Added the ability to specify the value of the shunt resistor in the
device tree instead of assuming it is 1 milliOhm.
Would be good to backport as well
Cormier, Jonathan (1):
dt-bindings: hwmon: adi,ltc2945: Add binding
John Pruitt (1):
hwmon: ltc2945: Allow setting shunt resistor
.../bindings/hwmon/adi,ltc2945.yaml | 50 +++++++++++
drivers/hwmon/ltc2945.c | 86 ++++++++++++++-----
2 files changed, 115 insertions(+), 21 deletions(-)
create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
--
2.25.1
From: John Pruitt <[email protected]>
Added the ability to specify the value of the shunt resistor in the
device tree instead of assuming it is 1 milliOhm. The value in the
device tree has the name shunt-resistor-micro-ohms and the
default value is 1000 micro-ohms in order to preserve the
current behavior.
Signed-off-by: "Cormier, Jonathan" <[email protected]>
Signed-off-by: John Pruitt <[email protected]>
---
drivers/hwmon/ltc2945.c | 86 +++++++++++++++++++++++++++++++----------
1 file changed, 65 insertions(+), 21 deletions(-)
diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
index 9adebb59f604..4e8b92e53133 100644
--- a/drivers/hwmon/ltc2945.c
+++ b/drivers/hwmon/ltc2945.c
@@ -58,6 +58,11 @@
#define CONTROL_MULT_SELECT (1 << 0)
#define CONTROL_TEST_MODE (1 << 4)
+struct ltc2945_data {
+ struct regmap *regmap;
+ u32 shunt_resistor; // number of microohms
+};
+
static inline bool is_power_reg(u8 reg)
{
return reg < LTC2945_SENSE_H;
@@ -66,7 +71,9 @@ static inline bool is_power_reg(u8 reg)
/* Return the value from the given register in uW, mV, or mA */
static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
{
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
+ u32 shunt_resistor = data->shunt_resistor;
unsigned int control;
u8 buf[3];
long long val;
@@ -93,8 +100,11 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
case LTC2945_MIN_POWER_THRES_H:
/*
* Convert to uW by assuming current is measured with
- * an 1mOhm sense resistor, similar to current
- * measurements.
+ * a 1000 microOhm sense resistor (aka shunt resistor)
+ * or what is specified in DT, similar to current
+ * measurements. The shunt_resistor value is in
+ * microOhms.
+ *
* Control register bit 0 selects if voltage at SENSE+/VDD
* or voltage at ADIN is used to measure power.
*/
@@ -108,6 +118,8 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
val = (val * 25LL) >> 1;
}
+ val *= 1000;
+ val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
break;
case LTC2945_VIN_H:
case LTC2945_MAX_VIN_H:
@@ -132,12 +144,15 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
case LTC2945_MIN_SENSE_THRES_H:
/*
* 25 uV resolution. Convert to current as measured with
- * an 1 mOhm sense resistor, in mA. If a different sense
- * resistor is installed, calculate the actual current by
- * dividing the reported current by the sense resistor value
- * in mOhm.
+ * an 1000 microOhm sense (or shunt) resistor, in mA.
+ * If a different shunt resistor is installed, calculate
+ * the actual current by dividing the reported current
+ * by the shunt resistor value in microOhms. The actual
+ * The actual shunt resistor value can be specified
+ * in the device tree.
*/
- val *= 25;
+ val *= 25 * 1000;
+ val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
break;
default:
return -EINVAL;
@@ -148,7 +163,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
static int ltc2945_val_to_reg(struct device *dev, u8 reg,
unsigned long val)
{
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
+ u32 shunt_resistor = data->shunt_resistor;
unsigned int control;
int ret;
@@ -160,8 +177,10 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
case LTC2945_MIN_POWER_THRES_H:
/*
* Convert to register value by assuming current is measured
- * with an 1mOhm sense resistor, similar to current
+ * with a 1000 microOhm sense resistor, (aka shunt resistor)
+ * or what is specified in DT, similar to current
* measurements.
+ *
* Control register bit 0 selects if voltage at SENSE+/VDD
* or voltage at ADIN is used to measure power, which in turn
* determines register calculations.
@@ -171,14 +190,16 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
return ret;
if (control & CONTROL_MULT_SELECT) {
/* 25 mV * 25 uV = 0.625 uV resolution. */
- val = DIV_ROUND_CLOSEST(val, 625);
+ val *= shunt_resistor;
+ val = DIV_ROUND_CLOSEST(val, 625 * 1000);
} else {
/*
* 0.5 mV * 25 uV = 0.0125 uV resolution.
* Divide first to avoid overflow;
* accept loss of accuracy.
*/
- val = DIV_ROUND_CLOSEST(val, 25) * 2;
+ val *= shunt_resistor;
+ val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
}
break;
case LTC2945_VIN_H:
@@ -204,12 +225,14 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
case LTC2945_MIN_SENSE_THRES_H:
/*
* 25 uV resolution. Convert to current as measured with
- * an 1 mOhm sense resistor, in mA. If a different sense
- * resistor is installed, calculate the actual current by
- * dividing the reported current by the sense resistor value
- * in mOhm.
+ * a 1000 microOhm sense (or shunt) resistor, in mA. If
+ * a different shunt resistor is installed, calculate
+ * the actual current by dividing the reported current
+ * by the sense resistor value in microOhms. The actual
+ * shunt resistor value can be specified in the device tree.
*/
- val = DIV_ROUND_CLOSEST(val, 25);
+ val *= shunt_resistor;
+ val = DIV_ROUND_CLOSEST(val, 25 * 1000);
break;
default:
return -EINVAL;
@@ -234,7 +257,8 @@ static ssize_t ltc2945_value_store(struct device *dev,
const char *buf, size_t count)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
u8 reg = attr->index;
unsigned long val;
u8 regbuf[3];
@@ -269,7 +293,8 @@ static ssize_t ltc2945_history_store(struct device *dev,
const char *buf, size_t count)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
u8 reg = attr->index;
int num_regs = is_power_reg(reg) ? 3 : 2;
u8 buf_min[3] = { 0xff, 0xff, 0xff };
@@ -321,7 +346,8 @@ static ssize_t ltc2945_bool_show(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
unsigned int fault;
int ret;
@@ -450,6 +476,14 @@ static int ltc2945_probe(struct i2c_client *client)
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct regmap *regmap;
+ u32 shunt_resistor;
+
+ struct ltc2945_data *data;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+ dev_set_drvdata(dev, data);
regmap = devm_regmap_init_i2c(client, <c2945_regmap_config);
if (IS_ERR(regmap)) {
@@ -457,11 +491,21 @@ static int ltc2945_probe(struct i2c_client *client)
return PTR_ERR(regmap);
}
+ data->regmap = regmap;
+ if (of_property_read_u32(client->dev.of_node,
+ "shunt-resistor-micro-ohms", &shunt_resistor))
+ shunt_resistor = 1000; /* 1000 micro-Ohm if not set via DT */
+
+ if (shunt_resistor == 0)
+ return -EINVAL;
+
+ data->shunt_resistor = shunt_resistor;
+
/* Clear faults */
regmap_write(regmap, LTC2945_FAULT, 0x00);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
- regmap,
+ data,
ltc2945_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
--
2.25.1
Signed-off-by: "Cormier, Jonathan" <[email protected]>
---
.../bindings/hwmon/adi,ltc2945.yaml | 50 +++++++++++++++++++
1 file changed, 50 insertions(+)
create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
diff --git a/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
new file mode 100644
index 000000000000..9ca7a886dec8
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/adi,ltc2945.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices LTC2945 wide range i2c power monitor
+
+maintainers:
+ - Guenter Roeck <[email protected]>
+
+description: |
+ Analog Devices LTC2945 wide range i2c power monitor over I2C.
