1 files changed, 96 insertions, 6 deletions

diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index 3e5bccbc9c39..61802d7947ae 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -109,6 +109,10 @@ int comedi_alloc_subdev_readback(struct comedi_subdevice *s)
 	s->readback = kcalloc(s->n_chan, sizeof(*s->readback), GFP_KERNEL);
 	if (!s->readback)
 		return -ENOMEM;
+
+	if (!s->insn_read)
+		s->insn_read = comedi_readback_insn_read;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(comedi_alloc_subdev_readback);
@@ -316,19 +320,91 @@ unsigned int comedi_bytes_per_scan(struct comedi_subdevice *s)
 	case COMEDI_SUBD_DI:
 	case COMEDI_SUBD_DO:
 	case COMEDI_SUBD_DIO:
-		bits_per_sample = 8 * bytes_per_sample(s);
-		num_samples = (cmd->chanlist_len + bits_per_sample - 1) /
-				bits_per_sample;
+		bits_per_sample = 8 * comedi_bytes_per_sample(s);
+		num_samples = DIV_ROUND_UP(cmd->scan_end_arg, bits_per_sample);
 		break;
 	default:
-		num_samples = cmd->chanlist_len;
+		num_samples = cmd->scan_end_arg;
 		break;
 	}
-	return num_samples * bytes_per_sample(s);
+	return comedi_samples_to_bytes(s, num_samples);
 }
 EXPORT_SYMBOL_GPL(comedi_bytes_per_scan);
 
 /**
+ * comedi_nscans_left - return the number of scans left in the command
+ * @s: comedi_subdevice struct
+ * @nscans: the expected number of scans
+ *
+ * If nscans is 0, the number of scans available in the async buffer will be
+ * used. Otherwise the expected number of scans will be used.
+ *
+ * If the async command has a stop_src of TRIG_COUNT, the nscans will be
+ * checked against the number of scans left in the command.
+ *
+ * The return value will then be either the expected number of scans or the
+ * number of scans remaining in the command.
+ */
+unsigned int comedi_nscans_left(struct comedi_subdevice *s,
+				unsigned int nscans)
+{
+	struct comedi_async *async = s->async;
+	struct comedi_cmd *cmd = &async->cmd;
+
+	if (nscans == 0) {
+		unsigned int nbytes = comedi_buf_read_n_available(s);
+
+		nscans = nbytes / comedi_bytes_per_scan(s);
+	}
+
+	if (cmd->stop_src == TRIG_COUNT) {
+		unsigned int scans_left = 0;
+
+		if (async->scans_done < cmd->stop_arg)
+			scans_left = cmd->stop_arg - async->scans_done;
+
+		if (nscans > scans_left)
+			nscans = scans_left;
+	}
+	return nscans;
+}
+EXPORT_SYMBOL_GPL(comedi_nscans_left);
+
+/**
+ * comedi_nsamples_left - return the number of samples left in the command
+ * @s: comedi_subdevice struct
+ * @nsamples: the expected number of samples
+ *
+ * Returns the expected number of samples of the number of samples remaining
+ * in the command.
+ */
+unsigned int comedi_nsamples_left(struct comedi_subdevice *s,
+				  unsigned int nsamples)
+{
+	struct comedi_async *async = s->async;
+	struct comedi_cmd *cmd = &async->cmd;
+
+	if (cmd->stop_src == TRIG_COUNT) {
+		/* +1 to force comedi_nscans_left() to return the scans left */
+		unsigned int nscans = (nsamples / cmd->scan_end_arg) + 1;
+		unsigned int scans_left = comedi_nscans_left(s, nscans);
+		unsigned int scan_pos =
+		    comedi_bytes_to_samples(s, async->scan_progress);
+		unsigned long long samples_left = 0;
+
+		if (scans_left) {
+			samples_left = ((unsigned long long)scans_left *
+					cmd->scan_end_arg) - scan_pos;
+		}
+
+		if (samples_left < nsamples)
+			nsamples = samples_left;
+	}
+	return nsamples;
+}
+EXPORT_SYMBOL_GPL(comedi_nsamples_left);
+
+/**
  * comedi_inc_scan_progress - update scan progress in asynchronous command
  * @s: comedi_subdevice struct
  * @num_bytes: amount of data in bytes to increment scan progress
@@ -342,10 +418,24 @@ void comedi_inc_scan_progress(struct comedi_subdevice *s,
 			      unsigned int num_bytes)
 {
 	struct comedi_async *async = s->async;
+	struct comedi_cmd *cmd = &async->cmd;
 	unsigned int scan_length = comedi_bytes_per_scan(s);
 
+	/* track the 'cur_chan' for non-SDF_PACKED subdevices */
+	if (!(s->subdev_flags & SDF_PACKED)) {
+		async->cur_chan += comedi_bytes_to_samples(s, num_bytes);
+		async->cur_chan %= cmd->chanlist_len;
+	}
+
 	async->scan_progress += num_bytes;
 	if (async->scan_progress >= scan_length) {
+		unsigned int nscans = async->scan_progress / scan_length;
+
+		if (async->scans_done < (UINT_MAX - nscans))
+			async->scans_done += nscans;
+		else
+			async->scans_done = UINT_MAX;
+
 		async->scan_progress %= scan_length;
 		async->events |= COMEDI_CB_EOS;
 	}
@@ -376,7 +466,7 @@ unsigned int comedi_handle_events(struct comedi_device *dev,
 	if (events == 0)
 		return events;
 
-	if (events & (COMEDI_CB_EOA | COMEDI_CB_ERROR | COMEDI_CB_OVERFLOW))
+	if (events & COMEDI_CB_CANCEL_MASK)
 		s->cancel(dev, s);
 
 	comedi_event(dev, s);