This patch moves the chardev creation into industrialio-buffer.c &
industrialio-event.c. The move has to be in a single step (which makes the
patch a bit big), in order to pass the reference of the chardev to
'indio_dev->chrdev'.

For structure purposes, industrialio-core.c should be the place where
cdev_device_add()/device_add() gets called, and the deletion function as
well.

What happens after this patch is:
- 'indio_dev->chrdev' is converted to a pointer
- if there is an IIO buffer, iio_device_buffer_attach_chrdev() will attach
  it's chardev to 'indio_chrdev'
- if it doesn't, the event interface will attach a reference to it's
  chardev (if it is instantiated) via iio_device_event_attach_chrdev()

That way, the control of the 'legacy' chardev is still visible in
'industrialio-core.c'. So, each logic file (for buffers & events) shouldn't
hide things too much away from the core file.

Signed-off-by: Alexandru Ardelean <alexandru.ardel...@analog.com>
---
 drivers/iio/iio_core.h            | 16 ++---
 drivers/iio/industrialio-buffer.c | 90 +++++++++++++++++++++++++---
 drivers/iio/industrialio-core.c   | 99 +++----------------------------
 drivers/iio/industrialio-event.c  | 98 +++++++++++++++++++++++++++++-
 include/linux/iio/buffer_impl.h   |  7 +++
 include/linux/iio/iio.h           |  6 +-
 6 files changed, 204 insertions(+), 112 deletions(-)

diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
index 39ec0344fb68..a527a66be9e5 100644
--- a/drivers/iio/iio_core.h
+++ b/drivers/iio/iio_core.h
@@ -40,17 +40,14 @@ ssize_t iio_format_value(char *buf, unsigned int type, int 
size, int *vals);
 #ifdef CONFIG_IIO_BUFFER
 struct poll_table_struct;
 
-__poll_t iio_buffer_poll(struct file *filp,
-                            struct poll_table_struct *wait);
-ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
-                             size_t n, loff_t *f_ps);
+long iio_device_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
+                           unsigned int cmd, unsigned long arg);
+
+void iio_device_buffer_attach_chrdev(struct iio_dev *indio_dev);
 
 int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev);
 void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev);
 
-#define iio_buffer_poll_addr (&iio_buffer_poll)
-#define iio_buffer_read_outer_addr (&iio_buffer_read_outer)
-
 void iio_device_buffers_put(struct iio_dev *indio_dev);
 
 void iio_disable_all_buffers(struct iio_dev *indio_dev);
@@ -58,8 +55,7 @@ void iio_buffer_wakeup_poll(struct iio_dev *indio_dev);
 
 #else
 
-#define iio_buffer_poll_addr NULL
-#define iio_buffer_read_outer_addr NULL
+static inline void iio_device_buffer_attach_chrdev(struct iio_dev *indio_dev) 
{}
 
 static inline int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
 {
@@ -77,8 +73,8 @@ static inline void iio_buffer_wakeup_poll(struct iio_dev 
*indio_dev) {}
 
 int iio_device_register_eventset(struct iio_dev *indio_dev);
 void iio_device_unregister_eventset(struct iio_dev *indio_dev);
+void iio_device_event_attach_chrdev(struct iio_dev *indio_dev);
 void iio_device_wakeup_eventset(struct iio_dev *indio_dev);
-int iio_event_getfd(struct iio_dev *indio_dev);
 
