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; 85 86 if (clock == 0) 87 clock = 1843200; 88 if (speed == 0) 89 speed = 9600; 90 91 base_bauds = clock / 16; 92 dll = base_bauds / speed; 93 94 if (comport) { 95 udbg_comport = (struct NS16550 __iomem *)comport; 96 out_8(&udbg_comport->lcr, 0x00); 97 out_8(&udbg_comport->ier, 0xff); 98 out_8(&udbg_comport->ier, 0x00); 99 out_8(&udbg_comport->lcr, LCR_DLAB); 100 out_8(&udbg_comport->dll, dll & 0xff); 101 out_8(&udbg_comport->dlm, dll >> 8); 102 /* 8 data, 1 stop, no parity */ 103 out_8(&udbg_comport->lcr, 0x03); 104 /* RTS/DTR */ 105 out_8(&udbg_comport->mcr, 0x03); 106 /* Clear & enable FIFOs */ 107 out_8(&udbg_comport->fcr ,0x07); 108 udbg_putc = udbg_550_putc; 109 udbg_getc = udbg_550_getc; 110 udbg_getc_poll = udbg_550_getc_poll; 111 } 112 } 113 114 unsigned int udbg_probe_uart_speed(void __iomem *comport, unsigned int clock) 115 { 116 unsigned int dll, dlm, divisor, prescaler, speed; 117 u8 old_lcr; 118 volatile struct NS16550 __iomem *port = comport; 119 120 old_lcr = in_8(&port->lcr); 121 122 /* select divisor latch registers. */ 123 out_8(&port->lcr, LCR_DLAB); 124 125 /* now, read the divisor */ 126 dll = in_8(&port->dll); 127 dlm = in_8(&port->dlm); 128 divisor = dlm << 8 | dll; 129 130 /* check prescaling */ 131 if (in_8(&port->mcr) & 0x80) 132 prescaler = 4; 133 else 134 prescaler = 1; 135 136 /* restore the LCR */ 137 out_8(&port->lcr, old_lcr); 138 139 /* calculate speed */ 140 speed = (clock / prescaler) / (divisor * 16); 141 142 /* sanity check */ 143 if (speed < 0 || speed > (clock / 16)) 144 speed = 9600; 145 146 return speed; 147 } 148 149 #ifdef CONFIG_PPC_MAPLE 150 void udbg_maple_real_putc(char c) 151 { 152 if (udbg_comport) { 153 while ((real_readb(&udbg_comport->lsr) & LSR_THRE) == 0) 154 /* wait for idle */; 155 real_writeb(c, &udbg_comport->thr); eieio(); 156 if (c == '\n') 157 udbg_maple_real_putc('\r'); 158 } 159 } 160 161 void __init udbg_init_maple_realmode(void) 162 { 163 udbg_comport = (volatile struct NS16550 __iomem *)0xf40003f8; 164 165 udbg_putc = udbg_maple_real_putc; 166 udbg_getc = NULL; 167 udbg_getc_poll = NULL; 168 } 169 #endif /* CONFIG_PPC_MAPLE */ 170