[PATCH 0/3] Add support for BMC150 magnetometer

[PATCH 0/3] Add support for BMC150 magnetometer

[Irina Tirdea]

This adds support for Bosch BMC150 magnetometer.

Irina Tirdea (3):
  iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS
  iio: magn: Add support for BMC150 magnetometer
  iio: magn: bmc150_magn: Add devicetree binding documentation

 Documentation/ABI/testing/sysfs-bus-iio            |   10 +
 .../bindings/iio/magnetometer/bmc150_magn.txt      |   20 +
 drivers/iio/industrialio-core.c                    |    1 +
 drivers/iio/magnetometer/Kconfig                   |   14 +
 drivers/iio/magnetometer/Makefile                  |    2 +
 drivers/iio/magnetometer/bmc150_magn.c             | 1060 ++++++++++++++++++++
 include/linux/iio/iio.h                            |    1 +
 7 files changed, 1108 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
 create mode 100644 drivers/iio/magnetometer/bmc150_magn.c

-- 
1.9.1

[PATCH 1/3] iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS

[Irina Tirdea]

Some magnetometers can perform a number of repetitions in HW
for each measurement to increase accuracy. One example is
Bosch BMC150:
http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.

Introduce an interface to set the number of repetitions
for these devices.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-iio | 10 ++++++++++
 drivers/iio/industrialio-core.c         |  1 +
 include/linux/iio/iio.h                 |  1 +
 3 files changed, 12 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 866b4ec..74c1444 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -1375,3 +1375,13 @@ Description:
 		The emissivity ratio of the surface in the field of view of the
 		contactless temperature sensor.  Emissivity varies from 0 to 1,
 		with 1 being the emissivity of a black body.
+
+What:		/sys/bus/iio/devices/iio:deviceX/in_magn_x_calibrepetitions
+What:		/sys/bus/iio/devices/iio:deviceX/in_magn_y_calibrepetitions
+What:		/sys/bus/iio/devices/iio:deviceX/in_magn_z_calibrepetitions
+KernelVersion:	4.2
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Hardware applied number of repetitions for acquiring one
+		data point. The HW will do <type>[_name]_calibrepetitions
+		measurements and return the average value as output data.
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 7c98bc1..9e0da7f 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -129,6 +129,7 @@ static const char * const iio_chan_info_postfix[] = {
 	[IIO_CHAN_INFO_DEBOUNCE_COUNT] = "debounce_count",
 	[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
 	[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
+	[IIO_CHAN_INFO_CALIBREPETITIONS] = "calibrepetitions",
 };
 
 /**
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index b1e46ae..07fbfb2 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -44,6 +44,7 @@ enum iio_chan_info_enum {
 	IIO_CHAN_INFO_DEBOUNCE_COUNT,
 	IIO_CHAN_INFO_DEBOUNCE_TIME,
 	IIO_CHAN_INFO_CALIBEMISSIVITY,
+	IIO_CHAN_INFO_CALIBREPETITIONS,
 };
 
 enum iio_shared_by {
-- 
1.9.1

Re: [PATCH 1/3] iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS

[Jonathan Cameron]

On 17/04/15 11:50, Irina Tirdea wrote:
> Some magnetometers can perform a number of repetitions in HW
> for each measurement to increase accuracy. One example is
> Bosch BMC150:
> http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
> 
> Introduce an interface to set the number of repetitions
> for these devices.
> 
> Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 10 ++++++++++
>  drivers/iio/industrialio-core.c         |  1 +
>  include/linux/iio/iio.h                 |  1 +
>  3 files changed, 12 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index 866b4ec..74c1444 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -1375,3 +1375,13 @@ Description:
>  		The emissivity ratio of the surface in the field of view of the
>  		contactless temperature sensor.  Emissivity varies from 0 to 1,
>  		with 1 being the emissivity of a black body.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_x_calibrepetitions
> +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_y_calibrepetitions
> +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_z_calibrepetitions
> +KernelVersion:	4.2
> +Contact:	linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> +Description:
> +		Hardware applied number of repetitions for acquiring one
> +		data point. The HW will do <type>[_name]_calibrepetitions
> +		measurements and return the average value as output data.
This is an interesting way of naming what is often referred to as oversampling.
I'd like to get some other opinions on naming before we go with the ABI for this..

We do have one driver in staging exporting oversampling_ratio which is probably
the same thing, but that ABI was never standardized so I have no problem with
ignoring that one case.  A couple of other drivers provide oversampling control
via platform data.   We must make sure we give a sensible default for this.

There is also the interesting question of whether sampling_frequency applies
before or after this...  I'd argue after, but again would like more opinions
before we dictate that.  However, whatever we choose should definitely be
documented here!

> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> index 7c98bc1..9e0da7f 100644
> --- a/drivers/iio/industrialio-core.c
> +++ b/drivers/iio/industrialio-core.c
> @@ -129,6 +129,7 @@ static const char * const iio_chan_info_postfix[] = {
>  	[IIO_CHAN_INFO_DEBOUNCE_COUNT] = "debounce_count",
>  	[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
>  	[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
> +	[IIO_CHAN_INFO_CALIBREPETITIONS] = "calibrepetitions",
>  };
>  
>  /**
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index b1e46ae..07fbfb2 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -44,6 +44,7 @@ enum iio_chan_info_enum {
>  	IIO_CHAN_INFO_DEBOUNCE_COUNT,
>  	IIO_CHAN_INFO_DEBOUNCE_TIME,
>  	IIO_CHAN_INFO_CALIBEMISSIVITY,
> +	IIO_CHAN_INFO_CALIBREPETITIONS,
>  };
>  
>  enum iio_shared_by {
> 

RE: [PATCH 1/3] iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS

[Tirdea, Irina]

> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23@kernel.org]
> Sent: 18 April, 2015 19:47
> To: Tirdea, Irina; linux-iio@vger.kernel.org; devicetree@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org; Hartmut Knaack; Lars-Peter Clausen; Peter Meerwald; Rob Herring; Pawel Moll; Mark Rutland; Ian
> Campbell; Kumar Gala
> Subject: Re: [PATCH 1/3] iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS
> 
> On 17/04/15 11:50, Irina Tirdea wrote:
> > Some magnetometers can perform a number of repetitions in HW
> > for each measurement to increase accuracy. One example is
> > Bosch BMC150:
> > http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
> >
> > Introduce an interface to set the number of repetitions
> > for these devices.
> >
> > Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
> > ---
> >  Documentation/ABI/testing/sysfs-bus-iio | 10 ++++++++++
> >  drivers/iio/industrialio-core.c         |  1 +
> >  include/linux/iio/iio.h                 |  1 +
> >  3 files changed, 12 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> > index 866b4ec..74c1444 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-iio
> > +++ b/Documentation/ABI/testing/sysfs-bus-iio
> > @@ -1375,3 +1375,13 @@ Description:
> >  		The emissivity ratio of the surface in the field of view of the
> >  		contactless temperature sensor.  Emissivity varies from 0 to 1,
> >  		with 1 being the emissivity of a black body.
> > +
> > +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_x_calibrepetitions
> > +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_y_calibrepetitions
> > +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_z_calibrepetitions
> > +KernelVersion:	4.2
> > +Contact:	linux-iio@vger.kernel.org
> > +Description:
> > +		Hardware applied number of repetitions for acquiring one
> > +		data point. The HW will do <type>[_name]_calibrepetitions
> > +		measurements and return the average value as output data.
> This is an interesting way of naming what is often referred to as oversampling.
> I'd like to get some other opinions on naming before we go with the ABI for this..
> 
> We do have one driver in staging exporting oversampling_ratio which is probably
> the same thing, but that ABI was never standardized so I have no problem with
> ignoring that one case.  A couple of other drivers provide oversampling control
> via platform data.   We must make sure we give a sensible default for this.
> 
I didn't know about the oversampling_ratio. I used "repetitions" because Bosch calls them so
in the datasheet.
However, I think oversampling_ratio is a better name since it suggests a
connection with sampling. I will change it to oversampling_ratio in v2 and then
wait for more opinions on this.

> There is also the interesting question of whether sampling_frequency applies
> before or after this...  I'd argue after, but again would like more opinions
> before we dictate that.  However, whatever we choose should definitely be
> documented here!
> 
The HW sees the sampling_frequency as the frequency the user sees, so it does not take into
account the oversampling_ratio: each value resulted after oversampling_ratio repetitions is
considered one sample for the sampling_frequency. However, I am not sure how other
devices handle this so more opinions on this would be useful.

Looking more into the oversampling ratio from BMC150, seems there are some
sampling limitations I missed the first time: when setting a certain value for x/y/z repetitions,
not all sampling rates are available.  I am going to fix this in v2 by not allowing invalid
sampling rates once a certain value for oversampling_ratio is set.

Thanks,
Irina

> > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> > index 7c98bc1..9e0da7f 100644
> > --- a/drivers/iio/industrialio-core.c
> > +++ b/drivers/iio/industrialio-core.c
> > @@ -129,6 +129,7 @@ static const char * const iio_chan_info_postfix[] = {
> >  	[IIO_CHAN_INFO_DEBOUNCE_COUNT] = "debounce_count",
> >  	[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
> >  	[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
> > +	[IIO_CHAN_INFO_CALIBREPETITIONS] = "calibrepetitions",
> >  };
> >
> >  /**
> > diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> > index b1e46ae..07fbfb2 100644
> > --- a/include/linux/iio/iio.h
> > +++ b/include/linux/iio/iio.h
> > @@ -44,6 +44,7 @@ enum iio_chan_info_enum {
> >  	IIO_CHAN_INFO_DEBOUNCE_COUNT,
> >  	IIO_CHAN_INFO_DEBOUNCE_TIME,
> >  	IIO_CHAN_INFO_CALIBEMISSIVITY,
> > +	IIO_CHAN_INFO_CALIBREPETITIONS,
> >  };
> >
> >  enum iio_shared_by {
> >

Re: [PATCH 1/3] iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS

[Jonathan Cameron]

On 22/04/15 12:33, Tirdea, Irina wrote:
> 
> 
>> -----Original Message-----
>> From: Jonathan Cameron [mailto:jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
>> Sent: 18 April, 2015 19:47
>> To: Tirdea, Irina; linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Hartmut Knaack; Lars-Peter Clausen; Peter Meerwald; Rob Herring; Pawel Moll; Mark Rutland; Ian
>> Campbell; Kumar Gala
>> Subject: Re: [PATCH 1/3] iio: core: Introduce IIO_CHAN_INFO_CALIBREPETITIONS
>>
>> On 17/04/15 11:50, Irina Tirdea wrote:
>>> Some magnetometers can perform a number of repetitions in HW
>>> for each measurement to increase accuracy. One example is
>>> Bosch BMC150:
>>> http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
>>>
>>> Introduce an interface to set the number of repetitions
>>> for these devices.
>>>
>>> Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>>> ---
>>>  Documentation/ABI/testing/sysfs-bus-iio | 10 ++++++++++
>>>  drivers/iio/industrialio-core.c         |  1 +
>>>  include/linux/iio/iio.h                 |  1 +
>>>  3 files changed, 12 insertions(+)
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
>>> index 866b4ec..74c1444 100644
>>> --- a/Documentation/ABI/testing/sysfs-bus-iio
>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio
>>> @@ -1375,3 +1375,13 @@ Description:
>>>  		The emissivity ratio of the surface in the field of view of the
>>>  		contactless temperature sensor.  Emissivity varies from 0 to 1,
>>>  		with 1 being the emissivity of a black body.
>>> +
>>> +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_x_calibrepetitions
>>> +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_y_calibrepetitions
>>> +What:		/sys/bus/iio/devices/iio:deviceX/in_magn_z_calibrepetitions
>>> +KernelVersion:	4.2
>>> +Contact:	linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> +Description:
>>> +		Hardware applied number of repetitions for acquiring one
>>> +		data point. The HW will do <type>[_name]_calibrepetitions
>>> +		measurements and return the average value as output data.
>> This is an interesting way of naming what is often referred to as oversampling.
>> I'd like to get some other opinions on naming before we go with the ABI for this..
>>
>> We do have one driver in staging exporting oversampling_ratio which is probably
>> the same thing, but that ABI was never standardized so I have no problem with
>> ignoring that one case.  A couple of other drivers provide oversampling control
>> via platform data.   We must make sure we give a sensible default for this.
>>
> I didn't know about the oversampling_ratio. I used "repetitions" because Bosch calls them so
> in the datasheet.
> However, I think oversampling_ratio is a better name since it suggests a
> connection with sampling. I will change it to oversampling_ratio in v2 and then
> wait for more opinions on this.
> 
>> There is also the interesting question of whether sampling_frequency applies
>> before or after this...  I'd argue after, but again would like more opinions
>> before we dictate that.  However, whatever we choose should definitely be
>> documented here!
>>
> The HW sees the sampling_frequency as the frequency the user sees, so it does not take into
> account the oversampling_ratio: each value resulted after oversampling_ratio repetitions is
> considered one sample for the sampling_frequency. However, I am not sure how other
> devices handle this so more opinions on this would be useful.
That description works for me. Put something like this in the docs and
hopefully we will be consistent across devices.
> 
> Looking more into the oversampling ratio from BMC150, seems there are some
> sampling limitations I missed the first time: when setting a certain value for x/y/z repetitions,
> not all sampling rates are available.  I am going to fix this in v2 by not allowing invalid
> sampling rates once a certain value for oversampling_ratio is set.
Cool. As long as you update sampling_frequency_available that's fine.

J
> 
> Thanks,
> Irina
> 
>>> diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
>>> index 7c98bc1..9e0da7f 100644
>>> --- a/drivers/iio/industrialio-core.c
>>> +++ b/drivers/iio/industrialio-core.c
>>> @@ -129,6 +129,7 @@ static const char * const iio_chan_info_postfix[] = {
>>>  	[IIO_CHAN_INFO_DEBOUNCE_COUNT] = "debounce_count",
>>>  	[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
>>>  	[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
>>> +	[IIO_CHAN_INFO_CALIBREPETITIONS] = "calibrepetitions",
>>>  };
>>>
>>>  /**
>>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
>>> index b1e46ae..07fbfb2 100644
>>> --- a/include/linux/iio/iio.h
>>> +++ b/include/linux/iio/iio.h
>>> @@ -44,6 +44,7 @@ enum iio_chan_info_enum {
>>>  	IIO_CHAN_INFO_DEBOUNCE_COUNT,
>>>  	IIO_CHAN_INFO_DEBOUNCE_TIME,
>>>  	IIO_CHAN_INFO_CALIBEMISSIVITY,
>>> +	IIO_CHAN_INFO_CALIBREPETITIONS,
>>>  };
>>>
>>>  enum iio_shared_by {
>>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

[PATCH 2/3] iio: magn: Add support for BMC150 magnetometer

[Irina Tirdea]

Add support for the Bosh BMC150 Magnetometer.
The specification can be downloaded from:
http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
The chip contains both an accelerometer and a magnetometer.
This patch adds support only for the magnetometer part.

The temperature compensation formulas are based on bmm050_api.c
authored by contact-oifgY8usX4GOK76mbL0HZ+jAqQFK86Wj@public.gmane.org

Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/iio/magnetometer/Kconfig       |   14 +
 drivers/iio/magnetometer/Makefile      |    2 +
 drivers/iio/magnetometer/bmc150_magn.c | 1060 ++++++++++++++++++++++++++++++++
 3 files changed, 1076 insertions(+)
 create mode 100644 drivers/iio/magnetometer/bmc150_magn.c

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index a5d6de7..008baca 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -76,4 +76,18 @@ config IIO_ST_MAGN_SPI_3AXIS
 	depends on IIO_ST_MAGN_3AXIS
 	depends on IIO_ST_SENSORS_SPI
 
+config BMC150_MAGN
+	tristate "Bosch BMC150 Magnetometer Driver"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for the BMC150 magnetometer.
+
+	  Currently this only supports the device via an i2c interface.
+
+	  This is a combo module with both accelerometer and magnetometer.
+	  This driver is only implementing magnetometer part, which has
+	  its own address and register map.
+
 endmenu
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index 0f5d3c9..e2c3459 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -13,3 +13,5 @@ st_magn-$(CONFIG_IIO_BUFFER) += st_magn_buffer.o
 
