STRUCT I2C_BUS_RECOV(9) I2C and SMBus Subsystem STRUCT I2C_BUS_RECOV(9)NAME
struct_i2c_bus_recovery_info - I2C bus recovery information
SYNOPSIS
struct i2c_bus_recovery_info {
int (* recover_bus) (struct i2c_adapter *);
int (* get_scl) (struct i2c_adapter *);
void (* set_scl) (struct i2c_adapter *, int val);
int (* get_sda) (struct i2c_adapter *);
void (* prepare_recovery) (struct i2c_bus_recovery_info *bri);
void (* unprepare_recovery) (struct i2c_bus_recovery_info *bri);
int scl_gpio;
int sda_gpio;
};
MEMBERS
recover_bus
Recover routine. Either pass driver's recover_bus routine, or i2c_generic_scl_recovery or i2c_generic_gpio_recovery.
get_scl
This gets current value of SCL line. Mandatory for generic SCL recovery. Used internally for generic GPIO recovery.
set_scl
This sets/clears SCL line. Mandatory for generic SCL recovery. Used internally for generic GPIO recovery.
get_sda
This gets current value of SDA line. Optional for generic SCL recovery. Used internally, if sda_gpio is a valid GPIO, for generic GPIO
recovery.
prepare_recovery
This will be called before starting recovery. Platform may configure padmux here for SDA/SCL line or something else they want.
unprepare_recovery
This will be called after completing recovery. Platform may configure padmux here for SDA/SCL line or something else they want.
scl_gpio
gpio number of the SCL line. Only required for GPIO recovery.
sda_gpio
gpio number of the SDA line. Only required for GPIO recovery.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 STRUCT I2C_BUS_RECOV(9)
Check Out this Related Man Page
GPIOIIC(4) BSD Kernel Interfaces Manual GPIOIIC(4)NAME
gpioiic -- GPIO I2C bit-banging device driver
SYNOPSIS
To compile this driver into the kernel, place the following lines in your kernel configuration file:
device gpio
device gpioiic
device iic
device iicbb
device iicbus
DESCRIPTION
The gpioiic driver provides an IIC bit-banging interface using two GPIO pins for the SCL and SDA on the gpiobus. gpioiic implements an open
collector kind of output, as recommended by the standard, when driving the pins on the gpiobus, i.e, they are never switched to the logical
value of '1', or they are '0' or simply open (Hi-Z/tri-state). So the pullup resistors are required so gpioiic can work.
On a device.hints(5) based system, like MIPS, these values are configurable for the gpioiic:
hint.gpioiic.%d.at The gpiobus you are attaching to. Normally just gpiobus0.
hint.gpioiic.%d.pins This is a bitmask of the pins on the gpiobus that are to be used for SCLOCK and SDATA from the GPIO IIC bit-banging
bus. To configure pin 0 and 7, use the bitmask of 0b10000001 and convert it to a hexadecimal value of 0x0081. Please
note that this mask should only ever have two bits set (any other bits - i.e., pins - will be ignored).
hint.gpioiic.%d.scl Indicates which bit in the hint.gpioiic.%d.pins should be used as the SCLOCK source. Optional, defaults to 0.
hint.gpioiic.%d.sda Indicates which bit in the hint.gpioiic.%d.pins should be used as the SDATA source. Optional, defaults to 1.
On a FDT(4) based system, like ARM, the DTS part for a gpioiic device usually looks like:
gpio: gpio {
gpio-controller;
...
gpioiic0 {
compatible = "gpioiic";
/*
* Attach to GPIO pins 21 and 22. Set them
* initially as inputs.
*/
gpios = <&gpio 21 1 0
&gpio 22 1 0>;
scl = <0>; /* GPIO pin 21 - optional */
sda = <1>; /* GPIO pin 22 - optional */
/* This is an example of a gpioiic child. */
gpioiic-child0 {
compatible = "lm75";
i2c-address = <0x4f>;
};
};
};
Where:
compatible Should always be set to "gpioiic".
gpios The gpios property indicates which GPIO pins should be used for SCLOCK and SDATA on the GPIO IIC bit-banging bus. For more
details about the gpios property, please consult /usr/src/sys/boot/fdt/dts/bindings-gpio.txt.
scl The scl option indicates which bit in the gpios should be used as the SCLOCK source. Optional, defaults to 0.
sda The sda option indicates which bit in the gpios should be used as the SDATA source. Optional, defaults to 1.
SEE ALSO fdt(4), gpio(4), gpioled(4), iic(4), iicbb(4), iicbus(4)HISTORY
The gpioiic manual page first appeared in FreeBSD 10.1.
AUTHORS
This manual page was written by Luiz Otavio O Souza.
BSD May 14, 2014 BSD