123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111 |
- #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 */
|