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-rw-r--r--Documentation/i2c/i2c-protocol.rst45
1 files changed, 23 insertions, 22 deletions
diff --git a/Documentation/i2c/i2c-protocol.rst b/Documentation/i2c/i2c-protocol.rst
index 2f8fcf671b2e..b2092f8f815d 100644
--- a/Documentation/i2c/i2c-protocol.rst
+++ b/Documentation/i2c/i2c-protocol.rst
@@ -1,26 +1,26 @@
-============
-I2C Protocol
-============
+================
+The I2C Protocol
+================
-This document describes the i2c protocol. Or will, when it is finished :-)
+This document describes the I2C protocol. Or will, when it is finished :-)
Key to symbols
==============
=============== =============================================================
-S (1 bit) : Start bit
-P (1 bit) : Stop bit
-Rd/Wr (1 bit) : Read/Write bit. Rd equals 1, Wr equals 0.
-A, NA (1 bit) : Accept and reverse accept bit.
-Addr (7 bits): I2C 7 bit address. Note that this can be expanded as usual to
+S Start condition
+P Stop condition
+Rd/Wr (1 bit) Read/Write bit. Rd equals 1, Wr equals 0.
+A, NA (1 bit) Acknowledge (ACK) and Not Acknowledge (NACK) bit
+Addr (7 bits) I2C 7 bit address. Note that this can be expanded as usual to
get a 10 bit I2C address.
-Comm (8 bits): Command byte, a data byte which often selects a register on
+Comm (8 bits) Command byte, a data byte which often selects a register on
the device.
-Data (8 bits): A plain data byte. Sometimes, I write DataLow, DataHigh
+Data (8 bits) A plain data byte. Sometimes, I write DataLow, DataHigh
for 16 bit data.
-Count (8 bits): A data byte containing the length of a block operation.
+Count (8 bits) A data byte containing the length of a block operation.
-[..]: Data sent by I2C device, as opposed to data sent by the
+[..] Data sent by I2C device, as opposed to data sent by the
host adapter.
=============== =============================================================
@@ -28,7 +28,7 @@ Count (8 bits): A data byte containing the length of a block operation.
Simple send transaction
=======================
-This corresponds to i2c_master_send::
+Implemented by i2c_master_send()::
S Addr Wr [A] Data [A] Data [A] ... [A] Data [A] P
@@ -36,7 +36,7 @@ This corresponds to i2c_master_send::
Simple receive transaction
==========================
-This corresponds to i2c_master_recv::
+Implemented by i2c_master_recv()::
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
@@ -44,11 +44,11 @@ This corresponds to i2c_master_recv::
Combined transactions
=====================
-This corresponds to i2c_transfer
+Implemented by i2c_transfer().
-They are just like the above transactions, but instead of a stop bit P
-a start bit S is sent and the transaction continues. An example of
-a byte read, followed by a byte write::
+They are just like the above transactions, but instead of a stop
+condition P a start condition S is sent and the transaction continues.
+An example of a byte read, followed by a byte write::
S Addr Rd [A] [Data] NA S Addr Wr [A] Data [A] P
@@ -57,7 +57,7 @@ Modified transactions
=====================
The following modifications to the I2C protocol can also be generated by
-setting these flags for i2c messages. With the exception of I2C_M_NOSTART, they
+setting these flags for I2C messages. With the exception of I2C_M_NOSTART, they
are usually only needed to work around device issues:
I2C_M_IGNORE_NAK:
@@ -77,8 +77,9 @@ I2C_M_NOSTART:
S Addr Rd [A] [Data] NA Data [A] P
If you set the I2C_M_NOSTART variable for the first partial message,
- we do not generate Addr, but we do generate the startbit S. This will
- probably confuse all other clients on your bus, so don't try this.
+ we do not generate Addr, but we do generate the start condition S.
+ This will probably confuse all other clients on your bus, so don't
+ try this.
This is often used to gather transmits from multiple data buffers in
system memory into something that appears as a single transfer to the