[PATCH v5 0/4] iio: accel: adxl345: add calibration offset and sampling frequency support

[PATCH v5 0/4] iio: accel: adxl345: add calibration offset and sampling frequency support

[Akinobu Mita]

This patchset adds calibration offset and sampling frequency support for
adxl345 driver with some preparatory changes.

* v5 (Suggested by Andy Shevchenko)
- Introduce constant for nHZ per HZ
- Find an register setting without looping over all available frequencies
- Allow all user supplied values and round to an available frequency

* v4 (Suggested by Jonathan Cameron)
- Stop abusing scan_index and keep using address field in iio_chan_spec

* v3 (Suggested by Andy Shevchenko)
- Define ADXL345_REG_DATA_AXIS(si) for cleaner register access
- Define ADXL345_REG_OSF_AXIS(si) for cleaner register access
- Calculate sampling frequency at runtime instead of having constant table

* v2
- Adjust the value for the calibbias to make the same scale as the _raw
  measurement, and remove misused calibscale.

Akinobu Mita (4):
  iio: accel: adxl345: add link to datasheet
  iio: accel: adxl345: convert address field usage in iio_chan_spec
  iio: accel: adxl345: add calibration offset support
  iio: accel: adxl345: add sampling frequency support

 drivers/iio/accel/adxl345_core.c | 121 +++++++++++++++++++++++++++++++++++----
 1 file changed, 110 insertions(+), 11 deletions(-)

Cc: Eva Rachel Retuya <eraretuya@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
-- 
2.7.4

[PATCH v5 1/4] iio: accel: adxl345: add link to datasheet

[Akinobu Mita]

Add a link to the ADXL345 datasheet

Cc: Eva Rachel Retuya <eraretuya@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* v5
- No changes from v4

 drivers/iio/accel/adxl345_core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index 7251d0e..8e0d56b 100644
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -6,6 +6,8 @@
  * This file is subject to the terms and conditions of version 2 of
  * the GNU General Public License. See the file COPYING in the main
  * directory of this archive for more details.
+ *
+ * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL345.pdf
  */
 
 #include <linux/module.h>
-- 
2.7.4

[PATCH v5 2/4] iio: accel: adxl345: convert address field usage in iio_chan_spec

[Akinobu Mita]

Currently the address field in iio_chan_spec is filled with an accel
data register address for the corresponding axis.

In preparation for adding calibration offset support, this sets the
address field to the index of accel data registers instead of the actual
register address.

This change makes it easier to access both accel registers and
calibration offset registers with fewer lines of code as these are
located in X-axis, Y-axis, Z-axis order.

Cc: Eva Rachel Retuya <eraretuya@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* v5
- No changes from v4

 drivers/iio/accel/adxl345_core.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index 8e0d56b..7a25840 100644
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -23,6 +23,8 @@
 #define ADXL345_REG_DATAX0		0x32
 #define ADXL345_REG_DATAY0		0x34
 #define ADXL345_REG_DATAZ0		0x36
+#define ADXL345_REG_DATA_AXIS(index)	\
+	(ADXL345_REG_DATAX0 + (index) * sizeof(__le16))
 
 #define ADXL345_POWER_CTL_MEASURE	BIT(3)
 #define ADXL345_POWER_CTL_STANDBY	0x00
@@ -49,19 +51,19 @@ struct adxl345_data {
 	u8 data_range;
 };
 
-#define ADXL345_CHANNEL(reg, axis) {					\
+#define ADXL345_CHANNEL(index, axis) {					\
 	.type = IIO_ACCEL,						\
 	.modified = 1,							\
 	.channel2 = IIO_MOD_##axis,					\
-	.address = reg,							\
+	.address = index,						\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
 }
 
 static const struct iio_chan_spec adxl345_channels[] = {
-	ADXL345_CHANNEL(ADXL345_REG_DATAX0, X),
-	ADXL345_CHANNEL(ADXL345_REG_DATAY0, Y),
-	ADXL345_CHANNEL(ADXL345_REG_DATAZ0, Z),
+	ADXL345_CHANNEL(0, X),
+	ADXL345_CHANNEL(1, Y),
+	ADXL345_CHANNEL(2, Z),
 };
 
 static int adxl345_read_raw(struct iio_dev *indio_dev,
@@ -69,7 +71,7 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 			    int *val, int *val2, long mask)
 {
 	struct adxl345_data *data = iio_priv(indio_dev);
-	__le16 regval;
+	__le16 accel;
 	int ret;
 
 	switch (mask) {
@@ -79,12 +81,13 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 		 * ADXL345_REG_DATA(X0/Y0/Z0) contain the least significant byte
 		 * and ADXL345_REG_DATA(X0/Y0/Z0) + 1 the most significant byte
 		 */
-		ret = regmap_bulk_read(data->regmap, chan->address, &regval,
-				       sizeof(regval));
+		ret = regmap_bulk_read(data->regmap,
+				       ADXL345_REG_DATA_AXIS(chan->address),
+				       &accel, sizeof(accel));
 		if (ret < 0)
 			return ret;
 
