[PATCH 4.0 039/148] iio: adc: xilinx: Fix VREFN sign

Greg Kroah-Hartman
2015-06-03T12:20:40Z

From: Thomas Betker <thomas.betker@rohde-schwarz.com>

commit 97ffae1d30c3f6ceee67d5b0d3e540c08c13c744 upstream.

The VREFN channel is bipolar, not unipolar. Small negative values do
occur (e.g., -1mV), and unsigned conversion maps them incorrectly to
large positive values (about +1V), so fix this.

Signed-off-by: Thomas Betker <thomas.betker@rohde-schwarz.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/iio/adc/xilinx-xadc-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iio/adc/xilinx-xadc-core.c
+++ b/drivers/iio/adc/xilinx-xadc-core.c
@@ -997,7 +997,7 @@ static const struct iio_event_spec xadc_
.num_event_specs = (_alarm) ? ARRAY_SIZE(xadc_voltage_events) : 0, \
.scan_index = (_scan_index), \
.scan_type = { \
- .sign = 'u', \
+ .sign = ((_addr) == XADC_REG_VREFN) ? 's' : 'u', \
.realbits = 12, \
.storagebits = 16, \
.shift = 4, \