iio: Add support for creating IIO devices via configfs

This is similar with support for creating triggers via configfs.
Devices will be hosted under:
	* /config/iio/devices

We allow users to register "device types" under:
	* /config/iio/devices/<device_types>/

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 505e921f0b19e701382fd820ab54a4c6525d8838..6743b18194fb0b2545639902b11654505990144e 100644 (file)
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -46,6 +46,14 @@ config IIO_CONSUMERS_PER_TRIGGER
        This value controls the maximum number of consumers that a
        given trigger may handle. Default is 2.
 
+config IIO_SW_DEVICE
+       tristate "Enable software IIO device support"
+       select IIO_CONFIGFS
+       help
+        Provides IIO core support for software devices. A software
+        device can be created via configfs or directly by a driver
+        using the API provided.
+
 config IIO_SW_TRIGGER
        tristate "Enable software triggers support"
        select IIO_CONFIGFS

diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 20f649073462e9e3e69f872a27115ad91fe95980..87e4c4369e2f5122ba36f73f63ecbc551760533b 100644 (file)
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -8,6 +8,7 @@ industrialio-$(CONFIG_IIO_BUFFER) += industrialio-buffer.o
 industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o
 
 obj-$(CONFIG_IIO_CONFIGFS) += industrialio-configfs.o
+obj-$(CONFIG_IIO_SW_DEVICE) += industrialio-sw-device.o
 obj-$(CONFIG_IIO_SW_TRIGGER) += industrialio-sw-trigger.o
 obj-$(CONFIG_IIO_TRIGGERED_EVENT) += industrialio-triggered-event.o
 

diff --git a/drivers/iio/industrialio-sw-device.c b/drivers/iio/industrialio-sw-device.c
new file mode 100644 (file)
index 0000000..81b49cf
--- /dev/null
+++ b/drivers/iio/industrialio-sw-device.c
@@ -0,0 +1,182 @@
+/*
+ * The Industrial I/O core, software IIO devices functions
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include <linux/iio/sw_device.h>
+#include <linux/iio/configfs.h>
+#include <linux/configfs.h>
+
+static struct config_group *iio_devices_group;
+static struct config_item_type iio_device_type_group_type;
+
+static struct config_item_type iio_devices_group_type = {
+       .ct_owner = THIS_MODULE,
+};
+
+static LIST_HEAD(iio_device_types_list);
+static DEFINE_MUTEX(iio_device_types_lock);
+
+static
+struct iio_sw_device_type *__iio_find_sw_device_type(const char *name,
+                                                    unsigned len)
+{
+       struct iio_sw_device_type *d = NULL, *iter;
+
+       list_for_each_entry(iter, &iio_device_types_list, list)
+               if (!strcmp(iter->name, name)) {
+                       d = iter;
+                       break;
+               }
+
+       return d;
+}
+
+int iio_register_sw_device_type(struct iio_sw_device_type *d)
+{
+       struct iio_sw_device_type *iter;
+       int ret = 0;
+
+       mutex_lock(&iio_device_types_lock);
+       iter = __iio_find_sw_device_type(d->name, strlen(d->name));
+       if (iter)
+               ret = -EBUSY;
+       else
+               list_add_tail(&d->list, &iio_device_types_list);
+       mutex_unlock(&iio_device_types_lock);
+
+       if (ret)
+               return ret;
+
+       d->group = configfs_register_default_group(iio_devices_group, d->name,
+                                               &iio_device_type_group_type);
+       if (IS_ERR(d->group))
+               ret = PTR_ERR(d->group);
+
+       return ret;
+}
+EXPORT_SYMBOL(iio_register_sw_device_type);
+
+void iio_unregister_sw_device_type(struct iio_sw_device_type *dt)
+{
+       struct iio_sw_device_type *iter;
+
+       mutex_lock(&iio_device_types_lock);
+       iter = __iio_find_sw_device_type(dt->name, strlen(dt->name));
+       if (iter)
+               list_del(&dt->list);
+       mutex_unlock(&iio_device_types_lock);
+
+       configfs_unregister_default_group(dt->group);
+}
+EXPORT_SYMBOL(iio_unregister_sw_device_type);
+
+static
+struct iio_sw_device_type *iio_get_sw_device_type(const char *name)
+{
+       struct iio_sw_device_type *dt;
+
+       mutex_lock(&iio_device_types_lock);
+       dt = __iio_find_sw_device_type(name, strlen(name));
+       if (dt && !try_module_get(dt->owner))
+               dt = NULL;
+       mutex_unlock(&iio_device_types_lock);
+
+       return dt;
+}
+
+struct iio_sw_device *iio_sw_device_create(const char *type, const char *name)
+{
+       struct iio_sw_device *d;
+       struct iio_sw_device_type *dt;
+
+       dt = iio_get_sw_device_type(type);
+       if (!dt) {
+               pr_err("Invalid device type: %s\n", type);
+               return ERR_PTR(-EINVAL);
+       }
+       d = dt->ops->probe(name);
+       if (IS_ERR(d))
+               goto out_module_put;
+
+       d->device_type = dt;
+
+       return d;
+out_module_put:
+       module_put(dt->owner);
+       return d;
+}
+EXPORT_SYMBOL(iio_sw_device_create);
+
+void iio_sw_device_destroy(struct iio_sw_device *d)
+{
+       struct iio_sw_device_type *dt = d->device_type;
+
+       dt->ops->remove(d);
+       module_put(dt->owner);
+}
+EXPORT_SYMBOL(iio_sw_device_destroy);
+
+static struct config_group *device_make_group(struct config_group *group,
+                                             const char *name)
+{
+       struct iio_sw_device *d;
+
+       d = iio_sw_device_create(group->cg_item.ci_name, name);
+       if (IS_ERR(d))
+               return ERR_CAST(d);
+
+       config_item_set_name(&d->group.cg_item, "%s", name);
+
+       return &d->group;
+}
+
+static void device_drop_group(struct config_group *group,
+                             struct config_item *item)
+{
+       struct iio_sw_device *d = to_iio_sw_device(item);
+
+       iio_sw_device_destroy(d);
+       config_item_put(item);
+}
+
+static struct configfs_group_operations device_ops = {
+       .make_group     = &device_make_group,
+       .drop_item      = &device_drop_group,
+};
+
+static struct config_item_type iio_device_type_group_type = {
+       .ct_group_ops = &device_ops,
+       .ct_owner       = THIS_MODULE,
+};
+
+static int __init iio_sw_device_init(void)
+{
+       iio_devices_group =
+               configfs_register_default_group(&iio_configfs_subsys.su_group,
+                                               "devices",
+                                               &iio_devices_group_type);
+       return PTR_ERR_OR_ZERO(iio_devices_group);
+}
+module_init(iio_sw_device_init);
+
+static void __exit iio_sw_device_exit(void)
+{
+       configfs_unregister_default_group(iio_devices_group);
+}
+module_exit(iio_sw_device_exit);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
+MODULE_DESCRIPTION("Industrial I/O software devices support");
+MODULE_LICENSE("GPL v2");

