diff options
Diffstat (limited to 'drivers/w1/masters/ds2482.c')
| -rw-r--r-- | drivers/w1/masters/ds2482.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/w1/masters/ds2482.c b/drivers/w1/masters/ds2482.c index b05e8fefbabd..2e30db1b1a43 100644 --- a/drivers/w1/masters/ds2482.c +++ b/drivers/w1/masters/ds2482.c @@ -24,6 +24,19 @@ #include "../w1_int.h" /** + * Allow the active pullup to be disabled, default is enabled. + * + * Note from the DS2482 datasheet: + * The APU bit controls whether an active pullup (controlled slew-rate + * transistor) or a passive pullup (Rwpu resistor) will be used to drive + * a 1-Wire line from low to high. When APU = 0, active pullup is disabled + * (resistor mode). Active Pullup should always be selected unless there is + * only a single slave on the 1-Wire line. + */ +static int ds2482_active_pullup = 1; +module_param_named(active_pullup, ds2482_active_pullup, int, 0644); + +/** * The DS2482 registers - there are 3 registers that are addressed by a read * pointer. The read pointer is set by the last command executed. * @@ -138,6 +151,9 @@ struct ds2482_data { */ static inline u8 ds2482_calculate_config(u8 conf) { + if (ds2482_active_pullup) + conf |= DS2482_REG_CFG_APU; + return conf | ((~conf & 0x0f) << 4); } @@ -546,6 +562,8 @@ static int ds2482_remove(struct i2c_client *client) module_i2c_driver(ds2482_driver); +MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \ + "0-disable, 1-enable (default)"); MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); MODULE_DESCRIPTION("DS2482 driver"); MODULE_LICENSE("GPL"); |