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#ifndef _GPXE_I2C_H
#define _GPXE_I2C_H
/** @file
*
* I2C interface
*
*/
#include <stdint.h>
/** An I2C device
*
* An I2C device represents a specific slave device on an I2C bus. It
* is accessed via an I2C interface.
*/
struct i2c_device {
/** Address of this device */
unsigned int address;
/** Flag indicating a ten-bit address format */
int tenbit;
};
/** An I2C interface
*
* An I2C interface provides access to an I2C bus, via which I2C
* devices may be reached.
*/
struct i2c_interface {
/**
* Read data from I2C device
*
* @v i2c I2C interface
* @v i2cdev I2C device
* @v offset Starting offset within the device
* @v data Data buffer
* @v len Length of data buffer
* @ret rc Return status code
*/
int ( * read ) ( struct i2c_interface *i2c, struct i2c_device *i2cdev,
unsigned int offset, uint8_t *data,
unsigned int len );
/**
* Write data to I2C device
*
* @v i2c I2C interface
* @v i2cdev I2C device
* @v offset Starting offset within the device
* @v data Data buffer
* @v len Length of data buffer
* @ret rc Return status code
*/
int ( * write ) ( struct i2c_interface *i2c, struct i2c_device *i2cdev,
unsigned int offset, const uint8_t *data,
unsigned int len );
};
/** A bit-bashing I2C interface
*
* This provides a standardised way to construct I2C buses via a
* bit-bashing interface.
*/
struct i2c_bit_basher {
/** I2C interface */
struct i2c_interface i2c;
/** Bit-bashing interface */
struct bit_basher basher;
};
/** Ten-bit address marker
*
* This value is ORed with the I2C device address to indicate a
* ten-bit address format on the bus.
*/
#define I2C_TENBIT_ADDRESS 0x7800
/** An I2C write command */
#define I2C_WRITE 0
/** An I2C read command */
#define I2C_READ 1
/** Bit indices used for I2C bit-bashing interface */
enum {
/** Serial clock */
I2C_BIT_SCL = 0,
/** Serial data */
I2C_BIT_SDA,
};
/** Delay required for bit-bashing operation */
#define I2C_UDELAY 5
/**
* Check presence of I2C device
*
* @v i2c I2C interface
* @v i2cdev I2C device
* @ret rc Return status code
*
* Checks for the presence of the device on the I2C bus by attempting
* a zero-length write.
*/
static inline int i2c_check_presence ( struct i2c_interface *i2c,
struct i2c_device *i2cdev ) {
return i2c->write ( i2c, i2cdev, 0, NULL, 0 );
}
extern void init_i2c_bit_basher ( struct i2c_bit_basher *i2cbit );
#endif /* _GPXE_I2C_H */
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