 obj-$(CONFIG_IIO_ST_MAGN_I2C_3AXIS) += st_magn_i2c.o
 obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
+
+obj-$(CONFIG_BMC150_MAGN) += bmc150_magn.o
diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
new file mode 100644
index 0000000..e970a0c
--- /dev/null
+++ b/drivers/iio/magnetometer/bmc150_magn.c
@@ -0,0 +1,1060 @@
+/*
+ * Bosch BMC150 three-axis magnetic field sensor driver
+ *
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This code is based on bmm050_api.c authored by contact-oifgY8usX4GOK76mbL0HZ0EOCMrvLtNR@public.gmane.org:
+ *
+ * (C) Copyright 2011~2014 Bosch Sensortec GmbH All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/events.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/regmap.h>
+
+#define BMC150_MAGN_DRV_NAME			"bmc150_magn"
+#define BMC150_MAGN_IRQ_NAME			"bmc150_magn_event"
+#define BMC150_MAGN_GPIO_INT			"interrupt"
+
+#define BMC150_MAGN_REG_CHIP_ID			0x40
+#define BMC150_MAGN_CHIP_ID_VAL			0x32
+
+#define BMC150_MAGN_REG_X_L			0x42
+#define BMC150_MAGN_REG_X_M			0x43
+#define BMC150_MAGN_REG_Y_L			0x44
+#define BMC150_MAGN_REG_Y_M			0x45
+#define BMC150_MAGN_SHIFT_XY_L			3
+#define BMC150_MAGN_REG_Z_L			0x46
+#define BMC150_MAGN_REG_Z_M			0x47
+#define BMC150_MAGN_SHIFT_Z_L			1
+#define BMC150_MAGN_REG_RHALL_L			0x48
+#define BMC150_MAGN_REG_RHALL_M			0x49
+#define BMC150_MAGN_SHIFT_RHALL_L		2
+
+#define BMC150_MAGN_REG_INT_STATUS		0x4A
+
+#define BMC150_MAGN_REG_POWER			0x4B
+#define BMC150_MAGN_MASK_POWER_CTL		BIT(0)
+
+#define BMC150_MAGN_REG_OPMODE_ODR		0x4C
+#define BMC150_MAGN_MASK_OPMODE			GENMASK(2, 1)
+#define BMC150_MAGN_SHIFT_OPMODE		1
+#define BMC150_MAGN_MODE_NORMAL			0x00
+#define BMC150_MAGN_MODE_FORCED			0x01
+#define BMC150_MAGN_MODE_SLEEP			0x03
+#define BMC150_MAGN_MASK_ODR			GENMASK(5, 3)
+#define BMC150_MAGN_SHIFT_ODR			3
+
+#define BMC150_MAGN_REG_INT			0x4D
+
+#define BMC150_MAGN_REG_INT_DRDY		0x4E
+#define BMC150_MAGN_MASK_DRDY_EN		BIT(7)
+#define BMC150_MAGN_SHIFT_DRDY_EN		7
+#define BMC150_MAGN_MASK_DRDY_INT3		BIT(6)
+#define BMC150_MAGN_MASK_DRDY_Z_EN		BIT(5)
+#define BMC150_MAGN_MASK_DRDY_Y_EN		BIT(4)
+#define BMC150_MAGN_MASK_DRDY_X_EN		BIT(3)
+#define BMC150_MAGN_MASK_DRDY_DR_POLARITY	BIT(2)
+#define BMC150_MAGN_MASK_DRDY_LATCHING		BIT(1)
+#define BMC150_MAGN_MASK_DRDY_INT3_POLARITY	BIT(0)
+
+#define BMC150_MAGN_REG_LOW_THRESH		0x4F
+#define BMC150_MAGN_REG_HIGH_THRESH		0x50
+#define BMC150_MAGN_REG_REP_XY			0x51
+#define BMC150_MAGN_REG_REP_Z			0x52
+
+#define BMC150_MAGN_REG_TRIM_START		0x5D
+#define BMC150_MAGN_REG_TRIM_END		0x71
+
+#define BMC150_MAGN_XY_OVERFLOW_VAL		-4096
+#define BMC150_MAGN_Z_OVERFLOW_VAL		-16384
+
+/* Time from SUSPEND to SLEEP */
+#define BMC150_MAGN_START_UP_TIME_MS		3
+
+#define BMC150_MAGN_AUTO_SUSPEND_DELAY_MS	2000
+
+#define BMC150_MAGN_REGVAL_TO_REPXY(regval) (((regval) * 2) + 1)
+#define BMC150_MAGN_REGVAL_TO_REPZ(regval) ((regval) + 1)
+#define BMC150_MAGN_REPXY_TO_REGVAL(rep) (((rep) - 1) / 2)
+#define BMC150_MAGN_REPZ_TO_REGVAL(rep) ((rep) - 1)
+
+enum bmc150_magn_axis {
+	AXIS_X,
+	AXIS_Y,
+	AXIS_Z,
+	RHALL,
+	AXIS_XYZ_MAX = RHALL,
+	AXIS_XYZR_MAX,
+};
+
+enum bmc150_magn_power_modes {
+	BMC150_MAGN_POWER_MODE_SUSPEND,
+	BMC150_MAGN_POWER_MODE_SLEEP,
+	BMC150_MAGN_POWER_MODE_NORMAL,
+};
+
+struct bmc150_magn_trim_regs {
+	s8 x1;
+	s8 y1;
+	__le16 reserved1;
+	u8 reserved2;
+	__le16 z4;
+	s8 x2;
+	s8 y2;
+	__le16 reserved3;
+	__le16 z2;
+	__le16 z1;
+	__le16 xyz1;
+	__le16 z3;
+	s8 xy2;
+	u8 xy1;
+} __packed;
+
+struct bmc150_magn_data {
+	struct i2c_client *client;
+	/*
+	 * 1. Protect this structure.
+	 * 2. Serialize sequences that power on/off the device and access HW.
+	 */
+	struct mutex mutex;
+	struct regmap *regmap;
+	s32 *buffer;
+	struct iio_trigger *dready_trig;
+	bool dready_trigger_on;
+};
+
+static const struct {
+	int freq;
+	u8 reg_val;
+} bmc150_magn_samp_freq_table[] = { {10, 0x00},
+				    {2, 0x01},
+				    {6, 0x02},
+				    {8, 0x03},
+				    {15, 0x04},
+				    {20, 0x05},
+				    {25, 0x06},
+				    {30, 0x07} };
+
+enum bmc150_magn_presets {
+	LOW_POWER_PRESET,
+	REGULAR_PRESET,
+	ENHANCED_REGULAR_PRESET,
+	HIGH_ACCURACY_PRESET
+};
+
+static const struct bmc150_magn_preset {
+	u8 rep_xy;
+	u8 rep_z;
+	u8 odr;
+} bmc150_magn_presets_table[] = {
+	[LOW_POWER_PRESET] = {3, 3, 10},
+	[REGULAR_PRESET] =  {9, 15, 10},
+	[ENHANCED_REGULAR_PRESET] =  {15, 27, 10},
+	[HIGH_ACCURACY_PRESET] =  {47, 83, 20},
+};
+
+#define BMC150_MAGN_DEFAULT_PRESET REGULAR_PRESET
+
+static bool bmc150_magn_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BMC150_MAGN_REG_POWER:
+	case BMC150_MAGN_REG_OPMODE_ODR:
+	case BMC150_MAGN_REG_INT:
+	case BMC150_MAGN_REG_INT_DRDY:
+	case BMC150_MAGN_REG_LOW_THRESH:
+	case BMC150_MAGN_REG_HIGH_THRESH:
+	case BMC150_MAGN_REG_REP_XY:
+	case BMC150_MAGN_REG_REP_Z:
+		return true;
+	default:
+		return false;
+	};
+}
+
+static bool bmc150_magn_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BMC150_MAGN_REG_X_L:
+	case BMC150_MAGN_REG_X_M:
+	case BMC150_MAGN_REG_Y_L:
+	case BMC150_MAGN_REG_Y_M:
+	case BMC150_MAGN_REG_Z_L:
+	case BMC150_MAGN_REG_Z_M:
+	case BMC150_MAGN_REG_RHALL_L:
+	case BMC150_MAGN_REG_RHALL_M:
+	case BMC150_MAGN_REG_INT_STATUS:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config bmc150_magn_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = BMC150_MAGN_REG_TRIM_END,
+	.cache_type = REGCACHE_RBTREE,
+
+	.writeable_reg = bmc150_magn_is_writeable_reg,
+	.volatile_reg = bmc150_magn_is_volatile_reg,
+};
+
+static void bmc150_magn_sleep(int sleep_time_ms)
+{
+	if (sleep_time_ms < 20)
+		usleep_range(sleep_time_ms * 1000, 20000);
+	else
+		msleep_interruptible(sleep_time_ms);
+}
+
+static int bmc150_magn_set_power_mode(struct bmc150_magn_data *data,
+				      enum bmc150_magn_power_modes mode,
+				      bool state)
+{
+	int ret;
+
+	switch (mode) {
+	case BMC150_MAGN_POWER_MODE_SUSPEND:
+		ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_POWER,
+					 BMC150_MAGN_MASK_POWER_CTL, !state);
+		if (ret < 0)
+			return ret;
+		bmc150_magn_sleep(BMC150_MAGN_START_UP_TIME_MS);
+		return 0;
+	case BMC150_MAGN_POWER_MODE_SLEEP:
+		return regmap_update_bits(data->regmap,
+					  BMC150_MAGN_REG_OPMODE_ODR,
+					  BMC150_MAGN_MASK_OPMODE,
+					  BMC150_MAGN_MODE_SLEEP <<
+					  BMC150_MAGN_SHIFT_OPMODE);
+	case BMC150_MAGN_POWER_MODE_NORMAL:
+		return regmap_update_bits(data->regmap,
+					  BMC150_MAGN_REG_OPMODE_ODR,
+					  BMC150_MAGN_MASK_OPMODE,
+					  BMC150_MAGN_MODE_NORMAL <<
+					  BMC150_MAGN_SHIFT_OPMODE);
+	}
+
+	return -EINVAL;
+}
+
+static int bmc150_magn_set_power_state(struct bmc150_magn_data *data, bool on)
+{
+#ifdef CONFIG_PM
+	int ret;
+
+	if (on) {
+		ret = pm_runtime_get_sync(&data->client->dev);
+	} else {
+		pm_runtime_mark_last_busy(&data->client->dev);
+		ret = pm_runtime_put_autosuspend(&data->client->dev);
+	}
+
+	if (ret < 0) {
+		dev_err(&data->client->dev,
+			"failed to change power state to %d\n", on);
+		if (on)
+			pm_runtime_put_noidle(&data->client->dev);
+
+		return ret;
+	}
+#endif
+
+	return 0;
+}
+
+static int bmc150_magn_get_odr(struct bmc150_magn_data *data, int *val)
+{
+	int ret, reg_val;
+	u8 i, odr_val;
+
+	ret = regmap_read(data->regmap, BMC150_MAGN_REG_OPMODE_ODR, &reg_val);
+	if (ret < 0)
+		return ret;
+	odr_val = (reg_val & BMC150_MAGN_MASK_ODR) >> BMC150_MAGN_SHIFT_ODR;
+
+	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++)
+		if (bmc150_magn_samp_freq_table[i].reg_val == odr_val) {
+			*val = bmc150_magn_samp_freq_table[i].freq;
+			return 0;
+		}
+
+	return -EINVAL;
+}
+
+static int bmc150_magn_set_odr(struct bmc150_magn_data *data, int val)
+{
+	int ret;
+	u8 i;
+
+	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++) {
+		if (bmc150_magn_samp_freq_table[i].freq == val) {
+			ret = regmap_update_bits(data->regmap,
+						 BMC150_MAGN_REG_OPMODE_ODR,
+						 BMC150_MAGN_MASK_ODR,
+						 bmc150_magn_samp_freq_table[i].
+						 reg_val <<
+						 BMC150_MAGN_SHIFT_ODR);
+			if (ret < 0)
+				return ret;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static s32 bmc150_magn_compensate_x(struct bmc150_magn_trim_regs *tregs, s16 x,
+				    u16 rhall)
+{
+	s16 val;
+	u16 xyz1 = le16_to_cpu(tregs->xyz1);
+
+	if (x == BMC150_MAGN_XY_OVERFLOW_VAL)
+		return S32_MIN;
+
+	if (!rhall)
+		rhall = xyz1;
+
+	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
+	val = ((s16)((((s32)x) * ((((((((s32)tregs->xy2) * ((((s32)val) *
+	      ((s32)val)) >> 7)) + (((s32)val) *
+	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
+	      ((s32)(((s16)tregs->x2) + ((s16)0xA0)))) >> 12)) >> 13)) +
+	      (((s16)tregs->x1) << 3);
+
+	return (s32)val;
+}
+
+static s32 bmc150_magn_compensate_y(struct bmc150_magn_trim_regs *tregs, s16 y,
+				    u16 rhall)
+{
+	s16 val;
+	u16 xyz1 = le16_to_cpu(tregs->xyz1);
+
+	if (y == BMC150_MAGN_XY_OVERFLOW_VAL)
+		return S32_MIN;
+
+	if (!rhall)
+		rhall = xyz1;
+
+	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
+	val = ((s16)((((s32)y) * ((((((((s32)tregs->xy2) * ((((s32)val) *
+	      ((s32)val)) >> 7)) + (((s32)val) *
+	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
+	      ((s32)(((s16)tregs->y2) + ((s16)0xA0)))) >> 12)) >> 13)) +
+	      (((s16)tregs->y1) << 3);
+
+	return (s32)val;
+}
+
+static s32 bmc150_magn_compensate_z(struct bmc150_magn_trim_regs *tregs, s16 z,
+				    u16 rhall)
+{
+	s32 val;
+	u16 xyz1 = le16_to_cpu(tregs->xyz1);
+	u16 z1 = le16_to_cpu(tregs->z1);
+	s16 z2 = le16_to_cpu(tregs->z2);
+	s16 z3 = le16_to_cpu(tregs->z3);
+	s16 z4 = le16_to_cpu(tregs->z4);
+
+	if (z == BMC150_MAGN_Z_OVERFLOW_VAL)
+		return S32_MIN;
+
+	val = (((((s32)(z - z4)) << 15) - ((((s32)z3) * ((s32)(((s16)rhall) -
+	      ((s16)xyz1)))) >> 2)) / (z2 + ((s16)(((((s32)z1) *
+	      ((((s16)rhall) << 1))) + (1 << 15)) >> 16))));
+
+	return val;
+}
+
+static int bmc150_magn_read_xyz(struct bmc150_magn_data *data, s32 *buffer)
+{
+	int ret;
+	__le16 values[AXIS_XYZR_MAX];
+	s16 raw_x, raw_y, raw_z;
+	u16 rhall;
+	struct bmc150_magn_trim_regs tregs;
+
+	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_X_L,
+			       values, sizeof(values));
+	if (ret < 0)
+		return ret;
+
+	raw_x = (s16)le16_to_cpu(values[AXIS_X]) >> BMC150_MAGN_SHIFT_XY_L;
+	raw_y = (s16)le16_to_cpu(values[AXIS_Y]) >> BMC150_MAGN_SHIFT_XY_L;
+	raw_z = (s16)le16_to_cpu(values[AXIS_Z]) >> BMC150_MAGN_SHIFT_Z_L;
+	rhall = le16_to_cpu(values[RHALL]) >> BMC150_MAGN_SHIFT_RHALL_L;
+
+	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
+			       &tregs, sizeof(tregs));
+	if (ret < 0)
+		return ret;
+
+	buffer[AXIS_X] = bmc150_magn_compensate_x(&tregs, raw_x, rhall);
+	buffer[AXIS_Y] = bmc150_magn_compensate_y(&tregs, raw_y, rhall);
+	buffer[AXIS_Z] = bmc150_magn_compensate_z(&tregs, raw_z, rhall);
+
+	return 0;
+}
+
+static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret, tmp;
+	s32 values[AXIS_XYZ_MAX];
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev))
+			return -EBUSY;
+		mutex_lock(&data->mutex);
+
+		ret = bmc150_magn_set_power_state(data, true);
+		if (ret < 0)
+			return ret;
+
+		ret = bmc150_magn_read_xyz(data, values);
+		if (ret < 0) {
+			bmc150_magn_set_power_state(data, false);
+			mutex_unlock(&data->mutex);
+			return ret;
+		}
+		*val = values[chan->scan_index];
+
+		ret = bmc150_magn_set_power_state(data, false);
+		if (ret < 0)
+			return ret;
+
+		mutex_unlock(&data->mutex);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * The API/driver performs an off-chip temperature
+		 * compensation and outputs x/y/z magnetic field data in
+		 * 16 LSB/uT to the upper application layer.
+		 */
+		*val = 0;
+		*val2 = 625;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = bmc150_magn_get_odr(data, val);
+		if (ret < 0)
+			return ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CALIBREPETITIONS:
+		switch (chan->channel2) {
+		case IIO_MOD_X:
+		case IIO_MOD_Y:
+			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
+					  &tmp);
+			if (ret < 0)
+				return ret;
+			*val = BMC150_MAGN_REGVAL_TO_REPXY(tmp);
+			return IIO_VAL_INT;
+		case IIO_MOD_Z:
+			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
+					  &tmp);
+			if (ret < 0)
+				return ret;
+			*val = BMC150_MAGN_REGVAL_TO_REPZ(tmp);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int bmc150_magn_write_raw(struct iio_dev *indio_dev,
+				 struct iio_chan_spec const *chan,
+				 int val, int val2, long mask)
+{
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		mutex_lock(&data->mutex);
+		ret = bmc150_magn_set_odr(data, val);
+		mutex_unlock(&data->mutex);
+		return ret;
+	case IIO_CHAN_INFO_CALIBREPETITIONS:
+		switch (chan->channel2) {
+		case IIO_MOD_X:
+		case IIO_MOD_Y:
+			if (val < 1 || val > 511)
+				return -EINVAL;
+			return regmap_update_bits(data->regmap,
+						  BMC150_MAGN_REG_REP_XY,
+						  0xFF,
+						  BMC150_MAGN_REPXY_TO_REGVAL
+						  (val));
+		case IIO_MOD_Z:
+			if (val < 1 || val > 256)
+				return -EINVAL;
+			return regmap_update_bits(data->regmap,
+						  BMC150_MAGN_REG_REP_Z,
+						  0xFF,
+						  BMC150_MAGN_REPZ_TO_REGVAL
+						  (val));
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int bmc150_magn_validate_trigger(struct iio_dev *indio_dev,
+					struct iio_trigger *trig)
+{
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+
+	if (data->dready_trig != trig)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int bmc150_magn_update_scan_mode(struct iio_dev *indio_dev,
+					const unsigned long *scan_mask)
+{
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+
+	mutex_lock(&data->mutex);
+	kfree(data->buffer);
+	data->buffer = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
+	mutex_unlock(&data->mutex);
+
+	if (!data->buffer)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("2 6 8 10 15 20 25 30");
+
+static struct attribute *bmc150_magn_attributes[] = {
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group bmc150_magn_attrs_group = {
+	.attrs = bmc150_magn_attributes,
+};
+
+#define BMC150_MAGN_CHANNEL(_axis) {					\
+	.type = IIO_MAGN,						\
+	.modified = 1,							\
+	.channel2 = IIO_MOD_##_axis,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
+			      BIT(IIO_CHAN_INFO_CALIBREPETITIONS),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) |	\
+				    BIT(IIO_CHAN_INFO_SCALE),		\
+	.scan_index = AXIS_##_axis,					\
+	.scan_type = {							\
+		.sign = 's',						\
+		.realbits = 32,						\
+		.storagebits = 32,					\
+		.shift = 0,						\
+		.endianness = IIO_LE					\
+	},								\
+}
+
+static const struct iio_chan_spec bmc150_magn_channels[] = {
+	BMC150_MAGN_CHANNEL(X),
+	BMC150_MAGN_CHANNEL(Y),
+	BMC150_MAGN_CHANNEL(Z),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+static const struct iio_info bmc150_magn_info = {
+	.attrs = &bmc150_magn_attrs_group,
+	.read_raw = bmc150_magn_read_raw,
+	.write_raw = bmc150_magn_write_raw,
+	.validate_trigger = bmc150_magn_validate_trigger,
+	.update_scan_mode = bmc150_magn_update_scan_mode,
+	.driver_module = THIS_MODULE,
+};
+
+static const unsigned long bmc150_magn_scan_masks[] = {0x07, 0};
+
+static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+	ret = bmc150_magn_read_xyz(data, data->buffer);
+	mutex_unlock(&data->mutex);
+	if (ret < 0)
+		goto err;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+					   pf->timestamp);
+
+err:
+	iio_trigger_notify_done(data->dready_trig);
+
+	return IRQ_HANDLED;
+}
+
+static int bmc150_magn_init(struct bmc150_magn_data *data)
+{
+	int ret, chip_id;
+	struct bmc150_magn_preset preset;
+	struct bmc150_magn_trim_regs tregs;
+
+	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND,
+					 false);
+	if (ret < 0) {
+		dev_err(&data->client->dev,
+			"Failed to bring up device from suspend mode\n");
+		return ret;
+	}
+
+	ret = regmap_read(data->regmap, BMC150_MAGN_REG_CHIP_ID, &chip_id);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Failed reading chip id\n");
+		goto err_poweroff;
+	}
+	if (chip_id != BMC150_MAGN_CHIP_ID_VAL) {
+		dev_err(&data->client->dev, "Invalid chip id 0x%x\n", ret);
+		ret = -ENODEV;
+		goto err_poweroff;
+	}
+	dev_dbg(&data->client->dev, "Chip id %x\n", ret);
+
+	preset = bmc150_magn_presets_table[BMC150_MAGN_DEFAULT_PRESET];
+	ret = bmc150_magn_set_odr(data, preset.odr);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Failed to set ODR to %d\n",
+			preset.odr);
+		goto err_poweroff;
+	}
+
+	ret = regmap_update_bits(data->regmap,
+				 BMC150_MAGN_REG_REP_XY,
+				 0xFF,
+				 BMC150_MAGN_REPXY_TO_REGVAL(preset.rep_xy));
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Failed to set REP XY to %d\n",
+			preset.rep_xy);
+		goto err_poweroff;
+	}
+
+	ret = regmap_update_bits(data->regmap,
+				 BMC150_MAGN_REG_REP_Z,
+				 0xFF,
+				 BMC150_MAGN_REPZ_TO_REGVAL(preset.rep_z));
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Failed to set REP Z to %d\n",
+			preset.rep_z);
+		goto err_poweroff;
+	}
+
+	/* Cache trim registers in regmap. */
+	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
+			       &tregs, sizeof(tregs));
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Failed to read trim registers\n");
+		goto err_poweroff;
+	}
+
+	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
+					 true);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "Failed to power on device\n");
+		goto err_poweroff;
+	}
+
+	return 0;
+
+err_poweroff:
+	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
+	return ret;
+}
+
+static int bmc150_magn_reset_intr(struct bmc150_magn_data *data)
+{
+	int tmp;
+
+	/*
+	 * Data Ready (DRDY) is always cleared after
+	 * readout of data registers ends.
+	 */
+	return regmap_read(data->regmap, BMC150_MAGN_REG_X_L, &tmp);
+}
+
+static int bmc150_magn_trig_try_reen(struct iio_trigger *trig)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (!data->dready_trigger_on)
+		return 0;
+
+	mutex_lock(&data->mutex);
+	ret = bmc150_magn_reset_intr(data);
+	mutex_unlock(&data->mutex);
+
+	return ret;
+}
+
+static int bmc150_magn_data_rdy_trigger_set_state(struct iio_trigger *trig,
+						  bool state)
+{
+	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret = 0;
+
+	mutex_lock(&data->mutex);
+	if (state == data->dready_trigger_on)
+		goto err_unlock;
+
+	ret = bmc150_magn_set_power_state(data, state);
+	if (ret < 0)
+		goto err_unlock;
+
+	ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_INT_DRDY,
+				 BMC150_MAGN_MASK_DRDY_EN,
+				 state << BMC150_MAGN_SHIFT_DRDY_EN);
+	if (ret < 0)
+		goto err_poweroff;
+
+	data->dready_trigger_on = state;
+
+	if (state) {
+		ret = bmc150_magn_reset_intr(data);
+		if (ret < 0)
+			goto err_poweroff;
+	}
+	mutex_unlock(&data->mutex);
+
+	return 0;
+
+err_poweroff:
+	bmc150_magn_set_power_state(data, false);
+err_unlock:
+	mutex_unlock(&data->mutex);
+	return ret;
+}
+
+static const struct iio_trigger_ops bmc150_magn_trigger_ops = {
+	.set_trigger_state = bmc150_magn_data_rdy_trigger_set_state,
+	.try_reenable = bmc150_magn_trig_try_reen,
+	.owner = THIS_MODULE,
+};
+
+static int bmc150_magn_gpio_probe(struct i2c_client *client)
+{
+	struct device *dev;
+	struct gpio_desc *gpio;
+	int ret;
+
+	if (!client)
+		return -EINVAL;
+
+	dev = &client->dev;
+
+	/* data ready GPIO interrupt pin */
+	gpio = devm_gpiod_get_index(dev, BMC150_MAGN_GPIO_INT, 0);
+	if (IS_ERR(gpio)) {
+		dev_err(dev, "ACPI GPIO get index failed\n");
+		return PTR_ERR(gpio);
+	}
+
+	ret = gpiod_direction_input(gpio);
+	if (ret)
+		return ret;
+
+	ret = gpiod_to_irq(gpio);
+
+	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
+
+	return ret;
+}
+
+static const char *bmc150_magn_match_acpi_device(struct device *dev)
+{
+	const struct acpi_device_id *id;
+
+	id = acpi_match_device(dev->driver->acpi_match_table, dev);
+	if (!id)
+		return NULL;
+
+	return dev_name(dev);
+}
+
+static int bmc150_magn_probe(struct i2c_client *client,
+			     const struct i2c_device_id *id)
+{
+	struct bmc150_magn_data *data;
+	struct iio_dev *indio_dev;
+	const char *name = NULL;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	if (id)
+		name = id->name;
+	else if (ACPI_HANDLE(&client->dev))
+		name = bmc150_magn_match_acpi_device(&client->dev);
+	else
+		return -ENOSYS;
+
+	mutex_init(&data->mutex);
+	data->regmap = devm_regmap_init_i2c(client, &bmc150_magn_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "Failed to allocate register map\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	ret = bmc150_magn_init(data);
+	if (ret < 0)
+		return ret;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->channels = bmc150_magn_channels;
+	indio_dev->num_channels = ARRAY_SIZE(bmc150_magn_channels);
+	indio_dev->available_scan_masks = bmc150_magn_scan_masks;
+	indio_dev->name = name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &bmc150_magn_info;
+
+	if (client->irq <= 0)
+		client->irq = bmc150_magn_gpio_probe(client);
+
+	if (client->irq > 0) {
+		data->dready_trig = devm_iio_trigger_alloc(&client->dev,
+							   "%s-dev%d",
+							   indio_dev->name,
+							   indio_dev->id);
+		if (!data->dready_trig) {
+			ret = -ENOMEM;
+			dev_err(&client->dev, "iio trigger alloc failed\n");
+			goto err_poweroff;
+		}
+
+		data->dready_trig->dev.parent = &client->dev;
+		data->dready_trig->ops = &bmc150_magn_trigger_ops;
+		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
+		ret = iio_trigger_register(data->dready_trig);
+		if (ret) {
+			dev_err(&client->dev, "iio trigger register failed\n");
+			goto err_poweroff;
+		}
+
+		ret = iio_triggered_buffer_setup(indio_dev,
+						 &iio_pollfunc_store_time,
+						 bmc150_magn_trigger_handler,
+						 NULL);
+		if (ret < 0) {
+			dev_err(&client->dev,
+				"iio triggered buffer setup failed\n");
+			goto err_trigger_unregister;
+		}
+
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+					     iio_trigger_generic_data_rdy_poll,
+					     NULL,
+					     IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+					     BMC150_MAGN_IRQ_NAME,
+					     data->dready_trig);
+		if (ret < 0) {
+			dev_err(&client->dev, "request irq %d failed\n",
+				client->irq);
+			goto err_buffer_cleanup;
+		}
+	}
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "unable to register iio device\n");
+		goto err_buffer_cleanup;
+	}
+
+	ret = pm_runtime_set_active(&client->dev);
+	if (ret)
+		goto err_iio_unregister;
+
+	pm_runtime_enable(&client->dev);
+	pm_runtime_set_autosuspend_delay(&client->dev,
+					 BMC150_MAGN_AUTO_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(&client->dev);
+
+	dev_dbg(&indio_dev->dev, "Registered device %s\n", name);
+
+	return 0;
+
+err_iio_unregister:
+	iio_device_unregister(indio_dev);
+err_buffer_cleanup:
+	if (data->dready_trig)
+		iio_triggered_buffer_cleanup(indio_dev);
+err_trigger_unregister:
+	if (data->dready_trig)
+		iio_trigger_unregister(data->dready_trig);
+err_poweroff:
+	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
+	return ret;
+}
+
+static int bmc150_magn_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+	pm_runtime_put_noidle(&client->dev);
+
+	iio_device_unregister(indio_dev);
+
+	if (data->dready_trig) {
+		iio_triggered_buffer_cleanup(indio_dev);
+		iio_trigger_unregister(data->dready_trig);
+	}
+	kfree(data->buffer);
+
+	mutex_lock(&data->mutex);
+	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
+	mutex_unlock(&data->mutex);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int bmc150_magn_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
+					 true);
+	mutex_unlock(&data->mutex);
+	if (ret < 0) {
+		dev_err(&data->client->dev, "powering off device failed\n");
+		return -EAGAIN;
+	}
+
+	return 0;
+}
+
+static int bmc150_magn_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+
+	return bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
+					  true);
+}
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+static int bmc150_magn_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
+					 true);
+	mutex_unlock(&data->mutex);
+
+	return ret;
+}
+
+static int bmc150_magn_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct bmc150_magn_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->mutex);
+	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
+					 true);
+	mutex_unlock(&data->mutex);
+
+	return ret;
+}
+#endif
+
+static const struct dev_pm_ops bmc150_magn_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(bmc150_magn_suspend, bmc150_magn_resume)
+	SET_RUNTIME_PM_OPS(bmc150_magn_runtime_suspend,
+			   bmc150_magn_runtime_resume, NULL)
+};
+
+static const struct acpi_device_id bmc150_magn_acpi_match[] = {
+	{"BMC150B", 0},
+	{},
+};
+
+MODULE_DEVICE_TABLE(acpi, bmc150_magn_acpi_match);
+
+static const struct i2c_device_id bmc150_magn_id[] = {
+	{"bmc150_magn", 0},
+	{},
+};
+
+MODULE_DEVICE_TABLE(i2c, bmc150_magn_id);
+
+static struct i2c_driver bmc150_magn_driver = {
+	.driver = {
+		   .name = BMC150_MAGN_DRV_NAME,
+		   .acpi_match_table = ACPI_PTR(bmc150_magn_acpi_match),
+		   .pm = &bmc150_magn_pm_ops,
+		   },
+	.probe = bmc150_magn_probe,
+	.remove = bmc150_magn_remove,
+	.id_table = bmc150_magn_id,
+};
+
+module_i2c_driver(bmc150_magn_driver);
+
+MODULE_AUTHOR("Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("BMC150 magnetometer driver");
-- 
1.9.1

