Re: [PATCH v2 3/4] dt-bindings: hwmon: Add ti-max-expected-current-microamp property to ina2xx

2017-10-12 Thread Maciej Purski 



On 10/12/2017 03:55 PM, Guenter Roeck wrote:

On 10/12/2017 06:00 AM, Maciej Purski wrote:



On 10/12/2017 02:39 PM, Krzysztof Kozlowski wrote:

On Thu, Oct 12, 2017 at 2:36 PM, Maciej Purski <m.pur...@samsung.com> wrote:

Add optional max expected current property which allows calibrating
the ina sensor in order to achieve requested measure scale. Document
the changes in Documentation/hwmon/ina2xx.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
  Documentation/devicetree/bindings/hwmon/ina2xx.txt | 4 +++-
  Documentation/hwmon/ina2xx | 3 +++
  2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/ina2xx.txt 
b/Documentation/devicetree/bindings/hwmon/ina2xx.txt

index 02af0d9..49ef0be 100644
--- a/Documentation/devicetree/bindings/hwmon/ina2xx.txt
+++ b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
@@ -14,11 +14,13 @@ Optional properties:

  - shunt-resistor
 Shunt resistor value in micro-Ohm
-
+- ti-max-expected-current-microamp
+   Max expected current value in mA
  Example:

  ina220@44 {
 compatible = "ti,ina220";
 reg = <0x44>;
 shunt-resistor = <1000>;
+   ti-max-expected-current-microamp = <3000>;
  };
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index cfd31d9..30620e8 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -55,6 +55,9 @@ The shunt value in micro-ohms can be set via platform data 
or device tree at

  compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
  refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
  if the device tree is used.
+The max expected current value in miliamp can be set via platform data


mili or micro?

BR,
Krzysztof


Sorry, these should be mili everywhere. I'll fix this.



You sure ? I think DT usually uses micro.

Guenter


Yeah, you're right. I was intending to make it milli, but I haven't checked that
all DTS use micro. Sorry for confusion.

Best Regards,

Maciej






+or device tree at compile-time or via currX_max attribute in sysfs
+at run-time.

  Additionally ina226 supports update_interval attribute as described in
  Documentation/hwmon/sysfs-interface. Internally the interval is the sum of
--
2.7.4













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[PATCH v3 2/4] hwmon: (ina2xx) Make max expected current configurable

2017-10-12 Thread Maciej Purski 
Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet:
current_lsb = max_expected_current / 2^15
calibration_register = 0.00512 / (current_lsb * r_shunt)
power_lsb = 25 * current_lsb (for ina231, 230, 226)
power_lsb = 20 * current_lsb (for older ones)

Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model, but
users have no impact on the precision of the device.

Make max expected current configurable from device tree or platform_data.
Allow changing it from sysfs as currX_max attribute. Update calibration
register and power_lsb value on each currX_max change.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 drivers/hwmon/ina2xx.c | 107 +++--
 1 file changed, 95 insertions(+), 12 deletions(-)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 62e38fa..04648f6 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -80,6 +80,8 @@
 /* common attrs, ina226 attrs and NULL */
 #define INA2XX_MAX_ATTRIBUTE_GROUPS3
 
+#define INA2XX_MAX_EXPECTED_MA_DEFAULT  BIT(15)   /* current_lsb = 1 mA */
+
 /*
  * Both bus voltage and shunt voltage conversion times for ina226 are set
  * to 0b0100 on POR, which translates to 2200 microseconds in total.
@@ -100,13 +102,16 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
 };
 
 struct ina2xx_data {
const struct ina2xx_config *config;
 
-   long rshunt;
+   long rshunt;/* uOhms */
+   unsigned int max_expected_current;  /* mA */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
struct mutex config_lock;
struct regmap *regmap;
 
@@ -121,7 +126,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
},
[ina226] = {
.config_default = INA226_CONFIG_DEFAULT,
@@ -130,7 +135,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
-   .power_lsb = 25000,
+   .power_lsb_factor = 25,
},
 };
 
@@ -169,10 +174,17 @@ static u16 ina226_interval_to_reg(int interval)
return INA226_SHIFT_AVG(avg_bits);
 }
 
+/*
+ * Calculate calibration value according to equation 1 in ina226 datasheet
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ * Current LSB is in uA and RShunt is in uOhms, so in order to keep
+ * calibration value scaled RShunt must be converted to mOhms.
+ */
 static int ina2xx_calibrate(struct ina2xx_data *data)
 {
+   int r_shunt = DIV_ROUND_CLOSEST(data->rshunt, 1000);
u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
-   data->rshunt);
+   data->current_lsb * r_shunt);
 
return regmap_write(data->regmap, INA2XX_CALIBRATION, val);
 }
@@ -187,13 +199,29 @@ static int ina2xx_init(struct ina2xx_data *data)
if (ret < 0)
return ret;
 
-   /*
-* Set current LSB to 1mA, shunt is in uOhms
-* (equation 13 in datasheet).
-*/
return ina2xx_calibrate(data);
 }
 
+/*
+ * Set max_expected_current (mA) and calculate current_lsb (uA),
+ * according to equation 2 in ina226 datasheet. Power LSB is calculated
+ * by multiplying Current LSB by a given factor, which may vary depending
+ * on ina version.
+ */
+static int ina2xx_set_max_expected_current(struct ina2xx_data *data,
+  unsigned int val)
+{
+   if (val <= 0 || val > data->config->calibration_factor)
+   return -EINVAL;
+
+   data->max_expected_current = val;
+   data->current_lsb = DIV_ROUND_CLOSEST(data->max_expected_current * 1000,
+ 1 << 15);
+   data->power_lsb = data->current_lsb * data->config->power_lsb_factor;
+
+   return 0;
+}
+
 static int ina2xx_read_reg(struct device *dev, int reg, unsigned int *regval)
 {
struct ina2xx_data *data = dev_get_drvdata(dev);
@@ -268,11 +296,11 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 
reg,
val = DIV_ROUND_CLOSEST(val, 1000);
break;
case INA2XX_POWER:
-   val = regval * data->config->power_lsb;
+   val = regv

[PATCH v3 1/4] iio: adc: ina2xx: Make max expected current configurable

2017-10-12 Thread Maciej Purski 
Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet:
current_lsb = max_expected_current / 2^15
calibration_register = 0.00512 / (current_lsb * r_shunt)
power_lsb = 25 * current_lsb (for ina231, 230, 226)
power_lsb = 20 * current_lsb (for older ones)

Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model, but
users have no impact on the precision of the device.

