path: root/Documentation/i2c
diff options
authorGuenter Roeck <linux@roeck-us.net>2014-07-17 09:56:03 -0700
committerWolfram Sang <wsa@the-dreams.de>2014-07-17 19:11:35 +0200
commit6f16b75a41abbbd11c4c8b7c62eb66604879b981 (patch)
tree6183b1ff9454533e8c4bd14809749052eb1fea3c /Documentation/i2c
parent281ec367bff42304e0dc5cbc8d267ce9251478b7 (diff)
i2c: stub: Add support for SMBus block commands
SMBus block commands are different to I2C block commands since the returned data is not normally accessible with byte or word commands on other command offsets. Add linked list of 'block' commands to support those commands. Access mechanism is quite simple: Block commands must be written before they can be read. Subsequent writes can be partial. Block read commands always return the number of bytes associated with the longest previous write. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Jean Delvare <jdelvare@suse.de> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'Documentation/i2c')
1 files changed, 10 insertions, 2 deletions
diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub
index fa4b669c166b..a0fe7a04a3bd 100644
--- a/Documentation/i2c/i2c-stub
+++ b/Documentation/i2c/i2c-stub
@@ -2,9 +2,9 @@ MODULE: i2c-stub
-This module is a very simple fake I2C/SMBus driver. It implements five
+This module is a very simple fake I2C/SMBus driver. It implements six
types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, (r/w)
-word data, and (r/w) I2C block data.
+word data, (r/w) I2C block data, and (r/w) SMBus block data.
You need to provide chip addresses as a module parameter when loading this
driver, which will then only react to SMBus commands to these addresses.
@@ -19,6 +19,14 @@ A pointer register with auto-increment is implemented for all byte
operations. This allows for continuous byte reads like those supported by
EEPROMs, among others.
+SMBus block command support is disabled by default, and must be enabled
+explicitly by setting the respective bits (0x03000000) in the functionality
+module parameter.
+SMBus block commands must be written to configure an SMBus command for
+SMBus block operations. Writes can be partial. Block read commands always
+return the number of bytes selected with the largest write so far.
The typical use-case is like this:
1. load this module
2. use i2cset (from the i2c-tools project) to pre-load some data

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