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Enhanced Ethernet drivers.

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Made Ethernet drivers easier to consume by assembly programs.
* Replaced function pointers with JMP instructions.
* Provide return values additionally via Carry flag.

Reset Ethernet chips on initialization.
Both for the CS8900A and the W5100 the data sheets just say that
the RESET bit is automatically cleared after the RESET. This may
be interpreted in two ways:
1) There's no need to be afraid of reading the RESET bit as 1 and
unintentionally trigger a RESET by writing it back after ORing in
some other bit.
2) The RESET process isn't complete before the RESET bit hasn't
become 0 again.
It's impossible for me to empirically falsify the latter option
as the drivers are supposed to work on faster machines than the
ones I have access to. And if the RESET process includes things
like oscillators then the time to complete the RESET could differ
even between multiple exemplars of the same chip. Therefore I
opted to presume the latter option.
However that means a non-exsistent chip may cause an infinite
loop while waiting for the RESET bit to be cleared so I finally
added code to detect the presence of the Ethernet chips. There's
a risk of a chip being locked up in a way that makes the detection
fail - and therefore the RESET not being performed. This catch-22
needs to be solved by the user doing a hard RESET.
This commit is contained in:
Oliver Schmidt 2014-06-12 22:56:35 +02:00
parent a0961fc3c4
commit a5d7a06027
4 changed files with 177 additions and 109 deletions
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11
cpu/6502/net/ethernet.c
View file

@ -47,9 +47,13 @@ struct {
struct uip_eth_addr ethernet_address;
uint8_t *buffer;
uint16_t buffer_size;
void __fastcall__ (* init)(uint16_t reg);
char jmp_init;
char __fastcall__ (* init)(uint16_t reg);
char jmp_poll;
uint16_t (* poll)(void);
char jmp_send;
void __fastcall__ (* send)(uint16_t len);
char jmp_exit;
void (* exit)(void);
} *module;
@ -97,7 +101,10 @@ ethernet_init(struct ethernet_config *config)
module->buffer = uip_buf;
module->buffer_size = UIP_BUFSIZE;
module->init(config->addr);
if(module->init(config->addr)) {
log_message(config->name, ": No hardware");
error_exit();
}
uip_setethaddr(module->ethernet_address);
}