tmk_core/protocol/ps2_interrupt.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 /*
  39  * PS/2 protocol Pin interrupt version
  40  */
  41
  42 #include <stdbool.h>
  43 #include <avr/interrupt.h>
  44 #include <util/delay.h>
  45 #include "ps2.h"
  46 #include "ps2_io.h"
  47 #include "print.h"
  48
  49 #define WAIT(stat, us, err)     \
  50     do {                        \
  51         if (!wait_##stat(us)) { \
  52             ps2_error = err;    \
  53             goto ERROR;         \
  54         }                       \
  55     } while (0)
  56
  57 uint8_t ps2_error = PS2_ERR_NONE;
  58
  59 static inline uint8_t pbuf_dequeue(void);
  60 static inline void    pbuf_enqueue(uint8_t data);
  61 static inline bool    pbuf_has_data(void);
  62 static inline void    pbuf_clear(void);
  63
  64 void ps2_host_init(void) {
  65     idle();
  66     PS2_INT_INIT();
  67     PS2_INT_ON();
  68     // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
  69     //_delay_ms(2500);
  70 }
  71
  72 uint8_t ps2_host_send(uint8_t data) {
  73     bool parity = true;
  74     ps2_error   = PS2_ERR_NONE;
  75
  76     PS2_INT_OFF();
  77
  78     /* terminate a transmission if we have */
  79     inhibit();
  80     _delay_us(100);  // 100us [4]p.13, [5]p.50
  81
  82     /* 'Request to Send' and Start bit */
  83     data_lo();
  84     clock_hi();
  85     WAIT(clock_lo, 10000, 10);  // 10ms [5]p.50
  86
  87     /* Data bit[2-9] */
  88     for (uint8_t i = 0; i < 8; i++) {
  89         _delay_us(15);
  90         if (data & (1 << i)) {
  91             parity = !parity;
  92             data_hi();
  93         } else {
  94             data_lo();
  95         }
  96         WAIT(clock_hi, 50, 2);
  97         WAIT(clock_lo, 50, 3);
  98     }
  99
 100     /* Parity bit */
 101     _delay_us(15);
 102     if (parity) {
 103         data_hi();
 104     } else {
 105         data_lo();
 106     }
 107     WAIT(clock_hi, 50, 4);
 108     WAIT(clock_lo, 50, 5);
 109
 110     /* Stop bit */
 111     _delay_us(15);
 112     data_hi();
 113
 114     /* Ack */
 115     WAIT(data_lo, 50, 6);
 116     WAIT(clock_lo, 50, 7);
 117
 118     /* wait for idle state */
 119     WAIT(clock_hi, 50, 8);
 120     WAIT(data_hi, 50, 9);
 121
 122     idle();
 123     PS2_INT_ON();
 124     return ps2_host_recv_response();
 125 ERROR:
 126     idle();
 127     PS2_INT_ON();
 128     return 0;
 129 }
 130
 131 uint8_t ps2_host_recv_response(void) {
 132     // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
 133     uint8_t retry = 25;
 134     while (retry-- && !pbuf_has_data()) {
 135         _delay_ms(1);
 136     }
 137     return pbuf_dequeue();
 138 }
 139
 140 /* get data received by interrupt */
 141 uint8_t ps2_host_recv(void) {
 142     if (pbuf_has_data()) {
 143         ps2_error = PS2_ERR_NONE;
 144         return pbuf_dequeue();
 145     } else {
 146         ps2_error = PS2_ERR_NODATA;
 147         return 0;
 148     }
 149 }
 150
 151 ISR(PS2_INT_VECT) {
 152     static enum {
 153         INIT,
 154         START,
 155         BIT0,
 156         BIT1,
 157         BIT2,
 158         BIT3,
 159         BIT4,
 160         BIT5,
 161         BIT6,
 162         BIT7,
 163         PARITY,
 164         STOP,
 165     } state               = INIT;
 166     static uint8_t data   = 0;
 167     static uint8_t parity = 1;
 168
 169     // TODO: abort if elapse 100us from previous interrupt
 170
 171     // return unless falling edge
 172     if (clock_in()) {
 173         goto RETURN;
 174     }
 175
 176     state++;
 177     switch (state) {
 178         case START:
 179             if (data_in()) goto ERROR;
 180             break;
 181         case BIT0:
 182         case BIT1:
 183         case BIT2:
 184         case BIT3:
 185         case BIT4:
 186         case BIT5:
 187         case BIT6:
 188         case BIT7:
 189             data >>= 1;
 190             if (data_in()) {
 191                 data |= 0x80;
 192                 parity++;
 193             }
 194             break;
 195         case PARITY:
 196             if (data_in()) {
 197                 if (!(parity & 0x01)) goto ERROR;
 198             } else {
 199                 if (parity & 0x01) goto ERROR;
 200             }
 201             break;
 202         case STOP:
 203             if (!data_in()) goto ERROR;
 204             pbuf_enqueue(data);
 205             goto DONE;
 206             break;
 207         default:
 208             goto ERROR;
 209     }
 210     goto RETURN;
 211 ERROR:
 212     ps2_error = state;
 213 DONE:
 214     state  = INIT;
 215     data   = 0;
 216     parity = 1;
 217 RETURN:
 218     return;
 219 }
 220
 221 /* send LED state to keyboard */
 222 void ps2_host_set_led(uint8_t led) {
 223     ps2_host_send(0xED);
 224     ps2_host_send(led);
 225 }
 226
 227 /*--------------------------------------------------------------------
 228  * Ring buffer to store scan codes from keyboard
 229  *------------------------------------------------------------------*/
 230 #define PBUF_SIZE 32
 231 static uint8_t     pbuf[PBUF_SIZE];
 232 static uint8_t     pbuf_head = 0;
 233 static uint8_t     pbuf_tail = 0;
 234 static inline void pbuf_enqueue(uint8_t data) {
 235     uint8_t sreg = SREG;
 236     cli();
 237     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 238     if (next != pbuf_tail) {
 239         pbuf[pbuf_head] = data;
 240         pbuf_head       = next;
 241     } else {
 242         print("pbuf: full\n");
 243     }
 244     SREG = sreg;
 245 }
 246 static inline uint8_t pbuf_dequeue(void) {
 247     uint8_t val = 0;
 248
 249     uint8_t sreg = SREG;
 250     cli();
 251     if (pbuf_head != pbuf_tail) {
 252         val       = pbuf[pbuf_tail];
 253         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 254     }
 255     SREG = sreg;
 256
 257     return val;
 258 }
 259 static inline bool pbuf_has_data(void) {
 260     uint8_t sreg = SREG;
 261     cli();
 262     bool has_data = (pbuf_head != pbuf_tail);
 263     SREG          = sreg;
 264     return has_data;
 265 }
 266 static inline void pbuf_clear(void) {
 267     uint8_t sreg = SREG;
 268     cli();
 269     pbuf_head = pbuf_tail = 0;
 270     SREG                  = sreg;
 271 }