Make max expected current configurable from device tree or platform_data.
Allow changing current_lsb from sysfs. It is exposed in sysfs as
scale attribute for IIO current channel. Update calibration register and
power_lsb value on each scale change.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 drivers/iio/adc/ina2xx-adc.c | 96 ++--
 include/linux/platform_data/ina2xx.h |  2 +
 2 files changed, 73 insertions(+), 25 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index a16f8c6..be26dfc 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -56,6 +56,7 @@
 #define INA226_DEFAULT_IT  1110
 
 #define INA2XX_RSHUNT_DEFAULT   1
+#define INA2XX_MAX_EXPECTED_MA_DEFAULT BIT(15) /* current_lsb = 1 mA */
 
 /*
  * bit masks for reading the settings in the configuration register
@@ -114,7 +115,7 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
enum ina2xx_ids chip_id;
 };
 
@@ -123,7 +124,9 @@ struct ina2xx_chip_info {
struct task_struct *task;
const struct ina2xx_config *config;
struct mutex state_lock;
-   unsigned int shunt_resistor;
+   unsigned int shunt_resistor;/* uOhms */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
int avg;
int int_time_vbus; /* Bus voltage integration time uS */
int int_time_vshunt; /* Shunt voltage integration time uS */
@@ -137,7 +140,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
.chip_id = ina219,
},
[ina226] = {
@@ -146,7 +149,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
-   .power_lsb = 25000,
+   .power_lsb_factor = 25,
.chip_id = ina226,
},
 };
@@ -210,14 +213,15 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 
case INA2XX_POWER:
/* processed (mW) = raw*lsb (uW) / 1000 */
-   *val = chip->config->power_lsb;
+   *val = chip->power_lsb;
*val2 = 1000;
return IIO_VAL_FRACTIONAL;
 
case INA2XX_CURRENT:
-   /* processed (mA) = raw (mA) */
-   *val = 1;
-   return IIO_VAL_INT;
+   /* processed (mA) = raw*lsb (uA) / 1000 */
+   *val = chip->current_lsb;
+   *val2 = 1000;
+   return IIO_VAL_FRACTIONAL;
}
}
 
@@ -353,6 +357,36 @@ static int ina219_set_int_time_vshunt(struct 
ina2xx_chip_info *chip,
return 0;
 }
 
+/*
+ * Calculate calibration value according to equation 1 in ina226 datasheet
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ * Current LSB is in uA and RShunt is in uOhms, so RShunt should be
+ * converted to mOhms in order to keep the scale.
+ * There is no need to expose the CALIBRATION register
+ * to the user for now. But we need to reset this register
+ * if the user updates RShunt or max expected current after driver
+ * init, e.g upon reading an EEPROM/Probe-type value.
+ */
+static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
+{
+   unsigned int rshunt = DIV_ROUND_CLOSEST(chip->shunt_resistor, 1000);
+   u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
+chip->current_lsb * rshunt);
+
+   return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
+}
+
+static int ina2xx_set_scale(struct ina2xx_chip_info *chip, unsigned int val)
+{
+   if (val <= 0 || val > chip->config->calibration_factor)
+   return -EINVAL;
+
+   chip->current_lsb = val;
+   chip->power_lsb = chip->current_ls

[PATCH v3 3/4] dt-bindings: hwmon: Add ti-max-expected-current-milliamp property to ina2xx

2017-10-12 Thread Maciej Purski 
Add optional max expected current property which allows calibrating
the ina sensor in order to achieve requested measure scale. Document
the changes in Documentation/hwmon/ina2xx.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 Documentation/devicetree/bindings/hwmon/ina2xx.txt | 4 +++-
 Documentation/hwmon/ina2xx | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/ina2xx.txt 
b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
index 02af0d9..9268595 100644
--- a/Documentation/devicetree/bindings/hwmon/ina2xx.txt
+++ b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
@@ -14,11 +14,13 @@ Optional properties:
 
 - shunt-resistor
Shunt resistor value in micro-Ohm
-
+- ti-max-expected-current-milliamp
+   Max expected current value in mA
 Example:
 
 ina220@44 {
compatible = "ti,ina220";
reg = <0x44>;
shunt-resistor = <1000>;
+   ti-max-expected-current-milliamp = <3000>;
 };
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index cfd31d9..30620e8 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -55,6 +55,9 @@ The shunt value in micro-ohms can be set via platform data or 
device tree at
 compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
 refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
 if the device tree is used.
+The max expected current value in miliamp can be set via platform data
+or device tree at compile-time or via currX_max attribute in sysfs
+at run-time.
 
 Additionally ina226 supports update_interval attribute as described in
 Documentation/hwmon/sysfs-interface. Internally the interval is the sum of
-- 
2.7.4

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[PATCH v3 4/4] ARM: dts: Add ti-max-expected-current-milliamp properties for ina231 in Odroid XU3

2017-10-12 Thread Maciej Purski 
Set max expected current to values required by the documentation,
in order to achieve desired precision.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 arch/arm/boot/dts/exynos5422-odroidxu3.dts | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/exynos5422-odroidxu3.dts 
b/arch/arm/boot/dts/exynos5422-odroidxu3.dts
index 9ed6564..a34c1e5 100644
--- a/arch/arm/boot/dts/exynos5422-odroidxu3.dts
+++ b/arch/arm/boot/dts/exynos5422-odroidxu3.dts
@@ -28,6 +28,7 @@
compatible = "ti,ina231";
reg = <0x40>;
shunt-resistor = <1>;
+   ti-max-expected-current-milliamp = <9000>;
};
 
/* memory: VDD_MEM */
@@ -35,6 +36,7 @@
compatible = "ti,ina231";
reg = <0x41>;
shunt-resistor = <1>;
+   ti-max-expected-current-milliamp = <3000>;
};
 
/* GPU: VDD_G3D */
@@ -42,6 +44,7 @@
compatible = "ti,ina231";
reg = <0x44>;
shunt-resistor = <1>;
+   ti-max-expected-current-milliamp = <5000>;
};
 
/* A7 cluster: VDD_KFC */
@@ -49,6 +52,7 @@
compatible = "ti,ina231";
reg = <0x45>;
shunt-resistor = <1>;
+   ti-max-expected-current-milliamp = <2000>;
};
 };
 
-- 
2.7.4

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[PATCH v3 0/4] Make max expected current configurable for ina2xx drivers

2017-10-12 Thread Maciej Purski 
Hi all,

this patchset makes it possible to calibrate ina2xx drivers with different
calibration values, which are calculated using max expected current value.
It can be read from device tree, platform data or changed during run-time
using sysfs. If it isn't specified in device tree or platform data, the
driver uses default value, thanks to which the behaviour of the driver
doesn't change in this case.

There are two drivers for ina2xx: hwmon and iio. Changes are made
for both of them and their bindings as well.

These changes allow setting sensor's precision to the required by the board.
It is useful in Odroid XU3. Therefore this patchset also sets
max-expected-current in OdroidXU3 device tree to values from documentation.

