> -----Original Message----- > From: Jonathan Cameron <jic23@xxxxxxxxxx> > Sent: Thursday, 7 October 2021 19:06 > To: Chindris, Mihail <Mihail.Chindris@xxxxxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-iio@xxxxxxxxxxxxxxx; > lars@xxxxxxxxxx; Hennerich, Michael <Michael.Hennerich@xxxxxxxxxx>; > Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; Bogdan, Dragos > <Dragos.Bogdan@xxxxxxxxxx>; alexandru.ardelean@xxxxxxxxxx > Subject: Re: [PATCH v6 1/6] iio: Add output buffer support > > On Thu, 7 Oct 2021 08:00:30 +0000 > Mihail Chindris <mihail.chindris@xxxxxxxxxx> wrote: > > > Currently IIO only supports buffer mode for capture devices like ADCs. > > Add support for buffered mode for output devices like DACs. > > > > The output buffer implementation is analogous to the input buffer > > implementation. Instead of using read() to get data from the buffer > > write() is used to copy data into the buffer. > > > > poll() with POLLOUT will wakeup if there is space available. > > > > Drivers can remove data from a buffer using iio_pop_from_buffer(), the > > function can e.g. called from a trigger handler to write the data to > > hardware. > > > > A buffer can only be either a output buffer or an input, but not both. > > So, for a device that has an ADC and DAC path, this will mean 2 IIO > > buffers (one for each direction). > > > > The direction of the buffer is decided by the new direction field of > > the iio_buffer struct and should be set after allocating and before > > registering it. > > > > Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx> > > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> > > Signed-off-by: Mihail Chindris <mihail.chindris@xxxxxxxxxx> > > Hi Mihail, > > I'm fine with this series now, but one question for this patch on whether we > can clarify the author chain. > > The above might mean one of two things. > 1) Lars wrote the code and Alex and yourself just 'handled' the patch on its > way to posting. If that were the case it should have a From: for Lars > 2) All 3 were involved in changes to this patch. In that case we should have > Co-developed-by: lines for lars and Alex as described: > https://urldefense.com/v3/__https://elixir.bootlin.com/linux/latest/source/ > Documentation/process/submitting- > patches.rst*L475__;Iw!!A3Ni8CS0y2Y!t1IaOEZX3w2pZXl- > RyAlXgPPvxFtCON74ppfGuMgV_pKZcNjsLs-dKSk_mA34IsmlOU$ > > This patch has a history well predating the Co-developed-tag but I'm happy > to add that if you can confirm that matches with the intent. > > Good to leave on the list for a few days anyway in case anyone else wants to > take a quick look. > > I'm looking forwards to merging this and thinking back to when Lars originally > discussed this feature with me rather a lot of years back! > > Jonathan > > Hi Jonathan, What I have done with the patch was to take the V3 that Alex has left and implement the feedback. So I think this is considered as 'handled' from my side. What happened before V3 I think is better if Alex spokes for himself because I don't really know :) Mihail > > > --- > > drivers/iio/iio_core.h | 4 + > > drivers/iio/industrialio-buffer.c | 127 > +++++++++++++++++++++++++++++- > > drivers/iio/industrialio-core.c | 1 + > > include/linux/iio/buffer.h | 7 ++ > > include/linux/iio/buffer_impl.h | 11 +++ > > 5 files changed, 148 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h index > > 8f4a9b264962..61e318431de9 100644 > > --- a/drivers/iio/iio_core.h > > +++ b/drivers/iio/iio_core.h > > @@ -68,12 +68,15 @@ __poll_t iio_buffer_poll_wrapper(struct file *filp, > > struct poll_table_struct *wait); ssize_t > > iio_buffer_read_wrapper(struct file *filp, char __user *buf, > > size_t n, loff_t *f_ps); > > +ssize_t iio_buffer_write_wrapper(struct file *filp, const char __user *buf, > > + size_t n, loff_t *f_ps); > > > > int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev); > > void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev); > > > > #define iio_buffer_poll_addr (&iio_buffer_poll_wrapper) #define > > iio_buffer_read_outer_addr (&iio_buffer_read_wrapper) > > +#define iio_buffer_write_outer_addr (&iio_buffer_write_wrapper) > > > > void iio_disable_all_buffers(struct iio_dev *indio_dev); void > > iio_buffer_wakeup_poll(struct iio_dev *indio_dev); @@ -83,6 +86,7 @@ > > void iio_device_detach_buffers(struct iio_dev *indio_dev); > > > > #define iio_buffer_poll_addr NULL > > #define iio_buffer_read_outer_addr NULL > > +#define iio_buffer_write_outer_addr NULL > > > > static inline int iio_buffers_alloc_sysfs_and_mask(struct iio_dev > > *indio_dev) { diff --git a/drivers/iio/industrialio-buffer.c > > b/drivers/iio/industrialio-buffer.c > > index a95cc2da56be..7286563e6234 100644 > > --- a/drivers/iio/industrialio-buffer.c > > +++ b/drivers/iio/industrialio-buffer.c > > @@ -120,6 +120,9 @@ static ssize_t iio_buffer_read(struct file *filp, char > __user *buf, > > if (!rb || !rb->access->read) > > return -EINVAL; > > > > + if (rb->direction != IIO_BUFFER_DIRECTION_IN) > > + return -EPERM; > > + > > datum_size = rb->bytes_per_datum; > > > > /* > > @@ -161,6 +164,65 @@ static ssize_t iio_buffer_read(struct file *filp, char > __user *buf, > > return ret; > > } > > > > +static size_t iio_buffer_space_available(struct iio_buffer *buf) { > > + if (buf->access->space_available) > > + return buf->access->space_available(buf); > > + > > + return SIZE_MAX; > > +} > > + > > +static ssize_t iio_buffer_write(struct file *filp, const char __user *buf, > > + size_t n, loff_t *f_ps) > > +{ > > + struct iio_dev_buffer_pair *ib = filp->private_data; > > + struct iio_buffer *rb = ib->buffer; > > + struct iio_dev *indio_dev = ib->indio_dev; > > + DEFINE_WAIT_FUNC(wait, woken_wake_function); > > + int ret; > > + size_t written; > > + > > + if (!indio_dev->info) > > + return -ENODEV; > > + > > + if (!rb || !rb->access->write) > > + return -EINVAL; > > + > > + if (rb->direction != IIO_BUFFER_DIRECTION_OUT) > > + return -EPERM; > > + > > + written = 0; > > + add_wait_queue(&rb->pollq, &wait); > > + do { > > + if (indio_dev->info == NULL) > > + return -ENODEV; > > + > > + if (!iio_buffer_space_available(rb)) { > > + if (signal_pending(current)) { > > + ret = -ERESTARTSYS; > > + break; > > + } > > + > > + wait_woken(&wait, TASK_INTERRUPTIBLE, > > + MAX_SCHEDULE_TIMEOUT); > > + continue; > > + } > > + > > + ret = rb->access->write(rb, n - written, buf + written); > > + if (ret == 0 && (filp->f_flags & O_NONBLOCK)) > > + ret = -EAGAIN; > > + > > + if (ret > 0) { > > + written += ret; > > + if (written != n && !