 struct iio_event_interface;
 bool iio_event_enabled(const struct iio_event_interface *ev_int);
diff --git a/drivers/iio/industrialio-buffer.c 
b/drivers/iio/industrialio-buffer.c
index 93f187455461..1400688f5e42 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -99,11 +99,11 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev, 
struct iio_buffer *buf,
  * Return: negative values corresponding to error codes or ret != 0
  *        for ending the reading activity
  **/
-ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
-                             size_t n, loff_t *f_ps)
+static ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
+                                    size_t n, loff_t *f_ps)
 {
-       struct iio_dev *indio_dev = filp->private_data;
-       struct iio_buffer *rb = indio_dev->buffer;
+       struct iio_buffer *rb = filp->private_data;
+       struct iio_dev *indio_dev = rb->indio_dev;
        DEFINE_WAIT_FUNC(wait, woken_wake_function);
        size_t datum_size;
        size_t to_wait;
@@ -165,11 +165,11 @@ ssize_t iio_buffer_read_outer(struct file *filp, char 
__user *buf,
  * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
  *        or 0 for other cases
  */
-__poll_t iio_buffer_poll(struct file *filp,
+static __poll_t iio_buffer_poll(struct file *filp,
                             struct poll_table_struct *wait)
 {
-       struct iio_dev *indio_dev = filp->private_data;
-       struct iio_buffer *rb = indio_dev->buffer;
+       struct iio_buffer *rb = filp->private_data;
+       struct iio_dev *indio_dev = rb->indio_dev;
 
        if (!indio_dev->info || rb == NULL)
                return 0;
@@ -180,6 +180,48 @@ __poll_t iio_buffer_poll(struct file *filp,
        return 0;
 }
 
+/**
+ * iio_buffer_chrdev_open() - chrdev file open for buffer access
+ * @inode:     Inode structure for identifying the device in the file system
+ * @filp:      File structure for iio device used to keep and later access
+ *             private data
+ *
+ * Return: 0 on success or -EBUSY if the device is already opened
+ **/
+static int iio_buffer_chrdev_open(struct inode *inode, struct file *filp)
+{
+       struct iio_buffer *buffer = container_of(inode->i_cdev,
+                                                struct iio_buffer, chrdev);
+
+       if (test_and_set_bit(IIO_BUSY_BIT_POS, &buffer->file_ops_flags))
+               return -EBUSY;
+
+       iio_buffer_get(buffer);
+
+       filp->private_data = buffer;
+
+       return 0;
+}
+
+/**
+ * iio_buffer_chrdev_release() - chrdev file close for buffer access
+ * @inode:     Inode structure pointer for the char device
+ * @filp:      File structure pointer for the char device
+ *
+ * Return: 0 for successful release
+ */
+static int iio_buffer_chrdev_release(struct inode *inode, struct file *filp)
+{
+       struct iio_buffer *buffer = container_of(inode->i_cdev,
+                                                struct iio_buffer, chrdev);
+
+       clear_bit(IIO_BUSY_BIT_POS, &buffer->file_ops_flags);
+
+       iio_buffer_put(buffer);
+
+       return 0;
+}
+
 /**
  * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
  * @indio_dev: The IIO device
@@ -1149,6 +1191,17 @@ void iio_disable_all_buffers(struct iio_dev *indio_dev)
        iio_buffer_deactivate_all(indio_dev);
 }
 
+static long iio_buffer_ioctl(struct file *filep, unsigned int cmd,
+                            unsigned long arg)
+{
+       struct iio_buffer *buffer = filep->private_data;
+
+       if (!buffer || !buffer->access)
+               return -ENODEV;
+
+       return iio_device_event_ioctl(buffer->indio_dev, filep, cmd, arg);
+}
+
 static ssize_t iio_buffer_store_enable(struct device *dev,
                                       struct device_attribute *attr,
                                       const char *buf,
@@ -1371,6 +1424,29 @@ void iio_buffer_free_sysfs_and_mask(struct iio_dev 
*indio_dev)
        iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
 }
 