Best Regards,

Maciej Purski

---
Changes in v3:
- fix units inconsistency

Changes in v2:
- make scale attribute for current iio channel writable as instead of
  adding new attribute max_expected_current
- use currX_max standard attribute in hwmon instead of adding new
  attribute
- fix max expected current property name
- update commit messages

Maciej Purski (4):
  iio: adc: ina2xx: Make max expected current configurable
  hwmon: (ina2xx) Make max expected current configurable
  dt-bindings: hwmon: Add ti-max-expected-current-microamp property to
ina2xx
  ARM: dts: Add ti-max-expected-current-microamp properties for ina231
in Odroid XU3

 Documentation/devicetree/bindings/hwmon/ina2xx.txt |   4 +-
 Documentation/hwmon/ina2xx |   3 +
 arch/arm/boot/dts/exynos5422-odroidxu3.dts |   4 +
 drivers/hwmon/ina2xx.c | 106 ++---
 drivers/iio/adc/ina2xx-adc.c   |  97 ++-
 include/linux/platform_data/ina2xx.h   |   2 +
 6 files changed, 178 insertions(+), 38 deletions(-)

-- 
2.7.4

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Re: [PATCH v2 3/4] dt-bindings: hwmon: Add ti-max-expected-current-microamp property to ina2xx

2017-10-12 Thread Maciej Purski 



On 10/12/2017 02:39 PM, Krzysztof Kozlowski wrote:

On Thu, Oct 12, 2017 at 2:36 PM, Maciej Purski <m.pur...@samsung.com> wrote:

Add optional max expected current property which allows calibrating
the ina sensor in order to achieve requested measure scale. Document
the changes in Documentation/hwmon/ina2xx.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
  Documentation/devicetree/bindings/hwmon/ina2xx.txt | 4 +++-
  Documentation/hwmon/ina2xx | 3 +++
  2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/ina2xx.txt 
b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
index 02af0d9..49ef0be 100644
--- a/Documentation/devicetree/bindings/hwmon/ina2xx.txt
+++ b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
@@ -14,11 +14,13 @@ Optional properties:

  - shunt-resistor
 Shunt resistor value in micro-Ohm
-
+- ti-max-expected-current-microamp
+   Max expected current value in mA
  Example:

  ina220@44 {
 compatible = "ti,ina220";
 reg = <0x44>;
 shunt-resistor = <1000>;
+   ti-max-expected-current-microamp = <3000>;
  };
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index cfd31d9..30620e8 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -55,6 +55,9 @@ The shunt value in micro-ohms can be set via platform data or 
device tree at
  compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
  refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
  if the device tree is used.
+The max expected current value in miliamp can be set via platform data


mili or micro?

BR,
Krzysztof


Sorry, these should be mili everywhere. I'll fix this.




+or device tree at compile-time or via currX_max attribute in sysfs
+at run-time.

  Additionally ina226 supports update_interval attribute as described in
  Documentation/hwmon/sysfs-interface. Internally the interval is the sum of
--
2.7.4






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[PATCH v2 2/4] hwmon: (ina2xx) Make max expected current configurable

2017-10-12 Thread Maciej Purski 
Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet:
current_lsb = max_expected_current / 2^15
calibration_register = 0.00512 / (current_lsb * r_shunt)
power_lsb = 25 * current_lsb (for ina231, 230, 226)
power_lsb = 20 * current_lsb (for older ones)

Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model, but
users have no impact on the precision of the device.

Make max expected current configurable from device tree or platform_data.
Allow changing it from sysfs as currX_max attribute. Update calibration
register and power_lsb value on each currX_max change.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 drivers/hwmon/ina2xx.c | 107 +++--
 1 file changed, 95 insertions(+), 12 deletions(-)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 62e38fa..bcaf814 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -80,6 +80,8 @@
 /* common attrs, ina226 attrs and NULL */
 #define INA2XX_MAX_ATTRIBUTE_GROUPS3
 
+#define INA2XX_MAX_EXPECTED_MA_DEFAULT  BIT(15)   /* current_lsb = 1 mA */
+
 /*
  * Both bus voltage and shunt voltage conversion times for ina226 are set
  * to 0b0100 on POR, which translates to 2200 microseconds in total.
@@ -100,13 +102,16 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
 };
 
 struct ina2xx_data {
const struct ina2xx_config *config;
 
-   long rshunt;
+   long rshunt;/* uOhms */
+   unsigned int max_expected_current;  /* mA */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
struct mutex config_lock;
struct regmap *regmap;
 
@@ -121,7 +126,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
},
[ina226] = {
.config_default = INA226_CONFIG_DEFAULT,
@@ -130,7 +135,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
-   .power_lsb = 25000,
+   .power_lsb_factor = 25,
},
 };
 
@@ -169,10 +174,17 @@ static u16 ina226_interval_to_reg(int interval)
return INA226_SHIFT_AVG(avg_bits);
 }
 
+/*
+ * Calculate calibration value according to equation 1 in ina226 datasheet
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ * Current LSB is in uA and RShunt is in uOhms, so in order to keep
+ * calibration value scaled RShunt must be converted to mOhms.
+ */
 static int ina2xx_calibrate(struct ina2xx_data *data)
 {
+   int r_shunt = DIV_ROUND_CLOSEST(data->rshunt, 1000);
u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
-   data->rshunt);
+   data->current_lsb * r_shunt);
 
return regmap_write(data->regmap, INA2XX_CALIBRATION, val);
 }
@@ -187,13 +199,29 @@ static int ina2xx_init(struct ina2xx_data *data)
if (ret < 0)
return ret;
 
-   /*
-* Set current LSB to 1mA, shunt is in uOhms
-* (equation 13 in datasheet).
-*/
return ina2xx_calibrate(data);
 }
 
+/*
+ * Set max_expected_current (mA) and calculate current_lsb (uA),
+ * according to equation 2 in ina226 datasheet. Power LSB is calculated
+ * by multiplying Current LSB by a given factor, which may vary depending
+ * on ina version.
+ */
+static int ina2xx_set_max_expected_current(struct ina2xx_data *data,
+  unsigned int val)
+{
+   if (val <= 0 || val > data->config->calibration_factor)
+   return -EINVAL;
+
+   data->max_expected_current = val;
+   data->current_lsb = DIV_ROUND_CLOSEST(data->max_expected_current * 1000,
+ 1 << 15);
+   data->power_lsb = data->current_lsb * data->config->power_lsb_factor;
+
+   return 0;
+}
+
 static int ina2xx_read_reg(struct device *dev, int reg, unsigned int *regval)
 {
struct ina2xx_data *data = dev_get_drvdata(dev);
@@ -268,11 +296,11 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 
reg,
val = DIV_ROUND_CLOSEST(val, 1000);
break;
case INA2XX_POWER:
-   val = regval * data->config->power_lsb;
+   val = regv

[PATCH v2 3/4] dt-bindings: hwmon: Add ti-max-expected-current-microamp property to ina2xx

