查看“I2C internal peripheral”的源代码

== Article purpose ==
The purpose of this article is to:
* briefly introduce the I2C peripheral and its main features
* indicate the level of security supported by this hardware block
* explain how each instance can be allocated to the three runtime contexts and linked to the corresponding software components
* explain, when necessary, how to configure the I2C peripheral.

==Peripheral overview==
The I2C bus interface serves as an interface between the microcontroller and the serial I2C bus.<br>
It provides multi-master capability, and controls all I2C bus-specific sequencing, protocol, arbitration and timing.<br>
The I2C controller allows to be a slave as well if need be.<br>
It is also SMBus 2.0 compatible.
<br />
For more information about I2C please refer to this link: '''I2C wikipedia'''<ref name="I2C">http://en.wikipedia.org/wiki/I2C</ref> or '''i2c-bus.org'''<ref name="I2C specification">https://www.i2c-bus.org/specification/</ref><br>
For more information about SMBus please refer to this link: '''SMBus wikipedia'''<ref name="Wiki SMBus">https://en.wikipedia.org/wiki/System_Management_Bus</ref> or '''i2c-bus.org'''<ref name="SMBus">https://www.i2c-bus.org/smbus/</ref>

===Features===
Here are the main features:
* Multi-master
* Standard (100 KHz) and fast speed modes (400 KHz and Plus 1 MHz)
* I2C 10-bit address
* I2C slave capabilities (programmable I2C address)
* DMA capabilities
* SMBus 2.0 compatible
** Standard bus protocol (quick command; byte, word, block read/write)
** Host notification
** Alert

Refer to the [[STM32MP15 resources#Reference manuals|STM32MP15 reference manuals]] for the complete list of features, and to the software components, introduced below, to see which features are implemented.

===Security support===
* There are six I2C instances. <br>
**I2C instances 1, 2, 3 and 5 are '''non-secure'''.
**I2C instances 4 and 6 can be '''secure''' (under [[ETZPC_internal_peripheral|ETZPC]] control).

==Peripheral usage and associated software==
===Boot time===
The I2C peripheral is usually not used at boot time. But it may be used by the SSBL and/or FSBL (see [[Boot chain overview]]), for example, to configure a PMIC (see [[PMIC hardware components]]), or to access data stored in an external EEPROM.

===Runtime===
====Overview====
I2C4&6 instances can be allocated to:
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 secure core to be controlled in OP-TEE by the [[OP-TEE_overview|OP-TEE I2C driver]]
All I2C instances can be allocated to:
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-A7 non-secure core to be controlled in U-Boot or Linux<sup>&reg;</sup> by the [[I2C overview|I2C framework]]
All but I2C4&6 instances can be allocated to:
* the Arm<sup>&reg;</sup> Cortex<sup>&reg;</sup>-M4 to be controlled in STM32Cube MPU Package by [[STM32CubeMP1 architecture|STM32Cube I2C driver]]

Chapter [[#Peripheral assignment|Peripheral assignment]] describes which peripheral instance can be assigned to which context.

====Software frameworks====
{{:Internal_peripherals_software_table_template}}
 | Low speed interface
 | [[I2C internal peripheral|I2C]]
 | [[OP-TEE_overview|OP-TEE I2C driver]]
 | [[I2C overview| I2C Engine framework]]
 | [[STM32CubeMP1 architecture|STM32Cube I2C driver]]
 |
 |-
 |}

====Peripheral configuration====
The configuration is applied by the firmware running in the context to which the peripheral is assigned. The configuration can be done alone via the [[STM32CubeMX]] tool for all internal peripherals, and then manually completed (particularly for external peripherals), according to the information given in the corresponding software framework article.

For Linux<sup>&reg;</sup> kernel configuration, please refer to [[I2C overview#Configuration|I2C configuration]].

Please refer to [[I2C device tree configuration]] for detailed information on how to configure I2C peripherals.

====Peripheral assignment====
{{:Internal_peripherals_assignment_table_template}}
<onlyinclude>
 | rowspan="6" | Low speed interface
 | rowspan="6" | [[I2C internal peripheral|I2C]]
 | I2C1
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | I2C2
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | I2C3
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | I2C4
 | <span title="assignable peripheral" style="font-size:21px">☐</span> 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 |
 | Assignment (single choice). <br />Used for PMIC control on [[:Category:Getting_started_with_STM32MP1_boards|ST boards]].
 |-
 | I2C5
 | 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 | Assignment (single choice)
 |-
 | I2C6
 | <span title="assignable peripheral" style="font-size:21px">☐</span> 
 | <span title="assignable peripheral" style="font-size:21px">☐</span>
 |
 | Assignment (single choice)
 |-
</onlyinclude>
 |}

==References==
<references/>