DCMD_I2C

#include <hw/i2c.h>

#define DCMD_I2C_RECV               __DIOTF(_DCMD_I2C, 6, i2c_recv_t)

The arguments to devctl() are:

Argument	Value
`filedes`	A file descriptor that you obtained by opening the device.
`dcmd`	DCMD_I2C_RECV
`dev_data_ptr`	A pointer to a i2c_recv_t, followed by the receive buffer
`n_bytes`	`sizeof(i2c_recv_t)` plus the size of the receive buffer
`dev_info_ptr`	NULL

The DCMD_I2C_RECV command executes a master receive transaction. It returns when the transaction is complete.

Input

i2c_recv_t — the message header
uint8_t[] — the receive buffer

Output

i2c_recv_t — the message header (unchanged)
uint8_t[] — the receive data in the buffer

The i2c_recv_t structure is defined as:

typedef struct {
    i2c_addr_t slave;  /* slave address */
    uint32_t   len;    /* length of receive data in bytes */
    uint32_t   stop;   /* send stop when complete? (0=no, 1=yes) */
} i2c_recv_t;

If an error occurs, the command returns:

EIO: The master send failed. Causes include: bad slave address, bad bus speed, bus is busy.
EINVAL: Bad message format.
ENOMEM: Insufficient memory.
EPERM: The master is locked by another connection.