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Date: Fri, 2 Jul 2010 14:22:20 +0530
From: "Datta, Shubhrajyoti" <shubhrajyoti@...com>
To: Jonathan Cameron <jic23@....ac.uk>
CC: "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
"sfking@...dc.com" <sfking@...dc.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [RFC] [PATCH] digital compass hmc5843
> -----Original Message-----
> From: Jonathan Cameron [mailto:jic23@....ac.uk]
> Sent: Thursday, July 01, 2010 9:29 PM
> To: Datta, Shubhrajyoti
> Cc: linux-iio@...r.kernel.org; sfking@...dc.com; linux-
> kernel@...r.kernel.org
> Subject: Re: [RFC] [PATCH] digital compass hmc5843
>
> On 07/01/10 16:12, Datta, Shubhrajyoti wrote:
> > Adding support for the Honeywell HMC5843. The interface to the device is
> i2c.
> > - Comments added
> > - The interface name of sampling frequency made similar to the
> convention
> > - The sysfs entries changed to io device
> I'm still getting spaces rather than tabs... My guess is your email
> client is still eating tabs.
>
> Few more coments below. It still needs a bit blugeoning to meet the abi.
> We have to be strict or we will have nasty issues with userspace code
> finding incompatibilities between devices.
>
> Also, please document the non standard attributes under iio/Documentation
> as per the current abi docs.
>
> Thanks,
>
> Jonathan
> >
> > Signed-off-by: Shubhrajyoti D <shubhrajyoti@...com>
> > ---
> > drivers/staging/iio/Kconfig | 1 +
> > drivers/staging/iio/Makefile | 1 +
> > drivers/staging/iio/magnetometer/Kconfig | 15 +
> > drivers/staging/iio/magnetometer/Makefile | 5 +
> > drivers/staging/iio/magnetometer/hmc5843.c | 607
> ++++++++++++++++++++++++++++
> > 5 files changed, 629 insertions(+), 0 deletions(-)
> > create mode 100644 drivers/staging/iio/magnetometer/Kconfig
> > create mode 100644 drivers/staging/iio/magnetometer/Makefile
> > create mode 100644 drivers/staging/iio/magnetometer/hmc5843.c
> >
> > diff --git a/drivers/staging/iio/Kconfig b/drivers/staging/iio/Kconfig
> > index b0e6244..569b938 100644
> > --- a/drivers/staging/iio/Kconfig
> > +++ b/drivers/staging/iio/Kconfig
> > @@ -44,6 +44,7 @@ source "drivers/staging/iio/adc/Kconfig"
> > source "drivers/staging/iio/gyro/Kconfig"
> > source "drivers/staging/iio/imu/Kconfig"
> > source "drivers/staging/iio/light/Kconfig"
> > +source "drivers/staging/iio/magnetometer/Kconfig"
> >
> > source "drivers/staging/iio/trigger/Kconfig"
> >
> > diff --git a/drivers/staging/iio/Makefile b/drivers/staging/iio/Makefile
> > index 3502b39..10d1f6b 100644
> > --- a/drivers/staging/iio/Makefile
> > +++ b/drivers/staging/iio/Makefile
> > @@ -14,5 +14,6 @@ obj-y += adc/
> > obj-y += gyro/
> > obj-y += imu/
> > obj-y += light/
> > +obj-y += magnetometer/
> >
> > obj-y += trigger/
> > \ No newline at end of file
> > diff --git a/drivers/staging/iio/magnetometer/Kconfig
> b/drivers/staging/iio/magnetometer/Kconfig
> > new file mode 100644
> > index 0000000..6c67981
> > --- /dev/null
> > +++ b/drivers/staging/iio/magnetometer/Kconfig
> > @@ -0,0 +1,15 @@
> > +#
> > +# Magnetometer sensors
> > +#
> > +comment "Magnetometer sensors"
> > +
> > +config SENSORS_HMC5843
> > + tristate "Honeywell HMC5843 3-Axis Magnetometer"
> > + depends on I2C
> > + help
> > + Say Y here to add support for the Honeywell HMC 5843 3-Axis
> > + Magnetometer (digital compass).
