Re: [RFC v3 2/4] platform/x86/amd: dptc: Add AMD DPTCi driver
From: Antheas Kapenekakis
Date: Sat Mar 07 2026 - 18:02:48 EST
On Sat, 7 Mar 2026 at 22:56, Rong Zhang <i@xxxxxxxx> wrote:
>
> Hi Antheas,
>
> Thanks for working on it.
>
> I think this driver is useful for me and I will see if I can test it on
> my devices once I find some time. They're not handhelds but I am sure
> at least one of them has the ALIB method. It'd better if a module
> option can be used to bypass the quirk table so that testing against a
> new device will be easier. Such an option should taint the kernel ofc.
I will defer to Mario for this one. Previous iterations of this series
had an override. Before I posted V2 I had a module param that allowed
matching by ident.
> That being said, I have some review comments. Please see below and my
> following replies.
>
> On Sat, 2026-03-07 at 12:55 +0100, Antheas Kapenekakis wrote:
> > Add a driver for AMD AGESA ALIB Function 0x0C, the Dynamic Power and
> > Thermal Configuration interface (DPTCi). This exposes TDP and thermal
> > parameters for AMD APU-based handheld devices via the
> > firmware-attributes sysfs ABI.
> >
> > Parameters are staged and atomically committed through ALIB. The driver
> > supports two save modes: "single" (apply immediately on write) and
> > "bulk" (stage values, then commit with "save"). An "expanded_limits"
> > toggle widens the allowed parameter ranges beyond device defaults.
> >
> > Initial device support: GPD Win 5 (AMD Ryzen AI MAX).
> >
> > Assisted-by: Claude:claude-opus-4-6
> > Signed-off-by: Antheas Kapenekakis <lkml@xxxxxxxxxxx>
> > ---
> > MAINTAINERS | 6 +
> > drivers/platform/x86/amd/Kconfig | 14 +
> > drivers/platform/x86/amd/Makefile | 2 +
> > drivers/platform/x86/amd/dptc.c | 747 ++++++++++++++++++++++++++++++
> > 4 files changed, 769 insertions(+)
> > create mode 100644 drivers/platform/x86/amd/dptc.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index e08767323763..915293594641 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -1096,6 +1096,12 @@ S: Supported
> > F: drivers/gpu/drm/amd/display/dc/dml/
> > F: drivers/gpu/drm/amd/display/dc/dml2_0/
> >
> > +AMD DPTC DRIVER
> > +M: Antheas Kapenekakis <lkml@xxxxxxxxxxx>
> > +L: platform-driver-x86@xxxxxxxxxxxxxxx
> > +S: Maintained
> > +F: drivers/platform/x86/amd/dptc.c
> > +
> > AMD FAM15H PROCESSOR POWER MONITORING DRIVER
> > M: Huang Rui <ray.huang@xxxxxxx>
> > L: linux-hwmon@xxxxxxxxxxxxxxx
> > diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
> > index b813f9265368..d610092467fc 100644
> > --- a/drivers/platform/x86/amd/Kconfig
> > +++ b/drivers/platform/x86/amd/Kconfig
> > @@ -44,3 +44,17 @@ config AMD_ISP_PLATFORM
> >
> > This driver can also be built as a module. If so, the module
> > will be called amd_isp4.
> > +
> > +config AMD_DPTC
> > + tristate "AMD Dynamic Power and Thermal Configuration Interface (DPTCi)"
> > + depends on X86_64 && ACPI && DMI
> > + select FIRMWARE_ATTRIBUTES_CLASS
> > + help
> > + Driver for AMD AGESA ALIB Function 0x0C, the Dynamic Power and
> > + Thermal Configuration Interface (DPTCi). Exposes TDP and thermal
> > + parameters for AMD APU-based handheld devices via the
> > + firmware-attributes sysfs ABI, allowing userspace tools to stage
> > + and atomically commit power limit settings. Requires a DMI match
> > + for the device and a recognized AMD SoC.
> > +
> > + If built as a module, the module will be called amd_dptc.