Re: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer

[Jonathan Cameron]

On 17/04/15 11:50, Irina Tirdea wrote:
> Add support for the Bosh BMC150 Magnetometer.
> The specification can be downloaded from:
> http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
> The chip contains both an accelerometer and a magnetometer.
> This patch adds support only for the magnetometer part.
> 
> The temperature compensation formulas are based on bmm050_api.c
> authored by contact-oifgY8usX4GOK76mbL0HZ+jAqQFK86Wj@public.gmane.org
> 
> Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Generally looks good, but a few odd bits and pieces...
Quite a few places you use regmap_update_bits to write with a mask of 0xFF
which seems odd..

Various other bits inline. 
> ---
>  drivers/iio/magnetometer/Kconfig       |   14 +
>  drivers/iio/magnetometer/Makefile      |    2 +
>  drivers/iio/magnetometer/bmc150_magn.c | 1060 ++++++++++++++++++++++++++++++++
>  3 files changed, 1076 insertions(+)
>  create mode 100644 drivers/iio/magnetometer/bmc150_magn.c
> 
> diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
> index a5d6de7..008baca 100644
> --- a/drivers/iio/magnetometer/Kconfig
> +++ b/drivers/iio/magnetometer/Kconfig
> @@ -76,4 +76,18 @@ config IIO_ST_MAGN_SPI_3AXIS
>  	depends on IIO_ST_MAGN_3AXIS
>  	depends on IIO_ST_SENSORS_SPI
>  
> +config BMC150_MAGN
> +	tristate "Bosch BMC150 Magnetometer Driver"
> +	depends on I2C
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say yes here to build support for the BMC150 magnetometer.
> +
> +	  Currently this only supports the device via an i2c interface.
> +
> +	  This is a combo module with both accelerometer and magnetometer.
> +	  This driver is only implementing magnetometer part, which has
> +	  its own address and register map.
> +
>  endmenu
> diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
> index 0f5d3c9..e2c3459 100644
> --- a/drivers/iio/magnetometer/Makefile
> +++ b/drivers/iio/magnetometer/Makefile
> @@ -13,3 +13,5 @@ st_magn-$(CONFIG_IIO_BUFFER) += st_magn_buffer.o
>  
>  obj-$(CONFIG_IIO_ST_MAGN_I2C_3AXIS) += st_magn_i2c.o
>  obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
> +
> +obj-$(CONFIG_BMC150_MAGN) += bmc150_magn.o
> diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
> new file mode 100644
> index 0000000..e970a0c
> --- /dev/null
> +++ b/drivers/iio/magnetometer/bmc150_magn.c
> @@ -0,0 +1,1060 @@
> +/*
> + * Bosch BMC150 three-axis magnetic field sensor driver
> + *
> + * Copyright (c) 2015, Intel Corporation.
> + *
> + * This code is based on bmm050_api.c authored by contact-oifgY8usX4GOK76mbL0HZ0EOCMrvLtNR@public.gmane.org:
> + *
> + * (C) Copyright 2011~2014 Bosch Sensortec GmbH All Rights Reserved
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/slab.h>
> +#include <linux/acpi.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/pm.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/events.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/regmap.h>
> +
> +#define BMC150_MAGN_DRV_NAME			"bmc150_magn"
> +#define BMC150_MAGN_IRQ_NAME			"bmc150_magn_event"
> +#define BMC150_MAGN_GPIO_INT			"interrupt"
> +
> +#define BMC150_MAGN_REG_CHIP_ID			0x40
> +#define BMC150_MAGN_CHIP_ID_VAL			0x32
> +
> +#define BMC150_MAGN_REG_X_L			0x42
> +#define BMC150_MAGN_REG_X_M			0x43
> +#define BMC150_MAGN_REG_Y_L			0x44
> +#define BMC150_MAGN_REG_Y_M			0x45
> +#define BMC150_MAGN_SHIFT_XY_L			3
> +#define BMC150_MAGN_REG_Z_L			0x46
> +#define BMC150_MAGN_REG_Z_M			0x47
> +#define BMC150_MAGN_SHIFT_Z_L			1
> +#define BMC150_MAGN_REG_RHALL_L			0x48
> +#define BMC150_MAGN_REG_RHALL_M			0x49
> +#define BMC150_MAGN_SHIFT_RHALL_L		2
> +
> +#define BMC150_MAGN_REG_INT_STATUS		0x4A
> +
> +#define BMC150_MAGN_REG_POWER			0x4B
> +#define BMC150_MAGN_MASK_POWER_CTL		BIT(0)
> +
> +#define BMC150_MAGN_REG_OPMODE_ODR		0x4C
> +#define BMC150_MAGN_MASK_OPMODE			GENMASK(2, 1)
> +#define BMC150_MAGN_SHIFT_OPMODE		1
> +#define BMC150_MAGN_MODE_NORMAL			0x00
> +#define BMC150_MAGN_MODE_FORCED			0x01
> +#define BMC150_MAGN_MODE_SLEEP			0x03
> +#define BMC150_MAGN_MASK_ODR			GENMASK(5, 3)
> +#define BMC150_MAGN_SHIFT_ODR			3
> +
> +#define BMC150_MAGN_REG_INT			0x4D
> +
> +#define BMC150_MAGN_REG_INT_DRDY		0x4E
> +#define BMC150_MAGN_MASK_DRDY_EN		BIT(7)
> +#define BMC150_MAGN_SHIFT_DRDY_EN		7
> +#define BMC150_MAGN_MASK_DRDY_INT3		BIT(6)
> +#define BMC150_MAGN_MASK_DRDY_Z_EN		BIT(5)
> +#define BMC150_MAGN_MASK_DRDY_Y_EN		BIT(4)
> +#define BMC150_MAGN_MASK_DRDY_X_EN		BIT(3)
> +#define BMC150_MAGN_MASK_DRDY_DR_POLARITY	BIT(2)
> +#define BMC150_MAGN_MASK_DRDY_LATCHING		BIT(1)
> +#define BMC150_MAGN_MASK_DRDY_INT3_POLARITY	BIT(0)
> +
> +#define BMC150_MAGN_REG_LOW_THRESH		0x4F
> +#define BMC150_MAGN_REG_HIGH_THRESH		0x50
> +#define BMC150_MAGN_REG_REP_XY			0x51
> +#define BMC150_MAGN_REG_REP_Z			0x52
> +
> +#define BMC150_MAGN_REG_TRIM_START		0x5D
> +#define BMC150_MAGN_REG_TRIM_END		0x71
> +
> +#define BMC150_MAGN_XY_OVERFLOW_VAL		-4096
> +#define BMC150_MAGN_Z_OVERFLOW_VAL		-16384
> +
> +/* Time from SUSPEND to SLEEP */
> +#define BMC150_MAGN_START_UP_TIME_MS		3
> +
> +#define BMC150_MAGN_AUTO_SUSPEND_DELAY_MS	2000
> +
> +#define BMC150_MAGN_REGVAL_TO_REPXY(regval) (((regval) * 2) + 1)
> +#define BMC150_MAGN_REGVAL_TO_REPZ(regval) ((regval) + 1)
> +#define BMC150_MAGN_REPXY_TO_REGVAL(rep) (((rep) - 1) / 2)
> +#define BMC150_MAGN_REPZ_TO_REGVAL(rep) ((rep) - 1)
> +
> +enum bmc150_magn_axis {
> +	AXIS_X,
> +	AXIS_Y,
> +	AXIS_Z,
> +	RHALL,
> +	AXIS_XYZ_MAX = RHALL,
> +	AXIS_XYZR_MAX,
> +};
> +
> +enum bmc150_magn_power_modes {
> +	BMC150_MAGN_POWER_MODE_SUSPEND,
> +	BMC150_MAGN_POWER_MODE_SLEEP,
> +	BMC150_MAGN_POWER_MODE_NORMAL,
> +};
> +
> +struct bmc150_magn_trim_regs {
> +	s8 x1;
> +	s8 y1;
> +	__le16 reserved1;
> +	u8 reserved2;
> +	__le16 z4;
> +	s8 x2;
> +	s8 y2;
> +	__le16 reserved3;
> +	__le16 z2;
> +	__le16 z1;
> +	__le16 xyz1;
> +	__le16 z3;
> +	s8 xy2;
> +	u8 xy1;
> +} __packed;
> +
> +struct bmc150_magn_data {
> +	struct i2c_client *client;
> +	/*
> +	 * 1. Protect this structure.
> +	 * 2. Serialize sequences that power on/off the device and access HW.
> +	 */
> +	struct mutex mutex;
> +	struct regmap *regmap;
> +	s32 *buffer;
> +	struct iio_trigger *dready_trig;
> +	bool dready_trigger_on;
> +};
> +
> +static const struct {
> +	int freq;
> +	u8 reg_val;
> +} bmc150_magn_samp_freq_table[] = { {10, 0x00},
> +				    {2, 0x01},
> +				    {6, 0x02},
> +				    {8, 0x03},
> +				    {15, 0x04},
> +				    {20, 0x05},
> +				    {25, 0x06},
> +				    {30, 0x07} };
> +
> +enum bmc150_magn_presets {
> +	LOW_POWER_PRESET,
> +	REGULAR_PRESET,
> +	ENHANCED_REGULAR_PRESET,
> +	HIGH_ACCURACY_PRESET
> +};
> +
> +static const struct bmc150_magn_preset {
> +	u8 rep_xy;
> +	u8 rep_z;
> +	u8 odr;
> +} bmc150_magn_presets_table[] = {
> +	[LOW_POWER_PRESET] = {3, 3, 10},
> +	[REGULAR_PRESET] =  {9, 15, 10},
> +	[ENHANCED_REGULAR_PRESET] =  {15, 27, 10},
> +	[HIGH_ACCURACY_PRESET] =  {47, 83, 20},
> +};
> +
> +#define BMC150_MAGN_DEFAULT_PRESET REGULAR_PRESET
> +
> +static bool bmc150_magn_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case BMC150_MAGN_REG_POWER:
> +	case BMC150_MAGN_REG_OPMODE_ODR:
> +	case BMC150_MAGN_REG_INT:
> +	case BMC150_MAGN_REG_INT_DRDY:
> +	case BMC150_MAGN_REG_LOW_THRESH:
> +	case BMC150_MAGN_REG_HIGH_THRESH:
> +	case BMC150_MAGN_REG_REP_XY:
> +	case BMC150_MAGN_REG_REP_Z:
> +		return true;
> +	default:
> +		return false;
> +	};
> +}
> +
> +static bool bmc150_magn_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case BMC150_MAGN_REG_X_L:
> +	case BMC150_MAGN_REG_X_M:
> +	case BMC150_MAGN_REG_Y_L:
> +	case BMC150_MAGN_REG_Y_M:
> +	case BMC150_MAGN_REG_Z_L:
> +	case BMC150_MAGN_REG_Z_M:
> +	case BMC150_MAGN_REG_RHALL_L:
> +	case BMC150_MAGN_REG_RHALL_M:
> +	case BMC150_MAGN_REG_INT_STATUS:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_config bmc150_magn_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +
> +	.max_register = BMC150_MAGN_REG_TRIM_END,
> +	.cache_type = REGCACHE_RBTREE,
> +
> +	.writeable_reg = bmc150_magn_is_writeable_reg,
> +	.volatile_reg = bmc150_magn_is_volatile_reg,
> +};
> +
Why bother with this? It's only called in one place and then with a constant so you'll
always get the top option.
> +static void bmc150_magn_sleep(int sleep_time_ms)
> +{
> +	if (sleep_time_ms < 20)
> +		usleep_range(sleep_time_ms * 1000, 20000);
> +	else
> +		msleep_interruptible(sleep_time_ms);
> +}
> +
> +static int bmc150_magn_set_power_mode(struct bmc150_magn_data *data,
> +				      enum bmc150_magn_power_modes mode,
> +				      bool state)
> +{
> +	int ret;
> +
> +	switch (mode) {
> +	case BMC150_MAGN_POWER_MODE_SUSPEND:
> +		ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_POWER,
> +					 BMC150_MAGN_MASK_POWER_CTL, !state);
> +		if (ret < 0)
> +			return ret;
> +		bmc150_magn_sleep(BMC150_MAGN_START_UP_TIME_MS);
> +		return 0;
> +	case BMC150_MAGN_POWER_MODE_SLEEP:
> +		return regmap_update_bits(data->regmap,
> +					  BMC150_MAGN_REG_OPMODE_ODR,
> +					  BMC150_MAGN_MASK_OPMODE,
> +					  BMC150_MAGN_MODE_SLEEP <<
> +					  BMC150_MAGN_SHIFT_OPMODE);
> +	case BMC150_MAGN_POWER_MODE_NORMAL:
> +		return regmap_update_bits(data->regmap,
> +					  BMC150_MAGN_REG_OPMODE_ODR,
> +					  BMC150_MAGN_MASK_OPMODE,
> +					  BMC150_MAGN_MODE_NORMAL <<
> +					  BMC150_MAGN_SHIFT_OPMODE);
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int bmc150_magn_set_power_state(struct bmc150_magn_data *data, bool on)
> +{
> +#ifdef CONFIG_PM
> +	int ret;
> +
> +	if (on) {
> +		ret = pm_runtime_get_sync(&data->client->dev);
> +	} else {
> +		pm_runtime_mark_last_busy(&data->client->dev);
> +		ret = pm_runtime_put_autosuspend(&data->client->dev);
> +	}
> +
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"failed to change power state to %d\n", on);
> +		if (on)
> +			pm_runtime_put_noidle(&data->client->dev);
> +
> +		return ret;
> +	}
> +#endif
> +
> +	return 0;
> +}
> +
> +static int bmc150_magn_get_odr(struct bmc150_magn_data *data, int *val)
> +{
> +	int ret, reg_val;
> +	u8 i, odr_val;
> +
> +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_OPMODE_ODR, &reg_val);
> +	if (ret < 0)
> +		return ret;
> +	odr_val = (reg_val & BMC150_MAGN_MASK_ODR) >> BMC150_MAGN_SHIFT_ODR;
> +
> +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++)
> +		if (bmc150_magn_samp_freq_table[i].reg_val == odr_val) {
> +			*val = bmc150_magn_samp_freq_table[i].freq;
> +			return 0;
> +		}
> +
> +	return -EINVAL;
> +}
> +
> +static int bmc150_magn_set_odr(struct bmc150_magn_data *data, int val)
> +{
> +	int ret;
> +	u8 i;
> +
> +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++) {
> +		if (bmc150_magn_samp_freq_table[i].freq == val) {
> +			ret = regmap_update_bits(data->regmap,
> +						 BMC150_MAGN_REG_OPMODE_ODR,
> +						 BMC150_MAGN_MASK_ODR,
> +						 bmc150_magn_samp_freq_table[i].
> +						 reg_val <<
> +						 BMC150_MAGN_SHIFT_ODR);
> +			if (ret < 0)
> +				return ret;
> +			return 0;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static s32 bmc150_magn_compensate_x(struct bmc150_magn_trim_regs *tregs, s16 x,
> +				    u16 rhall)
> +{
> +	s16 val;
> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
> +
> +	if (x == BMC150_MAGN_XY_OVERFLOW_VAL)
> +		return S32_MIN;
> +
> +	if (!rhall)
> +		rhall = xyz1;
> +
> +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
> +	val = ((s16)((((s32)x) * ((((((((s32)tregs->xy2) * ((((s32)val) *
> +	      ((s32)val)) >> 7)) + (((s32)val) *
> +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
> +	      ((s32)(((s16)tregs->x2) + ((s16)0xA0)))) >> 12)) >> 13)) +
> +	      (((s16)tregs->x1) << 3);
> +
> +	return (s32)val;
> +}
> +
> +static s32 bmc150_magn_compensate_y(struct bmc150_magn_trim_regs *tregs, s16 y,
> +				    u16 rhall)
> +{
> +	s16 val;
> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
> +
> +	if (y == BMC150_MAGN_XY_OVERFLOW_VAL)
> +		return S32_MIN;
> +
> +	if (!rhall)
> +		rhall = xyz1;
> +
> +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
> +	val = ((s16)((((s32)y) * ((((((((s32)tregs->xy2) * ((((s32)val) *
> +	      ((s32)val)) >> 7)) + (((s32)val) *
> +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
> +	      ((s32)(((s16)tregs->y2) + ((s16)0xA0)))) >> 12)) >> 13)) +
> +	      (((s16)tregs->y1) << 3);
> +
> +	return (s32)val;
> +}
> +
> +static s32 bmc150_magn_compensate_z(struct bmc150_magn_trim_regs *tregs, s16 z,
> +				    u16 rhall)
> +{
> +	s32 val;
> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
> +	u16 z1 = le16_to_cpu(tregs->z1);
> +	s16 z2 = le16_to_cpu(tregs->z2);
> +	s16 z3 = le16_to_cpu(tregs->z3);
> +	s16 z4 = le16_to_cpu(tregs->z4);
> +
> +	if (z == BMC150_MAGN_Z_OVERFLOW_VAL)
> +		return S32_MIN;
> +
> +	val = (((((s32)(z - z4)) << 15) - ((((s32)z3) * ((s32)(((s16)rhall) -
> +	      ((s16)xyz1)))) >> 2)) / (z2 + ((s16)(((((s32)z1) *
> +	      ((((s16)rhall) << 1))) + (1 << 15)) >> 16))));
> +
> +	return val;
> +}
> +
> +static int bmc150_magn_read_xyz(struct bmc150_magn_data *data, s32 *buffer)
> +{
> +	int ret;
> +	__le16 values[AXIS_XYZR_MAX];
> +	s16 raw_x, raw_y, raw_z;
> +	u16 rhall;
> +	struct bmc150_magn_trim_regs tregs;
> +
> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_X_L,
> +			       values, sizeof(values));
> +	if (ret < 0)
> +		return ret;
> +
> +	raw_x = (s16)le16_to_cpu(values[AXIS_X]) >> BMC150_MAGN_SHIFT_XY_L;
> +	raw_y = (s16)le16_to_cpu(values[AXIS_Y]) >> BMC150_MAGN_SHIFT_XY_L;
> +	raw_z = (s16)le16_to_cpu(values[AXIS_Z]) >> BMC150_MAGN_SHIFT_Z_L;
> +	rhall = le16_to_cpu(values[RHALL]) >> BMC150_MAGN_SHIFT_RHALL_L;
> +
> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
> +			       &tregs, sizeof(tregs));
> +	if (ret < 0)
> +		return ret;
> +
> +	buffer[AXIS_X] = bmc150_magn_compensate_x(&tregs, raw_x, rhall);
> +	buffer[AXIS_Y] = bmc150_magn_compensate_y(&tregs, raw_y, rhall);
> +	buffer[AXIS_Z] = bmc150_magn_compensate_z(&tregs, raw_z, rhall);
> +
> +	return 0;
> +}
> +
> +static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int *val, int *val2, long mask)
> +{
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret, tmp;
> +	s32 values[AXIS_XYZ_MAX];
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (iio_buffer_enabled(indio_dev))
> +			return -EBUSY;
> +		mutex_lock(&data->mutex);
> +
> +		ret = bmc150_magn_set_power_state(data, true);
> +		if (ret < 0)
You just returned with the mutex held...  Check the other places this might happen please.
> +			return ret;
> +
> +		ret = bmc150_magn_read_xyz(data, values);
> +		if (ret < 0) {
> +			bmc150_magn_set_power_state(data, false);
> +			mutex_unlock(&data->mutex);
> +			return ret;
> +		}
> +		*val = values[chan->scan_index];
> +
> +		ret = bmc150_magn_set_power_state(data, false);
> +		if (ret < 0)
> +			return ret;
> +
> +		mutex_unlock(&data->mutex);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		/*
> +		 * The API/driver performs an off-chip temperature
> +		 * compensation and outputs x/y/z magnetic field data in
> +		 * 16 LSB/uT to the upper application layer.
> +		 */
> +		*val = 0;
> +		*val2 = 625;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = bmc150_magn_get_odr(data, val);
> +		if (ret < 0)
> +			return ret;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_CALIBREPETITIONS:
> +		switch (chan->channel2) {
> +		case IIO_MOD_X:
> +		case IIO_MOD_Y:
> +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
> +					  &tmp);
> +			if (ret < 0)
> +				return ret;
> +			*val = BMC150_MAGN_REGVAL_TO_REPXY(tmp);
> +			return IIO_VAL_INT;
> +		case IIO_MOD_Z:
> +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
> +					  &tmp);
> +			if (ret < 0)
> +				return ret;
> +			*val = BMC150_MAGN_REGVAL_TO_REPZ(tmp);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int bmc150_magn_write_raw(struct iio_dev *indio_dev,
> +				 struct iio_chan_spec const *chan,
> +				 int val, int val2, long mask)
> +{
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		mutex_lock(&data->mutex);
> +		ret = bmc150_magn_set_odr(data, val);
> +		mutex_unlock(&data->mutex);
> +		return ret;
> +	case IIO_CHAN_INFO_CALIBREPETITIONS:
> +		switch (chan->channel2) {
> +		case IIO_MOD_X:
> +		case IIO_MOD_Y:
> +			if (val < 1 || val > 511)
> +				return -EINVAL;
> +			return regmap_update_bits(data->regmap,
> +						  BMC150_MAGN_REG_REP_XY,
> +						  0xFF,
> +						  BMC150_MAGN_REPXY_TO_REGVAL
> +						  (val));
> +		case IIO_MOD_Z:
> +			if (val < 1 || val > 256)
> +				return -EINVAL;
> +			return regmap_update_bits(data->regmap,
> +						  BMC150_MAGN_REG_REP_Z,
> +						  0xFF,
> +						  BMC150_MAGN_REPZ_TO_REGVAL
> +						  (val));
> +		default:
> +			return -EINVAL;
> +		}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int bmc150_magn_validate_trigger(struct iio_dev *indio_dev,
> +					struct iio_trigger *trig)
> +{
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +
> +	if (data->dready_trig != trig)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int bmc150_magn_update_scan_mode(struct iio_dev *indio_dev,
> +					const unsigned long *scan_mask)
> +{
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +
> +	mutex_lock(&data->mutex);
> +	kfree(data->buffer);
> +	data->buffer = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
Call be cynical, but how large can this buffer get?