> > +
> > + To compile this driver as a module, choose M here: the module
> > + will be called hmc5843
> > +
> > diff --git a/drivers/staging/iio/magnetometer/Makefile
> b/drivers/staging/iio/magnetometer/Makefile
> > new file mode 100644
> > index 0000000..f9bfb2e
> > --- /dev/null
> > +++ b/drivers/staging/iio/magnetometer/Makefile
> > @@ -0,0 +1,5 @@
> > +#
> > +# Makefile for industrial I/O Magnetometer sensors
> > +#
> > +
> > +obj-$(CONFIG_SENSORS_HMC5843) += hmc5843.o
> > diff --git a/drivers/staging/iio/magnetometer/hmc5843.c
> b/drivers/staging/iio/magnetometer/hmc5843.c
> > new file mode 100644
> > index 0000000..d741d39
> > --- /dev/null
> > +++ b/drivers/staging/iio/magnetometer/hmc5843.c
> > @@ -0,0 +1,607 @@
> > +/* Copyright (c) 2010 Shubhrajyoti Datta <shubhrajyoti@...com>
> > +
> > + This program is free software; you can redistribute it and/or
> modify
> > + it under the terms of the GNU General Public License as published
> by
> > + the Free Software Foundation; either version 2 of the License, or
> > + (at your option) any later version.
> > +
> > + This program is distributed in the hope that 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.
> > +
> > + You should have received a copy of the GNU General Public License
> > + along with this program; if not, write to the Free Software
> > + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > +*/
> > +
> > +#include <linux/module.h>
> > +#include <linux/init.h>
> > +#include <linux/i2c.h>
> > +#include <linux/slab.h>
> > +#include <linux/types.h>
> > +#include "../iio.h"
> > +#include "../sysfs.h"
> > +#include "magnet.h"
> > +
> > +#define HMC5843_I2C_ADDRESS 0x1E
> > +
> > +#define HMC5843_CONFIG_REG_A 0x00
> > +#define HMC5843_CONFIG_REG_B 0x01
> > +#define HMC5843_MODE_REG 0x02
> > +#define HMC5843_DATA_OUT_X_MSB_REG 0x03
> > +#define HMC5843_DATA_OUT_X_LSB_REG 0x04
> > +#define HMC5843_DATA_OUT_Y_MSB_REG 0x05
> > +#define HMC5843_DATA_OUT_Y_LSB_REG 0x06
> > +#define HMC5843_DATA_OUT_Z_MSB_REG 0x07
> > +#define HMC5843_DATA_OUT_Z_LSB_REG 0x08
> > +#define HMC5843_STATUS_REG 0x09
> > +#define HMC5843_ID_REG_A 0x0A
> > +#define HMC5843_ID_REG_B 0x0B
> > +#define HMC5843_ID_REG_C 0x0C
> > +
> > +#define HMC5843_ID_REG_LENGTH 0x03
> > +#define HMC5843_ID_STRING "H43"
> > +
> > +/*
> > + * Range settings in (+-)Ga
> > + * */
> > +#define RANGE_GAIN_OFFSET 0x05
> > +
> > +#define RANGE_0_7 0x00
> > +#define RANGE_1_0 0x01 /* default
> */
> > +#define RANGE_1_5 0x02
> > +#define RANGE_2_0 0x03
> > +#define RANGE_3_2 0x04
> > +#define RANGE_3_8 0x05
> > +#define RANGE_4_5 0x06
> > +#define RANGE_6_5 0x07 /* Not
> recommended */
> > +
> > +/*
> > + * Device status
> > + */
> > +#define DATA_READY 0x01
> > +#define DATA_OUTPUT_LOCK 0x02
> > +#define VOLTAGE_REGULATOR_ENABLED 0x04
> > +
> > +/*
> > + * Mode register configuration
> > + */
> > +#define MODE_CONVERSION_CONTINUOUS 0x00
> > +#define MODE_CONVERSION_SINGLE 0x01
> > +#define MODE_IDLE 0x02
> > +#define MODE_SLEEP 0x03
> > +
> > +/* Minimum Data Output Rate in 1/10 Hz */
> > +#define RATE_OFFSET 0x02
> > +#define RATE_BITMASK 0x1C
> > +#define RATE_5 0x00
> > +#define RATE_10 0x01
> > +#define RATE_20 0x02
> > +#define RATE_50 0x03
> > +#define RATE_100 0x04
> > +#define RATE_200 0x05
> > +#define RATE_500 0x06
> > +#define RATE_NOT_USED 0x07
> > +
> > +/*
