二话没用，直接上代码：
#include <common.h> #include <command.h> /* static inline int __raw_readsb(unsigned int addr, void *data, int bytelen) { __asm__ __volatile__ ("1:ld.dir8, [r0]\n" "sub.fr2, r2, 1\n" "bnz.d1b\n" "stb.abr8, [r1, 1]\n" : : "r" (addr), "r" (data), "r" (bytelen) : "r8"); return bytelen; } static int disable_interrupts (void) { unsigned long old,temp; __asm__ __volatile__("mrs %0, cpsr\n" "orr %1, %0, #0x80\n" "msr cpsr_c, %1" : "=r" (old), "=r" (temp) : : "memory"); return (old & 0x80) == 0; } */ static void show_cache_state(void) { unsigned long state; __asm__ volatile ("MRC p15, 0,%0, c1, c0, 0\n\r" : "=r" (state) : : "memory" ); printf(" register SCTLR value: %lx \n", state ); if(state & (0x01<<12)) { printf("Icache : ON\n"); } else { printf("Icache : OFF\n"); } if(state & (0x01<<2)) { printf("Dcache : ON\n"); } else { printf("Icache : OFF\n"); } } U_BOOT_CMD(nu_cache, 1, 0, show_cache_state, "show Icache and Dcache state", "nu_cache [args...]\n"); static void do_set_cache(unsigned int icase) { unsigned long value,state; __asm__ volatile ("MRC p15, 0,%0, c1, c0, 0\n\r" : "=r" (state) : : "memory" ); printf(" register SCTLR old value: %lx \n", state ); switch (icase) { case 1: value = state & ~(0x01<<2); break; case 2: value = state | (0x01<<2); break; case 3: value = state & ~(0x01<<12); break; case 4: value = state | (0x01<<12); break; default: value = state; break; } printf(" the value will write to is: %#lx \n", value ); __asm__ volatile ("MCR p15, 0,%0, c1, c0, 0\n\r" : : "r" (value) : "memory" ); __asm__ volatile ("MRC p15, 0,%0, c1, c0, 0\n\r" : "=r" (state) : : "memory" ); printf(" register SCTLR new value: %lx \n", state ); } static int set_cache(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { if(argc < 3) { printf("args eeror\n"); return -1 ; } if( strcmp(argv[1],"-D")==0 ) { printf("set Dcache:"); if( strcmp(argv[2],"0")==0 ) { do_set_cache(1); } else if( strcmp(argv[2],"1")==0 ) { do_set_cache(2); } else { printf("argv[2] must is 0 or 1 \n"); return -1 ; } printf("\n"); } else if( strcmp(argv[1],"-I")==0 ) { printf("set Icache:"); if( strcmp(argv[2],"0")==0 ) { do_set_cache(3); } else if( strcmp(argv[2],"1")==0 ) { do_set_cache(4); } else { printf("argv[2] must is 0 or 1 \n"); return -1 ; } printf("\n"); } else { printf("argv[1] must be -D or -I\n"); return -1; } return 0; } U_BOOT_CMD(nu_cache_set, 3, 2, set_cache, "set Icache and Dcache ", "nu_cache_set [options]\n" );