2017-10-12 Thread Maciej Purski 
Add optional max expected current property which allows calibrating
the ina sensor in order to achieve requested measure scale. Document
the changes in Documentation/hwmon/ina2xx.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 Documentation/devicetree/bindings/hwmon/ina2xx.txt | 4 +++-
 Documentation/hwmon/ina2xx | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/hwmon/ina2xx.txt 
b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
index 02af0d9..49ef0be 100644
--- a/Documentation/devicetree/bindings/hwmon/ina2xx.txt
+++ b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
@@ -14,11 +14,13 @@ Optional properties:
 
 - shunt-resistor
Shunt resistor value in micro-Ohm
-
+- ti-max-expected-current-microamp
+   Max expected current value in mA
 Example:
 
 ina220@44 {
compatible = "ti,ina220";
reg = <0x44>;
shunt-resistor = <1000>;
+   ti-max-expected-current-microamp = <3000>;
 };
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index cfd31d9..30620e8 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -55,6 +55,9 @@ The shunt value in micro-ohms can be set via platform data or 
device tree at
 compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
 refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
 if the device tree is used.
+The max expected current value in miliamp can be set via platform data
+or device tree at compile-time or via currX_max attribute in sysfs
+at run-time.
 
 Additionally ina226 supports update_interval attribute as described in
 Documentation/hwmon/sysfs-interface. Internally the interval is the sum of
-- 
2.7.4

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[PATCH v2 1/4] iio: adc: ina2xx: Make max expected current configurable

2017-10-12 Thread Maciej Purski 
Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet:
current_lsb = max_expected_current / 2^15
calibration_register = 0.00512 / (current_lsb * r_shunt)
power_lsb = 25 * current_lsb (for ina231, 230, 226)
power_lsb = 20 * current_lsb (for older ones)

Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model, but
users have no impact on the precision of the device.

Make max expected current configurable from device tree or platform_data.
Allow changing current_lsb from sysfs. It is exposed in sysfs as
scale attribute for IIO current channel. Update calibration register and
power_lsb value on each scale change.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 drivers/iio/adc/ina2xx-adc.c | 96 ++--
 include/linux/platform_data/ina2xx.h |  2 +
 2 files changed, 73 insertions(+), 25 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index a16f8c6..7f1ae79 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -56,6 +56,7 @@
 #define INA226_DEFAULT_IT  1110
 
 #define INA2XX_RSHUNT_DEFAULT   1
+#define INA2XX_MAX_EXPECTED_MA_DEFAULT BIT(15) /* current_lsb = 1 mA */
 
 /*
  * bit masks for reading the settings in the configuration register
@@ -114,7 +115,7 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
enum ina2xx_ids chip_id;
 };
 
@@ -123,7 +124,9 @@ struct ina2xx_chip_info {
struct task_struct *task;
const struct ina2xx_config *config;
struct mutex state_lock;
-   unsigned int shunt_resistor;
+   unsigned int shunt_resistor;/* uOhms */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
int avg;
int int_time_vbus; /* Bus voltage integration time uS */
int int_time_vshunt; /* Shunt voltage integration time uS */
@@ -137,7 +140,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
.chip_id = ina219,
},
[ina226] = {
@@ -146,7 +149,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
-   .power_lsb = 25000,
+   .power_lsb_factor = 25,
.chip_id = ina226,
},
 };
@@ -210,14 +213,15 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 
case INA2XX_POWER:
/* processed (mW) = raw*lsb (uW) / 1000 */
-   *val = chip->config->power_lsb;
+   *val = chip->power_lsb;
*val2 = 1000;
return IIO_VAL_FRACTIONAL;
 
case INA2XX_CURRENT:
-   /* processed (mA) = raw (mA) */
-   *val = 1;
-   return IIO_VAL_INT;
+   /* processed (mA) = raw*lsb (uA) / 1000 */
+   *val = chip->current_lsb;
+   *val2 = 1000;
+   return IIO_VAL_FRACTIONAL;
}
}
 
@@ -353,6 +357,36 @@ static int ina219_set_int_time_vshunt(struct 
ina2xx_chip_info *chip,
return 0;
 }
 
+/*
+ * Calculate calibration value according to equation 1 in ina226 datasheet
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ * Current LSB is in uA and RShunt is in uOhms, so RShunt should be
+ * converted to mOhms in order to keep the scale.
+ * There is no need to expose the CALIBRATION register
+ * to the user for now. But we need to reset this register
+ * if the user updates RShunt or max expected current after driver
+ * init, e.g upon reading an EEPROM/Probe-type value.
+ */
+static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
+{
+   unsigned int rshunt = DIV_ROUND_CLOSEST(chip->shunt_resistor, 1000);
+   u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
+chip->current_lsb * rshunt);
+
+   return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
+}
+
+static int ina2xx_set_scale(struct ina2xx_chip_info *chip, unsigned int val)
+{
+   if (val <= 0 || val > chip->config->calibration_factor)
+   return -EINVAL;
+
+   chip->current_lsb = val;
+   chip->power_lsb = chip->current_ls

[PATCH v2 0/4] Make max expected current configurable for ina2xx drivers

2017-10-12 Thread Maciej Purski 
Hi all,

this patchset makes it possible to calibrate ina2xx drivers with different
calibration values, which are calculated using max expected current value.
It can be read from device tree, platform data or changed during run-time
using sysfs. If it isn't specified in device tree or platform data, the
driver uses default value, thanks to which the behaviour of the driver
doesn't change in this case.

There are two drivers for ina2xx: hwmon and iio. Changes are made
for both of them and their bindings as well.

These changes allow setting sensor's precision to the required by the board.
It is useful in Odroid XU3. Therefore this patchset also sets
max-expected-current in OdroidXU3 device tree to values from documentation.

Best Regards,

Maciej Purski

---
Changes in v2:
- make scale attribute for current iio channel writable as instead of
  adding new attribute max_expected_current
- use currX_max standard attribute in hwmon instead of adding new
  attribute
- fix max expected current property name
- update commit messages

Maciej Purski (4):
  iio: adc: ina2xx: Make max expected current configurable
  hwmon: (ina2xx) Make max expected current configurable
  dt-bindings: hwmon: Add ti-max-expected-current-microamp property to
ina2xx
  ARM: dts: Add ti-max-expected-current-microamp properties for ina231
in Odroid XU3

 Documentation/devicetree/bindings/hwmon/ina2xx.txt |   4 +-
 Documentation/hwmon/ina2xx |   3 +
 arch/arm/boot/dts/exynos5422-odroidxu3.dts |   4 +
 drivers/hwmon/ina2xx.c | 106 ++---
 drivers/iio/adc/ina2xx-adc.c   |  97 ++-
 include/linux/platform_data/ina2xx.h   |   2 +
 6 files changed, 178 insertions(+), 38 deletions(-)

-- 
2.7.4

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Re: [PATCH 1/4] iio: adc: ina2xx: Make max expected current configurable

2017-10-11 Thread Maciej Purski 



On 10/09/2017 03:35 PM, Jonathan Cameron wrote:

On Mon, 9 Oct 2017 10:08:42 +0200
Maciej Purski <m.pur...@samsung.com> wrote:


On 10/08/2017 11:47 AM, Jonathan Cameron wrote:

On Wed, 04 Oct 2017 09:11:31 +0200
Maciej Purski <m.pur...@samsung.com> wrote:
   

On 10/01/2017 12:29 PM, Jonathan Cameron wrote:

On Thu, 28 Sep 2017 14:50:12 +0200
Maciej Purski <m.pur...@samsung.com> wrote:
  

Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet.
Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model.

