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cpufreq: at32ap: add frequency table

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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: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hans-Christian Egtvedt 2013-09-16 18:56:41 +05:30 committed by Rafael J. Wysocki
parent 2e6a5c80e6
commit 848cb94421
1 changed files with 46 additions and 3 deletions
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49
drivers/cpufreq/at32ap-cpufreq.c
View file

@ -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;
@ -101,9 +107,46 @@ 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;
}
return 0;
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 = {