[PATCH v9 06/13] cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors

Perry Yuan
2022-12-25T16:36:05Z

From: Perry Yuan <Perry.Yuan@amd.com>

Add EPP driver support for AMD SoCs which support a dedicated MSR for
CPPC. EPP is used by the DPM controller to configure the frequency that
a core operates at during short periods of activity.

The SoC EPP targets are configured on a scale from 0 to 255 where 0
represents maximum performance and 255 represents maximum efficiency.

The amd-pstate driver exports profile string names to userspace that are
tied to specific EPP values.

The balance_performance string (0x80) provides the best balance for
efficiency versus power on most systems, but users can choose other
strings to meet their needs as well.

$ cat /sys/devices/system/cpu/cpufreq/policy0/energy_performance_available_preferences
default performance balance_performance balance_power power

$ cat /sys/devices/system/cpu/cpufreq/policy0/energy_performance_preference
balance_performance

To enable the driver,it needs to add `amd_pstate=active` to kernel
command line and kernel will load the active mode epp driver

Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
drivers/cpufreq/amd-pstate.c | 374 ++++++++++++++++++++++++++++++++++-
include/linux/amd-pstate.h | 10 +
2 files changed, 378 insertions(+), 6 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 65c16edbbb20..779bbb58d909 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -59,7 +59,9 @@
* we disable it by default to go acpi-cpufreq on these processors and add a
* module parameter to be able to enable it manually for debugging.
*/
+static struct cpufreq_driver *default_pstate_driver;
static struct cpufreq_driver amd_pstate_driver;
+static struct cpufreq_driver amd_pstate_epp_driver;
static int cppc_state = AMD_PSTATE_DISABLE;

static inline int get_mode_idx_from_str(const char *str, size_t size)
@@ -73,6 +75,114 @@ static inline int get_mode_idx_from_str(const char *str, size_t size)
return -EINVAL;
}

+static DEFINE_MUTEX(amd_pstate_limits_lock);
+static DEFINE_MUTEX(amd_pstate_driver_lock);
+
+static s16 amd_pstate_get_epp(struct amd_cpudata *cpudata, u64 cppc_req_cached)
+{
+ u64 epp;
+ int ret;
+
+ if (boot_cpu_has(X86_FEATURE_CPPC)) {
+ if (!cppc_req_cached) {
+ epp = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ,
+ &cppc_req_cached);
+ if (epp)
+ return epp;
+ }
+ epp = (cppc_req_cached >> 24) & 0xFF;
+ } else {
+ ret = cppc_get_epp_perf(cpudata->cpu, &epp);
+ if (ret < 0) {
+ pr_debug("Could not retrieve energy perf value (%d)\n", ret);
+ return -EIO;
+ }
+ }
+
+ return (s16)(epp & 0xff);
+}
+
+static int amd_pstate_get_energy_pref_index(struct amd_cpudata *cpudata)
+{
+ s16 epp;
+ int index = -EINVAL;
+
+ epp = amd_pstate_get_epp(cpudata, 0);
+ if (epp < 0)
+ return epp;
+
+ switch (epp) {
+ case HWP_EPP_PERFORMANCE:
+ index = EPP_INDEX_PERFORMANCE;
+ break;
+ case HWP_EPP_BALANCE_PERFORMANCE:
+ index = EPP_INDEX_BALANCE_PERFORMANCE;
+ break;
+ case HWP_EPP_BALANCE_POWERSAVE:
+ index = EPP_INDEX_BALANCE_POWERSAVE;
+ break;
+ case HWP_EPP_POWERSAVE:
+ index = EPP_INDEX_POWERSAVE;
+ break;
+ default:
+ break;
+ }
+
+ return index;
+}
+
+static int amd_pstate_set_epp(struct amd_cpudata *cpudata, u32 epp)
+{
+ int ret;
+ struct cppc_perf_ctrls perf_ctrls;
+
+ if (boot_cpu_has(X86_FEATURE_CPPC)) {
+ u64 value = READ_ONCE(cpudata->cppc_req_cached);
+
+ value &= ~GENMASK_ULL(31, 24);
+ value |= (u64)epp << 24;
+ WRITE_ONCE(cpudata->cppc_req_cached, value);
+
+ ret = wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
+ if (!ret)
+ cpudata->epp_cached = epp;
+ } else {
+ perf_ctrls.energy_perf = epp;
+ ret = cppc_set_epp_perf(cpudata->cpu, &perf_ctrls, 1);
+ if (ret) {
+ pr_debug("failed to set energy perf value (%d)\n", ret);
+ return ret;
+ }
+ cpudata->epp_cached = epp;
+ }
+
+ return ret;
+}
+
+static int amd_pstate_set_energy_pref_index(struct amd_cpudata *cpudata,
+ int pref_index)
+{
+ int epp = -EINVAL;
+ int ret;
+
+ if (!pref_index) {
+ pr_debug("EPP pref_index is invalid\n");
+ return -EINVAL;
+ }
+
+ if (epp == -EINVAL)
+ epp = epp_values[pref_index];
+
+ if (epp > 0 && cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
+ pr_debug("EPP cannot be set under performance policy\n");
+ return -EBUSY;
+ }
+
+ ret = amd_pstate_set_epp(cpudata, epp);
+
+ return ret;
+}
+
static inline int pstate_enable(bool enable)
{
return wrmsrl_safe(MSR_AMD_CPPC_ENABLE, enable);
@@ -81,11 +191,21 @@ static inline int pstate_enable(bool enable)
static int cppc_enable(bool enable)
{
int cpu, ret = 0;
+ struct cppc_perf_ctrls perf_ctrls;

