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-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio15
-rw-r--r--drivers/iio/industrialio-buffer.c120
-rw-r--r--drivers/iio/kfifo_buf.c11
-rw-r--r--drivers/staging/iio/accel/sca3000_ring.c4
-rw-r--r--include/linux/iio/buffer.h8
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;
};
/**