+static const struct file_operations iio_buffer_fileops = {
+       .read = iio_buffer_read_outer,
+       .release = iio_buffer_chrdev_release,
+       .open = iio_buffer_chrdev_open,
+       .poll = iio_buffer_poll,
+       .owner = THIS_MODULE,
+       .llseek = noop_llseek,
+       .unlocked_ioctl = iio_buffer_ioctl,
+       .compat_ioctl = compat_ptr_ioctl,
+};
+
+void iio_device_buffer_attach_chrdev(struct iio_dev *indio_dev)
+{
+       struct iio_buffer *buffer = indio_dev->buffer;
+
+       if (!buffer)
+               return;
+
+       cdev_init(&buffer->chrdev, &iio_buffer_fileops);
+
+       indio_dev->chrdev = &buffer->chrdev;
+}
+
 void iio_device_buffers_put(struct iio_dev *indio_dev)
 {
        struct iio_buffer *buffer = indio_dev->buffer;
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index d74279efeca4..32e045c7f0c1 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1587,79 +1587,6 @@ struct iio_dev *devm_iio_device_alloc(struct device 
*dev, int sizeof_priv)
 }
 EXPORT_SYMBOL_GPL(devm_iio_device_alloc);
 
-/**
- * iio_chrdev_open() - chrdev file open for buffer access and ioctls
- * @inode:     Inode structure for identifying the device in the file system
- * @filp:      File structure for iio device used to keep and later access
- *             private data
- *
- * Return: 0 on success or -EBUSY if the device is already opened
- **/
-static int iio_chrdev_open(struct inode *inode, struct file *filp)
-{
-       struct iio_dev *indio_dev = container_of(inode->i_cdev,
-                                               struct iio_dev, chrdev);
-
-       if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
-               return -EBUSY;
-
-       iio_device_get(indio_dev);
-
-       filp->private_data = indio_dev;
-
-       return 0;
-}
-
-/**
- * iio_chrdev_release() - chrdev file close buffer access and ioctls
- * @inode:     Inode structure pointer for the char device
- * @filp:      File structure pointer for the char device
- *
- * Return: 0 for successful release
- */
-static int iio_chrdev_release(struct inode *inode, struct file *filp)
-{
-       struct iio_dev *indio_dev = container_of(inode->i_cdev,
-                                               struct iio_dev, chrdev);
-       clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
-       iio_device_put(indio_dev);
-
-       return 0;
-}
-
-/* Somewhat of a cross file organization violation - ioctls here are actually
- * event related */
-static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
-{
-       struct iio_dev *indio_dev = filp->private_data;
-       int __user *ip = (int __user *)arg;
-       int fd;
-
-       if (!indio_dev->info)
-               return -ENODEV;
-
-       if (cmd == IIO_GET_EVENT_FD_IOCTL) {
-               fd = iio_event_getfd(indio_dev);
-               if (fd < 0)
-                       return fd;
-               if (copy_to_user(ip, &fd, sizeof(fd)))
-                       return -EFAULT;
-               return 0;
-       }
-       return -EINVAL;
-}
-
-static const struct file_operations iio_buffer_fileops = {
-       .read = iio_buffer_read_outer_addr,
-       .release = iio_chrdev_release,
-       .open = iio_chrdev_open,
-       .poll = iio_buffer_poll_addr,
-       .owner = THIS_MODULE,
-       .llseek = noop_llseek,
-       .unlocked_ioctl = iio_ioctl,
-       .compat_ioctl = compat_ptr_ioctl,
-};
-
 static int iio_check_unique_scan_index(struct iio_dev *indio_dev)
 {
        int i, j;
@@ -1708,15 +1635,6 @@ static void iio_device_free_chrdev_id(struct device *dev)
 
 static const struct iio_buffer_setup_ops noop_ring_setup_ops;
 
-static const struct file_operations iio_event_fileops = {
-       .owner = THIS_MODULE,
-       .llseek = noop_llseek,
-       .unlocked_ioctl = iio_ioctl,
-       .compat_ioctl = compat_ptr_ioctl,
-       .open = iio_chrdev_open,
-       .release = iio_chrdev_release,
-};
-
 int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
 {
        int ret;
@@ -1764,20 +1682,21 @@ int __iio_device_register(struct iio_dev *indio_dev, 
struct module *this_mod)
                indio_dev->setup_ops == NULL)
                indio_dev->setup_ops = &noop_ring_setup_ops;
 
