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@xxxxxxxxxxxx>
---
drivers/cpufreq/at32ap-cpufreq.c | 47 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/at32ap-cpufreq.c b/drivers/cpufreq/at32ap-cpufreq.c
index 6544887..dbf3f3d 100644
--- a/drivers/cpufreq/at32ap-cpufreq.c
+++ b/drivers/cpufreq/at32ap-cpufreq.c
@@ -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 +87,19 @@ static int at32_set_target(struct cpufreq_policy *policy,
static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)
{
+ unsigned int frequency;
+ int retval;
+ int steps;
+ int 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 +109,46 @@ static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)
policy->min = policy->cpuinfo.min_freq;
policy->max = policy->cpuinfo.max_freq;
+ /*
+ * 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++) {
+ unsigned int rate = clk_round_rate(cpuclk, frequency * 1000);
+ rate /= 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_frequency_table_cpuinfo(policy, freq_table);
+ if (retval)
+ goto out_err_kfree;
+
printk("cpufreq: AT32AP CPU frequency driver\n");
return 0;
+out_err_kfree:
+ kfree(freq_table);
+out_err_put_clk:
+ clk_put(cpuclk);
+out_err:
+ return retval;
}
static struct cpufreq_driver at32_driver = {
--
1.8.1.2
--
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