ref: 567b1b912a91bf56bebacc67b6a467986d5bed6c
dir: /sys/src/9/teg2/uarti8250.c/
/*
* 8250-like UART
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
enum { /* registers */
Rbr = 0, /* Receiver Buffer (RO) */
Thr = 0, /* Transmitter Holding (WO) */
Ier = 1, /* Interrupt Enable */
Iir = 2, /* Interrupt Identification (RO) */
Fcr = 2, /* FIFO Control (WO) */
Lcr = 3, /* Line Control */
Mcr = 4, /* Modem Control */
Lsr = 5, /* Line Status */
Msr = 6, /* Modem Status */
Scr = 7, /* Scratch Pad */
Mdr = 8, /* Mode Def'n (omap rw) */
// Usr = 31, /* Uart Status Register; missing in omap? */
Dll = 0, /* Divisor Latch LSB */
Dlm = 1, /* Divisor Latch MSB */
};
enum { /* Usr */
Busy = 0x01,
};
enum { /* Ier */
Erda = 0x01, /* Enable Received Data Available */
Ethre = 0x02, /* Enable Thr Empty */
Erls = 0x04, /* Enable Receiver Line Status */
Ems = 0x08, /* Enable Modem Status */
};
enum { /* Iir */
Ims = 0x00, /* Ms interrupt */
Ip = 0x01, /* Interrupt Pending (not) */
Ithre = 0x02, /* Thr Empty */
Irda = 0x04, /* Received Data Available */
Irls = 0x06, /* Receiver Line Status */
Ictoi = 0x0C, /* Character Time-out Indication */
IirMASK = 0x3F,
Ifena = 0xC0, /* FIFOs enabled */
};
enum { /* Fcr */
FIFOena = 0x01, /* FIFO enable */
FIFOrclr = 0x02, /* clear Rx FIFO */
FIFOtclr = 0x04, /* clear Tx FIFO */
// FIFOdma = 0x08,
FIFO1 = 0x00, /* Rx FIFO trigger level 1 byte */
FIFO4 = 0x40, /* 4 bytes */
FIFO8 = 0x80, /* 8 bytes */
FIFO14 = 0xC0, /* 14 bytes */
};
enum { /* Lcr */
Wls5 = 0x00, /* Word Length Select 5 bits/byte */
Wls6 = 0x01, /* 6 bits/byte */
Wls7 = 0x02, /* 7 bits/byte */
Wls8 = 0x03, /* 8 bits/byte */
WlsMASK = 0x03,
Stb = 0x04, /* 2 stop bits */
Pen = 0x08, /* Parity Enable */
Eps = 0x10, /* Even Parity Select */
Stp = 0x20, /* Stick Parity */
Brk = 0x40, /* Break */
Dlab = 0x80, /* Divisor Latch Access Bit */
};
enum { /* Mcr */
Dtr = 0x01, /* Data Terminal Ready */
Rts = 0x02, /* Ready To Send */
Out1 = 0x04, /* no longer in use */
// Ie = 0x08, /* IRQ Enable (cd_sts_ch on omap) */
Dm = 0x10, /* Diagnostic Mode loopback */
};
enum { /* Lsr */
Dr = 0x01, /* Data Ready */
Oe = 0x02, /* Overrun Error */
Pe = 0x04, /* Parity Error */
Fe = 0x08, /* Framing Error */
Bi = 0x10, /* Break Interrupt */
Thre = 0x20, /* Thr Empty */
Temt = 0x40, /* Transmitter Empty */
FIFOerr = 0x80, /* error in receiver FIFO */
};
enum { /* Msr */
Dcts = 0x01, /* Delta Cts */
Ddsr = 0x02, /* Delta Dsr */
Teri = 0x04, /* Trailing Edge of Ri */
Ddcd = 0x08, /* Delta Dcd */
Cts = 0x10, /* Clear To Send */
Dsr = 0x20, /* Data Set Ready */
Ri = 0x40, /* Ring Indicator */
Dcd = 0x80, /* Carrier Detect */
};
enum { /* Mdr */
Modemask = 7,
Modeuart = 0,
};
typedef struct Ctlr {
u32int* io;
int irq;
int tbdf;
int iena;
int poll;
uchar sticky[Scr+1];
Lock;
int hasfifo;
int checkfifo;
int fena;
} Ctlr;
extern PhysUart i8250physuart;
static Ctlr i8250ctlr[] = {
{ .io = (u32int*)PHYSCONS,
.irq = Uartirq,
.tbdf = -1,
.poll = 0, },
};
static Uart i8250uart[] = {
{ .regs = &i8250ctlr[0], /* not [2] */
.name = "COM3",
.freq = 3686000, /* Not used, we use the global i8250freq */
.phys = &i8250physuart,
.console= 1,
.next = nil, },
};
#define csr8r(c, r) ((c)->io[r])
#define csr8w(c, r, v) ((c)->io[r] = (c)->sticky[r] | (v), coherence())
#define csr8o(c, r, v) ((c)->io[r] = (v), coherence())
static long
i8250status(Uart* uart, void* buf, long n, long offset)
{
char *p;
Ctlr *ctlr;
uchar ier, lcr, mcr, msr;
ctlr = uart->regs;
p = malloc(READSTR);
