1 #include <sys/types.h> 2 #include <minix/minlib.h> 3 4 void 5 read_tsc(u32_t *hi, u32_t *lo) 6 { 7 /* Read Clock Cycle Counter (CCNT). Intel calls it Time Stamp Counter (TSC) */ 8 u32_t ccnt; 9 10 /* Get value from the Performance Monitors Cycle Counter Register. 11 * See ARM Architecture Reference Manual B5.1.113. 12 */ 13 asm volatile ("MRC p15, 0, %0, c9, c13, 0\t\n" : "=r" (ccnt) : : "%0"); 14 15 /* The ARMv7-A clock cycle counter is only 32-bits, but read_tsc is 16 * expected to return a 64-bit value. hi is therefore always 0. 17 */ 18 *hi = 0; 19 *lo = ccnt; 20 } 21 22