drivers: iio: dummy: Unable to add channels to simple_dummy_channel

[Bharath Vedartham]

I am trying to add the 3-axis compass data channels to the
simple_dummy_channel. I have mounted configfs and am able to load the
modules correctly. Is this the right approach? printk is not printing
anything to syslogs.

This is part of the iio_tasks in (I have finished the first 2 tasks):

https://kernelnewbies.org/IIO_tasks

output of lsmod | grep dummy:

iio_dummy              20480  2
iio_dummy_evgen        16384  1 iio_dummy

output of ls /sys/bus/iio/devices/iio:device0/:

buffer                     in_sampling_frequency
in_voltage-voltage_scale
current_timestamp_clock    in_steps_calibheight      name
dev                        in_steps_en               out_voltage0_raw
events                     in_steps_input            power
in_accel_x_calibbias       in_voltage0_offset        scan_elements
in_accel_x_calibscale      in_voltage0_raw           subsystem
in_accel_x_raw             in_voltage0_scale         trigger
in_activity_running_input  in_voltage1-voltage2_raw  uevent
in_activity_walking_input  in_voltage3-voltage4_raw

I have also put the diff.Added channel to iio_dummy_channels and added
element to enum simple_dummy_scan_elements.

Thank you,
Bharath

---
 drivers/iio/dummy/iio_simple_dummy.c | 43 ++++++++++++++++++++++++++++++++++++
 drivers/iio/dummy/iio_simple_dummy.h |  3 +++
 2 files changed, 46 insertions(+)

diff --git a/drivers/iio/dummy/iio_simple_dummy.c b/drivers/iio/dummy/iio_simple_dummy.c
index 6205247..306e0cd 100644
--- a/drivers/iio/dummy/iio_simple_dummy.c
+++ b/drivers/iio/dummy/iio_simple_dummy.c
@@ -268,6 +268,48 @@ static const struct iio_chan_spec iio_dummy_channels[] = {
 		.num_event_specs = 1,
 #endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
 	},
+	{
+		.type = IIO_MAGN,
+		.modified = 1,
+		.channel2 = IIO_MOD_X,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = DUMMY_INDEX_MAGNX,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.shift = 0,
+		},
+	},
+	{
+		.type = IIO_MAGN,
+		.modified = 1,
+		.channel2 = IIO_MOD_Y,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = DUMMY_INDEX_MAGNY,
+		.scan_type = {
+			.sign = 'u',
+			.realbits= 16,
+			.storagebits  = 16,
+			.shift = 0,
+		},
+	},
+	{
+		.type = IIO_MAGN,
+		.modified = 1,
+		.channel2 = IIO_MOD_Z,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = DUMMY_INDEX_MAGNZ,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.shift = 0,
+		},
+	},
 };
 
 /**
@@ -621,6 +663,7 @@ static struct iio_sw_device *iio_dummy_probe(const char *name)
 	/* Provide description of available channels */
 	indio_dev->channels = iio_dummy_channels;
 	indio_dev->num_channels = ARRAY_SIZE(iio_dummy_channels);
+	printk(KERN_DEBUG "No of channels are %d\n",indio_dev -> num_channels);
 
 	/*
 	 * Provide device type specific interface functions and
diff --git a/drivers/iio/dummy/iio_simple_dummy.h b/drivers/iio/dummy/iio_simple_dummy.h
index f7005c3..be6eff0 100644
--- a/drivers/iio/dummy/iio_simple_dummy.h
+++ b/drivers/iio/dummy/iio_simple_dummy.h
@@ -110,6 +110,9 @@ enum iio_simple_dummy_scan_elements {
 	DUMMY_INDEX_DIFFVOLTAGE_1M2,
 	DUMMY_INDEX_DIFFVOLTAGE_3M4,
 	DUMMY_INDEX_ACCELX,
+	DUMMY_INDEX_MAGNX,
+	DUMMY_INDEX_MAGNY,
+	DUMMY_INDEX_MAGNZ,
 };
 
 #ifdef CONFIG_IIO_SIMPLE_DUMMY_BUFFER
-- 
2.7.4