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Commit d59a68bb authored by Amir Vajid's avatar Amir Vajid Committed by Gerrit - the friendly Code Review server
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soc: qcom: add API for matching voltages across CPUs 



Create an API to match voltages across asymmetric CPUs as
this can be useful in systems with a shared rail across CPUs.
The API takes in one input argument which is the frequency of
a big cluster CPU for which a voltage-equivalent little cluster
CPU frequency is desired. The return value is this little
cluster CPU frequency. All frequencies are in units of kHz.

Change-Id: I821819a0761566984dd7f92014599ff0fcb85e90
Signed-off-by: default avatarAmir Vajid <avajid@codeaurora.org>
parent 863822f1

drivers/soc/qcom/Makefile

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@@ -73,6 +73,7 @@ obj-$(CONFIG_MSM_CORE_CTL_HELPER) += core_ctl_helper.o 
obj-$(CONFIG_MSM_SCM_ERRATA) += scm-errata.o

obj-$(CONFIG_MSM_PFE_WA) += pfe-wa.o

obj-$(CONFIG_MSM_PERFORMANCE) += msm_performance.o

obj-$(CONFIG_ARCH_MSM8996) += msm_cpu_voltage.o



ifdef CONFIG_MSM_SUBSYSTEM_RESTART

	obj-y += subsystem_notif.o

drivers/soc/qcom/msm_cpu_voltage.c

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/*

 * Copyright (c) 2016, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only version 2 as published by the Free Software Foundation.

 *

 * 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/cpu.h>

#include <linux/pm_opp.h>

#include <linux/kernel.h>

#include <soc/qcom/msm_cpu_voltage.h>



#define MAX_FREQ_GAP_KHZ 200000



static unsigned int cls0_max_freq;



static unsigned int get_max_freq(struct device *dev)

{

	struct dev_pm_opp *opp = NULL;

	unsigned long freq = ULONG_MAX;



	if (!dev)

		return 0;



	opp = dev_pm_opp_find_freq_floor(dev, &freq);

	if (IS_ERR(opp))

		return 0;



	freq /= 1000;



	return freq;

}



/**

  * msm_match_cpu_voltage_btol(): match voltage from a big to little cpu

  *

  * @input_freq - big cluster frequency (in kHz)

  *

  * Returns voltage equivalent little cluster frequency (in kHz)

  * or 0 on any error.

  *

  * Function to get a voltage equivalent little cluster frequency

  * for a particular big cluster frequency. Note that input_freq will

  * be rounded up to nearest big cluster frequency. Returned frequency

  * has some restrictions (e.g. can't be more than MAX_FREQ_GAP_KHZ

  * kHz less than input_freq).

  */

unsigned int msm_match_cpu_voltage_btol(unsigned int input_freq)

{

	struct dev_pm_opp *opp = NULL;

	struct device *cls0_dev = NULL;

	struct device *cls1_dev = NULL;

	unsigned long freq = 0;

	unsigned long input_volt = 0;

	unsigned int input_freq_actual = 0;

	unsigned int target_freq = 0;

	unsigned int temp_freq = 0;

	unsigned long temp_volt = 0;

	int i, max_opps_cls0 = 0;



	cls0_dev = get_cpu_device(0);

	if (!cls0_dev) {

		pr_err("Error getting CPU0 device\n");

		return 0;

	}

	cls1_dev = get_cpu_device(2);

	if (!cls1_dev) {

		pr_err("Error getting CPU2 device\n");

		return 0;

	}



	if (cls0_max_freq == 0)

		cls0_max_freq = get_max_freq(cls0_dev);



	/*

	 * Parse Cluster 1 OPP table for closest freq to input_freq

	 * and save its voltage

	 */

	freq = input_freq * 1000;

	rcu_read_lock();

	opp = dev_pm_opp_find_freq_ceil(cls1_dev, &freq);

	if (IS_ERR(opp)) {

		pr_err("Error: could not find freq close to input_freq: %u\n",

				input_freq);

		goto exit;

	}

	input_freq_actual = freq / 1000;

	input_volt = dev_pm_opp_get_voltage(opp);

	if (input_volt == 0) {

		pr_err("Error getting OPP voltage on cluster 1\n");

		goto exit;

	}



	/*

	 * Parse Cluster 0 OPP table for closest voltage to input_volt

	 * and iterate to end to save max freq of Cluster 0

	 */

	max_opps_cls0 = dev_pm_opp_get_opp_count(cls0_dev);

	if (max_opps_cls0 <= 0)

		pr_err("Error getting OPP count for CPU0\n");

	for (i = 0, freq = 0; i < max_opps_cls0; i++, freq++) {

		opp = dev_pm_opp_find_freq_ceil(cls0_dev, &freq);

		if (IS_ERR(opp)) {

			pr_err("Error getting OPP freq on cluster 0\n");

			goto exit;

		}

		temp_freq = freq / 1000;

		temp_volt = dev_pm_opp_get_voltage(opp);

		if (temp_volt >= input_volt) {

			/* Continue to next frequency if gap is too large */

			if ((temp_freq + MAX_FREQ_GAP_KHZ) < input_freq_actual)

				continue;

			/* block freq higher than input_freq */

			if (temp_freq > input_freq)

				target_freq = input_freq;

			else

				target_freq = temp_freq;

			break;

		}

	}



	/*

	 * If we didn't find a frequency, either input voltage is too high

	 * or gap was too large (input frequency was too high). In either

	 * case, return Cluster 0 Fmax as this is the best possible freq.

	 * Also, if input_freq is > Cluster 0 Fmax, return Cluster 0 Fmax.

	 */

	if (target_freq == 0 || input_freq > cls0_max_freq)

		target_freq = cls0_max_freq;

exit:

	rcu_read_unlock();

	return target_freq;

}

EXPORT_SYMBOL(msm_match_cpu_voltage_btol);

include/soc/qcom/msm_cpu_voltage.h

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/*

 * Copyright (c) 2016, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and

 * only version 2 as published by the Free Software Foundation.

 *

 * 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.

 */



unsigned int msm_match_cpu_voltage_btol(unsigned int input_freq);