Linux/AM5718: Timer clock configuration

S.K. Huang

Intellectual 270 points

Part Number: AM5718

Tool/software: Linux

Hi,

SDK version is 4.01.00.06 and the SOC is AM5718.

Our system clock choice the 20MHz crystal..

I want to use 20MHz for the timer.

I try timer2~timer16. All clock are 32768Hz. (timer1 already used in the kernel init.)

For the Device Tree,

timer2: timer@48032000 {
compatible = "ti,omap5430-timer";
reg = <0x48032000 0x80>;
interrupts = <GIC_SPI 33 IRQ_TYPE_LEVEL_HIGH>;
ti,hwmods = "timer2";
ti,timer-alwon;
};

timer2_gfclk_mux: timer2_gfclk_mux@1738 {
#clock-cells = <0>;
compatible = "ti,mux-clock";
clocks = <&timer_sys_clk_div>, <&sys_32k_ck>, <&sys_clkin2>, <&ref_clkin0_ck>, <&ref_clkin1_ck>, <&ref_clkin2_ck>, <&ref_clkin3_ck>, <&abe_giclk_div>, <&video1_div_clk>, <&video2_div_clk>, <&hdmi_div_clk>;
ti,bit-shift = <24>;
reg = <0x1738>;
};

Can you give me a example How to use 20MHz(OMAP_TIMER_SRC_SYS_CLK)?

Thanks.

S.K.

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

The software team have been notified. They will respond here.

0 Pavel Botev over 8 years ago

TI__Guru**** 170625 points

Hi Huang,

You can use the AM57x clock tree tool to get the exact clock configuration you need.

www.ti.com/.../clocktreetool

Regards,
Pavel

0 S.K. Huang over 8 years ago in reply to Pavel Botev

Intellectual 270 points

Hi Pravel,

I will try that tool again. I ever did it. But I still don't understand the flow of device tree.

Do you mean that I can directly write the registers without the device tree?

For example, I check them from the register table and replace the register value for the timer clock.

DeviceName AM571x_SR2.0_SR1.0
[0x4a002134] 0x000000c0
[0x4a002148] 0x00000000
[0x4a002150] 0x00000000
[0x4a00215c] 0x00000000
[0x4a002194] 0x00000000
[0x4a002198] 0x00000000
[0x4a00219c] 0x00000000
[0x4a0021a0] 0x00000000
[0x4a0021a4] 0x00000000

......

Thanks.

S.K.

0 Pavel Botev over 8 years ago in reply to S.K. Huang

TI__Guru**** 170625 points

Huang,

To get OSC1 (20MHz) clock source for timer2, you need to have 0x0 value in the below bit-field:

CM_L4PER_TIMER2_CLKCTRL[27:24] CLKSEL = 0x0

Can you check what value you have there in user space, with devmem2/omapconf tool?

0 Pavel Botev over 8 years ago in reply to Pavel Botev

TI__Guru**** 170625 points

Check also what parent clock is set and what frequency you have for timer2_gfclk_mux clock in the below function:

linux-kernel/drivers/clk/ti/clk-7xx.c
dra7xx_dt_clk_init()

Regards,
Pavel

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Linux/AM5718: Timer clock configuration