CV184x DeviceDriverUse

Revision History

Revision	Date	Description
1.0.0	2025/03/12	Initial version
1.0.1	2025/07/08	Add CVI_PINMUX_Operation_Guide
1.0.2	2026/04/28	Update PWM/ADC/I2C/SPI/GPIO/UART/Watchdog operation guides

Contents

• 1. Disclaimer
• 2. Ethernet Operation Guide
  • 2.1. Operation Example
  • 2.2. IPv6Description
  • 2.3. IEEE 802.3xFlow Control
    • 2.3.1. Flow Control Description
    • 2.3.2. Flow Control Configuration
    • 2.3.3. ethtoolConfigure Flow Control Through the Interface
• 3. USBOperation Guide
  • 3.1. Preparation
  • 3.2. UbootOperation Procedure
    • 3.2.1. UbootunderUSB HostConfiguration
    • 3.2.2. UbootunderU
  • 3.3. linux Host
    • 3.3.1. USB 2.0 Host Operation Procedure
  • 3.4. linux Device
    • 3.4.1. Preparation
    • 3.4.2. Switch GPIO
    • 3.4.3. Device is DeviceofOperation Guide
    • 3.4.4. Device isTerminalDeviceofOperation Guide
    • 3.4.5. Device is ADB DeviceofOperation Guide
    • 3.4.6. Device is RNDIS DeviceofOperation Guide
  • 3.5. Issues to Note During Operation
• 4. SD/MMC Card Operation Guide
  • 4.1. Preparation
  • 4.2. Operation Procedure
  • 4.3. Operation Example
    • 4.3.1. U-Boot SD Card Operations
    • 4.3.2. Linux SD Card Operations
  • 4.4. Issues to Note During Operation
• 5. I2C Operation Guide
  • 5.1. Preparation
    • 5.1.1. Pin（willPin Multiplexingto I2C Function）
  • 5.2. Operation Procedure
  • 5.3. InterfaceRateSettingsDescription
  • 5.4. I2C Read/Write Command Example (i2c-tools)
  • 5.5. GPIO Simulate I2C (using I2C-2 as an example)
  • 5.6. I2C Recovery Configuration Description
  • 5.7. Kernel space I2C Read/writeProgramExample
  • 5.8. User-Space I2C Read/Write Program Example
• 6. SPI Operation Guide
  • 6.1. Preparation
    • 6.1.1. EnableKernel SPI and DMA Configuration
    • 6.1.2. Enable SPI1 in the Device Tree
    • 6.1.3. SPI1 Pin Switching
  • 6.2. Operation Procedure
  • 6.3. SPI Loopback Test
  • 6.4. Operation Example
  • 6.5. Kernel-Space SPI Read/Write Program Example
  • 6.6. User-Space SPI Read/Write Program Example
• 7. GPIOOperation Guide
  • 7.1. Preparation
  • 7.2. Operation Flow
  • 7.3. Operation Example
    • 7.3.1. GPIOCommand-Line Operation Example
    • 7.3.2. Kernel-Space GPIO Operation Example
      • 7.3.2.1. Header Files and Macro Definitions
      • 7.3.2.2. Interruptcallback function
      • 7.3.2.3. Module Initialization (GPIO Read/Write + Interrupt Registration)
      • 7.3.2.4. Module Unload (Resource Release)
      • 7.3.2.5. Module Declaration
    • 7.3.3. User-Space GPIO Operation Example
• 8. UART Operation Guide
  • 8.1. Preparation
    • 8.1.1. Kernel Requirements
    • 8.1.2. Enable UART in the device tree
    • 8.1.3. UART Use DMA ofDevice TreeConfiguration
    • 8.1.4. Pin Multiplexing
  • 8.2. Operation Flow
    • 8.2.1. UART Loopback Test
    • 8.2.2. UART Serial Communication (Terminal Transmit/Receive)
  • 8.3. UART Extended Operations（Common / / Advanced）
    • 8.3.1. Common Extended Operations（Basic Function Supplement）
    • 8.3.2. Troubleshooting Operations（Resolve Serial Port Problems）
