With this change, an ioctl() call is added to open a character device for a
buffer.
The ioctl() will not work for the first buffer, as that buffer is already
opened/reserved for the IIO device's character device.
This is also to preserve backwards compatibility.
For any other extra buffer (after the first buffer) this ioctl() will be
required.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
---
drivers/iio/industrialio-buffer.c | 111 ++++++++++++++++++++++++++++++
drivers/iio/industrialio-core.c | 8 +++
include/linux/iio/buffer_impl.h | 5 ++
include/linux/iio/iio-opaque.h | 2 +
include/uapi/linux/iio/buffer.h | 16 +++++
5 files changed, 142 insertions(+)
create mode 100644 include/uapi/linux/iio/buffer.h
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index daa68822cea7..77f02870cd18 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -9,6 +9,7 @@
* - Better memory allocation techniques?
* - Alternative access techniques?
*/
+#include <linux/anon_inodes.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/device.h>
@@ -1399,6 +1400,99 @@ static void iio_sysfs_del_attrs(struct kobject *kobj, struct attribute **ptr)
sysfs_remove_file(kobj, ptr[i]);
}
+static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep)
+{
+ struct iio_dev_buffer_pair *ib = filep->private_data;
+ struct iio_dev *indio_dev = ib->indio_dev;
+ struct iio_buffer *buffer = ib->buffer;
+
+ clear_bit(IIO_BUSY_BIT_POS, &buffer->flags);
+ iio_device_put(indio_dev);
+ kfree(ib);
+
+ return 0;
+}
+
+static const struct file_operations iio_buffer_chrdev_fileops = {
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .read = iio_buffer_read_outer_addr,
+ .poll = iio_buffer_poll_addr,
+ .compat_ioctl = compat_ptr_ioctl,
+ .release = iio_buffer_chrdev_release,
+};
+
+static long iio_device_buffer_getfd(struct iio_dev *indio_dev, unsigned long arg)
+{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+ int __user *ival = (int __user *)arg;
+ char buf_name[sizeof("iio:buffer:xxx")];
+ struct iio_dev_buffer_pair *ib;
+ struct iio_buffer *buffer;
+ int fd, idx;
+
+ if (copy_from_user(&idx, ival, sizeof(idx)))
+ return -EFAULT;
+
+ if (idx >= iio_dev_opaque->attached_buffers_cnt)
+ return -ENOENT;
+
+ fd = mutex_lock_interruptible(&indio_dev->mlock);
+ if (fd)
+ return fd;
+
+ buffer = iio_dev_opaque->attached_buffers[idx];
+
+ if (test_and_set_bit(IIO_BUSY_BIT_POS, &buffer->flags)) {
+ fd = -EBUSY;
+ goto error_unlock;
+ }
+
+ iio_device_get(indio_dev);
+
+ ib = kzalloc(sizeof(*ib), GFP_KERNEL);
+ if (!ib) {
+ fd = -ENOMEM;
+ goto error_iio_dev_put;
+ }
+
+ ib->indio_dev = indio_dev;
+ ib->buffer = buffer;
+
+ fd = anon_inode_getfd(buf_name, &iio_buffer_chrdev_fileops,
+ ib, O_RDWR | O_CLOEXEC);
+ if (fd < 0)
+ goto error_free_ib;
+
+ if (copy_to_user(ival, &fd, sizeof(fd))) {
+ fd = -EFAULT;
+ goto error_free_ib;
+ }
+
+ mutex_unlock(&indio_dev->mlock);
+ return fd;
+
+error_free_ib:
+ kfree(ib);
+error_iio_dev_put:
+ iio_device_put(indio_dev);
+ clear_bit(IIO_BUSY_BIT_POS, &buffer->flags);
+error_unlock:
+ mutex_unlock(&indio_dev->mlock);
+ return fd;
+}
+
+static long iio_device_buffer_ioctl(struct iio_dev *indio_dev, struct file *filp,
+ unsigned int cmd, unsigned long arg)
+{
+ switch (cmd) {
+ case IIO_BUFFER_GET_FD_IOCTL:
+ return iio_device_buffer_getfd(indio_dev, arg);
+ default:
+ return IIO_IOCTL_UNHANDLED;
+ }
+}
+
static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
struct iio_dev *indio_dev,
unsigned int idx)
@@ -1549,8 +1643,21 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
if (ret)
goto error_remove_buffer_dir_link;
+ i = sizeof(*(iio_dev_opaque->buffer_ioctl_handler));
+ iio_dev_opaque->buffer_ioctl_handler = kzalloc(i, GFP_KERNEL);