diff --git a/include/linux/iio/sw_device.h b/include/linux/iio/sw_device.h
new file mode 100644 (file)
index 0000000..23ca415
--- /dev/null
+++ b/include/linux/iio/sw_device.h
@@ -0,0 +1,70 @@
+/*
+ * Industrial I/O software device interface
+ *
+ * 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.
+ */
+
+#ifndef __IIO_SW_DEVICE
+#define __IIO_SW_DEVICE
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/configfs.h>
+
+#define module_iio_sw_device_driver(__iio_sw_device_type) \
+       module_driver(__iio_sw_device_type, iio_register_sw_device_type, \
+                     iio_unregister_sw_device_type)
+
+struct iio_sw_device_ops;
+
+struct iio_sw_device_type {
+       const char *name;
+       struct module *owner;
+       const struct iio_sw_device_ops *ops;
+       struct list_head list;
+       struct config_group *group;
+};
+
+struct iio_sw_device {
+       struct iio_dev *device;
+       struct iio_sw_device_type *device_type;
+       struct config_group group;
+};
+
+struct iio_sw_device_ops {
+       struct iio_sw_device* (*probe)(const char *);
+       int (*remove)(struct iio_sw_device *);
+};
+
+static inline
+struct iio_sw_device *to_iio_sw_device(struct config_item *item)
+{
+       return container_of(to_config_group(item), struct iio_sw_device,
+                           group);
+}
+
+int iio_register_sw_device_type(struct iio_sw_device_type *dt);
+void iio_unregister_sw_device_type(struct iio_sw_device_type *dt);
+
+struct iio_sw_device *iio_sw_device_create(const char *, const char *);
+void iio_sw_device_destroy(struct iio_sw_device *);
+
+int iio_sw_device_type_configfs_register(struct iio_sw_device_type *dt);
+void iio_sw_device_type_configfs_unregister(struct iio_sw_device_type *dt);
+
+static inline
+void iio_swd_group_init_type_name(struct iio_sw_device *d,
+                                 const char *name,
+                                 struct config_item_type *type)
+{
+#ifdef CONFIG_CONFIGFS_FS
+       config_group_init_type_name(&d->group, name, type);
+#endif
+}
+
+#endif /* __IIO_SW_DEVICE */