+
+ https://www.analog.com/media/en/technical-documentation/data-sheets/LTC2945.pdf
+
+properties:
+ compatible:
+ enum:
+ - ltc2945
+
+ reg:
+ maxItems: 1
+
+ shunt-resistor-micro-ohms:
+ description:
+ Shunt resistor value in micro-Ohms
+ default: 1000
+
+required:
+ - compatible
+ - reg
+
+
+additionalProperties: false
+
+examples:
+ - |
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ ltc2945_i2c: ltc2945@6e {
+ compatible = "ltc2945";
+ reg = <0x6e>;
+ /* 10 milli-Ohm shunt resistor */
+ shunt-resistor-micro-ohms = <10000>;
+ };
+ };
+...
--
2.25.1
On 14/12/2022 23:07, Cormier, Jonathan wrote:
Missing commit msg. Describe hardware.
> Signed-off-by: "Cormier, Jonathan" <[email protected]>
> ---
> .../bindings/hwmon/adi,ltc2945.yaml | 50 +++++++++++++++++++
> 1 file changed, 50 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
>
> diff --git a/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
> new file mode 100644
> index 000000000000..9ca7a886dec8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
> @@ -0,0 +1,50 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwmon/adi,ltc2945.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices LTC2945 wide range i2c power monitor
> +
> +maintainers:
> + - Guenter Roeck <[email protected]>
> +
> +description: |
> + Analog Devices LTC2945 wide range i2c power monitor over I2C.
> +
> + https://www.analog.com/media/en/technical-documentation/data-sheets/LTC2945.pdf
> +
> +properties:
> + compatible:
> + enum:
> + - ltc2945
That's not a correct compatible. Missing vendor prefix.
> +
> + reg:
> + maxItems: 1
> +
> + shunt-resistor-micro-ohms:
> + description:
> + Shunt resistor value in micro-Ohms
> + default: 1000
> +
> +required:
> + - compatible
> + - reg
> +
> +
Just one blank line.
> +additionalProperties: false
> +
> +examples:
> + - |
> + i2c {
> + #address-cells = <1>;
> + #size-cells = <0>;
Use 4 spaces for example indentation.
> +
> + ltc2945_i2c: ltc2945@6e {
Node names should be generic.
https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
> + compatible = "ltc2945";
> + reg = <0x6e>;
> + /* 10 milli-Ohm shunt resistor */
> + shunt-resistor-micro-ohms = <10000>;
> + };
> + };
> +...
Best regards,
Krzysztof
Resending reply in plain text
On Thu, Dec 15, 2022 at 9:35 AM Jon Cormier <[email protected]> wrote:
>
> On Thu, Dec 15, 2022 at 4:42 AM Krzysztof Kozlowski <[email protected]> wrote:
>>
>> On 14/12/2022 23:07, Cormier, Jonathan wrote:
>>
>> Missing commit msg. Describe hardware.
>
> Thanks
>>
>>
>>
>>
>> > Signed-off-by: "Cormier, Jonathan" <[email protected]>
>> > ---
>> > .../bindings/hwmon/adi,ltc2945.yaml | 50 +++++++++++++++++++
>> > 1 file changed, 50 insertions(+)
>> > create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
>> >
>> > diff --git a/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
>> > new file mode 100644
>> > index 000000000000..9ca7a886dec8
>> > --- /dev/null
>> > +++ b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
>> > @@ -0,0 +1,50 @@
>> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> > +%YAML 1.2
>> > +---
>> > +$id: http://devicetree.org/schemas/hwmon/adi,ltc2945.yaml#
>> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> > +
>> > +title: Analog Devices LTC2945 wide range i2c power monitor
>> > +
>> > +maintainers:
>> > + - Guenter Roeck <[email protected]>
>> > +
>> > +description: |
>> > + Analog Devices LTC2945 wide range i2c power monitor over I2C.
>> > +
>> > + https://www.analog.com/media/en/technical-documentation/data-sheets/LTC2945.pdf
>> > +
>> > +properties:
>> > + compatible:
>> > + enum:
>> > + - ltc2945
>>
>> That's not a correct compatible. Missing vendor prefix.
>>
> Okay, I assume I'll need to update the driver as well to handle that.
>>
>> > +
>> > + reg:
>> > + maxItems: 1
>> > +
>> > + shunt-resistor-micro-ohms:
>> > + description:
>> > + Shunt resistor value in micro-Ohms
>> > + default: 1000
>> > +
>> > +required:
>> > + - compatible
>> > + - reg
>> > +
>> > +
>>
>> Just one blank line.
>>
>> > +additionalProperties: false
>> > +
>> > +examples:
>> > + - |
>> > + i2c {
>> > + #address-cells = <1>;
>> > + #size-cells = <0>;
>>
>> Use 4 spaces for example indentation.
>>
>> > +
>> > + ltc2945_i2c: ltc2945@6e {
>>
>> Node names should be generic.
>> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
>>
>> > + compatible = "ltc2945";
>> > + reg = <0x6e>;
>> > + /* 10 milli-Ohm shunt resistor */
>> > + shunt-resistor-micro-ohms = <10000>;
>> > + };
>> > + };
>> > +...
>>
>> Best regards,
>> Krzysztof
>>
>
>
> --
> Jonathan Cormier
> Software Engineer
>
> Voice: 315.425.4045 x222
>
>
>
> http://www.CriticalLink.com
> 6712 Brooklawn Parkway, Syracuse, NY 13211
>
>
--
Jonathan Cormier
Software Engineer
Voice: 315.425.4045 x222
http://www.CriticalLink.com
6712 Brooklawn Parkway, Syracuse, NY 13211
On 12/14/22 14:07, Cormier, Jonathan wrote:
> From: John Pruitt <[email protected]>
>
> Added the ability to specify the value of the shunt resistor in the
> device tree instead of assuming it is 1 milliOhm. The value in the
> device tree has the name shunt-resistor-micro-ohms and the
> default value is 1000 micro-ohms in order to preserve the
> current behavior.
>
Also needs a devicetree match table.
> Signed-off-by: "Cormier, Jonathan" <[email protected]>
> Signed-off-by: John Pruitt <[email protected]>
> ---
> drivers/hwmon/ltc2945.c | 86 +++++++++++++++++++++++++++++++----------
> 1 file changed, 65 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
> index 9adebb59f604..4e8b92e53133 100644
> --- a/drivers/hwmon/ltc2945.c
> +++ b/drivers/hwmon/ltc2945.c
> @@ -58,6 +58,11 @@
> #define CONTROL_MULT_SELECT (1 << 0)
> #define CONTROL_TEST_MODE (1 << 4)
>
> +struct ltc2945_data {
> + struct regmap *regmap;
> + u32 shunt_resistor; // number of microohms
No C++ comments in this code, please. Also, "number of" is not needed.
