protocol/ps2_busywait.c

   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 #include <stdbool.h>
  39 #include <util/delay.h>
  40 #include "ps2.h"
  41 #include "debug.h"
  42
  43
  44 /*
  45  * PS/2 protocol busywait version
  46  */
  47
  48 #define WAIT(stat, us, err) do { \
  49     if (!wait_##stat(us)) { \
  50         ps2_error = err; \
  51         goto ERROR; \
  52     } \
  53 } while (0)
  54
  55 uint8_t ps2_error = PS2_ERR_NONE;
  56
  57
  58 void ps2_host_init(void)
  59 {
  60     // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
  61     _delay_ms(2500);
  62
  63     inhibit();
  64 }
  65
  66 uint8_t ps2_host_send(uint8_t data)
  67 {
  68     uint8_t res = 0;
  69     bool parity = true;
  70     ps2_error = PS2_ERR_NONE;
  71     /* terminate a transmission if we have */
  72     inhibit();
  73     _delay_us(200); // at least 100us
  74
  75     /* start bit [1] */
  76     data_lo();
  77     clock_hi();
  78     WAIT(clock_lo, 20000, 10);   // may take 15ms at most until device starts clocking
  79     /* data [2-9] */
  80     for (uint8_t i = 0; i < 8; i++) {
  81         _delay_us(15);
  82         if (data&(1<<i)) {
  83             parity = !parity;
  84             data_hi();
  85         } else {
  86             data_lo();
  87         }
  88         WAIT(clock_hi, 50, 2);
  89         WAIT(clock_lo, 50, 3);
  90     }
  91     /* parity [10] */
  92     _delay_us(15);
  93     if (parity) { data_hi(); } else { data_lo(); }
  94     WAIT(clock_hi, 50, 4);
  95     WAIT(clock_lo, 50, 5);
  96     /* stop bit [11] */
  97     _delay_us(15);
  98     data_hi();
  99     /* ack [12] */
 100     WAIT(data_lo, 50, 6);
 101     WAIT(clock_lo, 50, 7);
 102
 103     /* wait for idle state */
 104     WAIT(clock_hi, 50, 8);
 105     WAIT(data_hi, 50, 9);
 106
 107     res = ps2_host_recv_response();
 108 ERROR:
 109     inhibit();
 110     return res;
 111 }
 112
 113 /* receive data when host want else inhibit communication */
 114 uint8_t ps2_host_recv_response(void)
 115 {
 116     // TODO:
 117     // Command might take 20ms to response([3]p.21)
 118     // TrackPoint might take 25ms ([5]2.7)
 119     uint8_t data = 0;
 120     uint8_t try = 200;
 121     while (try-- && (data = ps2_host_recv())) ;
 122     return data;
 123 }
 124
 125 /* send LED state to keyboard */
 126 void ps2_host_set_led(uint8_t led)
 127 {
 128     ps2_host_send(0xED);
 129     ps2_host_send(led);
 130 }
 131
 132
 133 /* called after start bit comes */
 134 uint8_t ps2_host_recv(void)
 135 {
 136     uint8_t data = 0;
 137     bool parity = true;
 138     ps2_error = PS2_ERR_NONE;
 139
 140     /* release lines(idle state) */
 141     idle();
 142
 143     /* start bit [1] */
 144     WAIT(clock_lo, 100, 1); // TODO: this is enough?
 145     WAIT(data_lo, 1, 2);
 146     WAIT(clock_hi, 50, 3);
 147
 148     /* data [2-9] */
 149     for (uint8_t i = 0; i < 8; i++) {
 150         WAIT(clock_lo, 50, 4);
 151         if (data_in()) {
 152             parity = !parity;
 153             data |= (1<<i);
 154         }
 155         WAIT(clock_hi, 50, 5);
 156     }
 157
 158     /* parity [10] */
 159     WAIT(clock_lo, 50, 6);
 160     if (data_in() != parity) {
 161         ps2_error = PS2_ERR_PARITY;
 162         goto ERROR;
 163     }
 164     WAIT(clock_hi, 50, 7);
 165
 166     /* stop bit [11] */
 167     WAIT(clock_lo, 50, 8);
 168     WAIT(data_hi, 1, 9);
 169     WAIT(clock_hi, 50, 10);
 170
 171     inhibit();
 172     return data;
 173 ERROR:
 174     if (ps2_error > PS2_ERR_STARTBIT3) {
 175         printf("x%02X\n", ps2_error);
 176     }
 177     inhibit();
 178     return 0;
 179 }