iio: proximity: vl53l0x-i2c: claim direct mode for raw readsgrafted

vl53l0x_read_raw() starts a single-shot ranging measurement and reads
back the result. Once the triggered buffer is enabled the sensor runs in
continuous mode and its data-ready interrupt is routed to the trigger,
so a concurrent in_distance_raw read disturbs the streaming setup and
never gets its completion, returning -ETIMEDOUT.

The original submission claimed direct mode here, but it was dropped
during review because the driver had no buffer support at the time [1].
Continuous (buffered) mode was later added without restoring the
claim [2], reintroducing the conflict.

Reject direct reads while buffered capture is active by claiming direct
mode around the measurement, as the vl53l1x sibling already does.

Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support")
Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1]
Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2]
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>

1 files changed, 465 insertions, 0 deletions

diff --git a/drivers/iio/buffer/industrialio-buffer-dmaengine.c b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
new file mode 100644
index 000000000..376486be3
--- /dev/null
+++ b/drivers/iio/buffer/industrialio-buffer-dmaengine.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2014-2015 Analog Devices Inc.
+ *  Author: Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/cleanup.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/spinlock.h>
+#include <linux/err.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/buffer_impl.h>
+#include <linux/iio/buffer-dma.h>
+#include <linux/iio/buffer-dmaengine.h>
+
+/*
+ * The IIO DMAengine buffer combines the generic IIO DMA buffer infrastructure
+ * with the DMAengine framework. The generic IIO DMA buffer infrastructure is
+ * used to manage the buffer memory and implement the IIO buffer operations
+ * while the DMAengine framework is used to perform the DMA transfers. Combined
+ * this results in a device independent fully functional DMA buffer
+ * implementation that can be used by device drivers for peripherals which are
+ * connected to a DMA controller which has a DMAengine driver implementation.
+ */
+
+struct dmaengine_buffer {
+	struct iio_dma_buffer_queue queue;
+
+	struct dma_chan *chan;
+	struct list_head active;
+
+	size_t align;
+	size_t max_size;
+};
+
+static struct dmaengine_buffer *iio_buffer_to_dmaengine_buffer(struct iio_buffer *buffer)
+{
+	return container_of(buffer, struct dmaengine_buffer, queue.buffer);
+}
+
+static void iio_dmaengine_buffer_block_done(void *data,
+					    const struct dmaengine_result *result)
+{
+	struct iio_dma_buffer_block *block = data;
+
+	scoped_guard(spinlock_irqsave, &block->queue->list_lock)
+		list_del(&block->head);
+	block->bytes_used -= result->residue;
+	iio_dma_buffer_block_done(block);
+}
+
+/*
+ * Cyclic transfers run until abort. Cap active cyclic blocks to one until there
+ * is a use case for more.
+ */
+static bool iio_dmaengine_buffer_has_active_cyclic(struct dmaengine_buffer *dmaengine_buffer)
+{
+	struct iio_dma_buffer_block *block;
+
+	guard(spinlock_irqsave)(&dmaengine_buffer->queue.list_lock);
+	list_for_each_entry(block, &dmaengine_buffer->active, head) {
+		if (block->cyclic)
+			return true;
+	}
+
+	return false;
+}
+
+static int iio_dmaengine_buffer_submit_block(struct iio_dma_buffer_queue *queue,
+					     struct iio_dma_buffer_block *block)
+{
+	struct dmaengine_buffer *dmaengine_buffer =
+		iio_buffer_to_dmaengine_buffer(&queue->buffer);
+	struct dma_async_tx_descriptor *desc;
+	enum dma_transfer_direction dma_dir;
+	struct scatterlist *sgl;
+	struct dma_vec *vecs;
+	size_t max_size;
+	dma_cookie_t cookie;
+	size_t len_total;
+	unsigned int i;
+	int nents;
+
+	max_size = min(block->size, dmaengine_buffer->max_size);
+	max_size = round_down(max_size, dmaengine_buffer->align);
+
+	if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN)
+		dma_dir = DMA_DEV_TO_MEM;
+	else
+		dma_dir = DMA_MEM_TO_DEV;
+
+	if (block->cyclic && iio_dmaengine_buffer_has_active_cyclic(dmaengine_buffer)) {
+		dev_err(queue->dev, "cyclic DMA transfer already active\n");
+		return -EBUSY;
+	}
+
+	if (block->sg_table) {
+		unsigned long flags;
+
+		/*
+		 * Only the first sgt->nents entries carry a valid
+		 * sg_dma_address()/sg_dma_len() pair as mapping the table may
+		 * have coalesced entries, in which case nents is smaller than
+		 * orig_nents.