-       if (indio_dev->buffer)
-               cdev_init(&indio_dev->chrdev, &iio_buffer_fileops);
-       else if (indio_dev->event_interface)
-               cdev_init(&indio_dev->chrdev, &iio_event_fileops);
+       iio_device_buffer_attach_chrdev(indio_dev);
+
+       /* No chrdev attached from buffer, we go with event-only chrdev */
+       if (!indio_dev->chrdev)
+               iio_device_event_attach_chrdev(indio_dev);
 
-       if (indio_dev->buffer || indio_dev->event_interface) {
-               indio_dev->chrdev.owner = this_mod;
+       if (indio_dev->chrdev) {
+               indio_dev->chrdev->owner = this_mod;
 
                ret = iio_device_alloc_chrdev_id(&indio_dev->dev);
                if (ret)
                        goto error_unreg_eventset;
        }
 
-       ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
+       ret = cdev_device_add(indio_dev->chrdev, &indio_dev->dev);
        if (ret)
                goto error_free_chrdev_id;
 
@@ -1803,7 +1722,7 @@ EXPORT_SYMBOL(__iio_device_register);
  **/
 void iio_device_unregister(struct iio_dev *indio_dev)
 {
-       cdev_device_del(&indio_dev->chrdev, &indio_dev->dev);
+       cdev_device_del(indio_dev->chrdev, &indio_dev->dev);
        iio_device_free_chrdev_id(&indio_dev->dev);
 
        mutex_lock(&indio_dev->info_exist_lock);
diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
index 5b17c92d3b50..0674b2117c98 100644
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -30,6 +30,8 @@
  * @flags:             file operations related flags including busy flag.
  * @group:             event interface sysfs attribute group
  * @read_lock:         lock to protect kfifo read operations
+ * @chrdev:            associated chardev for this event
+ * @indio_dev:         IIO device to which this event interface belongs to
  */
 struct iio_event_interface {
        wait_queue_head_t       wait;
@@ -39,6 +41,9 @@ struct iio_event_interface {
        unsigned long           flags;
        struct attribute_group  group;
        struct mutex            read_lock;
+
+       struct cdev             chrdev;
+       struct iio_dev          *indio_dev;
 };
 
 bool iio_event_enabled(const struct iio_event_interface *ev_int)
@@ -182,7 +187,7 @@ static const struct file_operations 
iio_event_chrdev_fileops = {
        .llseek = noop_llseek,
 };
 
-int iio_event_getfd(struct iio_dev *indio_dev)
+static int iio_event_getfd(struct iio_dev *indio_dev)
 {
        struct iio_event_interface *ev_int = indio_dev->event_interface;
        int fd;
@@ -215,6 +220,97 @@ int iio_event_getfd(struct iio_dev *indio_dev)
        return fd;
 }
 
