[PATCH v2] cpufreq / CPPC: Add cpuinfo_cur_freq support for CPPC
From: George Cherian <hidden>
Date: 2018-06-15 10:03:45
Also in:
lkml
Subsystem:
cpu frequency drivers - cppc cpufreq, cpu frequency scaling framework, the rest · Maintainers:
"Rafael J. Wysocki", Viresh Kumar, Linus Torvalds
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 to the cpufreq->get method. Signed-off-by: George Cherian <redacted> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/cppc_cpufreq.c | 71 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+)
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 3464580..3fe7625 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c@@ -296,10 +296,81 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy) return ret; } +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; + if (fb_ctrs_t1.reference > fb_ctrs_t0.reference) { + delta_reference = fb_ctrs_t1.reference - fb_ctrs_t0.reference; + } else { + /* + * Counters would have wrapped-around + * We also need to find whether the low level fw + * maintains 32 bit or 64 bit counters, to calculate + * the correct delta. + */ + if (fb_ctrs_t0.reference > (~(u32)0)) + delta_reference = (~((u64)0) - fb_ctrs_t0.reference) + + fb_ctrs_t1.reference; + else + delta_reference = (~((u32)0) - fb_ctrs_t0.reference) + + fb_ctrs_t1.reference; + } + + if (fb_ctrs_t1.delivered > fb_ctrs_t0.delivered) { + delta_delivered = fb_ctrs_t1.delivered - fb_ctrs_t0.delivered; + } else { + /* + * Counters would have wrapped-around + * We also need to find whether the low level fw + * maintains 32 bit or 64 bit counters, to calculate + * the correct delta. + */ + if (fb_ctrs_t0.delivered > (~(u32)0)) + delta_delivered = (~((u64)0) - fb_ctrs_t0.delivered) + + fb_ctrs_t1.delivered; + else + delta_delivered = (~((u32)0) - fb_ctrs_t0.delivered) + + fb_ctrs_t1.delivered; + } + + if (delta_reference) /* Check to avoid divide-by zero */ + delivered_perf = (reference_perf * delta_delivered) / + delta_reference; + else + delivered_perf = reference_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",
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2.7.4