pwr_info
typedef struct pwr_info pwr_info_t;
p->next = pwr_p->pwr_info;
pwr_p->pwr_info = p;
for (prev_infop = &pwr_p->pwr_info; *prev_infop != NULL;
for (p = pwr_p->pwr_info; p != NULL; p = p->next) {
pci_pwr_chld_t *pwr_info; /* linked list of children */