> > diff --git a/drivers/platform/x86/amd/Makefile b/drivers/platform/x86/amd/Makefile
> > index f6ff0c837f34..862a609bfe38 100644
> > --- a/drivers/platform/x86/amd/Makefile
> > +++ b/drivers/platform/x86/amd/Makefile
> > @@ -12,3 +12,5 @@ obj-$(CONFIG_AMD_PMF) += pmf/
> > obj-$(CONFIG_AMD_WBRF) += wbrf.o
> > obj-$(CONFIG_AMD_ISP_PLATFORM) += amd_isp4.o
> > obj-$(CONFIG_AMD_HFI) += hfi/
> > +obj-$(CONFIG_AMD_DPTC) += amd_dptc.o
> > +amd_dptc-y := dptc.o
> > diff --git a/drivers/platform/x86/amd/dptc.c b/drivers/platform/x86/amd/dptc.c
> > new file mode 100644
> > index 000000000000..acfe9cc01bab
> > --- /dev/null
> > +++ b/drivers/platform/x86/amd/dptc.c
> > @@ -0,0 +1,747 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * AMD Dynamic Power and Thermal Configuration Interface (DPTCi) driver
> > + *
> > + * Exposes AMD APU power and thermal parameters via the firmware-attributes
> > + * sysfs ABI. Parameters are staged and atomically committed through the
> > + * AGESA ALIB Function 0x0C (Dynamic Power and Thermal Configuration
> > + * interface).
> > + *
> > + * Reference: AMD AGESA Publication #44065, Appendix E.5
> > + * https://docs.amd.com/v/u/en-US/44065_Arch2008
> > + *
> > + * Copyright (C) 2026 Antheas Kapenekakis <lkml@xxxxxxxxxxx>
> > + */
> > +
> > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > +
> > +#include <linux/acpi.h>
> > +#include <linux/cleanup.h>
> > +#include <linux/dmi.h>
> > +#include <linux/init.h>
> > +#include <linux/kobject.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/processor.h>
> > +#include <linux/sysfs.h>
> > +#include <linux/unaligned.h>
> > +
> > +#include "../firmware_attributes_class.h"
> > +
> > +#define DRIVER_NAME "amd-dptc"
> > +
> > +#define ALIB_FUNC_DPTC 0x0C
> > +#define ALIB_PATH "\\_SB.ALIB"
> > +
> > +#define ALIB_ID_TEMP_TARGET 0x03
> > +#define ALIB_ID_STAPM_LIMIT 0x05
> > +#define ALIB_ID_FAST_LIMIT 0x06
> > +#define ALIB_ID_SLOW_LIMIT 0x07
> > +#define ALIB_ID_SKIN_LIMIT 0x2E
> > +
> > +enum dptc_param_idx {
> > + DPTC_PPT_PL1_SPL, /* STAPM + skin limit (set together) */
> > + DPTC_PPT_PL2_SPPT, /* slow PPT limit */
> > + DPTC_PPT_PL3_FPPT, /* fast PPT limit */
> > + DPTC_CPU_TEMP, /* thermal control target */
> > + DPTC_NUM_PARAMS,
> > +};
> > +
> > +struct dptc_param_limits {
> > + u32 expanded_min;
> > + u32 device_min;
> > + u32 def;
> > + u32 device_max;
> > + u32 expanded_max;
> > +};
> > +
> > +struct dptc_device_limits {
> > + struct dptc_param_limits params[DPTC_NUM_PARAMS];
> > +};
> > +
> > +struct dptc_param_desc {
> > + const char *name;
> > + const char *display_name;
> > + u16 scale; /* sysfs-to-ALIB multiplier (e.g. 1000 for W->mW) */
> > + u8 param_id;
> > + u8 param_id2; /* secondary ALIB ID, 0 if none */
> > +};
> > +
> > +static const struct dptc_param_desc dptc_params[DPTC_NUM_PARAMS] = {
> > + [DPTC_PPT_PL1_SPL] = { "ppt_pl1_spl", "Sustained power limit (W)",
> > + 1000, ALIB_ID_STAPM_LIMIT, ALIB_ID_SKIN_LIMIT },
> > + [DPTC_PPT_PL2_SPPT] = { "ppt_pl2_sppt", "Slow PPT limit (W)",
> > + 1000, ALIB_ID_SLOW_LIMIT },
> > + [DPTC_PPT_PL3_FPPT] = { "ppt_pl3_fppt", "Fast PPT limit (W)",
> > + 1000, ALIB_ID_FAST_LIMIT },
> > + [DPTC_CPU_TEMP] = { "cpu_temp", "Thermal control limit (C)",
> > + 1, ALIB_ID_TEMP_TARGET },
> > +};
>
> The indent here just made me crazy :-/
>
> Align the contents after line breaks to the left braces.
