The Timer/Counter Control Registers are registers to control timers and counters.

Timer/Counter Control Registers are defined in hardware/tools/avr/avr/include/avr/iom328p.h as below.

#define TCCR0A _SFR_IO8(0x24)
#define WGM00 0
#define WGM01 1
#define COM0B0 4
#define COM0B1 5
#define COM0A0 6
#define COM0A1 7

#define TCCR0B _SFR_IO8(0x25)
#define CS00 0
#define CS01 1
#define CS02 2
#define WGM02 3
#define FOC0B 6
#define FOC0A 7

#define TCCR1A _SFR_MEM8(0x80)
#define WGM10 0
#define WGM11 1
#define COM1B0 4
#define COM1B1 5
#define COM1A0 6
#define COM1A1 7

#define TCCR1B _SFR_MEM8(0x81)
#define CS10 0
#define CS11 1
#define CS12 2
#define WGM12 3
#define WGM13 4
#define ICES1 6
#define ICNC1 7

#define TCCR2A _SFR_MEM8(0xB0)
#define WGM20 0
#define WGM21 1
#define COM2B0 4
#define COM2B1 5
#define COM2A0 6
#define COM2A1 7

#define TCCR2B _SFR_MEM8(0xB1)
#define CS20 0
#define CS21 1
#define CS22 2
#define WGM22 3
#define FOC2B 6
#define FOC2A 7

They call _SFR_IO8() and _SFR_MEM8().