diff options
| author | David Fries <david@fries.net> | 2008-10-15 22:04:43 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-16 11:21:49 -0700 |
| commit | 6cd159744eaf212f3729d154f3881230a7c19eb2 (patch) | |
| tree | c2a76ecf90e0b156f480044f26d6379dba46d7eb /drivers | |
| parent | 6a158c0de791a81eb761ccf26ead1bd0834abac2 (diff) | |
W1: feature, w1_therm.c use strong pullup and documentation
Added strong pullup to thermal sensor driver and general documentation on
the sensor.
Signed-off-by: David Fries <david@fries.net>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/w1/slaves/w1_therm.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/w1/slaves/w1_therm.c b/drivers/w1/slaves/w1_therm.c index fb28acaeed6..e87f464a6fb 100644 --- a/drivers/w1/slaves/w1_therm.c +++ b/drivers/w1/slaves/w1_therm.c @@ -37,6 +37,14 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>"); MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family."); +/* Allow the strong pullup to be disabled, but default to enabled. + * If it was disabled a parasite powered device might not get the require + * current to do a temperature conversion. If it is enabled parasite powered + * devices have a better chance of getting the current required. + */ +static int w1_strong_pullup = 1; +module_param_named(strong_pullup, w1_strong_pullup, int, 0); + static u8 bad_roms[][9] = { {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87}, {} @@ -192,9 +200,12 @@ static ssize_t w1_therm_read_bin(struct kobject *kobj, int count = 0; unsigned int tm = 750; + /* 750ms strong pullup (or delay) after the convert */ + if (w1_strong_pullup) + w1_next_pullup(dev, tm); w1_write_8(dev, W1_CONVERT_TEMP); - - msleep(tm); + if (!w1_strong_pullup) + msleep(tm); if (!w1_reset_select_slave(sl)) { |