-		*val = sign_extend32(le16_to_cpu(regval), 12);
+		*val = sign_extend32(le16_to_cpu(accel), 12);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = 0;
-- 
2.7.4

[PATCH v5 3/4] iio: accel: adxl345: add calibration offset support

[Akinobu Mita]

The ADXL345 provides the offset adjustment registers for each axis.
This adds the iio channel information for the calibraion offsets with
that feature.

Cc: Eva Rachel Retuya <eraretuya@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* v5
- No changes from v4

 drivers/iio/accel/adxl345_core.c | 41 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index 7a25840..7b29ae8 100644
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -18,6 +18,10 @@
 #include "adxl345.h"
 
 #define ADXL345_REG_DEVID		0x00
+#define ADXL345_REG_OFSX		0x1e
+#define ADXL345_REG_OFSY		0x1f
+#define ADXL345_REG_OFSZ		0x20
+#define ADXL345_REG_OFS_AXIS(index)	(ADXL345_REG_OFSX + (index))
 #define ADXL345_REG_POWER_CTL		0x2D
 #define ADXL345_REG_DATA_FORMAT		0x31
 #define ADXL345_REG_DATAX0		0x32
@@ -56,7 +60,8 @@ struct adxl345_data {
 	.modified = 1,							\
 	.channel2 = IIO_MOD_##axis,					\
 	.address = index,						\
-	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
+		BIT(IIO_CHAN_INFO_CALIBBIAS),				\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
 }
 
@@ -72,6 +77,7 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 {
 	struct adxl345_data *data = iio_priv(indio_dev);
 	__le16 accel;
+	unsigned int regval;
 	int ret;
 
 	switch (mask) {
@@ -94,6 +100,38 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 		*val2 = adxl345_uscale;
 
 		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		ret = regmap_read(data->regmap,
+				  ADXL345_REG_OFS_AXIS(chan->address), &regval);
+		if (ret < 0)
+			return ret;
+		/*
+		 * 8-bit resolution at +/- 2g, that is 4x accel data scale
+		 * factor
+		 */
+		*val = sign_extend32(regval, 7) * 4;
+
+		return IIO_VAL_INT;
+	}
+
+	return -EINVAL;
+}
+
+static int adxl345_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	struct adxl345_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBBIAS:
+		/*
+		 * 8-bit resolution at +/- 2g, that is 4x accel data scale
+		 * factor
+		 */
+		return regmap_write(data->regmap,
+				    ADXL345_REG_OFS_AXIS(chan->address),
+				    val / 4);
 	}
 
 	return -EINVAL;
@@ -101,6 +139,7 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 
 static const struct iio_info adxl345_info = {
 	.read_raw	= adxl345_read_raw,
+	.write_raw	= adxl345_write_raw,
 };
 
 int adxl345_core_probe(struct device *dev, struct regmap *regmap,
-- 
2.7.4

[PATCH v5 4/4] iio: accel: adxl345: add sampling frequency support

[Akinobu Mita]

The ADXL345 provides selectable output data rate.  This adds the iio
channel information for the sampling frequency with that feature.

Cc: Eva Rachel Retuya <eraretuya@gmail.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
* v5 (Suggested by Andy Shevchenko)
- Introduce constant for nHZ per HZ
- Find an register setting without looping over all available frequencies
- Allow all user supplied values and round to an available frequency

 drivers/iio/accel/adxl345_core.c | 57 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
index 7b29ae8..fba1ae2 100644
--- a/drivers/iio/accel/adxl345_core.c
+++ b/drivers/iio/accel/adxl345_core.c
@@ -14,6 +14,7 @@
 #include <linux/regmap.h>
 
 #include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
 
 #include "adxl345.h"
 
@@ -22,6 +23,7 @@
 #define ADXL345_REG_OFSY		0x1f
 #define ADXL345_REG_OFSZ		0x20
 #define ADXL345_REG_OFS_AXIS(index)	(ADXL345_REG_OFSX + (index))
+#define ADXL345_REG_BW_RATE		0x2C
 #define ADXL345_REG_POWER_CTL		0x2D
 #define ADXL345_REG_DATA_FORMAT		0x31
 #define ADXL345_REG_DATAX0		0x32
@@ -30,6 +32,10 @@
 #define ADXL345_REG_DATA_AXIS(index)	\
 	(ADXL345_REG_DATAX0 + (index) * sizeof(__le16))
 
