diff options
Diffstat (limited to 'Documentation/w1/w1.generic')
| -rw-r--r-- | Documentation/w1/w1.generic | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/Documentation/w1/w1.generic b/Documentation/w1/w1.generic index f937fbe1cac..b2033c64c7d 100644 --- a/Documentation/w1/w1.generic +++ b/Documentation/w1/w1.generic @@ -25,10 +25,21 @@ When a w1 master driver registers with the w1 subsystem, the following occurs: - sysfs entries for that w1 master are created - the w1 bus is periodically searched for new slave devices -When a device is found on the bus, w1 core checks if driver for it's family is -loaded. If so, the family driver is attached to the slave. -If there is no driver for the family, a simple sysfs entry is created -for the slave device. +When a device is found on the bus, w1 core tries to load the driver for its family +and check if it is loaded. If so, the family driver is attached to the slave. +If there is no driver for the family, default one is assigned, which allows to perform +almost any kind of operations. Each logical operation is a transaction +in nature, which can contain several (two or one) low-level operations. +Let's see how one can read EEPROM context: +1. one must write control buffer, i.e. buffer containing command byte +and two byte address. At this step bus is reset and appropriate device +is selected using either W1_SKIP_ROM or W1_MATCH_ROM command. +Then provided control buffer is being written to the wire. +2. reading. This will issue reading eeprom response. + +It is possible that between 1. and 2. w1 master thread will reset bus for searching +and slave device will be even removed, but in this case 0xff will +be read, since no device was selected. W1 device families @@ -68,10 +79,13 @@ w1 master sysfs interface <xx-xxxxxxxxxxxxx> - a directory for a found device. The format is family-serial bus - (standard) symlink to the w1 bus driver - (standard) symlink to the w1 driver +w1_master_add - Manually register a slave device w1_master_attempts - the number of times a search was attempted w1_master_max_slave_count - - the maximum slaves that may be attached to a master + - maximum number of slaves to search for at a time w1_master_name - the name of the device (w1_bus_masterX) +w1_master_pullup - 5V strong pullup 0 enabled, 1 disabled +w1_master_remove - Manually remove a slave device w1_master_search - the number of searches left to do, -1=continual (default) w1_master_slave_count - the number of slaves found @@ -79,7 +93,13 @@ w1_master_slaves - the names of the slaves, one per line w1_master_timeout - the delay in seconds between searches If you have a w1 bus that never changes (you don't add or remove devices), -you can set w1_master_search to a positive value to disable searches. +you can set the module parameter search_count to a small positive number +for an initially small number of bus searches. Alternatively it could be +set to zero, then manually add the slave device serial numbers by +w1_master_add device file. The w1_master_add and w1_master_remove files +generally only make sense when searching is disabled, as a search will +redetect manually removed devices that are present and timeout manually +added devices that aren't on the bus. w1 slave sysfs interface @@ -89,4 +109,5 @@ driver - (standard) symlink to the w1 driver name - the device name, usually the same as the directory name w1_slave - (optional) a binary file whose meaning depends on the family driver - +rw - (optional) created for slave devices which do not have + appropriate family driver. Allows to read/write binary data. |