I will review how to do the alignment, although I'm not happy with how
aligning to spaces will look. PL1 will overflow.
> > +
> > +/* AI MAX Handheld class: GPD Win 5 */
> > +static const struct dptc_device_limits limits_maxhh = { .params = {
>
> Please don't save a line by zipping braces like this. It's hard to read
> and likely to be missed when glancing the code (that's what happened to
> me and it really confused me).
>
> I found you did the same in [PATCH v3 3/4] for `.profiles'. That should
> be avoided too.
This is a leftover from before adding profiles. I guess it does not
make much sense now. I can reflow.
> > + [DPTC_PPT_PL1_SPL] = { 0, 4, 25, 80, 100 },
> > + [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 },
> > +}};
> > +
> > +/* Substring matches against boot_cpu_data.x86_model_id; order matters. */
> > +static const char * const dptc_soc_table[] = {
> > + /* AI MAX */
> > + "AMD RYZEN AI MAX+ 395",
> > + "AMD RYZEN AI MAX+ 385",
> > + "AMD RYZEN AI MAX 380",
> > + NULL,
> > +};
> > +
> > +static const struct dmi_system_id dptc_dmi_table[] = {
> > + /* GPD */
> > + {
> > + .ident = "GPD Win 5",
> > + .matches = {
> > + DMI_MATCH(DMI_SYS_VENDOR, "GPD"),
> > + DMI_MATCH(DMI_PRODUCT_NAME, "G1618-05"),
> > + },
> > + .driver_data = (void *)&limits_maxhh,
> > + },
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(dmi, dptc_dmi_table);
> > +
> > +struct dptc_priv;
> > +
> > +struct dptc_attr_sysfs {
> > + struct dptc_priv *priv;
> > + struct kobj_attribute current_value;
> > + struct kobj_attribute default_value;
> > + struct kobj_attribute min_value;
> > + struct kobj_attribute max_value;
> > + struct kobj_attribute scalar_increment;
> > + struct kobj_attribute display_name;
> > + struct kobj_attribute type;
> > + struct attribute *attrs[8];
> > + struct attribute_group group;
> > + int idx;
> > +};
> > +
> > +struct dptc_priv {
> > + struct device *fw_attr_dev;
> > + struct kset *fw_attr_kset;
> > +
> > + const struct dptc_device_limits *dev_limits;
> > +
> > + bool expanded;
> > +
> > + enum dptc_save_mode { SAVE_SINGLE, SAVE_BULK } save_mode;
>
> Defining the enumeration separately will improve readability.
>
> > +
> > + u32 staged[DPTC_NUM_PARAMS];
> > + bool has_staged[DPTC_NUM_PARAMS];
> > +
> > + /* Protects mutable driver state */
>
> The comment is nonsense. To make it helpful, it should be "Protects
> members above/below" with properly arranged structure layout.
>
> > + struct mutex lock;
> > +
> > + struct dptc_attr_sysfs params[DPTC_NUM_PARAMS];
> > + struct dptc_attr_sysfs expanded_attr;
> > + struct kobj_attribute save_settings_attr;
> > +};
> > +
> > +static struct platform_device *dptc_pdev;
> > +
> > +static u32 dptc_get_min(struct dptc_priv *dptc, int idx)
> > +{
> > + return dptc->expanded ? dptc->dev_limits->params[idx].expanded_min
> > + : dptc->dev_limits->params[idx].device_min;
> > +}
> > +
> > +static u32 dptc_get_max(struct dptc_priv *dptc, int idx)
> > +{
> > + return dptc->expanded ? dptc->dev_limits->params[idx].expanded_max
> > + : dptc->dev_limits->params[idx].device_max;
> > +}
> > +
> > +static u32 dptc_get_default(struct dptc_priv *dptc, int idx)
> > +{
> > + return dptc->dev_limits->params[idx].def;
> > +}
> > +
> > +static int dptc_alib_call(const u8 *ids, const u32 *vals, int count)
> > +{
> > + union acpi_object in_params[2];
> > + struct acpi_object_list input;
> > + acpi_status status;
> > + u32 buf_size;
> > + int i, off;
> > + u8 *buf;
> > +
> > + if (count == 0)
> > + return -EINVAL;
>
> Return -ENOENT as think-lmi does (see its save_settings_store()) and
> update the documentation accordingly.
