Zephyr AXI IIC Driver Support

This page gives an overview of the AXI IIC Zephyr driver which is available as part of the zephyr-amd repo.

HW Features

  • AXI I2C controller

Design Notes

  • N/A

Implementation

Features Supported

  • Master operation

  • Slave operation

  • Repeated Start.

  • Interrupt driven.

  • 7-bit addressing

  • Transmit and receive FIFOs — 16 bytes.

  • Dynamic Receive as a master

  • APIs supported

    • i2c_configure - Configure operation of a host controller

    • i2c_transfer - Perform data transfer to another I2C device in controller mode

      • synchronous transfer

    • i2c_target_register - Registers the provided config as Target device of a controller

    • i2c_target_unregister - Unregisters the provided config as Target device

Missing Features

  • Dynamic Send as a master

  • Multi-master operation.

  • 10-bit addressing.

  • Polled operation.

  • APIs not supported

    • i2c_get_config - Get configuration of a host controller

    • i2c_transfer_cb - Perform data transfer to another I2C device in controller mode

      • asynchronously with a callback completion

    • i2c_iodev_submit - Submit requests to an I2C device with RTIO

    • i2c_recover_bus - Recover the I2C bus

Known Issues

  • N/A

Limitations

  • N/A

Kernel Configuration

CONFIG_I2C=y

The following configuration is also supported:

CONFIG_I2C_TARGET

  • CONFIG_I2C_TARGET (Slave Mode Support)

Device Tree

axi_i2c0: i2c@a0000000 {
    compatible = "xlnx,xps-iic-2.00.a";
    #address-cells = <1>;
    #size-cells = <0>;
    status = "disabled";
    interrupts = <GIC_SPI 89 IRQ_TYPE_LEVEL
                  IRQ_DEFAULT_PRIORITY>;
    reg = <0xa0000000 0x1000>;
    interrupt-parent = <&gic>;
};

  • changes with respect to Linux device tree

    • clocks property is not added

  • Lopper changes are added to generate axi-iic node

Driver Stack Size

  • 2.1 KB (Master + Slave)

    • 1.5 KB (Master Only)

    • 3.0 KB (Master + Slave + Debug Log)

Test Platform

  • zcu102 - ZynqMp

Test SoC Architecture

  • R5

Testing Sequence

  • Build zephyr application for R5 core

    • west build -p -b <board> <sample application path>

  • Run zephyr elf on board

Example Tests

Test Name

Example Source

Description

I2C custom target example

samples/drivers/i2c/custom_target

Setup Custom I2C Target on the I2C Interface

I2C target example

samples/drivers/i2c/target_eeprom

Setup I2C Target on the I2C Interface

EEPROM sample

samples/drivers/eeprom/

Modified for target specific

zcu102 - zephyr_zcu102_axi_iic_samples_drivers_eeprom.c (download)

EEPROM Write and Read Sample using I2C Driver API

AXI-I2C Master Mode Example

zcu102 r5 - zephyr_zcu102_r5_axi_i2c_master.c (download)

Master Mode Write, Read, Repeated Start, Dynamic Read.

  • Requires I2C Mux connected as slave

    • HW Specific MUX addr, MUX channel.

Expected Output

  • R5: zcu102 test log:

    • zcu102 R5 AXI-I2C master log
      I: Configuring i2c@a0000000 at 0xa0000000
D: Controller reinit
I: initialized
I: Configuring i2c@a0010000 at 0xa0010000
D: Controller reinit
I: initialized
*** Booting Zephyr OS build a1e5b441f39a ***
I: AXI-I2C: master: init: Start
I: AXI-I2C: master: device READY
I: AXI-I2C: master: init: PASSED
I: AXI-I2C: master: write: Start
I: AXI-I2C: master: write: I2C_MUX_ADDR: Progress
I: AXI-I2C: master: write: data: 01h
D: Controller reinit
D: Set IER to 0x17
D: ISR called for 0xa0010000, status 0x10
D: Got ISR events 0x10
I: AXI-I2C: master: write: I2C_MUX_ADDR success
I: AXI-I2C: master: write: PASSED
I: AXI-I2C: master: read: Start
I: AXI-I2C: master: read: I2C_MUX_ADDR Progress
D: Controller reinit
D: Set IER to 0x09
D: ISR called for 0xa0010000, status 0x08
D: Got ISR events 0x08
D: Set IER to 0x11
D: ISR called for 0xa0010000, status 0x10
D: Got ISR events 0x10
I: AXI-I2C: master: read: I2C_MUX_ADDR success
I: AXI-I2C: master: read: data: 01h 01h 01h
I: AXI-I2C: master: read: PASSED
I: AXI-I2C: master: write-read-repeated-start: Start
I: AXI-I2C: master: write-read-repeated-start: IIC-Mux Progress
I: AXI-I2C: master: write-repeated-start: data: 01h
D: Controller reinit
D: Set IER to 0x17
D: ISR called for 0xa0010000, status 0x04
D: Got ISR events 0x04
D: Set IER to 0x1b
D: ISR called for 0xa0010000, status 0x0a
D: Got ISR events 0x08
D: Set IER to 0x11
D: ISR called for 0xa0010000, status 0x10
D: Got ISR events 0x10
I: AXI-I2C: master: write-read-repeated-start: IIC-Mux success
I: AXI-I2C: master: write-read-repeated-start: read data: 01h
I: AXI-I2C: master: write-read-repeated-start: PASSED
I: AXI-I2C: master: mode-test completed, PASSED

    • Download zephyr_zcu102_r5_axi_i2c_master.log

Code Coverage

Performance Metric

  • TBA

Mainline Status

  • The preceding features are mainlined as of 01-Dec-2024

Driver Source Path

  • drivers/i2c/i2c_xilinx_axi.c

Misra C Report

  • Per coding guidelines of zephyr

  • Detailed Breakup

misra-c rule (Zephyr guideline)

Severity

Actual File Violations

Kernel Utility Violations

Dir 4.6

Advisory

18

0

Dir 4.8

Advisory

0

7

Dir 4.9

Advisory

0

1

Rule 1.2

Advisory

0

16

Rule 2.7

Advisory

2

0

Rule 5.9

Advisory

0

1

Rule 12.1

Advisory

6

10

Rule 13.3

Advisory

2

0

Rule 10.1

Required

175

0

Rule 10.3

Required

14

0

Rule 10.4

Required

126

0

Rule 10.6

Required

1

0

Rule 10.7

Required

4

0

Rule 11.9

Required

4

0

Rule 13.5

Required

1

0

Rule 14.3

Required

0

7

Rule 14.4

Required

33

0

Rule 15.7

Required

2

0

Rule 17.7

Required

10

0

Rule 21.2

Required

0

6

Total violations

398

48