> > + * Device Configutration
> > + */
> > +#define CONF_NORMAL 0x00
> > +#define CONF_POSITIVE_BIAS 0x01
> > +#define CONF_NEGATIVE_BIAS 0x02
> > +#define CONF_NOT_USED 0x03
> > +#define MEAS_CONF_MASK 0x03
> > +
> > +static const int regval_to_counts_per_mg[] = {
> > + 1620,
> > + 1300,
> > + 970,
> > + 780,
> > + 530,
> > + 460,
> > + 390,
> > + 280
> > +};
> > +static const int regval_to_input_field_mg[] = {
> > + 700,
> > + 1000,
> > + 1500,
> > + 2000,
> > + 3200,
> > + 3800,
> > + 4500,
> > + 6500
> > +};
> > +static const int samp_freq_to_regval[] = {
> > + 5,
> > + 10,
> > + 20,
> > + 50,
> > + 100,
> > + 200,
> > + 500,
> > +};
> > +
> > +/* Addresses to scan: 0x1E */
> > +static const unsigned short normal_i2c[] = { HMC5843_I2C_ADDRESS,
> > + I2C_CLIENT_END
> };
> > +
> > +/* Each client has this additional data */
> > +struct hmc5843_data {
> > + struct iio_dev *indio_dev;
> > + u8 rate;
> > + u8 meas_conf;
> > + u8 operating_mode;
> > + u8 range;
> > +};
> > +
> This is not needed. init_client is only called after it is defined.
Will change it.
> > +static void hmc5843_init_client(struct i2c_client *client);
> > +
> > +static s32 hmc5843_configure(struct i2c_client *client,
> > + u8 operating_mode)
> > +{
> > + /* The lower two bits contain the current conversion mode */
> > + return i2c_smbus_write_byte_data(client,
> > + HMC5843_MODE_REG,
> > + (operating_mode & 0x03));
> > +}
> > +
> > +/* Return the measurement value from the specified channel */
> > +
> Nitpick: bonus blank line. Have the comment immediately above
Agree
> the function it referring to...
> > +static ssize_t hmc5843_read_measurement(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + s16 coordinate_val;
> > + struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
> > + s32 result;
> > +
> > + result = i2c_smbus_read_byte_data(client, HMC5843_STATUS_REG);
> > + while (!(result & DATA_READY))
> > + result = i2c_smbus_read_byte_data(client,
> HMC5843_STATUS_REG);
> > +
> > + result = i2c_smbus_read_word_data(client, this_attr->address);
> > + if (result < 0)
> > + return -EINVAL;
> > +
> > + coordinate_val = (s16)swab16((u16)result);
> > + return sprintf(buf, "%d\n", coordinate_val);
> > +}
> > +static IIO_DEV_ATTR_MAGN_X(hmc5843_read_measurement,
> > + HMC5843_DATA_OUT_X_MSB_REG);
> > +static IIO_DEV_ATTR_MAGN_Y(hmc5843_read_measurement,
> > + HMC5843_DATA_OUT_Y_MSB_REG);
> > +static IIO_DEV_ATTR_MAGN_Z(hmc5843_read_measurement,
> > + HMC5843_DATA_OUT_Z_MSB_REG);
> Good to see the docs. If possible can you do a file for
> staging/iio/Documentation
> so these are available to people without having to dive in the source
> code.
Will take an action item to add documentation.
> I would imaging this functionality is going to interact strangely with
> the read attributes seeing as I assume they will fail if the device
> is asleep?
Yes still thought of not imposing any policy from the driver and give a handle.
> > +/*
> > + * From the datasheet
> > + * 0 - Continuous-Conversion Mode: In continuous-conversion mode, the
> > + * device continuously performs conversions an places the result in the
> > + * data register.
> > + *
> > + * 1 - Single-Conversion Mode : device performs a single measurement,
> > + * sets RDY high and returned to sleep mode
> > + *
> > + * 2 - Idle Mode : Device is placed in idle mode.
