[RFC PATCH] hwmon: (iio_hwmon) Enable power exporting from IIO

[Michal Simek <michal.simek@xilinx.com>]

There is no reason why power channel shouldn't be exported as is done for
voltage, current, temperature and humidity.

Power channel is available on iio ina226 driver.

Tested on Xilinx ZCU102 board.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

But I don't think values are properly converted. Voltage1 is fine but the
rest is IMHO wrong. But this patch should enable power channel to be shown
which looks good.

root@zynqmp-debian:~# iio_info -a && sensors -u
Library version: 0.16 (git tag: v0.16)
Compiled with backends: local xml ip usb serial
Using auto-detected IIO context at URI "local:"
IIO context created with local backend.
Backend version: 0.16 (git tag: v0.16)
Backend description string: Linux zynqmp-debian 5.3.0-rc4-00004-ga7ca33daed22-dirty #41 SMP PREEMPT Mon Aug 12 15:06:58 CEST 2019 aarch64
IIO context has 1 attributes:
	local,kernel: 5.3.0-rc4-00004-ga7ca33daed22-dirty
IIO context has 1 devices:
	iio:device0: ina226 (buffer capable)
		9 channels found:
			voltage0:  (input, index: 0, format: le:U16/16>>0)
			3 channel-specific attributes found:
				attr  0: integration_time value: 0.001100
				attr  1: raw value: 70
				attr  2: scale value: 0.002500000
			voltage1:  (input, index: 1, format: le:U16/16>>0)
			3 channel-specific attributes found:
				attr  0: integration_time value: 0.001100
				attr  1: raw value: 958
				attr  2: scale value: 1.250000000
			power2:  (input, index: 2, format: le:U16/16>>0)
			2 channel-specific attributes found:
				attr  0: raw value: 3
				attr  1: scale value: 0.006250000
			current3:  (input, index: 3, format: le:U16/16>>0)
			2 channel-specific attributes found:
				attr  0: raw value: 70
				attr  1: scale value: 0.000250000
			timestamp:  (input, index: 4, format: le:S64/64>>0)
			allow:  (input)
			1 channel-specific attributes found:
				attr  0: async_readout value: 0
			oversampling:  (input)
			1 channel-specific attributes found:
				attr  0: ratio value: 4
			sampling:  (input)
			1 channel-specific attributes found:
				attr  0: frequency value: 114
			shunt:  (input)
			1 channel-specific attributes found:
				attr  0: resistor value: 10.000000000
		2 device-specific attributes found:
				attr  0: current_timestamp_clock value: realtime

				attr  1: integration_time_available value: 0.000140 0.000204 0.000332 0.000588 0.001100 0.002116 0.004156 0.008244
		2 buffer-specific attributes found:
				attr  0: data_available value: 0
				attr  1: watermark value: 1
		1 debug attributes found:
				debug attr  0: direct_reg_access value: 0x4327
ina226_fourth-isa-0000
Adapter: ISA adapter
in1:
  in1_input: 0.000
in2:
  in2_input: 1.198
power1:
  power1_input: 0.000
curr1:
  curr1_input: 0.000
---
 drivers/hwmon/iio_hwmon.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/iio_hwmon.c b/drivers/hwmon/iio_hwmon.c
index f1c2d5faedf0..aedb95fa24e3 100644
--- a/drivers/hwmon/iio_hwmon.c
+++ b/drivers/hwmon/iio_hwmon.c
@@ -59,7 +59,7 @@ static int iio_hwmon_probe(struct platform_device *pdev)
 	struct iio_hwmon_state *st;
 	struct sensor_device_attribute *a;
 	int ret, i;
-	int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1;
+	int in_i = 1, temp_i = 1, curr_i = 1, humidity_i = 1, power_i = 1;
 	enum iio_chan_type type;
 	struct iio_channel *channels;
 	struct device *hwmon_dev;
@@ -114,6 +114,10 @@ static int iio_hwmon_probe(struct platform_device *pdev)
 			n = curr_i++;
 			prefix = "curr";
 			break;
+		case IIO_POWER:
+			n = power_i++;
+			prefix = "power";
+			break;
 		case IIO_HUMIDITYRELATIVE:
 			n = humidity_i++;
 			prefix = "humidity";
-- 
2.17.1