Something like "in microohms" or just "microohms" would be sufficient.
> +};
> +
> static inline bool is_power_reg(u8 reg)
> {
> return reg < LTC2945_SENSE_H;
> @@ -66,7 +71,9 @@ static inline bool is_power_reg(u8 reg)
> /* Return the value from the given register in uW, mV, or mA */
> static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> {
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> + u32 shunt_resistor = data->shunt_resistor;
> unsigned int control;
> u8 buf[3];
> long long val;
> @@ -93,8 +100,11 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> case LTC2945_MIN_POWER_THRES_H:
> /*
> * Convert to uW by assuming current is measured with
> - * an 1mOhm sense resistor, similar to current
> - * measurements.
> + * a 1000 microOhm sense resistor (aka shunt resistor)
> + * or what is specified in DT, similar to current
> + * measurements. The shunt_resistor value is in
> + * microOhms.
The units are already in the variable declaration. No need to repeat.
There is no need to replace "1 mOhm" with "1000 microOhm".
It might make sense to drop all those comments, add a kerneldoc comment
to struct ltc2945_data, and explain it all there.
> + *
> * Control register bit 0 selects if voltage at SENSE+/VDD
> * or voltage at ADIN is used to measure power.
> */
> @@ -108,6 +118,8 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> /* 0.5 mV * 25 uV = 0.0125 uV resolution. */
> val = (val * 25LL) >> 1;
> }
> + val *= 1000;
> + val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> break;
> case LTC2945_VIN_H:
> case LTC2945_MAX_VIN_H:
> @@ -132,12 +144,15 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> case LTC2945_MIN_SENSE_THRES_H:
> /*
> * 25 uV resolution. Convert to current as measured with
> - * an 1 mOhm sense resistor, in mA. If a different sense
> - * resistor is installed, calculate the actual current by
> - * dividing the reported current by the sense resistor value
> - * in mOhm.
> + * an 1000 microOhm sense (or shunt) resistor, in mA.
> + * If a different shunt resistor is installed, calculate
> + * the actual current by dividing the reported current
> + * by the shunt resistor value in microOhms. The actual
> + * The actual shunt resistor value can be specified
> + * in the device tree.
All but the last sentence just replace 1 mOhm with 1000 microOhm, which
does not add any value. Applies to all similar changes; I won't comment
on it anymore below.
> */
> - val *= 25;
> + val *= 25 * 1000;
> + val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> break;
> default:
> return -EINVAL;
> @@ -148,7 +163,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> unsigned long val)
> {
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> + u32 shunt_resistor = data->shunt_resistor;
> unsigned int control;
> int ret;
>
> @@ -160,8 +177,10 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> case LTC2945_MIN_POWER_THRES_H:
> /*
> * Convert to register value by assuming current is measured
> - * with an 1mOhm sense resistor, similar to current
> + * with a 1000 microOhm sense resistor, (aka shunt resistor)
> + * or what is specified in DT, similar to current
> * measurements.
> + *
> * Control register bit 0 selects if voltage at SENSE+/VDD
> * or voltage at ADIN is used to measure power, which in turn
> * determines register calculations.
> @@ -171,14 +190,16 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> return ret;
> if (control & CONTROL_MULT_SELECT) {
> /* 25 mV * 25 uV = 0.625 uV resolution. */
> - val = DIV_ROUND_CLOSEST(val, 625);
> + val *= shunt_resistor;
This can now easily result in an overflow.
> + val = DIV_ROUND_CLOSEST(val, 625 * 1000);
> } else {
> /*
> * 0.5 mV * 25 uV = 0.0125 uV resolution.
> * Divide first to avoid overflow;
> * accept loss of accuracy.
> */
> - val = DIV_ROUND_CLOSEST(val, 25) * 2;
> + val *= shunt_resistor;
> + val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
> }
> break;
> case LTC2945_VIN_H:
> @@ -204,12 +225,14 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> case LTC2945_MIN_SENSE_THRES_H:
> /*
> * 25 uV resolution. Convert to current as measured with
> - * an 1 mOhm sense resistor, in mA. If a different sense
> - * resistor is installed, calculate the actual current by
> - * dividing the reported current by the sense resistor value
> - * in mOhm.
> + * a 1000 microOhm sense (or shunt) resistor, in mA. If
> + * a different shunt resistor is installed, calculate
> + * the actual current by dividing the reported current
> + * by the sense resistor value in microOhms. The actual
> + * shunt resistor value can be specified in the device tree.
> */
> - val = DIV_ROUND_CLOSEST(val, 25);
> + val *= shunt_resistor;
Needs to ensure that there are no overflows. Try to write the maximum value
for unsigned long and see what happens.
> + val = DIV_ROUND_CLOSEST(val, 25 * 1000);
> break;
> default:
> return -EINVAL;
> @@ -234,7 +257,8 @@ static ssize_t ltc2945_value_store(struct device *dev,
> const char *buf, size_t count)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> u8 reg = attr->index;
> unsigned long val;
> u8 regbuf[3];
> @@ -269,7 +293,8 @@ static ssize_t ltc2945_history_store(struct device *dev,
> const char *buf, size_t count)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap; > u8 reg = attr->index;
> int num_regs = is_power_reg(reg) ? 3 : 2;
> u8 buf_min[3] = { 0xff, 0xff, 0xff };
> @@ -321,7 +346,8 @@ static ssize_t ltc2945_bool_show(struct device *dev,
> struct device_attribute *da, char *buf)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> unsigned int fault;
> int ret;
>
> @@ -450,6 +476,14 @@ static int ltc2945_probe(struct i2c_client *client)
> struct device *dev = &client->dev;
> struct device *hwmon_dev;
> struct regmap *regmap;
> + u32 shunt_resistor;
> +
drop this empty line
> + struct ltc2945_data *data;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> + dev_set_drvdata(dev, data);
>
> regmap = devm_regmap_init_i2c(client, <c2945_regmap_config);
> if (IS_ERR(regmap)) {
> @@ -457,11 +491,21 @@ static int ltc2945_probe(struct i2c_client *client)
> return PTR_ERR(regmap);
> }
>
> + data->regmap = regmap;
> + if (of_property_read_u32(client->dev.of_node,
> + "shunt-resistor-micro-ohms", &shunt_resistor))
Please consider using device_property_read_u32().
> + shunt_resistor = 1000; /* 1000 micro-Ohm if not set via DT */
"if not set via DT" -> "default value". With device_property_read_u32(),
this can be set by other means, not just DT.
> +
> + if (shunt_resistor == 0)
> + return -EINVAL;
> +
> + data->shunt_resistor = shunt_resistor;
> +
> /* Clear faults */
> regmap_write(regmap, LTC2945_FAULT, 0x00);
>
> hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
> - regmap,
> + data,
> ltc2945_groups);
> return PTR_ERR_OR_ZERO(hwmon_dev);
> }
On Thu, Dec 15, 2022 at 10:11 AM Guenter Roeck <[email protected]> wrote:
>
> On 12/14/22 14:07, Cormier, Jonathan wrote:
> > From: John Pruitt <[email protected]>
> >
> > Added the ability to specify the value of the shunt resistor in the
> > device tree instead of assuming it is 1 milliOhm. The value in the
> > device tree has the name shunt-resistor-micro-ohms and the
> > default value is 1000 micro-ohms in order to preserve the
> > current behavior.