>
> > +
> > + /* Buffer layout: WORD total_size + count * (BYTE id + DWORD value) */
> > + buf_size = 2 + count * 5;
> > + buf = kzalloc(buf_size, GFP_KERNEL);
> > + if (!buf)
> > + return -ENOMEM;
> > +
> > + put_unaligned_le16(buf_size, buf);
> > +
> > + for (i = 0; i < count; i++) {
> > + off = 2 + i * 5;
> > + buf[off] = ids[i];
> > + put_unaligned_le32(vals[i], buf + off + 1);
>
> put_unaligned_le32(vals[i], &buf[off + 1]);
>
> > + }
> > +
> > + in_params[0].type = ACPI_TYPE_INTEGER;
> > + in_params[0].integer.value = ALIB_FUNC_DPTC;
> > + in_params[1].type = ACPI_TYPE_BUFFER;
> > + in_params[1].buffer.length = buf_size;
> > + in_params[1].buffer.pointer = buf;
>
> Misaligned `='.
>
> > +
> > + input.count = 2;
> > + input.pointer = in_params;
> > +
> > + status = acpi_evaluate_object(NULL, ALIB_PATH, &input, NULL);
> > + kfree(buf);
> > +
> > + if (ACPI_FAILURE(status)) {
> > + pr_err("ALIB call failed: %s\n",
> > + acpi_format_exception(status));
> > + return -EIO;
> > + }
> > +
> > + pr_debug("sent %d ALIB parameter(s)\n", count);
> > + return 0;
> > +}
> > +
> > +static int dptc_alib_send_one(int idx, u32 val)
> > +{
> > + u32 hw_val = val * dptc_params[idx].scale;
> > + u32 vals[2];
> > + u8 ids[2];
> > + int count = 0;
> > +
> > + ids[count] = dptc_params[idx].param_id;
> > + vals[count] = hw_val;
> > + count++;
> > + if (dptc_params[idx].param_id2) {
> > + ids[count] = dptc_params[idx].param_id2;
> > + vals[count] = hw_val;
> > + count++;
> > + }
> > +
> > + return dptc_alib_call(ids, vals, count);
> > +}
> > +
> > +static int dptc_alib_save(struct dptc_priv *dptc)
> > +{
> > + u32 vals[DPTC_NUM_PARAMS * 2];
> > + u8 ids[DPTC_NUM_PARAMS * 2];
> > + int i, count = 0;
> > + u32 hw_val;
> > +
> > + for (i = 0; i < DPTC_NUM_PARAMS; i++) {
> > + if (!dptc->has_staged[i])
> > + continue;
> > +
> > + hw_val = dptc->staged[i] * dptc_params[i].scale;
> > + ids[count] = dptc_params[i].param_id;
> > + vals[count] = hw_val;
> > + count++;
> > + if (dptc_params[i].param_id2) {
> > + ids[count] = dptc_params[i].param_id2;
> > + vals[count] = hw_val;
> > + count++;
> > + }
>
> I could imagine a helper function to prevent replicating the same code
> patterns twice:
>
> static size_t dptc_alib_fill_param(u8 *ids, u32 *vals, size_t offset,
> enum dptc_param_idx param, u32 val)
> {
> u32 hw_val = val * dptc_params[param].scale;
>
> ids[offset] = dptc_params[param].param_id;
> vals[offset++] = hw_val;
>
> if (dptc_params[param].param_id2) {
> ids[offset] = dptc_params[param].param_id2;
> vals[offset++] = hw_val;
> }
>
> return offset;
> }
>
> > + }
> > +
> > + return dptc_alib_call(ids, vals, count);
> > +}
> > +
> > +/* Sysfs callbacks */
> > +
> > +static ssize_t dptc_current_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, current_value);
> > + struct dptc_priv *dptc = ps->priv;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + if (!dptc->has_staged[ps->idx])
> > + return sysfs_emit(buf, "\n");
> > + return sysfs_emit(buf, "%u\n", dptc->staged[ps->idx]);
> > +}
> > +
> > +static ssize_t dptc_current_value_store(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, current_value);
> > + struct dptc_priv *dptc = ps->priv;
> > + u32 val, min, max;
> > + int ret;
> > +
> > + if (count == 1 && buf[0] == '\n') {
> > + guard(mutex)(&dptc->lock);
> > +
> > + dptc->has_staged[ps->idx] = false;
> > + return count;
> > + }
> > +
> > + ret = kstrtou32(buf, 10, &val);
> > + if (ret)
> > + return ret;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + min = dptc_get_min(dptc, ps->idx);
> > + max = dptc_get_max(dptc, ps->idx);
> > + if (val < min || (max && val > max))
> > + return -EINVAL;
> > + dptc->staged[ps->idx] = val;
> > + dptc->has_staged[ps->idx] = true;
