1 files changed, 485 insertions, 0 deletions
diff --git a/drivers/thermal/clock_cooling.c b/drivers/thermal/clock_cooling.c
new file mode 100644
index 000000000000..1b4ff0f4c716
--- /dev/null
+++ b/drivers/thermal/clock_cooling.c
@@ -0,0 +1,485 @@
+/*
+ *  drivers/thermal/clock_cooling.c
+ *
+ *  Copyright (C) 2014 Eduardo Valentin <edubezval@gmail.com>
+ *
+ *  Copyright (C) 2013	Texas Instruments Inc.
+ *  Contact:  Eduardo Valentin <eduardo.valentin@ti.com>
+ *
+ *  Highly based on cpu_cooling.c.
+ *  Copyright (C) 2012	Samsung Electronics Co., Ltd(http://www.samsung.com)
+ *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ */
+#include <linux/clk.h>
+#include <linux/cpufreq.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/idr.h>
+#include <linux/mutex.h>
+#include <linux/pm_opp.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+#include <linux/clock_cooling.h>
+
+/**
+ * struct clock_cooling_device - data for cooling device with clock
+ * @id: unique integer value corresponding to each clock_cooling_device
+ *	registered.
+ * @dev: struct device pointer to the device being used to cool off using
+ *       clock frequencies.
+ * @cdev: thermal_cooling_device pointer to keep track of the
+ *	registered cooling device.
+ * @clk_rate_change_nb: reference to notifier block used to receive clock
+ *                      rate changes.
+ * @freq_table: frequency table used to keep track of available frequencies.
+ * @clock_state: integer value representing the current state of clock
+ *	cooling	devices.
+ * @clock_val: integer value representing the absolute value of the clipped
+ *	frequency.
+ * @clk: struct clk reference used to enforce clock limits.
+ * @lock: mutex lock to protect this struct.
+ *
+ * This structure is required for keeping information of each
+ * clock_cooling_device registered. In order to prevent corruption of this a
+ * mutex @lock is used.
+ */
+struct clock_cooling_device {
+	int id;
+	struct device *dev;
+	struct thermal_cooling_device *cdev;
+	struct notifier_block clk_rate_change_nb;
+	struct cpufreq_frequency_table *freq_table;
+	unsigned long clock_state;
+	unsigned long clock_val;
+	struct clk *clk;
+	struct mutex lock; /* lock to protect the content of this struct */
+};
+#define to_clock_cooling_device(x) \
+		container_of(x, struct clock_cooling_device, clk_rate_change_nb)
+static DEFINE_IDR(clock_idr);
+static DEFINE_MUTEX(cooling_clock_lock);
+
+/**
+ * clock_cooling_get_idr - function to get an unique id.
+ * @id: int * value generated by this function.
+ *
+ * This function will populate @id with an unique
+ * id, using the idr API.
+ *
+ * Return: 0 on success, an error code on failure.
+ */
+static int clock_cooling_get_idr(int *id)
+{
+	int ret;
+
+	mutex_lock(&cooling_clock_lock);
+	ret = idr_alloc(&clock_idr, NULL, 0, 0, GFP_KERNEL);
+	mutex_unlock(&cooling_clock_lock);
+	if (unlikely(ret < 0))
+		return ret;
+	*id = ret;
+
+	return 0;
+}
+
+/**
+ * release_idr - function to free the unique id.
+ * @id: int value representing the unique id.
+ */
+static void release_idr(int id)
+{
+	mutex_lock(&cooling_clock_lock);
+	idr_remove(&clock_idr, id);
+	mutex_unlock(&cooling_clock_lock);
+}
+
+/* Below code defines functions to be used for clock as cooling device */
+
+enum clock_cooling_property {
+	GET_LEVEL,
+	GET_FREQ,
+	GET_MAXL,
+};
+
+/**
+ * clock_cooling_get_property - fetch a property of interest for a give cpu.
