[PATCH v2 2/3] ACPI: platform-profile: Add platform profile support

From: Mark Pearson <markpearson@lenovo.com>
To: <markpearson@lenovo.com>
Cc: <rjw@rjwysocki.net>, <hdegoede@redhat.com>,
	<mgross@linux.intel.com>, <linux-acpi@vger.kernel.org>,
	<mario.limonciello@dell.com>, <eliadevito@gmail.com>,
	<hadess@hadess.net>, <bberg@redhat.com>,
	<platform-driver-x86@vger.kernel.org>, <dvhart@infradead.org>
Subject: [PATCH v2 2/3] ACPI: platform-profile: Add platform profile support
Date: Sat, 14 Nov 2020 10:01:01 -0500	[thread overview]
Message-ID: <20201114150102.340618-2-markpearson@lenovo.com> (raw)
In-Reply-To: <20201114150102.340618-1-markpearson@lenovo.com>

This is the initial implementation of the platform-profile feature.
It provides the details discussed and outlined in the
sysfs-platform_profile document.

Many modern systems have the ability to modify the operating profile to
control aspects like fan speed, temperature and power levels. This
module provides a common sysfs interface that platform modules can register
against to control their individual profile options.

Signed-off-by: Mark Pearson <markpearson@lenovo.com>
---
Changes in v2:
 Address (hopefully) all recommendations from review including:
 - reorder includes list alphabetically
 - make globals statics and use const as required
 - change profile name scanning to use full string
 - clean up profile name lists to remove unwanted additions
 - use sysfs_emit and sysfs_emit_at appropriately (much nicer!)
 - improve error handling. Return errors to user in all cases and use
   better error codes where appropriate (ENOOPSUPP)
 - clean up sysfs output for better readability
 - formatting fixes where needed
 - improve structure and enum names to be clearer
 - remove cur_profile field from structure. It is now local to the
   actual platform driver file (patch 3 in series)
 - improve checking so if future profile options are added profile_names
   will be updated as well.
 - move CONFIG option next to ACPI_THERMAL as it seemed slightly related
 - removed MAINTAINERS update as not appropriate (note warning message
   is seen when running checkpatch)

Big thank you to reviewers for all the suggestions.

 drivers/acpi/Kconfig            |  33 ++++++
 drivers/acpi/Makefile           |   1 +
 drivers/acpi/platform_profile.c | 181 ++++++++++++++++++++++++++++++++
 3 files changed, 215 insertions(+)
 create mode 100644 drivers/acpi/platform_profile.c

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index edf1558c1105..73a99af5ec2c 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -326,6 +326,20 @@ config ACPI_THERMAL
 	  To compile this driver as a module, choose M here:
 	  the module will be called thermal.
 
+config ACPI_PLATFORM_PROFILE
+	tristate "ACPI Platform Profile Driver"
+	default y
+	help
+	  This driver adds support for platform-profiles on platforms that
+	  support it.
+	  Platform-profiles can be used to control the platform behaviour. For
+	  example whether to operate in a lower power mode, in a higher
+	  power performance mode or between the two.
+	  This driver provides the sysfs interface and is used as the registration
+	  point for platform specific drivers.
+	  Which profiles are supported is determined on a per-platform basis and
+	  should be obtained from the platform specific driver.
+
 config ACPI_CUSTOM_DSDT_FILE
 	string "Custom DSDT Table file to include"
 	default ""
@@ -538,3 +552,22 @@ config X86_PM_TIMER
 
