Overview

Welcome to the Board Support Package (BSP) for the Efinix Sapphire SoC. This BSP allows software running on the RISC-V processor to interact with on-chip peripherals such as SPI, I2C, GPIO, and Timers.

The drivers are designed to be bare-metal compliant, lightweight, and capable of running with or without an operating system (RTOS).

Driver Implementation Model

The BSP follows an Instance-Based driver model. Each peripheral driver consists of two main data structures:

• Hardware Register Map (*_hwreg_t): A structure that maps directly to the physical memory address of the peripheral. This is typically used internally by the driver to read/write hardware registers.
• Software Instance (*_instance_t): A high-level structure that holds the Configuration State (Shadow Registers) and a pointer to the hardware base address. @ Unlike traditional drivers that write to hardware immediately, this BSP uses a "Configure-then-Apply" pattern to ensure atomic updates:

1. Modify: Update the settings in the instance structure (e.g., spi.cpol = HIGH).
2. Apply: Call the applyConfig() function to flush these settings to the hardware.

Initialization Sequence

To use a specific driver, the application must follow this initialization flow:

1. Instantiate: Declare the driver instance structure.
2. Link: Assign the hardware base address (defined in soc.h).
3. Configure: Set the desired parameters (Prescalers, Modes, Interrupts).
4. Apply: Call *_applyConfig() to initialize the hardware.
5. Enable: (Optional) Register the interrupt handler via the PLIC.

Note: This is an example showing how to instantiate I2C with i2c_instance_t and i2c_hwreg_t.

#include i2c/i2c.h
 
#define I2C_FREQ             100000
#define I2C_ADDR             0x67<<1   // Slave device address
#define I2C_CTRL_HZ          SYSTEM_CLINT_HZ
#define I2C_CTRL             (i2c_hwreg_t *)SYSTEM_I2C_1_IO_CTRL
 
i2c_instance_t I2C_inst = {
      .hwreg                  = I2C_CTRL,
      .slaveAddress           = I2C_ADDR,
      .samplingClockDivider   = 3,
      .timeout                = I2C_CTRL_HZ/1000,
      .tsuDat                 = I2C_CTRL_HZ/(I2C_FREQ*5),
      .tLow                   = I2C_CTRL_HZ/(I2C_FREQ*2),
      .tHigh                  = I2C_CTRL_HZ/(I2C_FREQ*2),
      .tBuf                   = I2C_CTRL_HZ/(I2C_FREQ),
};

Revision History

Version	Date	Author	Description of Changes
1.0.1	2026-02-25	Efinix	Critical Update: Added spi_instance_t.
1.0.0	2026-02-01	Efinix	Initial BSP release. Includes drivers for I2C Driver, SPI Driver, UART Driver, and GPIO Driver.

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