Re: Read CCNT on PXA255

[Gilles Chanteperdrix <gilles.chanteperdrix@xxxxxxxxxxx>]

Junaid Jamil wrote:
> Hi, I want to read CCNT cycle clock register of PXA255. But I am
> getting problem accessing these registers. In a sample C program when
> I try to read CCNT and PMNC via assembly instructions (given below) as
> mentioned in manual of PXA, it reports illegle instruction. These
> instuction are: for PMNC: __asm__volatile__("mrc p14, 0, %0, c0, c0,
> 0" : "=r" (val)); for CCNT __asm__volatile__("mrc p14, 0, %0, c1, c0,
> 0" : "=r" (val)); I am using arm-linux-gcc 3.3.2 to successfully
> compile this program. The run time error when this program is run are
> given as: for PMNC: e5933000 e5933000 e3530000 1a000002 (ee103e10)
> Illegle instruction; for CCNT: e5933000 e5933000 e3530000 1a000002
> (ee193f1e) Illegale instruction; Can any one please guide me how to
> fix this. Junaid

If you want to get some cycles count, you may map the OSCR counter in
user-space. A simple way to do this, is to map it with mmap, using
/dev/mem and the counter hardware address. The PXA OSCR hardware address
is 0x40A00010.

-- 


					    Gilles.

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