| #ifndef _GPXE_I2C_H |
| #define _GPXE_I2C_H |
| |
| /** @file |
| * |
| * I2C interface |
| * |
| */ |
| |
| FILE_LICENCE ( GPL2_OR_LATER ); |
| |
| #include <stdint.h> |
| #include <gpxe/bitbash.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 |
| * |
| * The actual address sent on the bus will look like |
| * |
| * <start> <device address> <word address overflow> <r/w> |
| * |
| * The "word address overflow" is any excess bits from the |
| * word address, i.e. any portion that does not fit within the |
| * defined word address length. |
| */ |
| unsigned int dev_addr; |
| /** Device address length, in bytes |
| * |
| * This is the number of bytes that comprise the device |
| * address, defined to be the portion that terminates with the |
| * read/write bit. |
| */ |
| unsigned int dev_addr_len; |
| /** Word adddress length, in bytes |
| * |
| * This is the number of bytes that comprise the word address, |
| * defined to be the portion that starts after the read/write |
| * bit and ends before the first data byte. |
| * |
| * For some devices, this length will be zero (i.e. the word |
| * address is contained entirely within the "word address |
| * overflow"). |
| */ |
| unsigned int word_addr_len; |
| }; |
| |
| /** 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 |
| |
| /** Maximum number of cycles to use when attempting a bus reset */ |
| #define I2C_RESET_MAX_CYCLES 32 |
| |
| /** |
| * 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 int init_i2c_bit_basher ( struct i2c_bit_basher *i2cbit, |
| struct bit_basher_operations *bash_op ); |
| |
| /** |
| * Initialise generic I2C EEPROM device |
| * |
| * @v i2cdev I2C device |
| */ |
| static inline __always_inline void |
| init_i2c_eeprom ( struct i2c_device *i2cdev, unsigned int dev_addr ) { |
| i2cdev->dev_addr = dev_addr; |
| i2cdev->dev_addr_len = 1; |
| i2cdev->word_addr_len = 1; |
| } |
| |
| /** |
| * Initialise Atmel AT24C11 |
| * |
| * @v i2cdev I2C device |
| */ |
| static inline __always_inline void |
| init_at24c11 ( struct i2c_device *i2cdev ) { |
| /* This chip has no device address; it must be the only chip |
| * on the bus. The word address is contained entirely within |
| * the device address field. |
| */ |
| i2cdev->dev_addr = 0; |
| i2cdev->dev_addr_len = 1; |
| i2cdev->word_addr_len = 0; |
| } |
| |
| #endif /* _GPXE_I2C_H */ |