> >
>
> Also needs a devicetree match table.
On it
>
> > Signed-off-by: "Cormier, Jonathan" <[email protected]>
> > Signed-off-by: John Pruitt <[email protected]>
> > ---
> > drivers/hwmon/ltc2945.c | 86 +++++++++++++++++++++++++++++++----------
> > 1 file changed, 65 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
> > index 9adebb59f604..4e8b92e53133 100644
> > --- a/drivers/hwmon/ltc2945.c
> > +++ b/drivers/hwmon/ltc2945.c
> > @@ -58,6 +58,11 @@
> > #define CONTROL_MULT_SELECT (1 << 0)
> > #define CONTROL_TEST_MODE (1 << 4)
> >
> > +struct ltc2945_data {
> > + struct regmap *regmap;
> > + u32 shunt_resistor; // number of microohms
>
> No C++ comments in this code, please. Also, "number of" is not needed.
> Something like "in microohms" or just "microohms" would be sufficient.
>
> > +};
> > +
> > static inline bool is_power_reg(u8 reg)
> > {
> > return reg < LTC2945_SENSE_H;
> > @@ -66,7 +71,9 @@ static inline bool is_power_reg(u8 reg)
> > /* Return the value from the given register in uW, mV, or mA */
> > static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> > {
> > - struct regmap *regmap = dev_get_drvdata(dev);
> > + struct ltc2945_data *data = dev_get_drvdata(dev);
> > + struct regmap *regmap = data->regmap;
> > + u32 shunt_resistor = data->shunt_resistor;
> > unsigned int control;
> > u8 buf[3];
> > long long val;
> > @@ -93,8 +100,11 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> > case LTC2945_MIN_POWER_THRES_H:
> > /*
> > * Convert to uW by assuming current is measured with
> > - * an 1mOhm sense resistor, similar to current
> > - * measurements.
> > + * a 1000 microOhm sense resistor (aka shunt resistor)
> > + * or what is specified in DT, similar to current
> > + * measurements. The shunt_resistor value is in
> > + * microOhms.
>
> The units are already in the variable declaration. No need to repeat.
> There is no need to replace "1 mOhm" with "1000 microOhm".
>
> It might make sense to drop all those comments, add a kerneldoc comment
> to struct ltc2945_data, and explain it all there.
Will do
>
> > + *
> > * Control register bit 0 selects if voltage at SENSE+/VDD
> > * or voltage at ADIN is used to measure power.
> > */
> > @@ -108,6 +118,8 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> > /* 0.5 mV * 25 uV = 0.0125 uV resolution. */
> > val = (val * 25LL) >> 1;
> > }
> > + val *= 1000;
> > + val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> > break;
> > case LTC2945_VIN_H:
> > case LTC2945_MAX_VIN_H:
> > @@ -132,12 +144,15 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> > case LTC2945_MIN_SENSE_THRES_H:
> > /*
> > * 25 uV resolution. Convert to current as measured with
> > - * an 1 mOhm sense resistor, in mA. If a different sense
> > - * resistor is installed, calculate the actual current by
> > - * dividing the reported current by the sense resistor value
> > - * in mOhm.
> > + * an 1000 microOhm sense (or shunt) resistor, in mA.
> > + * If a different shunt resistor is installed, calculate
> > + * the actual current by dividing the reported current
> > + * by the shunt resistor value in microOhms. The actual
> > + * The actual shunt resistor value can be specified
> > + * in the device tree.
>
> All but the last sentence just replace 1 mOhm with 1000 microOhm, which
> does not add any value. Applies to all similar changes; I won't comment
> on it anymore below.
>
> > */
> > - val *= 25;
> > + val *= 25 * 1000;
> > + val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> > break;
> > default:
> > return -EINVAL;
> > @@ -148,7 +163,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> > static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> > unsigned long val)
> > {
> > - struct regmap *regmap = dev_get_drvdata(dev);
> > + struct ltc2945_data *data = dev_get_drvdata(dev);
> > + struct regmap *regmap = data->regmap;
> > + u32 shunt_resistor = data->shunt_resistor;
> > unsigned int control;
> > int ret;
> >
> > @@ -160,8 +177,10 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> > case LTC2945_MIN_POWER_THRES_H:
> > /*
> > * Convert to register value by assuming current is measured
> > - * with an 1mOhm sense resistor, similar to current
> > + * with a 1000 microOhm sense resistor, (aka shunt resistor)
> > + * or what is specified in DT, similar to current
> > * measurements.
> > + *
> > * Control register bit 0 selects if voltage at SENSE+/VDD
> > * or voltage at ADIN is used to measure power, which in turn
> > * determines register calculations.
> > @@ -171,14 +190,16 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> > return ret;
> > if (control & CONTROL_MULT_SELECT) {
> > /* 25 mV * 25 uV = 0.625 uV resolution. */
> > - val = DIV_ROUND_CLOSEST(val, 625);
> > + val *= shunt_resistor;
>
> This can now easily result in an overflow.
Okay will fix
>
> > + val = DIV_ROUND_CLOSEST(val, 625 * 1000);
> > } else {
> > /*
> > * 0.5 mV * 25 uV = 0.0125 uV resolution.
> > * Divide first to avoid overflow;
> > * accept loss of accuracy.
> > */
> > - val = DIV_ROUND_CLOSEST(val, 25) * 2;
> > + val *= shunt_resistor;
> > + val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
> > }
> > break;
> > case LTC2945_VIN_H:
> > @@ -204,12 +225,14 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> > case LTC2945_MIN_SENSE_THRES_H:
> > /*
> > * 25 uV resolution. Convert to current as measured with
> > - * an 1 mOhm sense resistor, in mA. If a different sense
> > - * resistor is installed, calculate the actual current by
> > - * dividing the reported current by the sense resistor value
> > - * in mOhm.
> > + * a 1000 microOhm sense (or shunt) resistor, in mA. If
> > + * a different shunt resistor is installed, calculate
> > + * the actual current by dividing the reported current
> > + * by the sense resistor value in microOhms. The actual
> > + * shunt resistor value can be specified in the device tree.
> > */
> > - val = DIV_ROUND_CLOSEST(val, 25);
> > + val *= shunt_resistor;
>
> Needs to ensure that there are no overflows. Try to write the maximum value
> for unsigned long and see what happens.
