Re: 1 euro Olimex RISC-V mini-PC: this needs Forth ;)

Waldek Hebisch <antispam@fricas.org> wrote:

albert@spenarnc.xs4all.nl wrote:

In article <vf5a40$2fkdi$1@paganini.bofh.team>,
Waldek Hebisch <antispam@fricas.org> wrote:
<SNIP>

>
RISCV ciforth beta 2023Mar30
MMAP-IO
OK
HEX
OK
VMA-IO @ .
B2000000  OK
DEV-MEM @ .
3  OK
>

Encouraging.
 

Datasheet says that device address space starts at 0x01000000
and ends at 0x7FFFFFFF (above is DRAM).  There is a command
line utility to do I/O.  Sending 0x01000000 to 0x03022000 turns on
blue LED, sending 0x0 truns it off.  AFAICS in lina corresponding
address is B2022000.  More generally, there are four GPIO devices
(ports).  Port 0 is at 0x03020000, port 1 at 0x03021000, port 2 at
0x03022000, port 3 at 0x03023000.  Device access should be done in
32-bit units.

 
This suggest that you can do the same from lina using virtual
addresses B302x000 . That is vma-io + 0x0100,0000 (device start) + 2x000.
You probably have to initialize the ports to output in some way
for this to work.

 
I tried first things like above and got segfaults.  AFAICS lina B2000000
corresponds to 0x3000000 in device space, so 0x03022000 corresponds to
B2022000.  It seems that lina did not map block between 0x1000000
and 0x3000000, in this block that are 'ap_mailbox' and 'ap_system_ctrl',
it is probably not wise to mess with them from user space.
 

All io must be accessed with 32 bit. lina provides L! L@ for
this. (My conventions is B-W-L-Q ).

 
1000000 B2022000 L!
 OK
0 B2022000 L!
 OK
 
blinks the LED.  I tried and 64-bit access works too, but it reads
or writes also the second register, so L! and L@ are simpler to use.

Milkv Duos have 5 GPIO ports, formally 32-bit but many lines are
not connected to outputs.  One port in RTC block and has
base address 0x05021000, the other ports are at 0x03020000 + n*0x1000
where n is port number.  Output register is at offset 0, at offset
4 is direction register (setting bit to 1 means that line is an
output).  At offset 0x50 is input register.  Other registers
deal with interrupts.

ATM I have the following:

HEX
: LBIS DUP L@ ROT OR SWAP L! ;
: LBIC DUP L@ ROT INVERT AND SWAP L! ;
: gpio-base DUP 4 = IF DROP 2001000 ELSE 1000 * THEN VMA-IO @ + 20000 + ;
: bit-data 20 /MOD SWAP 1 SWAP LSHIFT SWAP gpio-base ;
: gpio-on bit-data LBIS ;
: gpio-off bit-data LBIC ;

which outputs bits to data register.  To get actual output one
need to set direction register and associate PIN with GPIO function.
There is something more, I tried to hijack Ethernet pins bit I
got no output.  Theoretically pins were associated with GPIO
function and lines were set to output, writes changed data
register, but voltage on the pin did not change.  OTOH, by
changing UART0 TX pin to GPIO is got output, so there is
something special about Ethernet.

BTW: Chip datasheet talks about ports and pin numbers within
ports, Milkv Duo picture uses pin numbers but there is mixup
with ports.  There is command line outility to deal with pins,
it uses different numbering similar to numbering on the board
but not the same.  Linux uses still different ping numbering.
Above I use pin number withing port + 32*port number where
ports are numbered from 0.

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                              Waldek Hebisch