1 | /* |
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2 | * soclib_tty.c - soclib_tty driver definition (used in the TSAR_IOB architecture). |
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3 | * |
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4 | * Author Alain Greiner (2016,2017,2018) |
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5 | * |
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6 | * Copyright (c) UPMC Sorbonne Universites |
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7 | * |
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8 | * This file is part of ALMOS-MKH. |
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9 | * |
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10 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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11 | * under the terms of the GNU General Public License as published by |
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12 | * the Free Software Foundation; version 2.0 of the License. |
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13 | * |
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14 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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15 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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17 | * General Public License for more details. |
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18 | * |
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19 | * You should have received a copy of the GNU General Public License |
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20 | * along with ALMOS-kernel; if not, write to the Free Software Foundation, |
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21 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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22 | */ |
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23 | |
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24 | #include <dev_txt.h> |
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25 | #include <chdev.h> |
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26 | |
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27 | |
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28 | /**************************************************************************************** |
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29 | * This driver supports the vci_tty_tsar component. |
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30 | * |
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31 | * 1) This hardware component handles several hardware channels, supporting directly |
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32 | * several kernel TXT channels. |
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33 | * 2) For received characters, the hardware support one RX_IRQ, and one bit |
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34 | * in the STATUS register to signal that the READ register is full. |
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35 | * 3) For transmitted characters, the hardware supports one RX_IRQ, and one bit |
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36 | * in STATUS register to signal that the WRITE register is empty. |
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37 | * |
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38 | * It implements the generic TXT device API: |
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39 | * - transfer one single character from TTY to command "buffer" if to_mem is non-zero. |
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40 | * - transfer "count" characters from command "buffer" to TTY if to_mem is zero. |
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41 | * |
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42 | * It handles asynchronous control characters (^C / ^Z), that are translated to signals |
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43 | * transmited to the TXT owner process (foreground process). |
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44 | * |
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45 | * This driver implements one TX_FIFO for the transmited characters, writen by the "cmd" |
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46 | * function, and read by the "isr" function). |
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47 | * This driver implements one RX_FIFO for the received characters, writen by the "isr" |
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48 | * function, and read by the "cmd" function). |
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49 | ***************************************************************************************/ |
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50 | |
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51 | /**************************************************************************************** |
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52 | * SOCLIB_TTY registers offsets |
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53 | ***************************************************************************************/ |
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54 | |
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55 | #define TTY_WRITE 0 |
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56 | #define TTY_STATUS 1 |
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57 | #define TTY_READ 2 |
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58 | #define TTY_RX_IRQ_ENABLE 3 |
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59 | #define TTY_TX_IRQ_ENABLE 4 |
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60 | |
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61 | #define TTY_SPAN 8 // number of registers per channel |
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62 | |
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63 | /**************************************************************************************** |
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64 | * masks for TTY_STATUS_REG |
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65 | ***************************************************************************************/ |
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66 | |
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67 | #define TTY_STATUS_RX_FULL 1 // TTY_READ_REG full if 1 |
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68 | #define TTY_STATUS_TX_FULL 2 // TTY_WRITE_REG full if 1 |
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69 | |
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70 | /**************************************************************************************** |
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71 | * This structure is used for both the RX_FIFO and the TX_FIFO. |
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72 | ***************************************************************************************/ |
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73 | |
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74 | #define TTY_FIFO_DEPTH 128 |
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75 | |
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76 | typedef struct tty_fifo_s |
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77 | { |
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78 | char data[TTY_FIFO_DEPTH]; // one char per slot |
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79 | unsigned int ptr; // next free slot index |
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80 | unsigned int ptw; // next full slot index |
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81 | unsigned int sts; // number of full slots |
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82 | } |
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83 | tty_fifo_t; |
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84 | |
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85 | /**************************************************************************************** |
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86 | * This function masks both the TTY_RX and TTY_TX IRQs. |
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87 | * These IRQs are unmasked by the soclib_tty_cmd() function. |
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88 | **************************************************************************************** |
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89 | * @ chdev : pointer on the TXT chdev descriptor. |
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90 | ***************************************************************************************/ |
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91 | void soclib_tty_init( chdev_t * chdev ); |
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92 | |
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93 | /**************************************************************************************** |
