linux/drivers/cpufreq/cppc_cpufreq.c

385 lines
9.5 KiB
C

/*
* CPPC (Collaborative Processor Performance Control) driver for
* interfacing with the CPUfreq layer and governors. See
* cppc_acpi.c for CPPC specific methods.
*
* (C) Copyright 2014, 2015 Linaro Ltd.
* Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#define pr_fmt(fmt) "CPPC Cpufreq:" fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/dmi.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <asm/unaligned.h>
#include <acpi/cppc_acpi.h>
/* Minimum struct length needed for the DMI processor entry we want */
#define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
/* Offest in the DMI processor structure for the max frequency */
#define DMI_PROCESSOR_MAX_SPEED 0x14
/*
* These structs contain information parsed from per CPU
* ACPI _CPC structures.
* e.g. For each CPU the highest, lowest supported
* performance capabilities, desired performance level
* requested etc.
*/
static struct cppc_cpudata **all_cpu_data;
/* Callback function used to retrieve the max frequency from DMI */
static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
{
const u8 *dmi_data = (const u8 *)dm;
u16 *mhz = (u16 *)private;
if (dm->type == DMI_ENTRY_PROCESSOR &&
dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
u16 val = (u16)get_unaligned((const u16 *)
(dmi_data + DMI_PROCESSOR_MAX_SPEED));
*mhz = val > *mhz ? val : *mhz;
}
}
/* Look up the max frequency in DMI */
static u64 cppc_get_dmi_max_khz(void)
{
u16 mhz = 0;
dmi_walk(cppc_find_dmi_mhz, &mhz);
/*
* Real stupid fallback value, just in case there is no
* actual value set.
*/
mhz = mhz ? mhz : 1;
return (1000 * mhz);
}
/*
* If CPPC lowest_freq and nominal_freq registers are exposed then we can
* use them to convert perf to freq and vice versa
*
* If the perf/freq point lies between Nominal and Lowest, we can treat
* (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
* and extrapolate the rest
* For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
*/
static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu,
unsigned int perf)
{
static u64 max_khz;
struct cppc_perf_caps *caps = &cpu->perf_caps;
u64 mul, div;
if (caps->lowest_freq && caps->nominal_freq) {
if (perf >= caps->nominal_perf) {
mul = caps->nominal_freq;
div = caps->nominal_perf;
} else {
mul = caps->nominal_freq - caps->lowest_freq;
div = caps->nominal_perf - caps->lowest_perf;
}
} else {
if (!max_khz)
max_khz = cppc_get_dmi_max_khz();
mul = max_khz;
div = cpu->perf_caps.highest_perf;
}
return (u64)perf * mul / div;
}
static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu,
unsigned int freq)
{
static u64 max_khz;
struct cppc_perf_caps *caps = &cpu->perf_caps;
u64 mul, div;
if (caps->lowest_freq && caps->nominal_freq) {
if (freq >= caps->nominal_freq) {
mul = caps->nominal_perf;
div = caps->nominal_freq;
} else {
mul = caps->lowest_perf;
div = caps->lowest_freq;
}
} else {
if (!max_khz)
max_khz = cppc_get_dmi_max_khz();
mul = cpu->perf_caps.highest_perf;
div = max_khz;
}
return (u64)freq * mul / div;
}
static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
struct cppc_cpudata *cpu;
struct cpufreq_freqs freqs;
u32 desired_perf;
int ret = 0;
cpu = all_cpu_data[policy->cpu];
desired_perf = cppc_cpufreq_khz_to_perf(cpu, target_freq);
/* Return if it is exactly the same perf */
if (desired_perf == cpu->perf_ctrls.desired_perf)
return ret;
cpu->perf_ctrls.desired_perf = desired_perf;
freqs.old = policy->cur;
freqs.new = target_freq;
cpufreq_freq_transition_begin(policy, &freqs);
ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
cpufreq_freq_transition_end(policy, &freqs, ret != 0);
if (ret)
pr_debug("Failed to set target on CPU:%d. ret:%d\n",
cpu->cpu, ret);
return ret;
}
static int cppc_verify_policy(struct cpufreq_policy *policy)
{
cpufreq_verify_within_cpu_limits(policy);
return 0;
}
static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
{
int cpu_num = policy->cpu;
struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
int ret;
cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
if (ret)
pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
cpu->perf_caps.lowest_perf, cpu_num, ret);
}
/*
* The PCC subspace describes the rate at which platform can accept commands
* on the shared PCC channel (including READs which do not count towards freq