I'd just allocate it as part of data in the first place then you
can drop this function entirely and don't have to clean it up
separately.
> +	mutex_unlock(&data->mutex);
> +
> +	if (!data->buffer)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("2 6 8 10 15 20 25 30");
> +
> +static struct attribute *bmc150_magn_attributes[] = {
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group bmc150_magn_attrs_group = {
> +	.attrs = bmc150_magn_attributes,
> +};
> +
> +#define BMC150_MAGN_CHANNEL(_axis) {					\
> +	.type = IIO_MAGN,						\
> +	.modified = 1,							\
> +	.channel2 = IIO_MOD_##_axis,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
> +			      BIT(IIO_CHAN_INFO_CALIBREPETITIONS),	\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) |	\
> +				    BIT(IIO_CHAN_INFO_SCALE),		\
> +	.scan_index = AXIS_##_axis,					\
> +	.scan_type = {							\
> +		.sign = 's',						\
> +		.realbits = 32,						\
> +		.storagebits = 32,					\
> +		.shift = 0,						\
> +		.endianness = IIO_LE					\
> +	},								\
> +}
> +
> +static const struct iio_chan_spec bmc150_magn_channels[] = {
> +	BMC150_MAGN_CHANNEL(X),
> +	BMC150_MAGN_CHANNEL(Y),
> +	BMC150_MAGN_CHANNEL(Z),
> +	IIO_CHAN_SOFT_TIMESTAMP(3),
> +};
> +
> +static const struct iio_info bmc150_magn_info = {
> +	.attrs = &bmc150_magn_attrs_group,
> +	.read_raw = bmc150_magn_read_raw,
> +	.write_raw = bmc150_magn_write_raw,
> +	.validate_trigger = bmc150_magn_validate_trigger,
> +	.update_scan_mode = bmc150_magn_update_scan_mode,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static const unsigned long bmc150_magn_scan_masks[] = {0x07, 0};
> +
> +static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bmc150_magn_read_xyz(data, data->buffer);
> +	mutex_unlock(&data->mutex);
> +	if (ret < 0)
> +		goto err;
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
> +					   pf->timestamp);
> +
> +err:
> +	iio_trigger_notify_done(data->dready_trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int bmc150_magn_init(struct bmc150_magn_data *data)
> +{
> +	int ret, chip_id;
> +	struct bmc150_magn_preset preset;
> +	struct bmc150_magn_trim_regs tregs;
> +
> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND,
> +					 false);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"Failed to bring up device from suspend mode\n");
> +		return ret;
> +	}
> +
> +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_CHIP_ID, &chip_id);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Failed reading chip id\n");
> +		goto err_poweroff;
> +	}
> +	if (chip_id != BMC150_MAGN_CHIP_ID_VAL) {
> +		dev_err(&data->client->dev, "Invalid chip id 0x%x\n", ret);
> +		ret = -ENODEV;
> +		goto err_poweroff;
> +	}
> +	dev_dbg(&data->client->dev, "Chip id %x\n", ret);
> +
> +	preset = bmc150_magn_presets_table[BMC150_MAGN_DEFAULT_PRESET];
> +	ret = bmc150_magn_set_odr(data, preset.odr);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Failed to set ODR to %d\n",
> +			preset.odr);
> +		goto err_poweroff;
> +	}
> +
> +	ret = regmap_update_bits(data->regmap,
> +				 BMC150_MAGN_REG_REP_XY,
> +				 0xFF,
> +				 BMC150_MAGN_REPXY_TO_REGVAL(preset.rep_xy));
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Failed to set REP XY to %d\n",
> +			preset.rep_xy);
> +		goto err_poweroff;
> +	}
> +
> +	ret = regmap_update_bits(data->regmap,
> +				 BMC150_MAGN_REG_REP_Z,
> +				 0xFF,
Umm. With a mask of 0xFF are we not just setting the whole register?  In which
case why use update_bits?   regmap_write instead...
> +				 BMC150_MAGN_REPZ_TO_REGVAL(preset.rep_z));
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Failed to set REP Z to %d\n",
> +			preset.rep_z);
> +		goto err_poweroff;
> +	}
> +
> +	/* Cache trim registers in regmap. */
A little ugly. Is there no way of asking regmap to fill it's cache for certain registers?
Actually as I read it having taken a quick look, regcache_hw_init will read all your registers
given you haven't provided defaults.  Hence this will be cached already..
> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
> +			       &tregs, sizeof(tregs));
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Failed to read trim registers\n");
> +		goto err_poweroff;
> +	}
> +
> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
> +					 true);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "Failed to power on device\n");
> +		goto err_poweroff;
> +	}
> +
> +	return 0;
> +
> +err_poweroff:
> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
> +	return ret;
> +}
> +
> +static int bmc150_magn_reset_intr(struct bmc150_magn_data *data)
> +{
> +	int tmp;
> +
> +	/*
> +	 * Data Ready (DRDY) is always cleared after
> +	 * readout of data registers ends.
> +	 */
> +	return regmap_read(data->regmap, BMC150_MAGN_REG_X_L, &tmp);
Good to see this here.  Often people don't bother on the basis
of course the driver has already read the data register!
(which it might not have done if the trigger is being used by another
device).
> +}
> +
> +static int bmc150_magn_trig_try_reen(struct iio_trigger *trig)
> +{
> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	if (!data->dready_trigger_on)
> +		return 0;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bmc150_magn_reset_intr(data);
> +	mutex_unlock(&data->mutex);
> +
> +	return ret;
> +}
> +
> +static int bmc150_magn_data_rdy_trigger_set_state(struct iio_trigger *trig,
> +						  bool state)
> +{
> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret = 0;
> +
> +	mutex_lock(&data->mutex);
> +	if (state == data->dready_trigger_on)
> +		goto err_unlock;
> +
> +	ret = bmc150_magn_set_power_state(data, state);
> +	if (ret < 0)
> +		goto err_unlock;
> +
> +	ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_INT_DRDY,
> +				 BMC150_MAGN_MASK_DRDY_EN,
> +				 state << BMC150_MAGN_SHIFT_DRDY_EN);
> +	if (ret < 0)
> +		goto err_poweroff;
> +
> +	data->dready_trigger_on = state;
> +
> +	if (state) {
> +		ret = bmc150_magn_reset_intr(data);
> +		if (ret < 0)
> +			goto err_poweroff;
> +	}
> +	mutex_unlock(&data->mutex);
> +
> +	return 0;
> +
> +err_poweroff:
> +	bmc150_magn_set_power_state(data, false);
> +err_unlock:
> +	mutex_unlock(&data->mutex);
> +	return ret;
> +}
> +
> +static const struct iio_trigger_ops bmc150_magn_trigger_ops = {
> +	.set_trigger_state = bmc150_magn_data_rdy_trigger_set_state,
> +	.try_reenable = bmc150_magn_trig_try_reen,
> +	.owner = THIS_MODULE,
> +};
> +
> +static int bmc150_magn_gpio_probe(struct i2c_client *client)
> +{
> +	struct device *dev;
> +	struct gpio_desc *gpio;
> +	int ret;
> +
> +	if (!client)
> +		return -EINVAL;
> +
> +	dev = &client->dev;
> +
> +	/* data ready GPIO interrupt pin */
> +	gpio = devm_gpiod_get_index(dev, BMC150_MAGN_GPIO_INT, 0);
> +	if (IS_ERR(gpio)) {
> +		dev_err(dev, "ACPI GPIO get index failed\n");
> +		return PTR_ERR(gpio);
> +	}
> +
> +	ret = gpiod_direction_input(gpio);
> +	if (ret)
> +		return ret;
> +
> +	ret = gpiod_to_irq(gpio);
> +
> +	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
> +
> +	return ret;
> +}
> +
> +static const char *bmc150_magn_match_acpi_device(struct device *dev)
> +{
> +	const struct acpi_device_id *id;
> +
> +	id = acpi_match_device(dev->driver->acpi_match_table, dev);
> +	if (!id)
> +		return NULL;
> +
> +	return dev_name(dev);
> +}
> +
> +static int bmc150_magn_probe(struct i2c_client *client,
> +			     const struct i2c_device_id *id)
> +{
> +	struct bmc150_magn_data *data;
> +	struct iio_dev *indio_dev;
> +	const char *name = NULL;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	data->client = client;
> +
> +	if (id)
> +		name = id->name;
> +	else if (ACPI_HANDLE(&client->dev))
> +		name = bmc150_magn_match_acpi_device(&client->dev);
> +	else
> +		return -ENOSYS;
> +
> +	mutex_init(&data->mutex);
> +	data->regmap = devm_regmap_init_i2c(client, &bmc150_magn_regmap_config);
> +	if (IS_ERR(data->regmap)) {
> +		dev_err(&client->dev, "Failed to allocate register map\n");
> +		return PTR_ERR(data->regmap);
> +	}
> +
> +	ret = bmc150_magn_init(data);
> +	if (ret < 0)
> +		return ret;
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->channels = bmc150_magn_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(bmc150_magn_channels);
> +	indio_dev->available_scan_masks = bmc150_magn_scan_masks;
> +	indio_dev->name = name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &bmc150_magn_info;
> +
> +	if (client->irq <= 0)
> +		client->irq = bmc150_magn_gpio_probe(client);
> +
> +	if (client->irq > 0) {
> +		data->dready_trig = devm_iio_trigger_alloc(&client->dev,
> +							   "%s-dev%d",
> +							   indio_dev->name,
> +							   indio_dev->id);
> +		if (!data->dready_trig) {
> +			ret = -ENOMEM;
> +			dev_err(&client->dev, "iio trigger alloc failed\n");
> +			goto err_poweroff;
> +		}
> +
> +		data->dready_trig->dev.parent = &client->dev;
> +		data->dready_trig->ops = &bmc150_magn_trigger_ops;
> +		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
> +		ret = iio_trigger_register(data->dready_trig);
> +		if (ret) {
> +			dev_err(&client->dev, "iio trigger register failed\n");
> +			goto err_poweroff;
> +		}
> +
> +		ret = iio_triggered_buffer_setup(indio_dev,
> +						 &iio_pollfunc_store_time,
> +						 bmc150_magn_trigger_handler,
> +						 NULL);
> +		if (ret < 0) {
> +			dev_err(&client->dev,
> +				"iio triggered buffer setup failed\n");
> +			goto err_trigger_unregister;
> +		}
> +
> +		ret = devm_request_threaded_irq(&client->dev, client->irq,
> +					     iio_trigger_generic_data_rdy_poll,
> +					     NULL,
> +					     IRQF_TRIGGER_RISING | IRQF_ONESHOT,
> +					     BMC150_MAGN_IRQ_NAME,
> +					     data->dready_trig);
> +		if (ret < 0) {
> +			dev_err(&client->dev, "request irq %d failed\n",
> +				client->irq);
> +			goto err_buffer_cleanup;
> +		}
> +	}
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "unable to register iio device\n");
> +		goto err_buffer_cleanup;
> +	}
> +
> +	ret = pm_runtime_set_active(&client->dev);
> +	if (ret)
> +		goto err_iio_unregister;
> +
> +	pm_runtime_enable(&client->dev);
> +	pm_runtime_set_autosuspend_delay(&client->dev,
> +					 BMC150_MAGN_AUTO_SUSPEND_DELAY_MS);
> +	pm_runtime_use_autosuspend(&client->dev);
> +
> +	dev_dbg(&indio_dev->dev, "Registered device %s\n", name);
> +
> +	return 0;
> +
> +err_iio_unregister:
> +	iio_device_unregister(indio_dev);
> +err_buffer_cleanup:

Hmm. There is an issue with this being obviously correct.
The unwind ordering different from setup.
Because you have devm_request_threaded_irq calls they will unwind only after these
calls, but should occur before.
Now it probaby makes no difference, but it does fail the obviously correct test.

It's also the case in the remove.  I'd be inclined not to use the devm versin
of the irq request, but do it explicitly. This one comes up a lot and much like
the devm_iio_register_device call it's only really a good idea if everything
is managed.  In mixed cases, I'd avoid it.

Maybe I'm just being overly fussy...

> +	if (data->dready_trig)
> +		iio_triggered_buffer_cleanup(indio_dev);
> +err_trigger_unregister:
> +	if (data->dready_trig)
> +		iio_trigger_unregister(data->dready_trig);
> +err_poweroff:
> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
> +	return ret;
> +}
> +
> +static int bmc150_magn_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +
> +	pm_runtime_disable(&client->dev);
> +	pm_runtime_set_suspended(&client->dev);
> +	pm_runtime_put_noidle(&client->dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	if (data->dready_trig) {
> +		iio_triggered_buffer_cleanup(indio_dev);
> +		iio_trigger_unregister(data->dready_trig);
> +	}
As mentioned above, this clean up isn't needed if you simply
always make data->buffer the largest size it can ever be.
> +	kfree(data->buffer);
> +
> +	mutex_lock(&data->mutex);
> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
> +	mutex_unlock(&data->mutex);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int bmc150_magn_runtime_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
> +					 true);
> +	mutex_unlock(&data->mutex);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "powering off device failed\n");
> +		return -EAGAIN;
> +	}
> +
> +	return 0;
> +}
> +
> +static int bmc150_magn_runtime_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +
> +	return bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
> +					  true);
> +}
> +#endif
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int bmc150_magn_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
> +					 true);
> +	mutex_unlock(&data->mutex);
> +
> +	return ret;
> +}
> +
> +static int bmc150_magn_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	mutex_lock(&data->mutex);
> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
> +					 true);
> +	mutex_unlock(&data->mutex);
> +
> +	return ret;
> +}
> +#endif
> +
> +static const struct dev_pm_ops bmc150_magn_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(bmc150_magn_suspend, bmc150_magn_resume)
> +	SET_RUNTIME_PM_OPS(bmc150_magn_runtime_suspend,
> +			   bmc150_magn_runtime_resume, NULL)
> +};
> +
> +static const struct acpi_device_id bmc150_magn_acpi_match[] = {
> +	{"BMC150B", 0},
> +	{},
> +};
nitpick, no blank line here. Tends to directly associate the structure
with the following macro which is visually nice..
> +
> +MODULE_DEVICE_TABLE(acpi, bmc150_magn_acpi_match);
> +
> +static const struct i2c_device_id bmc150_magn_id[] = {
> +	{"bmc150_magn", 0},
> +	{},
> +};
Nitpick, no blank line.
> +
> +MODULE_DEVICE_TABLE(i2c, bmc150_magn_id);
> +
> +static struct i2c_driver bmc150_magn_driver = {
> +	.driver = {
> +		   .name = BMC150_MAGN_DRV_NAME,
> +		   .acpi_match_table = ACPI_PTR(bmc150_magn_acpi_match),
> +		   .pm = &bmc150_magn_pm_ops,
> +		   },
> +	.probe = bmc150_magn_probe,
> +	.remove = bmc150_magn_remove,
> +	.id_table = bmc150_magn_id,
> +};
Nitpick. I'd not bother with the blank line here.
> +
> +module_i2c_driver(bmc150_magn_driver);
> +
> +MODULE_AUTHOR("Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("BMC150 magnetometer driver");
> 

RE: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer

[Tirdea, Irina]

> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
> Sent: 18 April, 2015 21:07
> To: Tirdea, Irina; linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Hartmut Knaack; Lars-Peter Clausen; Peter Meerwald; Rob Herring; Pawel Moll; Mark Rutland; Ian
> Campbell; Kumar Gala
> Subject: Re: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer
> 
> On 17/04/15 11:50, Irina Tirdea wrote:
> > Add support for the Bosh BMC150 Magnetometer.
> > The specification can be downloaded from:
> > http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
> > The chip contains both an accelerometer and a magnetometer.
> > This patch adds support only for the magnetometer part.
> >
> > The temperature compensation formulas are based on bmm050_api.c
> > authored by contact-oifgY8usX4GOK76mbL0HZ+jAqQFK86Wj@public.gmane.org
> >
> > Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Generally looks good, but a few odd bits and pieces...

Thanks for the review, Jonathan!

> Quite a few places you use regmap_update_bits to write with a mask of 0xFF
> which seems odd..
> 
The idea there is to not do unnecessary i2c_reads/writes if the value does not change:
regmap_update_bits will check the cached value and only do the i2c transfer if the value 
did not change.
 