> > + if (dptc->save_mode == SAVE_SINGLE)
> > + ret = dptc_alib_send_one(ps->idx, val);
> > +
> > + return ret ? ret : count;
> > +}
> > +
> > +static ssize_t dptc_default_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, default_value);
> > +
> > + return sysfs_emit(buf, "%u\n", dptc_get_default(ps->priv, ps->idx));
> > +}
> > +
> > +static ssize_t dptc_min_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, min_value);
> > + struct dptc_priv *dptc = ps->priv;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + return sysfs_emit(buf, "%u\n", dptc_get_min(dptc, ps->idx));
> > +}
> > +
> > +static ssize_t dptc_max_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, max_value);
> > + struct dptc_priv *dptc = ps->priv;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + return sysfs_emit(buf, "%u\n", dptc_get_max(dptc, ps->idx));
> > +}
> > +
> > +static ssize_t dptc_scalar_increment_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + return sysfs_emit(buf, "1\n");
> > +}
> > +
> > +static ssize_t dptc_display_name_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, display_name);
> > + return sysfs_emit(buf, "%s\n", dptc_params[ps->idx].display_name);
> > +}
> > +
> > +static ssize_t dptc_type_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + return sysfs_emit(buf, "integer\n");
> > +}
> > +
> > +static ssize_t dptc_save_settings_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + struct dptc_priv *dptc =
> > + container_of(attr, struct dptc_priv, save_settings_attr);
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + if (dptc->save_mode == SAVE_SINGLE)
> > + return sysfs_emit(buf, "single\n");
> > + return sysfs_emit(buf, "bulk\n");
> > +}
> > +
> > +static ssize_t dptc_save_settings_store(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct dptc_priv *dptc =
> > + container_of(attr, struct dptc_priv, save_settings_attr);
> > + int ret = 0;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + if (sysfs_streq(buf, "save"))
>
> Please don't rely on the `count == 0' check in dptc_alib_call(). `dptc-
> >save_mode == SAVE_SINGLE' should result in -EOPNOTSUPP to maintain
> consistency with think-lmi (update the documentation accordingly).
I will consider it. But this is subtractive behavior. We are still ABI
compliant even if the write goes through and it does not affect
functionality.
> > + ret = dptc_alib_save(dptc);
> > + else if (sysfs_streq(buf, "single"))
> > + dptc->save_mode = SAVE_SINGLE;
> > + else if (sysfs_streq(buf, "bulk"))
> > + dptc->save_mode = SAVE_BULK;
> > + else
> > + return -EINVAL;
> > +
> > + return ret ? ret : count;
> > +}
> > +
> > +static ssize_t dptc_expanded_current_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, current_value);
> > + struct dptc_priv *dptc = ps->priv;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + return sysfs_emit(buf, "%d\n", dptc->expanded);
> > +}
> > +
> > +static ssize_t dptc_expanded_current_value_store(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct dptc_attr_sysfs *ps =
> > + container_of(attr, struct dptc_attr_sysfs, current_value);
> > + struct dptc_priv *dptc = ps->priv;
> > + bool val;
> > + int ret;
> > +
> > + ret = kstrtobool(buf, &val);
> > + if (ret)
> > + return ret;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + dptc->expanded = val;
> > + /* Clear staged values: limits changed, old values may be out of range */
> > + memset(dptc->has_staged, 0, sizeof(dptc->has_staged));
>
> I'd prefer using a bitmap so that you don't need to use memset() to
> clear them. It also saves some memory if more parameters are added in
> the future.
I will review if has_staged needs to exist. Values cannot be 0 anyway.
A bit map has other readability issues.