    • 8.3.3. AdvancedConfigurationOperation（Adaptation to Special Scenarios）
    • 8.3.4. UART Summary of Extended Operations
  • 8.4. UART Output at a Specific Baud Rate (3M Example)
  • 8.5. User-Space Program Development Example
• 9. Watchdog Operation Guide
  • 9.1. Preparation
  • 9.2. Operation Flow
  • 9.3. Operation Example
    • 9.3.1. Enable Watchdog and feed it immediately
    • 9.3.2. Set the timeout
    • 9.3.3. Feed the Dog (Keepalive)
    • 9.3.4. Get the current timeout
    • 9.3.5. Get the remaining time
    • 9.3.6. Disable Watchdog（Magic Close）
    • 9.3.7. CompleteUser-Space Program Example
    • 9.3.8. Quick Command-Line Example
• 10. PWM Operation Guide
  • 10.1. Preparation
  • 10.2. Operation Flow
  • 10.3. Operation Example
    • 10.3.1. Command-Line Operation Example
    • 10.3.2. Maximum and Minimum Frequency Operation Example
    • 10.3.3. User-Space Program Example
    • 10.3.4. Run Mode Description
• 11. ADC Operation Guide
  • 11.1. Preparation
  • 11.2. Operation Flow
  • 11.3. Operation Example
    • 11.3.1. Read SARADC0 channel 1 and convert it to voltage
    • 11.3.2. SARADC0 Read example for channel 3 and RTC_SARADC0 channel 10
    • 11.3.3. Kernel space ADC Read/writeExample
    • 11.3.4. User-Space ADC Read/Write Example
• 12. CVI PINMUX Operation Guide
  • 12.1. Preparation
  • 12.2. Operation Flow
    • 12.2.1. U-Boot under Pinmux Configuration
    • 12.2.2. Kernelunder Pinmux Configuration（cvi_pinmux Tools）
  • 12.3. ephy Switch Pins to GPIO or SPI
    • 12.3.1. Switch to GPIO
    • 12.3.2. Switch to SPI
• 13. DMA Operation Guide
  • 13.1. dev-to-memOperation Guide
    • 13.1.1. Kernel Requirements
    • 13.1.2. DriverDescription
  • 13.2. mem-to-memOperation Guide
    • 13.2.1. Configure and open kernel menuconfig
    • 13.2.2. Build the kernel (including modules)
    • 13.2.3. LoadandDeviceNode
  • 13.3. User-Space Test
    • 13.3.1. Complete Test Code
    • 13.3.2. Build Description
    • 13.3.3. Test Content Description
  • 13.4. ioctl Interface
  • 13.5. How to Verify DMA mem-to-mem
    • 13.5.1. View Kernel Logs
    • 13.5.2. View CPU Usage
• 14. Thermal Control Strategy and Test Operation Guide
  • 14.1. Preparation
  • 14.2. Operation Flow
    • 14.2.1. View CPU/TPU clocks
    • 14.2.2. View the current temperature
    • 14.2.3. Thermal Control Strategy（and trip Correspondence）
    • 14.2.4. Hysteresis Description
  • 14.3. Operation Example
    • 14.3.1. Simulated Temperature Test Steps
    • 14.3.2.
    • 14.3.3. Simulate 90°C (should enter the first throttling level)
    • 14.3.4. Simulate 100°C (should enter the second throttling level)
    • 14.3.5. Simulate a drop to 95°C (with hysteresis, the frequency should remain at the second level)
    • 14.3.6. Simulate a drop to 94°C (below the hysteresis exit threshold; it should return to the first or a higher level, depending on the policy)
    • 14.3.7. Simulate 120°C (trigger critical and force shutdown)
    • 14.3.8. Modify Thermal Thresholds, Shutdown Temperature, and Hysteresis in the Device Tree
    • 14.3.9. Board-Level Override Example
  • 14.4. Related File Index