Make max expected current configurable, just like it's already done
with shunt resistance: from device tree, platform_data or later
from sysfs. On each max_expected_current change, calculate new values
for Current LSB and Power LSB. According to datasheet Current LSB should
be calculated by dividing max expected current by 2^15, as values read
from device registers are in this case 16-bit integers. Power LSB
is calculated by multiplying Current LSB by a factor, which is defined
in ina documentation.


One odd bit of casting inline.  Also this is new userspace ABI.
It needs documenting in

Documentation/ABI/testing/sysfs-bus-iio* as appropriate.
I'm also unclear on one element about this - is it a value used only
for calibration or are we talking about the actual 'range' of the device?
  


This is used for calibration. The device measures directly only voltage.
However, it has also current and power registers. Their values are
calculated by the device using the calibration register which is calculated
using max expected current. So I guess that it's not what you mean
by the actual 'range' of the device.
  

The interpretation of this value isn't clear against the more general
ABI.

In particular it is it in raw units (adc counts) or mA?  Docs say
that but the naming of the attribute doesn't make this clear.
  


It's in mA. I can make it clear in the attribute name.
  

Also I'm unconvinced this isn't better represented using the
range specifications available for any IIO attribute on the raw
value in combination with adjusting the scale value.
Note not many drivers yet provide ranges on their raw outputs
but we do have core support for it.  I've been meaning to start
pushing this out into drivers, but been busy since we introduced
the core support.  The dpot-dac driver does use it for examplel
 



I'm not sure if what I'm about to add is similar to what is done
in the mentioned dpot-dac driver. It seems that the callback read_avail
returns information on raw values which can be obtained from the device.
What I need is an adjustable value, which is then used by the device internally
in order to calculate current with the requested precision. Max expected current
is also used for calculating the scale value.
Tell me if I'm wrong. Maybe I misunderstood the 'range' concept in IIO and
your solution fits in here.
  


I think I answered this in the other branch of the thread.
_calibscale is what you want here as it's internal to the device.

It's not one often used for ADCs but quite a few other types of
device provide some front end analog adjustment (whilst it is digital
here, it is applied within the device - so we don't need to care).

Jonathan


Thank you for your explanation. Calibscale seems suitable for me in this case,
but what do you think I should do then with SCALE attribute? Should I get rid of
it for current and use only calibscale? Or should I use both calibscale and
scale attributes and for current they will be the same value?


You'll have to leave it as it is existing ABI.  It won't have the same value
as calibscale.  Calibscale is for internal changes that don't effect the raw
value.  scale is to be applied by userspace to the raw value. As I understand it
here the calibscale value should have no effect on scale.



Sorry, but now I'm a little bit confused. Which value would you
like me to substitute with calibscale - max_expected_current or current_lsb?
Both values do have effect on the scale, as scale is basically
current_lsb / 1000 and on the raw value, as current register is calculated
internally using current_lsb.

The content of current register is always RAW unless we set current_lsb to 1. 
See the documentation:

http://www.ti.com/lit/ds/symlink/ina231.pdf
page 15

Thanks,

Maciej



I should mention that currenst_lsb value is also used for calculating power_lsb
as they have a fixed ratio (20 or 25) given in the documentation.


Then expose it for power as well (appropriately adjusted).
In IIO ABI it is fine to have two elements addressing the same underlying 
hardware
value - rule is you change something, you check everything else hasn't changed.

Jonathan >>

Thanks,

Maciej

   

Best regards,

Macie

Re: [PATCH 1/4] iio: adc: ina2xx: Make max expected current configurable

2017-10-09 Thread Maciej Purski 



On 10/08/2017 11:47 AM, Jonathan Cameron wrote:

On Wed, 04 Oct 2017 09:11:31 +0200
Maciej Purski <m.pur...@samsung.com> wrote:


On 10/01/2017 12:29 PM, Jonathan Cameron wrote:

On Thu, 28 Sep 2017 14:50:12 +0200
Maciej Purski <m.pur...@samsung.com> wrote:
   

Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet.
Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model.

Make max expected current configurable, just like it's already done
with shunt resistance: from device tree, platform_data or later
from sysfs. On each max_expected_current change, calculate new values
for Current LSB and Power LSB. According to datasheet Current LSB should
be calculated by dividing max expected current by 2^15, as values read
from device registers are in this case 16-bit integers. Power LSB
is calculated by multiplying Current LSB by a factor, which is defined
in ina documentation.


One odd bit of casting inline.  Also this is new userspace ABI.
It needs documenting in

Documentation/ABI/testing/sysfs-bus-iio* as appropriate.
I'm also unclear on one element about this - is it a value used only
for calibration or are we talking about the actual 'range' of the device?
   


This is used for calibration. The device measures directly only voltage.
However, it has also current and power registers. Their values are
calculated by the device using the calibration register which is calculated
using max expected current. So I guess that it's not what you mean
by the actual 'range' of the device.


The interpretation of this value isn't clear against the more general
ABI.

In particular it is it in raw units (adc counts) or mA?  Docs say
that but the naming of the attribute doesn't make this clear.
   


It's in mA. I can make it clear in the attribute name.


Also I'm unconvinced this isn't better represented using the
range specifications available for any IIO attribute on the raw
value in combination with adjusting the scale value.
Note not many drivers yet provide ranges on their raw outputs
but we do have core support for it.  I've been meaning to start
pushing this out into drivers, but been busy since we introduced
the core support.  The dpot-dac driver does use it for examplel
  



I'm not sure if what I'm about to add is similar to what is done
in the mentioned dpot-dac driver. It seems that the callback read_avail
returns information on raw values which can be obtained from the device.
What I need is an adjustable value, which is then used by the device internally
in order to calculate current with the requested precision. Max expected current
is also used for calculating the scale value.
Tell me if I'm wrong. Maybe I misunderstood the 'range' concept in IIO and
your solution fits in here.



I think I answered this in the other branch of the thread.
_calibscale is what you want here as it's internal to the device.