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94 | * This function implements both the TXT_READ & TXT_WRITE commands registered in the |
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95 | * client thread descriptor (in the txt_cmd field), even if ALMOS-MKH defines two |
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96 | * different chdevs (and consequently two diffeerent server threads) for the RX and TX |
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97 | * directions. The client thread is identified by the <thread_xp> argument. |
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98 | * These functions are supposed to be called by the server thread associated at a |
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99 | * given TXT channel for a given direction (TX or RX). |
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100 | * Depending on the command type, it access the TX_FIFO or RX_FIFO, and blocks the TXT |
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101 | * device server thread on the THREAD_BLOCKED_DEV_ISR, if the RX_FIFO is empty (for a |
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102 | * READ), or if the TX_FIFO is full for a WRITE). |
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103 | * The actual transfer between the FIFOs and the TTY device registers is done by the ISR. |
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104 | * **************************************************************************************** |
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105 | * @ thread_xp : extended pointer on client thread descriptor. |
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106 | ***************************************************************************************/ |
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107 | void soclib_tty_cmd( xptr_t thread_xp ); |
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108 | |
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109 | /**************************************************************************************** |
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110 | * This function implements the TXT_SYNC_WRITE command registered in the txt_aux_t |
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111 | * structure, using a busy waiting policy, without using the TTY IRQ. |
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112 | * It is used by the kernel do display debug messages on TXT0 terminal, without |
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113 | * interference with another TXT access to another terminal done by the same thread. |
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114 | **************************************************************************************** |
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115 | * @ thread_xp : pointer on the txt_aux_t structure containing the arguments. |
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116 | ***************************************************************************************/ |
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117 | void soclib_tty_aux( void * args ); |
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118 | |
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119 | /**************************************************************************************** |
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120 | * This ISR is executed to handle both the TTY_TX_IRQ and the TTY_RX_IRQ, even if |
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121 | * there is two different channel devices for TX and RX transfers. |
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122 | * |
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123 | * As the <chdev> argument is a local pointer, this ISR is always executed by a core |
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124 | * that is in the same cluster as the core running the DEV server thread. |
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125 | * |
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126 | * - The RX_IRQ is activated as soon as the TTY_STATUS_RX_FULL bit is 1 in the |
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127 | * TTY_STATUS register, when the TTY_RX_IRQ_ENABLE is non zero, indicating that |
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128 | * the TTY_READ buffer is full and can be read. |
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129 | * - The TX_IRQ is activated as soon as the TTY_STATUS_TX_FULL bit is 0 in the |
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130 | * TTY_STATUS register, when the TTY_TX_IRQ_ENABLE is non zero, indicating that |
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131 | * the TTY_WRITE buffer is empty, and can be written. |
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132 | * |
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133 | * The RX_IRQ is always enabled to catch the control characters (^Z / ^C), |
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134 | * but the TX_IRQ is dynamically enabled by the TXT_WRITE command, and disabled when |
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135 | * the command is completed. |
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136 | * |
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137 | * For normal characters The ISR uses two private TTY_RX and TTY_TX software FIFOs |
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138 | * (two FIFOs per channel) to communicates with the DEV server thread executing the |
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139 | * soclib_tty_cmd() function. |
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140 | |
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141 | * For an RX transfer, this ISR executes a while loop moving bytes until the source |
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142 | * TTY_READ buffer is empty: |
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143 | * 1) The ISR read one byte from the TTY_READ register and acknowledge the RX_IRQ. |
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144 | * 2) if the byte is a ^Z character, it uses a multicast RPC to block all treads of |
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145 | * the TXT owner process, and transfer TXT ownership to another process of the group. |
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146 | * 3) if the byte is a ^C character, it removes the process from the TXT group, and send |
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147 | * a multicast RPC to delete all threads of the TXT owner process. |
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148 | * 4) if the byte is a normal character and the destination TTY_RX_FIFO is not full, |
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149 | * it writes the byte to this FIFO, unblock the TXT_RX server thread, and send an IPI |
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150 | * to this server thread (only if it is running on another core than the ISR). |
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151 | * 5) It discards the byte if the TTY_RX_FIFO is full, with a warning message on TXT0. |
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152 | * |
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153 | * For a TX transfer, this ISR executes a while loop moving bytes until the source |
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154 | * TTY_TX_FIFO is empty: |
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155 | * 1) if the destination TTY_WRITE register is not full, it moves the byte from the |
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156 | * TTY_TX_FIFO to the TTY_WRITE register. |
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157 | * 2) if the TTY_WRITE register is full, it polls (busy waiting) the TTY_STATUS register, |
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158 | * until the TTY_WRITE register is empty. |
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159 | * 3) when the source TTY_TX_FIFO is empty, this ISR disable the TTY_TX_IRQ, unblock |
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160 | * the TXT_TX server thread, and send an IPI to this server thread (only if it is |
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161 | * running on another core than the ISR). |
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162 | **************************************************************************************** |
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163 | * @ chdev : local pointer on TXT chdev descriptor. |
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164 | ***************************************************************************************/ |
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165 | void soclib_tty_isr( chdev_t * chdev ); |
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166 | |
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