> > + *
> > + * 3 - Sleep Mode. Device is placed in sleep mode.
> > + *
> > + */
> > +static ssize_t hmc5843_show_operating_mode(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + return sprintf(buf, "%d\n", data->operating_mode);
> > +}
> New line please.
Agree
> > +static ssize_t hmc5843_set_operating_mode(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf,
> > + size_t count)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
> > + unsigned long operating_mode = 0;
> > + s32 status;
> > + int error;
> > + error = strict_strtoul(buf, 10, &operating_mode);
> > + if (error)
> > + return error;
> > + dev_dbg(dev, "set Conversion mode to %lu\n", operating_mode);
> > + if (operating_mode > MODE_SLEEP)
> > + return -EINVAL;
> > +
> > + status = i2c_smbus_write_byte_data(client, this_attr->address,
> > + operating_mode);
> > + if (status)
> > + return -EINVAL;
> > +
> > + data->operating_mode = operating_mode;
> > + return count;
> > +}
> > +static IIO_DEVICE_ATTR(operating_mode,
> > + S_IWUSR | S_IRUGO,
> > + hmc5843_show_operating_mode,
> > + hmc5843_set_operating_mode,
> > + HMC5843_MODE_REG);
> new line please
Agree
> > +/*
> > + * API for setting the measurement configuration to
> > + * Normal, Positive bias and Negitive bias
> > + * From the datasheet
> > + *
> > + * Normal measurement configuration (default): In normal measurement
> > + * configuration the device follows normal measurement flow. Pins BP
> and BN
> > + * are left floating and high impedance.
> > + *
> > + * Positive bias configuration: In positive bias configuration, a
> positive
> > + * current is forced across the resistive load on pins BP and BN.
> > + *
> > + * Negative bias configuration. In negative bias configuration, a
> negative
> > + * current is forced across the resistive load on pins BP and BN.
> > + *
> > + */
> Ah, so the resulting change in the device is dependent on what BP and BN
> are wired up to. Thanks for the clarification. Again, if this can go
> in a seperate documentation file that would be great.
> > +static s32 hmc5843_set_meas_conf(struct i2c_client *client,
> > + u8 meas_conf)
> > +{
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + u8 reg_val;
> > + reg_val = (meas_conf & MEAS_CONF_MASK) | (data->rate <<
> RATE_OFFSET);
> > + return i2c_smbus_write_byte_data(client, HMC5843_CONFIG_REG_A,
> reg_val);
> > +}
> > +
> > +static ssize_t hmc5843_show_measurement_configuration(struct device
> *dev,
> > + struct device_attribute
> *attr,
> > + char *buf)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + return sprintf(buf, "%d\n", data->meas_conf);
> > +}
> > +
> > +static ssize_t hmc5843_set_measurement_configuration(struct device
> *dev,
> > + struct device_attribute
> *attr,
> > + const char *buf,
> > + size_t count)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + unsigned long meas_conf = 0;
> > +
> > + int error = strict_strtoul(buf, 10, &meas_conf);
> > + if (error)
> > + return error;
> > + dev_dbg(dev, "set mode to %lu\n", meas_conf);
> > + if (hmc5843_set_meas_conf(client, meas_conf))
> > + return -EINVAL;
> > + data->meas_conf = meas_conf;
> > + return count;
> > +}
> > +static IIO_DEVICE_ATTR(meas_conf,
> > + S_IWUSR | S_IRUGO,
> > + hmc5843_show_measurement_configuration,
> > + hmc5843_set_measurement_configuration,
> > + 0);
> New line
> > +/*
> > + * From Datasheet
> > + * The table shows the minimum data output
> > + * Value | Minimum data output rate(Hz)
> > + * 0 | 0.5
> > + * 1 | 1
> > + * 2 | 2
> > + * 3 | 5
> > + * 4 | 10 (default)
> > + * 5 | 20
> > + * 6 | 50
> > + * 7 | Not used
> > + */
> Thanks for chaning this, but the abi does specifiy units....