 	  You should nearly always say Y here because many modern
 	  systems require this timer.
+
+config ACPI_PLATFORM_PROFILE
+	tristate "ACPI Platform Profile Driver"
+	default y
+	help
+	  This driver adds support for platform-profiles on platforms that
+	  support it.
+
+	  Platform-profiles can be used to control the platform behaviour. For
+	  example whether to operate in a lower power mode, in a higher
+	  power performance mode or between the two.
+
+	  This driver provides the sysfs interface and is used as the registration
+	  point for platform specific drivers.
+
+	  Which profiles are supported is determined on a per-platform basis and
+	  should be obtained from the platform specific driver.
+
+
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 44e412506317..c64a8af106c0 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -78,6 +78,7 @@ obj-$(CONFIG_ACPI_PCI_SLOT)	+= pci_slot.o
 obj-$(CONFIG_ACPI_PROCESSOR)	+= processor.o
 obj-$(CONFIG_ACPI)		+= container.o
 obj-$(CONFIG_ACPI_THERMAL)	+= thermal.o
+obj-$(CONFIG_ACPI_PLATFORM_PROFILE) 	+= platform_profile.o
 obj-$(CONFIG_ACPI_NFIT)		+= nfit/
 obj-$(CONFIG_ACPI_NUMA)		+= numa/
 obj-$(CONFIG_ACPI)		+= acpi_memhotplug.o
diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
new file mode 100644
index 000000000000..e4bbee48c0f8
--- /dev/null
+++ b/drivers/acpi/platform_profile.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* Platform profile sysfs interface */
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_profile.h>
+#include <linux/printk.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+
+static struct platform_profile_handler *cur_profile;
+static DEFINE_MUTEX(profile_lock);
+
+/* Ensure the first char of each profile is unique */
+static const char * const profile_names[] = {
+	[profile_low] = "low-power",
+	[profile_cool] = "cool",
+	[profile_quiet] = "quiet",
+	[profile_balance] = "balance",
+	[profile_perform] = "performance",
+};
+static_assert(ARRAY_SIZE(profile_names) == profile_perform+1);
+
+static ssize_t platform_profile_choices_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	int len = 0;
+	int i;
+
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	if (!cur_profile->choices) {
+		mutex_unlock(&profile_lock);
+		return sysfs_emit(buf, "\n");
+	}
+
+	for (i = profile_low; i <= profile_perform; i++) {
+		if (cur_profile->choices & BIT(i)) {
+			if (len == 0)
+				len += sysfs_emit_at(buf, len, "%s",  profile_names[i]);
+			else
+				len += sysfs_emit_at(buf, len, " %s",  profile_names[i]);
+		}
+	}
+	len += sysfs_emit_at(buf, len, "\n");
+	mutex_unlock(&profile_lock);
+
+	return len;
+}
+
+static ssize_t platform_profile_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	enum platform_profile_option profile;
+	int err;
+
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -EOPNOTSUPP;
+	}
+
+	if (!cur_profile->profile_get) {
+		mutex_unlock(&profile_lock);
+		return -EOPNOTSUPP;
+	}
+
+	err = cur_profile->profile_get(&profile);
+	mutex_unlock(&profile_lock);
+	if (err < 0)
+		return err;
+
+	return sysfs_emit(buf, "%s\n", profile_names[profile]);
+}
+
+static ssize_t platform_profile_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	int err, i;
+
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -EOPNOTSUPP;
+	}
+
+	/* Scan for a matching profile */
+	i = sysfs_match_string(profile_names, buf);
+	if (i < 0) {
+		mutex_unlock(&profile_lock);
+		return -EINVAL;
+	}
+
+	if (!cur_profile->profile_set) {
+		mutex_unlock(&profile_lock);
+		return -EOPNOTSUPP;
+	}
+
+	err = cur_profile->profile_set(i);
+	mutex_unlock(&profile_lock);
+	if (err)
+		return err;
+
+	return count;
+}
+
+static DEVICE_ATTR_RO(platform_profile_choices);
+static DEVICE_ATTR_RW(platform_profile);
+
+static struct attribute *platform_profile_attrs[] = {
+	&dev_attr_platform_profile_choices.attr,
+	&dev_attr_platform_profile.attr,
+	NULL
+};
+
+static const struct attribute_group platform_profile_group = {
+	.attrs = platform_profile_attrs
+};
+
+int platform_profile_notify(void)
+{
+	if (!cur_profile)
+		return -EOPNOTSUPP;
+	sysfs_notify(acpi_kobj, NULL, "platform_profile");
+	return 0;
+}
+EXPORT_SYMBOL_GPL(platform_profile_notify);
+
+int platform_profile_register(struct platform_profile_handler *pprof)
+{
+	mutex_lock(&profile_lock);
+	/* We can only have one active profile */
+	if (cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -EEXIST;
+	}
+
+	cur_profile = pprof;
+	mutex_unlock(&profile_lock);
+	return sysfs_create_group(acpi_kobj, &platform_profile_group);
+}
+EXPORT_SYMBOL_GPL(platform_profile_register);
+
+int platform_profile_unregister(void)
+{
+	mutex_lock(&profile_lock);
+	sysfs_remove_group(acpi_kobj, &platform_profile_group);
+	cur_profile = NULL;
+	mutex_unlock(&profile_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(platform_profile_unregister);
+
+static int __init platform_profile_init(void)
+{
+	return 0;
+}
+module_init(platform_profile_init);
+
+static void __exit platform_profile_exit(void)
+{
+	sysfs_remove_group(acpi_kobj, &platform_profile_group);
+	cur_profile = NULL;
+}
+module_exit(platform_profile_exit);
+
+MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>");
+MODULE_LICENSE("GPL");
-- 
2.25.1