+ * @ccdev: clock cooling device reference
+ * @input: query parameter
+ * @output: query return
+ * @property: type of query (frequency, level, max level)
+ *
+ * This is the common function to
+ * 1. get maximum clock cooling states
+ * 2. translate frequency to cooling state
+ * 3. translate cooling state to frequency
+ * Note that the code may be not in good shape
+ * but it is written in this way in order to:
+ * a) reduce duplicate code as most of the code can be shared.
+ * b) make sure the logic is consistent when translating between
+ *    cooling states and frequencies.
+ *
+ * Return: 0 on success, -EINVAL when invalid parameters are passed.
+ */
+static int clock_cooling_get_property(struct clock_cooling_device *ccdev,
+				      unsigned long input,
+				      unsigned long *output,
+				      enum clock_cooling_property property)
+{
+	int i;
+	unsigned long max_level = 0, level = 0;
+	unsigned int freq = CPUFREQ_ENTRY_INVALID;
+	int descend = -1;
+	struct cpufreq_frequency_table *pos, *table = ccdev->freq_table;
+
+	if (!output)
+		return -EINVAL;
+
+	if (!table)
+		return -EINVAL;
+
+	cpufreq_for_each_valid_entry(pos, table) {
+		/* ignore duplicate entry */
+		if (freq == pos->frequency)
+			continue;
+
+		/* get the frequency order */
+		if (freq != CPUFREQ_ENTRY_INVALID && descend == -1)
+			descend = freq > pos->frequency;
+
+		freq = pos->frequency;
+		max_level++;
+	}
+
+	/* No valid cpu frequency entry */
+	if (max_level == 0)
+		return -EINVAL;
+
+	/* max_level is an index, not a counter */
+	max_level--;
+
+	/* get max level */
+	if (property == GET_MAXL) {
+		*output = max_level;
+		return 0;
+	}
+
+	if (property == GET_FREQ)
+		level = descend ? input : (max_level - input);
+
+	i = 0;
+	cpufreq_for_each_valid_entry(pos, table) {
+		/* ignore duplicate entry */
+		if (freq == pos->frequency)
+			continue;
+
+		/* now we have a valid frequency entry */
+		freq = pos->frequency;
+
+		if (property == GET_LEVEL && (unsigned int)input == freq) {
+			/* get level by frequency */
+			*output = descend ? i : (max_level - i);
+			return 0;
+		}
+		if (property == GET_FREQ && level == i) {
+			/* get frequency by level */
+			*output = freq;
+			return 0;
+		}
+		i++;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * clock_cooling_get_level - return the cooling level of given clock cooling.
+ * @cdev: reference of a thermal cooling device of used as clock cooling device
+ * @freq: the frequency of interest
+ *
+ * This function will match the cooling level corresponding to the
+ * requested @freq and return it.
+ *
+ * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
+ * otherwise.
+ */
+unsigned long clock_cooling_get_level(struct thermal_cooling_device *cdev,
+				      unsigned long freq)
+{
+	struct clock_cooling_device *ccdev = cdev->devdata;
+	unsigned long val;
+
+	if (clock_cooling_get_property(ccdev, (unsigned long)freq, &val,
+				       GET_LEVEL))
+		return THERMAL_CSTATE_INVALID;
+
+	return val;
+}
+EXPORT_SYMBOL_GPL(clock_cooling_get_level);
+
+/**
+ * clock_cooling_get_frequency - get the absolute value of frequency from level.
+ * @ccdev: clock cooling device reference
+ * @level: cooling level
+ *
+ * This function matches cooling level with frequency. Based on a cooling level
+ * of frequency, equals cooling state of cpu cooling device, it will return
+ * the corresponding frequency.
+ *	e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
+ *
+ * Return: 0 on error, the corresponding frequency otherwise.
+ */
+static unsigned long
+clock_cooling_get_frequency(struct clock_cooling_device *ccdev,
+			    unsigned long level)
+{
+	int ret = 0;
+	unsigned long freq;
+
+	ret = clock_cooling_get_property(ccdev, level, &freq, GET_FREQ);
+	if (ret)
+		return 0;
+
+	return freq;
+}
+
+/**
+ * clock_cooling_apply - function to apply frequency clipping.
