Linux/AM3359: Timer driver

Mobin P K

Expert 1035 points

Part Number: AM3359

Tool/software: Linux

Sir,

Kindly share the timer driver for AM3359 processor which uses Linux OS.

regards

Mobin P K

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Timer drivers are included in the Linux SDK: www.ti.com/.../PROCESSOR-SDK-AM335X

0 Mobin P K over 6 years ago in reply to Biser Gatchev-XID

Expert 1035 points

Hello,

I have found that in /proc/devices timer drivers are not availble for accessing processor timer. How do I include the timer driver with the help of Yocto project.

thanks
Mobin P K

0 Pavel Botev over 6 years ago in reply to Mobin P K

TI__Guru**** 170625 points

Mobin,

Which timer exactly you refer to? Let take for example timer4 (base addr 0x48044000), the kernel drivers are:

linux-4.14.40/arch/arm/mach-omap2/timer.c
linux-4.14.40/drivers/clocksource/timer-ti-dm.c
linux-4.14.40/drivers/pwm/pwm-omap-dmtimer.c

Regards,
Pavel

0 Mobin P K over 6 years ago in reply to Pavel Botev

Expert 1035 points

Sir,

I have found the timer device under /dev/snd folder as timer. How do I access it from the user level. kindly share the driver APIS.

thanks
Mobin

0 Pavel Botev over 6 years ago in reply to Mobin P K

TI__Guru**** 170625 points

Mobin,

/dev/snd/timer is used only for ALSA audio purpose. Refer to the below pointers for more info and examples:

www.alsa-project.org/.../timer.html
gist.github.com/.../002deb09f3323527a4bf225749fb965d

Regards,
Pavel

0 Pavel Botev over 6 years ago in reply to Pavel Botev

TI__Guru**** 170625 points

Check also below e2e threads:

e2e.ti.com/.../655571
e2e.ti.com/.../660867

Regards,
Pavel

0 Mobin P K over 6 years ago in reply to Pavel Botev

Expert 1035 points

Sir,

I have found the dmtimer.c with in the path linux/arch/arm/plat-omap and is compiled default with OS.

I am developing the application in Eclipse IDE, Kindly share the User APIs for accessing the dmtimer for AM3359 Processor.

thanks

Mobin P K

0 Pavel Botev over 6 years ago in reply to Mobin P K

TI__Guru**** 170625 points

Mobin,

We have kernel API for sure, but userspace API might be limited. See for example how EMAC modules is using time stamp events from user space timer:

processors.wiki.ti.com/.../Linux_Core_CPSW_User's_Guide

Check also below links:

e2e.ti.com/.../133674

stackoverflow.com/.../how-to-implement-highly-accurate-timers-in-linux-userspace
man7.org/.../timer_create.2.html

Regards,
Pavel

0 Mobin P K over 6 years ago in reply to Pavel Botev

Expert 1035 points

Sir,

thanks for your reply

Is it possible to call DMTimerEnable() function from user space for accessing DMTimer0 to DMTimer6 ??

thanks

0 Pavel Botev over 6 years ago in reply to Mobin P K

TI__Guru**** 170625 points

Mobin,

What is this DMTimerEnable() function? I am not able to find such function, please provide more details.

Regards,
Pavel

0 Mobin P K over 6 years ago in reply to Pavel Botev

Expert 1035 points

Sir

Find the DMTimerEnable() function definition taken from dmtimer.c
/*******************************************************************************
* API FUNCTION DEFINITIONS
*******************************************************************************/

/**
* \brief This API will start the timer.
*
* \param baseAdd Base Address of the DMTimer Module Register.
*
* \return None.
*
* \note The timer must be configured before it is started/enabled.
*
**/
void DMTimerEnable(unsigned int baseAdd)
{
/* Start the timer */
HWREG(baseAdd + DMTIMER_TCLR) |= DMTIMER_TCLR_ST;
}

thanks

Mobin P K

0 Pavel Botev over 6 years ago in reply to Mobin P K

TI__Guru**** 170625 points

Mobin,

Do you use AM335x TI PSDK? If yes, which version? I can not find DMTimerEnable() function in the latest PSDK v5.00

As this seems to be kernel level function, then my answer is: no, you can not call it directly from user space. You should create your own user space application, and map timer registers with mmap() function, thus you will be able to access timer registers (i.e. TCLR register).

Regards,
Pavel

0 Pavel Botev over 6 years ago in reply to Pavel Botev

TI__Guru**** 170625 points

If you have no more questions related to the subject, please close/verify/resolve this thread.

Regards,
Pavel

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Linux/AM3359: Timer driver