[RFC 2/2] platform/x86/amd: pmf: Add manual control support

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From: Mario Limonciello <mario.limonciello@xxxxxxx>

A number of users resort to using reverse engineered software like
ryzenadj to manipulate debugging interfaces for modifying APU settings.

At a glance these tools are useful, but the problem is they break
state machines in other software such as the PMF driver or the OEM
EC.

Offer a knob for PMF to allow 'manual control' which will users can
directly change things like fPPT and sPPT. As this can be harmful for
a system to try to push limits outside of a thermal design, taint the
kernel and show a critical message when in use.

Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
 Documentation/ABI/testing/sysfs-amd-pmf | 10 +++
 drivers/platform/x86/amd/pmf/Makefile   |  1 +
 drivers/platform/x86/amd/pmf/core.c     |  9 +++
 drivers/platform/x86/amd/pmf/manual.c   | 88 +++++++++++++++++++++++++
 drivers/platform/x86/amd/pmf/pmf.h      |  5 ++
 drivers/platform/x86/amd/pmf/sps.c      |  4 ++
 6 files changed, 117 insertions(+)
 create mode 100644 drivers/platform/x86/amd/pmf/manual.c

diff --git a/Documentation/ABI/testing/sysfs-amd-pmf b/Documentation/ABI/testing/sysfs-amd-pmf
index 7fc0e1c2b76b..6f3d5cbf443f 100644
--- a/Documentation/ABI/testing/sysfs-amd-pmf
+++ b/Documentation/ABI/testing/sysfs-amd-pmf
@@ -11,3 +11,13 @@ Description:	Reading this file tells if the AMD Platform Management(PMF)
 		To turn off CnQF user can write "off" to the sysfs node.
 		Note: Systems that support auto mode will not have this sysfs file
 		available.
+
+What:		/sys/devices/platform/*/{spl, fppt, sppt, sppt_apu_only, stt_min, stt_limit_apu, stt_skip_temp}
+Date:		December 2024
+Contact:	Mario Limonciello <mario.limonciello@xxxxxxx>
+Description:	Manual control of AMD PMF APU coefficients
+		.
+		These files are used to manually control the APU coefficients.
+		In order to write to these files the module most be
+		loaded with manual_control=1 and the user must write "custom"
+		to the ACPI platform profile.
diff --git a/drivers/platform/x86/amd/pmf/Makefile b/drivers/platform/x86/amd/pmf/Makefile
index 7d6079b02589..81444d6f4428 100644
--- a/drivers/platform/x86/amd/pmf/Makefile
+++ b/drivers/platform/x86/amd/pmf/Makefile
@@ -7,4 +7,5 @@
 obj-$(CONFIG_AMD_PMF) += amd-pmf.o
 amd-pmf-objs := core.o acpi.o sps.o \
 		auto-mode.o cnqf.o \
+		manual.o \
 		tee-if.o spc.o pmf-quirks.o
diff --git a/drivers/platform/x86/amd/pmf/core.c b/drivers/platform/x86/amd/pmf/core.c
index d6af0ca036f1..52a68ca094be 100644
--- a/drivers/platform/x86/amd/pmf/core.c
+++ b/drivers/platform/x86/amd/pmf/core.c
@@ -53,6 +53,10 @@ static bool force_load;
 module_param(force_load, bool, 0444);
 MODULE_PARM_DESC(force_load, "Force load this driver on supported older platforms (experimental)");
 
+bool pmf_manual_control;
+module_param_named(manual_control, pmf_manual_control, bool, 0444);
+MODULE_PARM_DESC(manual_control, "Expose manual control knobs (experimental)");
+
 static int amd_pmf_pwr_src_notify_call(struct notifier_block *nb, unsigned long event, void *data)
 {
 	struct amd_pmf_dev *pmf = container_of(nb, struct amd_pmf_dev, pwr_src_notifier);
@@ -349,6 +353,10 @@ static void amd_pmf_init_features(struct amd_pmf_dev *dev)
 		dev_dbg(dev->dev, "SPS enabled and Platform Profiles registered\n");
 	}
 
+	if (pmf_manual_control) {
+		amd_pmf_init_manual_control(dev);
+		return;
+	}
 	amd_pmf_init_smart_pc(dev);
 	if (dev->smart_pc_enabled) {
 		dev_dbg(dev->dev, "Smart PC Solution Enabled\n");
@@ -485,6 +493,7 @@ static void amd_pmf_remove(struct platform_device *pdev)
 
 static const struct attribute_group *amd_pmf_driver_groups[] = {
 	&cnqf_feature_attribute_group,
+	&manual_attribute_group,
 	NULL,
 };
 
