Mapping physical address to virtual page address Issue.

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1

Hi

I am using beagle bone black and writing i2c driver just for learning.
I used am335x TRM and i2c1 at address 0x4802a000 as mentioned in TRM.

I did the following :

void * addr = ioremap(phy_addr, length);
unsigned x = readl(addr);

Where phy_addr is the physical address (0x4802a000) mentioned in TRM.
And length is the end address - start address (0x4802afff - 0x4802a000)

Now on ‘read’ it crashes and gives me the following error when checked in dmesg :
Unhandled fault: external abort on non-linefetch.

Need help on this.

Thanks:)

2

Check out "http://free-electrons.com/pub/mirror/devmem2.c"

The OS can place memory blocks anywhere and keeps track of the mapping.
You need to use mmap to translate an address from the TRM to /dev/mem.

Hope this helps.
Chad