diff options
Diffstat (limited to 'Documentation/i2c')
| -rw-r--r-- | Documentation/i2c/functionality | 9 | ||||
| -rw-r--r-- | Documentation/i2c/i2c-protocol | 9 | ||||
| -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 42c17c1fb3cd..b0ff2ab596ce 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 10518dd58814..0b3e62d1f77a 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 811cd78d4cdc..bd9b2299b739 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, |
