NCR 7452/3 POS - Retail CMOS NVRAM Driver

[Gabriel Gomiz]

I say Hi to the greatests hackers!

I'm trying to build a kernel module driver to be able to access the CMOS 
NVRAM that the NCR 7452/3 POS (Point of Sale) has built-in on the 
motherboard. All the information that I could get from the manufacturers 
is that the memory works at I/O address 0x100. But later I found out 
that you can configure the I/O address using switches on the motherboard 
to one of the following ranges of addresses:
0x100-0x10F DEFAULT
0x120-0x12F
0x140-0x14F
0x160-0x16F

The memory chips that NCR uses are:
1) NEC D43256BGU - NCR POS Model 7452-1011
    The chip is 256KB, but NCR says they use only 128KB
2) NEC D431000AGW - NCR POS Model 7453-1011
    The chip is 1MB, but NCR says they use only 128KB

I've made a simple kernel module (based on drivers/char/nvram.c) to see 
if I can _test_ the memory (to see if it is there and read/write some 
bytes from 0x100 I/O Port) and I'm getting some confusing results.
In the end the module does the following:

#ifndef NVRAM_PORT
#define NVRAM_PORT(x)	(0x100 + (x))
#endif

#define NVRAM_READ(addr) ({ \
outb_p((addr),NVRAM_PORT(0)); \
inb_p(NVRAM_PORT(1)); \
})

#define NVRAM_WRITE(val, addr) ({ \
outb_p((addr),NVRAM_PORT(0)); \
outb_p((val),NVRAM_PORT(1)); \
})

The questions are:

* Has anyone worked with this kind of NVRAM before?
* Do you know how can the memory be programmed? Maybe you can enlight me 
with something... :)

I have some more details of the module and the tests I've been doing to 
send if someone is interested.

OBS: If this message is considered highly off-topic, please can you 
point me in the right direction to ask this questions? (Maybe linux-mtd???)

Many thanks in advance

-- 
    .^.    Gabriel Gomiz - Red Hat Certified Engineer (RHCE)
    /V\
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