> > +static ssize_t show_avail_samp_freq(struct device *dev,
> > + struct device_attribute *attr, char *buf)
> > +{
> > + char freq[] = {"5 , 10, 20, 50, 100, 200 ,500"};
> > + return sprintf(buf, "In units of 1/10 hz: %s\n", freq);
> Gah. This has to be machine readable or no userspace program
> is ever going to be able to use it. So a simple list. The abi
> specifies the units (Hz).
> > +}
> The IIO_CONST_ATTR macro makes this easy. There is even a convenient
> macro for this case.
I think that having a Hz as units will have its own issues. First the decimal implementation. However I am open to the implementation.
Also do you know of a driver that takes care of this.
>
> static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("0.5 1 2 5 10 20 50");
>
>
> Then strncmp with the options to set the value up. The rounding approach
> gets tricky with a non integer value so probably easier to only allow
> these
> values.
Allowing only this value will result in default/ reject case and will keep the previous value, may confuse the application
>
> > +static IIO_DEV_ATTR_AVAIL_SAMP_FREQ(show_avail_samp_freq);
> > +
> > +static s32 hmc5843_set_rate(struct i2c_client *client,
> > + u8 rate)
> > +{
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + u8 reg_val;
> > +
> > + reg_val = (data->meas_conf) | (rate << RATE_OFFSET);
> > + if (rate >= RATE_NOT_USED) {
> > + dev_err(&client->dev,
> > + "This data output rate is not supported \n");
> > + return -EINVAL;
> > + }
> > + return i2c_smbus_write_byte_data(client, HMC5843_CONFIG_REG_A,
> reg_val);
> > +}
> > +
> > +static ssize_t set_sampling_frequency(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > +
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + unsigned long rate = 0;
> > + unsigned long reg_val;
> > + int error;
> > +
> > + error = strict_strtoul(buf, 10, &rate);
> > + if (error)
> > + return error;
> > + if (rate < 10)
> > + reg_val = RATE_5;
> > + else if (rate < 20)
> > + reg_val = RATE_10;
> > + else if (rate < 50)
> > + reg_val = RATE_20;
> > + else if (rate < 100)
> > + reg_val = RATE_50;
> > + else if (rate < 200)
> > + reg_val = RATE_100;
> > + else if (rate < 500)
> > + reg_val = RATE_200;
> > + else
> > + reg_val = RATE_500;
> > +
> > + dev_dbg(dev, "set rate to %lu\n", reg_val);
> > + if (hmc5843_set_rate(client, reg_val) == -EINVAL)
> > + return -EINVAL;
> > + data->rate = rate;
> > + return count;
> > +}
> > +
> > +static ssize_t show_sampling_frequency(struct device *dev,
> > + struct device_attribute *attr, char *buf)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
> > + u32 rate;
> > +
> > + rate = i2c_smbus_read_byte_data(client, this_attr->address);
> > + if (rate < 0)
> > + return -EINVAL;
> > + rate = (rate & RATE_BITMASK) >> RATE_OFFSET;
> This also becomes a query into a string array to allow that 0.5 value.
> > + return sprintf(buf, "%d\n", samp_freq_to_regval[rate]);
> > +}
> > +static IIO_DEVICE_ATTR(sampling_frequency,
> > + S_IWUSR | S_IRUGO,
> > + show_sampling_frequency,
> > + set_sampling_frequency,
> > + HMC5843_CONFIG_REG_A);
>
> It isn't always helpful to just have documentation like this in the
> kernel code. Please add an abi description to staging/iio/Documentation/
>
> Also, if at all possible, can get this to conform to equivalent of
> in0_scale (see the sysfs-class-iio file). Abi says that magn parameters
> are to be converted to Gauss (maybe we should make that milli-gauss?)
>
I would like to see milli units as we generally take the hwmon approach and most of the units there are milli.
> Thus we need an additional attribute saying what is available.
>
> static IIO_CONST_ATTR(magn_scale_available, "0.000000617284 0.00000076923
> <others> 0.00000357143");
> The numbers correspond to A where value_in_gauss=A*raw_reading + B/
>
> We then match against these exact values (or go for nearest) on the
> gain_store
> and output the relevant value on gain_show.
>
> Although these values correspond directly to table 12 in the datasheet,
> I'm
> a little confused by this table. Perhaps you can clarify?
