[PATCH 1/3] iio: configfs: Add configfs support to IIO

[Daniel Baluta]

This creates an IIO configfs subsystem named "iio", which has one default
group named "triggers". This allows us to easily create/destroy software
triggers. One must create a driver which implements iio_configfs_trigger.h
interface and then add its trigger type to IIO configfs core.

See Documentation/iio/iio_configfs.txt for more details on how configfs
support for IIO works.

Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx>
---
 drivers/iio/Kconfig                      |   8 +
 drivers/iio/Makefile                     |   1 +
 drivers/iio/industrialio-configfs.c      | 297 +++++++++++++++++++++++++++++++
 include/linux/iio/iio_configfs_trigger.h |  48 +++++
 4 files changed, 354 insertions(+)
 create mode 100644 drivers/iio/industrialio-configfs.c
 create mode 100644 include/linux/iio/iio_configfs_trigger.h

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 4132935..39f1b69 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -18,6 +18,14 @@ config IIO_BUFFER
 	  Provide core support for various buffer based data
 	  acquisition methods.
 
+config IIO_CONFIGFS
+	tristate "Enable IIO configuration via configfs"
+	select CONFIGFS_FS
+	help
+	  This allows configuring various IIO bits through configfs
+	  (e.g software trigger creation / destruction). For more info
+	  see Documentation/iio/iio_configfs.txt.
+
 if IIO_BUFFER
 
 config IIO_BUFFER_CB
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 698afc2..90cc407 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
 industrialio-$(CONFIG_IIO_BUFFER_CB) += buffer_cb.o
 
