blob: 4881ba3ccb7fba83fb01e70b086cd48851bbe485 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
/***************************************************************************
* Copyright (c) 2026 10xEngineers
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
#include "tx_port.h"
#include "csr.h"
#include "hwtimer.h"
/*
* SBI legacy set_timer ecall
*
* EID (a7) = 0 (SBI_SET_TIMER)
* a0 = absolute mtime compare value
*
* Programs mtimecmp for the current hart and clears sip.STIP.
*/
static inline void sbi_set_timer(uint64_t stime_value)
{
register uint64_t a0 asm("a0") = stime_value;
register uint64_t a7 asm("a7") = 0; /* SBI_SET_TIMER */
asm volatile("ecall"
: "+r"(a0)
: "r"(a7)
: "memory");
}
/*
* Read the free-running mtime counter via the rdtime pseudo-instruction.
* Accessible from S-mode per RISC-V Priv Spec §10.1 (Zicntr extension).
*/
static inline uint64_t read_time(void)
{
uint64_t t;
asm volatile("rdtime %0" : "=r"(t));
return t;
}
int hwtimer_init(void)
{
uint64_t now = read_time();
sbi_set_timer(now + TICKNUM_PER_TIMER);
return 0;
}
int hwtimer_handler(void)
{
uint64_t now = read_time();
sbi_set_timer(now + TICKNUM_PER_TIMER);
return 0;
}
|
