iio: Add reference counting for buffers

[karo-tx-linux.git] / drivers / iio / industrialio-buffer.c

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index e9f389b9da690b616b04587b9e91a6304ddefffb..36c39dcad850497c47da6e736dd76097568380ca 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -74,6 +74,7 @@ void iio_buffer_init(struct iio_buffer *buffer)
        INIT_LIST_HEAD(&buffer->demux_list);
        INIT_LIST_HEAD(&buffer->buffer_list);
        init_waitqueue_head(&buffer->pollq);
+       kref_init(&buffer->ref);
 }
 EXPORT_SYMBOL(iio_buffer_init);
 
@@ -454,6 +455,19 @@ static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
        return bytes;
 }
 
+static void iio_buffer_activate(struct iio_dev *indio_dev,
+       struct iio_buffer *buffer)
+{
+       iio_buffer_get(buffer);
+       list_add(&buffer->buffer_list, &indio_dev->buffer_list);
+}
+
+static void iio_buffer_deactivate(struct iio_buffer *buffer)
+{
+       list_del_init(&buffer->buffer_list);
+       iio_buffer_put(buffer);
+}
+
 void iio_disable_all_buffers(struct iio_dev *indio_dev)
 {
        struct iio_buffer *buffer, *_buffer;
@@ -466,7 +480,7 @@ void iio_disable_all_buffers(struct iio_dev *indio_dev)
 
        list_for_each_entry_safe(buffer, _buffer,
                        &indio_dev->buffer_list, buffer_list)
-               list_del_init(&buffer->buffer_list);
+               iio_buffer_deactivate(buffer);
 
        indio_dev->currentmode = INDIO_DIRECT_MODE;
        if (indio_dev->setup_ops->postdisable)
@@ -503,9 +517,9 @@ int iio_update_buffers(struct iio_dev *indio_dev,
                indio_dev->active_scan_mask = NULL;
 
        if (remove_buffer)
-               list_del_init(&remove_buffer->buffer_list);
+               iio_buffer_deactivate(remove_buffer);
        if (insert_buffer)
-               list_add(&insert_buffer->buffer_list, &indio_dev->buffer_list);
+               iio_buffer_activate(indio_dev, insert_buffer);
 
        /* If no buffers in list, we are done */
        if (list_empty(&indio_dev->buffer_list)) {
@@ -540,7 +554,7 @@ int iio_update_buffers(struct iio_dev *indio_dev,
                         * Roll back.
                         * Note can only occur when adding a buffer.
                         */
-                       list_del_init(&insert_buffer->buffer_list);
+                       iio_buffer_deactivate(insert_buffer);
                        if (old_mask) {
                                indio_dev->active_scan_mask = old_mask;
                                success = -EINVAL;
@@ -631,7 +645,7 @@ error_run_postdisable:
 error_remove_inserted:
 
        if (insert_buffer)
-               list_del_init(&insert_buffer->buffer_list);
+               iio_buffer_deactivate(insert_buffer);
        indio_dev->active_scan_mask = old_mask;
        kfree(compound_mask);
 error_ret:
@@ -952,3 +966,45 @@ error_clear_mux_table:
        return ret;
 }
 EXPORT_SYMBOL_GPL(iio_update_demux);
+
+/**
+ * iio_buffer_release() - Free a buffer's resources
+ * @ref: Pointer to the kref embedded in the iio_buffer struct
+ *
+ * This function is called when the last reference to the buffer has been
+ * dropped. It will typically free all resources allocated by the buffer. Do not
+ * call this function manually, always use iio_buffer_put() when done using a
+ * buffer.
+ */
+static void iio_buffer_release(struct kref *ref)
+{
+       struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
+
+       buffer->access->release(buffer);
+}
+
+/**
+ * iio_buffer_get() - Grab a reference to the buffer
+ * @buffer: The buffer to grab a reference for, may be NULL
+ *
+ * Returns the pointer to the buffer that was passed into the function.
+ */
+struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
+{
+       if (buffer)
+               kref_get(&buffer->ref);
+
+       return buffer;
+}
+EXPORT_SYMBOL_GPL(iio_buffer_get);
+
+/**
+ * iio_buffer_put() - Release the reference to the buffer
+ * @buffer: The buffer to release the reference for, may be NULL
+ */
+void iio_buffer_put(struct iio_buffer *buffer)
+{
+       if (buffer)
+               kref_put(&buffer->ref, iio_buffer_release);
+}
+EXPORT_SYMBOL_GPL(iio_buffer_put);