ps2_busywait.c (4844B)
1 /* 2 Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com> 3 4 This software is licensed with a Modified BSD License. 5 All of this is supposed to be Free Software, Open Source, DFSG-free, 6 GPL-compatible, and OK to use in both free and proprietary applications. 7 Additions and corrections to this file are welcome. 8 9 10 Redistribution and use in source and binary forms, with or without 11 modification, are permitted provided that the following conditions are met: 12 13 * Redistributions of source code must retain the above copyright 14 notice, this list of conditions and the following disclaimer. 15 16 * Redistributions in binary form must reproduce the above copyright 17 notice, this list of conditions and the following disclaimer in 18 the documentation and/or other materials provided with the 19 distribution. 20 21 * Neither the name of the copyright holders nor the names of 22 contributors may be used to endorse or promote products derived 23 from this software without specific prior written permission. 24 25 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 26 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 29 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 /* 39 * PS/2 protocol busywait version 40 */ 41 42 #include <stdbool.h> 43 #include "wait.h" 44 #include "ps2.h" 45 #include "ps2_io.h" 46 #include "debug.h" 47 48 #define WAIT(stat, us, err) \ 49 do { \ 50 if (!wait_##stat(us)) { \ 51 ps2_error = err; \ 52 goto ERROR; \ 53 } \ 54 } while (0) 55 56 uint8_t ps2_error = PS2_ERR_NONE; 57 58 void ps2_host_init(void) { 59 clock_init(); 60 data_init(); 61 62 // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20) 63 wait_ms(2500); 64 65 inhibit(); 66 } 67 68 uint8_t ps2_host_send(uint8_t data) { 69 bool parity = true; 70 ps2_error = PS2_ERR_NONE; 71 72 /* terminate a transmission if we have */ 73 inhibit(); 74 wait_us(100); // 100us [4]p.13, [5]p.50 75 76 /* 'Request to Send' and Start bit */ 77 data_lo(); 78 clock_hi(); 79 WAIT(clock_lo, 10000, 10); // 10ms [5]p.50 80 81 /* Data bit */ 82 for (uint8_t i = 0; i < 8; i++) { 83 wait_us(15); 84 if (data & (1 << i)) { 85 parity = !parity; 86 data_hi(); 87 } else { 88 data_lo(); 89 } 90 WAIT(clock_hi, 50, 2); 91 WAIT(clock_lo, 50, 3); 92 } 93 94 /* Parity bit */ 95 wait_us(15); 96 if (parity) { 97 data_hi(); 98 } else { 99 data_lo(); 100 } 101 WAIT(clock_hi, 50, 4); 102 WAIT(clock_lo, 50, 5); 103 104 /* Stop bit */ 105 wait_us(15); 106 data_hi(); 107 108 /* Ack */ 109 WAIT(data_lo, 50, 6); 110 WAIT(clock_lo, 50, 7); 111 112 /* wait for idle state */ 113 WAIT(clock_hi, 50, 8); 114 WAIT(data_hi, 50, 9); 115 116 inhibit(); 117 return ps2_host_recv_response(); 118 ERROR: 119 inhibit(); 120 return 0; 121 } 122 123 /* receive data when host want else inhibit communication */ 124 uint8_t ps2_host_recv_response(void) { 125 // Command may take 25ms/20ms at most([5]p.46, [3]p.21) 126 // 250 * 100us(wait for start bit in ps2_host_recv) 127 uint8_t data = 0; 128 uint8_t try = 250; 129 do { 130 data = ps2_host_recv(); 131 } while (try-- && ps2_error); 132 return data; 133 } 134 135 /* called after start bit comes */ 136 uint8_t ps2_host_recv(void) { 137 uint8_t data = 0; 138 bool parity = true; 139 ps2_error = PS2_ERR_NONE; 140 141 /* release lines(idle state) */ 142 idle(); 143 144 /* start bit [1] */ 145 WAIT(clock_lo, 100, 1); // TODO: this is enough? 146 WAIT(data_lo, 1, 2); 147 WAIT(clock_hi, 50, 3); 148 149 /* data [2-9] */ 150 for (uint8_t i = 0; i < 8; i++) { 151 WAIT(clock_lo, 50, 4); 152 if (data_in()) { 153 parity = !parity; 154 data |= (1 << i); 155 } 156 WAIT(clock_hi, 50, 5); 157 } 158 159 /* parity [10] */ 160 WAIT(clock_lo, 50, 6); 161 if (data_in() != parity) { 162 ps2_error = PS2_ERR_PARITY; 163 goto ERROR; 164 } 165 WAIT(clock_hi, 50, 7); 166 167 /* stop bit [11] */ 168 WAIT(clock_lo, 50, 8); 169 WAIT(data_hi, 1, 9); 170 WAIT(clock_hi, 50, 10); 171 172 inhibit(); 173 return data; 174 ERROR: 175 if (ps2_error > PS2_ERR_STARTBIT3) { 176 xprintf("x%02X\n", ps2_error); 177 } 178 inhibit(); 179 return 0; 180 } 181 182 /* send LED state to keyboard */ 183 void ps2_host_set_led(uint8_t led) { 184 ps2_host_send(0xED); 185 ps2_host_send(led); 186 }