It's not one often used for ADCs but quite a few other types of
device provide some front end analog adjustment (whilst it is digital
here, it is applied within the device - so we don't need to care).

Jonathan


Thank you for your explanation. Calibscale seems suitable for me in this case,
but what do you think I should do then with SCALE attribute? Should I get rid of 
it for current and use only calibscale? Or should I use both calibscale and 
scale attributes and for current they will be the same value?


I should mention that currenst_lsb value is also used for calculating power_lsb
as they have a fixed ratio (20 or 25) given in the documentation.

Thanks,

Maciej




Best regards,

Maciej

This moves the burden of calculating the 1lsb value to userspace,
but importantly it would give us a consistent ABI where this fits
in with existing elements (largely buy not introducing any new
ones :).

Thanks,

Jonathan


Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
   drivers/iio/adc/ina2xx-adc.c | 110 
++-
   include/linux/platform_data/ina2xx.h |   2 +
   2 files changed, 98 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index f387b97..883fede 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -56,6 +56,7 @@
   #define INA226_DEFAULT_IT1110
   
   #define INA2XX_RSHUNT_DEFAULT   1

+#define INA2XX_MAX_EXPECTED_A_DEFAULT  (1 << 15) /* current_lsb = 1 mA */
   
   /*

* bit masks for reading the settings in the configuration register
@@ -114,7 +115,7 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
enum ina2xx_ids chip_id;
   };
   
@@

Re: [PATCH 3/4] dt-bindings: hwmon: Add max-expected-current property to ina2xx

2017-10-05 Thread Maciej Purski 

On 10/01/2017 12:31 PM, Jonathan Cameron wrote:

On Thu, 28 Sep 2017 14:50:14 +0200
Maciej Purski <m.pur...@samsung.com> wrote:


Add optional max expected current property which allows calibrating
the ina sensor in order to achieve requested precision. Document
the changes in Documentation/hwmon/ina2xx.



This is introducing new generic devicetree bindings..
I'm not totally sure we want to do this rather than having a
manufacturer specific binding...  I don't have a good feeling for
how common this will be in other devices.

If it's generic, then this isn't necessarily the place to define it.

Jonathan



I agree, this should be manufacturer-specific property. Thanks.


Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
  Documentation/devicetree/bindings/hwmon/ina2xx.txt | 4 +++-
  Documentation/hwmon/ina2xx | 9 +
  2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/hwmon/ina2xx.txt 
b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
index 02af0d9..25ba372 100644
--- a/Documentation/devicetree/bindings/hwmon/ina2xx.txt
+++ b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
@@ -14,11 +14,13 @@ Optional properties:
  
  - shunt-resistor

Shunt resistor value in micro-Ohm
-
+- max-expected-current
+   Max expected current value in mA
  Example:
  
  ina220@44 {

compatible = "ti,ina220";
reg = <0x44>;
shunt-resistor = <1000>;
+   max-expected-current = <3000>;
  };
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index cfd31d9..e9ca838 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -51,10 +51,11 @@ INA230 and INA231 are high or low side current shunt and 
power monitors
  with an I2C interface. The chips monitor both a shunt voltage drop and
  bus supply voltage.
  
-The shunt value in micro-ohms can be set via platform data or device tree at

-compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
-refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
-if the device tree is used.
+The shunt value in micro-ohms and max expected current in mA can be set
+via platform data or device tree at compile-time or via the shunt_resistor
+and max_expected_current attributes in sysfs at run-time. Please refer to the
+Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings if the
+device tree is used.
  
  Additionally ina226 supports update_interval attribute as described in

  Documentation/hwmon/sysfs-interface. Internally the interval is the sum of






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Re: [PATCH 1/4] iio: adc: ina2xx: Make max expected current configurable

2017-10-04 Thread Maciej Purski 


On 10/01/2017 12:29 PM, Jonathan Cameron wrote:

On Thu, 28 Sep 2017 14:50:12 +0200
Maciej Purski <m.pur...@samsung.com> wrote:


Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet.
Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model.

Make max expected current configurable, just like it's already done
with shunt resistance: from device tree, platform_data or later
from sysfs. On each max_expected_current change, calculate new values
for Current LSB and Power LSB. According to datasheet Current LSB should
be calculated by dividing max expected current by 2^15, as values read
from device registers are in this case 16-bit integers. Power LSB
is calculated by multiplying Current LSB by a factor, which is defined
in ina documentation.


One odd bit of casting inline.  Also this is new userspace ABI.
It needs documenting in

Documentation/ABI/testing/sysfs-bus-iio* as appropriate.
I'm also unclear on one element about this - is it a value used only
for calibration or are we talking about the actual 'range' of the device?



This is used for calibration. The device measures directly only voltage.
However, it has also current and power registers. Their values are
calculated by the device using the calibration register which is calculated
using max expected current. So I guess that it's not what you mean
by the actual 'range' of the device.


The interpretation of this value isn't clear against the more general
ABI.

In particular it is it in raw units (adc counts) or mA?  Docs say
that but the naming of the attribute doesn't make this clear.



It's in mA. I can make it clear in the attribute name.


Also I'm unconvinced this isn't better represented using the
range specifications available for any IIO attribute on the raw
value in combination with adjusting the scale value.
Note not many drivers yet provide ranges on their raw outputs
but we do have core support for it.  I've been meaning to start
pushing this out into drivers, but been busy since we introduced
the core support.  The dpot-dac driver does use it for examplel




I'm not sure if what I'm about to add is similar to what is done
in the mentioned dpot-dac driver. It seems that the callback read_avail
returns information on raw values which can be obtained from the device.
What I need is an adjustable value, which is then used by the device internally
in order to calculate current with the requested precision. Max expected current
is also used for calculating the scale value.
Tell me if I'm wrong. Maybe I misunderstood the 'range' concept in IIO and
your solution fits in here.

Best regards,

Maciej

This moves the burden of calculating the 1lsb value to userspace,
but importantly it would give us a consistent ABI where this fits
in with existing elements (largely buy not introducing any new
ones :).

