On 11/27/2011 02:10 PM, Jonathan Cameron wrote:
> From: Jonathan Cameron <jic23@xxxxxxxxx>
>
> This gives you only what you ask for which is handy
> for some devices with weird scan combinations.
>
> Routes all data flow through a core utility function.
> That and this demuxing support will be needed to do
> demuxing to multiple destinations in kernel.
>
> Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxx>
> ---
> drivers/staging/iio/buffer.h | 15 +++
> drivers/staging/iio/industrialio-buffer.c | 148 ++++++++++++++++++++++++++++-
> 2 files changed, 159 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/iio/buffer.h b/drivers/staging/iio/buffer.h
> index 4b8f619..5282441 100644
> --- a/drivers/staging/iio/buffer.h
> +++ b/drivers/staging/iio/buffer.h
> @@ -95,6 +95,8 @@ struct iio_buffer_setup_ops {
> * @access: [DRIVER] buffer access functions associated with the
> * implementation.
> * @flags: [INTERN] file ops related flags including busy flag.
> + * @demux_list: [INTERN] list of operations required to demux the scan.
> + * @demux_bounce: [INTERN] buffer for doing gather from incoming scan.
> **/
> struct iio_buffer {
> struct iio_dev *indio_dev;
> @@ -115,6 +117,8 @@ struct iio_buffer {
> bool stufftoread;
> unsigned long flags;
> const struct attribute_group *attrs;
> + struct list_head demux_list;
> + unsigned char *demux_bounce;
> };
>
> /**
> @@ -153,6 +157,17 @@ int iio_scan_mask_set(struct iio_buffer *buffer, int bit);
> container_of(d, struct iio_buffer, dev)
>
> /**
> + * iio_push_to_buffer() - push to a registered buffer.
> + * @buffer: IIO buffer structure for device
> + * @scan: Full scan.
> + * @timestamp:
> + */
> +int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
> + s64 timestamp);
> +
> +int iio_update_demux(struct iio_dev *indio_dev);
> +
> +/**
> * iio_buffer_register() - register the buffer with IIO core
> * @indio_dev: device with the buffer to be registered
> **/
> diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
> index fb14e37..352f9f1 100644
> --- a/drivers/staging/iio/industrialio-buffer.c
> +++ b/drivers/staging/iio/industrialio-buffer.c
> @@ -87,6 +87,7 @@ void iio_chrdev_buffer_release(struct iio_dev *indio_dev)
>
> void iio_buffer_init(struct iio_buffer *buffer, struct iio_dev *indio_dev)
> {
> + INIT_LIST_HEAD(&buffer->demux_list);
> buffer->indio_dev = indio_dev;
> init_waitqueue_head(&buffer->pollq);
> }
> @@ -128,10 +129,9 @@ static ssize_t iio_scan_el_show(struct device *dev,
> int ret;
> struct iio_dev *indio_dev = dev_get_drvdata(dev);
>
> - ret = iio_scan_mask_query(indio_dev->buffer,
> - to_iio_dev_attr(attr)->address);
> - if (ret < 0)
> - return ret;
> + ret = test_bit(to_iio_dev_attr(attr)->address,
> + indio_dev->buffer->scan_mask);
> +
> return sprintf(buf, "%d\n", ret);
> }
>
> @@ -583,6 +583,12 @@ int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
> buffer->scan_mask);
> else
> indio_dev->active_scan_mask = buffer->scan_mask;
> + iio_update_demux(indio_dev);
> +
> + if (indio_dev->info->update_scan_mode)
> + return indio_dev->info
> + ->update_scan_mode(indio_dev,
> + indio_dev->active_scan_mask);
> return 0;
> }
> EXPORT_SYMBOL(iio_sw_buffer_preenable);
> @@ -652,3 +658,137 @@ int iio_scan_mask_query(struct iio_buffer *buffer, int bit)
> return test_bit(bit, mask);
> };
> EXPORT_SYMBOL_GPL(iio_scan_mask_query);
> +
> +/**
> + * struct iio_demux_table() - table describing demux memcpy ops
> + * @from: index to copy from
> + * @to: index to copy to
> + * @length: how many bytes to copy
> + * @l: list head used for management
> + */
> +struct iio_demux_table {
> + unsigned from;
> + unsigned to;
> + unsigned length;
> + struct list_head l;
> +};
> +
> +static unsigned char *iio_demux(struct iio_buffer *buffer,
> + unsigned char *datain)
> +{
> + struct iio_demux_table *t;
> +
> + if (list_empty(&buffer->demux_list))
> + return datain;
> + list_for_each_entry(t, &buffer->demux_list, l)
> + memcpy(buffer->demux_bounce + t->to,
> + datain + t->from, t->length);
> +
> + return buffer->demux_bounce;
> +}
> +
> +int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
> + s64 timestamp)
> +{
> + unsigned char *dataout = iio_demux(buffer, data);
> +
> + return buffer->access->store_to(buffer, dataout, timestamp);
> +}
> +EXPORT_SYMBOL_GPL(iio_push_to_buffer);
I wonder if we want to integrate the demuxing into the store_to callbacks of
the buffer, this would avoid the need for the bounce buffer and reduce the
number of memcpys. But maybe we can just add it later.