for_each_present_cpu(cpu) {
ret = cppc_set_enable(cpu, enable);
if (ret)
return ret;
+
+ /* Enable autonomous mode for EPP */
+ if (cppc_state == AMD_PSTATE_ACTIVE) {
+ /* Set desired perf as zero to allow EPP firmware control */
+ perf_ctrls.desired_perf = 0;
+ ret = cppc_set_perf(cpu, &perf_ctrls);
+ if (ret)
+ return ret;
+ }
}

return ret;
@@ -429,7 +549,7 @@ static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
return;

cpudata->boost_supported = true;
- amd_pstate_driver.boost_enabled = true;
+ default_pstate_driver->boost_enabled = true;
}

static void amd_perf_ctl_reset(unsigned int cpu)
@@ -603,10 +723,61 @@ static ssize_t show_amd_pstate_highest_perf(struct cpufreq_policy *policy,
return sprintf(&buf[0], "%u\n", perf);
}

+static ssize_t show_energy_performance_available_preferences(
+ struct cpufreq_policy *policy, char *buf)
+{
+ int i = 0;
+ int offset = 0;
+
+ while (energy_perf_strings[i] != NULL)
+ offset += sysfs_emit_at(buf, offset, "%s ", energy_perf_strings[i++]);
+
+ sysfs_emit_at(buf, offset, "\n");
+
+ return offset;
+}
+
+static ssize_t store_energy_performance_preference(
+ struct cpufreq_policy *policy, const char *buf, size_t count)
+{
+ struct amd_cpudata *cpudata = policy->driver_data;
+ char str_preference[21];
+ ssize_t ret;
+
+ ret = sscanf(buf, "%20s", str_preference);
+ if (ret != 1)
+ return -EINVAL;
+
+ ret = match_string(energy_perf_strings, -1, str_preference);
+ if (ret < 0)
+ return -EINVAL;
+
+ mutex_lock(&amd_pstate_limits_lock);
+ ret = amd_pstate_set_energy_pref_index(cpudata, ret);
+ mutex_unlock(&amd_pstate_limits_lock);
+
+ return ret ?: count;
+}
+
+static ssize_t show_energy_performance_preference(
+ struct cpufreq_policy *policy, char *buf)
+{
+ struct amd_cpudata *cpudata = policy->driver_data;
+ int preference;
+
+ preference = amd_pstate_get_energy_pref_index(cpudata);
+ if (preference < 0)
+ return preference;
+
+ return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
+}
+
cpufreq_freq_attr_ro(amd_pstate_max_freq);
cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);

cpufreq_freq_attr_ro(amd_pstate_highest_perf);
+cpufreq_freq_attr_rw(energy_performance_preference);
+cpufreq_freq_attr_ro(energy_performance_available_preferences);

static struct freq_attr *amd_pstate_attr[] = {
&amd_pstate_max_freq,
@@ -615,6 +786,181 @@ static struct freq_attr *amd_pstate_attr[] = {
NULL,
};