mcr = ctlr->sticky[Mcr];
msr = csr8r(ctlr, Msr);
ier = ctlr->sticky[Ier];
lcr = ctlr->sticky[Lcr];
snprint(p, READSTR,
"b%d c%d d%d e%d l%d m%d p%c r%d s%d i%d\n"
"dev(%d) type(%d) framing(%d) overruns(%d) "
"berr(%d) serr(%d)%s%s%s%s\n",
uart->baud,
uart->hup_dcd,
(msr & Dsr) != 0,
uart->hup_dsr,
(lcr & WlsMASK) + 5,
(ier & Ems) != 0,
(lcr & Pen) ? ((lcr & Eps) ? 'e': 'o'): 'n',
(mcr & Rts) != 0,
(lcr & Stb) ? 2: 1,
ctlr->fena,
uart->dev,
uart->type,
uart->ferr,
uart->oerr,
uart->berr,
uart->serr,
(msr & Cts) ? " cts": "",
(msr & Dsr) ? " dsr": "",
(msr & Dcd) ? " dcd": "",
(msr & Ri) ? " ring": ""
);
n = readstr(offset, buf, n, p);
free(p);
return n;
}
static void
i8250fifo(Uart* uart, int level)
{
Ctlr *ctlr;
ctlr = uart->regs;
if(ctlr->hasfifo == 0)
return;
/*
* Changing the FIFOena bit in Fcr flushes data
* from both receive and transmit FIFOs; there's
* no easy way to guarantee not losing data on
* the receive side, but it's possible to wait until
* the transmitter is really empty.
*/
ilock(ctlr);
while(!(csr8r(ctlr, Lsr) & Temt))
;
/*
* Set the trigger level, default is the max.
* value.
* Some UARTs require FIFOena to be set before
* other bits can take effect, so set it twice.
*/
ctlr->fena = level;
switch(level){
case 0:
break;
case 1:
level = FIFO1|FIFOena;
break;
case 4:
level = FIFO4|FIFOena;
break;
case 8:
level = FIFO8|FIFOena;
break;
default:
level = FIFO14|FIFOena;
break;
}
csr8w(ctlr, Fcr, level);
csr8w(ctlr, Fcr, level);
iunlock(ctlr);
}
static void
i8250dtr(Uart* uart, int on)
{
Ctlr *ctlr;
/*
* Toggle DTR.
*/
ctlr = uart->regs;
if(on)
ctlr->sticky[Mcr] |= Dtr;
else
ctlr->sticky[Mcr] &= ~Dtr;
csr8w(ctlr, Mcr, 0);
}
static void
i8250rts(Uart* uart, int on)
{
Ctlr *ctlr;
/*
* Toggle RTS.
*/
ctlr = uart->regs;
if(on)
ctlr->sticky[Mcr] |= Rts;
else
ctlr->sticky[Mcr] &= ~Rts;
csr8w(ctlr, Mcr, 0);
}
static void
i8250modemctl(Uart* uart, int on)
{
Ctlr *ctlr;
ctlr = uart->regs;
ilock(&uart->tlock);
if(on){
ctlr->sticky[Ier] |= Ems;
csr8w(ctlr, Ier, 0);
uart->modem = 1;
uart->cts = csr8r(ctlr, Msr) & Cts;
}
else{
ctlr->sticky[Ier] &= ~Ems;
csr8w(ctlr, Ier, 0);
uart->modem = 0;
uart->cts = 1;
}
iunlock(&uart->tlock);
/* modem needs fifo */
(*uart->phys->fifo)(uart, on);
}
static int
i8250parity(Uart* uart, int parity)
{
int lcr;
Ctlr *ctlr;
ctlr = uart->regs;
lcr = ctlr->sticky[Lcr] & ~(Eps|Pen);
switch(parity){
case 'e':
lcr |= Eps|Pen;
break;
case 'o':
lcr |= Pen;
break;
case 'n':
break;
default:
return -1;
}
ctlr->sticky[Lcr] = lcr;
csr8w(ctlr, Lcr, 0);
uart->parity = parity;
return 0;
}
static int
i8250stop(Uart* uart, int stop)
{
int lcr;
Ctlr *ctlr;
ctlr = uart->regs;
lcr = ctlr->sticky[Lcr] & ~Stb;
switch(stop){
case 1:
break;
case 2:
lcr |= Stb;
break;
default:
return -1;
}
ctlr->sticky[Lcr] = lcr;
csr8w(ctlr, Lcr, 0);
uart->stop = stop;
return 0;
}
static int
i8250bits(Uart* uart, int bits)
{
int lcr;
Ctlr *ctlr;
ctlr = uart->regs;
lcr = ctlr->sticky[Lcr] & ~WlsMASK;
switch(bits){
case 5:
lcr |= Wls5;
break;
case 6:
lcr |= Wls6;
break;
case 7:
lcr |= Wls7;
break;
case 8:
lcr |= Wls8;
break;
default:
return -1;
}
ctlr->sticky[Lcr] = lcr;
csr8w(ctlr, Lcr, 0);
uart->bits = bits;
return 0;
}
static int
i8250baud(Uart* uart, int baud)
{
#ifdef notdef /* don't change the speed */
ulong bgc;
Ctlr *ctlr;
extern int i8250freq; /* In the config file */
/*
* Set the Baud rate by calculating and setting the Baud rate
* Generator Constant. This will work with fairly non-standard
* Baud rates.