> > +
> > + return count;
> > +}
> > +
> > +static ssize_t dptc_expanded_default_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + return sysfs_emit(buf, "0\n");
> > +}
> > +
> > +static ssize_t dptc_expanded_min_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + return sysfs_emit(buf, "0\n");
> > +}
> > +
> > +static ssize_t dptc_expanded_max_value_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + return sysfs_emit(buf, "1\n");
> > +}
> > +
> > +static ssize_t dptc_expanded_scalar_increment_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + return sysfs_emit(buf, "1\n");
> > +}
> > +
> > +static ssize_t dptc_expanded_display_name_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + return sysfs_emit(buf, "Expanded Limits\n");
> > +}
> > +
> > +static ssize_t dptc_expanded_type_show(struct kobject *kobj,
> > + struct kobj_attribute *attr, char *buf)
> > +{
> > + return sysfs_emit(buf, "integer\n");
> > +}
> > +
> > +/* Sysfs setup */
> > +
> > +static void dptc_setup_param_sysfs(struct dptc_priv *dptc,
> > + struct dptc_attr_sysfs *ps, int idx)
> > +{
> > + ps->priv = dptc;
> > + ps->idx = idx;
> > +
> > + sysfs_attr_init(&ps->current_value.attr);
> > + ps->current_value.attr.name = "current_value";
> > + ps->current_value.attr.mode = 0644;
> > + ps->current_value.show = dptc_current_value_show;
> > + ps->current_value.store = dptc_current_value_store;
> > +
> > + sysfs_attr_init(&ps->default_value.attr);
> > + ps->default_value.attr.name = "default_value";
> > + ps->default_value.attr.mode = 0444;
> > + ps->default_value.show = dptc_default_value_show;
> > +
> > + sysfs_attr_init(&ps->min_value.attr);
> > + ps->min_value.attr.name = "min_value";
> > + ps->min_value.attr.mode = 0444;
> > + ps->min_value.show = dptc_min_value_show;
> > +
> > + sysfs_attr_init(&ps->max_value.attr);
> > + ps->max_value.attr.name = "max_value";
> > + ps->max_value.attr.mode = 0444;
> > + ps->max_value.show = dptc_max_value_show;
> > +
> > + sysfs_attr_init(&ps->scalar_increment.attr);
> > + ps->scalar_increment.attr.name = "scalar_increment";
> > + ps->scalar_increment.attr.mode = 0444;
> > + ps->scalar_increment.show = dptc_scalar_increment_show;
> > +
> > + sysfs_attr_init(&ps->display_name.attr);
> > + ps->display_name.attr.name = "display_name";
> > + ps->display_name.attr.mode = 0444;
> > + ps->display_name.show = dptc_display_name_show;
> > +
> > + sysfs_attr_init(&ps->type.attr);
> > + ps->type.attr.name = "type";
> > + ps->type.attr.mode = 0444;
> > + ps->type.show = dptc_type_show;
> > +
> > + ps->attrs[0] = &ps->current_value.attr;
> > + ps->attrs[1] = &ps->default_value.attr;
> > + ps->attrs[2] = &ps->min_value.attr;
> > + ps->attrs[3] = &ps->max_value.attr;
> > + ps->attrs[4] = &ps->scalar_increment.attr;
> > + ps->attrs[5] = &ps->display_name.attr;
> > + ps->attrs[6] = &ps->type.attr;
> > + ps->attrs[7] = NULL;
> > +
> > + ps->group.name = dptc_params[idx].name;
> > + ps->group.attrs = ps->attrs;
> > +}
> > +
> > +static void dptc_setup_expanded_sysfs(struct dptc_priv *dptc,
> > + struct dptc_attr_sysfs *ps)
> > +{
> > + ps->priv = dptc;
> > + sysfs_attr_init(&ps->current_value.attr);
> > + ps->current_value.attr.name = "current_value";
> > + ps->current_value.attr.mode = 0644;
> > + ps->current_value.show = dptc_expanded_current_value_show;
> > + ps->current_value.store = dptc_expanded_current_value_store;
> > +
> > + sysfs_attr_init(&ps->default_value.attr);
> > + ps->default_value.attr.name = "default_value";
> > + ps->default_value.attr.mode = 0444;
> > + ps->default_value.show = dptc_expanded_default_value_show;