+ if (!iio_dev_opaque->buffer_ioctl_handler) {
+ ret = -ENOMEM;
+ goto error_remove_scan_el_dir;
+ }
+
+ iio_dev_opaque->buffer_ioctl_handler->ioctl = iio_device_buffer_ioctl;
+ iio_device_ioctl_handler_register(indio_dev,
+ iio_dev_opaque->buffer_ioctl_handler);
+
return 0;
+error_remove_scan_el_dir:
+ sysfs_remove_link(&indio_dev->dev.kobj, "scan_elements");
error_remove_buffer_dir_link:
sysfs_remove_link(&indio_dev->dev.kobj, "buffer");
i = iio_dev_opaque->attached_buffers_cnt - 1;
@@ -1585,6 +1692,10 @@ void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
if (!buffer)
return;
+ iio_device_ioctl_handler_unregister(iio_dev_opaque->buffer_ioctl_handler);
+ kfree(iio_dev_opaque->buffer_ioctl_handler);
+ iio_dev_opaque->buffer_ioctl_handler = NULL;
+
sysfs_remove_link(&indio_dev->dev.kobj, "scan_elements");
sysfs_remove_link(&indio_dev->dev.kobj, "buffer");
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 9e7a76723f00..b4f7dd75bef5 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1685,6 +1685,9 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
ib->indio_dev = indio_dev;
ib->buffer = indio_dev->buffer;
+ if (indio_dev->buffer)
+ test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->buffer->flags);
+
filp->private_data = ib;
return 0;
@@ -1702,6 +1705,11 @@ static int iio_chrdev_release(struct inode *inode, struct file *filp)
struct iio_dev_buffer_pair *ib = filp->private_data;
struct iio_dev *indio_dev = container_of(inode->i_cdev,
struct iio_dev, chrdev);
+ struct iio_buffer *buffer = ib->buffer;
+
+ if (buffer)
+ clear_bit(IIO_BUSY_BIT_POS, &buffer->flags);
+
clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
iio_device_put(indio_dev);
kfree(ib);
diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
index e25d26a7f601..78da590b5607 100644
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -6,6 +6,8 @@
#ifdef CONFIG_IIO_BUFFER
+#include <uapi/linux/iio/buffer.h>
+
struct iio_dev;
struct iio_buffer;
@@ -75,6 +77,9 @@ struct iio_buffer {
/** @length: Number of datums in buffer. */
unsigned int length;
+ /** @flags: File ops flags including busy flag. */
+ unsigned long flags;
+
/** @bytes_per_datum: Size of individual datum including timestamp. */
size_t bytes_per_datum;
diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h
index 1db0ea09520e..d0429b13afa8 100644
--- a/include/linux/iio/iio-opaque.h
+++ b/include/linux/iio/iio-opaque.h
@@ -9,6 +9,7 @@
* @event_interface: event chrdevs associated with interrupt lines
* @attached_buffers: array of buffers statically attached by the driver
* @attached_buffers_cnt: number of buffers in the array of statically attached buffers
+ * @buffer_ioctl_handler: ioctl() handler for this IIO device's buffer interface
* @buffer_list: list of all buffers currently attached
* @channel_attr_list: keep track of automatically created channel
* attributes
@@ -24,6 +25,7 @@ struct iio_dev_opaque {
struct iio_event_interface *event_interface;
struct iio_buffer **attached_buffers;
unsigned int attached_buffers_cnt;
+ struct iio_ioctl_handler *buffer_ioctl_handler;
struct list_head buffer_list;
struct list_head channel_attr_list;
struct attribute_group chan_attr_group;
diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h
new file mode 100644
index 000000000000..3794eca78dad
--- /dev/null
+++ b/include/uapi/linux/iio/buffer.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* industrial I/O buffer definitions needed both in and out of kernel
+ *
+ * Copyright (c) 2020 Alexandru Ardelean
+ *
+ * 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 _UAPI_IIO_BUFFER_H_
+#define _UAPI_IIO_BUFFER_H_
+
+#define IIO_BUFFER_GET_FD_IOCTL _IOWR('i', 0xa0, int)
+
+#endif /* _UAPI_IIO_BUFFER_H_ */
--
2.17.1
