diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/acpi/cppc_acpi.c | 46 | ||||
| -rw-r--r-- | drivers/cpufreq/cppc_cpufreq.c | 1 |
2 files changed, 45 insertions, 2 deletions
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 5623fca54ca1..6c54a8f16706 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -85,7 +85,7 @@ static void __iomem *pcc_comm_addr; static int pcc_subspace_idx = -1; static bool pcc_channel_acquired; static ktime_t deadline; -static unsigned int pcc_mpar, pcc_mrtt; +static unsigned int pcc_mpar, pcc_mrtt, pcc_nominal; /* pcc mapped address + header size + offset within PCC subspace */ #define GET_PCC_VADDR(offs) (pcc_comm_addr + 0x8 + (offs)) @@ -473,7 +473,6 @@ static int register_pcc_channel(int pcc_subspace_idx) return -ENODEV; } - /* * cppc_ss->latency is just a Nominal value. In reality * the remote processor could be much slower to reply. @@ -483,6 +482,7 @@ static int register_pcc_channel(int pcc_subspace_idx) deadline = ns_to_ktime(usecs_lat * NSEC_PER_USEC); pcc_mrtt = cppc_ss->min_turnaround_time; pcc_mpar = cppc_ss->max_access_rate; + pcc_nominal = cppc_ss->latency; pcc_comm_addr = acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length); if (!pcc_comm_addr) { @@ -1048,3 +1048,45 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls) return ret; } EXPORT_SYMBOL_GPL(cppc_set_perf); + +/** + * cppc_get_transition_latency - returns frequency transition latency in ns + * + * ACPI CPPC does not explicitly specifiy how a platform can specify the + * transition latency for perfromance change requests. The closest we have + * is the timing information from the PCCT tables which provides the info + * on the number and frequency of PCC commands the platform can handle. + */ +unsigned int cppc_get_transition_latency(int cpu_num) +{ + /* + * Expected transition latency is based on the PCCT timing values + * Below are definition from ACPI spec: + * pcc_nominal- Expected latency to process a command, in microseconds + * pcc_mpar - The maximum number of periodic requests that the subspace + * channel can support, reported in commands per minute. 0 + * indicates no limitation. + * pcc_mrtt - The minimum amount of time that OSPM must wait after the + * completion of a command before issuing the next command, + * in microseconds. + */ + unsigned int latency_ns = 0; + struct cpc_desc *cpc_desc; + struct cpc_register_resource *desired_reg; + + cpc_desc = per_cpu(cpc_desc_ptr, cpu_num); + if (!cpc_desc) + return CPUFREQ_ETERNAL; + + desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF]; + if (!CPC_IN_PCC(desired_reg)) + return CPUFREQ_ETERNAL; + + if (pcc_mpar) + latency_ns = 60 * (1000 * 1000 * 1000 / pcc_mpar); + + latency_ns = max(latency_ns, (pcc_nominal + pcc_mrtt) * 1000); + + return latency_ns; +} +EXPORT_SYMBOL_GPL(cppc_get_transition_latency); diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c index 8882b8e2ecd0..e6a33596dea3 100644 --- a/drivers/cpufreq/cppc_cpufreq.c +++ b/drivers/cpufreq/cppc_cpufreq.c @@ -98,6 +98,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy) policy->max = cpu->perf_caps.highest_perf; policy->cpuinfo.min_freq = policy->min; policy->cpuinfo.max_freq = policy->max; + policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num); policy->shared_type = cpu->shared_type; if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) |