>
> > + val = DIV_ROUND_CLOSEST(val, 25 * 1000);
> > break;
> > default:
> > return -EINVAL;
> > @@ -234,7 +257,8 @@ static ssize_t ltc2945_value_store(struct device *dev,
> > const char *buf, size_t count)
> > {
> > struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> > - struct regmap *regmap = dev_get_drvdata(dev);
> > + struct ltc2945_data *data = dev_get_drvdata(dev);
> > + struct regmap *regmap = data->regmap;
> > u8 reg = attr->index;
> > unsigned long val;
> > u8 regbuf[3];
> > @@ -269,7 +293,8 @@ static ssize_t ltc2945_history_store(struct device *dev,
> > const char *buf, size_t count)
> > {
> > struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> > - struct regmap *regmap = dev_get_drvdata(dev);
> > + struct ltc2945_data *data = dev_get_drvdata(dev);
> > + struct regmap *regmap = data->regmap; > u8 reg = attr->index;
> > int num_regs = is_power_reg(reg) ? 3 : 2;
> > u8 buf_min[3] = { 0xff, 0xff, 0xff };
> > @@ -321,7 +346,8 @@ static ssize_t ltc2945_bool_show(struct device *dev,
> > struct device_attribute *da, char *buf)
> > {
> > struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> > - struct regmap *regmap = dev_get_drvdata(dev);
> > + struct ltc2945_data *data = dev_get_drvdata(dev);
> > + struct regmap *regmap = data->regmap;
> > unsigned int fault;
> > int ret;
> >
> > @@ -450,6 +476,14 @@ static int ltc2945_probe(struct i2c_client *client)
> > struct device *dev = &client->dev;
> > struct device *hwmon_dev;
> > struct regmap *regmap;
> > + u32 shunt_resistor;
> > +
> drop this empty line
>
> > + struct ltc2945_data *data;
> > +
> > + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > + if (!data)
> > + return -ENOMEM;
> > + dev_set_drvdata(dev, data);
> >
> > regmap = devm_regmap_init_i2c(client, <c2945_regmap_config);
> > if (IS_ERR(regmap)) {
> > @@ -457,11 +491,21 @@ static int ltc2945_probe(struct i2c_client *client)
> > return PTR_ERR(regmap);
> > }
> >
> > + data->regmap = regmap;
> > + if (of_property_read_u32(client->dev.of_node,
> > + "shunt-resistor-micro-ohms", &shunt_resistor))
>
> Please consider using device_property_read_u32().
>
> > + shunt_resistor = 1000; /* 1000 micro-Ohm if not set via DT */
>
> "if not set via DT" -> "default value". With device_property_read_u32(),
> this can be set by other means, not just DT.
>
> > +
> > + if (shunt_resistor == 0)
> > + return -EINVAL;
> > +
> > + data->shunt_resistor = shunt_resistor;
> > +
> > /* Clear faults */
> > regmap_write(regmap, LTC2945_FAULT, 0x00);
> >
> > hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
> > - regmap,
> > + data,
> > ltc2945_groups);
> > return PTR_ERR_OR_ZERO(hwmon_dev);
> > }
>
--
Jonathan Cormier
Software Engineer
Voice: 315.425.4045 x222
http://www.CriticalLink.com
6712 Brooklawn Parkway, Syracuse, NY 13211
Added the ability to specify the value of the shunt resistor in the
device tree instead of assuming it is 1 milliOhm.
Would be good to backport as well
Changes since v1:
- Add devicetree match table
- Add kerneldoc for the ltc2945_data struct
- Cleanup excesive comments about the shunt resistor
- Switch to device_property_read_u32()
Cormier, Jonathan (1):
dt-bindings: hwmon: adi,ltc2945: Add binding
John Pruitt (1):
hwmon: ltc2945: Allow setting shunt resistor
.../bindings/hwmon/adi,ltc2945.yaml | 50 +++++++++++
drivers/hwmon/ltc2945.c | 86 ++++++++++++++-----
2 files changed, 115 insertions(+), 21 deletions(-)
create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
--
2.25.1
From: John Pruitt <[email protected]>
Use 64-bit values for intermediate calculations. Check for
overflows and return INT_MAX if overflows happened.
Signed-off-by: John Pruitt <[email protected]>
Signed-off-by: "Cormier, Jonathan" <[email protected]>
---
drivers/hwmon/ltc2945.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
index fc7d399b2c85..7239422fc6db 100644
--- a/drivers/hwmon/ltc2945.c
+++ b/drivers/hwmon/ltc2945.c
@@ -126,6 +126,10 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
}
val *= 1000;
val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
+ /* check for overflow, use MAX value if it happened */
+ if (val > INT_MAX)
+ val = INT_MAX;
+
break;
case LTC2945_VIN_H:
case LTC2945_MAX_VIN_H:
@@ -159,12 +163,14 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
}
static int ltc2945_val_to_reg(struct device *dev, u8 reg,
- unsigned long val)
+ unsigned long val_32)
{
struct ltc2945_data *data = dev_get_drvdata(dev);
struct regmap *regmap = data->regmap;
u32 shunt_resistor = data->shunt_resistor;
unsigned int control;
+ /* use 64-bit val for intermediate calculations */
+ unsigned long long val = val_32;
int ret;
switch (reg) {
@@ -184,7 +190,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
if (control & CONTROL_MULT_SELECT) {
/* 25 mV * 25 uV = 0.625 uV resolution. */
val *= shunt_resistor;
- val = DIV_ROUND_CLOSEST(val, 625 * 1000);
+ val = DIV_ROUND_CLOSEST_ULL(val, 625LL * 1000LL);
} else {
/*
* 0.5 mV * 25 uV = 0.0125 uV resolution.
@@ -192,7 +198,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
* accept loss of accuracy.
*/
val *= shunt_resistor;
- val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
+ val = DIV_ROUND_CLOSEST_ULL(val, 25LL * 1000LL) * 2;
}
break;
case LTC2945_VIN_H:
@@ -201,7 +207,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
case LTC2945_MAX_VIN_THRES_H:
case LTC2945_MIN_VIN_THRES_H:
/* 25 mV resolution. */
- val /= 25;
+ val = DIV_ROUND_CLOSEST_ULL(val, 25LL);
break;
case LTC2945_ADIN_H:
case LTC2945_MAX_ADIN_H:
@@ -218,11 +224,15 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
case LTC2945_MIN_SENSE_THRES_H:
/* 25 uV resolution. Convert to mA. */
val *= shunt_resistor;
- val = DIV_ROUND_CLOSEST(val, 25 * 1000);
+ val = DIV_ROUND_CLOSEST_ULL(val, 25LL * 1000LL);
break;
default:
return -EINVAL;
}
+ /* If val is too large, just return the max value */
+ if (val > INT_MAX)
+ return INT_MAX;
+
return val;
}
--
2.25.1
From: John Pruitt <[email protected]>
Added the ability to specify the value of the shunt resistor in the
device tree instead of assuming it is 1 milliOhm. The value in the
device tree has the name shunt-resistor-micro-ohms and the
default value is 1000 micro-ohms in order to preserve the
current behavior.
Signed-off-by: "Cormier, Jonathan" <[email protected]>
Signed-off-by: John Pruitt <[email protected]>
---
drivers/hwmon/ltc2945.c | 80 +++++++++++++++++++++++++----------------
1 file changed, 50 insertions(+), 30 deletions(-)
diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
index 9af3e3821152..fc7d399b2c85 100644
--- a/drivers/hwmon/ltc2945.c
+++ b/drivers/hwmon/ltc2945.c
@@ -64,6 +64,16 @@ static const struct of_device_id __maybe_unused ltc2945_of_match[] = {
};
MODULE_DEVICE_TABLE(of, ltc2945_of_match);
+/**
+ * struct ltc2945_data - LTC2945 device data
+ * @regmap: regmap device
+ * @shunt_resistor: shunt resistor value in micro ohms (1000 by default)
+ */
+struct ltc2945_data {
+ struct regmap *regmap;
+ u32 shunt_resistor;
+};
+
static inline bool is_power_reg(u8 reg)
{
return reg < LTC2945_SENSE_H;
@@ -72,7 +82,9 @@ static inline bool is_power_reg(u8 reg)
/* Return the value from the given register in uW, mV, or mA */
static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
{
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
+ u32 shunt_resistor = data->shunt_resistor;
unsigned int control;
u8 buf[3];
long long val;
@@ -98,9 +110,7 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
case LTC2945_MAX_POWER_THRES_H:
case LTC2945_MIN_POWER_THRES_H:
/*
- * Convert to uW by assuming current is measured with
- * an 1mOhm sense resistor, similar to current
- * measurements.