diff --git a/drivers/platform/x86/amd/pmf/manual.c b/drivers/platform/x86/amd/pmf/manual.c
new file mode 100644
index 000000000000..b33fc3cd8d61
--- /dev/null
+++ b/drivers/platform/x86/amd/pmf/manual.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AMD Platform Management Framework Driver
+ *
+ * Copyright (c) 2024, Advanced Micro Devices, Inc.
+ * All Rights Reserved.
+ *
+ * Author: Mario Limonciello <mario.limonciello@xxxxxxx>
+ */
+
+#include "pmf.h"
+
+#define pmf_manual_attribute(_name, _set_command, _get_command)		\
+static ssize_t _name##_store(struct device *d,				\
+			     struct device_attribute *attr,		\
+			     const char *buf, size_t count)		\
+{									\
+	struct amd_pmf_dev *dev = dev_get_drvdata(d);			\
+	uint val;							\
+									\
+	if (dev->current_profile != PLATFORM_PROFILE_CUSTOM) {		\
+		dev_warn_once(dev->dev,					\
+			      "Manual control is disabled, please set "	\
+			      "platform profile to custom.\n");		\
+		return -EINVAL;						\
+	}								\
+									\
+	if (kstrtouint(buf, 10, &val) < 0)				\
+		return -EINVAL;						\
+									\
+	amd_pmf_send_cmd(dev, _set_command, false, val, NULL);		\
+									\
+	return count;							\
+}									\
+static ssize_t _name##_show(struct device *d,				\
+			   struct device_attribute *attr,		\
+			   char *buf)					\
+{									\
+	struct amd_pmf_dev *dev = dev_get_drvdata(d);			\
+	uint val;							\
+									\
+	amd_pmf_send_cmd(dev, _get_command, true, ARG_NONE, &val);	\
+									\
+	return sysfs_emit(buf, "%u\n", val);				\
+}
+
+pmf_manual_attribute(spl, SET_SPL, GET_SPL);
+static DEVICE_ATTR_RW(spl);
+pmf_manual_attribute(fppt, SET_FPPT, GET_FPPT);
+static DEVICE_ATTR_RW(fppt);
+pmf_manual_attribute(sppt, SET_SPPT, GET_SPPT);
+static DEVICE_ATTR_RW(sppt);
+pmf_manual_attribute(sppt_apu_only, SET_SPPT_APU_ONLY, GET_SPPT_APU_ONLY);
+static DEVICE_ATTR_RW(sppt_apu_only);
+pmf_manual_attribute(stt_min, SET_STT_MIN_LIMIT, GET_STT_MIN_LIMIT);
+static DEVICE_ATTR_RW(stt_min);
+pmf_manual_attribute(stt_limit_apu, SET_STT_LIMIT_APU, GET_STT_LIMIT_APU);
+static DEVICE_ATTR_RW(stt_limit_apu);
+pmf_manual_attribute(stt_skin_temp, SET_STT_LIMIT_HS2, GET_STT_LIMIT_HS2);
+static DEVICE_ATTR_RW(stt_skin_temp);
+
+static umode_t manual_attr_is_visible(struct kobject *kobj, struct attribute *attr, int idx)
+{
+	return pmf_manual_control ? 0660 : 0;
+}
+
+static struct attribute *manual_attrs[] = {
+	&dev_attr_spl.attr,
+	&dev_attr_fppt.attr,
+	&dev_attr_sppt.attr,
+	&dev_attr_sppt_apu_only.attr,
+	&dev_attr_stt_min.attr,
+	&dev_attr_stt_limit_apu.attr,
+	&dev_attr_stt_skin_temp.attr,
+	NULL,
+};
+
+const struct attribute_group manual_attribute_group = {
+	.attrs = manual_attrs,
+	.is_visible = manual_attr_is_visible,
+};
+
+void amd_pmf_init_manual_control(struct amd_pmf_dev *dev)
+{
+	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+	pr_crit("Manual PMF control is enabled, please disable it before "
+		"reporting any bugs unrelated to PMF.\n");
+}
diff --git a/drivers/platform/x86/amd/pmf/pmf.h b/drivers/platform/x86/amd/pmf/pmf.h
index 8ce8816da9c1..ca3df63cf190 100644
--- a/drivers/platform/x86/amd/pmf/pmf.h
+++ b/drivers/platform/x86/amd/pmf/pmf.h
@@ -798,4 +798,9 @@ void amd_pmf_dump_ta_inputs(struct amd_pmf_dev *dev, struct ta_pmf_enact_table *
 /* Quirk infrastructure */
 void amd_pmf_quirks_init(struct amd_pmf_dev *dev);
 
+/* Manual configuration */
+extern bool pmf_manual_control;
+extern const struct attribute_group manual_attribute_group;
+void amd_pmf_init_manual_control(struct amd_pmf_dev *dev);
+
 #endif /* PMF_H */
diff --git a/drivers/platform/x86/amd/pmf/sps.c b/drivers/platform/x86/amd/pmf/sps.c
index 92f7fb22277d..6db88e523a86 100644
--- a/drivers/platform/x86/amd/pmf/sps.c
+++ b/drivers/platform/x86/amd/pmf/sps.c
@@ -305,6 +305,8 @@ int amd_pmf_get_pprof_modes(struct amd_pmf_dev *pmf)
 	case PLATFORM_PROFILE_LOW_POWER:
 		mode = POWER_MODE_POWER_SAVER;
 		break;
+	case PLATFORM_PROFILE_CUSTOM:
+		return 0;
 	default:
 		dev_err(pmf->dev, "Unknown Platform Profile.\n");
 		return -EOPNOTSUPP;
@@ -412,6 +414,8 @@ int amd_pmf_init_sps(struct amd_pmf_dev *dev)
 	set_bit(PLATFORM_PROFILE_LOW_POWER, dev->pprof.choices);
 	set_bit(PLATFORM_PROFILE_BALANCED, dev->pprof.choices);
 	set_bit(PLATFORM_PROFILE_PERFORMANCE, dev->pprof.choices);
+	if (pmf_manual_control)
+		set_bit(PLATFORM_PROFILE_CUSTOM, dev->pprof.choices);
 
 	/* Create platform_profile structure and register */
 	err = platform_profile_register(&dev->pprof);
-- 
2.43.0





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