From 30fe976fe7a8de2d29c152cdcae207231503d564 Mon Sep 17 00:00:00 2001 From: Daniel Golle Date: Mon, 1 Aug 2016 12:07:18 +0200 Subject: [PATCH] hwmon: (ltc4151) Make shunt-resistor configurable Allow to specify the resistance of the attached shunt via DT by adding the shunt-resistor property. Fall-back to the previous default (1 mOhm) if unset. Signed-off-by: Daniel Golle [groeck: Fixed 'line over 80 columns' checkpatch warning] Signed-off-by: Guenter Roeck --- drivers/hwmon/ltc4151.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/drivers/hwmon/ltc4151.c b/drivers/hwmon/ltc4151.c index c86a18402496..8445c9fd946b 100644 --- a/drivers/hwmon/ltc4151.c +++ b/drivers/hwmon/ltc4151.c @@ -30,6 +30,7 @@ #include #include +#include #include #include #include @@ -52,6 +53,7 @@ struct ltc4151_data { struct mutex update_lock; bool valid; unsigned long last_updated; /* in jiffies */ + unsigned int shunt; /* in micro ohms */ /* Registers */ u8 regs[6]; @@ -111,9 +113,9 @@ static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) case LTC4151_SENSE_H: /* * 20uV resolution. Convert to current as measured with - * an 1 mOhm sense resistor, in mA. + * a given sense resistor, in mA. */ - val = val * 20; + val = val * 20 * 1000 / data->shunt; break; case LTC4151_VIN_H: /* 25 mV per increment */ @@ -176,6 +178,7 @@ static int ltc4151_probe(struct i2c_client *client, struct device *dev = &client->dev; struct ltc4151_data *data; struct device *hwmon_dev; + u32 shunt; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) return -ENODEV; @@ -184,6 +187,15 @@ static int ltc4151_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->shunt = shunt; + data->client = client; mutex_init(&data->update_lock); @@ -199,10 +211,16 @@ static const struct i2c_device_id ltc4151_id[] = { }; MODULE_DEVICE_TABLE(i2c, ltc4151_id); +static const struct of_device_id ltc4151_match[] = { + { .compatible = "lltc,ltc4151" }, + {}, +}; + /* This is the driver that will be inserted */ static struct i2c_driver ltc4151_driver = { .driver = { .name = "ltc4151", + .of_match_table = of_match_ptr(ltc4151_match), }, .probe = ltc4151_probe, .id_table = ltc4151_id, -- 2.20.1