TIMER

Introduction

RK3399 has 12 Timers (timer0-timer11), 12 SecureT imers
(stimer0~stimer11) and 2 Timers (pmutimer0~pmutimer1), we mainly use
the Timers (timer0-timer11) clock frequency is 24MHZ, the working mode
has

free-running

 and

user-defined count

 mode.

The framework


Working mode

User-defined count :

 Timer loads the initial value to registers

TIMERn_LOAD_COUNT3

 and

TIMER_LOADn_COUNT2

. When the time accumulative value is in registers

TIMERn_LOAD_COUNT1

 and

TIMERn_LOAD_COUNT0

, it will not be loaded into the counting register automatically. The
user needs to re-close the counter and then reset the counter to
continue working.

Free-running :

 Timer loads the initial value into registers

TIMER_LOAD_COUNT3

 and

TIMER_LOAD_COUNT2

. When the time accumulative value is in registers

TIMERn_LOAD_COUNT1

 and

TIMERn_LOAD_COUNT0

, Timer will always automatically load the count register.

Software configuration

1 .

 Defined in DTS files associated with the Timer configuration:

kernel/arch/arm64/boot/dts/rockchip/rk3399.dtsi

   rktimer: rktimer@ff850000 {
       compatible = "rockchip,rk3399-timer";
       reg = <0x0 0xff850000 0x0 0x1000>;
       interrupts = <GIC_SPI 81 IRQ_TYPE_LEVEL_HIGH 0>;
       clocks = <&cru PCLK_TIMER0>, <&cru SCLK_TIMER00>;
       clock-names = "pclk", "timer";
   };

Where defined

Timer0

 register and interrupt number and clock etc

The interrupt Numbers for other Timers are shown in the picture below


2 .

 Corresponding driver files :

Kernel/drivers/clocksource/rockchip_timer.c

Corresponding registers and usage

1 .

 Register picture below


2 .

 Use mode, view the corresponding register

   root@rk3399_firefly_box:/ # io -4 0xff85001c  //View the status of the current control register                                 
   ff85001c:  00000007 
    
   root@rk3399_firefly_box:/ # io -4 0xff850000  //Check the current value of the register                                
   ff850000:  0001639f

Control corresponding register:

   root@rk3399_firefly_box:/ # io -4 -w 0xff85001c 0x06  //Turn off time counting