+static struct freq_attr *amd_pstate_epp_attr[] = {
+ &amd_pstate_max_freq,
+ &amd_pstate_lowest_nonlinear_freq,
+ &amd_pstate_highest_perf,
+ &energy_performance_preference,
+ &energy_performance_available_preferences,
+ NULL,
+};
+
+static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
+{
+ int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
+ struct amd_cpudata *cpudata;
+ struct device *dev;
+ int rc;
+ u64 value;
+
+ dev = get_cpu_device(policy->cpu);
+ if (!dev)
+ goto free_cpudata1;
+
+ cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL);
+ if (!cpudata)
+ return -ENOMEM;
+
+ cpudata->cpu = policy->cpu;
+ cpudata->epp_policy = 0;
+
+ rc = amd_pstate_init_perf(cpudata);
+ if (rc)
+ goto free_cpudata1;
+
+ min_freq = amd_get_min_freq(cpudata);
+ max_freq = amd_get_max_freq(cpudata);
+ nominal_freq = amd_get_nominal_freq(cpudata);
+ lowest_nonlinear_freq = amd_get_lowest_nonlinear_freq(cpudata);
+ if (min_freq < 0 || max_freq < 0 || min_freq > max_freq) {
+ dev_err(dev, "min_freq(%d) or max_freq(%d) value is incorrect\n",
+ min_freq, max_freq);
+ ret = -EINVAL;
+ goto free_cpudata1;
+ }
+
+ policy->cpuinfo.min_freq = min_freq;
+ policy->cpuinfo.max_freq = max_freq;
+ /* It will be updated by governor */
+ policy->cur = policy->cpuinfo.min_freq;
+
+ /* Initial processor data capability frequencies */
+ cpudata->max_freq = max_freq;
+ cpudata->min_freq = min_freq;
+ cpudata->nominal_freq = nominal_freq;
+ cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;
+
+ policy->driver_data = cpudata;
+
+ cpudata->epp_cached = amd_pstate_get_epp(cpudata, value);
+
+ policy->min = policy->cpuinfo.min_freq;
+ policy->max = policy->cpuinfo.max_freq;
+
+ /*
+ * Set the policy to powersave to provide a valid fallback value in case
+ * the default cpufreq governor is neither powersave nor performance.
+ */
+ policy->policy = CPUFREQ_POLICY_POWERSAVE;
+
+ if (boot_cpu_has(X86_FEATURE_CPPC)) {
+ policy->fast_switch_possible = true;
+ ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &value);
+ if (ret)
+ return ret;
+ WRITE_ONCE(cpudata->cppc_req_cached, value);
+
+ ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1, &value);
+ if (ret)
+ return ret;
+ WRITE_ONCE(cpudata->cppc_cap1_cached, value);
+ }
+ amd_pstate_boost_init(cpudata);
+
+ return 0;
+
+free_cpudata1:
+ kfree(cpudata);
+ return ret;
+}
+
+static int amd_pstate_epp_cpu_exit(struct cpufreq_policy *policy)
+{
+ pr_debug("CPU %d exiting\n", policy->cpu);
+ policy->fast_switch_possible = false;
+ return 0;
+}
+
+static void amd_pstate_epp_init(unsigned int cpu)
+{
+ struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+ struct amd_cpudata *cpudata = policy->driver_data;
+ u32 max_perf, min_perf;
+ u64 value;
+ s16 epp;
+
+ max_perf = READ_ONCE(cpudata->highest_perf);
+ min_perf = READ_ONCE(cpudata->lowest_perf);
+
+ value = READ_ONCE(cpudata->cppc_req_cached);
+
+ if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
+ min_perf = max_perf;
+
+ /* Initial min/max values for CPPC Performance Controls Register */
+ value &= ~AMD_CPPC_MIN_PERF(~0L);
+ value |= AMD_CPPC_MIN_PERF(min_perf);
+
+ value &= ~AMD_CPPC_MAX_PERF(~0L);
+ value |= AMD_CPPC_MAX_PERF(max_perf);
+
+ /* CPPC EPP feature require to set zero to the desire perf bit */
+ value &= ~AMD_CPPC_DES_PERF(~0L);
+ value |= AMD_CPPC_DES_PERF(0);
+
+ if (cpudata->epp_policy == cpudata->policy)
+ goto skip_epp;
+
+ cpudata->epp_policy = cpudata->policy;
+
+ if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
+ epp = amd_pstate_get_epp(cpudata, value);
+ if (epp < 0)
+ goto skip_epp;
+ /* force the epp value to be zero for performance policy */
+ epp = 0;
+ } else {
+ /* Get BIOS pre-defined epp value */
+ epp = amd_pstate_get_epp(cpudata, value);
+ if (epp)
+ goto skip_epp;
+ }
+ /* Set initial EPP value */
+ if (boot_cpu_has(X86_FEATURE_CPPC)) {
+ value &= ~GENMASK_ULL(31, 24);
+ value |= (u64)epp << 24;
+ }
+
+skip_epp:
+ WRITE_ONCE(cpudata->cppc_req_cached, value);
+ amd_pstate_set_epp(cpudata, epp);
+ cpufreq_cpu_put(policy);
+}
+
+static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy)
+{
+ struct amd_cpudata *cpudata = policy->driver_data;
+
+ if (!policy->cpuinfo.max_freq)
+ return -ENODEV;
+
+ pr_debug("set_policy: cpuinfo.max %u policy->max %u\n",
+ policy->cpuinfo.max_freq, policy->max);
+
+ cpudata->policy = policy->policy;
+
+ amd_pstate_epp_init(policy->cpu);
+
+ return 0;
+}
+
+static int amd_pstate_epp_verify_policy(struct cpufreq_policy_data *policy)
+{
+ cpufreq_verify_within_cpu_limits(policy);
+ pr_debug("policy_max =%d, policy_min=%d\n", policy->max, policy->min);
+ return 0;
+}
+
static struct cpufreq_driver amd_pstate_driver = {
.flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS,
.verify = amd_pstate_verify,
@@ -628,6 +974,16 @@ static struct cpufreq_driver amd_pstate_driver = {
.attr = amd_pstate_attr,
};

