fd-zio: handle a negative coarse readout

3465f98f · Alessandro Rubini · 972b0f68 · 3465f98f
Commit 3465f98f authored May 09, 2012 by Alessandro Rubini
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fd-zio.c fd-zio.c +15 -0

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--- a/fd-zio.c
+++ b/fd-zio.c
@@ -441,6 +441,19 @@ static int fd_read_fifo(struct spec_fd *fd, struct zio_channel *chan)
 	t.channel = FD_TSBR_FID_CHANNEL_R(reg);
 	t.seq_id = FD_TSBR_FID_SEQID_R(reg);

+	/* The coarse count may be negative, because of how it works */
+	if (t.coarse & (1<<27)) { // coarse is 28 bits
+		printk("%i (%x)\n", t.coarse, t.coarse);
+		/* we may get 0xfff.ffef..0xffff.ffff -- 125M == 0x773.5940 */
+		t.coarse += 125000000;
+		t.coarse &= 0xfffffff;
+		t.utc--;
+	} else if(t.coarse > 125000000) {
+		printk("%i (%x)\n", t.coarse, t.coarse);
+		t.coarse -= 125000000;
+		t.utc++;
+	}
+
 	fd_ts_sub(&t, fd->calib.tdc_zero_offset);

 	/* The input data is written to attribute values in the active block. */
@@ -454,6 +467,8 @@ static int fd_read_fifo(struct spec_fd *fd, struct zio_channel *chan)
 	v[FD_ATTR_TDC_CHAN]	= t.channel;
 	v[FD_ATTR_TDC_OFFSET]	= fd->calib.tdc_zero_offset;

+
+
 	__fd_apply_offset(v + FD_ATTR_TDC_UTC_H, fd->calib.tdc_user_offset);

 	/* We also need a copy within the device, so sysfs can read it */