* [PATCH v3 1/2] hwmon: (adm1275): Allow setting shunt reg value @ 2018-10-17 22:26 Kun Yi [not found] ` <20181027172833.GA25052@roeck-us.net> 0 siblings, 1 reply; 2+ messages in thread From: Kun Yi @ 2018-10-17 22:26 UTC (permalink / raw) Cc: openbmc, kunyi, Guenter Roeck, Jean Delvare, Jonathan Corbet, linux-hwmon, linux-doc, linux-kernel 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 parses device tree parameter "shunt-resistor-micro-ohms", if there is one. Signed-off-by: Kun Yi <kunyi@google.com> --- Changes in v3: - splitted hwmon and device tree binding patches Documentation/hwmon/adm1275 | 3 +++ drivers/hwmon/pmbus/adm1275.c | 15 +++++++++++++-- 2 files changed, 16 insertions(+), 2 deletions(-) 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; } -- 2.19.1.331.ge82ca0e54c-goog ^ permalink raw reply related [flat|nested] 2+ messages in thread
[parent not found: <20181027172833.GA25052@roeck-us.net>]
* Re: [PATCH v3 1/2] hwmon: (adm1275): Allow setting shunt reg value [not found] ` <20181027172833.GA25052@roeck-us.net> @ 2018-10-29 20:21 ` Kun Yi 0 siblings, 0 replies; 2+ messages in thread From: Kun Yi @ 2018-10-29 20:21 UTC (permalink / raw) To: Guenter Roeck Cc: OpenBMC Maillist, jdelvare, corbet, linux-hwmon, linux-doc, linux-kernel On Sat, Oct 27, 2018 at 10:28 AM Guenter Roeck <linux@roeck-us.net> wrote: > > On Wed, Oct 17, 2018 at 03:26:39PM -0700, Kun Yi wrote: > > 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 parses device tree parameter > > "shunt-resistor-micro-ohms", if there is one. > > > > Signed-off-by: Kun Yi <kunyi@google.com> > > Applied to hwmon-next. > > Thanks, > Guenter > > > --- > > Changes in v3: > > - splitted hwmon and device tree binding patches > > > > Documentation/hwmon/adm1275 | 3 +++ > > drivers/hwmon/pmbus/adm1275.c | 15 +++++++++++++-- > > 2 files changed, 16 insertions(+), 2 deletions(-) > > > > 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; > > } Thanks! -- Regards, Kun ^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2018-10-29 20:21 UTC | newest] Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2018-10-17 22:26 [PATCH v3 1/2] hwmon: (adm1275): Allow setting shunt reg value Kun Yi [not found] ` <20181027172833.GA25052@roeck-us.net> 2018-10-29 20:21 ` Kun Yi
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