> +
> +int iio_update_demux(struct iio_dev *indio_dev)
> +{
> + const struct iio_chan_spec *ch;
> + struct iio_buffer *buffer = indio_dev->buffer;
> + int ret, in_ind = -1, out_ind, length;
> + unsigned in_loc = 0, out_loc = 0;
> + struct iio_demux_table *p, *q;
> +
> + /* Clear out any old demux */
> + list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
> + list_del(&p->l);
> + kfree(p);
> + }
> + kfree(buffer->demux_bounce);
> + buffer->demux_bounce = NULL;
> +
> + /* First work out which scan mode we will actually have */
> + if (bitmap_equal(indio_dev->active_scan_mask,
> + buffer->scan_mask,
> + indio_dev->masklength))
> + return 0;
> +
> + out_ind = find_first_bit(buffer->scan_mask, indio_dev->masklength);
> + /* Now we have the two masks, work from least sig and build up sizes */
> + while (out_ind != indio_dev->masklength) {
This looks a bit like an open-coded for_each_set_bit
> + in_ind = find_next_bit(indio_dev->active_scan_mask,
> + indio_dev->masklength,
> + in_ind + 1);
> + while (in_ind != out_ind) {
> + in_ind = find_next_bit(indio_dev->active_scan_mask,
> + indio_dev->masklength,
> + in_ind + 1);
same here for_each_set_bit(in_ind, indio->active_scan_mask, out_ind)
> + ch = iio_find_channel_from_si(indio_dev, in_ind);
> + length = ch->scan_type.storagebits/8;
> + /* Make sure we are aligned */
> + in_loc += length;
> + if (in_loc % length)
> + in_loc += length - in_loc % length;
> + }
> + p = kmalloc(sizeof(*p), GFP_KERNEL);
> + if (p == NULL) {
> + ret = -ENOMEM;
> + goto error_clear_mux_table;
> + }
> + ch = iio_find_channel_from_si(indio_dev, in_ind);
> + length = ch->scan_type.storagebits/8;
> + if (out_loc % length)
> + out_loc += length - out_loc % length;
> + if (in_loc % length)
> + in_loc += length - in_loc % length;
> + p->from = in_loc;
> + p->to = out_loc;
> + p->length = length;
> + list_add_tail(&p->l, &buffer->demux_list);
> + out_loc += length;
> + in_loc += length;
> + out_ind = find_next_bit(buffer->scan_mask,
> + indio_dev->masklength,
> + out_ind + 1);
> + }
> + /* Relies on scan_timestamp being last */
> + if (buffer->scan_timestamp) {
> + p = kmalloc(sizeof(*p), GFP_KERNEL);
> + if (p == NULL) {
> + ret = -ENOMEM;
> + goto error_clear_mux_table;
> + }
> + ch = iio_find_channel_from_si(indio_dev,
> + buffer->scan_index_timestamp);
> + length = ch->scan_type.storagebits/8;
> + if (out_loc % length)
> + out_loc += length - out_loc % length;
> + if (in_loc % length)
> + in_loc += length - in_loc % length;
> + p->from = in_loc;
> + p->to = out_loc;
> + p->length = length;
> + list_add_tail(&p->l, &buffer->demux_list);
> + out_loc += length;
> + in_loc += length;
> + }
> + buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
> + if (buffer->demux_bounce == NULL) {
> + ret = -ENOMEM;
> + goto error_clear_mux_table;
> + }
> + return 0;
> +
> +error_clear_mux_table:
> + list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
> + list_del(&p->l);
> + kfree(p);
> + }
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(iio_update_demux);
--
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