ref: 53fa826a8a695bcfade5c47f636f719c71e96b98
dir: /sys/src/cmd/aux/icanhasmsi.c/
#include <u.h> #include <libc.h> int pcicfg16r(int fd, ushort *s, vlong offset) { char buf[2]; if(pread(fd, buf, 2, offset) < 2) return -1; *s = buf[0] | (buf[1] << 8); return 0; } void main() { int fd; long n; Dir *dir; char *p, *s; uchar cap, c; ushort sh; fd = open("/dev/pci", OREAD); if(fd < 0) sysfatal("open /dev/pci: %r"); n = dirreadall(fd, &dir); if(n < 0) sysfatal("dirreadall /dev/pci: %r"); close(fd); for(; n--; dir++) { p = dir->name + strlen(dir->name) - 3; if(strcmp(p, "raw") != 0) continue; s = smprint("/dev/pci/%s", dir->name); fd = open(s, OREAD); if(fd < 0) { fprint(2, "open %s: %r", s); free(s); continue; } if(pcicfg16r(fd, &sh, 0) < 0) goto err; if(sh == 0xFFFF) goto end; if(pcicfg16r(fd, &sh, 0x06) < 0) goto err; if((sh & (1<<4)) == 0) goto end; cap = 0x33; for(;;) { if(pread(fd, &cap, 1, cap+1) < 0) goto err; if(cap == 0) goto end; if(pread(fd, &c, 1, cap) < 0) goto err; if(c == 0x05) break; } s[strlen(s) - 3] = 0; print("%s\n", s+9); goto end; err: fprint(2, "read %s: %r", s); end: free(s); close(fd); } }