RE: Accessing flash directly from User Space
From: Jonathan Haws <hidden>
Date: 2009-10-28 14:39:03
On Tue, Oct 27, 2009 at 04:24:53PM -0600, Jonathan Haws wrote:quoted
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How can I get that pointer? Unfortunately I cannot simplyusequoted
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address of the flash. Is there some magical function callthatquoted
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gives me access to that portion of the memory space? $ man 2 mmap You want MAP_SHARED and O_SYNC.To use that I need to have a file descriptor to a device, do Inot? However, I do not have a base flash driver to give me that file descriptor. Am I missing something with that call?quoted
/dev/memOkay, I now have access to the flash memory, however when I writeto it the writes do not take. I have tried calling msync() on the mapping to no avail. I have opened the fd with O_SYNC, but cannot get things to work right.quoted
Here are the calls: int fd =3D open("/dev/mem", O_SYNC | O_RDWR); uint16_t * flash =3D (uint16_t *)mmap(NULL, NOR_FLASH_SIZE, (PROT_READ | PROT_WRITE), MAP_PRIVATE, fd, NOR_FLASH_BASE_ADRS);=20 What board and CPU are you using? Is your flash really at 0xFC800000, or is that the virtual address that VxWorks puts it at?
I am using a custom board based on the AMCC Kilauea development board. It = uses a 405EX CPU. Yes, the flash is really at 0xFC000000.