Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6

[safe/jmp/linux-2.6] / Documentation / w1 / w1.generic

diff --git a/Documentation/w1/w1.generic b/Documentation/w1/w1.generic
index f937fbe..e3333ee 100644 (file)
--- a/Documentation/w1/w1.generic
+++ b/Documentation/w1/w1.generic
@@ -27,8 +27,19 @@ When a w1 master driver registers with the w1 subsystem, the following occurs:
 
 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.
+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
 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.