ACPI: add support for configfs

Register the ACPI subsystem with configfs.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

5 files changed, 70 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/configfs-acpi b/Documentation/ABI/testing/configfs-acpi
new file mode 100644
index 000000000000..17b19dc2822d
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-acpi
@@ -0,0 +1,7 @@
+What:           /config/acpi
+Date:           July 2016
+KernelVersion:  4.8
+Contact:        linux-acpi@vger.kernel.org
+Description:
+                This represents the ACPI subsystem entry point directory. It
+                contains sub-groups corresponding to ACPI configurable options.
diff --git a/MAINTAINERS b/MAINTAINERS
index e1b090f86e0d..d01d8e2cf268 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -288,6 +288,7 @@ F:	include/linux/acpi.h
 F:      include/acpi/
 F:      Documentation/acpi/
 F:      Documentation/ABI/testing/sysfs-bus-acpi
+F:      Documentation/ABI/testing/configfs-acpi
 F:      drivers/pci/*acpi*
 F:      drivers/pci/*/*acpi*
 F:      drivers/pci/*/*/*acpi*
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 0a8e41a52d09..b420e5dd8a56 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -524,4 +524,12 @@ config XPOWER_PMIC_OPREGION
 
 endif
 
+config ACPI_CONFIGFS
+        tristate "ACPI configfs support"
+        select CONFIGFS_FS
+        help
+          Select this option to enable support for ACPI configuration from
+          userspace. The configurable ACPI groups will be visible under
+          /config/acpi, assuming configfs is mounted under /config.
+
 endif   # ACPI
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 251ce85a66fb..1dc2173ad8d0 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -99,5 +99,6 @@ obj-$(CONFIG_ACPI_EXTLOG)	+= acpi_extlog.o
 obj-$(CONFIG_PMIC_OPREGION)     += pmic/intel_pmic.o
 obj-$(CONFIG_CRC_PMIC_OPREGION) += pmic/intel_pmic_crc.o
 obj-$(CONFIG_XPOWER_PMIC_OPREGION) += pmic/intel_pmic_xpower.o
+obj-$(CONFIG_ACPI_CONFIGFS)     += configfs.o
 
 video-objs                      += acpi_video.o video_detect.o
diff --git a/drivers/acpi/configfs.c b/drivers/acpi/configfs.c
new file mode 100644
index 000000000000..44b463f6fca5
--- /dev/null
+++ b/drivers/acpi/configfs.c
@@ -0,0 +1,53 @@
+/*
+ * ACPI configfs support
+ *
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/configfs.h>
+#include <linux/acpi.h>
+
+static struct config_item_type acpi_root_group_type = {
+        .ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem acpi_configfs = {
+        .su_group = {
+                .cg_item = {
+                        .ci_namebuf = "acpi",
+                        .ci_type = &acpi_root_group_type,
+                },
+        },
+        .su_mutex = __MUTEX_INITIALIZER(acpi_configfs.su_mutex),
+};
+
+static int __init acpi_configfs_init(void)
+{
+        int ret;
+        struct config_group *root = &acpi_configfs.su_group;
+
+        config_group_init(root);
+
+        ret = configfs_register_subsystem(&acpi_configfs);
+        if (ret)
+                return ret;
+
+        return 0;
+}
+module_init(acpi_configfs_init);
+
+static void __exit acpi_configfs_exit(void)
+{
+        configfs_unregister_subsystem(&acpi_configfs);
+}
+module_exit(acpi_configfs_exit);
+
+MODULE_AUTHOR("Octavian Purdila <octavian.purdila@intel.com>");
+MODULE_DESCRIPTION("ACPI configfs support");
+MODULE_LICENSE("GPL v2");