[PATCH v2 3/5] iio: buffer: move iio buffer chrdev in industrialio-buffer.c

From: Alexandru Ardelean
Date: Fri Apr 10 2020 - 08:39:25 EST

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This change makes the first jump to move the buffer chardev from indio_dev
to the buffer attached to indio_dev (i.e. indio_dev->buffer).

This requires that some functions that are shared between
'industrialio-core.c' & industrialio-buffer.c be re-shuffled.
The 'iio_buffer_fileops' is now moved to 'industrialio-buffer.c'. It's also
more appropriate to have it here, but the old 'legacy' iio_ioctl() must be
passed to it.

What happens now is:
* if IS_ENABLED(CONFIG_IIO_BUFFER) and 'indio_dev->buffer != NULL' the
indio_dev->buffer->chrdev will be initialized (as the old legacy style
chardev)
* if -ENOTSUPP is returned for either of the conditions above (not being
met), the chardev will be created directly via 'indio_dev->chrdev', same
as before; a new field is required now 'indio_dev->chrdev_initialized' to
mark it true, so that 'indio_dev->chrdev' gets deleted if initialized;

'indio_dev->chrdev_initialized' is of type 'int', because recently
checkpatch complains that 'bool' types on structs can cause alignment
issues.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
---
drivers/iio/iio_core.h | 25 ++++---
drivers/iio/industrialio-buffer.c | 119 ++++++++++++++++++++++++++++--
drivers/iio/industrialio-core.c | 59 ++++++++-------
include/linux/iio/buffer_impl.h | 7 ++
include/linux/iio/iio.h | 2 +
5 files changed, 170 insertions(+), 42 deletions(-)

diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
index fd9a5f1d5e51..4bdadeac2710 100644
--- a/drivers/iio/iio_core.h
+++ b/drivers/iio/iio_core.h
@@ -40,24 +40,31 @@ 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);
+
+int iio_device_buffers_init(struct iio_dev *indio_dev, struct module *this_mod);
+void iio_device_buffers_uninit(struct iio_dev *indio_dev);
+
+void iio_device_buffers_put(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_disable_all_buffers(struct iio_dev *indio_dev);
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 int iio_device_buffers_init(struct iio_dev *indio_dev,
+ struct module *this_mod)
+{
+ return -ENOTSUPP;
+}
+
+static inline void iio_device_buffers_uninit(struct iio_dev *indio_dev) {}
+
+static inline void iio_device_buffers_put(struct iio_dev *indio_dev) {}

static inline int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
{
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index f9ffc7762f6c..4b5c3baadaab 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
@@ -1121,6 +1163,14 @@ void iio_disable_all_buffers(struct iio_dev *indio_dev)
iio_buffer_deactivate_all(indio_dev);
}

+long iio_buffer_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
+{
+ struct iio_buffer *buffer = filep->private_data;
+ struct iio_dev *indio_dev = buffer->indio_dev;
+
+ return iio_device_event_ioctl(indio_dev, filep, cmd, arg);
+}
+
static ssize_t iio_buffer_store_enable(struct device *dev,
struct device_attribute *attr,
const char *buf,
@@ -1356,6 +1406,61 @@ void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
iio_free_chan_devattr_list(&indio_dev->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,
+};
+
+int iio_device_buffers_init(struct iio_dev *indio_dev, struct module *this_mod)
+{
+ struct iio_buffer *buffer = indio_dev->buffer;
+ int ret;
+
+ if (!buffer)
+ return -ENOTSUPP;
+
+ cdev_init(&buffer->chrdev, &iio_buffer_fileops);
+
+ buffer->chrdev.owner = this_mod;
+
+ ret = cdev_device_add(&buffer->chrdev, &indio_dev->dev);
+ if (ret)
+ return ret;
+
+ iio_device_get(indio_dev);
+ iio_buffer_get(buffer);
+
+ return 0;
+}
+
+void iio_device_buffers_put(struct iio_dev *indio_dev)
+{
+ struct iio_buffer *buffer = indio_dev->buffer;
+
+ if (!buffer)
+ return;
+
+ iio_buffer_put(buffer);
+}
+
+void iio_device_buffers_uninit(struct iio_dev *indio_dev)
+{
+ struct iio_buffer *buffer = indio_dev->buffer;
+
+ if (!buffer)
+ return;
+
+ cdev_device_del(&buffer->chrdev, &indio_dev->dev);
+ iio_buffer_put(buffer);
+ iio_device_put(indio_dev);
+}
+
/**
* iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
* @indio_dev: the iio device
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index c8c074602709..2158aeab0bd2 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1475,7 +1475,7 @@ static void iio_dev_release(struct device *device)
iio_device_unregister_eventset(indio_dev);
iio_device_unregister_sysfs(indio_dev);

