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https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
hwmon: (ltc2945) Allow setting shunt resistor
Add 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: Jonathan Cormier <jcormier@criticallink.com> Signed-off-by: John Pruitt <jpruitt@criticallink.com> [groeck: Fixed multi-line alignment, squashed last patch of series] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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178b01eccf
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b11f3d47c0
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@ -64,6 +64,16 @@ static const struct of_device_id __maybe_unused ltc2945_of_match[] = {
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};
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MODULE_DEVICE_TABLE(of, ltc2945_of_match);
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/**
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* struct ltc2945_data - LTC2945 device data
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* @regmap: regmap device
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* @shunt_resistor: shunt resistor value in micro ohms (1000 by default)
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*/
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struct ltc2945_data {
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struct regmap *regmap;
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u32 shunt_resistor;
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};
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static inline bool is_power_reg(u8 reg)
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{
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return reg < LTC2945_SENSE_H;
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@ -72,7 +82,9 @@ static inline bool is_power_reg(u8 reg)
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/* Return the value from the given register in uW, mV, or mA */
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static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
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{
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struct regmap *regmap = dev_get_drvdata(dev);
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struct ltc2945_data *data = dev_get_drvdata(dev);
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struct regmap *regmap = data->regmap;
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u32 shunt_resistor = data->shunt_resistor;
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unsigned int control;
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u8 buf[3];
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long long val;
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@ -84,10 +96,10 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
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return ret;
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if (is_power_reg(reg)) {
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/* power */
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/* 24-bit power */
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val = (buf[0] << 16) + (buf[1] << 8) + buf[2];
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} else {
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/* current, voltage */
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/* 12-bit current, voltage */
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val = (buf[0] << 4) + (buf[1] >> 4);
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}
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@ -98,9 +110,7 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
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case LTC2945_MAX_POWER_THRES_H:
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case LTC2945_MIN_POWER_THRES_H:
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/*
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* Convert to uW by assuming current is measured with
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* an 1mOhm sense resistor, similar to current
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* measurements.
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* Convert to uW
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* Control register bit 0 selects if voltage at SENSE+/VDD
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* or voltage at ADIN is used to measure power.
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*/
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@ -114,6 +124,14 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
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/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
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val = (val * 25LL) >> 1;
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}
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val *= 1000;
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/* Overflow check: Assuming max 24-bit power, val is at most 53 bits right now. */
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val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
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/*
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* Overflow check: After division, depending on shunt resistor,
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* val can still be > 32 bits so returning long long makes sense
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*/
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break;
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case LTC2945_VIN_H:
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case LTC2945_MAX_VIN_H:
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@ -136,14 +154,11 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
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case LTC2945_MIN_SENSE_H:
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case LTC2945_MAX_SENSE_THRES_H:
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case LTC2945_MIN_SENSE_THRES_H:
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/*
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* 25 uV resolution. Convert to current as measured with
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* an 1 mOhm sense resistor, in mA. If a different sense
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* resistor is installed, calculate the actual current by
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* dividing the reported current by the sense resistor value
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* in mOhm.
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*/
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val *= 25;
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/* 25 uV resolution. Convert to mA. */
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val *= 25 * 1000;
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/* Overflow check: Assuming max 12-bit sense, val is at most 27 bits right now */
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val = DIV_ROUND_CLOSEST_ULL(val, shunt_resistor);
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/* Overflow check: After division, <= 27 bits */
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break;
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default:
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return -EINVAL;
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@ -151,13 +166,18 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
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return val;
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}
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static int ltc2945_val_to_reg(struct device *dev, u8 reg,
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unsigned long val)
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static long long ltc2945_val_to_reg(struct device *dev, u8 reg,
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unsigned long long val)
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{
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struct regmap *regmap = dev_get_drvdata(dev);
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struct ltc2945_data *data = dev_get_drvdata(dev);
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struct regmap *regmap = data->regmap;
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u32 shunt_resistor = data->shunt_resistor;
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unsigned int control;
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int ret;
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/* Ensure we don't overflow */
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val = clamp_val(val, 0, U32_MAX);
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switch (reg) {
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case LTC2945_POWER_H:
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case LTC2945_MAX_POWER_H:
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@ -165,9 +185,6 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
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case LTC2945_MAX_POWER_THRES_H:
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case LTC2945_MIN_POWER_THRES_H:
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/*
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* Convert to register value by assuming current is measured
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* with an 1mOhm sense resistor, similar to current
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* measurements.
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* Control register bit 0 selects if voltage at SENSE+/VDD
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* or voltage at ADIN is used to measure power, which in turn
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* determines register calculations.
