1 #ifndef _GPXE_I2C_H 2 #define _GPXE_I2C_H 3 4 /** @file 5 * 6 * I2C interface 7 * 8 */ 9 10 FILE_LICENCE ( GPL2_OR_LATER ); 11 12 #include <stdint.h> 13 #include <gpxe/bitbash.h> 14 15 /** An I2C device 16 * 17 * An I2C device represents a specific slave device on an I2C bus. It 18 * is accessed via an I2C interface. 19 */ 20 struct i2c_device { 21 /** Address of this device 22 * 23 * The actual address sent on the bus will look like 24 * 25 * <start> <device address> <word address overflow> <r/w> 26 * 27 * The "word address overflow" is any excess bits from the 28 * word address, i.e. any portion that does not fit within the 29 * defined word address length. 30 */ 31 unsigned int dev_addr; 32 /** Device address length, in bytes 33 * 34 * This is the number of bytes that comprise the device 35 * address, defined to be the portion that terminates with the 36 * read/write bit. 37 */ 38 unsigned int dev_addr_len; 39 /** Word adddress length, in bytes 40 * 41 * This is the number of bytes that comprise the word address, 42 * defined to be the portion that starts after the read/write 43 * bit and ends before the first data byte. 44 * 45 * For some devices, this length will be zero (i.e. the word 46 * address is contained entirely within the "word address 47 * overflow"). 48 */ 49 unsigned int word_addr_len; 50 }; 51 52 /** An I2C interface 53 * 54 * An I2C interface provides access to an I2C bus, via which I2C 55 * devices may be reached. 56 */ 57 struct i2c_interface { 58 /** 59 * Read data from I2C device 60 * 61 * @v i2c I2C interface 62 * @v i2cdev I2C device 63 * @v offset Starting offset within the device 64 * @v data Data buffer 65 * @v len Length of data buffer 66 * @ret rc Return status code 67 */ 68 int ( * read ) ( struct i2c_interface *i2c, struct i2c_device *i2cdev, 69 unsigned int offset, uint8_t *data, 70 unsigned int len ); 71 /** 72 * Write data to I2C device 73 * 74 * @v i2c I2C interface 75 * @v i2cdev I2C device 76 * @v offset Starting offset within the device 77 * @v data Data buffer 78 * @v len Length of data buffer 79 * @ret rc Return status code 80 */ 81 int ( * write ) ( struct i2c_interface *i2c, struct i2c_device *i2cdev, 82 unsigned int offset, const uint8_t *data, 83 unsigned int len ); 84 }; 85 86 /** A bit-bashing I2C interface 87 * 88 * This provides a standardised way to construct I2C buses via a 89 * bit-bashing interface. 90 */ 91 struct i2c_bit_basher { 92 /** I2C interface */ 93 struct i2c_interface i2c; 94 /** Bit-bashing interface */ 95 struct bit_basher basher; 96 }; 97 98 /** Ten-bit address marker 99 * 100 * This value is ORed with the I2C device address to indicate a 101 * ten-bit address format on the bus. 102 */ 103 #define I2C_TENBIT_ADDRESS 0x7800 104 105 /** An I2C write command */ 106 #define I2C_WRITE 0 107 108 /** An I2C read command */ 109 #define I2C_READ 1 110 111 /** Bit indices used for I2C bit-bashing interface */ 112 enum { 113 /** Serial clock */ 114 I2C_BIT_SCL = 0, 115 /** Serial data */ 116 I2C_BIT_SDA, 117 }; 118 119 /** Delay required for bit-bashing operation */ 120 #define I2C_UDELAY 5 121 122 /** Maximum number of cycles to use when attempting a bus reset */ 123 #define I2C_RESET_MAX_CYCLES 32 124 125 /** 126 * Check presence of I2C device 127 * 128 * @v i2c I2C interface 129 * @v i2cdev I2C device 130 * @ret rc Return status code 131 * 132 * Checks for the presence of the device on the I2C bus by attempting 133 * a zero-length write. 134 */ 135 static inline int i2c_check_presence ( struct i2c_interface *i2c, 136 struct i2c_device *i2cdev ) { 137 return i2c->write ( i2c, i2cdev, 0, NULL, 0 ); 138 } 139 140 extern int init_i2c_bit_basher ( struct i2c_bit_basher *i2cbit, 141 struct bit_basher_operations *bash_op ); 142 143 /** 144 * Initialise generic I2C EEPROM device 145 * 146 * @v i2cdev I2C device 147 */ 148 static inline __always_inline void 149 init_i2c_eeprom ( struct i2c_device *i2cdev, unsigned int dev_addr ) { 150 i2cdev->dev_addr = dev_addr; 151 i2cdev->dev_addr_len = 1; 152 i2cdev->word_addr_len = 1; 153 } 154 155 /** 156 * Initialise Atmel AT24C11 157 * 158 * @v i2cdev I2C device 159 */ 160 static inline __always_inline void 161 init_at24c11 ( struct i2c_device *i2cdev ) { 162 /* This chip has no device address; it must be the only chip 163 * on the bus. The word address is contained entirely within 164 * the device address field. 165 */ 166 i2cdev->dev_addr = 0; 167 i2cdev->dev_addr_len = 1; 168 i2cdev->word_addr_len = 0; 169 } 170 171 #endif /* _GPXE_I2C_H */ 172