Thanks,

Jonathan


Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
  drivers/iio/adc/ina2xx-adc.c | 110 ++-
  include/linux/platform_data/ina2xx.h |   2 +
  2 files changed, 98 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index f387b97..883fede 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -56,6 +56,7 @@
  #define INA226_DEFAULT_IT 1110
  
  #define INA2XX_RSHUNT_DEFAULT   1

+#define INA2XX_MAX_EXPECTED_A_DEFAULT  (1 << 15) /* current_lsb = 1 mA */
  
  /*

   * bit masks for reading the settings in the configuration register
@@ -114,7 +115,7 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
enum ina2xx_ids chip_id;
  };
  
@@ -123,7 +124,10 @@ struct ina2xx_chip_info {

struct task_struct *task;
const struct ina2xx_config *config;
struct mutex state_lock;
-   unsigned int shunt_resistor;
+   unsigned int shunt_resistor;/* uOhms */
+   unsigned int max_expected_current;  /* mA */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
int avg;
int int_time_vbus; /* Bus voltage integration time uS */
int int_time_vshunt; /* Shunt voltage integration time uS */
@@ -137,7 +141,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
.chip_id = ina219,
},
[ina226] = {
@@ -146,7 +150,7 @@ static const struct ina2xx_co

[PATCH 3/4] dt-bindings: hwmon: Add max-expected-current property to ina2xx

2017-09-28 Thread Maciej Purski 
Add optional max expected current property which allows calibrating
the ina sensor in order to achieve requested precision. Document
the changes in Documentation/hwmon/ina2xx.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 Documentation/devicetree/bindings/hwmon/ina2xx.txt | 4 +++-
 Documentation/hwmon/ina2xx | 9 +
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/hwmon/ina2xx.txt 
b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
index 02af0d9..25ba372 100644
--- a/Documentation/devicetree/bindings/hwmon/ina2xx.txt
+++ b/Documentation/devicetree/bindings/hwmon/ina2xx.txt
@@ -14,11 +14,13 @@ Optional properties:
 
 - shunt-resistor
Shunt resistor value in micro-Ohm
-
+- max-expected-current
+   Max expected current value in mA
 Example:
 
 ina220@44 {
compatible = "ti,ina220";
reg = <0x44>;
shunt-resistor = <1000>;
+   max-expected-current = <3000>;
 };
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index cfd31d9..e9ca838 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -51,10 +51,11 @@ INA230 and INA231 are high or low side current shunt and 
power monitors
 with an I2C interface. The chips monitor both a shunt voltage drop and
 bus supply voltage.
 
-The shunt value in micro-ohms can be set via platform data or device tree at
-compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
-refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
-if the device tree is used.
+The shunt value in micro-ohms and max expected current in mA can be set
+via platform data or device tree at compile-time or via the shunt_resistor
+and max_expected_current attributes in sysfs at run-time. Please refer to the
+Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings if the
+device tree is used.
 
 Additionally ina226 supports update_interval attribute as described in
 Documentation/hwmon/sysfs-interface. Internally the interval is the sum of
-- 
2.7.4

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[PATCH 4/4] ARM: dts: Add max-expected-current properties for ina231 in Odroid XU3

2017-09-28 Thread Maciej Purski 
Set max-expected-current to values required by the documentation,
in order to achieve desired precision.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 arch/arm/boot/dts/exynos5422-odroidxu3.dts | 4 
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/exynos5422-odroidxu3.dts 
b/arch/arm/boot/dts/exynos5422-odroidxu3.dts
index 9ed6564..aa19374 100644
--- a/arch/arm/boot/dts/exynos5422-odroidxu3.dts
+++ b/arch/arm/boot/dts/exynos5422-odroidxu3.dts
@@ -28,6 +28,7 @@
compatible = "ti,ina231";
reg = <0x40>;
shunt-resistor = <1>;
+   max-expected-current = <9000>;
};
 
/* memory: VDD_MEM */
@@ -35,6 +36,7 @@
compatible = "ti,ina231";
reg = <0x41>;
shunt-resistor = <1>;
+   max-expected-current = <3000>;
};
 
/* GPU: VDD_G3D */
@@ -42,6 +44,7 @@
compatible = "ti,ina231";
reg = <0x44>;
shunt-resistor = <1>;
+   max-expected-current = <5000>;
};
 
/* A7 cluster: VDD_KFC */
@@ -49,6 +52,7 @@
compatible = "ti,ina231";
reg = <0x45>;
shunt-resistor = <1>;
+   max-expected-current = <2000>;
};
 };
 
-- 
2.7.4

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[PATCH 2/4] hwmon: (ina2xx) Make max expected current configurable

2017-09-28 Thread Maciej Purski 
Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet.
Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model.

Make max expected current configurable, just like it's already done
with shunt resistance: from device tree, platform_data or later
from sysfs. On each max_expected_current change, calculate new values
for Current LSB and Power LSB. According to datasheet Current LSB should
be calculated by dividing max expected current by 2^15, as values read
from device registers are in this case 16-bit integers. Power LSB
is calculated by multiplying Current LSB by a factor, which is defined
in ina documentation.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 drivers/hwmon/ina2xx.c | 105 +++--
 1 file changed, 93 insertions(+), 12 deletions(-)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 62e38fa..d956013 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -80,6 +80,8 @@
 /* common attrs, ina226 attrs and NULL */
 #define INA2XX_MAX_ATTRIBUTE_GROUPS3
 
+#define INA2XX_MAX_EXPECTED_A_DEFAULT  (1 << 15)   /* current_lsb = 1 mA */
+
 /*
  * Both bus voltage and shunt voltage conversion times for ina226 are set
  * to 0b0100 on POR, which translates to 2200 microseconds in total.
@@ -100,13 +102,16 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
 };
 
 struct ina2xx_data {
const struct ina2xx_config *config;
 
-   long rshunt;
+   long rshunt;/* uOhms */
+   unsigned int max_expected_current;  /* mA */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
struct mutex config_lock;
struct regmap *regmap;
 
@@ -121,7 +126,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
},
[ina226] = {
.config_default = INA226_CONFIG_DEFAULT,
@@ -130,7 +135,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
-   .power_lsb = 25000,
+   .power_lsb_factor = 25,
},
 };
 
@@ -169,10 +174,17 @@ static u16 ina226_interval_to_reg(int interval)
return INA226_SHIFT_AVG(avg_bits);
 }
 
+/*
+ * Calculate calibration value according to equation 1 in ina226 datasheet
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ * Current LSB is in uA and RShunt is in uOhms, so in order to keep
+ * calibration value scaled RShunt must be converted to mOhms.
+ */
 static int ina2xx_calibrate(struct ina2xx_data *data)
 {
+   int r_shunt = DIV_ROUND_CLOSEST(data->rshunt, 1000);
u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor,
-   data->rshunt);
+   data->current_lsb * r_shunt);
 
return regmap_write(data->regmap, INA2XX_CALIBRATION, val);
 }
@@ -187,13 +199,28 @@ static int ina2xx_init(struct ina2xx_data *data)
if (ret < 0)
return ret;
 
-   /*
-* Set current LSB to 1mA, shunt is in uOhms
-* (equation 13 in datasheet).
-*/
return ina2xx_calibrate(data);
 }
 