+		 */
+		nents = block->sg_table->nents;
+
+		vecs = kmalloc_array(nents, sizeof(*vecs), GFP_ATOMIC);
+		if (!vecs)
+			return -ENOMEM;
+
+		len_total = block->bytes_used;
+
+		sgl = block->sg_table->sgl;
+		for (i = 0; i < nents && len_total; i++) {
+			vecs[i].addr = sg_dma_address(sgl);
+			vecs[i].len = min(sg_dma_len(sgl), len_total);
+			len_total -= vecs[i].len;
+
+			sgl = sg_next(sgl);
+		}
+
+		nents = i;
+
+		if (block->cyclic)
+			flags = DMA_PREP_REPEAT;
+		else
+			flags = DMA_PREP_INTERRUPT;
+
+		/*
+		 * A new transfer may need to end an already active cyclic transfer
+		 * before it can run, so always set the EOT flag.
+		 */
+		flags |= DMA_PREP_LOAD_EOT;
+		desc = dmaengine_prep_peripheral_dma_vec(dmaengine_buffer->chan,
+							 vecs, nents, dma_dir,
+							 flags);
+		kfree(vecs);
+	} else {
+		max_size = min(block->size, dmaengine_buffer->max_size);
+		max_size = round_down(max_size, dmaengine_buffer->align);
+
+		if (queue->buffer.direction == IIO_BUFFER_DIRECTION_IN)
+			block->bytes_used = max_size;
+
+		if (!block->bytes_used || block->bytes_used > max_size)
+			return -EINVAL;
+
+		desc = dmaengine_prep_slave_single(dmaengine_buffer->chan,
+						   block->phys_addr,
+						   block->bytes_used,
+						   dma_dir,
+						   DMA_PREP_INTERRUPT);
+	}
+	if (!desc)
+		return -ENOMEM;
+
+	if (!block->cyclic) {
+		desc->callback_result = iio_dmaengine_buffer_block_done;
+		desc->callback_param = block;
+	}
+
+	cookie = dmaengine_submit(desc);
+	if (dma_submit_error(cookie))
+		return dma_submit_error(cookie);
+
+	scoped_guard(spinlock_irq, &dmaengine_buffer->queue.list_lock)
+		list_add_tail(&block->head, &dmaengine_buffer->active);
+
+	dma_async_issue_pending(dmaengine_buffer->chan);
+
+	return 0;
+}
+
+static void iio_dmaengine_buffer_abort(struct iio_dma_buffer_queue *queue)
+{
+	struct dmaengine_buffer *dmaengine_buffer =
+		iio_buffer_to_dmaengine_buffer(&queue->buffer);
+
+	dmaengine_terminate_sync(dmaengine_buffer->chan);
+	iio_dma_buffer_block_list_abort(queue, &dmaengine_buffer->active);
+}
+
+static void iio_dmaengine_buffer_release(struct iio_buffer *buf)
+{
+	struct dmaengine_buffer *dmaengine_buffer =
+		iio_buffer_to_dmaengine_buffer(buf);
+
+	iio_dma_buffer_release(&dmaengine_buffer->queue);
+	kfree(dmaengine_buffer);
+}
+
+static const struct iio_buffer_access_funcs iio_dmaengine_buffer_ops = {
+	.read = iio_dma_buffer_read,
+	.write = iio_dma_buffer_write,
+	.set_bytes_per_datum = iio_dma_buffer_set_bytes_per_datum,
+	.set_length = iio_dma_buffer_set_length,
+	.request_update = iio_dma_buffer_request_update,
+	.enable = iio_dma_buffer_enable,
+	.disable = iio_dma_buffer_disable,
+	.data_available = iio_dma_buffer_usage,
+	.space_available = iio_dma_buffer_usage,
+	.release = iio_dmaengine_buffer_release,
+
+	.enqueue_dmabuf = iio_dma_buffer_enqueue_dmabuf,
+	.attach_dmabuf = iio_dma_buffer_attach_dmabuf,
+	.detach_dmabuf = iio_dma_buffer_detach_dmabuf,
+
+	.lock_queue = iio_dma_buffer_lock_queue,
+	.unlock_queue = iio_dma_buffer_unlock_queue,
+
+	.get_dma_dev = iio_dma_buffer_get_dma_dev,
+
+	.modes = INDIO_BUFFER_HARDWARE,
+	.flags = INDIO_BUFFER_FLAG_FIXED_WATERMARK,
+};
+
+static const struct iio_dma_buffer_ops iio_dmaengine_default_ops = {
+	.submit = iio_dmaengine_buffer_submit_block,
+	.abort = iio_dmaengine_buffer_abort,
+};
+
+static ssize_t iio_dmaengine_buffer_get_length_align(struct device *dev,
+						     struct device_attribute *attr, char *buf)
+{
+	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
+	struct dmaengine_buffer *dmaengine_buffer =
+		iio_buffer_to_dmaengine_buffer(buffer);
+
+	return sysfs_emit(buf, "%zu\n", dmaengine_buffer->align);
+}
+
+static IIO_DEVICE_ATTR(length_align_bytes, 0444,
+		       iio_dmaengine_buffer_get_length_align, NULL, 0);
+
+static const struct iio_dev_attr *iio_dmaengine_buffer_attrs[] = {
+	&iio_dev_attr_length_align_bytes,
+	NULL,
+};
+
+/**
+ * iio_dmaengine_buffer_alloc() - Allocate new buffer which uses DMAengine
+ * @chan: DMA channel.
