Linux/EVMK2GX: Remapping L3 to an uncached region

Elron A Yellin

Part Number: EVMK2GX

Tool/software: Linux

I have a PCIe device writing into L3. I want to remap L3 to an uncached address range. Which ranges are valid to use and what do I need to do to keep linux from trampling my chosen range.

I've tried using 0xC0000000 (and other base addresses), and adding a carveout in the resource table, but the mapped addresses don't read back correctly.

	uintptr_t L3 = 0x0C000000;
	uintptr_t mapped = 0xC0000000;
	CSL_XMC_XMPAXH high = { mapped >> CSL_XMC_XMPAXH_BADDR_SHIFT, 0x1B };
	CSL_XMC_XMPAXL low = {  L3 >> CSL_XMC_XMPAXL_RADDR_SHIFT, 1, 1, 0, 1, 1, 0 };
	CSL_XMC_setXMPAXH(2, &high);
	CSL_XMC_setXMPAXL(2, &low);
	CACHE_disableCaching(mapped >> 24);

Thanks

over 7 years ago

0 Yordan Kovachev over 7 years ago

TI__Guru**** 161600 points

Hi Elron,

Are you using TI Linux or TI RTOS on your EVMK2GX? Which version?

Best Regards,
Yordan

0 Elron A Yellin over 7 years ago in reply to Yordan Kovachev

Expert 1040 points

TI-RTOS on the C66 and linux on the ARM.

bios_6_52_00_12

ti-processor-sdk-linux-k2g-evm-04.03.00.05

ipc_3_47_01_00

0 Elron A Yellin over 7 years ago

Expert 1040 points

I made three mistakes:
The mapping is from a logical address to a 36-bit address, so raddr should have been (L3 >> 4) >> CSL_XMC_XMPAXL_RADDR_SHIFT
I mapped more than I needed, and it happens that if you map more than 64MB starting at 0x0C000000 the translation doesn't work even for addresses that are in within the MSMC SRAM.
I need not have worried about linux and my arbitrarily chosen baddr, since it's a logical address.

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Linux/EVMK2GX: Remapping L3 to an uncached region