On 11/28/2011 09:39 AM, Lars-Peter Clausen wrote:
> 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.
I'd rather do this later than mess too much with the buffers in this
patch. I think we may want to do it the other way around and have
buffers offer a reserve_space and done_with_space pair of callbacks
where the first saves the room and passes back a pointer. Then demux
can occur directly into there rather than the bounce buffer.
Still, same effective result! So not now in my view.
>
> This looks a bit like an open-coded for_each_set_bit
Indeed. Will clean that up.
>
>> + 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)
close but not quite. It only counts bits above the previous in_ind
(which is also the previous out_ind). Need a for_each_set_bit_after
function for this.
>
>> + 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);
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