+/**
+ * iio_chrdev_open() - chrdev file open for event ioctls
+ * @inode:     Inode structure for identifying the device in the file system
+ * @filp:      File structure for iio device used to keep and later access
+ *             private data
+ *
+ * Return: 0 on success or -EBUSY if the device is already opened
+ **/
+static int iio_chrdev_open(struct inode *inode, struct file *filp)
+{
+       struct iio_event_interface *ev =
+               container_of(inode->i_cdev, struct iio_event_interface, chrdev);
+
+       if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev->flags))
+               return -EBUSY;
+
+       iio_device_get(ev->indio_dev);
+
+       filp->private_data = ev;
+
+       return 0;
+}
+
+/**
+ * iio_chrdev_release() - chrdev file close for event ioctls
+ * @inode:     Inode structure pointer for the char device
+ * @filp:      File structure pointer for the char device
+ *
+ * Return: 0 for successful release
+ */
+static int iio_chrdev_release(struct inode *inode, struct file *filp)
+{
+       struct iio_event_interface *ev =
+               container_of(inode->i_cdev, struct iio_event_interface, chrdev);
+
+       clear_bit(IIO_BUSY_BIT_POS, &ev->flags);
+       iio_device_put(ev->indio_dev);
+
+       return 0;
+}
+
+long iio_device_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
+                           unsigned int cmd, unsigned long arg)
+{
+       int __user *ip = (int __user *)arg;
+       int fd;
+
+       if (!indio_dev->info)
+               return -ENODEV;
+
+       if (cmd == IIO_GET_EVENT_FD_IOCTL) {
+               fd = iio_event_getfd(indio_dev);
+               if (fd < 0)
+                       return fd;
+               if (copy_to_user(ip, &fd, sizeof(fd)))
+                       return -EFAULT;
+               return 0;
+       }
+       return -EINVAL;
+}
+
+static long iio_event_ioctl_wrapper(struct file *filp, unsigned int cmd,
+                                   unsigned long arg)
+{
+       struct iio_event_interface *ev = filp->private_data;
+
+       return iio_device_event_ioctl(ev->indio_dev, filp, cmd, arg);
+}
+
+static const struct file_operations iio_event_fileops = {
+       .release = iio_chrdev_release,
+       .open = iio_chrdev_open,
+       .owner = THIS_MODULE,
+       .llseek = noop_llseek,
+       .unlocked_ioctl = iio_event_ioctl_wrapper,
+       .compat_ioctl = compat_ptr_ioctl,
+};
+
+void iio_device_event_attach_chrdev(struct iio_dev *indio_dev)
+{
+       struct iio_event_interface *ev = indio_dev->event_interface;
+
+       if (!ev)
+               return;
+
+       cdev_init(&ev->chrdev, &iio_event_fileops);
+
+       ev->indio_dev = indio_dev;
+       indio_dev->chrdev = &ev->chrdev;
+}
+
 static const char * const iio_ev_type_text[] = {
        [IIO_EV_TYPE_THRESH] = "thresh",
        [IIO_EV_TYPE_MAG] = "mag",
diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
index 67d73d465e02..46fc977deae3 100644
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _IIO_BUFFER_GENERIC_IMPL_H_
 #define _IIO_BUFFER_GENERIC_IMPL_H_
+#include <linux/cdev.h>
 #include <linux/sysfs.h>
 #include <linux/kref.h>
 
@@ -72,6 +73,12 @@ struct iio_buffer {
        /** @indio_dev: IIO device to which this buffer belongs to. */
        struct iio_dev *indio_dev;
 
+       /** @chrdev: associated character device. */
+       struct cdev chrdev;
+
+       /** @file_ops_flags: file ops related flags including busy flag. */
+       unsigned long file_ops_flags;
+
        /** @length: Number of datums in buffer. */
        unsigned int length;
 
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 5f9f439a4f01..52992be44e9e 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -516,10 +516,9 @@ struct iio_buffer_setup_ops {
  * @info_exist_lock:   [INTERN] lock to prevent use during removal
  * @setup_ops:         [DRIVER] callbacks to call before and after buffer
  *                     enable/disable
- * @chrdev:            [INTERN] associated character device
+ * @chrdev:            [INTERN] reference to associated character device
  * @groups:            [INTERN] attribute groups
  * @groupcounter:      [INTERN] index of next attribute group
- * @flags:             [INTERN] file ops related flags including busy flag.
  * @debugfs_dentry:    [INTERN] device specific debugfs dentry.
  * @cached_reg_addr:   [INTERN] cached register address for debugfs reads.
  */
@@ -559,12 +558,11 @@ struct iio_dev {
        clockid_t                       clock_id;
        struct mutex                    info_exist_lock;
        const struct iio_buffer_setup_ops       *setup_ops;
-       struct cdev                     chrdev;
+       struct cdev                     *chrdev;
 #define IIO_MAX_GROUPS 6
        const struct attribute_group    *groups[IIO_MAX_GROUPS + 1];
        int                             groupcounter;
 
-       unsigned long                   flags;
 #if defined(CONFIG_DEBUG_FS)
        struct dentry                   *debugfs_dentry;
        unsigned                        cached_reg_addr;
-- 
2.17.1

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