>
> Take the top line, Maximum value is 2047 counts. So if we have 1620
> counts/ milli gauss
> then this equals a couple of milli gauss not 0.7 gauss?
My understanding is that the range and gain are trade off between the range of the field it is sensitive to and the granularity of the reported values.
> > +/*
> > + * From Datasheet
> > + * Nominal gain settings
> > + * Value | Sensor Input Field Range(Ga) | Gain(counts/ milli-
> gauss)
> > + *0 |(+-)0.7 |1620
> > + *1 |(+-)1.0 |1300
> > + *2 |(+-)1.5 |970
> > + *3 |(+-)2.0 |780
> > + *4 |(+-)3.2 |530
> > + *5 |(+-)3.8 |460
> > + *6 |(+-)4.5 |390
> > + *7 |(+-)6.5 |280
> > + */
> > +static ssize_t show_range(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + u8 range;
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > +
> > + range = data->range;
> No units please. That just makes things tricky for userspace whilst
> giving no
> additional information as the ABI specifies the allowed units. You also
> encourage
> people to apply units to the values they write to these attributes.
> > + return sprintf(buf, " %dmGa\n",
> regval_to_input_field_mg[range]);
> > +}
> > +
> > +static ssize_t set_range(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf,
> > + size_t count)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + unsigned long range = 0;
> > + int error;
> > +
> > + error = strict_strtoul(buf, 10, &range);
> > + if (error)
> > + return error;
> > + dev_dbg(dev, "set range to %lu\n", range);
> > +
> > + if (range > RANGE_6_5)
> > + return -EINVAL;
> > +
> > + data->range = range;
> > + range = range << RANGE_GAIN_OFFSET;
> > + if (i2c_smbus_write_byte_data(client, this_attr->address, range)
> ==
> > +
> -EINVAL)
> > + return -EINVAL;
> > +
> > + return count;
> > +}
> > +
> > +static IIO_DEVICE_ATTR(magn_range,
> > + S_IWUSR | S_IRUGO,
> > + show_range,
> > + set_range,
> > + HMC5843_CONFIG_REG_B);
> > +
> > +static ssize_t show_gain(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct iio_dev *indio_dev = dev_get_drvdata(dev);
> > + struct i2c_client *client = to_i2c_client(indio_dev-
> >dev.parent);
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + return sprintf(buf, "%d\n", regval_to_counts_per_mg[data-
> >range]);
> > +}
> > +static IIO_DEVICE_ATTR(magn_gain, S_IRUGO, show_gain, NULL , 0);
> > +
> > +
> > +static struct attribute *hmc5843_attributes[] = {
> > + &iio_dev_attr_meas_conf.dev_attr.attr,
> > + &iio_dev_attr_operating_mode.dev_attr.attr,
> > + &iio_dev_attr_sampling_frequency.dev_attr.attr,
> > + &iio_dev_attr_magn_range.dev_attr.attr,
> > + &iio_dev_attr_magn_gain.dev_attr.attr,
> > + &iio_dev_attr_magn_x_raw.dev_attr.attr,
> > + &iio_dev_attr_magn_y_raw.dev_attr.attr,
> > + &iio_dev_attr_magn_z_raw.dev_attr.attr,
> > + &iio_dev_attr_available_sampling_frequency.dev_attr.attr,
> > + NULL
> > +};
> > +
> > +static const struct attribute_group hmc5843_group = {
> > + .attrs = hmc5843_attributes,
> > +};
> > +
> > +static int hmc5843_detect(struct i2c_client *client,
> > + struct i2c_board_info *info)
> > +{
> > + unsigned char id_str[HMC5843_ID_REG_LENGTH];
> > +
> > + if (client->addr != HMC5843_I2C_ADDRESS)
> > + return -ENODEV;
> > +
> > + if (i2c_smbus_read_i2c_block_data(client, HMC5843_ID_REG_A,
> > + HMC5843_ID_REG_LENGTH, id_str)
> > + != HMC5843_ID_REG_LENGTH)
> > + return -ENODEV;
> > +
> > + if (0 != strncmp(id_str, HMC5843_ID_STRING,
> HMC5843_ID_REG_LENGTH))
> > + return -ENODEV;
> > +
> > + return 0;
> > +}
> > +
> > +/* Called when we have found a new HMC5843. */
