/*
* udbg for for NS16550 compatable serial ports
*
* Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/types.h>
#include <asm/udbg.h>
#include <asm/io.h>
extern u8 real_readb(volatile u8 __iomem *addr);
extern void real_writeb(u8 data, volatile u8 __iomem *addr);
struct NS16550 {
/* this struct must be packed */
unsigned char rbr; /* 0 */
unsigned char ier; /* 1 */
unsigned char fcr; /* 2 */
unsigned char lcr; /* 3 */
unsigned char mcr; /* 4 */
unsigned char lsr; /* 5 */
unsigned char msr; /* 6 */
unsigned char scr; /* 7 */
};
#define thr rbr
#define iir fcr
#define dll rbr
#define dlm ier
#define dlab lcr
#define LSR_DR 0x01 /* Data ready */
#define LSR_OE 0x02 /* Overrun */
#define LSR_PE 0x04 /* Parity error */
#define LSR_FE 0x08 /* Framing error */
#define LSR_BI 0x10 /* Break */
#define LSR_THRE 0x20 /* Xmit holding register empty */
#define LSR_TEMT 0x40 /* Xmitter empty */
#define LSR_ERR 0x80 /* Error */
#define LCR_DLAB 0x80
static volatile struct NS16550 __iomem *udbg_comport;
static void udbg_550_putc(char c)
{
if (udbg_comport) {
while ((in_8(&udbg_comport->lsr) & LSR_THRE) == 0)
/* wait for idle */;
out_8(&udbg_comport->thr, c);
if (c == '\n')
udbg_550_putc('\r');
}
}
static int udbg_550_getc_poll(void)
{
if (udbg_comport) {
if ((in_8(&udbg_comport->lsr) & LSR_DR) != 0)
return in_8(&udbg_comport->rbr);
else
return -1;
}
return -1;
}
static int udbg_550_getc(void)
{
if (udbg_comport) {
while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0)
/* wait for char */;
return in_8(&udbg_comport->rbr);
}
return -1;
}
void udbg_init_uart(void __iomem *comport, unsigned int speed,
unsigned int clock)
{
unsigned int dll, base_bauds = clock / 16;
if (speed == 0)
speed = 9600;
dll = base_bauds / speed;
if (comport) {
udbg_comport = (struct NS16550 __iomem *)comport;
out_8(&udbg_comport->lcr, 0x00);
out_8(&udbg_comport->ier, 0xff);
out_8(&udbg_comport->ier, 0x00);
out_8(&udbg_comport->lcr, LCR_DLAB);
out_8(&udbg_comport->dll, dll & 0xff);
out_8(&udbg_comport->dlm, dll >> 8);
/* 8 data, 1 stop, no parity */
out_8(&udbg_comport->lcr, 0x03);
/* RTS/DTR */
out_8(&udbg_comport->mcr, 0x03);
/* Clear & enable FIFOs */
out_8(&udbg_comport->fcr ,0x07);
udbg_putc = udbg_550_putc;
udbg_getc = udbg_550_getc;
udbg_getc_poll = udbg_550_getc_poll;
}
}
unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock)
{
unsigned int dll, dlm, divisor, prescaler, speed;
u8 old_lcr;
volatile struct NS16550 __iomem *port = comport;
old_lcr = in_8(&port->lcr);
/* select divisor latch registers. */
out_8(&port->lcr, LCR_DLAB);
/* now, read the divisor */
dll = in_8(&port->dll);
dlm = in_8(&port->dlm);
divisor = dlm << 8 | dll;
/* check prescaling */
if (in_8(&port->mcr) & 0x80)
prescaler = 4;
else
prescaler = 1;
/* restore the LCR */
out_8(&port->lcr, old_lcr);
/* calculate speed */
speed = (clock / prescaler) / (divisor * 16);
/* sanity check */
if (speed < 0 || speed > (clock / 16))
speed = 9600;
return speed;
}
#ifdef CONFIG_PPC_MAPLE
void udbg_maple_real_putc(char c)
{
if (udbg_comport) {
while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
/* wait for idle */;
real_writeb(c, &udbg_comport->thr); eieio();
if (c == '\n')
udbg_maple_real_putc('\r');
}
}
void __init udbg_init_maple_realmode(void)
{
udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8;
udbg_putc = udbg_maple_real_putc;
udbg_getc = NULL;
udbg_getc_poll = NULL;
}
#endif /* CONFIG_PPC_MAPLE */
