[PATCH v8 2/5] iio: core: Introduce IIO configfs support

[Daniel Baluta <daniel.baluta@intel.com>]

This creates an IIO configfs subystem named "iio", with a default
"triggers" group. Next patches will add trigger types support,
allowing new triggers creation using configfs.

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
---
 drivers/iio/Kconfig                 |  8 +++++
 drivers/iio/Makefile                |  1 +
 drivers/iio/industrialio-configfs.c | 68 +++++++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+)
 create mode 100644 drivers/iio/industrialio-configfs.c

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 66792e7..7a4815a 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -22,6 +22,14 @@ if IIO_BUFFER
 	source "drivers/iio/buffer/Kconfig"
 endif # IIO_BUFFER
 
+config IIO_CONFIGFS
+	bool "Enable IIO configuration via configfs"
+	select CONFIGFS_FS
+	help
+	  This allows configuring various IIO bits through configfs
+	  (e.g. software triggers). For more info see
+	  Documentation/iio/iio_configfs.txt.
+
 config IIO_TRIGGER
 	bool "Enable triggered sampling support"
 	help
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index aeca726..e109f95 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -5,6 +5,7 @@
 obj-$(CONFIG_IIO) += industrialio.o
 industrialio-y := industrialio-core.o industrialio-event.o inkern.o
 industrialio-$(CONFIG_IIO_BUFFER) += industrialio-buffer.o
+industrialio-$(CONFIG_IIO_CONFIGFS) += industrialio-configfs.o
 industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o
 
 obj-$(CONFIG_IIO_TRIGGERED_EVENT) += industrialio-triggered-event.o
diff --git a/drivers/iio/industrialio-configfs.c b/drivers/iio/industrialio-configfs.c
new file mode 100644
index 0000000..211b52e
--- /dev/null
+++ b/drivers/iio/industrialio-configfs.c
@@ -0,0 +1,68 @@
+/*
+ * Industrial I/O configfs bits
+ *
+ * Copyright (c) 2015 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/configfs.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kmod.h>
+#include <linux/slab.h>
+
+#include <linux/iio/iio.h>
+
+static struct config_item_type iio_triggers_group_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+struct config_group iio_triggers_group = {
+	.cg_item = {
+		.ci_namebuf = "triggers",
+		.ci_type = &iio_triggers_group_type,
+	},
+};
+EXPORT_SYMBOL(iio_triggers_group);
+
+static struct config_group *iio_root_default_groups[] = {
+	&iio_triggers_group,
+	NULL
+};
+
+static struct config_item_type iio_root_group_type = {
+	.ct_owner       = THIS_MODULE,
+};
+
+static struct configfs_subsystem iio_configfs_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "iio",
+			.ci_type = &iio_root_group_type,
+		},
+		.default_groups = iio_root_default_groups,
+	},
+	.su_mutex = __MUTEX_INITIALIZER(iio_configfs_subsys.su_mutex),
+};
+
+static int __init iio_configfs_init(void)
+{
+	config_group_init(&iio_triggers_group);
+	config_group_init(&iio_configfs_subsys.su_group);
+
+	return configfs_register_subsystem(&iio_configfs_subsys);
+}
+module_init(iio_configfs_init);
+
+static void __exit iio_configfs_exit(void)
+{
+	configfs_unregister_subsystem(&iio_configfs_subsys);
+}
+module_exit(iio_configfs_exit);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
+MODULE_DESCRIPTION("Industrial I/O configfs support");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1