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cpufreq / CPPC: Add cpuinfo_cur_freq support for CPPC

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Per Section 8.4.7.1.3 of ACPI 6.2, the platform provides performance
feedback via set of performance counters. To determine the actual
performance level delivered over time, OSPM may read a set of
performance counters from the Reference Performance Counter Register
and the Delivered Performance Counter Register.

OSPM calculates the delivered performance over a given time period by
taking a beginning and ending snapshot of both the reference and
delivered performance counters, and calculating:

delivered_perf = reference_perf X (delta of delivered_perf counter / delta of reference_perf counter).

Implement the above and hook this up to the cpufreq->get method.

Signed-off-by: George Cherian <george.cherian@cavium.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
George Cherian 2018-07-11 23:07:55 -07:00 committed by Rafael J. Wysocki
parent 1c3528232f
commit 33477d84c2
1 changed files with 52 additions and 0 deletions
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52
drivers/cpufreq/cppc_cpufreq.c
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@ -296,10 +296,62 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
return ret;
}
static inline u64 get_delta(u64 t1, u64 t0)
{
if (t1 > t0 || t0 > ~(u32)0)
return t1 - t0;
return (u32)t1 - (u32)t0;
}
static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu,
struct cppc_perf_fb_ctrs fb_ctrs_t0,
struct cppc_perf_fb_ctrs fb_ctrs_t1)
{
u64 delta_reference, delta_delivered;
u64 reference_perf, delivered_perf;
reference_perf = fb_ctrs_t0.reference_perf;
delta_reference = get_delta(fb_ctrs_t1.reference,
fb_ctrs_t0.reference);
delta_delivered = get_delta(fb_ctrs_t1.delivered,
fb_ctrs_t0.delivered);
/* Check to avoid divide-by zero */
if (delta_reference || delta_delivered)
delivered_perf = (reference_perf * delta_delivered) /
delta_reference;
else
delivered_perf = cpu->perf_ctrls.desired_perf;
return cppc_cpufreq_perf_to_khz(cpu, delivered_perf);
}
static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
{
struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
struct cppc_cpudata *cpu = all_cpu_data[cpunum];
int ret;
ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t0);
if (ret)
return ret;
udelay(2); /* 2usec delay between sampling */
ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t1);
if (ret)
return ret;
return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);
}
static struct cpufreq_driver cppc_cpufreq_driver = {
.flags = CPUFREQ_CONST_LOOPS,
.verify = cppc_verify_policy,
.target = cppc_cpufreq_set_target,
.get = cppc_cpufreq_get_rate,
.init = cppc_cpufreq_cpu_init,
.stop_cpu = cppc_cpufreq_stop_cpu,
.name = "cppc_cpufreq",