The ADM series of hotswap controllers support extending the current measurement range by using a sensing resistor value other than the typical 1 mOhm. For example, using a 0.5 mOhm sensing resistor doubles the maximal current can be measured.
Current driver assumes a shunt resistor value of 1 mOhm in calculation, meaning for other resistor values, hwmon will report scaled current/power measurements. This patch adds a device tree parameter so that individual boards can configure its shunt resistor value. Signed-off-by: Kun Yi <[email protected]> --- .../devicetree/bindings/hwmon/adm1275.txt | 25 +++++++++++++++++++ Documentation/hwmon/adm1275 | 3 +++ drivers/hwmon/pmbus/adm1275.c | 15 +++++++++-- 3 files changed, 41 insertions(+), 2 deletions(-) create mode 100644 Documentation/devicetree/bindings/hwmon/adm1275.txt diff --git a/Documentation/devicetree/bindings/hwmon/adm1275.txt b/Documentation/devicetree/bindings/hwmon/adm1275.txt new file mode 100644 index 000000000000..1ecd03f3da4d --- /dev/null +++ b/Documentation/devicetree/bindings/hwmon/adm1275.txt @@ -0,0 +1,25 @@ +adm1275 properties + +Required properties: +- compatible: Must be one of the supported compatible strings: + - "adi,adm1075" for adm1075 + - "adi,adm1272" for adm1272 + - "adi,adm1275" for adm1275 + - "adi,adm1276" for adm1276 + - "adi,adm1278" for adm1278 + - "adi,adm1293" for adm1293 + - "adi,adm1294" for adm1294 +- reg: I2C address + +Optional properties: + +- shunt-resistor-micro-ohms + Shunt resistor value in micro-Ohm + +Example: + +adm1272@10 { + compatible = "adi,adm1272"; + reg = <0x10>; + shunt-resistor-micro-ohms = <500>; +}; diff --git a/Documentation/hwmon/adm1275 b/Documentation/hwmon/adm1275 index 39033538eb03..5e277b0d91ce 100644 --- a/Documentation/hwmon/adm1275 +++ b/Documentation/hwmon/adm1275 @@ -58,6 +58,9 @@ The ADM1075, unlike many other PMBus devices, does not support internal voltage or current scaling. Reported voltages, currents, and power are raw measurements, and will typically have to be scaled. +The shunt value in micro-ohms can be set via device tree at compile-time. Please +refer to the Documentation/devicetree/bindings/hwmon/adm1275.txt for bindings +if the device tree is used. Platform data support --------------------- diff --git a/drivers/hwmon/pmbus/adm1275.c b/drivers/hwmon/pmbus/adm1275.c index 13600fa79e7f..f569372c9204 100644 --- a/drivers/hwmon/pmbus/adm1275.c +++ b/drivers/hwmon/pmbus/adm1275.c @@ -373,6 +373,7 @@ static int adm1275_probe(struct i2c_client *client, const struct coefficients *coefficients; int vindex = -1, voindex = -1, cindex = -1, pindex = -1; int tindex = -1; + u32 shunt; if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA @@ -421,6 +422,13 @@ static int adm1275_probe(struct i2c_client *client, if (!data) return -ENOMEM; + if (of_property_read_u32(client->dev.of_node, + "shunt-resistor-micro-ohms", &shunt)) + shunt = 1000; /* 1 mOhm if not set via DT */ + + if (shunt == 0) + return -EINVAL; + data->id = mid->driver_data; info = &data->info; @@ -654,12 +662,15 @@ static int adm1275_probe(struct i2c_client *client, info->R[PSC_VOLTAGE_OUT] = coefficients[voindex].R; } if (cindex >= 0) { - info->m[PSC_CURRENT_OUT] = coefficients[cindex].m; + /* Scale current with sense resistor value */ + info->m[PSC_CURRENT_OUT] = + coefficients[cindex].m * shunt / 1000; info->b[PSC_CURRENT_OUT] = coefficients[cindex].b; info->R[PSC_CURRENT_OUT] = coefficients[cindex].R; } if (pindex >= 0) { - info->m[PSC_POWER] = coefficients[pindex].m; + info->m[PSC_POWER] = + coefficients[pindex].m * shunt / 1000; info->b[PSC_POWER] = coefficients[pindex].b; info->R[PSC_POWER] = coefficients[pindex].R; } -- 2.19.0.605.g01d371f741-goog
