This question may be simple for you, but it doesn't let me sleeping.
From: John Zhou <hidden>
Date: 2002-02-13 06:32:44
Dear all, This question may be simple for you, but it doesn't let me sleeping. I have linux2.4.1 from Lineo runing on ppc8250, IMMR = 0xF0000000, in my driver function, I can directly access 0xF00xxxxx( internal memory area on PPC's chip), why? I think , in device driver, we also use logical memory, when accessing physical address, it should first map this address to be accessed by hardware. Is it right? Another, I write a character driver to operate I2C device. When passing a logical address pointer to BD's address pointer that allocated by function kmalloc(). I can't correctly operate I2C device, But when I used free memory located in IMM ( 0xF00037C0 ~ 0xF00037F0 ) and directly pass this address to BD's buffer pointer, I can correctly operate I2C device. I also try to use function __pa() and virt_to_phys() to map logical address to physical address, The driver still can't work OK. Any comments and suggestions are appreciated! John Zhou ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/