2 * udbg for for NS16550 compatable serial ports
4 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
11 #include <linux/types.h>
15 extern u8 real_readb(volatile u8 __iomem *addr);
16 extern void real_writeb(u8 data, volatile u8 __iomem *addr);
19 /* this struct must be packed */
20 unsigned char rbr; /* 0 */
21 unsigned char ier; /* 1 */
22 unsigned char fcr; /* 2 */
23 unsigned char lcr; /* 3 */
24 unsigned char mcr; /* 4 */
25 unsigned char lsr; /* 5 */
26 unsigned char msr; /* 6 */
27 unsigned char scr; /* 7 */
36 #define LSR_DR 0x01 /* Data ready */
37 #define LSR_OE 0x02 /* Overrun */
38 #define LSR_PE 0x04 /* Parity error */
39 #define LSR_FE 0x08 /* Framing error */
40 #define LSR_BI 0x10 /* Break */
41 #define LSR_THRE 0x20 /* Xmit holding register empty */
42 #define LSR_TEMT 0x40 /* Xmitter empty */
43 #define LSR_ERR 0x80 /* Error */
47 static volatile struct NS16550 __iomem *udbg_comport;
49 static void udbg_550_putc(char c)
52 while ((in_8(&udbg_comport->lsr) & LSR_THRE) == 0)
54 out_8(&udbg_comport->thr, c);
60 static int udbg_550_getc_poll(void)
63 if ((in_8(&udbg_comport->lsr) & LSR_DR) != 0)
64 return in_8(&udbg_comport->rbr);
71 static int udbg_550_getc(void)
74 while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0)
76 return in_8(&udbg_comport->rbr);
81 void udbg_init_uart(void __iomem *comport, unsigned int speed,
84 unsigned int dll, base_bauds = clock / 16;
88 dll = base_bauds / speed;
91 udbg_comport = (struct NS16550 __iomem *)comport;
92 out_8(&udbg_comport->lcr, 0x00);
93 out_8(&udbg_comport->ier, 0xff);
94 out_8(&udbg_comport->ier, 0x00);
95 out_8(&udbg_comport->lcr, LCR_DLAB);
96 out_8(&udbg_comport->dll, dll & 0xff);
97 out_8(&udbg_comport->dlm, dll >> 8);
98 /* 8 data, 1 stop, no parity */
99 out_8(&udbg_comport->lcr, 0x03);
101 out_8(&udbg_comport->mcr, 0x03);
102 /* Clear & enable FIFOs */
103 out_8(&udbg_comport->fcr ,0x07);
104 udbg_putc = udbg_550_putc;
105 udbg_getc = udbg_550_getc;
106 udbg_getc_poll = udbg_550_getc_poll;
110 unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock)
112 unsigned int dll, dlm, divisor, prescaler, speed;
114 volatile struct NS16550 __iomem *port = comport;
116 old_lcr = in_8(&port->lcr);
118 /* select divisor latch registers. */
119 out_8(&port->lcr, LCR_DLAB);
121 /* now, read the divisor */
122 dll = in_8(&port->dll);
123 dlm = in_8(&port->dlm);
124 divisor = dlm << 8 | dll;
126 /* check prescaling */
127 if (in_8(&port->mcr) & 0x80)
132 /* restore the LCR */
133 out_8(&port->lcr, old_lcr);
135 /* calculate speed */
136 speed = (clock / prescaler) / (divisor * 16);
139 if (speed < 0 || speed > (clock / 16))
145 #ifdef CONFIG_PPC_MAPLE
146 void udbg_maple_real_putc(char c)
149 while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
151 real_writeb(c, &udbg_comport->thr); eieio();
153 udbg_maple_real_putc('\r');
157 void __init udbg_init_maple_realmode(void)
159 udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8;
161 udbg_putc = udbg_maple_real_putc;
163 udbg_getc_poll = NULL;
165 #endif /* CONFIG_PPC_MAPLE */