Re: [PATCH v4 01/12] iio: Add hardware consumer buffer support

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On Thu, 9 Nov 2017 11:12:23 +0100
Arnaud Pouliquen <arnaud.pouliquen-qxv4g6HH51o@public.gmane.org> wrote:

> From: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
> 
> Hardware consumer interface can be used when one IIO device has
> a direct connection to another device in hardware.
> 
> Signed-off-by: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen-qxv4g6HH51o@public.gmane.org>

I think this is fine though it is something we will have to
keep an eye on to make sure it is appropriately used...

Jonathan

> ---
>  drivers/iio/buffer/Kconfig                    |  10 ++
>  drivers/iio/buffer/Makefile                   |   1 +
>  drivers/iio/buffer/industrialio-hw-consumer.c | 182 ++++++++++++++++++++++++++
>  include/linux/iio/hw-consumer.h               |  20 +++
>  4 files changed, 213 insertions(+)
>  create mode 100644 drivers/iio/buffer/industrialio-hw-consumer.c
>  create mode 100644 include/linux/iio/hw-consumer.h
> 
> diff --git a/drivers/iio/buffer/Kconfig b/drivers/iio/buffer/Kconfig
> index 4ffd3db..338774c 100644
> --- a/drivers/iio/buffer/Kconfig
> +++ b/drivers/iio/buffer/Kconfig
> @@ -29,6 +29,16 @@ config IIO_BUFFER_DMAENGINE
>  
>  	  Should be selected by drivers that want to use this functionality.
>  
> +config IIO_BUFFER_HW_CONSUMER
> +	tristate "Industrial I/O HW buffering"
> +	help
> +	  Provides a way to bonding when an IIO device has a direct connection
> +	  to another device in hardware. In this case buffers for data transfers
> +	  are handled by hardware.
> +
> +	  Should be selected by drivers that want to use the generic Hw consumer
> +	  interface.
> +
>  config IIO_KFIFO_BUF
>  	tristate "Industrial I/O buffering based on kfifo"
>  	help
> diff --git a/drivers/iio/buffer/Makefile b/drivers/iio/buffer/Makefile
> index 85beaae..324a36b 100644
> --- a/drivers/iio/buffer/Makefile
> +++ b/drivers/iio/buffer/Makefile
> @@ -6,5 +6,6 @@
>  obj-$(CONFIG_IIO_BUFFER_CB) += industrialio-buffer-cb.o
>  obj-$(CONFIG_IIO_BUFFER_DMA) += industrialio-buffer-dma.o
>  obj-$(CONFIG_IIO_BUFFER_DMAENGINE) += industrialio-buffer-dmaengine.o
> +obj-$(CONFIG_IIO_BUFFER_HW_CONSUMER) += industrialio-hw-consumer.o
>  obj-$(CONFIG_IIO_TRIGGERED_BUFFER) += industrialio-triggered-buffer.o
>  obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
> diff --git a/drivers/iio/buffer/industrialio-hw-consumer.c b/drivers/iio/buffer/industrialio-hw-consumer.c
> new file mode 100644
> index 0000000..7d4d800
> --- /dev/null
> +++ b/drivers/iio/buffer/industrialio-hw-consumer.c
> @@ -0,0 +1,182 @@
> +/*
> + * Copyright 2017 Analog Devices Inc.
> + *  Author: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/export.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/iio/hw-consumer.h>
> +#include <linux/iio/buffer_impl.h>
> +
> +/**
> + * struct iio_hw_consumer - IIO hw consumer block
> + * @buffers: hardware buffers list head.
> + * @channels: IIO provider channels.
> + */
> +struct iio_hw_consumer {
> +	struct list_head buffers;
> +	struct iio_channel *channels;
> +};
> +
> +struct hw_consumer_buffer {
> +	struct list_head head;
> +	struct iio_dev *indio_dev;
> +	struct iio_buffer buffer;
> +	long scan_mask[];
> +};
> +
> +static struct hw_consumer_buffer *iio_buffer_to_hw_consumer_buffer(
> +	struct iio_buffer *buffer)
> +{
> +	return container_of(buffer, struct hw_consumer_buffer, buffer);
> +}
> +
> +static void iio_hw_buf_release(struct iio_buffer *buffer)
> +{
> +	struct hw_consumer_buffer *hw_buf =
> +		iio_buffer_to_hw_consumer_buffer(buffer);
> +	kfree(hw_buf);
> +}
> +
> +static const struct iio_buffer_access_funcs iio_hw_buf_access = {
> +	.release = &iio_hw_buf_release,
> +	.modes = INDIO_BUFFER_HARDWARE,
> +};
> +
> +static struct hw_consumer_buffer *iio_hw_consumer_get_buffer(
> +	struct iio_hw_consumer *hwc, struct iio_dev *indio_dev)
> +{
> +	size_t mask_size = BITS_TO_LONGS(indio_dev->masklength) * sizeof(long);
> +	struct hw_consumer_buffer *buf;
> +