> > +static void hmc5843_init_client(struct i2c_client *client)
> > +{
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + hmc5843_set_meas_conf(client, data->meas_conf);
> > + hmc5843_set_rate(client, data->rate);
> > + hmc5843_configure(client, data->operating_mode);
> > + i2c_smbus_write_byte_data(client, HMC5843_CONFIG_REG_B, data-
> >range);
> > + pr_info("HMC5843 initialized\n");
> > +}
> > +
> > +static int hmc5843_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + struct hmc5843_data *data;
> > + int err = 0;
> > +
> > + data = kzalloc(sizeof(struct hmc5843_data), GFP_KERNEL);
> > + if (!data) {
> > + err = -ENOMEM;
> > + goto exit;
> > + }
> > +
> > + /* default settings at probe */
> > +
> > + data->meas_conf = CONF_NORMAL;
> > + data->range = RANGE_1_0;
> > + data->operating_mode = MODE_CONVERSION_CONTINUOUS;
> > +
> > + i2c_set_clientdata(client, data);
> > +
> > + /* Initialize the HMC5843 chip */
> > + hmc5843_init_client(client);
> > +
> > + data->indio_dev = iio_allocate_device();
> > + if (!data->indio_dev) {
> > + err = -ENOMEM;
> > + goto exit_free;
> > + }
> > + data->indio_dev->attrs = &hmc5843_group;
> > + data->indio_dev->dev.parent = &client->dev;
> > + data->indio_dev->dev_data = (void *)(data);
> > + data->indio_dev->driver_module = THIS_MODULE;
> > + data->indio_dev->modes = INDIO_DIRECT_MODE;
> > + err = iio_device_register(data->indio_dev);
> > + if (err)
> > + goto exit_free;
> > + return 0;
> > +exit_free:
> > + kfree(data);
> > +exit:
> > + return err;
> > +}
> > +
> > +static int hmc5843_remove(struct i2c_client *client)
> > +{
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + /* sleep mode to save power */
> > + hmc5843_configure(client, MODE_SLEEP);
> > + iio_device_unregister(data->indio_dev);
> > + sysfs_remove_group(&client->dev.kobj, &hmc5843_group);
> > + kfree(i2c_get_clientdata(client));
> > + return 0;
> > +}
> > +
> > +static int hmc5843_suspend(struct i2c_client *client, pm_message_t
> mesg)
> > +{
> > + hmc5843_configure(client, MODE_SLEEP);
> > + return 0;
> > +}
> > +
> > +static int hmc5843_resume(struct i2c_client *client)
> > +{
> > + struct hmc5843_data *data = i2c_get_clientdata(client);
> > + hmc5843_configure(client, data->operating_mode);
> > + return 0;
> > +}
> > +
> > +static const struct i2c_device_id hmc5843_id[] = {
> > + { "hmc5843", 0 },
> > + { }
> > +};
> > +
> > +static struct i2c_driver hmc5843_driver = {
> > + .driver = {
> > + .name = "hmc5843",
> > + },
> > + .id_table = hmc5843_id,
> > + .probe = hmc5843_probe,
> > + .remove = hmc5843_remove,
> > + .detect = hmc5843_detect,
> > + .address_list = normal_i2c,
> > + .suspend = hmc5843_suspend,
> > + .resume = hmc5843_resume,
> > +};
> > +
> > +static int __init hmc5843_init(void)
> > +{
> You still need to remove this pair of printks.
> > + printk(KERN_INFO "init!\n");
> > + return i2c_add_driver(&hmc5843_driver);
> > +}
> > +
> > +static void __exit hmc5843_exit(void)
> > +{
> > + printk(KERN_INFO "exit!\n");
> > + i2c_del_driver(&hmc5843_driver);
> > +}
> > +
> > +MODULE_AUTHOR("Shubhrajyoti Datta <shubhrajyoti@...com");
> > +MODULE_DESCRIPTION("HMC5843 driver");
> > +MODULE_LICENSE("GPL");
> > +
> > +module_init(hmc5843_init);
> > +module_exit(hmc5843_exit);
> > --
> > 1.5.4.7
> >
> > --
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> > the body of a message to majordomo@...r.kernel.org
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> >
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