+static struct cpufreq_driver amd_pstate_epp_driver = {
+ .flags = CPUFREQ_CONST_LOOPS,
+ .verify = amd_pstate_epp_verify_policy,
+ .setpolicy = amd_pstate_epp_set_policy,
+ .init = amd_pstate_epp_cpu_init,
+ .exit = amd_pstate_epp_cpu_exit,
+ .name = "amd_pstate_epp",
+ .attr = amd_pstate_epp_attr,
+};
+
static int __init amd_pstate_init(void)
{
int ret;
@@ -656,7 +1012,8 @@ static int __init amd_pstate_init(void)
/* capability check */
if (boot_cpu_has(X86_FEATURE_CPPC)) {
pr_debug("AMD CPPC MSR based functionality is supported\n");
- amd_pstate_driver.adjust_perf = amd_pstate_adjust_perf;
+ if (cppc_state == AMD_PSTATE_PASSIVE)
+ default_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
} else {
pr_debug("AMD CPPC shared memory based functionality is supported\n");
static_call_update(amd_pstate_enable, cppc_enable);
@@ -667,14 +1024,13 @@ static int __init amd_pstate_init(void)
/* enable amd pstate feature */
ret = amd_pstate_enable(true);
if (ret) {
- pr_err("failed to enable amd-pstate with return %d\n", ret);
+ pr_err("failed to enable with return %d\n", ret);
return ret;
}

- ret = cpufreq_register_driver(&amd_pstate_driver);
+ ret = cpufreq_register_driver(default_pstate_driver);
if (ret)
- pr_err("failed to register amd_pstate_driver with return %d\n",
- ret);
+ pr_err("failed to register with return %d\n", ret);

return ret;
}
@@ -696,6 +1052,12 @@ static int __init amd_pstate_param(char *str)
if (cppc_state == AMD_PSTATE_DISABLE)
pr_info("driver is explicitly disabled\n");

+ if (cppc_state == AMD_PSTATE_ACTIVE)
+ default_pstate_driver = &amd_pstate_epp_driver;
+
+ if (cppc_state == AMD_PSTATE_PASSIVE)
+ default_pstate_driver = &amd_pstate_driver;
+
return 0;
}

diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
index dae2ce0f6735..8341a2a2948a 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -47,6 +47,10 @@ struct amd_aperf_mperf {
* @prev: Last Aperf/Mperf/tsc count value read from register
* @freq: current cpu frequency value
* @boost_supported: check whether the Processor or SBIOS supports boost mode
+ * @epp_policy: Last saved policy used to set energy-performance preference
+ * @epp_cached: Cached CPPC energy-performance preference value
+ * @policy: Cpufreq policy value
+ * @cppc_cap1_cached Cached MSR_AMD_CPPC_CAP1 register value
*
* The amd_cpudata is key private data for each CPU thread in AMD P-State, and
* represents all the attributes and goals that AMD P-State requests at runtime.
@@ -72,6 +76,12 @@ struct amd_cpudata {

u64 freq;
bool boost_supported;
+
+ /* EPP feature related attributes*/
+ s16 epp_policy;
+ s16 epp_cached;
+ u32 policy;
+ u64 cppc_cap1_cached;
};

/*
--
2.34.1