+ * @ccdev: clock_cooling_device pointer containing frequency clipping data.
+ * @cooling_state: value of the cooling state.
+ *
+ * Function used to make sure the clock layer is aware of current thermal
+ * limits. The limits are applied by updating the clock rate in case it is
+ * higher than the corresponding frequency based on the requested cooling_state.
+ *
+ * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
+ * cooling state).
+ */
+static int clock_cooling_apply(struct clock_cooling_device *ccdev,
+			       unsigned long cooling_state)
+{
+	unsigned long clip_freq, cur_freq;
+	int ret = 0;
+
+	/* Here we write the clipping */
+	/* Check if the old cooling action is same as new cooling action */
+	if (ccdev->clock_state == cooling_state)
+		return 0;
+
+	clip_freq = clock_cooling_get_frequency(ccdev, cooling_state);
+	if (!clip_freq)
+		return -EINVAL;
+
+	cur_freq = clk_get_rate(ccdev->clk);
+
+	mutex_lock(&ccdev->lock);
+	ccdev->clock_state = cooling_state;
+	ccdev->clock_val = clip_freq;
+	/* enforce clock level */
+	if (cur_freq > clip_freq)
+		ret = clk_set_rate(ccdev->clk, clip_freq);
+	mutex_unlock(&ccdev->lock);
+
+	return ret;
+}
+
+/**
+ * clock_cooling_clock_notifier - notifier callback on clock rate changes.
+ * @nb:	struct notifier_block * with callback info.
+ * @event: value showing clock event for which this function invoked.
+ * @data: callback-specific data
+ *
+ * Callback to hijack the notification on clock transition.
+ * Every time there is a clock change, we intercept all pre change events
+ * and block the transition in case the new rate infringes thermal limits.
+ *
+ * Return: NOTIFY_DONE (success) or NOTIFY_BAD (new_rate > thermal limit).
+ */
+static int clock_cooling_clock_notifier(struct notifier_block *nb,
+					unsigned long event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct clock_cooling_device *ccdev = to_clock_cooling_device(nb);
+
+	switch (event) {
+	case PRE_RATE_CHANGE:
+		/*
+		 * checks on current state
+		 * TODO: current method is not best we can find as it
+		 * allows possibly voltage transitions, in case DVFS
+		 * layer is also hijacking clock pre notifications.
+		 */
+		if (ndata->new_rate > ccdev->clock_val)
+			return NOTIFY_BAD;
+		/* fall through */
+	case POST_RATE_CHANGE:
+	case ABORT_RATE_CHANGE:
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+/* clock cooling device thermal callback functions are defined below */
+
+/**
+ * clock_cooling_get_max_state - callback function to get the max cooling state.
+ * @cdev: thermal cooling device pointer.
+ * @state: fill this variable with the max cooling state.
+ *
+ * Callback for the thermal cooling device to return the clock
+ * max cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int clock_cooling_get_max_state(struct thermal_cooling_device *cdev,
+				       unsigned long *state)
+{
+	struct clock_cooling_device *ccdev = cdev->devdata;
+	unsigned long count = 0;
+	int ret;
+
+	ret = clock_cooling_get_property(ccdev, 0, &count, GET_MAXL);
+	if (!ret)
+		*state = count;
+
+	return ret;
+}
+
+/**
+ * clock_cooling_get_cur_state - function to get the current cooling state.
+ * @cdev: thermal cooling device pointer.
+ * @state: fill this variable with the current cooling state.
+ *
+ * Callback for the thermal cooling device to return the clock
+ * current cooling state.
+ *
+ * Return: 0 (success)
+ */
+static int clock_cooling_get_cur_state(struct thermal_cooling_device *cdev,
+				       unsigned long *state)
+{
+	struct clock_cooling_device *ccdev = cdev->devdata;
+
+	*state = ccdev->clock_state;
+
+	return 0;
+}
+
+/**
+ * clock_cooling_set_cur_state - function to set the current cooling state.
+ * @cdev: thermal cooling device pointer.
+ * @state: set this variable to the current cooling state.
