[RFC v3 3/4] platform/x86/amd: dptc: Add platform profile support
From: Antheas Kapenekakis
Date: Sat Mar 07 2026 - 06:57:00 EST
Register a platform_profile handler so the driver exposes standard
power profiles (low-power, balanced, performance, max-power) alongside
the manual tunable interface. max-power is only supplied when the
performance profile's preset values are below the tunable limits.
When a non-custom profile is active, parameter writes are blocked
(-EPERM) and current_value reflects the profile's preset values.
Selecting the "custom" profile returns control to the user for manual
staging and committing. On resume, the active profile is automatically
re-applied.
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Antheas Kapenekakis <lkml@xxxxxxxxxxx>
---
drivers/platform/x86/amd/Kconfig | 1 +
drivers/platform/x86/amd/dptc.c | 116 +++++++++++++++++++++++++++++--
2 files changed, 113 insertions(+), 4 deletions(-)
diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
index d610092467fc..41ffbd722524 100644
--- a/drivers/platform/x86/amd/Kconfig
+++ b/drivers/platform/x86/amd/Kconfig
@@ -48,6 +48,7 @@ config AMD_ISP_PLATFORM
config AMD_DPTC
tristate "AMD Dynamic Power and Thermal Configuration Interface (DPTCi)"
depends on X86_64 && ACPI && DMI
+ select ACPI_PLATFORM_PROFILE
select FIRMWARE_ATTRIBUTES_CLASS
help
Driver for AMD AGESA ALIB Function 0x0C, the Dynamic Power and
diff --git a/drivers/platform/x86/amd/dptc.c b/drivers/platform/x86/amd/dptc.c
index acfe9cc01bab..1f07e2e6f278 100644
--- a/drivers/platform/x86/amd/dptc.c
+++ b/drivers/platform/x86/amd/dptc.c
@@ -23,6 +23,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
+#include <linux/platform_profile.h>
#include <linux/processor.h>
#include <linux/sysfs.h>
#include <linux/unaligned.h>
@@ -56,8 +57,13 @@ struct dptc_param_limits {
u32 expanded_max;
};
+struct dptc_profile {
+ u32 vals[DPTC_NUM_PARAMS]; /* 0 = don't set / unstage this param */
+};
+
struct dptc_device_limits {
struct dptc_param_limits params[DPTC_NUM_PARAMS];
+ struct dptc_profile profiles[PLATFORM_PROFILE_LAST];
};
struct dptc_param_desc {
@@ -85,6 +91,10 @@ static const struct dptc_device_limits limits_maxhh = { .params = {
[DPTC_PPT_PL2_SPPT] = { 0, 4, 27, 82, 100 },
[DPTC_PPT_PL3_FPPT] = { 0, 4, 40, 85, 100 },
[DPTC_CPU_TEMP] = { 60, 70, 95, 95, 100 },
+}, .profiles = {
+ [PLATFORM_PROFILE_LOW_POWER] = { .vals = { 15, 15, 25, 0 } },
+ [PLATFORM_PROFILE_BALANCED] = { .vals = { 25, 27, 40, 0 } },
+ [PLATFORM_PROFILE_PERFORMANCE] = { .vals = { 60, 63, 85, 0 } },
}};
/* Substring matches against boot_cpu_data.x86_model_id; order matters. */
@@ -134,6 +144,9 @@ struct dptc_priv {
bool expanded;
+ enum platform_profile_option profile;
+ struct device *ppdev;
+
enum dptc_save_mode { SAVE_SINGLE, SAVE_BULK } save_mode;
u32 staged[DPTC_NUM_PARAMS];
@@ -269,6 +282,14 @@ static ssize_t dptc_current_value_show(struct kobject *kobj,
guard(mutex)(&dptc->lock);
+ if (dptc->profile != PLATFORM_PROFILE_CUSTOM) {
+ u32 val = dptc->dev_limits->profiles[dptc->profile].vals[ps->idx];
+
+ if (!val)
+ return sysfs_emit(buf, "\n");
+ return sysfs_emit(buf, "%u\n", val);
+ }
+
if (!dptc->has_staged[ps->idx])
return sysfs_emit(buf, "\n");
return sysfs_emit(buf, "%u\n", dptc->staged[ps->idx]);
@@ -287,6 +308,8 @@ static ssize_t dptc_current_value_store(struct kobject *kobj,
if (count == 1 && buf[0] == '\n') {
guard(mutex)(&dptc->lock);
+ if (dptc->profile != PLATFORM_PROFILE_CUSTOM)