* trasition requests), so ideally we need to use the PCC values as a fallback
* if we don't have a platform specific transition_delay_us
*/
#ifdef CONFIG_ARM64
#include <asm/cputype.h>
static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
{
unsigned long implementor = read_cpuid_implementor();
unsigned long part_num = read_cpuid_part_number();
unsigned int delay_us = 0;
switch (implementor) {
case ARM_CPU_IMP_QCOM:
switch (part_num) {
case QCOM_CPU_PART_FALKOR_V1:
case QCOM_CPU_PART_FALKOR:
delay_us = 10000;
break;
default:
delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
break;
}
break;
default:
delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
break;
}
return delay_us;
}
#else
static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
{
return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
}
#endif
static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
struct cppc_cpudata *cpu;
unsigned int cpu_num = policy->cpu;
int ret = 0;
cpu = all_cpu_data[policy->cpu];
cpu->cpu = cpu_num;
ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
if (ret) {
pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
cpu_num, ret);
return ret;
}
/* Convert the lowest and nominal freq from MHz to KHz */
cpu->perf_caps.lowest_freq *= 1000;
cpu->perf_caps.nominal_freq *= 1000;
/*
* Set min to lowest nonlinear perf to avoid any efficiency penalty (see
* Section 8.4.7.1.1.5 of ACPI 6.1 spec)
*/
policy->min = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_nonlinear_perf);
policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
/*
* Set cpuinfo.min_freq to Lowest to make the full range of performance
* available if userspace wants to use any perf between lowest & lowest
* nonlinear perf
*/
policy->cpuinfo.min_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_perf);
policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
policy->shared_type = cpu->shared_type;
if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
int i;
cpumask_copy(policy->cpus, cpu->shared_cpu_map);
for_each_cpu(i, policy->cpus) {
if (unlikely(i == policy->cpu))
continue;
memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
sizeof(cpu->perf_caps));
}
} else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
/* Support only SW_ANY for now. */
pr_debug("Unsupported CPU co-ord type\n");
return -EFAULT;
}
cpu->cur_policy = policy;
/* Set policy->cur to max now. The governors will adjust later. */
policy->cur = cppc_cpufreq_perf_to_khz(cpu,
cpu->perf_caps.highest_perf);
cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
if (ret)
pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
cpu->perf_caps.highest_perf, cpu_num, ret);
return ret;
}
static struct cpufreq_driver cppc_cpufreq_driver = {
.flags = CPUFREQ_CONST_LOOPS,
.verify = cppc_verify_policy,
.target = cppc_cpufreq_set_target,
.init = cppc_cpufreq_cpu_init,
.stop_cpu = cppc_cpufreq_stop_cpu,
.name = "cppc_cpufreq",
};
static int __init cppc_cpufreq_init(void)
{
int i, ret = 0;
struct cppc_cpudata *cpu;
if (acpi_disabled)
return -ENODEV;
all_cpu_data = kcalloc(num_possible_cpus(), sizeof(void *),
GFP_KERNEL);
if (!all_cpu_data)
return -ENOMEM;
for_each_possible_cpu(i) {
all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
if (!all_cpu_data[i])
goto out;
cpu = all_cpu_data[i];
if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
goto out;
}
ret = acpi_get_psd_map(all_cpu_data);
if (ret) {
pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
goto out;
}
ret = cpufreq_register_driver(&cppc_cpufreq_driver);
if (ret)
goto out;
return ret;
out:
for_each_possible_cpu(i) {
cpu = all_cpu_data[i];
if (!cpu)
break;
free_cpumask_var(cpu->shared_cpu_map);
kfree(cpu);
}
kfree(all_cpu_data);
return -ENODEV;
}
static void __exit cppc_cpufreq_exit(void)
{
struct cppc_cpudata *cpu;
int i;
cpufreq_unregister_driver(&cppc_cpufreq_driver);
for_each_possible_cpu(i) {
cpu = all_cpu_data[i];
free_cpumask_var(cpu->shared_cpu_map);
kfree(cpu);
}
kfree(all_cpu_data);
}
module_exit(cppc_cpufreq_exit);
MODULE_AUTHOR("Ashwin Chaugule");
MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
MODULE_LICENSE("GPL");
late_initcall(cppc_cpufreq_init);
static const struct acpi_device_id cppc_acpi_ids[] = {
{ACPI_PROCESSOR_DEVICE_HID, },
{}
};
MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);