From: Hans-Christian Egtvedt egtvedt@samfundet.no
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 --- drivers/cpufreq/at32ap-cpufreq.c | 49 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 46 insertions(+), 3 deletions(-)
diff --git a/drivers/cpufreq/at32ap-cpufreq.c b/drivers/cpufreq/at32ap-cpufreq.c index e0c38d9..1d19fa5 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 +87,17 @@ 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 = {