1 files changed, 290 insertions, 0 deletions
diff --git a/drivers/iio/buffer/kfifo_buf.c b/drivers/iio/buffer/kfifo_buf.c
new file mode 100644
index 000000000..35d8b4077
--- /dev/null
+++ b/drivers/iio/buffer/kfifo_buf.c
@@ -0,0 +1,290 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/workqueue.h>
+#include <linux/kfifo.h>
+#include <linux/mutex.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/iio/buffer_impl.h>
+#include <linux/sched.h>
+#include <linux/poll.h>
+
+struct iio_kfifo {
+	struct iio_buffer buffer;
+	struct kfifo kf;
+	struct mutex user_lock;
+	int update_needed;
+};
+
+#define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
+
+static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
+			size_t bytes_per_datum, unsigned int length)
+{
+	if ((length == 0) || (bytes_per_datum == 0))
+		return -EINVAL;
+
+	/*
+	 * Make sure we don't overflow an unsigned int after kfifo rounds up to
+	 * the next power of 2.
+	 */
+	if (roundup_pow_of_two(length) > UINT_MAX / bytes_per_datum)
+		return -EINVAL;
+
+	return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
+			     bytes_per_datum, GFP_KERNEL);
+}
+
+static int iio_request_update_kfifo(struct iio_buffer *r)
+{
+	int ret = 0;
+	struct iio_kfifo *buf = iio_to_kfifo(r);
+
+	mutex_lock(&buf->user_lock);
+	if (buf->update_needed) {
+		kfifo_free(&buf->kf);
+		ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
+				   buf->buffer.length);
+		if (ret >= 0)
+			buf->update_needed = false;
+	} else {
+		kfifo_reset_out(&buf->kf);
+	}
+	mutex_unlock(&buf->user_lock);
+
+	return ret;
+}
+
+static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	kf->update_needed = true;
+	return 0;
+}
+
+static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
+{
+	if (r->bytes_per_datum != bpd) {
+		r->bytes_per_datum = bpd;
+		iio_mark_update_needed_kfifo(r);
+	}
+	return 0;
+}
+
+static int iio_set_length_kfifo(struct iio_buffer *r, unsigned int length)
+{
+	/* Avoid an invalid state */
+	if (length < 2)
+		length = 2;
+	if (r->length != length) {
+		r->length = length;
+		iio_mark_update_needed_kfifo(r);
+	}
+	return 0;
+}
+
+static int iio_store_to_kfifo(struct iio_buffer *r,
+			      const void *data)
+{
+	int ret;
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	ret = kfifo_in(&kf->kf, data, 1);
+	if (ret != 1)
+		return -EBUSY;
+	return 0;
+}
+
+static int iio_read_kfifo(struct iio_buffer *r, size_t n, char __user *buf)
+{
+	int ret, copied;
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+
+	if (mutex_lock_interruptible(&kf->user_lock))
+		return -ERESTARTSYS;
+
+	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
+		ret = -EINVAL;
+	else
+		ret = kfifo_to_user(&kf->kf, buf, n, &copied);
+	mutex_unlock(&kf->user_lock);
+	if (ret < 0)
+		return ret;
+
+	return copied;
+}
+
+static size_t iio_kfifo_buf_data_available(struct iio_buffer *r)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	size_t samples;
+
+	mutex_lock(&kf->user_lock);
+	samples = kfifo_len(&kf->kf);
+	mutex_unlock(&kf->user_lock);
+
+	return samples;
+}
+
+static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(buffer);
+
+	mutex_destroy(&kf->user_lock);
+	kfifo_free(&kf->kf);
+	kfree(kf);
+}
+
+static size_t iio_kfifo_buf_space_available(struct iio_buffer *r)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	size_t avail;
+
+	mutex_lock(&kf->user_lock);
+	avail = kfifo_avail(&kf->kf);
+	mutex_unlock(&kf->user_lock);
+
+	return avail;
+}
+
+static int iio_kfifo_remove_from(struct iio_buffer *r, void *data)
+{
+	int ret;