+ * Convert to uW
* Control register bit 0 selects if voltage at SENSE+/VDD
* or voltage at ADIN is used to measure power.
*/
@@ -114,6 +124,8 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
val = (val * 25LL) >> 1;
}
+ val *= 1000;
+ val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
break;
case LTC2945_VIN_H:
case LTC2945_MAX_VIN_H:
@@ -136,14 +148,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
case LTC2945_MIN_SENSE_H:
case LTC2945_MAX_SENSE_THRES_H:
case LTC2945_MIN_SENSE_THRES_H:
- /*
- * 25 uV resolution. Convert to current as measured with
- * an 1 mOhm sense resistor, in mA. If a different sense
- * resistor is installed, calculate the actual current by
- * dividing the reported current by the sense resistor value
- * in mOhm.
- */
- val *= 25;
+ /* 25 uV resolution. Convert to mA. */
+ val *= 25 * 1000;
+ val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
break;
default:
return -EINVAL;
@@ -154,7 +161,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
static int ltc2945_val_to_reg(struct device *dev, u8 reg,
unsigned long val)
{
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
+ u32 shunt_resistor = data->shunt_resistor;
unsigned int control;
int ret;
@@ -165,9 +174,6 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
case LTC2945_MAX_POWER_THRES_H:
case LTC2945_MIN_POWER_THRES_H:
/*
- * Convert to register value by assuming current is measured
- * with an 1mOhm sense resistor, similar to current
- * measurements.
* Control register bit 0 selects if voltage at SENSE+/VDD
* or voltage at ADIN is used to measure power, which in turn
* determines register calculations.
@@ -177,14 +183,16 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
return ret;
if (control & CONTROL_MULT_SELECT) {
/* 25 mV * 25 uV = 0.625 uV resolution. */
- val = DIV_ROUND_CLOSEST(val, 625);
+ val *= shunt_resistor;
+ val = DIV_ROUND_CLOSEST(val, 625 * 1000);
} else {
/*
* 0.5 mV * 25 uV = 0.0125 uV resolution.
* Divide first to avoid overflow;
* accept loss of accuracy.
*/
- val = DIV_ROUND_CLOSEST(val, 25) * 2;
+ val *= shunt_resistor;
+ val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
}
break;
case LTC2945_VIN_H:
@@ -208,14 +216,9 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
case LTC2945_MIN_SENSE_H:
case LTC2945_MAX_SENSE_THRES_H:
case LTC2945_MIN_SENSE_THRES_H:
- /*
- * 25 uV resolution. Convert to current as measured with
- * an 1 mOhm sense resistor, in mA. If a different sense
- * resistor is installed, calculate the actual current by
- * dividing the reported current by the sense resistor value
- * in mOhm.
- */
- val = DIV_ROUND_CLOSEST(val, 25);
+ /* 25 uV resolution. Convert to mA. */
+ val *= shunt_resistor;
+ val = DIV_ROUND_CLOSEST(val, 25 * 1000);
break;
default:
return -EINVAL;
@@ -240,7 +243,8 @@ static ssize_t ltc2945_value_store(struct device *dev,
const char *buf, size_t count)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
u8 reg = attr->index;
unsigned long val;
u8 regbuf[3];
@@ -275,7 +279,8 @@ static ssize_t ltc2945_history_store(struct device *dev,
const char *buf, size_t count)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
u8 reg = attr->index;
int num_regs = is_power_reg(reg) ? 3 : 2;
u8 buf_min[3] = { 0xff, 0xff, 0xff };
@@ -327,7 +332,8 @@ static ssize_t ltc2945_bool_show(struct device *dev,
struct device_attribute *da, char *buf)
{
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
- struct regmap *regmap = dev_get_drvdata(dev);
+ struct ltc2945_data *data = dev_get_drvdata(dev);
+ struct regmap *regmap = data->regmap;
unsigned int fault;
int ret;
@@ -456,6 +462,12 @@ static int ltc2945_probe(struct i2c_client *client)
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct regmap *regmap;
+ struct ltc2945_data *data;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+ dev_set_drvdata(dev, data);
regmap = devm_regmap_init_i2c(client, <c2945_regmap_config);
if (IS_ERR(regmap)) {
@@ -463,11 +475,19 @@ static int ltc2945_probe(struct i2c_client *client)
return PTR_ERR(regmap);
}
+ data->regmap = regmap;
+ if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
+ &data->shunt_resistor))
+ data->shunt_resistor = 1000;
+
+ if (data->shunt_resistor == 0)
+ return -EINVAL;
+
/* Clear faults */
regmap_write(regmap, LTC2945_FAULT, 0x00);
hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
- regmap,
+ data,
ltc2945_groups);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
--
2.25.1
Signed-off-by: "Cormier, Jonathan" <[email protected]>
---
drivers/hwmon/ltc2945.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
index 9adebb59f604..9af3e3821152 100644
--- a/drivers/hwmon/ltc2945.c
+++ b/drivers/hwmon/ltc2945.c
@@ -58,6 +58,12 @@
#define CONTROL_MULT_SELECT (1 << 0)
#define CONTROL_TEST_MODE (1 << 4)
+static const struct of_device_id __maybe_unused ltc2945_of_match[] = {
+ { .compatible = "adi,ltc2945" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ltc2945_of_match);
+
static inline bool is_power_reg(u8 reg)
{
return reg < LTC2945_SENSE_H;
@@ -475,8 +481,9 @@ MODULE_DEVICE_TABLE(i2c, ltc2945_id);
static struct i2c_driver ltc2945_driver = {
.driver = {
- .name = "ltc2945",
- },
+ .name = "ltc2945",
+ .of_match_table = of_match_ptr(ltc2945_of_match),
+ },
.probe_new = ltc2945_probe,
.id_table = ltc2945_id,
};
--
2.25.1
On Mon, Dec 19, 2022 at 07:04:55PM -0500, Cormier, Jonathan wrote:
> Signed-off-by: "Cormier, Jonathan" <[email protected]>
There should still be some description here.