+ *
+ * Callback for the thermal cooling device to change the clock cooling
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
+ */
+static int clock_cooling_set_cur_state(struct thermal_cooling_device *cdev,
+				       unsigned long state)
+{
+	struct clock_cooling_device *clock_device = cdev->devdata;
+
+	return clock_cooling_apply(clock_device, state);
+}
+
+/* Bind clock callbacks to thermal cooling device ops */
+static struct thermal_cooling_device_ops const clock_cooling_ops = {
+	.get_max_state = clock_cooling_get_max_state,
+	.get_cur_state = clock_cooling_get_cur_state,
+	.set_cur_state = clock_cooling_set_cur_state,
+};
+
+/**
+ * clock_cooling_register - function to create clock cooling device.
+ * @dev: struct device pointer to the device used as clock cooling device.
+ * @clock_name: string containing the clock used as cooling mechanism.
+ *
+ * This interface function registers the clock cooling device with the name
+ * "thermal-clock-%x". The cooling device is based on clock frequencies.
+ * The struct device is assumed to be capable of DVFS transitions.
+ * The OPP layer is used to fetch and fill the available frequencies for
+ * the referred device. The ordered frequency table is used to control
+ * the clock cooling device cooling states and to limit clock transitions
+ * based on the cooling state requested by the thermal framework.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+clock_cooling_register(struct device *dev, const char *clock_name)
+{
+	struct thermal_cooling_device *cdev;
+	struct clock_cooling_device *ccdev = NULL;
+	char dev_name[THERMAL_NAME_LENGTH];
+	int ret = 0;
+
+	ccdev = devm_kzalloc(dev, sizeof(*ccdev), GFP_KERNEL);
+	if (!ccdev)
+		return ERR_PTR(-ENOMEM);
+
+	ccdev->dev = dev;
+	ccdev->clk = devm_clk_get(dev, clock_name);
+	if (IS_ERR(ccdev->clk))
+		return ERR_CAST(ccdev->clk);
+
+	ret = clock_cooling_get_idr(&ccdev->id);
+	if (ret)
+		return ERR_PTR(-EINVAL);
+
+	snprintf(dev_name, sizeof(dev_name), "thermal-clock-%d", ccdev->id);
+
+	cdev = thermal_cooling_device_register(dev_name, ccdev,
+					       &clock_cooling_ops);
+	if (IS_ERR(cdev)) {
+		release_idr(ccdev->id);
+		return ERR_PTR(-EINVAL);
+	}
+	ccdev->cdev = cdev;
+	ccdev->clk_rate_change_nb.notifier_call = clock_cooling_clock_notifier;
+
+	/* Assuming someone has already filled the opp table for this device */
+	ret = dev_pm_opp_init_cpufreq_table(dev, &ccdev->freq_table);
+	if (ret) {
+		release_idr(ccdev->id);
+		return ERR_PTR(ret);
+	}
+	ccdev->clock_state = 0;
+	ccdev->clock_val = clock_cooling_get_frequency(ccdev, 0);
+
+	clk_notifier_register(ccdev->clk, &ccdev->clk_rate_change_nb);
+
+	return cdev;
+}
+EXPORT_SYMBOL_GPL(clock_cooling_register);
+
+/**
+ * clock_cooling_unregister - function to remove clock cooling device.
+ * @cdev: thermal cooling device pointer.
+ *
+ * This interface function unregisters the "thermal-clock-%x" cooling device.
+ */
+void clock_cooling_unregister(struct thermal_cooling_device *cdev)
+{
+	struct clock_cooling_device *ccdev;
+
+	if (!cdev)
+		return;
+
+	ccdev = cdev->devdata;
+
+	clk_notifier_unregister(ccdev->clk, &ccdev->clk_rate_change_nb);
+	dev_pm_opp_free_cpufreq_table(ccdev->dev, &ccdev->freq_table);
+
+	thermal_cooling_device_unregister(ccdev->cdev);
+	release_idr(ccdev->id);
+}
+EXPORT_SYMBOL_GPL(clock_cooling_unregister);