(filp->f_flags & O_NONBLOCK)) > > + continue; > > + } > > + } while (ret == 0); > > + remove_wait_queue(&rb->pollq, &wait); > > + > > + return ret < 0 ? ret : n; > > +} > > + > > /** > > * iio_buffer_poll() - poll the buffer to find out if it has data > > * @filp: File structure pointer for device access > > @@ -181,8 +243,18 @@ static __poll_t iio_buffer_poll(struct file *filp, > > return 0; > > > > poll_wait(filp, &rb->pollq, wait); > > - if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0)) > > - return EPOLLIN | EPOLLRDNORM; > > + > > + switch (rb->direction) { > > + case IIO_BUFFER_DIRECTION_IN: > > + if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0)) > > + return EPOLLIN | EPOLLRDNORM; > > + break; > > + case IIO_BUFFER_DIRECTION_OUT: > > + if (iio_buffer_space_available(rb)) > > + return EPOLLOUT | EPOLLWRNORM; > > + break; > > + } > > + > > return 0; > > } > > > > @@ -199,6 +271,19 @@ ssize_t iio_buffer_read_wrapper(struct file *filp, > char __user *buf, > > return iio_buffer_read(filp, buf, n, f_ps); } > > > > +ssize_t iio_buffer_write_wrapper(struct file *filp, const char __user *buf, > > + size_t n, loff_t *f_ps) > > +{ > > + struct iio_dev_buffer_pair *ib = filp->private_data; > > + struct iio_buffer *rb = ib->buffer; > > + > > + /* check if buffer was opened through new API */ > > + if (test_bit(IIO_BUSY_BIT_POS, &rb->flags)) > > + return -EBUSY; > > + > > + return iio_buffer_write(filp, buf, n, f_ps); } > > + > > __poll_t iio_buffer_poll_wrapper(struct file *filp, > > struct poll_table_struct *wait) > > { > > @@ -231,6 +316,15 @@ void iio_buffer_wakeup_poll(struct iio_dev > *indio_dev) > > } > > } > > > > +int iio_pop_from_buffer(struct iio_buffer *buffer, void *data) { > > + if (!buffer || !buffer->access || !buffer->access->remove_from) > > + return -EINVAL; > > + > > + return buffer->access->remove_from(buffer, data); } > > +EXPORT_SYMBOL_GPL(iio_pop_from_buffer); > > + > > void iio_buffer_init(struct iio_buffer *buffer) { > > INIT_LIST_HEAD(&buffer->demux_list); > > @@ -1156,6 +1250,10 @@ int iio_update_buffers(struct iio_dev > *indio_dev, > > if (insert_buffer == remove_buffer) > > return 0; > > > > + if (insert_buffer && > > + (insert_buffer->direction == IIO_BUFFER_DIRECTION_OUT)) > > + return -EINVAL; > > + > > mutex_lock(&iio_dev_opaque->info_exist_lock); > > mutex_lock(&indio_dev->mlock); > > > > @@ -1277,6 +1375,22 @@ static ssize_t > iio_dma_show_data_available(struct device *dev, > > return sysfs_emit(buf, "%zu\n", iio_buffer_data_available(buffer)); > > } > > > > +static ssize_t direction_show(struct device *dev, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer; > > + > > + switch (buffer->direction) { > > + case IIO_BUFFER_DIRECTION_IN: > > + return sprintf(buf, "in\n"); > > + case IIO_BUFFER_DIRECTION_OUT: > > + return sprintf(buf, "out\n"); > > + default: > > + return -EINVAL; > > + } > > +} > > + > > static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length, > > iio_buffer_write_length); > > static struct device_attribute dev_attr_length_ro = __ATTR(length, @@ > > -1289,12 +1403,20 @@ static struct device_attribute > dev_attr_watermark_ro = __ATTR(watermark, > > S_IRUGO, iio_buffer_show_watermark, NULL); static > > DEVICE_ATTR(data_available, S_IRUGO, > > iio_dma_show_data_available, NULL); > > +static DEVICE_ATTR_RO(direction); > > > > +/* > > + * When adding new attributes here, put the at the end, at least > > +until > > + * the code that handles the length/length_ro & > > +watermark/watermark_ro > > + * assignments gets cleaned up. Otherwise these can create some weird > > + * duplicate attributes errors under some setups. > > + */ > > static struct attribute *iio_buffer_attrs[] = { > > &dev_attr_length.attr, > > &dev_attr_enable.attr, > > &dev_attr_watermark.attr, > > &dev_attr_data_available.attr, > > + &dev_attr_direction.attr, > > }; > > > > #define