struct i2c_timings — I2C timing information
struct i2c_timings {
u32 bus_freq_hz;
u32 scl_rise_ns;
u32 scl_fall_ns;
u32 scl_int_delay_ns;
u32 sda_fall_ns;
}; the bus frequency in Hz
time SCL signal takes to rise in ns; t(r) in the I2C specification
time SCL signal takes to fall in ns; t(f) in the I2C specification
time IP core additionally needs to setup SCL in ns
time SDA signal takes to fall in ns; t(f) in the I2C specification