> ---
> drivers/hwmon/ltc2945.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
> index 9adebb59f604..9af3e3821152 100644
> --- a/drivers/hwmon/ltc2945.c
> +++ b/drivers/hwmon/ltc2945.c
> @@ -58,6 +58,12 @@
> #define CONTROL_MULT_SELECT (1 << 0)
> #define CONTROL_TEST_MODE (1 << 4)
>
> +static const struct of_device_id __maybe_unused ltc2945_of_match[] = {
> + { .compatible = "adi,ltc2945" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, ltc2945_of_match);
> +
> static inline bool is_power_reg(u8 reg)
> {
> return reg < LTC2945_SENSE_H;
> @@ -475,8 +481,9 @@ MODULE_DEVICE_TABLE(i2c, ltc2945_id);
>
> static struct i2c_driver ltc2945_driver = {
> .driver = {
> - .name = "ltc2945",
> - },
> + .name = "ltc2945",
> + .of_match_table = of_match_ptr(ltc2945_of_match),
> + },
> .probe_new = ltc2945_probe,
> .id_table = ltc2945_id,
> };
> --
> 2.25.1
On Mon, Dec 19, 2022 at 07:04:56PM -0500, Cormier, Jonathan wrote:
> From: John Pruitt <[email protected]>
>
> Added the ability to specify the value of the shunt resistor in the
a/Added/Add/
Per Documentation/process/submitting-patches.rst:
"
Describe your changes in imperative mood, e.g. "make xyzzy do frotz"
instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy
to do frotz", as if you are giving orders to the codebase to change
its behaviour.
"
> device tree instead of assuming it is 1 milliOhm. The value in the
> device tree has the name shunt-resistor-micro-ohms and the
> default value is 1000 micro-ohms in order to preserve the
> current behavior.
>
> Signed-off-by: "Cormier, Jonathan" <[email protected]>
> Signed-off-by: John Pruitt <[email protected]>
> ---
> drivers/hwmon/ltc2945.c | 80 +++++++++++++++++++++++++----------------
> 1 file changed, 50 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
> index 9af3e3821152..fc7d399b2c85 100644
> --- a/drivers/hwmon/ltc2945.c
> +++ b/drivers/hwmon/ltc2945.c
> @@ -64,6 +64,16 @@ static const struct of_device_id __maybe_unused ltc2945_of_match[] = {
> };
> MODULE_DEVICE_TABLE(of, ltc2945_of_match);
>
> +/**
> + * struct ltc2945_data - LTC2945 device data
> + * @regmap: regmap device
> + * @shunt_resistor: shunt resistor value in micro ohms (1000 by default)
> + */
> +struct ltc2945_data {
> + struct regmap *regmap;
> + u32 shunt_resistor;
> +};
> +
> static inline bool is_power_reg(u8 reg)
> {
> return reg < LTC2945_SENSE_H;
> @@ -72,7 +82,9 @@ static inline bool is_power_reg(u8 reg)
> /* Return the value from the given register in uW, mV, or mA */
> static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> {
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> + u32 shunt_resistor = data->shunt_resistor;
> unsigned int control;
> u8 buf[3];
> long long val;
> @@ -98,9 +110,7 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> case LTC2945_MAX_POWER_THRES_H:
> case LTC2945_MIN_POWER_THRES_H:
> /*
> - * Convert to uW by assuming current is measured with
> - * an 1mOhm sense resistor, similar to current
> - * measurements.
> + * Convert to uW
> * Control register bit 0 selects if voltage at SENSE+/VDD
> * or voltage at ADIN is used to measure power.
> */
> @@ -114,6 +124,8 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> /* 0.5 mV * 25 uV = 0.0125 uV resolution. */
> val = (val * 25LL) >> 1;
> }
> + val *= 1000;
> + val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> break;
> case LTC2945_VIN_H:
> case LTC2945_MAX_VIN_H:
> @@ -136,14 +148,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> case LTC2945_MIN_SENSE_H:
> case LTC2945_MAX_SENSE_THRES_H:
> case LTC2945_MIN_SENSE_THRES_H:
> - /*
> - * 25 uV resolution. Convert to current as measured with
> - * an 1 mOhm sense resistor, in mA. If a different sense
> - * resistor is installed, calculate the actual current by
> - * dividing the reported current by the sense resistor value
> - * in mOhm.
> - */
> - val *= 25;
> + /* 25 uV resolution. Convert to mA. */
> + val *= 25 * 1000;
> + val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> break;
> default:
> return -EINVAL;
> @@ -154,7 +161,9 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> unsigned long val)
> {
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> + u32 shunt_resistor = data->shunt_resistor;
> unsigned int control;
> int ret;
>
> @@ -165,9 +174,6 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> case LTC2945_MAX_POWER_THRES_H:
> case LTC2945_MIN_POWER_THRES_H:
> /*
> - * Convert to register value by assuming current is measured
> - * with an 1mOhm sense resistor, similar to current
> - * measurements.
> * Control register bit 0 selects if voltage at SENSE+/VDD
> * or voltage at ADIN is used to measure power, which in turn
> * determines register calculations.
> @@ -177,14 +183,16 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> return ret;
> if (control & CONTROL_MULT_SELECT) {
> /* 25 mV * 25 uV = 0.625 uV resolution. */
> - val = DIV_ROUND_CLOSEST(val, 625);
> + val *= shunt_resistor;
> + val = DIV_ROUND_CLOSEST(val, 625 * 1000);
Overflows are introduced and need to be be handled in this patch.
It doesn't make sense to introduce them and fix them in the next patch.
> } else {
> /*
> * 0.5 mV * 25 uV = 0.0125 uV resolution.
> * Divide first to avoid overflow;
> * accept loss of accuracy.
> */
> - val = DIV_ROUND_CLOSEST(val, 25) * 2;
> + val *= shunt_resistor;
> + val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
> }
> break;
> case LTC2945_VIN_H:
> @@ -208,14 +216,9 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> case LTC2945_MIN_SENSE_H:
> case LTC2945_MAX_SENSE_THRES_H:
> case LTC2945_MIN_SENSE_THRES_H:
> - /*
> - * 25 uV resolution. Convert to current as measured with
> - * an 1 mOhm sense resistor, in mA. If a different sense
> - * resistor is installed, calculate the actual current by
> - * dividing the reported current by the sense resistor value
> - * in mOhm.
> - */
> - val = DIV_ROUND_CLOSEST(val, 25);
> + /* 25 uV resolution. Convert to mA. */
> + val *= shunt_resistor;
> + val = DIV_ROUND_CLOSEST(val, 25 * 1000);
> break;
> default:
> return -EINVAL;
> @@ -240,7 +243,8 @@ static ssize_t ltc2945_value_store(struct device *dev,
> const char *buf, size_t count)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> u8 reg = attr->index;
> unsigned long val;
> u8 regbuf[3];
> @@ -275,7 +279,8 @@ static ssize_t ltc2945_history_store(struct device *dev,
> const char *buf, size_t count)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> u8 reg = attr->index;
> int num_regs = is_power_reg(reg) ? 3 : 2;
> u8 buf_min[3] = { 0xff, 0xff, 0xff };
> @@ -327,7 +332,8 @@ static ssize_t ltc2945_bool_show(struct device *dev,
> struct device_attribute *da, char *buf)
> {
> struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
> - struct regmap *regmap = dev_get_drvdata(dev);
> + struct ltc2945_data *data = dev_get_drvdata(dev);
> + struct regmap *regmap = data->regmap;
> unsigned int fault;
> int ret;
>
> @@ -456,6 +462,12 @@ static int ltc2945_probe(struct i2c_client *client)
> struct device *dev = &client->dev;
> struct device *hwmon_dev;
> struct regmap *regmap;
> + struct ltc2945_data *data;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> + dev_set_drvdata(dev, data);
>
> regmap = devm_regmap_init_i2c(client, <c2945_regmap_config);
> if (IS_ERR(regmap)) {
> @@ -463,11 +475,19 @@ static int ltc2945_probe(struct i2c_client *client)
> return PTR_ERR(regmap);
> }
>
> + data->regmap = regmap;
> + if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
> + &data->shunt_resistor))
> + data->shunt_resistor = 1000;
> +
> + if (data->shunt_resistor == 0)
> + return -EINVAL;
> +
> /* Clear faults */
> regmap_write(regmap, LTC2945_FAULT, 0x00);
>
> hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
> - regmap,
> + data,
> ltc2945_groups);
> return PTR_ERR_OR_ZERO(hwmon_dev);
> }
> --
> 2.25.1
On Mon, Dec 19, 2022 at 07:04:57PM -0500, Cormier, Jonathan wrote:
> From: John Pruitt <[email protected]>
>
> Use 64-bit values for intermediate calculations. Check for
> overflows and return INT_MAX if overflows happened.