*/
if(i8250freq == 0 || baud <= 0)
return -1;
bgc = (i8250freq+8*baud-1)/(16*baud);
ctlr = uart->regs;
while(csr8r(ctlr, Usr) & Busy)
delay(1);
csr8w(ctlr, Lcr, Dlab); /* begin kludge */
csr8o(ctlr, Dlm, bgc>>8);
csr8o(ctlr, Dll, bgc);
csr8w(ctlr, Lcr, 0);
#endif
uart->baud = baud;
return 0;
}
static void
i8250break(Uart* uart, int ms)
{
Ctlr *ctlr;
if (up == nil)
panic("i8250break: nil up");
/*
* Send a break.
*/
if(ms <= 0)
ms = 200;
ctlr = uart->regs;
csr8w(ctlr, Lcr, Brk);
tsleep(&up->sleep, return0, 0, ms);
csr8w(ctlr, Lcr, 0);
}
static void
i8250kick(Uart* uart)
{
int i;
Ctlr *ctlr;
/* nothing more to send? then disable xmit intr */
ctlr = uart->regs;
if (uart->op >= uart->oe && qlen(uart->oq) == 0 &&
csr8r(ctlr, Lsr) & Temt) {
ctlr->sticky[Ier] &= ~Ethre;
csr8w(ctlr, Ier, 0);
return;
}
/*
* 128 here is an arbitrary limit to make sure
* we don't stay in this loop too long. If the
* chip's output queue is longer than 128, too
* bad -- presotto
*/
for(i = 0; i < 128; i++){
if(!(csr8r(ctlr, Lsr) & Thre))
break;
if(uart->op >= uart->oe && uartstageoutput(uart) == 0)
break;
csr8o(ctlr, Thr, *uart->op++); /* start tx */
ctlr->sticky[Ier] |= Ethre;
csr8w(ctlr, Ier, 0); /* intr when done */
}
}
static void
i8250interrupt(Ureg*, void* arg)
{
Ctlr *ctlr;
Uart *uart;
int iir, lsr, old, r;
uart = arg;
ctlr = uart->regs;
for(iir = csr8r(ctlr, Iir); !(iir & Ip); iir = csr8r(ctlr, Iir)){
switch(iir & IirMASK){
case Ims: /* Ms interrupt */
r = csr8r(ctlr, Msr);
if(r & Dcts){
ilock(&uart->tlock);
old = uart->cts;
uart->cts = r & Cts;
if(old == 0 && uart->cts)
uart->ctsbackoff = 2;
iunlock(&uart->tlock);
}
if(r & Ddsr){
old = r & Dsr;
if(uart->hup_dsr && uart->dsr && !old)
uart->dohup = 1;
uart->dsr = old;
}
if(r & Ddcd){
old = r & Dcd;
if(uart->hup_dcd && uart->dcd && !old)
uart->dohup = 1;
uart->dcd = old;
}
break;
case Ithre: /* Thr Empty */
uartkick(uart);
break;
case Irda: /* Received Data Available */
case Irls: /* Receiver Line Status */
case Ictoi: /* Character Time-out Indication */
/*
* Consume any received data.
* If the received byte came in with a break,
* parity or framing error, throw it away;
* overrun is an indication that something has
* already been tossed.