> Various other bits inline.
> > ---
> >  drivers/iio/magnetometer/Kconfig       |   14 +
> >  drivers/iio/magnetometer/Makefile      |    2 +
> >  drivers/iio/magnetometer/bmc150_magn.c | 1060 ++++++++++++++++++++++++++++++++
> >  3 files changed, 1076 insertions(+)
> >  create mode 100644 drivers/iio/magnetometer/bmc150_magn.c
> >
> > diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
> > index a5d6de7..008baca 100644
> > --- a/drivers/iio/magnetometer/Kconfig
> > +++ b/drivers/iio/magnetometer/Kconfig
> > @@ -76,4 +76,18 @@ config IIO_ST_MAGN_SPI_3AXIS
> >  	depends on IIO_ST_MAGN_3AXIS
> >  	depends on IIO_ST_SENSORS_SPI
> >
> > +config BMC150_MAGN
> > +	tristate "Bosch BMC150 Magnetometer Driver"
> > +	depends on I2C
> > +	select IIO_BUFFER
> > +	select IIO_TRIGGERED_BUFFER
> > +	help
> > +	  Say yes here to build support for the BMC150 magnetometer.
> > +
> > +	  Currently this only supports the device via an i2c interface.
> > +
> > +	  This is a combo module with both accelerometer and magnetometer.
> > +	  This driver is only implementing magnetometer part, which has
> > +	  its own address and register map.
> > +
> >  endmenu
> > diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
> > index 0f5d3c9..e2c3459 100644
> > --- a/drivers/iio/magnetometer/Makefile
> > +++ b/drivers/iio/magnetometer/Makefile
> > @@ -13,3 +13,5 @@ st_magn-$(CONFIG_IIO_BUFFER) += st_magn_buffer.o
> >
> >  obj-$(CONFIG_IIO_ST_MAGN_I2C_3AXIS) += st_magn_i2c.o
> >  obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
> > +
> > +obj-$(CONFIG_BMC150_MAGN) += bmc150_magn.o
> > diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
> > new file mode 100644
> > index 0000000..e970a0c
> > --- /dev/null
> > +++ b/drivers/iio/magnetometer/bmc150_magn.c
> > @@ -0,0 +1,1060 @@
> > +/*
> > + * Bosch BMC150 three-axis magnetic field sensor driver
> > + *
> > + * Copyright (c) 2015, Intel Corporation.
> > + *
> > + * This code is based on bmm050_api.c authored by contact-oifgY8usX4GOK76mbL0HZ0EOCMrvLtNR@public.gmane.org:
> > + *
> > + * (C) Copyright 2011~2014 Bosch Sensortec GmbH All Rights Reserved
> > + *
> > + * This program is free software; you can redistribute it and/or modify it
> > + * under the terms and conditions of the GNU General Public License,
> > + * version 2, as published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope it will be useful, but WITHOUT
> > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> > + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> > + * more details.
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/i2c.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/delay.h>
> > +#include <linux/slab.h>
> > +#include <linux/acpi.h>
> > +#include <linux/gpio/consumer.h>
> > +#include <linux/pm.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/iio/buffer.h>
> > +#include <linux/iio/events.h>
> > +#include <linux/iio/trigger.h>
> > +#include <linux/iio/trigger_consumer.h>
> > +#include <linux/iio/triggered_buffer.h>
> > +#include <linux/regmap.h>
> > +
> > +#define BMC150_MAGN_DRV_NAME			"bmc150_magn"
> > +#define BMC150_MAGN_IRQ_NAME			"bmc150_magn_event"
> > +#define BMC150_MAGN_GPIO_INT			"interrupt"
> > +
> > +#define BMC150_MAGN_REG_CHIP_ID			0x40
> > +#define BMC150_MAGN_CHIP_ID_VAL			0x32
> > +
> > +#define BMC150_MAGN_REG_X_L			0x42
> > +#define BMC150_MAGN_REG_X_M			0x43
> > +#define BMC150_MAGN_REG_Y_L			0x44
> > +#define BMC150_MAGN_REG_Y_M			0x45
> > +#define BMC150_MAGN_SHIFT_XY_L			3
> > +#define BMC150_MAGN_REG_Z_L			0x46
> > +#define BMC150_MAGN_REG_Z_M			0x47
> > +#define BMC150_MAGN_SHIFT_Z_L			1
> > +#define BMC150_MAGN_REG_RHALL_L			0x48
> > +#define BMC150_MAGN_REG_RHALL_M			0x49
> > +#define BMC150_MAGN_SHIFT_RHALL_L		2
> > +
> > +#define BMC150_MAGN_REG_INT_STATUS		0x4A
> > +
> > +#define BMC150_MAGN_REG_POWER			0x4B
> > +#define BMC150_MAGN_MASK_POWER_CTL		BIT(0)
> > +
> > +#define BMC150_MAGN_REG_OPMODE_ODR		0x4C
> > +#define BMC150_MAGN_MASK_OPMODE			GENMASK(2, 1)
> > +#define BMC150_MAGN_SHIFT_OPMODE		1
> > +#define BMC150_MAGN_MODE_NORMAL			0x00
> > +#define BMC150_MAGN_MODE_FORCED			0x01
> > +#define BMC150_MAGN_MODE_SLEEP			0x03
> > +#define BMC150_MAGN_MASK_ODR			GENMASK(5, 3)
> > +#define BMC150_MAGN_SHIFT_ODR			3
> > +
> > +#define BMC150_MAGN_REG_INT			0x4D
> > +
> > +#define BMC150_MAGN_REG_INT_DRDY		0x4E
> > +#define BMC150_MAGN_MASK_DRDY_EN		BIT(7)
> > +#define BMC150_MAGN_SHIFT_DRDY_EN		7
> > +#define BMC150_MAGN_MASK_DRDY_INT3		BIT(6)
> > +#define BMC150_MAGN_MASK_DRDY_Z_EN		BIT(5)
> > +#define BMC150_MAGN_MASK_DRDY_Y_EN		BIT(4)
> > +#define BMC150_MAGN_MASK_DRDY_X_EN		BIT(3)
> > +#define BMC150_MAGN_MASK_DRDY_DR_POLARITY	BIT(2)
> > +#define BMC150_MAGN_MASK_DRDY_LATCHING		BIT(1)
> > +#define BMC150_MAGN_MASK_DRDY_INT3_POLARITY	BIT(0)
> > +
> > +#define BMC150_MAGN_REG_LOW_THRESH		0x4F
> > +#define BMC150_MAGN_REG_HIGH_THRESH		0x50
> > +#define BMC150_MAGN_REG_REP_XY			0x51
> > +#define BMC150_MAGN_REG_REP_Z			0x52
> > +
> > +#define BMC150_MAGN_REG_TRIM_START		0x5D
> > +#define BMC150_MAGN_REG_TRIM_END		0x71
> > +
> > +#define BMC150_MAGN_XY_OVERFLOW_VAL		-4096
> > +#define BMC150_MAGN_Z_OVERFLOW_VAL		-16384
> > +
> > +/* Time from SUSPEND to SLEEP */
> > +#define BMC150_MAGN_START_UP_TIME_MS		3
> > +
> > +#define BMC150_MAGN_AUTO_SUSPEND_DELAY_MS	2000
> > +
> > +#define BMC150_MAGN_REGVAL_TO_REPXY(regval) (((regval) * 2) + 1)
> > +#define BMC150_MAGN_REGVAL_TO_REPZ(regval) ((regval) + 1)
> > +#define BMC150_MAGN_REPXY_TO_REGVAL(rep) (((rep) - 1) / 2)
> > +#define BMC150_MAGN_REPZ_TO_REGVAL(rep) ((rep) - 1)
> > +
> > +enum bmc150_magn_axis {
> > +	AXIS_X,
> > +	AXIS_Y,
> > +	AXIS_Z,
> > +	RHALL,
> > +	AXIS_XYZ_MAX = RHALL,
> > +	AXIS_XYZR_MAX,
> > +};
> > +
> > +enum bmc150_magn_power_modes {
> > +	BMC150_MAGN_POWER_MODE_SUSPEND,
> > +	BMC150_MAGN_POWER_MODE_SLEEP,
> > +	BMC150_MAGN_POWER_MODE_NORMAL,
> > +};
> > +
> > +struct bmc150_magn_trim_regs {
> > +	s8 x1;
> > +	s8 y1;
> > +	__le16 reserved1;
> > +	u8 reserved2;
> > +	__le16 z4;
> > +	s8 x2;
> > +	s8 y2;
> > +	__le16 reserved3;
> > +	__le16 z2;
> > +	__le16 z1;
> > +	__le16 xyz1;
> > +	__le16 z3;
> > +	s8 xy2;
> > +	u8 xy1;
> > +} __packed;
> > +
> > +struct bmc150_magn_data {
> > +	struct i2c_client *client;
> > +	/*
> > +	 * 1. Protect this structure.
> > +	 * 2. Serialize sequences that power on/off the device and access HW.
> > +	 */
> > +	struct mutex mutex;
> > +	struct regmap *regmap;
> > +	s32 *buffer;
> > +	struct iio_trigger *dready_trig;
> > +	bool dready_trigger_on;
> > +};
> > +
> > +static const struct {
> > +	int freq;
> > +	u8 reg_val;
> > +} bmc150_magn_samp_freq_table[] = { {10, 0x00},
> > +				    {2, 0x01},
> > +				    {6, 0x02},
> > +				    {8, 0x03},
> > +				    {15, 0x04},
> > +				    {20, 0x05},
> > +				    {25, 0x06},
> > +				    {30, 0x07} };
> > +
> > +enum bmc150_magn_presets {
> > +	LOW_POWER_PRESET,
> > +	REGULAR_PRESET,
> > +	ENHANCED_REGULAR_PRESET,
> > +	HIGH_ACCURACY_PRESET
> > +};
> > +
> > +static const struct bmc150_magn_preset {
> > +	u8 rep_xy;
> > +	u8 rep_z;
> > +	u8 odr;
> > +} bmc150_magn_presets_table[] = {
> > +	[LOW_POWER_PRESET] = {3, 3, 10},
> > +	[REGULAR_PRESET] =  {9, 15, 10},
> > +	[ENHANCED_REGULAR_PRESET] =  {15, 27, 10},
> > +	[HIGH_ACCURACY_PRESET] =  {47, 83, 20},
> > +};
> > +
> > +#define BMC150_MAGN_DEFAULT_PRESET REGULAR_PRESET
> > +
> > +static bool bmc150_magn_is_writeable_reg(struct device *dev, unsigned int reg)
> > +{
> > +	switch (reg) {
> > +	case BMC150_MAGN_REG_POWER:
> > +	case BMC150_MAGN_REG_OPMODE_ODR:
> > +	case BMC150_MAGN_REG_INT:
> > +	case BMC150_MAGN_REG_INT_DRDY:
> > +	case BMC150_MAGN_REG_LOW_THRESH:
> > +	case BMC150_MAGN_REG_HIGH_THRESH:
> > +	case BMC150_MAGN_REG_REP_XY:
> > +	case BMC150_MAGN_REG_REP_Z:
> > +		return true;
> > +	default:
> > +		return false;
> > +	};
> > +}
> > +
> > +static bool bmc150_magn_is_volatile_reg(struct device *dev, unsigned int reg)
> > +{
> > +	switch (reg) {
> > +	case BMC150_MAGN_REG_X_L:
> > +	case BMC150_MAGN_REG_X_M:
> > +	case BMC150_MAGN_REG_Y_L:
> > +	case BMC150_MAGN_REG_Y_M:
> > +	case BMC150_MAGN_REG_Z_L:
> > +	case BMC150_MAGN_REG_Z_M:
> > +	case BMC150_MAGN_REG_RHALL_L:
> > +	case BMC150_MAGN_REG_RHALL_M:
> > +	case BMC150_MAGN_REG_INT_STATUS:
> > +		return true;
> > +	default:
> > +		return false;
> > +	}
> > +}
> > +
> > +static const struct regmap_config bmc150_magn_regmap_config = {
> > +	.reg_bits = 8,
> > +	.val_bits = 8,
> > +
> > +	.max_register = BMC150_MAGN_REG_TRIM_END,
> > +	.cache_type = REGCACHE_RBTREE,
> > +
> > +	.writeable_reg = bmc150_magn_is_writeable_reg,
> > +	.volatile_reg = bmc150_magn_is_volatile_reg,
> > +};
> > +
> Why bother with this? It's only called in one place and then with a constant so you'll
> always get the top option.

Indeed. I thought I will have multiple usages, but now it does not make sense anymore.
I will remove it and use usleep_range instead.

> > +static void bmc150_magn_sleep(int sleep_time_ms)
> > +{
> > +	if (sleep_time_ms < 20)
> > +		usleep_range(sleep_time_ms * 1000, 20000);
> > +	else
> > +		msleep_interruptible(sleep_time_ms);
> > +}
> > +
> > +static int bmc150_magn_set_power_mode(struct bmc150_magn_data *data,
> > +				      enum bmc150_magn_power_modes mode,
> > +				      bool state)
> > +{
> > +	int ret;
> > +
> > +	switch (mode) {
> > +	case BMC150_MAGN_POWER_MODE_SUSPEND:
> > +		ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_POWER,
> > +					 BMC150_MAGN_MASK_POWER_CTL, !state);
> > +		if (ret < 0)
> > +			return ret;
> > +		bmc150_magn_sleep(BMC150_MAGN_START_UP_TIME_MS);
> > +		return 0;
> > +	case BMC150_MAGN_POWER_MODE_SLEEP:
> > +		return regmap_update_bits(data->regmap,
> > +					  BMC150_MAGN_REG_OPMODE_ODR,
> > +					  BMC150_MAGN_MASK_OPMODE,
> > +					  BMC150_MAGN_MODE_SLEEP <<
> > +					  BMC150_MAGN_SHIFT_OPMODE);
> > +	case BMC150_MAGN_POWER_MODE_NORMAL:
> > +		return regmap_update_bits(data->regmap,
> > +					  BMC150_MAGN_REG_OPMODE_ODR,
> > +					  BMC150_MAGN_MASK_OPMODE,
> > +					  BMC150_MAGN_MODE_NORMAL <<
> > +					  BMC150_MAGN_SHIFT_OPMODE);
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> > +
> > +static int bmc150_magn_set_power_state(struct bmc150_magn_data *data, bool on)
> > +{
> > +#ifdef CONFIG_PM
> > +	int ret;
> > +
> > +	if (on) {
> > +		ret = pm_runtime_get_sync(&data->client->dev);
> > +	} else {
> > +		pm_runtime_mark_last_busy(&data->client->dev);
> > +		ret = pm_runtime_put_autosuspend(&data->client->dev);
> > +	}
> > +
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev,
> > +			"failed to change power state to %d\n", on);
> > +		if (on)
> > +			pm_runtime_put_noidle(&data->client->dev);
> > +
> > +		return ret;
> > +	}
> > +#endif
> > +
> > +	return 0;
> > +}
> > +
> > +static int bmc150_magn_get_odr(struct bmc150_magn_data *data, int *val)
> > +{
> > +	int ret, reg_val;
> > +	u8 i, odr_val;
> > +
> > +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_OPMODE_ODR, &reg_val);
> > +	if (ret < 0)
> > +		return ret;
> > +	odr_val = (reg_val & BMC150_MAGN_MASK_ODR) >> BMC150_MAGN_SHIFT_ODR;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++)
> > +		if (bmc150_magn_samp_freq_table[i].reg_val == odr_val) {
> > +			*val = bmc150_magn_samp_freq_table[i].freq;
> > +			return 0;
> > +		}
> > +
> > +	return -EINVAL;
> > +}
> > +
> > +static int bmc150_magn_set_odr(struct bmc150_magn_data *data, int val)
> > +{
> > +	int ret;
> > +	u8 i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++) {
> > +		if (bmc150_magn_samp_freq_table[i].freq == val) {
> > +			ret = regmap_update_bits(data->regmap,
> > +						 BMC150_MAGN_REG_OPMODE_ODR,
> > +						 BMC150_MAGN_MASK_ODR,
> > +						 bmc150_magn_samp_freq_table[i].
> > +						 reg_val <<
> > +						 BMC150_MAGN_SHIFT_ODR);
> > +			if (ret < 0)
> > +				return ret;
> > +			return 0;
> > +		}
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> > +
> > +static s32 bmc150_magn_compensate_x(struct bmc150_magn_trim_regs *tregs, s16 x,
> > +				    u16 rhall)
> > +{
> > +	s16 val;
> > +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
> > +
> > +	if (x == BMC150_MAGN_XY_OVERFLOW_VAL)
> > +		return S32_MIN;
> > +
> > +	if (!rhall)
> > +		rhall = xyz1;
> > +
> > +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
> > +	val = ((s16)((((s32)x) * ((((((((s32)tregs->xy2) * ((((s32)val) *
> > +	      ((s32)val)) >> 7)) + (((s32)val) *
> > +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
> > +	      ((s32)(((s16)tregs->x2) + ((s16)0xA0)))) >> 12)) >> 13)) +
> > +	      (((s16)tregs->x1) << 3);
> > +
> > +	return (s32)val;
> > +}
> > +
> > +static s32 bmc150_magn_compensate_y(struct bmc150_magn_trim_regs *tregs, s16 y,
> > +				    u16 rhall)
> > +{
> > +	s16 val;
> > +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
> > +
> > +	if (y == BMC150_MAGN_XY_OVERFLOW_VAL)
> > +		return S32_MIN;
> > +
> > +	if (!rhall)
> > +		rhall = xyz1;
> > +
> > +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
> > +	val = ((s16)((((s32)y) * ((((((((s32)tregs->xy2) * ((((s32)val) *
> > +	      ((s32)val)) >> 7)) + (((s32)val) *
> > +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
> > +	      ((s32)(((s16)tregs->y2) + ((s16)0xA0)))) >> 12)) >> 13)) +
> > +	      (((s16)tregs->y1) << 3);
> > +
> > +	return (s32)val;
> > +}
> > +
> > +static s32 bmc150_magn_compensate_z(struct bmc150_magn_trim_regs *tregs, s16 z,
> > +				    u16 rhall)
> > +{
> > +	s32 val;
> > +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
> > +	u16 z1 = le16_to_cpu(tregs->z1);
> > +	s16 z2 = le16_to_cpu(tregs->z2);
> > +	s16 z3 = le16_to_cpu(tregs->z3);
> > +	s16 z4 = le16_to_cpu(tregs->z4);
> > +
> > +	if (z == BMC150_MAGN_Z_OVERFLOW_VAL)
> > +		return S32_MIN;
> > +
> > +	val = (((((s32)(z - z4)) << 15) - ((((s32)z3) * ((s32)(((s16)rhall) -
> > +	      ((s16)xyz1)))) >> 2)) / (z2 + ((s16)(((((s32)z1) *
> > +	      ((((s16)rhall) << 1))) + (1 << 15)) >> 16))));
> > +
> > +	return val;
> > +}
> > +
> > +static int bmc150_magn_read_xyz(struct bmc150_magn_data *data, s32 *buffer)
> > +{
> > +	int ret;
> > +	__le16 values[AXIS_XYZR_MAX];
> > +	s16 raw_x, raw_y, raw_z;
> > +	u16 rhall;
> > +	struct bmc150_magn_trim_regs tregs;
> > +
> > +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_X_L,
> > +			       values, sizeof(values));
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	raw_x = (s16)le16_to_cpu(values[AXIS_X]) >> BMC150_MAGN_SHIFT_XY_L;
> > +	raw_y = (s16)le16_to_cpu(values[AXIS_Y]) >> BMC150_MAGN_SHIFT_XY_L;
> > +	raw_z = (s16)le16_to_cpu(values[AXIS_Z]) >> BMC150_MAGN_SHIFT_Z_L;
> > +	rhall = le16_to_cpu(values[RHALL]) >> BMC150_MAGN_SHIFT_RHALL_L;
> > +
> > +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
> > +			       &tregs, sizeof(tregs));
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	buffer[AXIS_X] = bmc150_magn_compensate_x(&tregs, raw_x, rhall);
> > +	buffer[AXIS_Y] = bmc150_magn_compensate_y(&tregs, raw_y, rhall);
> > +	buffer[AXIS_Z] = bmc150_magn_compensate_z(&tregs, raw_z, rhall);
> > +
> > +	return 0;
> > +}
> > +
> > +static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
> > +				struct iio_chan_spec const *chan,
> > +				int *val, int *val2, long mask)
> > +{
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret, tmp;
> > +	s32 values[AXIS_XYZ_MAX];
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:
> > +		if (iio_buffer_enabled(indio_dev))
> > +			return -EBUSY;
> > +		mutex_lock(&data->mutex);
> > +
> > +		ret = bmc150_magn_set_power_state(data, true);
> > +		if (ret < 0)
> You just returned with the mutex held...  Check the other places this might happen please.
Oops... Seems I missed the unlock twice in this function. Thanks for catching this!

> > +			return ret;
> > +
> > +		ret = bmc150_magn_read_xyz(data, values);
> > +		if (ret < 0) {
> > +			bmc150_magn_set_power_state(data, false);
> > +			mutex_unlock(&data->mutex);
> > +			return ret;
> > +		}
> > +		*val = values[chan->scan_index];
> > +
> > +		ret = bmc150_magn_set_power_state(data, false);
> > +		if (ret < 0)
> > +			return ret;
> > +
> > +		mutex_unlock(&data->mutex);
> > +		return IIO_VAL_INT;
> > +	case IIO_CHAN_INFO_SCALE:
> > +		/*
> > +		 * The API/driver performs an off-chip temperature
> > +		 * compensation and outputs x/y/z magnetic field data in
> > +		 * 16 LSB/uT to the upper application layer.
> > +		 */
> > +		*val = 0;
> > +		*val2 = 625;
> > +		return IIO_VAL_INT_PLUS_MICRO;
> > +	case IIO_CHAN_INFO_SAMP_FREQ:
> > +		ret = bmc150_magn_get_odr(data, val);
> > +		if (ret < 0)
> > +			return ret;
> > +		return IIO_VAL_INT;
> > +	case IIO_CHAN_INFO_CALIBREPETITIONS:
> > +		switch (chan->channel2) {
> > +		case IIO_MOD_X:
> > +		case IIO_MOD_Y:
> > +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
> > +					  &tmp);
> > +			if (ret < 0)
> > +				return ret;
> > +			*val = BMC150_MAGN_REGVAL_TO_REPXY(tmp);
> > +			return IIO_VAL_INT;
> > +		case IIO_MOD_Z:
> > +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
> > +					  &tmp);
> > +			if (ret < 0)
> > +				return ret;
> > +			*val = BMC150_MAGN_REGVAL_TO_REPZ(tmp);
> > +			return IIO_VAL_INT;
> > +		default:
> > +			return -EINVAL;
> > +		}
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +}
> > +
> > +static int bmc150_magn_write_raw(struct iio_dev *indio_dev,
> > +				 struct iio_chan_spec const *chan,
> > +				 int val, int val2, long mask)
> > +{
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_SAMP_FREQ:
> > +		mutex_lock(&data->mutex);
> > +		ret = bmc150_magn_set_odr(data, val);
> > +		mutex_unlock(&data->mutex);
> > +		return ret;
> > +	case IIO_CHAN_INFO_CALIBREPETITIONS:
> > +		switch (chan->channel2) {
> > +		case IIO_MOD_X:
> > +		case IIO_MOD_Y:
> > +			if (val < 1 || val > 511)
> > +				return -EINVAL;
> > +			return regmap_update_bits(data->regmap,
> > +						  BMC150_MAGN_REG_REP_XY,
> > +						  0xFF,
> > +						  BMC150_MAGN_REPXY_TO_REGVAL
> > +						  (val));
> > +		case IIO_MOD_Z:
> > +			if (val < 1 || val > 256)
> > +				return -EINVAL;
> > +			return regmap_update_bits(data->regmap,
> > +						  BMC150_MAGN_REG_REP_Z,
> > +						  0xFF,
> > +						  BMC150_MAGN_REPZ_TO_REGVAL
> > +						  (val));
> > +		default:
> > +			return -EINVAL;
> > +		}
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +}
> > +
> > +static int bmc150_magn_validate_trigger(struct iio_dev *indio_dev,
> > +					struct iio_trigger *trig)
> > +{
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +
> > +	if (data->dready_trig != trig)
> > +		return -EINVAL;
> > +
> > +	return 0;
> > +}
> > +
> > +static int bmc150_magn_update_scan_mode(struct iio_dev *indio_dev,
> > +					const unsigned long *scan_mask)
> > +{
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +
> > +	mutex_lock(&data->mutex);
> > +	kfree(data->buffer);
> > +	data->buffer = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
> Call be cynical, but how large can this buffer get?
> 
> I'd just allocate it as part of data in the first place then you
> can drop this function entirely and don't have to clean it up
> separately.
With all channels enabled it is 24 bytes. I'll allocate it with data.