>
> Signed-off-by: John Pruitt <[email protected]>
> Signed-off-by: "Cormier, Jonathan" <[email protected]>
The problems here are introduced with the previous patch
and thus would need a Fixes: tag. It just doesn't make sense
to submit that as separate patch.
> ---
> drivers/hwmon/ltc2945.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
> index fc7d399b2c85..7239422fc6db 100644
> --- a/drivers/hwmon/ltc2945.c
> +++ b/drivers/hwmon/ltc2945.c
> @@ -126,6 +126,10 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> }
> val *= 1000;
> val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
> + /* check for overflow, use MAX value if it happened */
> + if (val > INT_MAX)
> + val = INT_MAX;
> +
ltc2945_reg_to_val returns long long, and the calling code expects long long.
How would this ever overflow ?
> break;
> case LTC2945_VIN_H:
> case LTC2945_MAX_VIN_H:
> @@ -159,12 +163,14 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> }
>
> static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> - unsigned long val)
> + unsigned long val_32)
> {
> struct ltc2945_data *data = dev_get_drvdata(dev);
> struct regmap *regmap = data->regmap;
> u32 shunt_resistor = data->shunt_resistor;
> unsigned int control;
> + /* use 64-bit val for intermediate calculations */
> + unsigned long long val = val_32;
This is unnnecessary. The parameter can be unsigned long long,
making the conversion automatic.
> int ret;
>
> switch (reg) {
> @@ -184,7 +190,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> if (control & CONTROL_MULT_SELECT) {
> /* 25 mV * 25 uV = 0.625 uV resolution. */
> val *= shunt_resistor;
> - val = DIV_ROUND_CLOSEST(val, 625 * 1000);
> + val = DIV_ROUND_CLOSEST_ULL(val, 625LL * 1000LL);
> } else {
> /*
> * 0.5 mV * 25 uV = 0.0125 uV resolution.
> @@ -192,7 +198,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> * accept loss of accuracy.
> */
> val *= shunt_resistor;
> - val = DIV_ROUND_CLOSEST(val, 25 * 1000) * 2;
> + val = DIV_ROUND_CLOSEST_ULL(val, 25LL * 1000LL) * 2;
> }
> break;
> case LTC2945_VIN_H:
> @@ -201,7 +207,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> case LTC2945_MAX_VIN_THRES_H:
> case LTC2945_MIN_VIN_THRES_H:
> /* 25 mV resolution. */
> - val /= 25;
> + val = DIV_ROUND_CLOSEST_ULL(val, 25LL);
Unrelated change causing behavioral change. Not that I mind, but it is
still unrelated and would have to be a separate patch.
> break;
> case LTC2945_ADIN_H:
> case LTC2945_MAX_ADIN_H:
> @@ -218,11 +224,15 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> case LTC2945_MIN_SENSE_THRES_H:
> /* 25 uV resolution. Convert to mA. */
> val *= shunt_resistor;
> - val = DIV_ROUND_CLOSEST(val, 25 * 1000);
> + val = DIV_ROUND_CLOSEST_ULL(val, 25LL * 1000LL);
> break;
> default:
> return -EINVAL;
> }
> + /* If val is too large, just return the max value */
> + if (val > INT_MAX)
> + return INT_MAX;
> +
While the return value is declared as int, the calling code expects
unsigned long. It would be better to adjust the return value and clamp
against ULONG_MAX.
> return val;
> }
>
> --
> 2.25.1
Added the ability to specify the value of the shunt resistor in the
device tree instead of assuming it is 1 milliOhm.
Would be good to backport as well
Changes since v2:
- Remove newline
- Combined overflow fix with "Allow setting shunt resistor" commit
- Add description to "Add devicetree match table"
- Add fix for unhandled error case in ltc2945_value_store
- Use imperative in descriptions
- Remove unneeded overflow check from ltc2945_reg_to_val
- Fix up DIV_ROUND_CLOSEST_ULL calls, per docs divisor should be 32-bit
- Split one DIV_ROUND_CLOSEST_ULL change into separate commit per
Guenter Roeck's comment
Changes since v1:
- Add devicetree match table
- Add kerneldoc for the ltc2945_data struct
- Cleanup excesive comments about the shunt resistor
- Switch to device_property_read_u32()
Cormier, Jonathan (1):
dt-bindings: hwmon: adi,ltc2945: Add binding
John Pruitt (1):
hwmon: ltc2945: Allow setting shunt resistor
.../bindings/hwmon/adi,ltc2945.yaml | 50 +++++++++++
drivers/hwmon/ltc2945.c | 86 ++++++++++++++-----
2 files changed, 115 insertions(+), 21 deletions(-)
create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
--
2.25.1
Create initial binding for the LTC2945 I2C power monitor.
Add shunt-resistor-micro-ohms parameter
Signed-off-by: Jonathan Cormier <[email protected]>
---
.../bindings/hwmon/adi,ltc2945.yaml | 49 +++++++++++++++++++
1 file changed, 49 insertions(+)
create mode 100644 Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
diff --git a/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
new file mode 100644
index 000000000000..5cb66e97e816
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/adi,ltc2945.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/adi,ltc2945.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices LTC2945 wide range i2c power monitor
+
+maintainers:
+ - Guenter Roeck <[email protected]>
+
+description: |
+ Analog Devices LTC2945 wide range i2c power monitor over I2C.
+
+ https://www.analog.com/media/en/technical-documentation/data-sheets/LTC2945.pdf
+
+properties:
+ compatible:
+ enum:
+ - adi,ltc2945
+
+ reg:
+ maxItems: 1
+
+ shunt-resistor-micro-ohms:
+ description:
+ Shunt resistor value in micro-Ohms
+ default: 1000
+
+required:
+ - compatible
+ - reg
+
+additionalProperties: false
+
+examples:
+ - |
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ power-monitor@6e {
+ compatible = "adi,ltc2945";
+ reg = <0x6e>;
+ /* 10 milli-Ohm shunt resistor */
+ shunt-resistor-micro-ohms = <10000>;
+ };
+ };
+...
--
2.25.1
On 10/01/2023 00:35, Jonathan Cormier wrote:
> Create initial binding for the LTC2945 I2C power monitor.
> Add shunt-resistor-micro-ohms parameter
If you want to keep that sentence, sure, but let's make it a sentence -
missing full stop.
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Best regards,
Krzysztof