*/
while((lsr = csr8r(ctlr, Lsr)) & Dr){
if(lsr & (FIFOerr|Oe))
uart->oerr++;
if(lsr & Pe)
uart->perr++;
if(lsr & Fe)
uart->ferr++;
r = csr8r(ctlr, Rbr);
if(!(lsr & (Bi|Fe|Pe)))
uartrecv(uart, r);
}
break;
default:
iprint("weird uart interrupt type %#2.2uX\n", iir);
break;
}
}
}
static void
i8250disable(Uart* uart)
{
Ctlr *ctlr;
/*
* Turn off DTR and RTS, disable interrupts and fifos.
*/
(*uart->phys->dtr)(uart, 0);
(*uart->phys->rts)(uart, 0);
(*uart->phys->fifo)(uart, 0);
ctlr = uart->regs;
ctlr->sticky[Ier] = 0;
csr8w(ctlr, Ier, 0);
if(ctlr->iena != 0){
if(irqdisable(ctlr->irq, i8250interrupt, uart, uart->name) == 0)
ctlr->iena = 0;
}
}
static void
i8250enable(Uart* uart, int ie)
{
int mode;
Ctlr *ctlr;
ctlr = uart->regs;
/* omap only: set uart/irda/cir mode to uart */
mode = csr8r(ctlr, Mdr);
csr8o(ctlr, Mdr, (mode & ~Modemask) | Modeuart);
ctlr->sticky[Lcr] = Wls8; /* no parity */
csr8w(ctlr, Lcr, 0);
/*
* Check if there is a FIFO.
* Changing the FIFOena bit in Fcr flushes data
* from both receive and transmit FIFOs; there's
* no easy way to guarantee not losing data on
* the receive side, but it's possible to wait until
* the transmitter is really empty.
* Also, reading the Iir outwith i8250interrupt()
* can be dangerous, but this should only happen
* once, before interrupts are enabled.
*/
ilock(ctlr);
if(!ctlr->checkfifo){
/*
* Wait until the transmitter is really empty.
*/
while(!(csr8r(ctlr, Lsr) & Temt))
;
csr8w(ctlr, Fcr, FIFOena);
if(csr8r(ctlr, Iir) & Ifena)
ctlr->hasfifo = 1;
csr8w(ctlr, Fcr, 0);
ctlr->checkfifo = 1;
}
iunlock(ctlr);
/*
* Enable interrupts and turn on DTR and RTS.
* Be careful if this is called to set up a polled serial line
* early on not to try to enable interrupts as interrupt-
* -enabling mechanisms might not be set up yet.
*/
if(ie){
if(ctlr->iena == 0 && !ctlr->poll){
irqenable(ctlr->irq, i8250interrupt, uart, uart->name);
ctlr->iena = 1;
}
ctlr->sticky[Ier] = Erda;
// ctlr->sticky[Mcr] |= Ie; /* not on omap */
ctlr->sticky[Mcr] = 0;
}
else{
ctlr->sticky[Ier] = 0;
ctlr->sticky[Mcr] = 0;
}
csr8w(ctlr, Ier, 0);
csr8w(ctlr, Mcr, 0);
(*uart->phys->dtr)(uart, 1);
(*uart->phys->rts)(uart, 1);
/*
* During startup, the i8259 interrupt controller is reset.
* This may result in a lost interrupt from the i8250 uart.
* The i8250 thinks the interrupt is still outstanding and does not
* generate any further interrupts. The workaround is to call the
* interrupt handler to clear any pending interrupt events.
* Note: this must be done after setting Ier.
*/
if(ie)
i8250interrupt(nil, uart);
}
static Uart*
i8250pnp(void)
{
return i8250uart;
}
static int
i8250getc(Uart* uart)
{
Ctlr *ctlr;
ctlr = uart->regs;
while(!(csr8r(ctlr, Lsr) & Dr))
delay(1);
return csr8r(ctlr, Rbr);
}
static void
i8250putc(Uart* uart, int c)
{
int i;
Ctlr *ctlr;
ctlr = uart->regs;
for(i = 0; !(csr8r(ctlr, Lsr) & Thre) && i < 128; i++)
delay(1);
csr8o(ctlr, Thr, (uchar)c);
for(i = 0; !(csr8r(ctlr, Lsr) & Thre) && i < 128; i++)
delay(1);
}
void
uartconsinit(void)
{
consuart = &i8250uart[0];
}
PhysUart i8250physuart = {
.name = "i8250",
.pnp = i8250pnp,
.enable = i8250enable,
.disable = i8250disable,
.kick = i8250kick,
.dobreak = i8250break,
.baud = i8250baud,
.bits = i8250bits,
.stop = i8250stop,
.parity = i8250parity,
.modemctl = i8250modemctl,
.rts = i8250rts,
.dtr = i8250dtr,
.status = i8250status,
.fifo = i8250fifo,
.getc = i8250getc,
.putc = i8250putc,
};