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

[Mark Pearson <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>
---
 MAINTAINERS                      |   8 ++
 drivers/acpi/Kconfig             |  19 ++++
 drivers/acpi/Makefile            |   1 +
 drivers/acpi/platform_profile.c  | 172 +++++++++++++++++++++++++++++++
 include/linux/platform_profile.h |  36 +++++++
 5 files changed, 236 insertions(+)
 create mode 100644 drivers/acpi/platform_profile.c
 create mode 100644 include/linux/platform_profile.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 9a54806ebf02..e731ac1c4447 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -436,6 +436,14 @@ S:	Orphan
 F:	drivers/platform/x86/wmi.c
 F:	include/uapi/linux/wmi.h
 
+ACPI PLATFORM PROFILE DRIVER
+M:	Mark Pearson <markpearons@lenovo.com>
+L:	linux-acpi@vger.kernel.org
+S:	Supported
+W:	https://01.org/linux-acpi
+B:	https://bugzilla.kernel.org
+F:	drivers/acpi/platform_profile.c
+
 AD1889 ALSA SOUND DRIVER
 L:	linux-parisc@vger.kernel.org
 S:	Maintained
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 7540a5179a47..b10a8e0863cf 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -601,3 +601,22 @@ 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 9a957544e357..82dbdc0300ed 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
 obj-$(CONFIG_ACPI_SPCR_TABLE)	+= spcr.o
 obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
 obj-$(CONFIG_ACPI_PPTT) 	+= pptt.o
+obj-$(CONFIG_ACPI_PLATFORM_PROFILE) 	+= platform_profile.o
 
 # processor has its own "processor." module_param namespace
 processor-y			:= processor_driver.o
diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
new file mode 100644
index 000000000000..3c460c0a3857
--- /dev/null
+++ b/drivers/acpi/platform_profile.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ *  platform_profile.c - Platform profile sysfs interface
+ */
+
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/device.h>
+#include <linux/acpi.h>
+#include <linux/mutex.h>
+#include <acpi/acpi_bus.h>
+#include <linux/platform_profile.h>
+
+struct platform_profile *cur_profile;
+DEFINE_MUTEX(profile_lock);
+
+/* Ensure the first char of each profile is unique */
+static char *profile_str[] = {
+	"Low-power",
+	"Cool",
+	"Quiet",
+	"Balance",
+	"Performance",
+	"Unknown"
+};
+
+static ssize_t platform_profile_choices_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	int i;
+	int ret, count = 0;
+
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	if (!cur_profile->choices) {
+		mutex_unlock(&profile_lock);
+		return snprintf(buf, PAGE_SIZE, "None");
+	}
+
+	for (i = profile_low; i < profile_unknown; i++) {
+		if (cur_profile->choices & (1 << i)) {
+			ret = snprintf(buf+count, PAGE_SIZE, "%s ", profile_str[i]);
+			if (ret < 0)
+				break;
+			count += ret;
+		}
+	}
+	mutex_unlock(&profile_lock);
+	return count;
+}
+
+static ssize_t platform_profile_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	enum profile_option profile = profile_unknown;
+
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+	if (cur_profile->profile_get)
+		profile = cur_profile->profile_get();
+	mutex_unlock(&profile_lock);
+
+	return snprintf(buf, PAGE_SIZE, "%s", profile_str[profile]);
+}
+
+static ssize_t platform_profile_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	enum profile_option profile;
+
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	/* Scan for a matching profile */
+	for (profile = profile_low; profile < profile_unknown; profile++) {
+		if (toupper(buf[0]) == profile_str[profile][0])
+			break;
+	}
+	if (profile == profile_unknown) {
+		mutex_unlock(&profile_lock);
+		return -EINVAL;
+	}
+
+	if (cur_profile->profile_set)
+		cur_profile->profile_set(profile);
+
+	mutex_unlock(&profile_lock);
+	return count;
+}
+
+static DEVICE_ATTR_RO(platform_profile_choices);
+static DEVICE_ATTR_RW(platform_profile);
+
+static struct attribute *platform_profile_attributes[] = {
+	&dev_attr_platform_profile_choices.attr,
+	&dev_attr_platform_profile.attr,
+	NULL,
+};
+
+static const struct attribute_group platform_profile_attr_group = {
+	.attrs = platform_profile_attributes,
+};
+
+int platform_profile_notify(void)
+{
+	if (!cur_profile)
+		return -ENODEV;
+	sysfs_notify(acpi_kobj, NULL, "platform_profile");
+	return 0;
+}
+EXPORT_SYMBOL_GPL(platform_profile_notify);
+
+int platform_profile_register(struct platform_profile *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_attr_group);
+}
+EXPORT_SYMBOL_GPL(platform_profile_register);
+
+int platform_profile_unregister(void)
+{
+	mutex_lock(&profile_lock);
+	sysfs_remove_group(acpi_kobj, &platform_profile_attr_group);
+	cur_profile = NULL;
+	mutex_unlock(&profile_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(platform_profile_unregister);
+
+static int __init platform_profile_init(void)
+{
+	cur_profile = NULL;
+	return 0;
+}
+
+static void platform_profile_exit(void)
+{
+	sysfs_remove_group(acpi_kobj, &platform_profile_attr_group);
+	cur_profile = NULL;
+}
+
+MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>");
+MODULE_LICENSE("GPL");
+
+module_init(platform_profile_init);
+module_exit(platform_profile_exit);
diff --git a/include/linux/platform_profile.h b/include/linux/platform_profile.h
new file mode 100644
index 000000000000..347a12172c09
--- /dev/null
+++ b/include/linux/platform_profile.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * platform_profile.h - platform profile sysfs interface
+ *
+ * See Documentation/ABI/testing/sysfs-platform_profile for more information.
+ */
+
+#ifndef _PLATFORM_PROFILE_H_
+#define _PLATFORM_PROFILE_H_
+
+/*
+ * If more options are added please update profile_str
+ * array in platform-profile.c
+ */
+
+enum profile_option {
+	profile_low,
+	profile_cool,
+	profile_quiet,
+	profile_balance,
+	profile_perform,
+	profile_unknown /* Must always be last */
+};
+
+struct platform_profile {
+	unsigned int choices; /* bitmap of available choices */
+	int cur_profile;      /* Current active profile */
+	int (*profile_get)(void);
+	int (*profile_set)(int profile);
+};
+
+extern int platform_profile_register(struct platform_profile *pprof);
+extern int platform_profile_unregister(void);
+extern int platform_profile_notify(void);
+
+#endif  /*_PLATFORM_PROFILE_H_*/
-- 
2.28.0