+ *
+ * This allocates a new IIO buffer which internally uses the DMAengine framework
+ * to perform its transfers.
+ *
+ * Once done using the buffer iio_dmaengine_buffer_free() should be used to
+ * release it.
+ */
+static struct iio_buffer *iio_dmaengine_buffer_alloc(struct dma_chan *chan)
+{
+	struct dmaengine_buffer *dmaengine_buffer;
+	unsigned int width, src_width, dest_width;
+	struct dma_slave_caps caps;
+	int ret;
+
+	ret = dma_get_slave_caps(chan, &caps);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	dmaengine_buffer = kzalloc_obj(*dmaengine_buffer);
+	if (!dmaengine_buffer)
+		return ERR_PTR(-ENOMEM);
+
+	/* Needs to be aligned to the maximum of the minimums */
+	if (caps.src_addr_widths)
+		src_width = __ffs(caps.src_addr_widths);
+	else
+		src_width = 1;
+	if (caps.dst_addr_widths)
+		dest_width = __ffs(caps.dst_addr_widths);
+	else
+		dest_width = 1;
+	width = max(src_width, dest_width);
+
+	INIT_LIST_HEAD(&dmaengine_buffer->active);
+	dmaengine_buffer->chan = chan;
+	dmaengine_buffer->align = width;
+	dmaengine_buffer->max_size = dma_get_max_seg_size(chan->device->dev);
+
+	iio_dma_buffer_init(&dmaengine_buffer->queue, chan->device->dev,
+			    &iio_dmaengine_default_ops);
+
+	dmaengine_buffer->queue.buffer.attrs = iio_dmaengine_buffer_attrs;
+	dmaengine_buffer->queue.buffer.access = &iio_dmaengine_buffer_ops;
+
+	return &dmaengine_buffer->queue.buffer;
+}
+
+/**
+ * iio_dmaengine_buffer_free() - Free dmaengine buffer
+ * @buffer: Buffer to free
+ *
+ * Frees a buffer previously allocated with iio_dmaengine_buffer_alloc().
+ */
+static void iio_dmaengine_buffer_free(struct iio_buffer *buffer)
+{
+	struct dmaengine_buffer *dmaengine_buffer =
+		iio_buffer_to_dmaengine_buffer(buffer);
+
+	iio_dma_buffer_exit(&dmaengine_buffer->queue);
+	iio_buffer_put(buffer);
+}
+
+/**
+ * iio_dmaengine_buffer_teardown() - Releases DMA channel and frees buffer
+ * @buffer: Buffer to free
+ *
+ * Releases the DMA channel and frees the buffer previously setup with
+ * iio_dmaengine_buffer_setup_ext().
+ */
+void iio_dmaengine_buffer_teardown(struct iio_buffer *buffer)
+{
+	struct dmaengine_buffer *dmaengine_buffer =
+		iio_buffer_to_dmaengine_buffer(buffer);
+	struct dma_chan *chan = dmaengine_buffer->chan;
+
+	iio_dmaengine_buffer_free(buffer);
+	dma_release_channel(chan);
+}
+EXPORT_SYMBOL_NS_GPL(iio_dmaengine_buffer_teardown, "IIO_DMAENGINE_BUFFER");
+
+static struct iio_buffer
+*__iio_dmaengine_buffer_setup_ext(struct iio_dev *indio_dev,
+				  struct dma_chan *chan,
+				  enum iio_buffer_direction dir)
+{
+	struct iio_buffer *buffer;
+	int ret;
+
+	buffer = iio_dmaengine_buffer_alloc(chan);
+	if (IS_ERR(buffer))
+		return ERR_CAST(buffer);
+
+	indio_dev->modes |= INDIO_BUFFER_HARDWARE;
+
+	buffer->direction = dir;
+
+	ret = iio_device_attach_buffer(indio_dev, buffer);
+	if (ret) {
+		iio_dmaengine_buffer_free(buffer);
+		return ERR_PTR(ret);
+	}
+
+	return buffer;
+}
+
+/**
+ * iio_dmaengine_buffer_setup_ext() - Setup a DMA buffer for an IIO device
+ * @dev: DMA channel consumer device
+ * @indio_dev: IIO device to which to attach this buffer.
