linux-kernel - [PATCH 0/4] cpufreq support for the Raspberry Pi

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Date:   Tue,  4 Jun 2019 19:32:18 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     stefan.wahren@...e.com, linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org
Cc:     mbrugger@...e.de, viresh.kumar@...aro.org, rjw@...ysocki.net,
        sboyd@...nel.org, eric@...olt.net, f.fainelli@...il.com,
        bcm-kernel-feedback-list@...adcom.com, ptesarik@...e.com,
        ssuloev@...altech.com, linux-clk@...r.kernel.org,
        mturquette@...libre.com,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 0/4] cpufreq support for the Raspberry Pi

Hi all,
this series aims at adding cpufreq support to the Raspberry Pi family of
boards.

The previous revision can be found at: https://lkml.org/lkml/2019/5/20/431

The series first factors out 'pllb' from clk-bcm2385 and creates a new
clk driver that operates it over RPi's firmware interface[1]. We are
forced to do so as the firmware 'owns' the pll and we're not allowed to
change through the register interface directly as we might race with the
over-temperature and under-voltage protections provided by the firmware.

Next it creates a minimal cpufreq driver that populates the CPU's opp
table, and registers cpufreq-dt. Which is needed as the firmware
controls the max and min frequencies available.

This was tested on a RPi3b+ and RPI2b which are the boards I have access
to. Until this is tested broadly the cpufreq driver takes care of
filtering out the rest of boards.

That's all,
kind regards,
Nicolas

[1] https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface

---

Changes since RFC:
  - Addressed Viresh's comments in cpufreq driver
  - Addressed Stefan's comments in both cpufreq & clk drivers
  - Moved all firmware clk operations into it's own driver

Nicolas Saenz Julienne (4):
  clk: bcm2835: remove pllb
  clk: bcm283x: add driver interfacing with Raspberry Pi's firmware
  clk: bcm2835: register Raspberry Pi's firmware clk device
  cpufreq: add driver for Raspbery Pi

 drivers/clk/bcm/Makefile              |   1 +
 drivers/clk/bcm/clk-bcm2835.c         |  40 ++--
 drivers/clk/bcm/clk-raspberrypi.c     | 316 ++++++++++++++++++++++++++
 drivers/cpufreq/Kconfig.arm           |   8 +
 drivers/cpufreq/Makefile              |   1 +
 drivers/cpufreq/raspberrypi-cpufreq.c |  84 +++++++
 6 files changed, 423 insertions(+), 27 deletions(-)
 create mode 100644 drivers/clk/bcm/clk-raspberrypi.c
 create mode 100644 drivers/cpufreq/raspberrypi-cpufreq.c

-- 
2.21.0