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
  50 #define WAIT(stat, us, err) do { \
  51     if (!wait_##stat(us)) { \
  52         ps2_error = err; \
  53         goto ERROR; \
  54     } \
  55 } while (0)
  56
  57
  58 uint8_t ps2_error = PS2_ERR_NONE;
  59
  60
  61 static inline uint8_t pbuf_dequeue(void);
  62 static inline void pbuf_enqueue(uint8_t data);
  63 static inline bool pbuf_has_data(void);
  64 static inline void pbuf_clear(void);
  65
  66
  67 void ps2_host_init(void)
  68 {
  69     idle();
  70     PS2_INT_INIT();
  71     PS2_INT_ON();
  72     // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
  73     //_delay_ms(2500);
  74 }
  75
  76 uint8_t ps2_host_send(uint8_t data)
  77 {
  78     bool parity = true;
  79     ps2_error = PS2_ERR_NONE;
  80
  81     PS2_INT_OFF();
  82
  83     /* terminate a transmission if we have */
  84     inhibit();
  85     _delay_us(100); // 100us [4]p.13, [5]p.50
  86
  87     /* 'Request to Send' and Start bit */
  88     data_lo();
  89     clock_hi();
  90     WAIT(clock_lo, 10000, 10);   // 10ms [5]p.50
  91
  92     /* Data bit[2-9] */
  93     for (uint8_t i = 0; i < 8; i++) {
  94         _delay_us(15);
  95         if (data&(1<<i)) {
  96             parity = !parity;
  97             data_hi();
  98         } else {
  99             data_lo();
 100         }
 101         WAIT(clock_hi, 50, 2);
 102         WAIT(clock_lo, 50, 3);
 103     }
 104
 105     /* Parity bit */
 106     _delay_us(15);
 107     if (parity) { data_hi(); } else { data_lo(); }
 108     WAIT(clock_hi, 50, 4);
 109     WAIT(clock_lo, 50, 5);
 110
 111     /* Stop bit */
 112     _delay_us(15);
 113     data_hi();
 114
 115     /* Ack */
 116     WAIT(data_lo, 50, 6);
 117     WAIT(clock_lo, 50, 7);
 118
 119     /* wait for idle state */
 120     WAIT(clock_hi, 50, 8);
 121     WAIT(data_hi, 50, 9);
 122
 123     idle();
 124     PS2_INT_ON();
 125     return ps2_host_recv_response();
 126 ERROR:
 127     idle();
 128     PS2_INT_ON();
 129     return 0;
 130 }
 131
 132 uint8_t ps2_host_recv_response(void)
 133 {
 134     // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
 135     uint8_t retry = 25;
 136     while (retry-- && !pbuf_has_data()) {
 137         _delay_ms(1);
 138     }
 139     return pbuf_dequeue();
 140 }
 141
 142 /* get data received by interrupt */
 143 uint8_t ps2_host_recv(void)
 144 {
 145     if (pbuf_has_data()) {
 146         ps2_error = PS2_ERR_NONE;
 147         return pbuf_dequeue();
 148     } else {
 149         ps2_error = PS2_ERR_NODATA;
 150         return 0;
 151     }
 152 }
 153
 154 ISR(PS2_INT_VECT)
 155 {
 156     static enum {
 157         INIT,
 158         START,
 159         BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
 160         PARITY,
 161         STOP,
 162     } state = INIT;
 163     static uint8_t data = 0;
 164     static uint8_t parity = 1;
 165
 166     // TODO: abort if elapse 100us from previous interrupt
 167
 168     // return unless falling edge
 169     if (clock_in()) {
 170         goto RETURN;
 171     }
 172
 173     state++;
 174     switch (state) {
 175         case START:
 176             if (data_in())
 177                 goto ERROR;
 178             break;
 179         case BIT0:
 180         case BIT1:
 181         case BIT2:
 182         case BIT3:
 183         case BIT4:
 184         case BIT5:
 185         case BIT6:
 186         case BIT7:
 187             data >>= 1;
 188             if (data_in()) {
 189                 data |= 0x80;
 190                 parity++;
 191             }
 192             break;
 193         case PARITY:
 194             if (data_in()) {
 195                 if (!(parity & 0x01))
 196                     goto ERROR;
 197             } else {
 198                 if (parity & 0x01)
 199                     goto ERROR;
 200             }
 201             break;
 202         case STOP:
 203             if (!data_in())
 204                 goto ERROR;
 205             pbuf_enqueue(data);
 206             goto DONE;
 207             break;
 208         default:
 209             goto ERROR;
 210     }
 211     goto RETURN;
 212 ERROR:
 213     ps2_error = state;
 214 DONE:
 215     state = INIT;
 216     data = 0;
 217     parity = 1;
 218 RETURN:
 219     return;
 220 }
 221
 222 /* send LED state to keyboard */
 223 void ps2_host_set_led(uint8_t led)
 224 {
 225     ps2_host_send(0xED);
 226     ps2_host_send(led);
 227 }
 228
 229
 230 /*--------------------------------------------------------------------
 231  * Ring buffer to store scan codes from keyboard
 232  *------------------------------------------------------------------*/
 233 #define PBUF_SIZE 32
 234 static uint8_t pbuf[PBUF_SIZE];
 235 static uint8_t pbuf_head = 0;
 236 static uint8_t pbuf_tail = 0;
 237 static inline void pbuf_enqueue(uint8_t data)
 238 {
 239     uint8_t sreg = SREG;
 240     cli();
 241     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 242     if (next != pbuf_tail) {
 243         pbuf[pbuf_head] = data;
 244         pbuf_head = next;
 245     } else {
 246         print("pbuf: full\n");
 247     }
 248     SREG = sreg;
 249 }
 250 static inline uint8_t pbuf_dequeue(void)
 251 {
 252     uint8_t val = 0;
 253
 254     uint8_t sreg = SREG;
 255     cli();
 256     if (pbuf_head != pbuf_tail) {
 257         val = pbuf[pbuf_tail];
 258         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 259     }
 260     SREG = sreg;
 261
 262     return val;
 263 }
 264 static inline bool pbuf_has_data(void)
 265 {
 266     uint8_t sreg = SREG;
 267     cli();
 268     bool has_data = (pbuf_head != pbuf_tail);
 269     SREG = sreg;
 270     return has_data;
 271 }
 272 static inline void pbuf_clear(void)
 273 {
 274     uint8_t sreg = SREG;
 275     cli();
 276     pbuf_head = pbuf_tail = 0;
 277     SREG = sreg;
 278 }
 279