diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-iio | 15 | ||||
| -rw-r--r-- | drivers/iio/industrialio-buffer.c | 120 | ||||
| -rw-r--r-- | drivers/iio/kfifo_buf.c | 11 | ||||
| -rw-r--r-- | drivers/staging/iio/accel/sca3000_ring.c | 4 | ||||
| -rw-r--r-- | include/linux/iio/buffer.h | 8 |
5 files changed, 131 insertions, 27 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index 580b3f85437b..0b6f0abf3370 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -1280,3 +1280,18 @@ Contact: linux-iio@vger.kernel.org Description: Specifies number of seconds in which we compute the steps that occur in order to decide if the consumer is making steps. + +What: /sys/bus/iio/devices/iio:deviceX/buffer/watermark +KernelVersion: 4.2 +Contact: linux-iio@vger.kernel.org +Description: + A single positive integer specifying the maximum number of scan + elements to wait for. + Poll will block until the watermark is reached. + Blocking read will wait until the minimum between the requested + read amount or the low water mark is available. + Non-blocking read will retrieve the available samples from the + buffer even if there are less samples then watermark level. This + allows the application to block on poll with a timeout and read + the available samples after the timeout expires and thus have a + maximum delay guarantee. 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) diff --git a/drivers/iio/kfifo_buf.c b/drivers/iio/kfifo_buf.c index b2beea01c49b..847ca561afe0 100644 --- a/drivers/iio/kfifo_buf.c +++ b/drivers/iio/kfifo_buf.c @@ -83,9 +83,6 @@ static int iio_store_to_kfifo(struct iio_buffer *r, ret = kfifo_in(&kf->kf, data, 1); if (ret != 1) return -EBUSY; - - wake_up_interruptible_poll(&r->pollq, POLLIN | POLLRDNORM); - return 0; } @@ -109,16 +106,16 @@ static int iio_read_first_n_kfifo(struct iio_buffer *r, return copied; } -static bool iio_kfifo_buf_data_available(struct iio_buffer *r) +static size_t iio_kfifo_buf_data_available(struct iio_buffer *r) { struct iio_kfifo *kf = iio_to_kfifo(r); - bool empty; + size_t samples; mutex_lock(&kf->user_lock); - empty = kfifo_is_empty(&kf->kf); + samples = kfifo_len(&kf->kf); mutex_unlock(&kf->user_lock); - return !empty; + return samples; } static void iio_kfifo_buffer_release(struct iio_buffer *buffer) diff --git a/drivers/staging/iio/accel/sca3000_ring.c b/drivers/staging/iio/accel/sca3000_ring.c index f76a26885808..8589eade1057 100644 --- a/drivers/staging/iio/accel/sca3000_ring.c +++ b/drivers/staging/iio/accel/sca3000_ring.c @@ -129,9 +129,9 @@ error_ret: return ret ? ret : num_read; } -static bool sca3000_ring_buf_data_available(struct iio_buffer *r) +static size_t sca3000_ring_buf_data_available(struct iio_buffer *r) { - return r->stufftoread; + return r->stufftoread ? r->watermark : 0; } /** diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h index b65850a41127..eb8622b78ec9 100644 --- a/include/linux/iio/buffer.h +++ b/include/linux/iio/buffer.h @@ -21,8 +21,8 @@ struct iio_buffer; * struct iio_buffer_access_funcs - access functions for buffers. * @store_to: actually store stuff to the buffer * @read_first_n: try to get a specified number of bytes (must exist) - * @data_available: indicates whether data for reading from the buffer is - * available. + * @data_available: indicates how much data is available for reading from + * the buffer. * @request_update: if a parameter change has been marked, update underlying * storage. * @set_bytes_per_datum:set number of bytes per datum @@ -43,7 +43,7 @@ struct iio_buffer_access_funcs { int (*read_first_n)(struct iio_buffer *buffer, size_t n, char __user *buf); - bool (*data_available)(struct iio_buffer *buffer); + size_t (*data_available)(struct iio_buffer *buffer); int (*request_update)(struct iio_buffer *buffer); @@ -72,6 +72,7 @@ struct iio_buffer_access_funcs { * @demux_bounce: [INTERN] buffer for doing gather from incoming scan. * @buffer_list: [INTERN] entry in the devices list of current buffers. * @ref: [INTERN] reference count of the buffer. + * @watermark: [INTERN] number of datums to wait for poll/read. */ struct iio_buffer { int length; @@ -90,6 +91,7 @@ struct iio_buffer { void *demux_bounce; struct list_head buffer_list; struct kref ref; + unsigned int watermark; }; /** |