CLINT Datasheet

中文说明

Overview

The clint(core-local interruptor) IP is a fully parameterised soft IP implementing the RISCV Privilege Specification v1.1 compatible CLINT. The IP features an APB4 slave interface, fully compliant with the AMBA APB Protocol Specification v2.0.

Feature

• 64-bit programmable mtime and mtimecmp counter
• Software interrupt support
• Static synchronous design
• Full synthesizable

Interface

port name	type	description
apb4	interface	apb4 slave interface
clint ->	interface	clint slave interface
clint.tmr_irq_o	output	timer irq ouput
clint.sfr_irq_o	output	software irq ouput

Register

name	offset	length	description
MSIP	0x0	4	machine mode software interrupt
MTIMECMPL	0x4000	4	machine timer compare low
MTIMECMPH	0x4004	4	machine timer compare high
MTIMEL	0xbff8	4	machine timer low
MTIMEH	0xbffc	4	machine timer high

Machine Mode Software Interrupt

bit	access	description
[31:1]	none	reserved
[0:0]	RW	MSIP

reset value: 0x0000_0000

• MSIP: this bit is reflected in MSIP of the mip CSR. A machine-level software interrupt for a HART is pending or cleared by writing 1 or 0 respectively to the corresponding this MSIP bit

Machine Timer Low

bit	access	description
[31:0]	RO	MTIMEL

reset value: 0x0000_0000

• MTIMEL: the low 32-bit of 64-bit mtime CSR register

Machine Timer High

bit	access	description
[31:0]	RO	MTIMEH

reset value: 0x0000_0000

• MTIMEH: the high 32-bit of 64-bit mtime CSR register

Machine Timer Compare Low

bit	access	description
[31:0]	RW	MTIMECMPL

reset value: 0xFFFF_FFFF

• MTIMECMPL: the low 32-bit of 64-bit mtimecmp CSR register

Machine Timer Compare High

bit	access	description
[31:0]	RW	MTIMECMPH

reset value: 0xFFFF_FFFF

• MTIMECMPH: the high 32-bit of 64-bit mtimecmp CSR register

Program Guide

The software operation of clint is simple. These registers can be accessed by 4-byte aligned read and write. the C-like pseudocode of the timer interrupt operation:

clint.MTIMECMPL = MTIMECMP_LOW_32_bit  // write low 32-bit mtimecmp register
clint.MTIMECMPH = MTIMECMP_HIGH_32_bit // write high 32-bit mtimecmp register
... // some codes

// === mtime interrupt handle start ===
// add new value to the mtime interrupt
clint.MTIMECMPL = UPDATE_DELTA_VALUE & 0x0000FFFF
clint.MTIMECMPH = UPDATE_DELTA_VALUE & 0xFFFF0000
// === mtime interrupt handle end ===

... // some codes

software interrupt operation:

clint.MSIP = 1 // trigger software interrupt
... // some codes

// === software interrupt handle start ===
clint.MSIP = 0 // clear the software interrupt
// === software interrupt handle end ===

... // some codes

The trimmed reference keeps the RTL interface example only; it does not include a standalone CLINT software driver.

Resoureces

References

Revision History