+#define ADXL345_BW_RATE			GENMASK(3, 0)
+#define ADXL345_BASE_RATE_NANO_HZ	97656250LL
+#define NHZ_PER_HZ			1000000000LL
+
 #define ADXL345_POWER_CTL_MEASURE	BIT(3)
 #define ADXL345_POWER_CTL_STANDBY	0x00
 
@@ -62,7 +68,8 @@ struct adxl345_data {
 	.address = index,						\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |			\
 		BIT(IIO_CHAN_INFO_CALIBBIAS),				\
-	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |		\
+		BIT(IIO_CHAN_INFO_SAMP_FREQ),				\
 }
 
 static const struct iio_chan_spec adxl345_channels[] = {
@@ -77,6 +84,7 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 {
 	struct adxl345_data *data = iio_priv(indio_dev);
 	__le16 accel;
+	long long samp_freq_nhz;
 	unsigned int regval;
 	int ret;
 
@@ -112,6 +120,16 @@ static int adxl345_read_raw(struct iio_dev *indio_dev,
 		*val = sign_extend32(regval, 7) * 4;
 
 		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = regmap_read(data->regmap, ADXL345_REG_BW_RATE, &regval);
+		if (ret < 0)
+			return ret;
+
+		samp_freq_nhz = ADXL345_BASE_RATE_NANO_HZ <<
+				(regval & ADXL345_BW_RATE);
+		*val = div_s64_rem(samp_freq_nhz, NHZ_PER_HZ, val2);
+
+		return IIO_VAL_INT_PLUS_NANO;
 	}
 
 	return -EINVAL;
@@ -122,6 +140,7 @@ static int adxl345_write_raw(struct iio_dev *indio_dev,
 			    int val, int val2, long mask)
 {
 	struct adxl345_data *data = iio_priv(indio_dev);
+	s64 n;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_CALIBBIAS:
@@ -132,14 +151,50 @@ static int adxl345_write_raw(struct iio_dev *indio_dev,
 		return regmap_write(data->regmap,
 				    ADXL345_REG_OFS_AXIS(chan->address),
 				    val / 4);
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		n = div_s64(val * NHZ_PER_HZ + val2, ADXL345_BASE_RATE_NANO_HZ);
+		n = ilog2(max_t(s64, n, 1));
+
+		return regmap_update_bits(data->regmap, ADXL345_REG_BW_RATE,
+					  ADXL345_BW_RATE,
+					  min_t(int, n, ADXL345_BW_RATE));
 	}
 
 	return -EINVAL;
 }
 
+static int adxl345_write_raw_get_fmt(struct iio_dev *indio_dev,
+				     struct iio_chan_spec const *chan,
+				     long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
+"0.09765625 0.1953125 0.390625 0.78125 1.5625 3.125 6.25 12.5 25 50 100 200 400 800 1600 3200"
+);
+
+static struct attribute *adxl345_attrs[] = {
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group adxl345_attrs_group = {
+	.attrs = adxl345_attrs,
+};
+
 static const struct iio_info adxl345_info = {
+	.attrs		= &adxl345_attrs_group,
 	.read_raw	= adxl345_read_raw,
 	.write_raw	= adxl345_write_raw,
+	.write_raw_get_fmt	= adxl345_write_raw_get_fmt,
 };
 
 int adxl345_core_probe(struct device *dev, struct regmap *regmap,
-- 
2.7.4

Re: [PATCH v5 4/4] iio: accel: adxl345: add sampling frequency support

[Andy Shevchenko]

On Sat, Jun 30, 2018 at 7:32 PM, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> The ADXL345 provides selectable output data rate.  This adds the iio
> channel information for the sampling frequency with that feature.

> +       case IIO_CHAN_INFO_SAMP_FREQ:
> +               n = div_s64(val * NHZ_PER_HZ + val2, ADXL345_BASE_RATE_NANO_HZ);

> +               n = ilog2(max_t(s64, n, 1));

(1)

> +
> +               return regmap_update_bits(data->regmap, ADXL345_REG_BW_RATE,
> +                                         ADXL345_BW_RATE,

> +                                         min_t(int, n, ADXL345_BW_RATE));

(2)

Yes, looks pretty much good!
Though, bit manipulations would be sligtly shorter

Instead of (1) and (2) just do

clamp_t(ilog2(n), 0, ..._RATE)

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 0/4] iio: accel: adxl345: add calibration offset and sampling frequency support

[Andy Shevchenko]

On Sat, Jun 30, 2018 at 7:32 PM, Akinobu Mita <akinobu.mita@gmail.com> wrote:
> This patchset adds calibration offset and sampling frequency support for
> adxl345 driver with some preparatory changes.
>

