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i2c: Mention functionality flags in SMBus protocol documentation 

While the mapping between I2C adapter functionality flags and
i2c_smbus_*() helper functions is rather obvious, let's still document
it for clarity.

Also drop the reference to 2 command byte I2C block reads, there is no
support for that in the kernel at the moment.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
hifive-unleashed-5.1
Jean Delvare 2012-12-16 21:11:55 +01:00 committed by Jean Delvare
parent 8117e41e23
commit a1681781da
1 changed files with 31 additions and 9 deletions
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40
Documentation/i2c/smbus-protocol
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@ -23,6 +23,12 @@ don't match these function names. For some of the operations which pass a
single data byte, the functions using SMBus protocol operation names execute
a different protocol operation entirely.
Each transaction type corresponds to a functionality flag. Before calling a
transaction function, a device driver should always check (just once) for
the corresponding functionality flag to ensure that the underlying I2C
adapter supports the transaction in question. See
<file:Documentation/i2c/functionality> for the details.
Key to symbols
==============
@ -49,6 +55,8 @@ This sends a single bit to the device, at the place of the Rd/Wr bit.
A Addr Rd/Wr [A] P
Functionality flag: I2C_FUNC_SMBUS_QUICK
SMBus Receive Byte: i2c_smbus_read_byte()
==========================================
@ -60,6 +68,8 @@ the previous SMBus command.
S Addr Rd [A] [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_BYTE
SMBus Send Byte: i2c_smbus_write_byte()
========================================
@ -69,6 +79,8 @@ to a device. See Receive Byte for more information.
S Addr Wr [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_BYTE
SMBus Read Byte: i2c_smbus_read_byte_data()
============================================
@ -78,6 +90,8 @@ The register is specified through the Comm byte.
S Addr Wr [A] Comm [A] S Addr Rd [A] [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_BYTE_DATA
SMBus Read Word: i2c_smbus_read_word_data()
============================================
@ -88,6 +102,8 @@ byte. But this time, the data is a complete word (16 bits).
S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_WORD_DATA
Note the convenience function i2c_smbus_read_word_swapped is
available for reads where the two data bytes are the other way
around (not SMBus compliant, but very popular.)
@ -102,6 +118,8 @@ the Read Byte operation.
S Addr Wr [A] Comm [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_BYTE_DATA
SMBus Write Word: i2c_smbus_write_word_data()
==============================================
@ -112,6 +130,8 @@ specified through the Comm byte.
S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_WORD_DATA
Note the convenience function i2c_smbus_write_word_swapped is
available for writes where the two data bytes are the other way
around (not SMBus compliant, but very popular.)
@ -126,6 +146,8 @@ This command selects a device register (through the Comm byte), sends
S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A]
S Addr Rd [A] [DataLow] A [DataHigh] NA P
Functionality flag: I2C_FUNC_SMBUS_PROC_CALL
SMBus Block Read: i2c_smbus_read_block_data()
==============================================
@ -137,6 +159,8 @@ of data is specified by the device in the Count byte.
S Addr Wr [A] Comm [A]
S Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_BLOCK_DATA
SMBus Block Write: i2c_smbus_write_block_data()
================================================
@ -147,6 +171,8 @@ Comm byte. The amount of data is specified in the Count byte.
S Addr Wr [A] Comm [A] Count [A] Data [A] Data [A] ... [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_BLOCK_DATA
SMBus Block Write - Block Read Process Call
===========================================
@ -160,6 +186,8 @@ This command selects a device register (through the Comm byte), sends
S Addr Wr [A] Comm [A] Count [A] Data [A] ...
S Addr Rd [A] [Count] A [Data] ... A P
Functionality flag: I2C_FUNC_SMBUS_BLOCK_PROC_CALL
SMBus Host Notify
=================
@ -229,15 +257,7 @@ designated register that is specified through the Comm byte.
S Addr Wr [A] Comm [A]
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
I2C Block Read (2 Comm bytes)
=============================
This command reads a block of bytes from a device, from a
designated register that is specified through the two Comm bytes.
S Addr Wr [A] Comm1 [A] Comm2 [A]
S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
Functionality flag: I2C_FUNC_SMBUS_READ_I2C_BLOCK
I2C Block Write: i2c_smbus_write_i2c_block_data()
@ -249,3 +269,5 @@ Comm byte. Note that command lengths of 0, 2, or more bytes are
supported as they are indistinguishable from data.
S Addr Wr [A] Comm [A] Data [A] Data [A] ... [A] Data [A] P
Functionality flag: I2C_FUNC_SMBUS_WRITE_I2C_BLOCK