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+
+	if (kfifo_size(&kf->kf) < 1)
+		return -EBUSY;
+
+	ret = kfifo_out(&kf->kf, data, 1);
+	if (ret != 1)
+		return -EBUSY;
+
+	wake_up_interruptible_poll(&r->pollq, EPOLLOUT | EPOLLWRNORM);
+
+	return 0;
+}
+
+static int iio_kfifo_write(struct iio_buffer *r, size_t n,
+	const char __user *buf)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	int ret, copied;
+
+	mutex_lock(&kf->user_lock);
+	if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
+		ret = -EINVAL;
+	else
+		ret = kfifo_from_user(&kf->kf, buf, n, &copied);
+	mutex_unlock(&kf->user_lock);
+	if (ret)
+		return ret;
+
+	return copied;
+}
+
+static const struct iio_buffer_access_funcs kfifo_access_funcs = {
+	.store_to = &iio_store_to_kfifo,
+	.read = &iio_read_kfifo,
+	.data_available = iio_kfifo_buf_data_available,
+	.remove_from = &iio_kfifo_remove_from,
+	.write = &iio_kfifo_write,
+	.space_available = &iio_kfifo_buf_space_available,
+	.request_update = &iio_request_update_kfifo,
+	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
+	.set_length = &iio_set_length_kfifo,
+	.release = &iio_kfifo_buffer_release,
+
+	.modes = INDIO_BUFFER_SOFTWARE | INDIO_BUFFER_TRIGGERED,
+};
+
+struct iio_buffer *iio_kfifo_allocate(void)
+{
+	struct iio_kfifo *kf;
+
+	kf = kzalloc(sizeof(*kf), GFP_KERNEL);
+	if (!kf)
+		return NULL;
+
+	kf->update_needed = true;
+	iio_buffer_init(&kf->buffer);
+	kf->buffer.access = &kfifo_access_funcs;
+	kf->buffer.length = 2;
+	mutex_init(&kf->user_lock);
+
+	return &kf->buffer;
+}
+EXPORT_SYMBOL(iio_kfifo_allocate);
+
+void iio_kfifo_free(struct iio_buffer *r)
+{
+	iio_buffer_put(r);
+}
+EXPORT_SYMBOL(iio_kfifo_free);
+
+static void devm_iio_kfifo_release(struct device *dev, void *res)
+{
+	iio_kfifo_free(*(struct iio_buffer **)res);
+}
+
+/**
+ * devm_iio_kfifo_allocate - Resource-managed iio_kfifo_allocate()
+ * @dev:		Device to allocate kfifo buffer for
+ *
+ * RETURNS:
+ * Pointer to allocated iio_buffer on success, NULL on failure.
+ */
+static struct iio_buffer *devm_iio_kfifo_allocate(struct device *dev)
+{
+	struct iio_buffer **ptr, *r;
+
+	ptr = devres_alloc(devm_iio_kfifo_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	r = iio_kfifo_allocate();
+	if (r) {
+		*ptr = r;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return r;
+}
+
+/**
+ * devm_iio_kfifo_buffer_setup_ext - Allocate a kfifo buffer & attach it to an IIO device
+ * @dev: Device object to which to attach the life-time of this kfifo buffer
+ * @indio_dev: The device the buffer should be attached to
+ * @setup_ops: The setup_ops required to configure the HW part of the buffer (optional)
+ * @buffer_attrs: Extra sysfs buffer attributes for this IIO buffer
+ *
+ * This function allocates a kfifo buffer via devm_iio_kfifo_allocate() and
+ * attaches it to the IIO device via iio_device_attach_buffer().
+ * This is meant to be a bit of a short-hand/helper function as there are a few
+ * drivers that seem to do this.
+ */
+int devm_iio_kfifo_buffer_setup_ext(struct device *dev,
+				    struct iio_dev *indio_dev,
+				    const struct iio_buffer_setup_ops *setup_ops,
+				    const struct attribute **buffer_attrs)
+{
+	struct iio_buffer *buffer;
+
+	buffer = devm_iio_kfifo_allocate(dev);
+	if (!buffer)
+		return -ENOMEM;
+
+	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
+	indio_dev->setup_ops = setup_ops;
+
+	buffer->attrs = buffer_attrs;
+
+	return iio_device_attach_buffer(indio_dev, buffer);
+}
+EXPORT_SYMBOL_GPL(devm_iio_kfifo_buffer_setup_ext);
+
+MODULE_LICENSE("GPL");