root / prex-0.9.0 / bsp / drv / dev / serial / ns16550.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*-
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2 | * Copyright (c) 2009, Kohsuke Ohtani
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3 | * All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the author nor the names of any co-contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | */
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29 | |||
30 | /*
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31 | * ns16550.c - NS16550 serial driver
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32 | */
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33 | |||
34 | #include <driver.h> |
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35 | #include <tty.h> |
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36 | #include <serial.h> |
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37 | |||
38 | /* #define DEBUG_NS16550 1 */
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39 | |||
40 | #ifdef DEBUG_NS16550
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41 | #define DPRINTF(a) printf a
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42 | #else
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43 | #define DPRINTF(a)
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44 | #endif
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45 | |||
46 | #define COM_BASE CONFIG_NS16550_BASE
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47 | #define COM_IRQ CONFIG_NS16550_IRQ
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48 | |||
49 | /* Register offsets */
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50 | #define COM_RBR (COM_BASE + 0x00) /* receive buffer register */ |
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51 | #define COM_THR (COM_BASE + 0x00) /* transmit holding register */ |
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52 | #define COM_IER (COM_BASE + 0x01) /* interrupt enable register */ |
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53 | #define COM_FCR (COM_BASE + 0x02) /* FIFO control register */ |
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54 | #define COM_IIR (COM_BASE + 0x02) /* interrupt identification register */ |
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55 | #define COM_LCR (COM_BASE + 0x03) /* line control register */ |
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56 | #define COM_MCR (COM_BASE + 0x04) /* modem control register */ |
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57 | #define COM_LSR (COM_BASE + 0x05) /* line status register */ |
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58 | #define COM_MSR (COM_BASE + 0x06) /* modem status register */ |
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59 | #define COM_DLL (COM_BASE + 0x00) /* divisor latch LSB (LCR[7] = 1) */ |
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60 | #define COM_DLM (COM_BASE + 0x01) /* divisor latch MSB (LCR[7] = 1) */ |
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61 | |||
62 | /* Interrupt enable register */
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63 | #define IER_RDA 0x01 /* enable receive data available */ |
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64 | #define IER_THRE 0x02 /* enable transmitter holding register empty */ |
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65 | #define IER_RLS 0x04 /* enable recieve line status */ |
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66 | #define IER_RMS 0x08 /* enable receive modem status */ |
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67 | |||
68 | /* Interrupt identification register */
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69 | #define IIR_MSR 0x00 /* modem status change */ |
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70 | #define IIR_IP 0x01 /* 0 when interrupt pending */ |
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71 | #define IIR_TXB 0x02 /* transmitter holding register empty */ |
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72 | #define IIR_RXB 0x04 /* received data available */ |
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73 | #define IIR_LSR 0x06 /* line status change */ |
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74 | #define IIR_MASK 0x07 /* mask off just the meaningful bits */ |
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75 | |||
76 | /* line status register */
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77 | #define LSR_RCV_FIFO 0x80 |
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78 | #define LSR_TSRE 0x40 /* Transmitter empty: byte sent */ |
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79 | #define LSR_TXRDY 0x20 /* Transmitter buffer empty */ |
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80 | #define LSR_BI 0x10 /* Break detected */ |
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81 | #define LSR_FE 0x08 /* Framing error: bad stop bit */ |
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82 | #define LSR_PE 0x04 /* Parity error */ |
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83 | #define LSR_OE 0x02 /* Overrun, lost incoming byte */ |
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84 | #define LSR_RXRDY 0x01 /* Byte ready in Receive Buffer */ |
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85 | #define LSR_RCV_MASK 0x1f /* Mask for incoming data or error */ |
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86 | |||
87 | /* Forward functions */
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88 | static int ns16550_probe(struct driver *); |
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89 | static int ns16550_init(struct driver *); |
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90 | |||
91 | static void ns16550_xmt_char(struct serial_port *, char); |
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92 | static char ns16550_rcv_char(struct serial_port *); |
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93 | static void ns16550_set_poll(struct serial_port *, int); |
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94 | static void ns16550_start(struct serial_port *); |
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95 | static void ns16550_stop(struct serial_port *); |
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96 | |||
97 | |||
98 | struct driver ns16550_driver = {
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99 | /* name */ "ns16550", |
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100 | /* devops */ NULL, |
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101 | /* devsz */ 0, |
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102 | /* flags */ 0, |
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103 | /* probe */ ns16550_probe,
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104 | /* init */ ns16550_init,
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105 | /* unload */ NULL, |
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106 | }; |
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107 | |||
108 | static struct serial_ops ns16550_ops = { |
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109 | /* xmt_char */ ns16550_xmt_char,
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110 | /* rcv_char */ ns16550_rcv_char,