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@ -177,14 +194,16 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
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return ret;
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if (control & CONTROL_MULT_SELECT) {
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/* 25 mV * 25 uV = 0.625 uV resolution. */
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val = DIV_ROUND_CLOSEST(val, 625);
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val *= shunt_resistor;
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/* Overflow check: Assuming 32-bit val and shunt resistor, val <= 64bits */
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val = DIV_ROUND_CLOSEST_ULL(val, 625 * 1000);
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/* Overflow check: val is now <= 44 bits */
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} else {
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/*
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* 0.5 mV * 25 uV = 0.0125 uV resolution.
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* Divide first to avoid overflow;
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* accept loss of accuracy.
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*/
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val = DIV_ROUND_CLOSEST(val, 25) * 2;
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/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
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val *= shunt_resistor;
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/* Overflow check: Assuming 32-bit val and shunt resistor, val <= 64bits */
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val = DIV_ROUND_CLOSEST_ULL(val, 25 * 1000) * 2;
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/* Overflow check: val is now <= 51 bits */
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}
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break;
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case LTC2945_VIN_H:
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@ -193,7 +212,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
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case LTC2945_MAX_VIN_THRES_H:
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case LTC2945_MIN_VIN_THRES_H:
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/* 25 mV resolution. */
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val /= 25;
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val = DIV_ROUND_CLOSEST_ULL(val, 25);
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break;
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case LTC2945_ADIN_H:
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case LTC2945_MAX_ADIN_H:
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@ -208,14 +227,11 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
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case LTC2945_MIN_SENSE_H:
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case LTC2945_MAX_SENSE_THRES_H:
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case LTC2945_MIN_SENSE_THRES_H:
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/*
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* 25 uV resolution. Convert to current as measured with
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* an 1 mOhm sense resistor, in mA. If a different sense
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* resistor is installed, calculate the actual current by
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* dividing the reported current by the sense resistor value
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* in mOhm.
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*/
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val = DIV_ROUND_CLOSEST(val, 25);
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/* 25 uV resolution. Convert to mA. */
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val *= shunt_resistor;
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/* Overflow check: Assuming 32-bit val and 32-bit shunt resistor, val is 64bits */
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val = DIV_ROUND_CLOSEST_ULL(val, 25 * 1000);
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/* Overflow check: val is now <= 50 bits */
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break;
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default:
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return -EINVAL;
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@ -240,15 +256,16 @@ static ssize_t ltc2945_value_store(struct device *dev,
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const char *buf, size_t count)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct regmap *regmap = dev_get_drvdata(dev);
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struct ltc2945_data *data = dev_get_drvdata(dev);
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struct regmap *regmap = data->regmap;
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u8 reg = attr->index;
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unsigned long val;
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unsigned int val;
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u8 regbuf[3];
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int num_regs;
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int regval;
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long long regval;
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int ret;
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ret = kstrtoul(buf, 10, &val);
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ret = kstrtouint(buf, 10, &val);
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if (ret)
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return ret;
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@ -277,7 +294,8 @@ static ssize_t ltc2945_history_store(struct device *dev,
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const char *buf, size_t count)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct regmap *regmap = dev_get_drvdata(dev);
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struct ltc2945_data *data = dev_get_drvdata(dev);
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struct regmap *regmap = data->regmap;
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u8 reg = attr->index;
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int num_regs = is_power_reg(reg) ? 3 : 2;
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u8 buf_min[3] = { 0xff, 0xff, 0xff };
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@ -329,7 +347,8 @@ static ssize_t ltc2945_bool_show(struct device *dev,
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struct device_attribute *da, char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct regmap *regmap = dev_get_drvdata(dev);
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struct ltc2945_data *data = dev_get_drvdata(dev);
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struct regmap *regmap = data->regmap;
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unsigned int fault;
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int ret;
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@ -458,6 +477,12 @@ static int ltc2945_probe(struct i2c_client *client)
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struct device *dev = &client->dev;
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struct device *hwmon_dev;
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struct regmap *regmap;
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struct ltc2945_data *data;
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data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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dev_set_drvdata(dev, data);
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regmap = devm_regmap_init_i2c(client, <c2945_regmap_config);
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if (IS_ERR(regmap)) {
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@ -465,11 +490,19 @@ static int ltc2945_probe(struct i2c_client *client)
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return PTR_ERR(regmap);
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}
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data->regmap = regmap;
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if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
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&data->shunt_resistor))
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data->shunt_resistor = 1000;
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if (data->shunt_resistor == 0)
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return -EINVAL;
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/* Clear faults */
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regmap_write(regmap, LTC2945_FAULT, 0x00);
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
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regmap,
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data,
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ltc2945_groups);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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