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-rw-r--r--Documentation/i2c/functionality9
-rw-r--r--Documentation/i2c/i2c-protocol9
-rw-r--r--Documentation/i2c/muxes/i2c-mux-gpio (renamed from Documentation/i2c/muxes/gpio-i2cmux)12
3 files changed, 20 insertions, 10 deletions
diff --git a/Documentation/i2c/functionality b/Documentation/i2c/functionality
index 42c17c1fb3c..b0ff2ab596c 100644
--- a/Documentation/i2c/functionality
+++ b/Documentation/i2c/functionality
@@ -18,9 +18,9 @@ For the most up-to-date list of functionality constants, please check
adapters typically can not do these)
I2C_FUNC_10BIT_ADDR Handles the 10-bit address extensions
I2C_FUNC_PROTOCOL_MANGLING Knows about the I2C_M_IGNORE_NAK,
- I2C_M_REV_DIR_ADDR, I2C_M_NOSTART and
- I2C_M_NO_RD_ACK flags (which modify the
- I2C protocol!)
+ I2C_M_REV_DIR_ADDR and I2C_M_NO_RD_ACK
+ flags (which modify the I2C protocol!)
+ I2C_FUNC_NOSTART Can skip repeated start sequence
I2C_FUNC_SMBUS_QUICK Handles the SMBus write_quick command
I2C_FUNC_SMBUS_READ_BYTE Handles the SMBus read_byte command
I2C_FUNC_SMBUS_WRITE_BYTE Handles the SMBus write_byte command
@@ -50,6 +50,9 @@ A few combinations of the above flags are also defined for your convenience:
emulated by a real I2C adapter (using
the transparent emulation layer)
+In kernel versions prior to 3.5 I2C_FUNC_NOSTART was implemented as
+part of I2C_FUNC_PROTOCOL_MANGLING.
+
ADAPTER IMPLEMENTATION
----------------------
diff --git a/Documentation/i2c/i2c-protocol b/Documentation/i2c/i2c-protocol
index 10518dd5881..0b3e62d1f77 100644
--- a/Documentation/i2c/i2c-protocol
+++ b/Documentation/i2c/i2c-protocol
@@ -49,7 +49,9 @@ a byte read, followed by a byte write:
Modified transactions
=====================
-We have found some I2C devices that needs the following modifications:
+The following modifications to the I2C protocol can also be generated,
+with the exception of I2C_M_NOSTART these are usually only needed to
+work around device issues:
Flag I2C_M_NOSTART:
In a combined transaction, no 'S Addr Wr/Rd [A]' is generated at some
@@ -60,6 +62,11 @@ We have found some I2C devices that needs the following modifications:
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.
+ This is often used to gather transmits from multiple data buffers in
+ system memory into something that appears as a single transfer to the
+ I2C device but may also be used between direction changes by some
+ rare devices.
+
Flags I2C_M_REV_DIR_ADDR
This toggles the Rd/Wr flag. That is, if you want to do a write, but
need to emit an Rd instead of a Wr, or vice versa, you set this
diff --git a/Documentation/i2c/muxes/gpio-i2cmux b/Documentation/i2c/muxes/i2c-mux-gpio
index 811cd78d4cd..bd9b2299b73 100644
--- a/Documentation/i2c/muxes/gpio-i2cmux
+++ b/Documentation/i2c/muxes/i2c-mux-gpio
@@ -1,11 +1,11 @@
-Kernel driver gpio-i2cmux
+Kernel driver i2c-gpio-mux
Author: Peter Korsgaard <peter.korsgaard@barco.com>
Description
-----------
-gpio-i2cmux is an i2c mux driver providing access to I2C bus segments
+i2c-gpio-mux is an i2c mux driver providing access to I2C bus segments
from a master I2C bus and a hardware MUX controlled through GPIO pins.
E.G.:
@@ -26,16 +26,16 @@ according to the settings of the GPIO pins 1..N.
Usage
-----
-gpio-i2cmux uses the platform bus, so you need to provide a struct
+i2c-gpio-mux uses the platform bus, so you need to provide a struct
platform_device with the platform_data pointing to a struct
gpio_i2cmux_platform_data with the I2C adapter number of the master
bus, the number of bus segments to create and the GPIO pins used
-to control it. See include/linux/gpio-i2cmux.h for details.
+to control it. See include/linux/i2c-gpio-mux.h for details.
E.G. something like this for a MUX providing 4 bus segments
controlled through 3 GPIO pins:
-#include <linux/gpio-i2cmux.h>
+#include <linux/i2c-gpio-mux.h>
#include <linux/platform_device.h>
static const unsigned myboard_gpiomux_gpios[] = {
@@ -57,7 +57,7 @@ static struct gpio_i2cmux_platform_data myboard_i2cmux_data = {
};
static struct platform_device myboard_i2cmux = {
- .name = "gpio-i2cmux",
+ .name = "i2c-gpio-mux",
.id = 0,
.dev = {
.platform_data = &myboard_i2cmux_data,