> +	list_for_each_entry(buf, &hwc->buffers, head) {
> +		if (buf->indio_dev == indio_dev)
> +			return buf;
> +	}
> +
> +	buf = kzalloc(sizeof(*buf) + mask_size, GFP_KERNEL);
> +	if (!buf)
> +		return NULL;
> +
> +	buf->buffer.access = &iio_hw_buf_access;
> +	buf->indio_dev = indio_dev;
> +	buf->buffer.scan_mask = buf->scan_mask;
> +
> +	iio_buffer_init(&buf->buffer);
> +	list_add_tail(&buf->head, &hwc->buffers);
> +
> +	return buf;
> +}
> +
> +/**
> + * iio_hw_consumer_alloc() - Allocate IIO hardware consumer
> + * @dev: Pointer to consumer device.
> + *
> + * Returns a valid iio_hw_consumer on success or a ERR_PTR() on failure.
> + */
> +struct iio_hw_consumer *iio_hw_consumer_alloc(struct device *dev)
> +{
> +	struct hw_consumer_buffer *buf;
> +	struct iio_hw_consumer *hwc;
> +	struct iio_channel *chan;
> +	int ret;
> +
> +	hwc = kzalloc(sizeof(*hwc), GFP_KERNEL);
> +	if (!hwc)
> +		return ERR_PTR(-ENOMEM);
> +
> +	INIT_LIST_HEAD(&hwc->buffers);
> +
> +	hwc->channels = iio_channel_get_all(dev);
> +	if (IS_ERR(hwc->channels)) {
> +		ret = PTR_ERR(hwc->channels);
> +		goto err_free_hwc;
> +	}
> +
> +	chan = &hwc->channels[0];
> +	while (chan->indio_dev) {
> +		buf = iio_hw_consumer_get_buffer(hwc, chan->indio_dev);
> +		if (!buf) {
> +			ret = -ENOMEM;
> +			goto err_put_buffers;
> +		}
> +		set_bit(chan->channel->scan_index, buf->buffer.scan_mask);
> +		chan++;
> +	}
> +
> +	return hwc;
> +
> +err_put_buffers:
> +	list_for_each_entry(buf, &hwc->buffers, head)
> +		iio_buffer_put(&buf->buffer);
> +	iio_channel_release_all(hwc->channels);
> +err_free_hwc:
> +	kfree(hwc);
> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(iio_hw_consumer_alloc);
> +
> +/**
> + * iio_hw_consumer_free() - Free IIO hardware consumer
> + * @hwc: hw consumer to free.
> + */
> +void iio_hw_consumer_free(struct iio_hw_consumer *hwc)
> +{
> +	struct hw_consumer_buffer *buf;
> +
> +	iio_channel_release_all(hwc->channels);
> +	list_for_each_entry(buf, &hwc->buffers, head)
> +		iio_buffer_put(&buf->buffer);
> +	kfree(hwc);
> +}
> +EXPORT_SYMBOL_GPL(iio_hw_consumer_free);
> +
> +/**
> + * iio_hw_consumer_enable() - Enable IIO hardware consumer
> + * @hwc: iio_hw_consumer to enable.
> + *
> + * Returns 0 on success.
> + */
> +int iio_hw_consumer_enable(struct iio_hw_consumer *hwc)
> +{
> +	struct hw_consumer_buffer *buf;
> +	int ret;
> +
> +	list_for_each_entry(buf, &hwc->buffers, head) {
> +		ret = iio_update_buffers(buf->indio_dev, &buf->buffer, NULL);
> +		if (ret)
> +			goto err_disable_buffers;
> +	}
> +
> +	return 0;
> +
> +err_disable_buffers:
> +	list_for_each_entry_continue_reverse(buf, &hwc->buffers, head)
> +		iio_update_buffers(buf->indio_dev, NULL, &buf->buffer);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iio_hw_consumer_enable);
> +
> +/**
> + * iio_hw_consumer_disable() - Disable IIO hardware consumer
> + * @hwc: iio_hw_consumer to disable.
> + */
> +void iio_hw_consumer_disable(struct iio_hw_consumer *hwc)
> +{
> +	struct hw_consumer_buffer *buf;
> +
> +	list_for_each_entry(buf, &hwc->buffers, head)
> +		iio_update_buffers(buf->indio_dev, NULL, &buf->buffer);
> +}
> +EXPORT_SYMBOL_GPL(iio_hw_consumer_disable);
> +
> +MODULE_AUTHOR("Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>");
> +MODULE_DESCRIPTION("Hardware consumer buffer the IIO framework");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/iio/hw-consumer.h b/include/linux/iio/hw-consumer.h
> new file mode 100644
> index 0000000..f16791b
> --- /dev/null
> +++ b/include/linux/iio/hw-consumer.h
> @@ -0,0 +1,20 @@
> +/*
> + * Industrial I/O in kernel hardware consumer interface
> + *
> + * Copyright 2017 Analog Devices Inc.
> + *  Author: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#ifndef LINUX_IIO_HW_CONSUMER_H
> +#define LINUX_IIO_HW_CONSUMER_H
> +
> +struct iio_hw_consumer;
> +
> +struct iio_hw_consumer *iio_hw_consumer_alloc(struct device *dev);
> +void iio_hw_consumer_free(struct iio_hw_consumer *hwc);
> +int iio_hw_consumer_enable(struct iio_hw_consumer *hwc);
> +void iio_hw_consumer_disable(struct iio_hw_consumer *hwc);
> +
> +#endif