thermal: Add generic cpu cooling implementation

This patch adds support for generic cpu thermal cooling low level
implementations using frequency scaling and cpuhotplugg currently.
Different cpu related cooling devices can be registered by the
user and the binding of these cooling devices to the corresponding
trip points can be easily done as the registration API's return the
cooling device pointer.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>

1 files changed, 52 insertions, 0 deletions

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+CPU cooling api's How To
+===================================
+
+Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
+
+Updated: 13 Dec 2011
+
+Copyright (c)  2011 Samsung Electronics Co., Ltd(http://www.samsung.com)
+
+0. Introduction
+
+The generic cpu cooling(freq clipping, cpuhotplug) provides
+registration/unregistration api's to the user. The binding of the cooling
+devices to the trip types is left for the user. The registration api's returns
+the cooling device pointer.
+
+1. cpufreq cooling api's
+
+1.1 cpufreq registration api's
+1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
+	struct freq_pctg_table *tab_ptr, unsigned int tab_size,
+	const struct cpumask *mask_val)
+
+    This interface function registers the cpufreq cooling device with the name
+	"thermal-cpufreq".
+
+    tab_ptr: The table containing the percentage of frequency to be clipped for
+    each cooling state.
+	.freq_clip_pctg[NR_CPUS]:Percentage of frequency to be clipped for each
+	 cpu.
+	.polling_interval: polling interval for this cooling state.
+    tab_size: the total number of cooling state.
+    mask_val: all the allowed cpu's where frequency clipping can happen.
+
+1.1.2 void cpufreq_cooling_unregister(void)
+
+    This interface function unregisters the "thermal-cpufreq" cooling device.
+
+
+1.2 cpuhotplug registration api's
+
+1.2.1 struct thermal_cooling_device *cpuhotplug_cooling_register(
+	const struct cpumask *mask_val)
+
+    This interface function registers the cpuhotplug cooling device with the name
+	"thermal-cpuhotplug".
+
+    mask_val: all the allowed cpu's which can be hotplugged out.
+
+1.1.2 void cpuhotplug_cooling_unregister(void)
+
+    This interface function unregisters the "thermal-cpuhotplug" cooling device.