1 /* 2 * udbg for for NS16550 compatable serial ports 3 * 4 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp 5 * 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. 10 */ 11 #include <linux/types.h> 12 #include <asm/udbg.h> 13 #include <asm/io.h> 14 15 extern u8 real_readb(volatile u8 __iomem *addr); 16 extern void real_writeb(u8 data, volatile u8 __iomem *addr); 17 18 struct NS16550 { 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 */ 28 }; 29 30 #define thr rbr 31 #define iir fcr 32 #define dll rbr 33 #define dlm ier 34 #define dlab lcr 35 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 */ 44 45 #define LCR_DLAB 0x80 46 47 static volatile struct NS16550 __iomem *udbg_comport; 48 49 static void udbg_550_putc(char c) 50 { 51 if (udbg_comport) { 52 while ((in_8(&udbg_comport->lsr) & LSR_THRE) == 0) 53 /* wait for idle */; 54 out_8(&udbg_comport->thr, c); 55 if (c == '\n') 56 udbg_550_putc('\r'); 57 } 58 } 59 60 static int udbg_550_getc_poll(void) 61 { 62 if (udbg_comport) { 63 if ((in_8(&udbg_comport->lsr) & LSR_DR) != 0) 64 return in_8(&udbg_comport->rbr); 65 else 66 return -1; 67 } 68 return -1; 69 } 70 71 static int udbg_550_getc(void) 72 { 73 if (udbg_comport) { 74 while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0) 75 /* wait for char */; 76 return in_8(&udbg_comport->rbr); 77 } 78 return -1; 79 } 80 81 void udbg_init_uart(void __iomem *comport, unsigned int speed, 82 unsigned int clock) 83 { 84 unsigned int dll, base_bauds = clock / 16; 85 86 if (speed == 0) 87 speed = 9600; 88 dll = base_bauds / speed; 89 90 if (comport) { 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); 100 /* RTS/DTR */ 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; 107 } 108 } 109 110 unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock) 111 { 112 unsigned int dll, dlm, divisor, prescaler, speed; 113 u8 old_lcr; 114 volatile struct NS16550 __iomem *port = comport; 115 116 old_lcr = in_8(&port->lcr); 117 118 /* select divisor latch registers. */ 119 out_8(&port->lcr, LCR_DLAB); 120 121 /* now, read the divisor */ 122 dll = in_8(&port->dll); 123 dlm = in_8(&port->dlm); 124 divisor = dlm << 8 | dll; 125 126 /* check prescaling */ 127 if (in_8(&port->mcr) & 0x80) 128 prescaler = 4; 129 else 130 prescaler = 1; 131 132 /* restore the LCR */ 133 out_8(&port->lcr, old_lcr); 134 135 /* calculate speed */ 136 speed = (clock / prescaler) / (divisor * 16); 137 138 /* sanity check */ 139 if (speed < 0 || speed > (clock / 16)) 140 speed = 9600; 141 142 return speed; 143 } 144 145 #ifdef CONFIG_PPC_MAPLE 146 void udbg_maple_real_putc(char c) 147 { 148 if (udbg_comport) { 149 while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0) 150 /* wait for idle */; 151 real_writeb(c, &udbg_comport->thr); eieio(); 152 if (c == '\n') 153 udbg_maple_real_putc('\r'); 154 } 155 } 156 157 void __init udbg_init_maple_realmode(void) 158 { 159 udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8; 160 161 udbg_putc = udbg_maple_real_putc; 162 udbg_getc = NULL; 163 udbg_getc_poll = NULL; 164 } 165 #endif /* CONFIG_PPC_MAPLE */ 166