> > +
> > + sysfs_attr_init(&ps->min_value.attr);
> > + ps->min_value.attr.name = "min_value";
> > + ps->min_value.attr.mode = 0444;
> > + ps->min_value.show = dptc_expanded_min_value_show;
> > +
> > + sysfs_attr_init(&ps->max_value.attr);
> > + ps->max_value.attr.name = "max_value";
> > + ps->max_value.attr.mode = 0444;
> > + ps->max_value.show = dptc_expanded_max_value_show;
> > +
> > + sysfs_attr_init(&ps->scalar_increment.attr);
> > + ps->scalar_increment.attr.name = "scalar_increment";
> > + ps->scalar_increment.attr.mode = 0444;
> > + ps->scalar_increment.show = dptc_expanded_scalar_increment_show;
> > +
> > + sysfs_attr_init(&ps->display_name.attr);
> > + ps->display_name.attr.name = "display_name";
> > + ps->display_name.attr.mode = 0444;
> > + ps->display_name.show = dptc_expanded_display_name_show;
> > +
> > + sysfs_attr_init(&ps->type.attr);
> > + ps->type.attr.name = "type";
> > + ps->type.attr.mode = 0444;
> > + ps->type.show = dptc_expanded_type_show;
> > +
> > + ps->attrs[0] = &ps->current_value.attr;
> > + ps->attrs[1] = &ps->default_value.attr;
> > + ps->attrs[2] = &ps->min_value.attr;
> > + ps->attrs[3] = &ps->max_value.attr;
> > + ps->attrs[4] = &ps->scalar_increment.attr;
> > + ps->attrs[5] = &ps->display_name.attr;
> > + ps->attrs[6] = &ps->type.attr;
> > + ps->attrs[7] = NULL;
> > +
> > + ps->group.name = "expanded_limits";
> > + ps->group.attrs = ps->attrs;
> > +}
>
> As Derek has said in v2, use macros to rearrange them.
>
> It's painful to read all these things as I'll need to scroll the screen
> quite a lot just to read something with a low information density.
> That's why there are numerous macros defined in include/linux/sysfs.h.
> I could imagine defining macros like DPTC{,_EXPANDED}_ATTR_{RO,RW}.
This driver consists of two instantiation blocks. It is not possible
to dedup the initialization functions and save space because the
function holders and structs that would be needed undo that.
The blocks in lenovo other are significantly less readable and harder
to write. Perhaps you save around 20 lines. But it is not worth it
imo.
> Meanwhile, I am not very sure why you would have to dynamically
> initialize all these attributes. I haven't notice a blocker of defining
> them statically at the module-level (see how lenovo-wmi-other did). Am
> I missing anything?
You are not missing something. There is no benefit to dynamic
allocation. Static allocation needs macros.
> > +
> > +static void dptc_fw_dev_unregister(void *data)
> > +{
> > + device_unregister(data);
> > +}
> > +
> > +static void dptc_kset_unregister(void *data)
> > +{
> > + kset_unregister(data);
> > +}
> > +
> > +static int dptc_resume(struct device *dev)
> > +{
> > + struct dptc_priv *dptc = dev_get_drvdata(dev);
> > + int ret;
> > +
> > + guard(mutex)(&dptc->lock);
> > +
> > + if (dptc->save_mode == SAVE_SINGLE)
> > + ret = dptc_alib_save(dptc);
>
> I don't see why bulk mode and single mode should have divergence on
> resuming behavior.
This is personal preference. I'd rather bulk mode completely disengage
the driver handling. It also gives it a better reason to exist. After
all, ALIB runs a for loop inside it, there is no difference calling it
3 times or 1 as far as the GPU is concerned. It is only ACPI overhead.
The original name was commit_mode, with manual/auto. But while working
on the ABI entry I found save_settings, and it was an ABI match so I
opted for that instead of making a new entry.
Unfortunately, naming does not match precisely.
Thanks for the review! Ack. on everything I did not comment on.
