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authorEvgeniy Polyakov <johnpol@2ka.mipt.ru>2006-03-23 11:11:58 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2006-06-22 14:22:50 -0400
commitf522d2396138e68bcb9cc5650aa368a81d7f7ff0 (patch)
tree3446d411b996b19094856c5729725e0e43ff4b0e /Documentation
parent52ab3f3dc711eeccbfbcc5d4f5c5d9b9ff59650f (diff)
[PATCH] w1: Added default generic read/write operations.
Special file in each w1 slave device's directory called "rw" is created each time new slave and no appropriate w1 family is registered. "rw" file supports read and write operations, 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. Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/w1/w1.generic18
1 files changed, 15 insertions, 3 deletions
diff --git a/Documentation/w1/w1.generic b/Documentation/w1/w1.generic
index f937fbe1cacb..4c6509dd4789 100644
--- 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:
27 27
28When a device is found on the bus, w1 core checks if driver for it's family is 28When a device is found on the bus, w1 core checks if driver for it's family is
29loaded. If so, the family driver is attached to the slave. 29loaded. If so, the family driver is attached to the slave.
30If there is no driver for the family, a simple sysfs entry is created 30If there is no driver for the family, default one is assigned, which allows to perform
31for the slave device. 31almost any kind of operations. Each logical operation is a transaction
32in nature, which can contain several (two or one) low-level operations.
33Let's see how one can read EEPROM context:
341. one must write control buffer, i.e. buffer containing command byte
35and two byte address. At this step bus is reset and appropriate device
36is selected using either W1_SKIP_ROM or W1_MATCH_ROM command.
37Then provided control buffer is being written to the wire.
382. reading. This will issue reading eeprom response.
39
40It is possible that between 1. and 2. w1 master thread will reset bus for searching
41and slave device will be even removed, but in this case 0xff will
42be read, since no device was selected.
32 43
33 44
34W1 device families 45W1 device families
@@ -89,4 +100,5 @@ driver - (standard) symlink to the w1 driver
89name - the device name, usually the same as the directory name 100name - the device name, usually the same as the directory name
90w1_slave - (optional) a binary file whose meaning depends on the 101w1_slave - (optional) a binary file whose meaning depends on the
91 family driver 102 family driver
92 103rw - (optional) created for slave devices which do not have
104 appropriate family driver. Allows to read/write binary data.