GNU C中嵌入汇编添加一个自定义uboot命令

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"
);