iio: core: wrap iio device & buffer into struct for character devices

In order to keep backwards compatibility with the current chardev
mechanism, and in order to add support for multiple buffers per IIO device,
we need to pass both the IIO device & IIO buffer to the chardev.

This is particularly needed for the iio_buffer_read_outer() function, where
we need to pass another buffer object than 'indio_dev->buffer'.

Since we'll also open some chardevs via anon inodes, we can pass extra
buffers in that function by assigning another object to the
iio_dev_buffer_pair object.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-17-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
index 731f5170d5b917d3fbc87e5c927c0faeb46abc61..87868fff7d37da199d2ac59e71ea316ed895d8c9 100644 (file)
--- a/drivers/iio/iio_core.h
+++ b/drivers/iio/iio_core.h
@@ -18,6 +18,11 @@ struct iio_dev;
 
 extern struct device_type iio_device_type;
 
+struct iio_dev_buffer_pair {
+       struct iio_dev          *indio_dev;
+       struct iio_buffer       *buffer;
+};
+
 #define IIO_IOCTL_UNHANDLED    1
 struct iio_ioctl_handler {
        struct list_head entry;

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index ea91f9578deef0c50ae73a0307e67fece43871ff..232a60fe57d25f9a93b16e4a66c6e850d02f07fb 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -104,8 +104,9 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
 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_dev_buffer_pair *ib = filp->private_data;
+       struct iio_buffer *rb = ib->buffer;
+       struct iio_dev *indio_dev = ib->indio_dev;
        DEFINE_WAIT_FUNC(wait, woken_wake_function);
        size_t datum_size;
        size_t to_wait;
@@ -170,8 +171,9 @@ ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
 __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_dev_buffer_pair *ib = filp->private_data;
+       struct iio_buffer *rb = ib->buffer;
+       struct iio_dev *indio_dev = ib->indio_dev;
 
        if (!indio_dev->info || rb == NULL)
                return 0;

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index b8b149ccecefaabe9921499e35508c21bf25d726..b96acfe13e924e03259d95b52aa3fcb69b40eb45 100644 (file)
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1705,13 +1705,24 @@ 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);
+       struct iio_dev_buffer_pair *ib;
 
        if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
                return -EBUSY;
 
        iio_device_get(indio_dev);
 
-       filp->private_data = indio_dev;
+       ib = kmalloc(sizeof(*ib), GFP_KERNEL);
+       if (!ib) {
+               iio_device_put(indio_dev);
+               clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
+               return -ENOMEM;
+       }
+
+       ib->indio_dev = indio_dev;
+       ib->buffer = indio_dev->buffer;
+
+       filp->private_data = ib;
 
        return 0;
 }
@@ -1725,8 +1736,10 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
  */
 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);
+       kfree(ib);
        clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
        iio_device_put(indio_dev);
 
@@ -1748,7 +1761,8 @@ void iio_device_ioctl_handler_unregister(struct iio_ioctl_handler *h)
 
 static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
-       struct iio_dev *indio_dev = filp->private_data;
+       struct iio_dev_buffer_pair *ib = filp->private_data;
+       struct iio_dev *indio_dev = ib->indio_dev;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_ioctl_handler *h;
        int ret = -ENODEV;