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
GPIO(4) BSD Kernel Interfaces Manual GPIO(4)NAME
gpiobus -- GPIO bus system
SYNOPSIS
To compile these devices into your kernel and use the device hints, place the following lines in your kernel configuration file:
device gpio
device gpioc
device gpioiic
device gpioled
Additional device entries for the ARM architecture include:
device a10_gpio
device bcm_gpio
device imx51_gpio
device lpcgpio
device mv_gpio
device ti_gpio
device gpio_avila
device gpio_cambria
device zy7_gpio
device pxagpio
Additional device entries for the MIPS architecture include:
device ar71xxx_gpio
device octeon_gpio
device rt305_gpio
Additional device entries for the POWERPC architecture include:
device wiigpio
device macgpio
DESCRIPTION
The gpiobus system provides a simple interface to the GPIO pins that are usually available on embedded architectures and can provide bit
banging style devices to the system.
The acronym GPIO means ``General-Purpose Input/Output.''
The BUS physically consists of multiple pins that can be configured for input/output, IRQ delivery, SDA/SCL iicbus use, etc.
On some embedded architectures (like MIPS), discovery of the bus and configuration of the pins is done via device.hints(5) in the platform's
kernel config(5) file.
On some others (like ARM), where FDT(4) is used to describe the device tree, the bus discovery is done via the DTS passed to the kernel,
being either statically compiled in, or by a variety of ways where the boot loader (or Open Firmware enabled system) passes the DTS blob to
the kernel at boot.
The following device.hints(5) are only provided by the ar71xx_gpio driver:
hint.gpio.%d.pinmask This is a bitmask of pins on the GPIO board that we would like to expose for use to the host operating system. To
expose pin 0, 4 and 7, use the bitmask of 10010001 converted to the hexadecimal value 0x0091.
hint.gpio.%d.pinon This is a bitmask of pins on the GPIO board that will be set to ON at host start. To set pin 2, 5 and 13 to be set ON
at boot, use the bitmask of 10000000010010 converted to the hexadecimal value 0x2012.
hint.gpio.function_set
hint.gpio.function_clear
These are bitmasks of pins that will remap a pin to handle a specific function (USB, UART TX/RX, etc) in the Atheros
function registers. This is mainly used to set/clear functions that we need when they are set up or not set up by
uBoot.
Simply put, each pin of the GPIO interface is connected to an input/output of some device in a system.
SEE ALSO gpioiic(4), gpioled(4), iicbus(4), gpioctl(8)HISTORY
The gpiobus manual page first appeared in FreeBSD 10.0.
AUTHORS
This manual page was written by Sean Bruno <sbruno@FreeBSD.org>.
BSD November 5, 2013 BSD