.arm | 8 +++ > > drivers/cpufreq/Makefile | 1 + > > drivers/cpufreq/raspberrypi-cpufreq.c | 100 ++++++++++++++++++++++++++ > > 3 files changed, 109 insertions(+) > > create mode 100644 drivers/cpufreq/raspberrypi-cpufreq.c > > > > diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm > > index f8129edc145e..5e9204d443ff 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" > > + depends on CLK_RASPBERRYPI || COMPILE_TEST > > + help > > + This adds the CPUFreq driver for Raspberry Pi > > + > > + 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-$(CONFIG_ARM_PXA2xx_CPUFREQ) += pxa2xx-cpufreq.o > > obj-$(CONFIG_PXA3xx) += pxa3xx-cpufreq.o > > obj-$(CONFIG_ARM_QCOM_CPUFREQ_HW) += qcom-cpufreq-hw.o > > obj-$(CONFIG_ARM_QCOM_CPUFREQ_KRYO) += qcom-cpufreq-kryo.o > > +obj-$(CONFIG_ARM_RASPBERRYPI_CPUFREQ) += raspberrypi-cpufreq.o > > obj-$(CONFIG_ARM_S3C2410_CPUFREQ) += s3c2410-cpufreq.o > > obj-$(CONFIG_ARM_S3C2412_CPUFREQ) += s3c2412-cpufreq.o > > obj-$(CONFIG_ARM_S3C2416_CPUFREQ) += s3c2416-cpufreq.o > > diff --git a/drivers/cpufreq/raspberrypi-cpufreq.c > > b/drivers/cpufreq/raspberrypi-cpufreq.c > > new file mode 100644 > > index 000000000000..99b59d5a50aa > > --- /dev/null > > +++ b/drivers/cpufreq/raspberrypi-cpufreq.c > > @@ -0,0 +1,100 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Raspberry Pi cpufreq driver > > + * > > + * Copyright (C) 2019, Nicolas Saenz Julienne <[email protected]> > > + */ > > + > > +#include <linux/clk.h> > > +#include <linux/cpu.h> > > +#include <linux/cpufreq.h> > > +#include <linux/module.h> > > +#include <linux/platform_device.h> > > +#include <linux/pm_opp.h> > > + > > +static struct platform_device *cpufreq_dt; > > + > > +static int raspberrypi_cpufreq_probe(struct platform_device *pdev) > > +{ > > + struct device *cpu_dev; > > + unsigned long min, max; > > + unsigned long rate; > > + struct clk *clk; > > + int ret; > > + > > + 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, NULL); > > + if (IS_ERR(clk)) { > > + dev_err(cpu_dev, "Cannot get clock for CPU0\n"); > > + return PTR_ERR(clk); > > + } > > + > > + /* > > + * The max and min frequencies are configurable in the Raspberry Pi > > + * firmware, so we query them at runtime > > + */ > > + min = clk_round_rate(clk, 0); > > + max = clk_round_rate(clk, ULONG_MAX); > > + clk_put(clk); > > + > > + for (rate = min; rate < max; rate += 100000000) { > > + ret = dev_pm_opp_add(cpu_dev, rate, 0); > > + if (ret) > > + goto remove_opp; > > + } > > i played a little bit with my Raspberry Pi Zero W and this series. Looks > fine so far. > > Sorry for this nitpicking, but i expect user questions about the > differences between sysfs and vcgencmd measure_clock. > > scaling_available_frequencies gives > > 699999 799999 899999 999999 > > but vcgencmd measure_clock return the rounded up values. > > I know we shouldn't fake anything, but adding the OPPs rounded up may > avoid confusion. > > Stefan
Agree, I'll change this in v3.
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