TIMER¶
Introduction¶
RK3399 has 12 Timers (timer0-timer11), 12 Secure Timers (stimer0~stimer11) and 2 Timers (pmutimer0~pmutimer1), we mainly use Timers (timer0-timer11) clock frequency is 24MHZ, working mode There are free-running
and user-defined count
modes.
The framework¶
Working mode¶
user-defined count
: Timer first loads the initial value into the TIMERn_LOAD_COUNT3 and TIMER_LOADn_COUNT2 registers. When the time accumulated value is in the registers TIMERn_LOAD_COUNT1 and TIMERn_LOAD_COUNT0, it will not be automatically loaded into the count register. The user needs to turn off the counter and then reset the counter to continue working.free-running
: Timer first loads the initial value into the TIMER_LOAD_COUNT3 and TIMER_LOAD_COUNT2 registers. When the time accumulated value is in the registers TIMERn_LOAD_COUNT1 and TIMERn_LOAD_COUNT0, the Timer will always load the count register automatically.
Software configuration¶
Define the relevant configuration of Timer in the dts file
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";
};
The registers of Timer0, interrupt number and clock defined therein.
The interrupt numbers corresponding to other Timers can be seen in the following pictures:
Corresponding driver file
Kernel/drivers/clocksource/rockchip_timer.c
Corresponding registers and usage¶
The register is as follows:
Use the
io
command to view the corresponding register:
root@host???:/ # io -4 0xff85001c //View the status of the current control register
ff85001c: 00000007
root@host???:/ # io -4 0xff850000 //Check the current value of the register
ff850000: 0001639f
Control corresponding register:
root@host???:/ # io -4 -w 0xff85001c 0x06 //Turn off time counting