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[72.90.70.109]) by smtp.gmail.com with ESMTPSA id l24-20020ae9f018000000b006fc2b672950sm10623939qkg.37.2022.12.14.14.07.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Dec 2022 14:07:42 -0800 (PST) From: "Cormier, Jonathan" To: linux-hwmon@vger.kernel.org Cc: John Pruitt , Jean Delvare , Guenter Roeck , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Bob Duke , "Cormier, Jonathan" Subject: [PATCH 2/2] hwmon: ltc2945: Allow setting shunt resistor Date: Wed, 14 Dec 2022 17:07:27 -0500 Message-Id: <20221214220727.1350784-3-jcormier@criticallink.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221214220727.1350784-1-jcormier@criticallink.com> References: <20221214220727.1350784-1-jcormier@criticallink.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1752229002631218550?= X-GMAIL-MSGID: =?utf-8?q?1752229002631218550?= From: John Pruitt 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" Signed-off-by: John Pruitt --- 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); }