linux/arch/x86/kernel/acpi/cppc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * cppc.c: CPPC Interface for x86
 * Copyright (c) 2016, Intel Corporation.
 */

#include <acpi/cppc_acpi.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/topology.h>

#define CPPC_HIGHEST_PERF_PREFCORE	166

enum amd_pref_core {
	AMD_PREF_CORE_UNKNOWN = 0,
	AMD_PREF_CORE_SUPPORTED,
	AMD_PREF_CORE_UNSUPPORTED,
};
static enum amd_pref_core amd_pref_core_detected;
static u64 boost_numerator;

/* Refer to drivers/acpi/cppc_acpi.c for the description of functions */

bool cpc_supported_by_cpu(void)
{
	switch (boot_cpu_data.x86_vendor) {
	case X86_VENDOR_AMD:
	case X86_VENDOR_HYGON:
		if (boot_cpu_data.x86 == 0x19 && ((boot_cpu_data.x86_model <= 0x0f) ||
		    (boot_cpu_data.x86_model >= 0x20 && boot_cpu_data.x86_model <= 0x2f)))
			return true;
		else if (boot_cpu_data.x86 == 0x17 &&
			 boot_cpu_data.x86_model >= 0x30 && boot_cpu_data.x86_model <= 0x7f)
			return true;
		return boot_cpu_has(X86_FEATURE_CPPC);
	}
	return false;
}

bool cpc_ffh_supported(void)
{
	return true;
}

int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
{
	int err;

	err = rdmsrl_safe_on_cpu(cpunum, reg->address, val);
	if (!err) {
		u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
				       reg->bit_offset);

		*val &= mask;
		*val >>= reg->bit_offset;
	}
	return err;
}

int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
{
	u64 rd_val;
	int err;

	err = rdmsrl_safe_on_cpu(cpunum, reg->address, &rd_val);
	if (!err) {
		u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
				       reg->bit_offset);

		val <<= reg->bit_offset;
		val &= mask;
		rd_val &= ~mask;
		rd_val |= val;
		err = wrmsrl_safe_on_cpu(cpunum, reg->address, rd_val);
	}
	return err;
}

static void amd_set_max_freq_ratio(void)
{
	struct cppc_perf_caps perf_caps;
	u64 numerator, nominal_perf;
	u64 perf_ratio;
	int rc;

	rc = cppc_get_perf_caps(0, &perf_caps);
	if (rc) {
		pr_warn("Could not retrieve perf counters (%d)\n", rc);
		return;
	}

	rc = amd_get_boost_ratio_numerator(0, &numerator);
	if (rc) {
		pr_warn("Could not retrieve highest performance (%d)\n", rc);
		return;
	}
	nominal_perf = perf_caps.nominal_perf;

	if (!nominal_perf) {
		pr_warn("Could not retrieve nominal performance\n");
		return;
	}

	/* midpoint between max_boost and max_P */
	perf_ratio = (div_u64(numerator * SCHED_CAPACITY_SCALE, nominal_perf) + SCHED_CAPACITY_SCALE) >> 1;

	freq_invariance_set_perf_ratio(perf_ratio, false);
}

static DEFINE_MUTEX(freq_invariance_lock);

void init_freq_invariance_cppc(void)
{
	static bool init_done;

	if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
		return;

	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
		return;

	mutex_lock(&freq_invariance_lock);
	if (!init_done)
		amd_set_max_freq_ratio();
	init_done = true;
	mutex_unlock(&freq_invariance_lock);
}

/*
 * Get the highest performance register value.
 * @cpu: CPU from which to get highest performance.
 * @highest_perf: Return address for highest performance value.
 *
 * Return: 0 for success, negative error code otherwise.
 */
int amd_get_highest_perf(unsigned int cpu, u32 *highest_perf)
{
	u64 val;
	int ret;

	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
		ret = rdmsrl_safe_on_cpu(cpu, MSR_AMD_CPPC_CAP1, &val);
		if (ret)
			goto out;

		val = AMD_CPPC_HIGHEST_PERF(val);
	} else {
		ret = cppc_get_highest_perf(cpu, &val);
		if (ret)
			goto out;
	}

	WRITE_ONCE(*highest_perf, (u32)val);
out:
	return ret;
}
EXPORT_SYMBOL_GPL(amd_get_highest_perf);

/**
 * amd_detect_prefcore: Detect if CPUs in the system support preferred cores
 * @detected: Output variable for the result of the detection.
 *
 * Determine whether CPUs in the system support preferred cores. On systems
 * that support preferred cores, different highest perf values will be found
 * on different cores. On other systems, the highest perf value will be the
 * same on all cores.
 *
 * The result of the detection will be stored in the 'detected' parameter.
 *
 * Return: 0 for success, negative error code otherwise
 */
int amd_detect_prefcore(bool *detected)
{
	int cpu, count = 0;
	u64 highest_perf[2] = {0};

	if (WARN_ON(!detected))
		return -EINVAL;

	switch (amd_pref_core_detected) {
	case AMD_PREF_CORE_SUPPORTED:
		*detected = true;
		return 0;
	case AMD_PREF_CORE_UNSUPPORTED:
		*detected = false;
		return 0;
	default:
		break;
	}

	for_each_present_cpu(cpu) {
		u32 tmp;
		int ret;

		ret = amd_get_highest_perf(cpu, &tmp);
		if (ret)
			return ret;

		if (!count || (count == 1 && tmp != highest_perf[0]))
			highest_perf[count++] = tmp;

		if (count == 2)
			break;
	}

	*detected = (count == 2);
	boost_numerator = highest_perf[0];

	amd_pref_core_detected = *detected ? AMD_PREF_CORE_SUPPORTED :
					     AMD_PREF_CORE_UNSUPPORTED;

	pr_debug("AMD CPPC preferred core is %ssupported (highest perf: 0x%llx)\n",
		 *detected ? "" : "un", highest_perf[0]);

	return 0;
}
EXPORT_SYMBOL_GPL(amd_detect_prefcore);

/**
 * amd_get_boost_ratio_numerator: Get the numerator to use for boost ratio calculation
 * @cpu: CPU to get numerator for.
 * @numerator: Output variable for numerator.
 *
 * Determine the numerator to use for calculating the boost ratio on
 * a CPU. On systems that support preferred cores, this will be a hardcoded
 * value. On other systems this will the highest performance register value.
 *
 * If booting the system with amd-pstate enabled but preferred cores disabled then
 * the correct boost numerator will be returned to match hardware capabilities
 * even if the preferred cores scheduling hints are not enabled.
 *
 * Return: 0 for success, negative error code otherwise.
 */
int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
{
	bool prefcore;
	int ret;

	ret = amd_detect_prefcore(&prefcore);
	if (ret)
		return ret;

	/* without preferred cores, return the highest perf register value */
	if (!prefcore) {
		*numerator = boost_numerator;
		return 0;
	}
	*numerator = CPPC_HIGHEST_PERF_PREFCORE;

	return 0;
}
EXPORT_SYMBOL_GPL(amd_get_boost_ratio_numerator);