+ return -EPERM;
dptc->has_staged[ps->idx] = false;
return count;
}
@@ -297,6 +320,8 @@ static ssize_t dptc_current_value_store(struct kobject *kobj,
guard(mutex)(&dptc->lock);
+ if (dptc->profile != PLATFORM_PROFILE_CUSTOM)
+ return -EPERM;
min = dptc_get_min(dptc, ps->idx);
max = dptc_get_max(dptc, ps->idx);
if (val < min || (max && val > max))
@@ -426,6 +451,8 @@ static ssize_t dptc_expanded_current_value_store(struct kobject *kobj,
guard(mutex)(&dptc->lock);
+ if (dptc->profile != PLATFORM_PROFILE_CUSTOM)
+ return -EPERM;
dptc->expanded = val;
/* Clear staged values: limits changed, old values may be out of range */
memset(dptc->has_staged, 0, sizeof(dptc->has_staged));
@@ -594,6 +621,78 @@ static void dptc_kset_unregister(void *data)
kset_unregister(data);
}
+/* Platform profile */
+
+static void dptc_apply_profile(struct dptc_priv *dptc,
+ enum platform_profile_option profile)
+{
+ const struct dptc_profile *pp;
+ int i;
+
+ memset(dptc->has_staged, 0, sizeof(dptc->has_staged));
+
+ if (profile == PLATFORM_PROFILE_CUSTOM)
+ return;
+
+ pp = &dptc->dev_limits->profiles[profile];
+ for (i = 0; i < DPTC_NUM_PARAMS; i++) {
+ if (!pp->vals[i])
+ continue;
+ dptc->staged[i] = pp->vals[i];
+ dptc->has_staged[i] = true;
+ }
+}
+
+static int dptc_pp_probe(void *drvdata, unsigned long *choices)
+{
+ struct dptc_priv *dptc = drvdata;
+ int i, j;
+
+ set_bit(PLATFORM_PROFILE_CUSTOM, choices);
+ for (i = 0; i < PLATFORM_PROFILE_LAST; i++) {
+ for (j = 0; j < DPTC_NUM_PARAMS; j++) {
+ if (dptc->dev_limits->profiles[i].vals[j]) {
+ set_bit(i, choices);
+ break;
+ }
+ }
+ }
+ return 0;
+}
+
+static int dptc_pp_get(struct device *dev,
+ enum platform_profile_option *profile)
+{
+ struct dptc_priv *dptc = dev_get_drvdata(dev);
+
+ guard(mutex)(&dptc->lock);
+
+ *profile = dptc->profile;
+ return 0;
+}
+
+static int dptc_pp_set(struct device *dev,
+ enum platform_profile_option profile)
+{
+ struct dptc_priv *dptc = dev_get_drvdata(dev);
+ int ret = 0;
+
+ guard(mutex)(&dptc->lock);
+
+ dptc->profile = profile;
+ dptc_apply_profile(dptc, profile);
+ if (profile != PLATFORM_PROFILE_CUSTOM)
+ ret = dptc_alib_save(dptc);
+
+ return ret;
+}
+
+static const struct platform_profile_ops dptc_pp_ops = {
+ .probe = dptc_pp_probe,
+ .profile_get = dptc_pp_get,
+ .profile_set = dptc_pp_set,
+};
+
static int dptc_resume(struct device *dev)
{
struct dptc_priv *dptc = dev_get_drvdata(dev);
@@ -601,10 +700,14 @@ static int dptc_resume(struct device *dev)
guard(mutex)(&dptc->lock);
- if (dptc->save_mode == SAVE_SINGLE)
+ if (dptc->profile != PLATFORM_PROFILE_CUSTOM) {
+ dptc_apply_profile(dptc, dptc->profile);
ret = dptc_alib_save(dptc);
- else
+ } else if (dptc->save_mode == SAVE_SINGLE) {
+ ret = dptc_alib_save(dptc);
+ } else {
ret = 0;
+ }
if (ret)
dev_warn(dev, "failed to restore settings on resume: %d\n", ret);
@@ -636,8 +739,7 @@ static int dptc_probe(struct platform_device *pdev)
boot_cpu_data.x86_model_id);
dptc->fw_attr_dev = device_create(&firmware_attributes_class,
- NULL, MKDEV(0, 0), NULL,
- DRIVER_NAME);
+ NULL, MKDEV(0, 0), NULL, DRIVER_NAME);
if (IS_ERR(dptc->fw_attr_dev))
return PTR_ERR(dptc->fw_attr_dev);
@@ -680,6 +782,12 @@ static int dptc_probe(struct platform_device *pdev)
if (ret)
return ret;
+ dptc->profile = PLATFORM_PROFILE_CUSTOM;
+ dptc->ppdev = devm_platform_profile_register(dev, "amd-dptc", dptc,
+ &dptc_pp_ops);
+ if (IS_ERR(dptc->ppdev))
+ return PTR_ERR(dptc->ppdev);
+
return 0;
}
--
2.52.0