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Commit 848cb944 authored by Hans-Christian Egtvedt's avatar Hans-Christian Egtvedt Committed by Rafael J. Wysocki
Browse files

cpufreq: at32ap: add frequency table 



This patch adds a dynamically calculated frequency table to the at32ap driver.
In short the architecture can scale in power of two between a maximum and
minimum frequency. Min, max, and the steps in between are added to the table.

Signed-off-by: default avatarHans-Christian Egtvedt <egtvedt@samfundet.no>
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 2e6a5c80

drivers/cpufreq/at32ap-cpufreq.c

+46 −3
Original line number Diff line number Diff line
@@ -19,8 +19,10 @@ 
#include <linux/clk.h>

#include <linux/err.h>

#include <linux/export.h>

#include <linux/slab.h>



static struct clk *cpuclk;

static struct cpufreq_frequency_table *freq_table;



static int at32_verify_speed(struct cpufreq_policy *policy)

{
@@ -85,13 +87,17 @@ static int at32_set_target(struct cpufreq_policy *policy, 


static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)

{

	unsigned int frequency, rate;

	int retval, steps, i;



	if (policy->cpu != 0)

		return -EINVAL;



	cpuclk = clk_get(NULL, "cpu");

	if (IS_ERR(cpuclk)) {

		pr_debug("cpufreq: could not get CPU clk\n");

		return PTR_ERR(cpuclk);

		retval = PTR_ERR(cpuclk);

		goto out_err;

	}



	policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
@@ -101,11 +107,48 @@ static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy) 
	policy->min = policy->cpuinfo.min_freq;

	policy->max = policy->cpuinfo.max_freq;



	printk("cpufreq: AT32AP CPU frequency driver\n");

	/*

	 * AVR32 CPU frequency rate scales in power of two between maximum and

	 * minimum, also add space for the table end marker.

	 *

	 * Further validate that the frequency is usable, and append it to the

	 * frequency table.

	 */

	steps = fls(policy->cpuinfo.max_freq / policy->cpuinfo.min_freq) + 1;

	freq_table = kzalloc(steps * sizeof(struct cpufreq_frequency_table),

			GFP_KERNEL);

	if (!freq_table) {

		retval = -ENOMEM;

		goto out_err_put_clk;

	}



	frequency = policy->cpuinfo.max_freq;

	for (i = 0; i < (steps - 1); i++) {

		rate = clk_round_rate(cpuclk, frequency * 1000) / 1000;



		if (rate != frequency)

			freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;

		else

			freq_table[i].frequency = frequency;



		frequency /= 2;

	}



	freq_table[steps - 1].frequency = CPUFREQ_TABLE_END;



	retval = cpufreq_table_validate_and_show(policy, freq_table);

	if (!retval) {

		printk("cpufreq: AT32AP CPU frequency driver\n");

		return 0;

	}



	kfree(freq_table);

out_err_put_clk:

	clk_put(cpuclk);

out_err:

	return retval;

}



static struct cpufreq_driver at32_driver = {

	.name		= "at32ap",

	.init		= at32_cpufreq_driver_init,