Best,
Antheas
> Thanks,
> Rong
>
> > + else
> > + ret = 0;
> > +
> > + if (ret)
> > + dev_warn(dev, "failed to restore settings on resume: %d\n", ret);
> > +
> > + return 0;
> > +}
> > +
> > +static DEFINE_SIMPLE_DEV_PM_OPS(dptc_pm_ops, NULL, dptc_resume);
> > +
> > +static int dptc_probe(struct platform_device *pdev)
> > +{
> > + const struct dmi_system_id *dmi_match = dev_get_platdata(&pdev->dev);
> > + struct device *dev = &pdev->dev;
> > + struct dptc_priv *dptc;
> > + int i, ret;
> > +
> > + dptc = devm_kzalloc(dev, sizeof(*dptc), GFP_KERNEL);
> > + if (!dptc)
> > + return -ENOMEM;
> > +
> > + platform_set_drvdata(pdev, dptc);
> > +
> > + ret = devm_mutex_init(dev, &dptc->lock);
> > + if (ret)
> > + return ret;
> > +
> > + dptc->dev_limits = dmi_match->driver_data;
> > + dev_info(dev, "%s (%s)\n", dmi_match->ident,
> > + boot_cpu_data.x86_model_id);
> > +
> > + dptc->fw_attr_dev = device_create(&firmware_attributes_class,
> > + NULL, MKDEV(0, 0), NULL,
> > + DRIVER_NAME);
> > + if (IS_ERR(dptc->fw_attr_dev))
> > + return PTR_ERR(dptc->fw_attr_dev);
> > +
> > + ret = devm_add_action_or_reset(dev, dptc_fw_dev_unregister,
> > + dptc->fw_attr_dev);
> > + if (ret)
> > + return ret;
> > +
> > + dptc->fw_attr_kset = kset_create_and_add("attributes", NULL,
> > + &dptc->fw_attr_dev->kobj);
> > + if (!dptc->fw_attr_kset)
> > + return -ENOMEM;
> > +
> > + ret = devm_add_action_or_reset(dev, dptc_kset_unregister,
> > + dptc->fw_attr_kset);
> > + if (ret)
> > + return ret;
> > +
> > + for (i = 0; i < DPTC_NUM_PARAMS; i++) {
> > + dptc_setup_param_sysfs(dptc, &dptc->params[i], i);
> > + ret = sysfs_create_group(&dptc->fw_attr_kset->kobj,
> > + &dptc->params[i].group);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + dptc_setup_expanded_sysfs(dptc, &dptc->expanded_attr);
> > + ret = sysfs_create_group(&dptc->fw_attr_kset->kobj,
> > + &dptc->expanded_attr.group);
> > + if (ret)
> > + return ret;
> > +
> > + sysfs_attr_init(&dptc->save_settings_attr.attr);
> > + dptc->save_settings_attr.attr.name = "save_settings";
> > + dptc->save_settings_attr.attr.mode = 0644;
> > + dptc->save_settings_attr.show = dptc_save_settings_show;
> > + dptc->save_settings_attr.store = dptc_save_settings_store;
> > + ret = sysfs_create_file(&dptc->fw_attr_kset->kobj,
> > + &dptc->save_settings_attr.attr);
> > + if (ret)
> > + return ret;
> > +
> > + return 0;
> > +}
> > +
> > +static struct platform_driver dptc_driver = {
> > + .driver = {
> > + .name = DRIVER_NAME,
> > + .pm = pm_sleep_ptr(&dptc_pm_ops),
> > + },
> > + .probe = dptc_probe,
> > +};
> > +
> > +static int __init dptc_init(void)
> > +{
> > + const struct dmi_system_id *match;
> > + bool soc_found = false;
> > + int i, ret;
> > +
> > + match = dmi_first_match(dptc_dmi_table);
> > + if (!match)
> > + return -ENODEV;
> > +
> > + if (!acpi_has_method(NULL, ALIB_PATH)) {
> > + pr_warn("ALIB method not present\n");
> > + return -ENODEV;
> > + }
> > +
> > + for (i = 0; dptc_soc_table[i]; i++) {
> > + if (strstr(boot_cpu_data.x86_model_id,
> > + dptc_soc_table[i])) {
> > + soc_found = true;
> > + break;
> > + }
> > + }
> > + if (!soc_found) {
> > + pr_warn("unrecognized SoC '%s'\n",
> > + boot_cpu_data.x86_model_id);
> > + return -ENODEV;
> > + }
> > +
> > + dptc_pdev = platform_device_register_data(NULL, DRIVER_NAME, -1,
> > + match, sizeof(*match));
> > + if (IS_ERR(dptc_pdev))
> > + return PTR_ERR(dptc_pdev);
> > +
> > + ret = platform_driver_register(&dptc_driver);
> > + if (ret) {
> > + platform_device_unregister(dptc_pdev);
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void __exit dptc_exit(void)
> > +{
> > + platform_driver_unregister(&dptc_driver);
> > + platform_device_unregister(dptc_pdev);
> > +}
> > +
> > +module_init(dptc_init);
> > +module_exit(dptc_exit);
> > +
> > +MODULE_AUTHOR("Antheas Kapenekakis <lkml@xxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("AMD DPTCi ACPI Driver");
> > +MODULE_LICENSE("GPL");
>