Messages in this thread | | | Date | Wed, 10 Dec 2014 06:20:31 -0800 | From | Guenter Roeck <> | Subject | Re: [PATCH v5 1/3] hwmon: ina2xx: make shunt resistance configurable at run-time |
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On 12/10/2014 02:38 AM, Bartosz Golaszewski wrote: > The shunt resistance can only be set via platform_data or device tree. This > isn't suitable for devices in which the shunt resistance can change/isn't > known at boot-time. > > Add a sysfs attribute that allows to read and set the shunt resistance. > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > --- > drivers/hwmon/ina2xx.c | 74 ++++++++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 65 insertions(+), 9 deletions(-) > > diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c > index e01feba..6e73add 100644 > --- a/drivers/hwmon/ina2xx.c > +++ b/drivers/hwmon/ina2xx.c > @@ -51,7 +51,6 @@ > #define INA226_ALERT_LIMIT 0x07 > #define INA226_DIE_ID 0xFF > > -
While nice, this is an unrelated change.
> /* register count */ > #define INA219_REGISTERS 6 > #define INA226_REGISTERS 8 > @@ -65,6 +64,9 @@ > /* worst case is 68.10 ms (~14.6Hz, ina219) */ > #define INA2XX_CONVERSION_RATE 15 > > +/* default shunt resistance */ > +#define INA2XX_RSHUNT_DEFAULT 10000 > + > enum ina2xx_ids { ina219, ina226 }; > > struct ina2xx_config { > @@ -87,6 +89,8 @@ struct ina2xx_data { > > int kind; > u16 regs[INA2XX_MAX_REGISTERS]; > + > + long rshunt; > }; > > static const struct ina2xx_config ina2xx_config[] = { > @@ -110,6 +114,11 @@ static const struct ina2xx_config ina2xx_config[] = { > }, > }; > > +static u16 ina2xx_calibration_val(const struct ina2xx_data *data) > +{ > + return data->config->calibration_factor / data->rshunt; > +} > + > static struct ina2xx_data *ina2xx_update_device(struct device *dev) > { > struct ina2xx_data *data = dev_get_drvdata(dev); > @@ -164,6 +173,13 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg) > /* signed register, LSB=1mA (selected), in mA */ > val = (s16)data->regs[reg]; > break; > + case INA2XX_CALIBRATION: > + if (data->regs[reg] == 0) > + val = 0; > + else > + val = data->config->calibration_factor > + / data->regs[reg]; > + break;
This doesn't really make sense. What you want to show is rshunt, not the above. I think it would be better to write a separate show function to display it.
> default: > /* programmer goofed */ > WARN_ON_ONCE(1); > @@ -187,6 +203,38 @@ static ssize_t ina2xx_show_value(struct device *dev, > ina2xx_get_value(data, attr->index)); > } > > +static ssize_t ina2xx_set_shunt(struct device *dev, > + struct device_attribute *da, > + const char *buf, size_t count) > +{ > + struct ina2xx_data *data = ina2xx_update_device(dev); > + unsigned long val; > + int status; > + > + if (IS_ERR(data)) > + return PTR_ERR(data); > + > + status = kstrtoul(buf, 10, &val); > + if (status < 0) > + return status; > + > + if (val == 0 || > + /* Values greater than the calibration factor make no sense. */ > + val > data->config->calibration_factor || > + val > LONG_MAX)
data->config->calibration_factor is <= LONG_MAX, so the second check is unnecessary. Actually, given that calibration_factor is chip dependent and not necessarily known by the user, it would make more sense to only bail out on == 0 and then use clamp_val to limit the range to (1, data->config->calibration_factor).
Guenter
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