ACPI: platform: Add platform profile support

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>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
[ rjw: Use full words in enum values names ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 181 insertions, 0 deletions

diff --git a/drivers/acpi/platform_profile.c b/drivers/acpi/platform_profile.c
new file mode 100644
index 000000000000..91be50a32cc8
--- /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/bits.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/platform_profile.h>
+#include <linux/sysfs.h>
+
+static const struct platform_profile_handler *cur_profile;
+static DEFINE_MUTEX(profile_lock);
+
+static const char * const profile_names[] = {
+	[PLATFORM_PROFILE_LOW_POWER] = "low-power",
+	[PLATFORM_PROFILE_COOL] = "cool",
+	[PLATFORM_PROFILE_QUIET] = "quiet",
+	[PLATFORM_PROFILE_BALANCED] = "balanced",
+	[PLATFORM_PROFILE_PERFORMANCE] = "performance",
+};
+static_assert(ARRAY_SIZE(profile_names) == PLATFORM_PROFILE_LAST);
+
+static ssize_t platform_profile_choices_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	int len = 0;
+	int err, i;
+
+	err = mutex_lock_interruptible(&profile_lock);
+	if (err)
+		return err;
+
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	for_each_set_bit(i, cur_profile->choices, PLATFORM_PROFILE_LAST) {
+		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 = PLATFORM_PROFILE_BALANCED;
+	int err;
+
+	err = mutex_lock_interruptible(&profile_lock);
+	if (err)
+		return err;
+
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	err = cur_profile->profile_get(&profile);
+	mutex_unlock(&profile_lock);
+	if (err)
+		return err;
+
+	/* Check that profile is valid index */
+	if (WARN_ON((profile < 0) || (profile >= ARRAY_SIZE(profile_names))))
+		return -EIO;
+
+	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;
+
+	err = mutex_lock_interruptible(&profile_lock);
+	if (err)
+		return err;
+
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	/* Scan for a matching profile */
+	i = sysfs_match_string(profile_names, buf);
+	if (i < 0) {
+		mutex_unlock(&profile_lock);
+		return -EINVAL;
+	}
+
+	/* Check that platform supports this profile choice */
+	if (!test_bit(i, cur_profile->choices)) {
+		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
+};
+
+void platform_profile_notify(void)
+{
+	if (!cur_profile)
+		return;
+	sysfs_notify(acpi_kobj, NULL, "platform_profile");
+}
+EXPORT_SYMBOL_GPL(platform_profile_notify);
+
+int platform_profile_register(const struct platform_profile_handler *pprof)
+{
+	int err;
+
+	mutex_lock(&profile_lock);
+	/* We can only have one active profile */
+	if (cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -EEXIST;
+	}
+
+	/* Sanity check the profile handler field are set */
+	if (!pprof || bitmap_empty(pprof->choices, PLATFORM_PROFILE_LAST) ||
+		!pprof->profile_set || !pprof->profile_get) {
+		mutex_unlock(&profile_lock);
+		return -EINVAL;
+	}
+
+	err = sysfs_create_group(acpi_kobj, &platform_profile_group);
+	if (err) {
+		mutex_unlock(&profile_lock);
+		return err;
+	}
+
+	cur_profile = pprof;
+	mutex_unlock(&profile_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(platform_profile_register);
+
+int platform_profile_remove(void)
+{
+	mutex_lock(&profile_lock);
+	if (!cur_profile) {
+		mutex_unlock(&profile_lock);
+		return -ENODEV;
+	}
+
+	sysfs_remove_group(acpi_kobj, &platform_profile_group);
+	cur_profile = NULL;
+	mutex_unlock(&profile_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(platform_profile_remove);
+
+MODULE_AUTHOR("Mark Pearson <markpearson@lenovo.com>");
+MODULE_LICENSE("GPL");