driver-api/i3c/protocol.rst

1 .. SPDX-License-Identifier: GPL-2.0
17 https://resources.mipi.org/mipi-i3c-v1-download).
22 The I3C (pronounced 'eye-three-see') is a MIPI standardized protocol designed
25 while remaining power-efficient.
42 I3C is a multi-master protocol, so there might be several masters on a bus,
46 Each device on the I3C bus has to be assigned a dynamic address to be able to
51 In addition to these per-device addresses, the protocol defines a broadcast
54 Once a dynamic address has been assigned to a device, this address will be used
56 assigned a dynamic address, the device should still process broadcast messages.
65 The discovery mechanism is called DAA (Dynamic Address Assignment), because it
66 not only discovers devices but also assigns them a dynamic address.
70 * BCR: Bus Characteristic Register. This 8-bit register describes the device bus
72 * DCR: Device Characteristic Register. This 8-bit register describes the
74 * Provisioned ID: A 48-bit unique identifier. On a given bus there should be no
89 dynamic address the higher the priority).
95 I3C Hot-Join
98 The Hot-Join mechanism is similar to USB hotplug. This mechanism allows
107 device joined the bus and is waiting for a dynamic address.
110 assign a dynamic address to the slave.
122 ----------------
127 CCC commands contain an 8-bit CCC ID describing the command that is executed.
141 Note that vendors can use a dedicated range of CCC IDs for their own commands
142 (0x61-0x7f and 0xe0-0xef).
145 -------------------------
148 device specific and does not require high transfer speed.
151 passed the device address (dynamic address assigned during DAA), a payload
158 ----------------
161 high transfer speed.
167 * HDR-DDR: Double Data Rate mode
168 * HDR-TSP: Ternary Symbol Pure. Only usable on busses with no I2C devices
169 * HDR-TSL: Ternary Symbol Legacy. Usable on busses with I2C devices
176 * one 16-bits command word in big endian
177 * N 16-bits data words in big endian
179 Those words may be wrapped with specific preambles/post-ambles which depend on
183 The 16-bits command word is made of:
189 * bit[0]: reserved/parity-bit