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/config.h> 12 #include <linux/types.h> 13 #include <asm/udbg.h> 14 #include <asm/io.h> 15 16 extern u8 real_readb(volatile u8 __iomem *addr); 17 extern void real_writeb(u8 data, volatile u8 __iomem *addr); 18 19 struct NS16550 { 20 /* this struct must be packed */ 21 unsigned char rbr; /* 0 */ 22 unsigned char ier; /* 1 */ 23 unsigned char fcr; /* 2 */ 24 unsigned char lcr; /* 3 */ 25 unsigned char mcr; /* 4 */ 26 unsigned char lsr; /* 5 */ 27 unsigned char msr; /* 6 */ 28 unsigned char scr; /* 7 */ 29 }; 30 31 #define thr rbr 32 #define iir fcr 33 #define dll rbr 34 #define dlm ier 35 #define dlab lcr 36 37 #define LSR_DR 0x01 /* Data ready */ 38 #define LSR_OE 0x02 /* Overrun */ 39 #define LSR_PE 0x04 /* Parity error */ 40 #define LSR_FE 0x08 /* Framing error */ 41 #define LSR_BI 0x10 /* Break */ 42 #define LSR_THRE 0x20 /* Xmit holding register empty */ 43 #define LSR_TEMT 0x40 /* Xmitter empty */ 44 #define LSR_ERR 0x80 /* Error */ 45 46 #define LCR_DLAB 0x80 47 48 static volatile struct NS16550 __iomem *udbg_comport; 49 50 static void udbg_550_putc(char c) 51 { 52 if (udbg_comport) { 53 while ((in_8(&udbg_comport->lsr) & LSR_THRE) == 0) 54 /* wait for idle */; 55 out_8(&udbg_comport->thr, c); 56 if (c == '\n') 57 udbg_550_putc('\r'); 58 } 59 } 60 61 static int udbg_550_getc_poll(void) 62 { 63 if (udbg_comport) { 64 if ((in_8(&udbg_comport->lsr) & LSR_DR) != 0) 65 return in_8(&udbg_comport->rbr); 66 else 67 return -1; 68 } 69 return -1; 70 } 71 72 static int udbg_550_getc(void) 73 { 74 if (udbg_comport) { 75 while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0) 76 /* wait for char */; 77 return in_8(&udbg_comport->rbr); 78 } 79 return -1; 80 } 81 82 void udbg_init_uart(void __iomem *comport, unsigned int speed, 83 unsigned int clock) 84 { 85 unsigned int dll, base_bauds = clock / 16; 86 87 if (speed == 0) 88 speed = 9600; 89 dll = base_bauds / speed; 90 91 if (comport) { 92 udbg_comport = (struct NS16550 __iomem *)comport; 93 out_8(&udbg_comport->lcr, 0x00); 94 out_8(&udbg_comport->ier, 0xff); 95 out_8(&udbg_comport->ier, 0x00); 96 out_8(&udbg_comport->lcr, LCR_DLAB); 97 out_8(&udbg_comport->dll, dll & 0xff); 98 out_8(&udbg_comport->dlm, dll >> 8); 99 /* 8 data, 1 stop, no parity */ 100 out_8(&udbg_comport->lcr, 0x03); 101 /* RTS/DTR */ 102 out_8(&udbg_comport->mcr, 0x03); 103 /* Clear & enable FIFOs */ 104 out_8(&udbg_comport->fcr ,0x07); 105 udbg_putc = udbg_550_putc; 106 udbg_getc = udbg_550_getc; 107 udbg_getc_poll = udbg_550_getc_poll; 108 } 109 } 110 111 unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock) 112 { 113 unsigned int dll, dlm, divisor, prescaler, speed; 114 u8 old_lcr; 115 volatile struct NS16550 __iomem *port = comport; 116 117 old_lcr = in_8(&port->lcr); 118 119 /* select divisor latch registers. */ 120 out_8(&port->lcr, LCR_DLAB); 121 122 /* now, read the divisor */ 123 dll = in_8(&port->dll); 124 dlm = in_8(&port->dlm); 125 divisor = dlm << 8 | dll; 126 127 /* check prescaling */ 128 if (in_8(&port->mcr) & 0x80) 129 prescaler = 4; 130 else 131 prescaler = 1; 132 133 /* restore the LCR */ 134 out_8(&port->lcr, old_lcr); 135 136 /* calculate speed */ 137 speed = (clock / prescaler) / (divisor * 16); 138 139 /* sanity check */ 140 if (speed < 0 || speed > (clock / 16)) 141 speed = 9600; 142 143 return speed; 144 } 145 146 #ifdef CONFIG_PPC_MAPLE 147 void udbg_maple_real_putc(char c) 148 { 149 if (udbg_comport) { 150 while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0) 151 /* wait for idle */; 152 real_writeb(c, &udbg_comport->thr); eieio(); 153 if (c == '\n') 154 udbg_maple_real_putc('\r'); 155 } 156 } 157 158 void __init udbg_init_maple_realmode(void) 159 { 160 udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8; 161 162 udbg_putc = udbg_maple_real_putc; 163 udbg_getc = NULL; 164 udbg_getc_poll = NULL; 165 } 166 #endif /* CONFIG_PPC_MAPLE */ 167