+ * @channel: DMA channel name, typically "rx".
+ * @dir: Direction of buffer (in or out)
+ *
+ * This allocates a new IIO buffer with devm_iio_dmaengine_buffer_alloc()
+ * and attaches it to an IIO device with iio_device_attach_buffer().
+ * It also appends the INDIO_BUFFER_HARDWARE mode to the supported modes of the
+ * IIO device.
+ *
+ * Once done using the buffer iio_dmaengine_buffer_teardown() should be used to
+ * release it.
+ */
+struct iio_buffer *iio_dmaengine_buffer_setup_ext(struct device *dev,
+						  struct iio_dev *indio_dev,
+						  const char *channel,
+						  enum iio_buffer_direction dir)
+{
+	struct dma_chan *chan;
+	struct iio_buffer *buffer;
+
+	chan = dma_request_chan(dev, channel);
+	if (IS_ERR(chan))
+		return ERR_CAST(chan);
+
+	buffer = __iio_dmaengine_buffer_setup_ext(indio_dev, chan, dir);
+	if (IS_ERR(buffer))
+		dma_release_channel(chan);
+
+	return buffer;
+}
+EXPORT_SYMBOL_NS_GPL(iio_dmaengine_buffer_setup_ext, "IIO_DMAENGINE_BUFFER");
+
+static void devm_iio_dmaengine_buffer_teardown(void *buffer)
+{
+	iio_dmaengine_buffer_teardown(buffer);
+}
+
+/**
+ * devm_iio_dmaengine_buffer_setup_ext() - Setup a DMA buffer for an IIO device
+ * @dev: Device for devm ownership and DMA channel consumer device
+ * @indio_dev: IIO device to which to attach this buffer.
+ * @channel: DMA channel name, typically "rx".
+ * @dir: Direction of buffer (in or out)
+ *
+ * This allocates a new IIO buffer with devm_iio_dmaengine_buffer_alloc()
+ * and attaches it to an IIO device with iio_device_attach_buffer().
+ * It also appends the INDIO_BUFFER_HARDWARE mode to the supported modes of the
+ * IIO device.
+ */
+int devm_iio_dmaengine_buffer_setup_ext(struct device *dev,
+					struct iio_dev *indio_dev,
+					const char *channel,
+					enum iio_buffer_direction dir)
+{
+	struct iio_buffer *buffer;
+
+	buffer = iio_dmaengine_buffer_setup_ext(dev, indio_dev, channel, dir);
+	if (IS_ERR(buffer))
+		return PTR_ERR(buffer);
+
+	return devm_add_action_or_reset(dev, devm_iio_dmaengine_buffer_teardown,
+					buffer);
+}
+EXPORT_SYMBOL_NS_GPL(devm_iio_dmaengine_buffer_setup_ext, "IIO_DMAENGINE_BUFFER");
+
+static void devm_iio_dmaengine_buffer_free(void *buffer)
+{
+	iio_dmaengine_buffer_free(buffer);
+}
+
+/**
+ * devm_iio_dmaengine_buffer_setup_with_handle() - Setup a DMA buffer for an
+ *						   IIO device
+ * @dev: Device for devm ownership
+ * @indio_dev: IIO device to which to attach this buffer.
+ * @chan: DMA channel
+ * @dir: Direction of buffer (in or out)
+ *
+ * This allocates a new IIO buffer with devm_iio_dmaengine_buffer_alloc()
+ * and attaches it to an IIO device with iio_device_attach_buffer().
+ * It also appends the INDIO_BUFFER_HARDWARE mode to the supported modes of the
+ * IIO device.
+ *
+ * This is the same as devm_iio_dmaengine_buffer_setup_ext() except that the
+ * caller manages requesting and releasing the DMA channel handle.
+ */
+int devm_iio_dmaengine_buffer_setup_with_handle(struct device *dev,
+						struct iio_dev *indio_dev,
+						struct dma_chan *chan,
+						enum iio_buffer_direction dir)
+{
+	struct iio_buffer *buffer;
+
+	buffer = __iio_dmaengine_buffer_setup_ext(indio_dev, chan, dir);
+	if (IS_ERR(buffer))
+		return PTR_ERR(buffer);
+
+	return devm_add_action_or_reset(dev, devm_iio_dmaengine_buffer_free,
+					buffer);
+}
+EXPORT_SYMBOL_NS_GPL(devm_iio_dmaengine_buffer_setup_with_handle,
+		     "IIO_DMAENGINE_BUFFER");
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("DMA buffer for the IIO framework");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_DMA_BUFFER");