diff --git a/drivers/iio/industrialio-configfs.c b/drivers/iio/industrialio-configfs.c
new file mode 100644
index 0000000..4d2133a
--- /dev/null
+++ b/drivers/iio/industrialio-configfs.c
@@ -0,0 +1,297 @@
+/*
+ * 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/slab.h>
+
+#include <linux/iio/iio_configfs_trigger.h>
+
+static const char *trigger_types[] =
+{
+	"none",
+};
+
+struct iio_configfs_ops iio_none_ops = {
+	.get_freq	= iio_none_get_freq,
+	.set_freq	= iio_none_set_freq,
+	.probe		= iio_none_probe,
+	.remove		= iio_none_remove,
+};
+
+struct iio_trigger_item {
+	struct config_item item;
+	struct iio_configfs_trigger_info *trigger_info;
+};
+
+static
+inline struct iio_trigger_item *to_iio_trigger_item(struct config_item *item)
+{
+	if (!item)
+		return NULL;
+	return container_of(item, struct iio_trigger_item, item);
+}
+
+static unsigned int iio_trigger_get_type(const char *type_str)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
+		if (!strncmp(trigger_types[i], type_str,
+			    strlen(trigger_types[i])))
+			return i;
+	}
+	return -EINVAL;
+}
+
+static
+void iio_trigger_set_configfs_ops(struct iio_configfs_trigger_info *trig_info,
+				  unsigned int type)
+{
+	switch (type) {
+	case IIO_TRIGGER_TYPE_NONE:
+		trig_info->configfs_ops = &iio_none_ops;
+		break;
+	default:
+		pr_err("Setting configfs ops failed! Unknown type %d\n", type);
+		break;
+	}
+}
+
+CONFIGFS_ATTR_STRUCT(iio_trigger_item);
+
+#define IIO_TRIGGER_ITEM_ATTR(_name, _mode, _show, _store) \
+struct iio_trigger_item_attribute iio_trigger_item_attr_##_name = \
+	__CONFIGFS_ATTR(_name, _mode, _show, _store)
+
+static ssize_t iio_trigger_item_type_read(struct iio_trigger_item *item,
+					  char *page)
+{
+	return sprintf(page, "%s\n", trigger_types[item->trigger_info->type]);
+}
+
+static ssize_t iio_trigger_item_type_write(struct iio_trigger_item *item,
+					   const char *page, size_t count)
+{
+	int type;
+
+	if (item->trigger_info->active)
+		return -EBUSY;
+
+	type = iio_trigger_get_type(page);
+	if (type < 0)
+		return -EINVAL;
+
+	item->trigger_info->type = type;
+
+	iio_trigger_set_configfs_ops(item->trigger_info, type);
+
+	return count;
+}
+
+static ssize_t iio_trigger_item_activate_read(struct iio_trigger_item *item,
+					      char *page)
+{
+	return sprintf(page, "%d\n", item->trigger_info->active);
+}
+
+static ssize_t iio_trigger_item_activate_write(struct iio_trigger_item *item,
+					       const char *page, size_t count)
+{
+	bool requested_action;
+	int ret;
+
+	ret = strtobool(page, &requested_action);
+	if (ret < 0)
+		return ret;
+
+	if (requested_action == item->trigger_info->active)
+		return -EINVAL;
+
+	if (requested_action)
+		item->trigger_info->configfs_ops->probe(item->trigger_info);
+	else
+		item->trigger_info->configfs_ops->remove(item->trigger_info);
+
+	item->trigger_info->active = requested_action;
+
+	return count;
+}
+
+static
+ssize_t iio_trigger_item_get_sampling_freq(struct iio_trigger_item *item,
+					   char *page)
+{
+	int ret;
+
+	if (!item->trigger_info->active)
+		return -ENODEV;
+
+	ret = item->trigger_info->configfs_ops->get_freq(item->trigger_info);
+	if (ret < 0)
+		return ret;
+	return sprintf(page, "%d\n", ret);
+}
+
+static
+ssize_t iio_trigger_item_set_sampling_freq(struct iio_trigger_item *item,
+					   const char *page,
+					   size_t count)
+{
+	int ret;
+	unsigned long freq;
+
+	if (!item->trigger_info->active)
+		return -ENODEV;
+
+	ret = kstrtoul(page, 10, &freq);
+	if (ret < 0)
+		return 0;
+
+	ret = item->trigger_info->configfs_ops->set_freq(item->trigger_info,
+							 freq);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+IIO_TRIGGER_ITEM_ATTR(type, S_IRUGO | S_IWUSR,
+		      iio_trigger_item_type_read,
+		      iio_trigger_item_type_write);
+
+IIO_TRIGGER_ITEM_ATTR(activate, S_IRUGO | S_IWUSR,
+		      iio_trigger_item_activate_read,
+		      iio_trigger_item_activate_write);
+
+IIO_TRIGGER_ITEM_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
+		      iio_trigger_item_get_sampling_freq,
+		      iio_trigger_item_set_sampling_freq);
+
+static struct configfs_attribute *iio_trigger_item_attrs[] = {
+	&iio_trigger_item_attr_type.attr,
+	&iio_trigger_item_attr_sampling_frequency.attr,
+	&iio_trigger_item_attr_activate.attr,
+	NULL
+};
+
+CONFIGFS_ATTR_OPS(iio_trigger_item);
+
+static struct configfs_item_operations iio_trigger_item_ops = {
+	.show_attribute = iio_trigger_item_attr_show,
+	.store_attribute = iio_trigger_item_attr_store,
+};
+
+static struct config_item_type iio_triggers_item_type;
+
+static struct config_item *iio_triggers_make_item(struct config_group *group,
+						  const char *name)
+{
+	struct iio_trigger_item *trigger_item;
+	struct iio_configfs_trigger_info *trigger_info;
+
+	trigger_item = kzalloc(sizeof(*trigger_item), GFP_KERNEL);
+	if (!trigger_item)
+		return ERR_PTR(-ENOMEM);
+	trigger_info = kzalloc(sizeof(*trigger_info), GFP_KERNEL);
+	if (!trigger_info)
+		goto out_free_trigger_item;
+
+	trigger_info->name = kstrdup(name, GFP_KERNEL);
+	if (!trigger_info->name)
+		goto out_free_trigger_info;
+
+	trigger_info->type = IIO_TRIGGER_TYPE_NONE;
+	trigger_info->configfs_ops = &iio_none_ops;
+
+	trigger_item->trigger_info = trigger_info;
+	config_item_init_type_name(&trigger_item->item, name,
+				   &iio_triggers_item_type);
+
+	return &trigger_item->item;
+out_free_trigger_info:
+	kfree(trigger_info);
+out_free_trigger_item:
+	kfree(trigger_item);
+	return ERR_PTR(-ENOMEM);
+}
+
+static void iio_triggers_drop_item(struct config_group *group,
+				   struct config_item *item)
+{
+	struct iio_trigger_item *trigger_item;
+
+	trigger_item = container_of(item, struct iio_trigger_item, item);
+
+	kfree(trigger_item->trigger_info->name);
+	kfree(trigger_item->trigger_info);
+	kfree(trigger_item);
+}
+
+static struct configfs_group_operations iio_triggers_group_ops = {
+	.make_item = iio_triggers_make_item,
+	.drop_item = iio_triggers_drop_item,
+};
+
+static struct config_item_type iio_triggers_item_type = {
+	.ct_owner	= THIS_MODULE,
+	.ct_item_ops	= &iio_trigger_item_ops,
+	.ct_attrs	= iio_trigger_item_attrs,
+};
+
+static struct config_item_type iio_triggers_root_type = {
+	.ct_owner	= THIS_MODULE,
+	.ct_group_ops	= &iio_triggers_group_ops,
+};
+
+static struct config_group iio_triggers_group = {
+	.cg_item = {
+		.ci_namebuf = "triggers",
+		.ci_type = &iio_triggers_root_type,
+	},
+};
+
+static struct config_group *iio_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_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@xxxxxxxxx>");
+MODULE_DESCRIPTION("Industrial I/O configfs support");
diff --git a/include/linux/iio/iio_configfs_trigger.h b/include/linux/iio/iio_configfs_trigger.h
new file mode 100644
index 0000000..e7b5777
--- /dev/null
+++ b/include/linux/iio/iio_configfs_trigger.h
@@ -0,0 +1,48 @@
+#ifndef __IIO_CONFIGFS_TRIGGER
+#define __IIO_CONFIGFS_TRIGGER
+
+#define IIO_TRIGGER_TYPE_NONE		0
+
+struct iio_configfs_trigger_info {
+	const char *name;
+	unsigned int type;
+	unsigned int active;
+	struct iio_trigger *trigger;
+	struct iio_configfs_ops *configfs_ops;
+};
+
+struct iio_configfs_ops {
+	int (*get_freq)(struct iio_configfs_trigger_info* );
+	int (*set_freq)(struct iio_configfs_trigger_info *, unsigned long);
+	int (*probe)(struct iio_configfs_trigger_info* );
+	int (*remove)(struct iio_configfs_trigger_info* );
+};
+
+static 
+inline int iio_none_get_freq(struct iio_configfs_trigger_info *trigger_info)
+{ 
+	return 0; 
+}
+
+static 
+inline int iio_none_set_freq(struct iio_configfs_trigger_info *trigger_info,
+			     unsigned long f)
+{
+	return 0; 
+}
+
+static
+inline int iio_none_probe(struct iio_configfs_trigger_info *trigger_info)
+{
+	return 0; 
+}
+
+static 
+inline int iio_none_remove(struct iio_configfs_trigger_info *trigger_info)
+{
+	return 0; 
+}
+
+extern struct iio_configfs_ops iio_hrtimer_ops;
+
+#endif /* __IIO_CONFIGFS_TRIGGER */
-- 
1.9.1

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