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/* wpr2_reset - clear GPU WPR2 registers via BAR0 MMIO to unstick GSP boot.
*
* When nvidia.ko is unloaded, GSP firmware can remain resident in WPR2
* (write-protected region 2 in FB). The next RmInitAdapter then fails with
* "unexpected WPR2 already up". FLR does not clear WPR2; only a cold (power)
* reset does. This tool pokes WPR2_ADDR_LO/HI to zero directly through
* /sys/bus/pci/devices/<dev>/resource0 while no driver is bound.
*
* Usage: sudo ./wpr2_reset [pci.bdf] (default 0000:01:00.0)
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#define NV_PFB_PRI_MMU_WPR2_ADDR_LO 0x1fa824
#define NV_PFB_PRI_MMU_WPR2_ADDR_HI 0x1fa828
int main(int argc, char **argv)
{
const char *bdf = argc > 1 ? argv[1] : "0000:01:00.0";
char path[256];
snprintf(path, sizeof(path), "/sys/bus/pci/devices/%s/resource0", bdf);
int fd = open(path, O_RDWR | O_SYNC);
if (fd < 0) { perror(path); return 1; }
void *bar = mmap(NULL, 0x200000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (bar == MAP_FAILED) { perror("mmap"); return 1; }
volatile uint32_t *lo = (volatile uint32_t *)((char *)bar + NV_PFB_PRI_MMU_WPR2_ADDR_LO);
volatile uint32_t *hi = (volatile uint32_t *)((char *)bar + NV_PFB_PRI_MMU_WPR2_ADDR_HI);
printf("before: WPR2_ADDR_LO=0x%08x WPR2_ADDR_HI=0x%08x\n", *lo, *hi);
*lo = 0;
*hi = 0;
/* read back */
printf("after : WPR2_ADDR_LO=0x%08x WPR2_ADDR_HI=0x%08x\n", *lo, *hi);
if (*hi == 0)
printf("WPR2 cleared - driver load should now boot GSP cleanly\n");
else
printf("write dropped (PLM?) - WPR2 still up\n");
munmap(bar, 0x200000);
close(fd);
return *hi ? 1 : 0;
}
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