- iio_buffer_put(indio_dev->buffer);
+ iio_device_buffers_put(indio_dev);

ida_simple_remove(&iio_ida, indio_dev->id);
kfree(indio_dev);
@@ -1610,7 +1610,7 @@ void devm_iio_device_free(struct device *dev, struct iio_dev *iio_dev)
EXPORT_SYMBOL_GPL(devm_iio_device_free);

/**
- * iio_chrdev_open() - chrdev file open for buffer access and ioctls
+ * 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
@@ -1633,7 +1633,7 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
}

/**
- * iio_chrdev_release() - chrdev file close buffer access and ioctls
+ * 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
*
@@ -1649,11 +1649,9 @@ static int iio_chrdev_release(struct inode *inode, struct file *filp)
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)
+long iio_device_event_ioctl(struct iio_dev *indio_dev, 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;

@@ -1671,16 +1669,15 @@ static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
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,
-};
+/* Somewhat of a cross file organization violation - ioctls here are actually
+ * event related */
+static long iio_event_ioctl_wrapper(struct file *filp, unsigned int cmd,
+ unsigned long arg)
+{
+ struct iio_dev *indio_dev = filp->private_data;
+
+ return iio_device_event_ioctl(indio_dev, filp, cmd, arg);
+}

static int iio_check_unique_scan_index(struct iio_dev *indio_dev)
{
@@ -1712,7 +1709,7 @@ static const struct file_operations iio_event_fileops = {
.open = iio_chrdev_open,
.owner = THIS_MODULE,
.llseek = noop_llseek,
- .unlocked_ioctl = iio_ioctl,
+ .unlocked_ioctl = iio_event_ioctl_wrapper,
.compat_ioctl = compat_ptr_ioctl,
};

@@ -1766,16 +1763,21 @@ 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
+ ret = iio_device_buffers_init(indio_dev, this_mod);
+ if (ret) {
+ if (ret != -ENOTSUPP)
+ goto error_unreg_eventset;
+
cdev_init(&indio_dev->chrdev, &iio_event_fileops);

- indio_dev->chrdev.owner = this_mod;
+ indio_dev->chrdev.owner = this_mod;

- ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
- if (ret < 0)
- goto error_unreg_eventset;
+ ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
+ if (ret < 0)
+ goto error_unreg_eventset;
+
+ indio_dev->chrdev_initialized = true;
+ }

return 0;

@@ -1797,7 +1799,12 @@ EXPORT_SYMBOL(__iio_device_register);
**/
void iio_device_unregister(struct iio_dev *indio_dev)
{
- cdev_device_del(&indio_dev->chrdev, &indio_dev->dev);
+ if (indio_dev->chrdev_initialized)
+ cdev_device_del(&indio_dev->chrdev, &indio_dev->dev);
+
+ indio_dev->chrdev_initialized = false;
+
+ iio_device_buffers_uninit(indio_dev);

mutex_lock(&indio_dev->info_exist_lock);

diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
index 8fb92250a190..b4a55c3f556b 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 e975020abaa6..e93497f483f7 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -517,6 +517,7 @@ struct iio_buffer_setup_ops {
* @setup_ops: [DRIVER] callbacks to call before and after buffer
* enable/disable
* @chrdev: [INTERN] associated character device
+ * @chrdev_initialized: [INTERN] true if @chrdev device has been initialized
* @groups: [INTERN] attribute groups
* @groupcounter: [INTERN] index of next attribute group
* @flags: [INTERN] file ops related flags including busy flag.
@@ -560,6 +561,7 @@ struct iio_dev {
struct mutex info_exist_lock;
const struct iio_buffer_setup_ops *setup_ops;
struct cdev chrdev;
+ int chrdev_initialized;
#define IIO_MAX_GROUPS 6
const struct attribute_group *groups[IIO_MAX_GROUPS + 1];
int groupcounter;
--
2.17.1

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