> > +	mutex_unlock(&data->mutex);
> > +
> > +	if (!data->buffer)
> > +		return -ENOMEM;
> > +
> > +	return 0;
> > +}
> > +
> > +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("2 6 8 10 15 20 25 30");
> > +
> > +static struct attribute *bmc150_magn_attributes[] = {
> > +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> > +	NULL,
> > +};
> > +
> > +static const struct attribute_group bmc150_magn_attrs_group = {
> > +	.attrs = bmc150_magn_attributes,
> > +};
> > +
> > +#define BMC150_MAGN_CHANNEL(_axis) {					\
> > +	.type = IIO_MAGN,						\
> > +	.modified = 1,							\
> > +	.channel2 = IIO_MOD_##_axis,					\
> > +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
> > +			      BIT(IIO_CHAN_INFO_CALIBREPETITIONS),	\
> > +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) |	\
> > +				    BIT(IIO_CHAN_INFO_SCALE),		\
> > +	.scan_index = AXIS_##_axis,					\
> > +	.scan_type = {							\
> > +		.sign = 's',						\
> > +		.realbits = 32,						\
> > +		.storagebits = 32,					\
> > +		.shift = 0,						\
> > +		.endianness = IIO_LE					\
> > +	},								\
> > +}
> > +
> > +static const struct iio_chan_spec bmc150_magn_channels[] = {
> > +	BMC150_MAGN_CHANNEL(X),
> > +	BMC150_MAGN_CHANNEL(Y),
> > +	BMC150_MAGN_CHANNEL(Z),
> > +	IIO_CHAN_SOFT_TIMESTAMP(3),
> > +};
> > +
> > +static const struct iio_info bmc150_magn_info = {
> > +	.attrs = &bmc150_magn_attrs_group,
> > +	.read_raw = bmc150_magn_read_raw,
> > +	.write_raw = bmc150_magn_write_raw,
> > +	.validate_trigger = bmc150_magn_validate_trigger,
> > +	.update_scan_mode = bmc150_magn_update_scan_mode,
> > +	.driver_module = THIS_MODULE,
> > +};
> > +
> > +static const unsigned long bmc150_magn_scan_masks[] = {0x07, 0};
> > +
> > +static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
> > +{
> > +	struct iio_poll_func *pf = p;
> > +	struct iio_dev *indio_dev = pf->indio_dev;
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	mutex_lock(&data->mutex);
> > +	ret = bmc150_magn_read_xyz(data, data->buffer);
> > +	mutex_unlock(&data->mutex);
> > +	if (ret < 0)
> > +		goto err;
> > +
> > +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
> > +					   pf->timestamp);
> > +
> > +err:
> > +	iio_trigger_notify_done(data->dready_trig);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int bmc150_magn_init(struct bmc150_magn_data *data)
> > +{
> > +	int ret, chip_id;
> > +	struct bmc150_magn_preset preset;
> > +	struct bmc150_magn_trim_regs tregs;
> > +
> > +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND,
> > +					 false);
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev,
> > +			"Failed to bring up device from suspend mode\n");
> > +		return ret;
> > +	}
> > +
> > +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_CHIP_ID, &chip_id);
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "Failed reading chip id\n");
> > +		goto err_poweroff;
> > +	}
> > +	if (chip_id != BMC150_MAGN_CHIP_ID_VAL) {
> > +		dev_err(&data->client->dev, "Invalid chip id 0x%x\n", ret);
> > +		ret = -ENODEV;
> > +		goto err_poweroff;
> > +	}
> > +	dev_dbg(&data->client->dev, "Chip id %x\n", ret);
> > +
> > +	preset = bmc150_magn_presets_table[BMC150_MAGN_DEFAULT_PRESET];
> > +	ret = bmc150_magn_set_odr(data, preset.odr);
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "Failed to set ODR to %d\n",
> > +			preset.odr);
> > +		goto err_poweroff;
> > +	}
> > +
> > +	ret = regmap_update_bits(data->regmap,
> > +				 BMC150_MAGN_REG_REP_XY,
> > +				 0xFF,
> > +				 BMC150_MAGN_REPXY_TO_REGVAL(preset.rep_xy));
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "Failed to set REP XY to %d\n",
> > +			preset.rep_xy);
> > +		goto err_poweroff;
> > +	}
> > +
> > +	ret = regmap_update_bits(data->regmap,
> > +				 BMC150_MAGN_REG_REP_Z,
> > +				 0xFF,
> Umm. With a mask of 0xFF are we not just setting the whole register?  In which
> case why use update_bits?   regmap_write instead...

I am using regmap_update_bits because it also checks if the value actually changed.
I could use regmap_write here instead, since we are initializing the driver, but
I would keep regmap_update_bits where the value is updated by the user (so we don't
do the i2c transfer if the value did not change).

> > +				 BMC150_MAGN_REPZ_TO_REGVAL(preset.rep_z));
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "Failed to set REP Z to %d\n",
> > +			preset.rep_z);
> > +		goto err_poweroff;
> > +	}
> > +
> > +	/* Cache trim registers in regmap. */
> A little ugly. Is there no way of asking regmap to fill it's cache for certain registers?
> Actually as I read it having taken a quick look, regcache_hw_init will read all your registers
> given you haven't provided defaults.  Hence this will be cached already..
Unfortunately it does not work in this case.
In the current implementation the registers are not cached because num_reg_defaults_raw is not set.
After setting num_reg_defaults_raw, regcache_hw_init will read all registers starting from register
0, but bmc150 magn starts its register map at register 0x40. I am not sure yet how to force a different
stat register value or how to cache the registers in another way.

I will remove the regmap_bulk_read for now, so the actual transfer will be done when the first interrupt
is handled. I will look further into this and come with a follow-up patch when I find a better solution.

> > +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
> > +			       &tregs, sizeof(tregs));
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "Failed to read trim registers\n");
> > +		goto err_poweroff;
> > +	}
> > +
> > +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
> > +					 true);
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "Failed to power on device\n");
> > +		goto err_poweroff;
> > +	}
> > +
> > +	return 0;
> > +
> > +err_poweroff:
> > +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
> > +	return ret;
> > +}
> > +
> > +static int bmc150_magn_reset_intr(struct bmc150_magn_data *data)
> > +{
> > +	int tmp;
> > +
> > +	/*
> > +	 * Data Ready (DRDY) is always cleared after
> > +	 * readout of data registers ends.
> > +	 */
> > +	return regmap_read(data->regmap, BMC150_MAGN_REG_X_L, &tmp);
> Good to see this here.  Often people don't bother on the basis
> of course the driver has already read the data register!
> (which it might not have done if the trigger is being used by another
> device).
> > +}
> > +
> > +static int bmc150_magn_trig_try_reen(struct iio_trigger *trig)
> > +{
> > +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	if (!data->dready_trigger_on)
> > +		return 0;
> > +
> > +	mutex_lock(&data->mutex);
> > +	ret = bmc150_magn_reset_intr(data);
> > +	mutex_unlock(&data->mutex);
> > +
> > +	return ret;
> > +}
> > +
> > +static int bmc150_magn_data_rdy_trigger_set_state(struct iio_trigger *trig,
> > +						  bool state)
> > +{
> > +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret = 0;
> > +
> > +	mutex_lock(&data->mutex);
> > +	if (state == data->dready_trigger_on)
> > +		goto err_unlock;
> > +
> > +	ret = bmc150_magn_set_power_state(data, state);
> > +	if (ret < 0)
> > +		goto err_unlock;
> > +
> > +	ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_INT_DRDY,
> > +				 BMC150_MAGN_MASK_DRDY_EN,
> > +				 state << BMC150_MAGN_SHIFT_DRDY_EN);
> > +	if (ret < 0)
> > +		goto err_poweroff;
> > +
> > +	data->dready_trigger_on = state;
> > +
> > +	if (state) {
> > +		ret = bmc150_magn_reset_intr(data);
> > +		if (ret < 0)
> > +			goto err_poweroff;
> > +	}
> > +	mutex_unlock(&data->mutex);
> > +
> > +	return 0;
> > +
> > +err_poweroff:
> > +	bmc150_magn_set_power_state(data, false);
> > +err_unlock:
> > +	mutex_unlock(&data->mutex);
> > +	return ret;
> > +}
> > +
> > +static const struct iio_trigger_ops bmc150_magn_trigger_ops = {
> > +	.set_trigger_state = bmc150_magn_data_rdy_trigger_set_state,
> > +	.try_reenable = bmc150_magn_trig_try_reen,
> > +	.owner = THIS_MODULE,
> > +};
> > +
> > +static int bmc150_magn_gpio_probe(struct i2c_client *client)
> > +{
> > +	struct device *dev;
> > +	struct gpio_desc *gpio;
> > +	int ret;
> > +
> > +	if (!client)
> > +		return -EINVAL;
> > +
> > +	dev = &client->dev;
> > +
> > +	/* data ready GPIO interrupt pin */
> > +	gpio = devm_gpiod_get_index(dev, BMC150_MAGN_GPIO_INT, 0);
> > +	if (IS_ERR(gpio)) {
> > +		dev_err(dev, "ACPI GPIO get index failed\n");
> > +		return PTR_ERR(gpio);
> > +	}
> > +
> > +	ret = gpiod_direction_input(gpio);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = gpiod_to_irq(gpio);
> > +
> > +	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
> > +
> > +	return ret;
> > +}
> > +
> > +static const char *bmc150_magn_match_acpi_device(struct device *dev)
> > +{
> > +	const struct acpi_device_id *id;
> > +
> > +	id = acpi_match_device(dev->driver->acpi_match_table, dev);
> > +	if (!id)
> > +		return NULL;
> > +
> > +	return dev_name(dev);
> > +}
> > +
> > +static int bmc150_magn_probe(struct i2c_client *client,
> > +			     const struct i2c_device_id *id)
> > +{
> > +	struct bmc150_magn_data *data;
> > +	struct iio_dev *indio_dev;
> > +	const char *name = NULL;
> > +	int ret;
> > +
> > +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	data = iio_priv(indio_dev);
> > +	i2c_set_clientdata(client, indio_dev);
> > +	data->client = client;
> > +
> > +	if (id)
> > +		name = id->name;
> > +	else if (ACPI_HANDLE(&client->dev))
> > +		name = bmc150_magn_match_acpi_device(&client->dev);
> > +	else
> > +		return -ENOSYS;
> > +
> > +	mutex_init(&data->mutex);
> > +	data->regmap = devm_regmap_init_i2c(client, &bmc150_magn_regmap_config);
> > +	if (IS_ERR(data->regmap)) {
> > +		dev_err(&client->dev, "Failed to allocate register map\n");
> > +		return PTR_ERR(data->regmap);
> > +	}
> > +
> > +	ret = bmc150_magn_init(data);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	indio_dev->dev.parent = &client->dev;
> > +	indio_dev->channels = bmc150_magn_channels;
> > +	indio_dev->num_channels = ARRAY_SIZE(bmc150_magn_channels);
> > +	indio_dev->available_scan_masks = bmc150_magn_scan_masks;
> > +	indio_dev->name = name;
> > +	indio_dev->modes = INDIO_DIRECT_MODE;
> > +	indio_dev->info = &bmc150_magn_info;
> > +
> > +	if (client->irq <= 0)
> > +		client->irq = bmc150_magn_gpio_probe(client);
> > +
> > +	if (client->irq > 0) {
> > +		data->dready_trig = devm_iio_trigger_alloc(&client->dev,
> > +							   "%s-dev%d",
> > +							   indio_dev->name,
> > +							   indio_dev->id);
> > +		if (!data->dready_trig) {
> > +			ret = -ENOMEM;
> > +			dev_err(&client->dev, "iio trigger alloc failed\n");
> > +			goto err_poweroff;
> > +		}
> > +
> > +		data->dready_trig->dev.parent = &client->dev;
> > +		data->dready_trig->ops = &bmc150_magn_trigger_ops;
> > +		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
> > +		ret = iio_trigger_register(data->dready_trig);
> > +		if (ret) {
> > +			dev_err(&client->dev, "iio trigger register failed\n");
> > +			goto err_poweroff;
> > +		}
> > +
> > +		ret = iio_triggered_buffer_setup(indio_dev,
> > +						 &iio_pollfunc_store_time,
> > +						 bmc150_magn_trigger_handler,
> > +						 NULL);
> > +		if (ret < 0) {
> > +			dev_err(&client->dev,
> > +				"iio triggered buffer setup failed\n");
> > +			goto err_trigger_unregister;
> > +		}
> > +
> > +		ret = devm_request_threaded_irq(&client->dev, client->irq,
> > +					     iio_trigger_generic_data_rdy_poll,
> > +					     NULL,
> > +					     IRQF_TRIGGER_RISING | IRQF_ONESHOT,
> > +					     BMC150_MAGN_IRQ_NAME,
> > +					     data->dready_trig);
> > +		if (ret < 0) {
> > +			dev_err(&client->dev, "request irq %d failed\n",
> > +				client->irq);
> > +			goto err_buffer_cleanup;
> > +		}
> > +	}
> > +
> > +	ret = iio_device_register(indio_dev);
> > +	if (ret < 0) {
> > +		dev_err(&client->dev, "unable to register iio device\n");
> > +		goto err_buffer_cleanup;
> > +	}
> > +
> > +	ret = pm_runtime_set_active(&client->dev);
> > +	if (ret)
> > +		goto err_iio_unregister;
> > +
> > +	pm_runtime_enable(&client->dev);
> > +	pm_runtime_set_autosuspend_delay(&client->dev,
> > +					 BMC150_MAGN_AUTO_SUSPEND_DELAY_MS);
> > +	pm_runtime_use_autosuspend(&client->dev);
> > +
> > +	dev_dbg(&indio_dev->dev, "Registered device %s\n", name);
> > +
> > +	return 0;
> > +
> > +err_iio_unregister:
> > +	iio_device_unregister(indio_dev);
> > +err_buffer_cleanup:
> 
> Hmm. There is an issue with this being obviously correct.
> The unwind ordering different from setup.
> Because you have devm_request_threaded_irq calls they will unwind only after these
> calls, but should occur before.
> Now it probaby makes no difference, but it does fail the obviously correct test.
> 
> It's also the case in the remove.  I'd be inclined not to use the devm versin
> of the irq request, but do it explicitly. This one comes up a lot and much like
> the devm_iio_register_device call it's only really a good idea if everything
> is managed.  In mixed cases, I'd avoid it.
> 
I agree. I will use request_threaded_irq instead.

> Maybe I'm just being overly fussy...
> 
> > +	if (data->dready_trig)
> > +		iio_triggered_buffer_cleanup(indio_dev);
> > +err_trigger_unregister:
> > +	if (data->dready_trig)
> > +		iio_trigger_unregister(data->dready_trig);
> > +err_poweroff:
> > +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
> > +	return ret;
> > +}
> > +
> > +static int bmc150_magn_remove(struct i2c_client *client)
> > +{
> > +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +
> > +	pm_runtime_disable(&client->dev);
> > +	pm_runtime_set_suspended(&client->dev);
> > +	pm_runtime_put_noidle(&client->dev);
> > +
> > +	iio_device_unregister(indio_dev);
> > +
> > +	if (data->dready_trig) {
> > +		iio_triggered_buffer_cleanup(indio_dev);
> > +		iio_trigger_unregister(data->dready_trig);
> > +	}
> As mentioned above, this clean up isn't needed if you simply
> always make data->buffer the largest size it can ever be.
Yes, I will remove this after allocating the data->buffer with data.
> > +	kfree(data->buffer);
> > +
> > +	mutex_lock(&data->mutex);
> > +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
> > +	mutex_unlock(&data->mutex);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_PM
> > +static int bmc150_magn_runtime_suspend(struct device *dev)
> > +{
> > +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	mutex_lock(&data->mutex);
> > +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
> > +					 true);
> > +	mutex_unlock(&data->mutex);
> > +	if (ret < 0) {
> > +		dev_err(&data->client->dev, "powering off device failed\n");
> > +		return -EAGAIN;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int bmc150_magn_runtime_resume(struct device *dev)
> > +{
> > +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +
> > +	return bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
> > +					  true);
> > +}
> > +#endif
> > +
> > +#ifdef CONFIG_PM_SLEEP
> > +static int bmc150_magn_suspend(struct device *dev)
> > +{
> > +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	mutex_lock(&data->mutex);
> > +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
> > +					 true);
> > +	mutex_unlock(&data->mutex);
> > +
> > +	return ret;
> > +}
> > +
> > +static int bmc150_magn_resume(struct device *dev)
> > +{
> > +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
> > +	struct bmc150_magn_data *data = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	mutex_lock(&data->mutex);
> > +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
> > +					 true);
> > +	mutex_unlock(&data->mutex);
> > +
> > +	return ret;
> > +}
> > +#endif
> > +
> > +static const struct dev_pm_ops bmc150_magn_pm_ops = {
> > +	SET_SYSTEM_SLEEP_PM_OPS(bmc150_magn_suspend, bmc150_magn_resume)
> > +	SET_RUNTIME_PM_OPS(bmc150_magn_runtime_suspend,
> > +			   bmc150_magn_runtime_resume, NULL)
> > +};
> > +
> > +static const struct acpi_device_id bmc150_magn_acpi_match[] = {
> > +	{"BMC150B", 0},
> > +	{},
> > +};
> nitpick, no blank line here. Tends to directly associate the structure
> with the following macro which is visually nice..
Sure, I will remove all blank lines you mentioned.
> > +
> > +MODULE_DEVICE_TABLE(acpi, bmc150_magn_acpi_match);
> > +
> > +static const struct i2c_device_id bmc150_magn_id[] = {
> > +	{"bmc150_magn", 0},
> > +	{},
> > +};
> Nitpick, no blank line.
> > +
> > +MODULE_DEVICE_TABLE(i2c, bmc150_magn_id);
> > +
> > +static struct i2c_driver bmc150_magn_driver = {
> > +	.driver = {
> > +		   .name = BMC150_MAGN_DRV_NAME,
> > +		   .acpi_match_table = ACPI_PTR(bmc150_magn_acpi_match),
> > +		   .pm = &bmc150_magn_pm_ops,
> > +		   },
> > +	.probe = bmc150_magn_probe,
> > +	.remove = bmc150_magn_remove,
> > +	.id_table = bmc150_magn_id,
> > +};
> Nitpick. I'd not bother with the blank line here.
> > +
> > +module_i2c_driver(bmc150_magn_driver);
> > +
> > +MODULE_AUTHOR("Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_DESCRIPTION("BMC150 magnetometer driver");
> >

Re: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer

[Jonathan Cameron]

