[PATCH v3 0/6] thermal: exynos: Add kernel thermal support for exynos platform

Amit Daniel Kachhap amit.kachhap at linaro.org
Tue May 8 12:18:12 EDT 2012

Hi Andrew,

This patchset introduces a new generic cooling device based on cpufreq that
can be used on non-ACPI platforms. As a proof of concept, we have drivers for
the following platforms using this mechanism now:

 * TI OMAP (git://git.linaro.org/people/amitdanielk/linux.git omap4460_thermal)
 * Samsung Exynos (Exynos4 and Exynos5) in the current patchset.
 * Freescale i.MX (git://git.linaro.org/people/amitdanielk/linux.git imx6q_thermal)

These patches have been reviewed by Rui Zhang (https://lkml.org/lkml/2012/4/9/448)
who seems to agree with them in principle, but I haven't had any luck getting them
merged, perhaps a lack of maintainer bandwidth.

ACPI platforms currently have such a mechanism but it is wrapped in ACPI'isms
that we don't have on ARM platforms. If this is accepted, I'm proposing to
convert over the ACPI thermal driver to use this common code too.

Can you please merge these patches for 3.5?

Amit Daniel

Changes since V2:
*Added Exynos5 TMU sensor support by enhancing the exynos4 tmu driver. Exynos5 TMU
 driver was internally developed by SangWook Ju <sw.ju at samsung.com>.
*Removed cpuhotplug cooling code in this patchset.
*Rebased the patches against 3.4-rc6 kernel.

Changes since V1:
*Moved the sensor driver to driver/thermal folder from driver/hwmon folder
 as suggested by Mark Brown and Guenter Roeck 
*Added notifier support to notify the registered drivers of any cpu cooling
 action. The driver can modify the default cooling behaviour(eg set different
 max clip frequency).
*The percentage based frequency replaced with absolute clipped frequency.
*Some more conditional checks when setting max frequency.
*Renamed the new trip type THERMAL_TRIP_STATE_ACTIVE to
*Many review comments from R, Durgadoss <durgadoss.r at intel.com> and 
 eduardo.valentin at ti.com implemented.
*Removed cooling stats through debugfs patch
*The V1 based can be found here,

Changes since RFC:
*Changed the cpu cooling registration/unregistration API's to instance based
*Changed the STATE_ACTIVE trip type to pass correct instance id
*Adding support to restore back the policy->max_freq after doing frequency 
*Moved the trip cooling stats from sysfs node to debugfs node as suggested
  by Greg KH greg at kroah.com 
*Incorporated several review comments from eduardo.valentin at ti.com
*Moved the Temperature sensor driver from driver/hwmon/ to driver/mfd
 as discussed with Guenter Roeck <guenter.roeck at ericsson.com> and 
 Donggeun Kim <dg77.kim at samsung.com> (https://lkml.org/lkml/2012/1/5/7)
*Some changes according to the changes in common cpu cooling APIs
*The RFC based patches can be found here,

Brief Description:

1) The generic cooling devices code is placed inside driver/thermal/* as 
placing inside acpi folder will need un-necessary enabling of acpi code. This
codes is architecture independent.

2) This patchset adds a new trip type THERMAL_TRIP_STATE_INSTANCE which passes
cooling device instance number and may be helpful for cpufreq cooling devices
to take the correct cooling action. This trip type avoids the temperature
comparision check again inside the cooling handler.

3) This patchset adds generic cpu cooling low level implementation through
frequency clipping and cpu hotplug. In future, other cpu related cooling
devices may be added here. An ACPI version of this already exists
(drivers/acpi/processor_thermal.c). But this will be useful for platforms
like ARM using the generic thermal interface along with the generic cpu
cooling devices. The cooling device registration API's return cooling device
pointers which can be easily binded with the thermal zone trip points.
The important APIs exposed are,
   a)struct thermal_cooling_device *cpufreq_cooling_register(
	struct freq_clip_table *tab_ptr, unsigned int tab_size,
	const struct cpumask *mask_val)
   b)void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)

4) Samsung exynos platform thermal implementation is done using the generic
cpu cooling APIs and the new trip type. The temperature sensor driver present
in the hwmon folder(registered as hwmon driver) is moved to thermal folder
and registered as a thermal driver.

All this patchset is based on Kernel version 3.4-rc6 

A simple data/control flow diagrams is shown below,

Core Linux thermal <----->  Exynos thermal interface <----- Temperature Sensor
	  |                             |
	 \|/                            |
  Cpufreq cooling device <---------------

*Will send the DT enablement patches later after the driver is merged.

Amit Daniel Kachhap (6):
  thermal: Add a new trip type to use cooling device instance number
  thermal: Add generic cpufreq cooling implementation
  hwmon: exynos4: Move thermal sensor driver to driver/thermal
  thermal: exynos5: Add exynos5 thermal sensor driver support
  thermal: exynos: Register the tmu sensor with the kernel thermal
  ARM: exynos: Add thermal sensor driver platform data support

 Documentation/hwmon/exynos4_tmu              |   81 ---
 Documentation/thermal/cpu-cooling-api.txt    |   60 ++
 Documentation/thermal/exynos_thermal         |   52 ++
 Documentation/thermal/sysfs-api.txt          |    4 +-
 drivers/hwmon/Kconfig                        |   10 -
 drivers/hwmon/Makefile                       |    1 -
 drivers/hwmon/exynos4_tmu.c                  |  514 --------------
 drivers/thermal/Kconfig                      |   20 +
 drivers/thermal/Makefile                     |    4 +-
 drivers/thermal/cpu_cooling.c                |  359 ++++++++++
 drivers/thermal/exynos_thermal.c             |  933 ++++++++++++++++++++++++++
 drivers/thermal/thermal_sys.c                |   62 ++-
 include/linux/cpu_cooling.h                  |   62 ++
 include/linux/platform_data/exynos4_tmu.h    |   83 ---
 include/linux/platform_data/exynos_thermal.h |  100 +++
 include/linux/thermal.h                      |    1 +
 16 files changed, 1651 insertions(+), 695 deletions(-)
 delete mode 100644 Documentation/hwmon/exynos4_tmu
 create mode 100644 Documentation/thermal/cpu-cooling-api.txt
 create mode 100644 Documentation/thermal/exynos_thermal
 delete mode 100644 drivers/hwmon/exynos4_tmu.c
 create mode 100644 drivers/thermal/cpu_cooling.c
 create mode 100644 drivers/thermal/exynos_thermal.c
 create mode 100644 include/linux/cpu_cooling.h
 delete mode 100644 include/linux/platform_data/exynos4_tmu.h
 create mode 100644 include/linux/platform_data/exynos_thermal.h

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