One small comment to patch 5, otherwise FWIW,

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> * v5 (Suggested by Andy Shevchenko)
> - Introduce constant for nHZ per HZ
> - Find an register setting without looping over all available frequencies
> - Allow all user supplied values and round to an available frequency
>
> * v4 (Suggested by Jonathan Cameron)
> - Stop abusing scan_index and keep using address field in iio_chan_spec
>
> * v3 (Suggested by Andy Shevchenko)
> - Define ADXL345_REG_DATA_AXIS(si) for cleaner register access
> - Define ADXL345_REG_OSF_AXIS(si) for cleaner register access
> - Calculate sampling frequency at runtime instead of having constant table
>
> * v2
> - Adjust the value for the calibbias to make the same scale as the _raw
>   measurement, and remove misused calibscale.
>
> Akinobu Mita (4):
>   iio: accel: adxl345: add link to datasheet
>   iio: accel: adxl345: convert address field usage in iio_chan_spec
>   iio: accel: adxl345: add calibration offset support
>   iio: accel: adxl345: add sampling frequency support
>
>  drivers/iio/accel/adxl345_core.c | 121 +++++++++++++++++++++++++++++++++++----
>  1 file changed, 110 insertions(+), 11 deletions(-)
>
> Cc: Eva Rachel Retuya <eraretuya@gmail.com>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Jonathan Cameron <jic23@kernel.org>
> --
> 2.7.4
>



-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 4/4] iio: accel: adxl345: add sampling frequency support

[Akinobu Mita]

2018=E5=B9=B47=E6=9C=885=E6=97=A5(=E6=9C=A8) 7:06 Andy Shevchenko <andy.she=
vchenko@gmail.com>:
>
> On Sat, Jun 30, 2018 at 7:32 PM, Akinobu Mita <akinobu.mita@gmail.com> wr=
ote:
> > The ADXL345 provides selectable output data rate.  This adds the iio
> > channel information for the sampling frequency with that feature.
>
> > +       case IIO_CHAN_INFO_SAMP_FREQ:
> > +               n =3D div_s64(val * NHZ_PER_HZ + val2, ADXL345_BASE_RAT=
E_NANO_HZ);
>
> > +               n =3D ilog2(max_t(s64, n, 1));
>
> (1)
>
> > +
> > +               return regmap_update_bits(data->regmap, ADXL345_REG_BW_=
RATE,
> > +                                         ADXL345_BW_RATE,
>
> > +                                         min_t(int, n, ADXL345_BW_RATE=
));
>
> (2)
>
> Yes, looks pretty much good!
> Though, bit manipulations would be sligtly shorter
>
> Instead of (1) and (2) just do
>
> clamp_t(ilog2(n), 0, ..._RATE)

Sounds good.  I'll use clamp_val() instead of clamp_t().

        n =3D clamp_val(ilog2(n), 0, ADXL345_BW_RATE);

Re: [PATCH v5 4/4] iio: accel: adxl345: add sampling frequency support

[Andy Shevchenko]

On Fri, Jul 6, 2018 at 7:08 PM, Akinobu Mita <akinobu.mita@gmail.com> wrote=
:
> 2018=E5=B9=B47=E6=9C=885=E6=97=A5(=E6=9C=A8) 7:06 Andy Shevchenko <andy.s=
hevchenko@gmail.com>:

> Sounds good.  I'll use clamp_val() instead of clamp_t().
>
>         n =3D clamp_val(ilog2(n), 0, ADXL345_BW_RATE);

Yup! But put it directly to the call instead of min_t(). No need to
assign n again (and it would mislead the n meanning).

--=20
With Best Regards,
Andy Shevchenko

Re: [PATCH v5 1/4] iio: accel: adxl345: add link to datasheet

[Jonathan Cameron]

On Sun,  1 Jul 2018 01:32:42 +0900
Akinobu Mita <akinobu.mita@gmail.com> wrote:

> Add a link to the ADXL345 datasheet
> 
> Cc: Eva Rachel Retuya <eraretuya@gmail.com>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Jonathan Cameron <jic23@kernel.org>
> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

I already applied the first few of these, no need to
send them again whilst we work on patch 4 onwards!

It doesn't really matter though as I can pick up parts
of a series just fine anyway.

Thanks,

Jonathan

> ---
> * v5
> - No changes from v4
> 
>  drivers/iio/accel/adxl345_core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iio/accel/adxl345_core.c b/drivers/iio/accel/adxl345_core.c
> index 7251d0e..8e0d56b 100644
> --- a/drivers/iio/accel/adxl345_core.c
> +++ b/drivers/iio/accel/adxl345_core.c
> @@ -6,6 +6,8 @@
>   * This file is subject to the terms and conditions of version 2 of
>   * the GNU General Public License. See the file COPYING in the main
>   * directory of this archive for more details.
> + *
> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL345.pdf
>   */
>  
>  #include <linux/module.h>