On 22/04/15 13:45, Tirdea, Irina wrote:
> 
> 
>> -----Original Message-----
>> From: Jonathan Cameron [mailto:jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org]
>> Sent: 18 April, 2015 21:07
>> To: Tirdea, Irina; linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Hartmut Knaack; Lars-Peter Clausen; Peter Meerwald; Rob Herring; Pawel Moll; Mark Rutland; Ian
>> Campbell; Kumar Gala
>> Subject: Re: [PATCH 2/3] iio: magn: Add support for BMC150 magnetometer
>>
>> On 17/04/15 11:50, Irina Tirdea wrote:
>>> Add support for the Bosh BMC150 Magnetometer.
>>> The specification can be downloaded from:
>>> http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf.
>>> The chip contains both an accelerometer and a magnetometer.
>>> This patch adds support only for the magnetometer part.
>>>
>>> The temperature compensation formulas are based on bmm050_api.c
>>> authored by contact-oifgY8usX4GOK76mbL0HZ+jAqQFK86Wj@public.gmane.org
>>>
>>> Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>> Generally looks good, but a few odd bits and pieces...
> 
> Thanks for the review, Jonathan!
> 
>> Quite a few places you use regmap_update_bits to write with a mask of 0xFF
>> which seems odd..
>>
> The idea there is to not do unnecessary i2c_reads/writes if the value does not change:
> regmap_update_bits will check the cached value and only do the i2c transfer if the value 
> did not change.
Odd that regmap_write doesn't check the cache as well, or that we don't have a cleaner
means of doing this but fair enough. Cc'd Mark Brown in case he has any views on this.
>  
>> Various other bits inline.
>>> ---
>>>  drivers/iio/magnetometer/Kconfig       |   14 +
>>>  drivers/iio/magnetometer/Makefile      |    2 +
>>>  drivers/iio/magnetometer/bmc150_magn.c | 1060 ++++++++++++++++++++++++++++++++
>>>  3 files changed, 1076 insertions(+)
>>>  create mode 100644 drivers/iio/magnetometer/bmc150_magn.c
>>>
>>> diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
>>> index a5d6de7..008baca 100644
>>> --- a/drivers/iio/magnetometer/Kconfig
>>> +++ b/drivers/iio/magnetometer/Kconfig
>>> @@ -76,4 +76,18 @@ config IIO_ST_MAGN_SPI_3AXIS
>>>  	depends on IIO_ST_MAGN_3AXIS
>>>  	depends on IIO_ST_SENSORS_SPI
>>>
>>> +config BMC150_MAGN
>>> +	tristate "Bosch BMC150 Magnetometer Driver"
>>> +	depends on I2C
>>> +	select IIO_BUFFER
>>> +	select IIO_TRIGGERED_BUFFER
>>> +	help
>>> +	  Say yes here to build support for the BMC150 magnetometer.
>>> +
>>> +	  Currently this only supports the device via an i2c interface.
>>> +
>>> +	  This is a combo module with both accelerometer and magnetometer.
>>> +	  This driver is only implementing magnetometer part, which has
>>> +	  its own address and register map.
>>> +
>>>  endmenu
>>> diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
>>> index 0f5d3c9..e2c3459 100644
>>> --- a/drivers/iio/magnetometer/Makefile
>>> +++ b/drivers/iio/magnetometer/Makefile
>>> @@ -13,3 +13,5 @@ st_magn-$(CONFIG_IIO_BUFFER) += st_magn_buffer.o
>>>
>>>  obj-$(CONFIG_IIO_ST_MAGN_I2C_3AXIS) += st_magn_i2c.o
>>>  obj-$(CONFIG_IIO_ST_MAGN_SPI_3AXIS) += st_magn_spi.o
>>> +
>>> +obj-$(CONFIG_BMC150_MAGN) += bmc150_magn.o
>>> diff --git a/drivers/iio/magnetometer/bmc150_magn.c b/drivers/iio/magnetometer/bmc150_magn.c
>>> new file mode 100644
>>> index 0000000..e970a0c
>>> --- /dev/null
>>> +++ b/drivers/iio/magnetometer/bmc150_magn.c
>>> @@ -0,0 +1,1060 @@
>>> +/*
>>> + * Bosch BMC150 three-axis magnetic field sensor driver
>>> + *
>>> + * Copyright (c) 2015, Intel Corporation.
>>> + *
>>> + * This code is based on bmm050_api.c authored by contact-oifgY8usX4GOK76mbL0HZ0EOCMrvLtNR@public.gmane.org:
>>> + *
>>> + * (C) Copyright 2011~2014 Bosch Sensortec GmbH All Rights Reserved
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify it
>>> + * under the terms and conditions of the GNU General Public License,
>>> + * version 2, as published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope it will be useful, but WITHOUT
>>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>>> + * more details.
>>> + */
>>> +
>>> +#include <linux/module.h>
>>> +#include <linux/i2c.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/delay.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/acpi.h>
>>> +#include <linux/gpio/consumer.h>
>>> +#include <linux/pm.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/iio/iio.h>
>>> +#include <linux/iio/sysfs.h>
>>> +#include <linux/iio/buffer.h>
>>> +#include <linux/iio/events.h>
>>> +#include <linux/iio/trigger.h>
>>> +#include <linux/iio/trigger_consumer.h>
>>> +#include <linux/iio/triggered_buffer.h>
>>> +#include <linux/regmap.h>
>>> +
>>> +#define BMC150_MAGN_DRV_NAME			"bmc150_magn"
>>> +#define BMC150_MAGN_IRQ_NAME			"bmc150_magn_event"
>>> +#define BMC150_MAGN_GPIO_INT			"interrupt"
>>> +
>>> +#define BMC150_MAGN_REG_CHIP_ID			0x40
>>> +#define BMC150_MAGN_CHIP_ID_VAL			0x32
>>> +
>>> +#define BMC150_MAGN_REG_X_L			0x42
>>> +#define BMC150_MAGN_REG_X_M			0x43
>>> +#define BMC150_MAGN_REG_Y_L			0x44
>>> +#define BMC150_MAGN_REG_Y_M			0x45
>>> +#define BMC150_MAGN_SHIFT_XY_L			3
>>> +#define BMC150_MAGN_REG_Z_L			0x46
>>> +#define BMC150_MAGN_REG_Z_M			0x47
>>> +#define BMC150_MAGN_SHIFT_Z_L			1
>>> +#define BMC150_MAGN_REG_RHALL_L			0x48
>>> +#define BMC150_MAGN_REG_RHALL_M			0x49
>>> +#define BMC150_MAGN_SHIFT_RHALL_L		2
>>> +
>>> +#define BMC150_MAGN_REG_INT_STATUS		0x4A
>>> +
>>> +#define BMC150_MAGN_REG_POWER			0x4B
>>> +#define BMC150_MAGN_MASK_POWER_CTL		BIT(0)
>>> +
>>> +#define BMC150_MAGN_REG_OPMODE_ODR		0x4C
>>> +#define BMC150_MAGN_MASK_OPMODE			GENMASK(2, 1)
>>> +#define BMC150_MAGN_SHIFT_OPMODE		1
>>> +#define BMC150_MAGN_MODE_NORMAL			0x00
>>> +#define BMC150_MAGN_MODE_FORCED			0x01
>>> +#define BMC150_MAGN_MODE_SLEEP			0x03
>>> +#define BMC150_MAGN_MASK_ODR			GENMASK(5, 3)
>>> +#define BMC150_MAGN_SHIFT_ODR			3
>>> +
>>> +#define BMC150_MAGN_REG_INT			0x4D
>>> +
>>> +#define BMC150_MAGN_REG_INT_DRDY		0x4E
>>> +#define BMC150_MAGN_MASK_DRDY_EN		BIT(7)
>>> +#define BMC150_MAGN_SHIFT_DRDY_EN		7
>>> +#define BMC150_MAGN_MASK_DRDY_INT3		BIT(6)
>>> +#define BMC150_MAGN_MASK_DRDY_Z_EN		BIT(5)
>>> +#define BMC150_MAGN_MASK_DRDY_Y_EN		BIT(4)
>>> +#define BMC150_MAGN_MASK_DRDY_X_EN		BIT(3)
>>> +#define BMC150_MAGN_MASK_DRDY_DR_POLARITY	BIT(2)
>>> +#define BMC150_MAGN_MASK_DRDY_LATCHING		BIT(1)
>>> +#define BMC150_MAGN_MASK_DRDY_INT3_POLARITY	BIT(0)
>>> +
>>> +#define BMC150_MAGN_REG_LOW_THRESH		0x4F
>>> +#define BMC150_MAGN_REG_HIGH_THRESH		0x50
>>> +#define BMC150_MAGN_REG_REP_XY			0x51
>>> +#define BMC150_MAGN_REG_REP_Z			0x52
>>> +
>>> +#define BMC150_MAGN_REG_TRIM_START		0x5D
>>> +#define BMC150_MAGN_REG_TRIM_END		0x71
>>> +
>>> +#define BMC150_MAGN_XY_OVERFLOW_VAL		-4096
>>> +#define BMC150_MAGN_Z_OVERFLOW_VAL		-16384
>>> +
>>> +/* Time from SUSPEND to SLEEP */
>>> +#define BMC150_MAGN_START_UP_TIME_MS		3
>>> +
>>> +#define BMC150_MAGN_AUTO_SUSPEND_DELAY_MS	2000
>>> +
>>> +#define BMC150_MAGN_REGVAL_TO_REPXY(regval) (((regval) * 2) + 1)
>>> +#define BMC150_MAGN_REGVAL_TO_REPZ(regval) ((regval) + 1)
>>> +#define BMC150_MAGN_REPXY_TO_REGVAL(rep) (((rep) - 1) / 2)
>>> +#define BMC150_MAGN_REPZ_TO_REGVAL(rep) ((rep) - 1)
>>> +
>>> +enum bmc150_magn_axis {
>>> +	AXIS_X,
>>> +	AXIS_Y,
>>> +	AXIS_Z,
>>> +	RHALL,
>>> +	AXIS_XYZ_MAX = RHALL,
>>> +	AXIS_XYZR_MAX,
>>> +};
>>> +
>>> +enum bmc150_magn_power_modes {
>>> +	BMC150_MAGN_POWER_MODE_SUSPEND,
>>> +	BMC150_MAGN_POWER_MODE_SLEEP,
>>> +	BMC150_MAGN_POWER_MODE_NORMAL,
>>> +};
>>> +
>>> +struct bmc150_magn_trim_regs {
>>> +	s8 x1;
>>> +	s8 y1;
>>> +	__le16 reserved1;
>>> +	u8 reserved2;
>>> +	__le16 z4;
>>> +	s8 x2;
>>> +	s8 y2;
>>> +	__le16 reserved3;
>>> +	__le16 z2;
>>> +	__le16 z1;
>>> +	__le16 xyz1;
>>> +	__le16 z3;
>>> +	s8 xy2;
>>> +	u8 xy1;
>>> +} __packed;
>>> +
>>> +struct bmc150_magn_data {
>>> +	struct i2c_client *client;
>>> +	/*
>>> +	 * 1. Protect this structure.
>>> +	 * 2. Serialize sequences that power on/off the device and access HW.
>>> +	 */
>>> +	struct mutex mutex;
>>> +	struct regmap *regmap;
>>> +	s32 *buffer;
>>> +	struct iio_trigger *dready_trig;
>>> +	bool dready_trigger_on;
>>> +};
>>> +
>>> +static const struct {
>>> +	int freq;
>>> +	u8 reg_val;
>>> +} bmc150_magn_samp_freq_table[] = { {10, 0x00},
>>> +				    {2, 0x01},
>>> +				    {6, 0x02},
>>> +				    {8, 0x03},
>>> +				    {15, 0x04},
>>> +				    {20, 0x05},
>>> +				    {25, 0x06},
>>> +				    {30, 0x07} };
>>> +
>>> +enum bmc150_magn_presets {
>>> +	LOW_POWER_PRESET,
>>> +	REGULAR_PRESET,
>>> +	ENHANCED_REGULAR_PRESET,
>>> +	HIGH_ACCURACY_PRESET
>>> +};
>>> +
>>> +static const struct bmc150_magn_preset {
>>> +	u8 rep_xy;
>>> +	u8 rep_z;
>>> +	u8 odr;
>>> +} bmc150_magn_presets_table[] = {
>>> +	[LOW_POWER_PRESET] = {3, 3, 10},
>>> +	[REGULAR_PRESET] =  {9, 15, 10},
>>> +	[ENHANCED_REGULAR_PRESET] =  {15, 27, 10},
>>> +	[HIGH_ACCURACY_PRESET] =  {47, 83, 20},
>>> +};
>>> +
>>> +#define BMC150_MAGN_DEFAULT_PRESET REGULAR_PRESET
>>> +
>>> +static bool bmc150_magn_is_writeable_reg(struct device *dev, unsigned int reg)
>>> +{
>>> +	switch (reg) {
>>> +	case BMC150_MAGN_REG_POWER:
>>> +	case BMC150_MAGN_REG_OPMODE_ODR:
>>> +	case BMC150_MAGN_REG_INT:
>>> +	case BMC150_MAGN_REG_INT_DRDY:
>>> +	case BMC150_MAGN_REG_LOW_THRESH:
>>> +	case BMC150_MAGN_REG_HIGH_THRESH:
>>> +	case BMC150_MAGN_REG_REP_XY:
>>> +	case BMC150_MAGN_REG_REP_Z:
>>> +		return true;
>>> +	default:
>>> +		return false;
>>> +	};
>>> +}
>>> +
>>> +static bool bmc150_magn_is_volatile_reg(struct device *dev, unsigned int reg)
>>> +{
>>> +	switch (reg) {
>>> +	case BMC150_MAGN_REG_X_L:
>>> +	case BMC150_MAGN_REG_X_M:
>>> +	case BMC150_MAGN_REG_Y_L:
>>> +	case BMC150_MAGN_REG_Y_M:
>>> +	case BMC150_MAGN_REG_Z_L:
>>> +	case BMC150_MAGN_REG_Z_M:
>>> +	case BMC150_MAGN_REG_RHALL_L:
>>> +	case BMC150_MAGN_REG_RHALL_M:
>>> +	case BMC150_MAGN_REG_INT_STATUS:
>>> +		return true;
>>> +	default:
>>> +		return false;
>>> +	}
>>> +}
>>> +
>>> +static const struct regmap_config bmc150_magn_regmap_config = {
>>> +	.reg_bits = 8,
>>> +	.val_bits = 8,
>>> +
>>> +	.max_register = BMC150_MAGN_REG_TRIM_END,
>>> +	.cache_type = REGCACHE_RBTREE,
>>> +
>>> +	.writeable_reg = bmc150_magn_is_writeable_reg,
>>> +	.volatile_reg = bmc150_magn_is_volatile_reg,
>>> +};
>>> +
>> Why bother with this? It's only called in one place and then with a constant so you'll
>> always get the top option.
> 
> Indeed. I thought I will have multiple usages, but now it does not make sense anymore.
> I will remove it and use usleep_range instead.
> 
>>> +static void bmc150_magn_sleep(int sleep_time_ms)
>>> +{
>>> +	if (sleep_time_ms < 20)
>>> +		usleep_range(sleep_time_ms * 1000, 20000);
>>> +	else
>>> +		msleep_interruptible(sleep_time_ms);
>>> +}
>>> +
>>> +static int bmc150_magn_set_power_mode(struct bmc150_magn_data *data,
>>> +				      enum bmc150_magn_power_modes mode,
>>> +				      bool state)
>>> +{
>>> +	int ret;
>>> +
>>> +	switch (mode) {
>>> +	case BMC150_MAGN_POWER_MODE_SUSPEND:
>>> +		ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_POWER,
>>> +					 BMC150_MAGN_MASK_POWER_CTL, !state);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +		bmc150_magn_sleep(BMC150_MAGN_START_UP_TIME_MS);
>>> +		return 0;
>>> +	case BMC150_MAGN_POWER_MODE_SLEEP:
>>> +		return regmap_update_bits(data->regmap,
>>> +					  BMC150_MAGN_REG_OPMODE_ODR,
>>> +					  BMC150_MAGN_MASK_OPMODE,
>>> +					  BMC150_MAGN_MODE_SLEEP <<
>>> +					  BMC150_MAGN_SHIFT_OPMODE);
>>> +	case BMC150_MAGN_POWER_MODE_NORMAL:
>>> +		return regmap_update_bits(data->regmap,
>>> +					  BMC150_MAGN_REG_OPMODE_ODR,
>>> +					  BMC150_MAGN_MASK_OPMODE,
>>> +					  BMC150_MAGN_MODE_NORMAL <<
>>> +					  BMC150_MAGN_SHIFT_OPMODE);
>>> +	}
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static int bmc150_magn_set_power_state(struct bmc150_magn_data *data, bool on)
>>> +{
>>> +#ifdef CONFIG_PM
>>> +	int ret;
>>> +
>>> +	if (on) {
>>> +		ret = pm_runtime_get_sync(&data->client->dev);
>>> +	} else {
>>> +		pm_runtime_mark_last_busy(&data->client->dev);
>>> +		ret = pm_runtime_put_autosuspend(&data->client->dev);
>>> +	}
>>> +
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev,
>>> +			"failed to change power state to %d\n", on);
>>> +		if (on)
>>> +			pm_runtime_put_noidle(&data->client->dev);
>>> +
>>> +		return ret;
>>> +	}
>>> +#endif
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_get_odr(struct bmc150_magn_data *data, int *val)
>>> +{
>>> +	int ret, reg_val;
>>> +	u8 i, odr_val;
>>> +
>>> +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_OPMODE_ODR, &reg_val);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +	odr_val = (reg_val & BMC150_MAGN_MASK_ODR) >> BMC150_MAGN_SHIFT_ODR;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++)
>>> +		if (bmc150_magn_samp_freq_table[i].reg_val == odr_val) {
>>> +			*val = bmc150_magn_samp_freq_table[i].freq;
>>> +			return 0;
>>> +		}
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static int bmc150_magn_set_odr(struct bmc150_magn_data *data, int val)
>>> +{
>>> +	int ret;
>>> +	u8 i;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(bmc150_magn_samp_freq_table); i++) {
>>> +		if (bmc150_magn_samp_freq_table[i].freq == val) {
>>> +			ret = regmap_update_bits(data->regmap,
>>> +						 BMC150_MAGN_REG_OPMODE_ODR,
>>> +						 BMC150_MAGN_MASK_ODR,
>>> +						 bmc150_magn_samp_freq_table[i].
>>> +						 reg_val <<
>>> +						 BMC150_MAGN_SHIFT_ODR);
>>> +			if (ret < 0)
>>> +				return ret;
>>> +			return 0;
>>> +		}
>>> +	}
>>> +
>>> +	return -EINVAL;
>>> +}
>>> +
>>> +static s32 bmc150_magn_compensate_x(struct bmc150_magn_trim_regs *tregs, s16 x,
>>> +				    u16 rhall)
>>> +{
>>> +	s16 val;
>>> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
>>> +
>>> +	if (x == BMC150_MAGN_XY_OVERFLOW_VAL)
>>> +		return S32_MIN;
>>> +
>>> +	if (!rhall)
>>> +		rhall = xyz1;
>>> +
>>> +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
>>> +	val = ((s16)((((s32)x) * ((((((((s32)tregs->xy2) * ((((s32)val) *
>>> +	      ((s32)val)) >> 7)) + (((s32)val) *
>>> +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
>>> +	      ((s32)(((s16)tregs->x2) + ((s16)0xA0)))) >> 12)) >> 13)) +
>>> +	      (((s16)tregs->x1) << 3);
>>> +
>>> +	return (s32)val;
>>> +}
>>> +
>>> +static s32 bmc150_magn_compensate_y(struct bmc150_magn_trim_regs *tregs, s16 y,
>>> +				    u16 rhall)
>>> +{
>>> +	s16 val;
>>> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
>>> +
>>> +	if (y == BMC150_MAGN_XY_OVERFLOW_VAL)
>>> +		return S32_MIN;
>>> +
>>> +	if (!rhall)
>>> +		rhall = xyz1;
>>> +
>>> +	val = ((s16)(((u16)((((s32)xyz1) << 14) / rhall)) - ((u16)0x4000)));
>>> +	val = ((s16)((((s32)y) * ((((((((s32)tregs->xy2) * ((((s32)val) *
>>> +	      ((s32)val)) >> 7)) + (((s32)val) *
>>> +	      ((s32)(((s16)tregs->xy1) << 7)))) >> 9) + ((s32)0x100000)) *
>>> +	      ((s32)(((s16)tregs->y2) + ((s16)0xA0)))) >> 12)) >> 13)) +
>>> +	      (((s16)tregs->y1) << 3);
>>> +
>>> +	return (s32)val;
>>> +}
>>> +
>>> +static s32 bmc150_magn_compensate_z(struct bmc150_magn_trim_regs *tregs, s16 z,
>>> +				    u16 rhall)
>>> +{
>>> +	s32 val;
>>> +	u16 xyz1 = le16_to_cpu(tregs->xyz1);
>>> +	u16 z1 = le16_to_cpu(tregs->z1);
>>> +	s16 z2 = le16_to_cpu(tregs->z2);
>>> +	s16 z3 = le16_to_cpu(tregs->z3);
>>> +	s16 z4 = le16_to_cpu(tregs->z4);
>>> +
>>> +	if (z == BMC150_MAGN_Z_OVERFLOW_VAL)
>>> +		return S32_MIN;
>>> +
>>> +	val = (((((s32)(z - z4)) << 15) - ((((s32)z3) * ((s32)(((s16)rhall) -
>>> +	      ((s16)xyz1)))) >> 2)) / (z2 + ((s16)(((((s32)z1) *
>>> +	      ((((s16)rhall) << 1))) + (1 << 15)) >> 16))));
>>> +
>>> +	return val;
>>> +}
>>> +
>>> +static int bmc150_magn_read_xyz(struct bmc150_magn_data *data, s32 *buffer)
>>> +{
>>> +	int ret;
>>> +	__le16 values[AXIS_XYZR_MAX];
>>> +	s16 raw_x, raw_y, raw_z;
>>> +	u16 rhall;
>>> +	struct bmc150_magn_trim_regs tregs;
>>> +
>>> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_X_L,
>>> +			       values, sizeof(values));
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	raw_x = (s16)le16_to_cpu(values[AXIS_X]) >> BMC150_MAGN_SHIFT_XY_L;
>>> +	raw_y = (s16)le16_to_cpu(values[AXIS_Y]) >> BMC150_MAGN_SHIFT_XY_L;
>>> +	raw_z = (s16)le16_to_cpu(values[AXIS_Z]) >> BMC150_MAGN_SHIFT_Z_L;
>>> +	rhall = le16_to_cpu(values[RHALL]) >> BMC150_MAGN_SHIFT_RHALL_L;
>>> +
>>> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
>>> +			       &tregs, sizeof(tregs));
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	buffer[AXIS_X] = bmc150_magn_compensate_x(&tregs, raw_x, rhall);
>>> +	buffer[AXIS_Y] = bmc150_magn_compensate_y(&tregs, raw_y, rhall);
>>> +	buffer[AXIS_Z] = bmc150_magn_compensate_z(&tregs, raw_z, rhall);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_read_raw(struct iio_dev *indio_dev,
>>> +				struct iio_chan_spec const *chan,
>>> +				int *val, int *val2, long mask)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret, tmp;
>>> +	s32 values[AXIS_XYZ_MAX];
>>> +
>>> +	switch (mask) {
>>> +	case IIO_CHAN_INFO_RAW:
>>> +		if (iio_buffer_enabled(indio_dev))
>>> +			return -EBUSY;
>>> +		mutex_lock(&data->mutex);
>>> +
>>> +		ret = bmc150_magn_set_power_state(data, true);
>>> +		if (ret < 0)
>> You just returned with the mutex held...  Check the other places this might happen please.
> Oops... Seems I missed the unlock twice in this function. Thanks for catching this!
> 
>>> +			return ret;
>>> +
>>> +		ret = bmc150_magn_read_xyz(data, values);
>>> +		if (ret < 0) {
>>> +			bmc150_magn_set_power_state(data, false);
>>> +			mutex_unlock(&data->mutex);
>>> +			return ret;
>>> +		}
>>> +		*val = values[chan->scan_index];
>>> +
>>> +		ret = bmc150_magn_set_power_state(data, false);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +
>>> +		mutex_unlock(&data->mutex);
>>> +		return IIO_VAL_INT;
>>> +	case IIO_CHAN_INFO_SCALE:
>>> +		/*
>>> +		 * The API/driver performs an off-chip temperature
>>> +		 * compensation and outputs x/y/z magnetic field data in
>>> +		 * 16 LSB/uT to the upper application layer.
>>> +		 */
>>> +		*val = 0;
>>> +		*val2 = 625;
>>> +		return IIO_VAL_INT_PLUS_MICRO;
>>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>>> +		ret = bmc150_magn_get_odr(data, val);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +		return IIO_VAL_INT;
>>> +	case IIO_CHAN_INFO_CALIBREPETITIONS:
>>> +		switch (chan->channel2) {
>>> +		case IIO_MOD_X:
>>> +		case IIO_MOD_Y:
>>> +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_XY,
>>> +					  &tmp);
>>> +			if (ret < 0)
>>> +				return ret;
>>> +			*val = BMC150_MAGN_REGVAL_TO_REPXY(tmp);
>>> +			return IIO_VAL_INT;
>>> +		case IIO_MOD_Z:
>>> +			ret = regmap_read(data->regmap, BMC150_MAGN_REG_REP_Z,
>>> +					  &tmp);
>>> +			if (ret < 0)
>>> +				return ret;
>>> +			*val = BMC150_MAGN_REGVAL_TO_REPZ(tmp);
>>> +			return IIO_VAL_INT;
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +}
>>> +
>>> +static int bmc150_magn_write_raw(struct iio_dev *indio_dev,
>>> +				 struct iio_chan_spec const *chan,
>>> +				 int val, int val2, long mask)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	switch (mask) {
>>> +	case IIO_CHAN_INFO_SAMP_FREQ:
>>> +		mutex_lock(&data->mutex);
>>> +		ret = bmc150_magn_set_odr(data, val);
>>> +		mutex_unlock(&data->mutex);
>>> +		return ret;
>>> +	case IIO_CHAN_INFO_CALIBREPETITIONS:
>>> +		switch (chan->channel2) {
>>> +		case IIO_MOD_X:
>>> +		case IIO_MOD_Y:
>>> +			if (val < 1 || val > 511)
>>> +				return -EINVAL;
>>> +			return regmap_update_bits(data->regmap,
>>> +						  BMC150_MAGN_REG_REP_XY,
>>> +						  0xFF,
>>> +						  BMC150_MAGN_REPXY_TO_REGVAL
>>> +						  (val));
>>> +		case IIO_MOD_Z:
>>> +			if (val < 1 || val > 256)
>>> +				return -EINVAL;
>>> +			return regmap_update_bits(data->regmap,
>>> +						  BMC150_MAGN_REG_REP_Z,
>>> +						  0xFF,
>>> +						  BMC150_MAGN_REPZ_TO_REGVAL
>>> +						  (val));
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +}
>>> +
>>> +static int bmc150_magn_validate_trigger(struct iio_dev *indio_dev,
>>> +					struct iio_trigger *trig)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	if (data->dready_trig != trig)
>>> +		return -EINVAL;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_update_scan_mode(struct iio_dev *indio_dev,
>>> +					const unsigned long *scan_mask)
>>> +{
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	kfree(data->buffer);
>>> +	data->buffer = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
>> Call be cynical, but how large can this buffer get?
>>
>> I'd just allocate it as part of data in the first place then you
>> can drop this function entirely and don't have to clean it up
>> separately.
> With all channels enabled it is 24 bytes. I'll allocate it with data.
> 
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	if (!data->buffer)
>>> +		return -ENOMEM;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("2 6 8 10 15 20 25 30");
>>> +
>>> +static struct attribute *bmc150_magn_attributes[] = {
>>> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
>>> +	NULL,
>>> +};
>>> +
>>> +static const struct attribute_group bmc150_magn_attrs_group = {
>>> +	.attrs = bmc150_magn_attributes,
>>> +};
>>> +
>>> +#define BMC150_MAGN_CHANNEL(_axis) {					\
>>> +	.type = IIO_MAGN,						\
>>> +	.modified = 1,							\
>>> +	.channel2 = IIO_MOD_##_axis,					\
>>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
>>> +			      BIT(IIO_CHAN_INFO_CALIBREPETITIONS),	\
>>> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) |	\
>>> +				    BIT(IIO_CHAN_INFO_SCALE),		\
>>> +	.scan_index = AXIS_##_axis,					\
>>> +	.scan_type = {							\
>>> +		.sign = 's',						\
>>> +		.realbits = 32,						\
>>> +		.storagebits = 32,					\
>>> +		.shift = 0,						\
>>> +		.endianness = IIO_LE					\
>>> +	},								\
>>> +}
>>> +
>>> +static const struct iio_chan_spec bmc150_magn_channels[] = {
>>> +	BMC150_MAGN_CHANNEL(X),
>>> +	BMC150_MAGN_CHANNEL(Y),
>>> +	BMC150_MAGN_CHANNEL(Z),
>>> +	IIO_CHAN_SOFT_TIMESTAMP(3),
>>> +};
>>> +
>>> +static const struct iio_info bmc150_magn_info = {
>>> +	.attrs = &bmc150_magn_attrs_group,
>>> +	.read_raw = bmc150_magn_read_raw,
>>> +	.write_raw = bmc150_magn_write_raw,
>>> +	.validate_trigger = bmc150_magn_validate_trigger,
>>> +	.update_scan_mode = bmc150_magn_update_scan_mode,
>>> +	.driver_module = THIS_MODULE,
>>> +};
>>> +
>>> +static const unsigned long bmc150_magn_scan_masks[] = {0x07, 0};
>>> +
>>> +static irqreturn_t bmc150_magn_trigger_handler(int irq, void *p)
>>> +{
>>> +	struct iio_poll_func *pf = p;
>>> +	struct iio_dev *indio_dev = pf->indio_dev;
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_read_xyz(data, data->buffer);
>>> +	mutex_unlock(&data->mutex);
>>> +	if (ret < 0)
>>> +		goto err;
>>> +
>>> +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
>>> +					   pf->timestamp);
>>> +
>>> +err:
>>> +	iio_trigger_notify_done(data->dready_trig);
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +static int bmc150_magn_init(struct bmc150_magn_data *data)
>>> +{
>>> +	int ret, chip_id;
>>> +	struct bmc150_magn_preset preset;
>>> +	struct bmc150_magn_trim_regs tregs;
>>> +
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND,
>>> +					 false);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev,
>>> +			"Failed to bring up device from suspend mode\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	ret = regmap_read(data->regmap, BMC150_MAGN_REG_CHIP_ID, &chip_id);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed reading chip id\n");
>>> +		goto err_poweroff;
>>> +	}
>>> +	if (chip_id != BMC150_MAGN_CHIP_ID_VAL) {
>>> +		dev_err(&data->client->dev, "Invalid chip id 0x%x\n", ret);
>>> +		ret = -ENODEV;
>>> +		goto err_poweroff;
>>> +	}
>>> +	dev_dbg(&data->client->dev, "Chip id %x\n", ret);
>>> +
>>> +	preset = bmc150_magn_presets_table[BMC150_MAGN_DEFAULT_PRESET];
>>> +	ret = bmc150_magn_set_odr(data, preset.odr);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to set ODR to %d\n",
>>> +			preset.odr);
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	ret = regmap_update_bits(data->regmap,
>>> +				 BMC150_MAGN_REG_REP_XY,
>>> +				 0xFF,
>>> +				 BMC150_MAGN_REPXY_TO_REGVAL(preset.rep_xy));
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to set REP XY to %d\n",
>>> +			preset.rep_xy);
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	ret = regmap_update_bits(data->regmap,
>>> +				 BMC150_MAGN_REG_REP_Z,
>>> +				 0xFF,
>> Umm. With a mask of 0xFF are we not just setting the whole register?  In which
>> case why use update_bits?   regmap_write instead...
> 
> I am using regmap_update_bits because it also checks if the value actually changed.
> I could use regmap_write here instead, since we are initializing the driver, but
> I would keep regmap_update_bits where the value is updated by the user (so we don't
> do the i2c transfer if the value did not change).
> 
>>> +				 BMC150_MAGN_REPZ_TO_REGVAL(preset.rep_z));
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to set REP Z to %d\n",
>>> +			preset.rep_z);
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	/* Cache trim registers in regmap. */
>> A little ugly. Is there no way of asking regmap to fill it's cache for certain registers?
>> Actually as I read it having taken a quick look, regcache_hw_init will read all your registers
>> given you haven't provided defaults.  Hence this will be cached already..
> Unfortunately it does not work in this case.
> In the current implementation the registers are not cached because num_reg_defaults_raw is not set.
> After setting num_reg_defaults_raw, regcache_hw_init will read all registers starting from register
> 0, but bmc150 magn starts its register map at register 0x40. I am not sure yet how to force a different
> stat register value or how to cache the registers in another way.
> 
> I will remove the regmap_bulk_read for now, so the actual transfer will be done when the first interrupt
> is handled. I will look further into this and come with a follow-up patch when I find a better solution.
Mark - any suggestions?
> 
>>> +	ret = regmap_bulk_read(data->regmap, BMC150_MAGN_REG_TRIM_START,
>>> +			       &tregs, sizeof(tregs));
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to read trim registers\n");
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
>>> +					 true);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "Failed to power on device\n");
>>> +		goto err_poweroff;
>>> +	}
>>> +
>>> +	return 0;
>>> +
>>> +err_poweroff:
>>> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_reset_intr(struct bmc150_magn_data *data)
>>> +{
>>> +	int tmp;
>>> +
>>> +	/*
>>> +	 * Data Ready (DRDY) is always cleared after
>>> +	 * readout of data registers ends.
>>> +	 */
>>> +	return regmap_read(data->regmap, BMC150_MAGN_REG_X_L, &tmp);
>> Good to see this here.  Often people don't bother on the basis
>> of course the driver has already read the data register!
>> (which it might not have done if the trigger is being used by another
>> device).
>>> +}
>>> +
>>> +static int bmc150_magn_trig_try_reen(struct iio_trigger *trig)
>>> +{
>>> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	if (!data->dready_trigger_on)
>>> +		return 0;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_reset_intr(data);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_data_rdy_trigger_set_state(struct iio_trigger *trig,
>>> +						  bool state)
>>> +{
>>> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret = 0;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	if (state == data->dready_trigger_on)
>>> +		goto err_unlock;
>>> +
>>> +	ret = bmc150_magn_set_power_state(data, state);
>>> +	if (ret < 0)
>>> +		goto err_unlock;
>>> +
>>> +	ret = regmap_update_bits(data->regmap, BMC150_MAGN_REG_INT_DRDY,
>>> +				 BMC150_MAGN_MASK_DRDY_EN,
>>> +				 state << BMC150_MAGN_SHIFT_DRDY_EN);
>>> +	if (ret < 0)
>>> +		goto err_poweroff;
>>> +
>>> +	data->dready_trigger_on = state;
>>> +
>>> +	if (state) {
>>> +		ret = bmc150_magn_reset_intr(data);
>>> +		if (ret < 0)
>>> +			goto err_poweroff;
>>> +	}
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return 0;
>>> +
>>> +err_poweroff:
>>> +	bmc150_magn_set_power_state(data, false);
>>> +err_unlock:
>>> +	mutex_unlock(&data->mutex);
>>> +	return ret;
>>> +}
>>> +
>>> +static const struct iio_trigger_ops bmc150_magn_trigger_ops = {
>>> +	.set_trigger_state = bmc150_magn_data_rdy_trigger_set_state,
>>> +	.try_reenable = bmc150_magn_trig_try_reen,
>>> +	.owner = THIS_MODULE,
>>> +};
>>> +
>>> +static int bmc150_magn_gpio_probe(struct i2c_client *client)
>>> +{
>>> +	struct device *dev;
>>> +	struct gpio_desc *gpio;
>>> +	int ret;
>>> +
>>> +	if (!client)
>>> +		return -EINVAL;
>>> +
>>> +	dev = &client->dev;
>>> +
>>> +	/* data ready GPIO interrupt pin */
>>> +	gpio = devm_gpiod_get_index(dev, BMC150_MAGN_GPIO_INT, 0);
>>> +	if (IS_ERR(gpio)) {
>>> +		dev_err(dev, "ACPI GPIO get index failed\n");
>>> +		return PTR_ERR(gpio);
>>> +	}
>>> +
>>> +	ret = gpiod_direction_input(gpio);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = gpiod_to_irq(gpio);
>>> +
>>> +	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static const char *bmc150_magn_match_acpi_device(struct device *dev)
>>> +{
>>> +	const struct acpi_device_id *id;
>>> +
>>> +	id = acpi_match_device(dev->driver->acpi_match_table, dev);
>>> +	if (!id)
>>> +		return NULL;
>>> +
>>> +	return dev_name(dev);
>>> +}
>>> +
>>> +static int bmc150_magn_probe(struct i2c_client *client,
>>> +			     const struct i2c_device_id *id)
>>> +{
>>> +	struct bmc150_magn_data *data;
>>> +	struct iio_dev *indio_dev;
>>> +	const char *name = NULL;
>>> +	int ret;
>>> +
>>> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>>> +	if (!indio_dev)
>>> +		return -ENOMEM;
>>> +
>>> +	data = iio_priv(indio_dev);
>>> +	i2c_set_clientdata(client, indio_dev);
>>> +	data->client = client;
>>> +
>>> +	if (id)
>>> +		name = id->name;
>>> +	else if (ACPI_HANDLE(&client->dev))
>>> +		name = bmc150_magn_match_acpi_device(&client->dev);
>>> +	else
>>> +		return -ENOSYS;
>>> +
>>> +	mutex_init(&data->mutex);
>>> +	data->regmap = devm_regmap_init_i2c(client, &bmc150_magn_regmap_config);
>>> +	if (IS_ERR(data->regmap)) {
>>> +		dev_err(&client->dev, "Failed to allocate register map\n");
>>> +		return PTR_ERR(data->regmap);
>>> +	}
>>> +
>>> +	ret = bmc150_magn_init(data);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	indio_dev->dev.parent = &client->dev;
>>> +	indio_dev->channels = bmc150_magn_channels;
>>> +	indio_dev->num_channels = ARRAY_SIZE(bmc150_magn_channels);
>>> +	indio_dev->available_scan_masks = bmc150_magn_scan_masks;
>>> +	indio_dev->name = name;
>>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>>> +	indio_dev->info = &bmc150_magn_info;
>>> +
>>> +	if (client->irq <= 0)
>>> +		client->irq = bmc150_magn_gpio_probe(client);
>>> +
>>> +	if (client->irq > 0) {
>>> +		data->dready_trig = devm_iio_trigger_alloc(&client->dev,
>>> +							   "%s-dev%d",
>>> +							   indio_dev->name,
>>> +							   indio_dev->id);
>>> +		if (!data->dready_trig) {
>>> +			ret = -ENOMEM;
>>> +			dev_err(&client->dev, "iio trigger alloc failed\n");
>>> +			goto err_poweroff;
>>> +		}
>>> +
>>> +		data->dready_trig->dev.parent = &client->dev;
>>> +		data->dready_trig->ops = &bmc150_magn_trigger_ops;
>>> +		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
>>> +		ret = iio_trigger_register(data->dready_trig);
>>> +		if (ret) {
>>> +			dev_err(&client->dev, "iio trigger register failed\n");
>>> +			goto err_poweroff;
>>> +		}
>>> +
>>> +		ret = iio_triggered_buffer_setup(indio_dev,
>>> +						 &iio_pollfunc_store_time,
>>> +						 bmc150_magn_trigger_handler,
>>> +						 NULL);
>>> +		if (ret < 0) {
>>> +			dev_err(&client->dev,
>>> +				"iio triggered buffer setup failed\n");
>>> +			goto err_trigger_unregister;
>>> +		}
>>> +
>>> +		ret = devm_request_threaded_irq(&client->dev, client->irq,
>>> +					     iio_trigger_generic_data_rdy_poll,
>>> +					     NULL,
>>> +					     IRQF_TRIGGER_RISING | IRQF_ONESHOT,
>>> +					     BMC150_MAGN_IRQ_NAME,
>>> +					     data->dready_trig);
>>> +		if (ret < 0) {
>>> +			dev_err(&client->dev, "request irq %d failed\n",
>>> +				client->irq);
>>> +			goto err_buffer_cleanup;
>>> +		}
>>> +	}
>>> +
>>> +	ret = iio_device_register(indio_dev);
>>> +	if (ret < 0) {
>>> +		dev_err(&client->dev, "unable to register iio device\n");
>>> +		goto err_buffer_cleanup;
>>> +	}
>>> +
>>> +	ret = pm_runtime_set_active(&client->dev);
>>> +	if (ret)
>>> +		goto err_iio_unregister;
>>> +
>>> +	pm_runtime_enable(&client->dev);
>>> +	pm_runtime_set_autosuspend_delay(&client->dev,
>>> +					 BMC150_MAGN_AUTO_SUSPEND_DELAY_MS);
>>> +	pm_runtime_use_autosuspend(&client->dev);
>>> +
>>> +	dev_dbg(&indio_dev->dev, "Registered device %s\n", name);
>>> +
>>> +	return 0;
>>> +
>>> +err_iio_unregister:
>>> +	iio_device_unregister(indio_dev);
>>> +err_buffer_cleanup:
>>
>> Hmm. There is an issue with this being obviously correct.
>> The unwind ordering different from setup.
>> Because you have devm_request_threaded_irq calls they will unwind only after these
>> calls, but should occur before.
>> Now it probaby makes no difference, but it does fail the obviously correct test.
>>
>> It's also the case in the remove.  I'd be inclined not to use the devm versin
>> of the irq request, but do it explicitly. This one comes up a lot and much like
>> the devm_iio_register_device call it's only really a good idea if everything
>> is managed.  In mixed cases, I'd avoid it.
>>
> I agree. I will use request_threaded_irq instead.
> 
>> Maybe I'm just being overly fussy...
>>
>>> +	if (data->dready_trig)
>>> +		iio_triggered_buffer_cleanup(indio_dev);
>>> +err_trigger_unregister:
>>> +	if (data->dready_trig)
>>> +		iio_trigger_unregister(data->dready_trig);
>>> +err_poweroff:
>>> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_remove(struct i2c_client *client)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	pm_runtime_disable(&client->dev);
>>> +	pm_runtime_set_suspended(&client->dev);
>>> +	pm_runtime_put_noidle(&client->dev);
>>> +
>>> +	iio_device_unregister(indio_dev);
>>> +
>>> +	if (data->dready_trig) {
>>> +		iio_triggered_buffer_cleanup(indio_dev);
>>> +		iio_trigger_unregister(data->dready_trig);
>>> +	}
>> As mentioned above, this clean up isn't needed if you simply
>> always make data->buffer the largest size it can ever be.
> Yes, I will remove this after allocating the data->buffer with data.
>>> +	kfree(data->buffer);
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +#ifdef CONFIG_PM
>>> +static int bmc150_magn_runtime_suspend(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
>>> +					 true);
>>> +	mutex_unlock(&data->mutex);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "powering off device failed\n");
>>> +		return -EAGAIN;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int bmc150_magn_runtime_resume(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +
>>> +	return bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
>>> +					  true);
>>> +}
>>> +#endif
>>> +
>>> +#ifdef CONFIG_PM_SLEEP
>>> +static int bmc150_magn_suspend(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SLEEP,
>>> +					 true);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int bmc150_magn_resume(struct device *dev)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
>>> +	struct bmc150_magn_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_NORMAL,
>>> +					 true);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +#endif
>>> +
>>> +static const struct dev_pm_ops bmc150_magn_pm_ops = {
>>> +	SET_SYSTEM_SLEEP_PM_OPS(bmc150_magn_suspend, bmc150_magn_resume)
>>> +	SET_RUNTIME_PM_OPS(bmc150_magn_runtime_suspend,
>>> +			   bmc150_magn_runtime_resume, NULL)
>>> +};
>>> +
>>> +static const struct acpi_device_id bmc150_magn_acpi_match[] = {
>>> +	{"BMC150B", 0},
>>> +	{},
>>> +};
>> nitpick, no blank line here. Tends to directly associate the structure
>> with the following macro which is visually nice..
> Sure, I will remove all blank lines you mentioned.
>>> +
>>> +MODULE_DEVICE_TABLE(acpi, bmc150_magn_acpi_match);
>>> +
>>> +static const struct i2c_device_id bmc150_magn_id[] = {
>>> +	{"bmc150_magn", 0},
>>> +	{},
>>> +};
>> Nitpick, no blank line.
>>> +
>>> +MODULE_DEVICE_TABLE(i2c, bmc150_magn_id);
>>> +
>>> +static struct i2c_driver bmc150_magn_driver = {
>>> +	.driver = {
>>> +		   .name = BMC150_MAGN_DRV_NAME,
>>> +		   .acpi_match_table = ACPI_PTR(bmc150_magn_acpi_match),
>>> +		   .pm = &bmc150_magn_pm_ops,
>>> +		   },
>>> +	.probe = bmc150_magn_probe,
>>> +	.remove = bmc150_magn_remove,
>>> +	.id_table = bmc150_magn_id,
>>> +};
>> Nitpick. I'd not bother with the blank line here.
>>> +
>>> +module_i2c_driver(bmc150_magn_driver);
>>> +
>>> +MODULE_AUTHOR("Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>");
>>> +MODULE_LICENSE("GPL v2");
>>> +MODULE_DESCRIPTION("BMC150 magnetometer driver");
>>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