+/*
+ * Set max_expected_current (mA) and calculate current_lsb (uA),
+ * according to equation 2 in ina226 datasheet. Power LSB is calculated
+ * by multiplying Current LSB by a given factor, which may vary depending
+ * on ina version.
+ */
+static int set_max_expected_current(struct ina2xx_data *data, unsigned int val)
+{
+   if (val <= 0 || val > data->config->calibration_factor)
+   return -EINVAL;
+
+   data->max_expected_current = val;
+   data->current_lsb = DIV_ROUND_CLOSEST(data->max_expected_current * 1000,
+ 1 << 15);
+   data->power_lsb = data->current_lsb * data->config->power_lsb_factor;
+
+   return 0;
+}
+
 static int ina2xx_read_reg(struct device *dev, int reg, unsigned int *regval)
 {
struct ina2xx_data *data = dev_get_drvdata(dev);
@@ -268,11 +295,11 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 
reg,
val = DIV_ROUND_CLOSEST(val, 1000);
break;
case INA2XX_POWER:
-   val = regval * data->config->power_lsb;
+   val

[PATCH 1/4] iio: adc: ina2xx: Make max expected current configurable

2017-09-28 Thread Maciej Purski 
Max expected current is used for calculating calibration register value,
Current LSB and Power LSB according to equations found in ina datasheet.
Max expected current is now implicitly set to default value,
which is 2^15, thanks to which Current LSB is equal to 1 mA and
Power LSB is equal to 2 uW or 25000 uW depending on ina model.

Make max expected current configurable, just like it's already done
with shunt resistance: from device tree, platform_data or later
from sysfs. On each max_expected_current change, calculate new values
for Current LSB and Power LSB. According to datasheet Current LSB should
be calculated by dividing max expected current by 2^15, as values read
from device registers are in this case 16-bit integers. Power LSB
is calculated by multiplying Current LSB by a factor, which is defined
in ina documentation.

Signed-off-by: Maciej Purski <m.pur...@samsung.com>
---
 drivers/iio/adc/ina2xx-adc.c | 110 ++-
 include/linux/platform_data/ina2xx.h |   2 +
 2 files changed, 98 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index f387b97..883fede 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -56,6 +56,7 @@
 #define INA226_DEFAULT_IT  1110
 
 #define INA2XX_RSHUNT_DEFAULT   1
+#define INA2XX_MAX_EXPECTED_A_DEFAULT  (1 << 15)   /* current_lsb = 1 mA */
 
 /*
  * bit masks for reading the settings in the configuration register
@@ -114,7 +115,7 @@ struct ina2xx_config {
int shunt_div;
int bus_voltage_shift;
int bus_voltage_lsb;/* uV */
-   int power_lsb;  /* uW */
+   int power_lsb_factor;
enum ina2xx_ids chip_id;
 };
 
@@ -123,7 +124,10 @@ struct ina2xx_chip_info {
struct task_struct *task;
const struct ina2xx_config *config;
struct mutex state_lock;
-   unsigned int shunt_resistor;
+   unsigned int shunt_resistor;/* uOhms */
+   unsigned int max_expected_current;  /* mA */
+   int current_lsb;/* uA */
+   int power_lsb;  /* uW */
int avg;
int int_time_vbus; /* Bus voltage integration time uS */
int int_time_vshunt; /* Shunt voltage integration time uS */
@@ -137,7 +141,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 100,
.bus_voltage_shift = 3,
.bus_voltage_lsb = 4000,
-   .power_lsb = 2,
+   .power_lsb_factor = 20,
.chip_id = ina219,
},
[ina226] = {
@@ -146,7 +150,7 @@ static const struct ina2xx_config ina2xx_config[] = {
.shunt_div = 400,
.bus_voltage_shift = 0,
.bus_voltage_lsb = 1250,
-   .power_lsb = 25000,
+   .power_lsb_factor = 25,
.chip_id = ina226,
},
 };
@@ -210,14 +214,15 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 
case INA2XX_POWER:
/* processed (mW) = raw*lsb (uW) / 1000 */
-   *val = chip->config->power_lsb;
+   *val = chip->power_lsb;
*val2 = 1000;
return IIO_VAL_FRACTIONAL;
 
case INA2XX_CURRENT:
-   /* processed (mA) = raw (mA) */
-   *val = 1;
-   return IIO_VAL_INT;
+   /* processed (mA) = raw*lsb (uA) / 1000 */
+   *val = chip->current_lsb;
+   *val2 = 1000;
+   return IIO_VAL_FRACTIONAL;
}
}
 
@@ -434,24 +439,47 @@ static ssize_t ina2xx_allow_async_readout_store(struct 
device *dev,
 }
 
 /*
- * Set current LSB to 1mA, shunt is in uOhms
- * (equation 13 in datasheet). We hardcode a Current_LSB
- * of 1.0 x10-6. The only remaining parameter is RShunt.
+ * Calculate calibration value according to equation 1 in ina226 datasheet
+ * http://www.ti.com/lit/ds/symlink/ina226.pdf.
+ * Current LSB is in uA and RShunt is in uOhms, so RShunt should be
+ * converted to mOhms in order to keep the scale.
  * There is no need to expose the CALIBRATION register
  * to the user for now. But we need to reset this register
- * if the user updates RShunt after driver init, e.g upon
- * reading an EEPROM/Probe-type value.
+ * if the user updates RShunt or max expected current after driver
+ * init, e.g upon reading an EEPROM/Probe-type value.
  */
 static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
 {
+   unsigned int rshunt = DIV_ROUND_CLOSEST(chip->shunt_resistor, 1000);
u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
-  chip->shunt_resistor);
+chip->current_lsb *

[PATCH 0/4] Make max expected current configurable for ina2xx drivers

2017-09-28 Thread Maciej Purski 
Hi all,

this patchset makes it possible to calibrate ina2xx drivers with different
calibration values, which are calculated using max expected current value.
It can be read from device tree, platform data or changed during run-time
using sysfs. If it isn't specified in device tree or platform data, the
driver uses default value, thanks to which the behaviour of the driver
don't change in this case.

There are two drivers for ina2xx: hwmon and iio. Changes are made
for both of them and their bindings as well.

These changes allow setting sensor's precision to the required by the board.
It is useful in Odroid XU3. Therefore this patchset also sets
max-expected-current in OdroidXU3 device tree to values from documentation.

Best Regards,

Maciej Purski

Maciej Purski (4):
  iio: adc: ina2xx: Make max expected current configurable
  hwmon: (ina2xx) Make max expected current configurable
  dt-bindings: hwmon: Add max-expected-current property to ina2xx
  ARM: dts: Add max-expected-current properties for ina231 in Odroid XU3

 Documentation/devicetree/bindings/hwmon/ina2xx.txt |   4 +-
 Documentation/hwmon/ina2xx |   9 +-
 arch/arm/boot/dts/exynos5422-odroidxu3.dts |   4 +
 drivers/hwmon/ina2xx.c | 105 +---
 drivers/iio/adc/ina2xx-adc.c   | 110 ++---
 include/linux/platform_data/ina2xx.h   |   2 +
 6 files changed, 203 insertions(+), 31 deletions(-)

-- 
2.7.4

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