to_dev_attr(_attr) container_of(_attr, struct > > device_attribute, attr) @@ -1397,6 +1519,7 @@ static const struct > file_operations iio_buffer_chrdev_fileops = { > > .owner = THIS_MODULE, > > .llseek = noop_llseek, > > .read = iio_buffer_read, > > + .write = iio_buffer_write, > > .poll = iio_buffer_poll, > > .release = iio_buffer_chrdev_release, }; diff --git > > a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c > > index 2dbb37e09b8c..537a08549a69 100644 > > --- a/drivers/iio/industrialio-core.c > > +++ b/drivers/iio/industrialio-core.c > > @@ -1822,6 +1822,7 @@ static const struct file_operations > iio_buffer_fileops = { > > .owner = THIS_MODULE, > > .llseek = noop_llseek, > > .read = iio_buffer_read_outer_addr, > > + .write = iio_buffer_write_outer_addr, > > .poll = iio_buffer_poll_addr, > > .unlocked_ioctl = iio_ioctl, > > .compat_ioctl = compat_ptr_ioctl, > > diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h > > index b6928ac5c63d..fe2e680d9b5e 100644 > > --- a/include/linux/iio/buffer.h > > +++ b/include/linux/iio/buffer.h > > @@ -11,8 +11,15 @@ > > > > struct iio_buffer; > > > > +enum iio_buffer_direction { > > + IIO_BUFFER_DIRECTION_IN, > > + IIO_BUFFER_DIRECTION_OUT, > > +}; > > + > > int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data); > > > > +int iio_pop_from_buffer(struct iio_buffer *buffer, void *data); > > + > > /** > > * iio_push_to_buffers_with_timestamp() - push data and timestamp to > buffers > > * @indio_dev: iio_dev structure for device. > > diff --git a/include/linux/iio/buffer_impl.h > > b/include/linux/iio/buffer_impl.h index 245b32918ae1..e2ca8ea23e19 > > 100644 > > --- a/include/linux/iio/buffer_impl.h > > +++ b/include/linux/iio/buffer_impl.h > > @@ -7,6 +7,7 @@ > > #ifdef CONFIG_IIO_BUFFER > > > > #include <uapi/linux/iio/buffer.h> > > +#include <linux/iio/buffer.h> > > > > struct iio_dev; > > struct iio_buffer; > > @@ -23,6 +24,10 @@ struct iio_buffer; > > * @read: try to get a specified number of bytes (must exist) > > * @data_available: indicates how much data is available for reading from > > * the buffer. > > + * @remove_from: remove scan from buffer. Drivers should calls this to > > + * remove a scan from a buffer. > > + * @write: try to write a number of bytes > > + * @space_available: returns the amount of bytes available in a > buffer > > * @request_update: if a parameter change has been marked, > update underlying > > * storage. > > * @set_bytes_per_datum:set number of bytes per datum @@ -49,6 > +54,9 > > @@ struct iio_buffer_access_funcs { > > int (*store_to)(struct iio_buffer *buffer, const void *data); > > int (*read)(struct iio_buffer *buffer, size_t n, char __user *buf); > > size_t (*data_available)(struct iio_buffer *buffer); > > + int (*remove_from)(struct iio_buffer *buffer, void *data); > > + int (*write)(struct iio_buffer *buffer, size_t n, const char __user > *buf); > > + size_t (*space_available)(struct iio_buffer *buffer); > > > > int (*request_update)(struct iio_buffer *buffer); > > > > @@ -80,6 +88,9 @@ struct iio_buffer { > > /** @bytes_per_datum: Size of individual datum including > timestamp. */ > > size_t bytes_per_datum; > > > > + /* @direction: Direction of the data stream (in/out). */ > > + enum iio_buffer_direction direction; > > + > > /** > > * @access: Buffer access functions associated with the > > * implementation.
