6a158c0de7
Add a strong pullup option to the w1 system. This supplies extra power for parasite powered devices. There is a w1_master_pullup sysfs entry and enable_pullup module parameter to enable or disable the strong pullup. The one wire bus requires at a minimum one wire and ground. The common wire is used for sending and receiving data as well as supplying power to devices that are parasite powered of which temperature sensors can be one example. The bus must be idle and left high while a temperature conversion is in progress, in addition the normal pullup resister on larger networks or even higher temperatures might not supply enough power. The pullup resister can't provide too much pullup current, because devices need to pull the bus down to write a value. This enables the strong pullup for supported hardware, which can supply more current when requested. Unsupported hardware will just delay with the bus high. The hardware USB 2490 one wire bus master has a bit on some commands which will enable the strong pullup as soon as the command finishes executing. To use strong pullup, call the new w1_next_pullup function to register the duration. The next write command will call set_pullup before sending the data, and reset the duration to zero once it returns. Switched from simple_strtol to strict_strtol. Signed-off-by: David Fries <david@fries.net> Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| masters | ||
| slaves | ||
| Kconfig | ||
| Makefile | ||
| w1.c | ||
| w1.h | ||
| w1_family.c | ||
| w1_family.h | ||
| w1_int.c | ||
| w1_int.h | ||
| w1_io.c | ||
| w1_log.h | ||
| w1_netlink.c | ||
| w1_netlink.h | ||