[PATCH 2/2] Input: adc-joystick: Handle inverted axes

[Chris Morgan <macroalpha82@gmail.com>]

From: Chris Morgan <macromorgan@hotmail.com>

When one or more axes are inverted, (where min > max), normalize the
data so that min < max and call a helper function to invert the
values reported to the input stack.

This ensures we can continue defining the device correctly in the
device tree while not breaking downstream assumptions that min is
always less than max.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
---
 drivers/input/joystick/adc-joystick.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/input/joystick/adc-joystick.c b/drivers/input/joystick/adc-joystick.c
index c0deff5d4282..4e8d446987b6 100644
--- a/drivers/input/joystick/adc-joystick.c
+++ b/drivers/input/joystick/adc-joystick.c
@@ -18,6 +18,7 @@ struct adc_joystick_axis {
 	s32 range[2];
 	s32 fuzz;
 	s32 flat;
+	bool inverted;
 };
 
 struct adc_joystick {
@@ -38,6 +39,8 @@ static void adc_joystick_poll(struct input_dev *input)
 		ret = iio_read_channel_raw(&joy->chans[i], &val);
 		if (ret < 0)
 			return;
+		if (joy->axes[i].inverted)
+			val = input_invert_abs(input, i, val);
 		input_report_abs(input, joy->axes[i].code, val);
 	}
 	input_sync(input);
@@ -86,6 +89,8 @@ static int adc_joystick_handle(const void *data, void *private)
 			val = sign_extend32(val, msb);
 		else
 			val &= GENMASK(msb, 0);
+		if (joy->axes[i].inverted)
+			val = input_invert_abs(joy->input, i, val);
 		input_report_abs(joy->input, joy->axes[i].code, val);
 	}
 
@@ -168,11 +173,17 @@ static int adc_joystick_set_axes(struct device *dev, struct adc_joystick *joy)
 			goto err_fwnode_put;
 		}
 
+		if (axes[i].range[0] > axes[i].range[1]) {
+			dev_dbg(dev, "abs-axis %d inverted\n", i);
+			axes[i].inverted = 1;
+		}
+
 		fwnode_property_read_u32(child, "abs-fuzz", &axes[i].fuzz);
 		fwnode_property_read_u32(child, "abs-flat", &axes[i].flat);
 
 		input_set_abs_params(joy->input, axes[i].code,
-				     axes[i].range[0], axes[i].range[1],
+				     min_array(axes[i].range, 2),
+				     max_array(axes[i].range, 2),
 				     axes[i].fuzz, axes[i].flat);
 		input_set_capability(joy->input, EV_ABS, axes[i].code);
 	}
-- 
2.34.1