--- /dev/null
+#ifndef _IPXE_I2C_H
+#define _IPXE_I2C_H
+
+/** @file
+ *
+ * I2C interface
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdint.h>
+#include <ipxe/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 /* _IPXE_I2C_H */
Code Review / kvmfornfv.git / blobdiff