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111 | /* set_poll */ ns16550_set_poll,
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112 | /* start */ ns16550_start,
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113 | /* stop */ ns16550_stop,
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114 | }; |
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115 | |||
116 | |||
117 | static struct serial_port ns16550_port; |
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118 | |||
119 | |||
120 | static void |
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121 | ns16550_xmt_char(struct serial_port *sp, char c) |
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122 | { |
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123 | |||
124 | while (!(bus_read_8(COM_LSR) & LSR_TXRDY))
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125 | ; |
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126 | bus_write_8(COM_THR, c); |
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127 | } |
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128 | |||
129 | static char |
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130 | ns16550_rcv_char(struct serial_port *sp)
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131 | { |
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132 | |||
133 | while (!(bus_read_8(COM_LSR) & LSR_RXRDY))
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134 | ; |
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135 | return bus_read_8(COM_RBR);
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136 | } |
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137 | |||
138 | static void |
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139 | ns16550_set_poll(struct serial_port *sp, int on) |
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140 | { |
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141 | |||
142 | if (on) {
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143 | /* Disable interrupt for polling mode. */
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144 | bus_write_8(COM_IER, 0x00);
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145 | } else {
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146 | /* enable interrupt again */
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147 | bus_write_8(COM_IER, IER_RDA|IER_THRE|IER_RLS); |
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148 | } |
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149 | } |
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150 | |||
151 | static int |
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152 | ns16550_isr(void *arg)
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153 | { |
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154 | struct serial_port *sp = arg;
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155 | |||
156 | switch (bus_read_8(COM_IIR) & IIR_MASK) {
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157 | case IIR_MSR: /* Modem status change */ |
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158 | break;
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159 | case IIR_LSR: /* Line status change */ |
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160 | bus_read_8(COM_LSR); |
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161 | break;
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162 | case IIR_TXB: /* Transmitter holding register empty */ |
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163 | serial_xmt_done(sp); |
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164 | break;
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165 | case IIR_RXB: /* Received data available */ |
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166 | bus_read_8(COM_LSR); |
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167 | serial_rcv_char(sp, bus_read_8(COM_RBR)); |
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168 | break;
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169 | } |
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170 | return 0; |
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171 | } |
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172 | |||
173 | static void |
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174 | ns16550_start(struct serial_port *sp)
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175 | { |
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176 | int s;
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177 | |||
178 | bus_write_8(COM_IER, 0x00); /* Disable interrupt */ |
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179 | bus_write_8(COM_LCR, 0x80); /* Access baud rate */ |
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180 | bus_write_8(COM_DLL, 0x01); /* 115200 baud */ |
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181 | bus_write_8(COM_DLM, 0x00);
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182 | bus_write_8(COM_LCR, 0x03); /* N, 8, 1 */ |
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183 | bus_write_8(COM_FCR, 0x06); /* Disable & clear FIFO */ |
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184 | |||
185 | sp->irq = irq_attach(COM_IRQ, IPL_COMM, 0, ns16550_isr,
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186 | IST_NONE, sp); |
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187 | |||
188 | s = splhigh(); |
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189 | bus_write_8(COM_MCR, 0x0b); /* Enable OUT2 interrupt */ |
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190 | bus_write_8(COM_IER, IER_RDA|IER_THRE|IER_RLS); /* Enable interrupt */
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191 | bus_read_8(COM_IIR); |
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192 | splx(s); |
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193 | } |
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194 | |||
195 | static void |
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196 | ns16550_stop(struct serial_port *sp)
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197 | { |
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198 | |||
199 | /* Disable all interrupts */
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200 | bus_write_8(COM_IER, 0x00);
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201 | } |
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202 | |||
203 | |||
204 | static int |
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205 | ns16550_probe(struct driver *self)
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206 | { |
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207 | |||
208 | if (bus_read_8(COM_LSR) == 0xff) |
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209 | return ENXIO; /* Port is disabled */ |
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210 | return 0; |
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211 | } |
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212 | |||
213 | static int |
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214 | ns16550_init(struct driver *self)
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215 | { |
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216 | |||
217 | serial_attach(&ns16550_ops, &ns16550_port); |
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218 | return 0; |
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219 | } |