diff options
Diffstat (limited to 'drivers/iio/industrialio-buffer.c')
| -rw-r--r-- | drivers/iio/industrialio-buffer.c | 120 |
1 files changed, 105 insertions, 15 deletions
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index c2d5440aa226..a24b2e005eb3 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -37,11 +37,28 @@ static bool iio_buffer_is_active(struct iio_buffer *buf) return !list_empty(&buf->buffer_list); } -static bool iio_buffer_data_available(struct iio_buffer *buf) +static size_t iio_buffer_data_available(struct iio_buffer *buf) { return buf->access->data_available(buf); } +static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf, + size_t to_wait) +{ + /* wakeup if the device was unregistered */ + if (!indio_dev->info) + return true; + + /* drain the buffer if it was disabled */ + if (!iio_buffer_is_active(buf)) + to_wait = min_t(size_t, to_wait, 1); + + if (iio_buffer_data_available(buf) >= to_wait) + return true; + + return false; +} + /** * iio_buffer_read_first_n_outer() - chrdev read for buffer access * @@ -53,6 +70,8 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, { struct iio_dev *indio_dev = filp->private_data; struct iio_buffer *rb = indio_dev->buffer; + size_t datum_size; + size_t to_wait = 0; int ret; if (!indio_dev->info) @@ -61,19 +80,26 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf, if (!rb || !rb->access->read_first_n) return -EINVAL; + datum_size = rb->bytes_per_datum; + + /* + * If datum_size is 0 there will never be anything to read from the + * buffer, so signal end of file now. + */ + if (!datum_size) + return 0; + + if (!(filp->f_flags & O_NONBLOCK)) + to_wait = min_t(size_t, n / datum_size, rb->watermark); + do { - if (!iio_buffer_data_available(rb)) { - if (filp->f_flags & O_NONBLOCK) - return -EAGAIN; + ret = wait_event_interruptible(rb->pollq, + iio_buffer_ready(indio_dev, rb, to_wait)); + if (ret) + return ret; - ret = wait_event_interruptible(rb->pollq, - iio_buffer_data_available(rb) || - indio_dev->info == NULL); - if (ret) - return ret; - if (indio_dev->info == NULL) - return -ENODEV; - } + if (!indio_dev->info) + return -ENODEV; ret = rb->access->read_first_n(rb, n, buf); if (ret == 0 && (filp->f_flags & O_NONBLOCK)) @@ -96,9 +122,8 @@ unsigned int iio_buffer_poll(struct file *filp, return -ENODEV; poll_wait(filp, &rb->pollq, wait); - if (iio_buffer_data_available(rb)) + if (iio_buffer_ready(indio_dev, rb, rb->watermark)) return POLLIN | POLLRDNORM; - /* need a way of knowing if there may be enough data... */ return 0; } @@ -123,6 +148,7 @@ void iio_buffer_init(struct iio_buffer *buffer) INIT_LIST_HEAD(&buffer->buffer_list); init_waitqueue_head(&buffer->pollq); kref_init(&buffer->ref); + buffer->watermark = 1; } EXPORT_SYMBOL(iio_buffer_init); @@ -416,6 +442,11 @@ static ssize_t iio_buffer_write_length(struct device *dev, buffer->access->set_length(buffer, val); ret = 0; } + if (ret) + goto out; + if (buffer->length && buffer->length < buffer->watermark) + buffer->watermark = buffer->length; +out: mutex_unlock(&indio_dev->mlock); return ret ? ret : len; @@ -472,6 +503,7 @@ static void iio_buffer_activate(struct iio_dev *indio_dev, static void iio_buffer_deactivate(struct iio_buffer *buffer) { list_del_init(&buffer->buffer_list); + wake_up_interruptible(&buffer->pollq); iio_buffer_put(buffer); } @@ -754,16 +786,64 @@ done: static const char * const iio_scan_elements_group_name = "scan_elements"; +static ssize_t iio_buffer_show_watermark(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + struct iio_buffer *buffer = indio_dev->buffer; + + return sprintf(buf, "%u\n", buffer->watermark); +} + +static ssize_t iio_buffer_store_watermark(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + struct iio_dev *indio_dev = dev_to_iio_dev(dev); + struct iio_buffer *buffer = indio_dev->buffer; + unsigned int val; + int ret; + + ret = kstrtouint(buf, 10, &val); + if (ret) + return ret; + if (!val) + return -EINVAL; + + mutex_lock(&indio_dev->mlock); + + if (val > buffer->length) { + ret = -EINVAL; + goto out; + } + + if (iio_buffer_is_active(indio_dev->buffer)) { + ret = -EBUSY; + goto out; + } + + buffer->watermark = val; +out: + mutex_unlock(&indio_dev->mlock); + + return ret ? ret : len; +} + 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, S_IRUGO, iio_buffer_read_length, NULL); static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, iio_buffer_show_enable, iio_buffer_store_enable); +static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR, + iio_buffer_show_watermark, iio_buffer_store_watermark); static struct attribute *iio_buffer_attrs[] = { &dev_attr_length.attr, &dev_attr_enable.attr, + &dev_attr_watermark.attr, }; int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev) @@ -944,8 +1024,18 @@ static const void *iio_demux(struct iio_buffer *buffer, static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data) { const void *dataout = iio_demux(buffer, data); + int ret; + + ret = buffer->access->store_to(buffer, dataout); + if (ret) + return ret; - return buffer->access->store_to(buffer, dataout); + /* + * We can't just test for watermark to decide if we wake the poll queue + * because read may request less samples than the watermark. + */ + wake_up_interruptible_poll(&buffer->pollq, POLLIN | POLLRDNORM); + return 0; } static void iio_buffer_demux_free(struct iio_buffer *buffer) |