nixos-riscv/tools/plictool.c

/* Copyright (c) 2024 Barcelona Supercomputing Center (BSC)
 * SPDX-License-Identifier: MIT
 * Author: Rodrigo Arias Mallo <rodrigo.arias@bsc.es> */

/* Small utility to dump the state of the PLIC. */

/* Changelog:
 *   v0.0.1 (2024-09-03): Initial version.
 *   v0.0.2 (2024-09-04): Print contexts in another line and on/off information.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <errno.h>

const char *plic_address_str = "0x40800000";
long ncontexts = 15872L;
long maxsources = 1024L;
long nsources = 1024L;

static void
usage(void)
{
	printf("plictool v0.0.2 - Rodrigo Arias Mallo <rodrigo.arias@bsc.es>\n");

	printf(
"Usage: plictool [-a addr] [-s nsources] [-c ncontexts]\n");
	exit(1);
}

void dump_sources(void *base)
{
	for (long s = 0; s < nsources; s++) {
		int printed_source = 0;

		uint32_t *pending_reg  = base + 0x1000L + (s / 32L) * 4L;
		long shift = s % 32L;
		uint32_t pending = ((*pending_reg) >> shift) & 1;
		uint32_t *priority_reg = base + 0x0000L + (s * 4L);
		uint32_t priority = *priority_reg;

		const char *fmt =
			"src=%ld pend=%u prio=%u\n";

		if (pending || priority) {
			printf(fmt, s, pending, priority);
			printed_source = 1;
		}

		int first_context = 1;
		for (long c = 0; c < ncontexts; c++) {
			uint32_t *enable_reg = base + 0x2000L + 0x80L * c + (s / 32L) * 4L;
			uint32_t enabled = ((*enable_reg) >> shift) & 1;
			uint32_t *threshold_reg = base + 0x200000L + (c * 0x1000L);
			uint32_t threshold = *threshold_reg;

			if (!enabled)
				continue;

			if (!printed_source) {
				printf(fmt, s, pending, priority);
				printed_source = 1;
			}

			int active = priority > threshold ? 1 : 0;

			printf("  ctx=%ld thre=%u active=%d\n", c, threshold, active);
		}
	}
}

int main(int argc, char *argv[])
{
	int opt;

	while ((opt = getopt(argc, argv, "a:hs:c:")) != -1) {
		switch (opt) {
			case 'a':
				plic_address_str = optarg;
				break;
			case 's':
				nsources = atol(optarg);
				break;
			case 'c':
				ncontexts = atol(optarg);
				break;
			case 'h':
			default: /* '?' */
				usage();
		}
	}

	off_t plic_address = (off_t) strtoll(plic_address_str, NULL, 16);

	printf("plic=0x%08x nsources=%ld ncontexts=%ld\n",
			plic_address, nsources, ncontexts);

	int fd = open("/dev/mem", O_RDWR | O_SYNC);

	if (fd == -1) {
		perror("cannot open /dev/mem");
		exit(1);
	}

	size_t map_size = 0x4000000UL;
	void *map_base = mmap(0, map_size, PROT_READ | PROT_WRITE, MAP_SHARED,
			fd, plic_address);

	if (map_base == MAP_FAILED) {
		perror("mmap failed");
		if (errno == EPERM) {
			fprintf(stderr,	"Have you disabled 'CONFIG_STRICT_DEVMEM' and "
					"'CONFIG_IO_STRICT_DEVMEM' in the kernel config?\n"
					"Hint: zgrep STRICT_DEVMEM /proc/config.gz\n");
		}
		exit(1);
	}

	dump_sources(map_base);

	munmap(map_base, map_size);

	close(fd);

	return 0;
}