[PATCH 3/3] iio: magn: bmc150_magn: Add devicetree binding documentation

[Irina Tirdea]

Add binding documentation for Bosch BMC150 magnetometer.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
---
 .../bindings/iio/magnetometer/bmc150_magn.txt        | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt b/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
new file mode 100644
index 0000000..4ed035c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
@@ -0,0 +1,20 @@
+* Bosch BMC150 magnetometer sensor
+
+http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf
+
+Required properties:
+
+  - compatible : should be "bosch,bmc150_magn"
+  - reg : the I2C address of the magnetometer
+
+Optional properties:
+
+  - gpios : should be device tree identifier of the magnetometer DRDY pin
+
+Example:
+
+bmc150_magn@12 {
+        compatible = "bosch,bmc150_magn";
+        reg = <0x12>;
+        interrupt-gpio = <&gpio1 0 1>;
+};
-- 
1.9.1

Re: [PATCH 3/3] iio: magn: bmc150_magn: Add devicetree binding documentation

[Jonathan Cameron]

On 17/04/15 11:50, Irina Tirdea wrote:
> Add binding documentation for Bosch BMC150 magnetometer.
> 
> Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
>  .../bindings/iio/magnetometer/bmc150_magn.txt        | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt b/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> new file mode 100644
> index 0000000..4ed035c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> @@ -0,0 +1,20 @@
> +* Bosch BMC150 magnetometer sensor
> +
> +http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf
> +
> +Required properties:
> +
> +  - compatible : should be "bosch,bmc150_magn"
> +  - reg : the I2C address of the magnetometer
> +
> +Optional properties:
> +
> +  - gpios : should be device tree identifier of the magnetometer DRDY pin
Hmm. Under device tree this should be done as an interrupt.  You only
(currently) need the dubious frig with gpios for ACPI I think.
> +
> +Example:
> +
> +bmc150_magn@12 {
> +        compatible = "bosch,bmc150_magn";
> +        reg = <0x12>;
> +        interrupt-gpio = <&gpio1 0 1>;
> +};
> 

RE: [PATCH 3/3] iio: magn: bmc150_magn: Add devicetree binding documentation

[Tirdea, Irina]

> -----Original Message-----
> From: linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org] On Behalf Of Jonathan Cameron
> Sent: 18 April, 2015 21:09
> To: Tirdea, Irina; linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Hartmut Knaack; Lars-Peter Clausen; Peter Meerwald; Rob Herring; Pawel Moll; Mark Rutland; Ian
> Campbell; Kumar Gala
> Subject: Re: [PATCH 3/3] iio: magn: bmc150_magn: Add devicetree binding documentation
> 
> On 17/04/15 11:50, Irina Tirdea wrote:
> > Add binding documentation for Bosch BMC150 magnetometer.
> >
> > Signed-off-by: Irina Tirdea <irina.tirdea-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> > ---
> >  .../bindings/iio/magnetometer/bmc150_magn.txt        | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> >
> > diff --git a/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> b/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> > new file mode 100644
> > index 0000000..4ed035c
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/iio/magnetometer/bmc150_magn.txt
> > @@ -0,0 +1,20 @@
> > +* Bosch BMC150 magnetometer sensor
> > +
> > +http://ae-bst.resource.bosch.com/media/products/dokumente/bmc150/BST-BMC150-DS000-04.pdf
> > +
> > +Required properties:
> > +
> > +  - compatible : should be "bosch,bmc150_magn"
> > +  - reg : the I2C address of the magnetometer
> > +
> > +Optional properties:
> > +
> > +  - gpios : should be device tree identifier of the magnetometer DRDY pin
> Hmm. Under device tree this should be done as an interrupt.  You only
> (currently) need the dubious frig with gpios for ACPI I think.
Using the gpios declared like this, it will go the same code path as the ACPI.
I wasn't sure which to list in the optional properties, so I used gpios because the other magnetometer device tree
bindings listed also gpios.

It is better to specify the interrupt directly since it will be handled by the core, so I will remove gpios and list interrupts
instead.

Thanks,
Irina

> > +
> > +Example:
> > +
> > +bmc150_magn@12 {
> > +        compatible = "bosch,bmc150_magn";
> > +        reg = <0x12>;
> > +        interrupt-gpio = <&gpio1 0 1>;
> > +};
> >
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html