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 <util/delay.h>
  44 #include "ps2.h"
  45 #include "debug.h"
  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
  56 uint8_t ps2_error = PS2_ERR_NONE;
  57
  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
  65 void ps2_host_init(void)
  66 {
  67     idle();
  68     PS2_INT_INIT();
  69     PS2_INT_ON();
  70     // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
  71     //_delay_ms(2500);
  72 }
  73
  74 uint8_t ps2_host_send(uint8_t data)
  75 {
  76     bool parity = true;
  77     ps2_error = PS2_ERR_NONE;
  78
  79     PS2_INT_OFF();
  80
  81     /* terminate a transmission if we have */
  82     inhibit();
  83     _delay_us(100); // 100us [4]p.13, [5]p.50
  84
  85     /* 'Request to Send' and Start bit */
  86     data_lo();
  87     clock_hi();
  88     WAIT(clock_lo, 10000, 10);   // 10ms [5]p.50
  89
  90     /* Data bit[2-9] */
  91     for (uint8_t i = 0; i < 8; i++) {
  92         _delay_us(15);
  93         if (data&(1<<i)) {
  94             parity = !parity;
  95             data_hi();
  96         } else {
  97             data_lo();
  98         }
  99         WAIT(clock_hi, 50, 2);
 100         WAIT(clock_lo, 50, 3);
 101     }
 102
 103     /* Parity bit */
 104     _delay_us(15);
 105     if (parity) { data_hi(); } else { data_lo(); }
 106     WAIT(clock_hi, 50, 4);
 107     WAIT(clock_lo, 50, 5);
 108
 109     /* Stop bit */
 110     _delay_us(15);
 111     data_hi();
 112
 113     /* Ack */
 114     WAIT(data_lo, 50, 6);
 115     WAIT(clock_lo, 50, 7);
 116
 117     /* wait for idle state */
 118     WAIT(clock_hi, 50, 8);
 119     WAIT(data_hi, 50, 9);
 120
 121     idle();
 122     PS2_INT_ON();
 123     return ps2_host_recv_response();
 124 ERROR:
 125     idle();
 126     PS2_INT_ON();
 127     return 0;
 128 }
 129
 130 uint8_t ps2_host_recv_response(void)
 131 {
 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 {
 143     if (pbuf_has_data()) {
 144         ps2_error = PS2_ERR_NONE;
 145         return pbuf_dequeue();
 146     } else {
 147         ps2_error = PS2_ERR_NODATA;
 148         return 0;
 149     }
 150 }
 151
 152 ISR(PS2_INT_VECT)
 153 {
 154     static enum {
 155         INIT,
 156         START,
 157         BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
 158         PARITY,
 159         STOP,
 160     } state = INIT;
 161     static uint8_t data = 0;
 162     static uint8_t parity = 1;
 163
 164     // TODO: abort if elapse 100us from previous interrupt
 165
 166     // return unless falling edge
 167     if (clock_in()) {
 168         goto RETURN;
 169     }
 170
 171     state++;
 172     switch (state) {
 173         case START:
 174             if (data_in())
 175                 goto ERROR;
 176             break;
 177         case BIT0:
 178         case BIT1:
 179         case BIT2:
 180         case BIT3:
 181         case BIT4:
 182         case BIT5:
 183         case BIT6:
 184         case BIT7:
 185             data >>= 1;
 186             if (data_in()) {
 187                 data |= 0x80;
 188                 parity++;
 189             }
 190             break;
 191         case PARITY:
 192             if (data_in()) {
 193                 if (!(parity & 0x01))
 194                     goto ERROR;
 195             } else {
 196                 if (parity & 0x01)
 197                     goto ERROR;
 198             }
 199             break;
 200         case STOP:
 201             if (!data_in())
 202                 goto ERROR;
 203             pbuf_enqueue(data);
 204             goto DONE;
 205             break;
 206         default:
 207             goto ERROR;
 208     }
 209     goto RETURN;
 210 ERROR:
 211     ps2_error = state;
 212 DONE:
 213     state = INIT;
 214     data = 0;
 215     parity = 1;
 216 RETURN:
 217     return;
 218 }
 219
 220 /* send LED state to keyboard */
 221 void ps2_host_set_led(uint8_t led)
 222 {
 223     ps2_host_send(0xED);
 224     ps2_host_send(led);
 225 }
 226
 227
 228 /*--------------------------------------------------------------------
 229  * Ring buffer to store scan codes from keyboard
 230  *------------------------------------------------------------------*/
 231 #define PBUF_SIZE 32
 232 static uint8_t pbuf[PBUF_SIZE];
 233 static uint8_t pbuf_head = 0;
 234 static uint8_t pbuf_tail = 0;
 235 static inline void pbuf_enqueue(uint8_t data)
 236 {
 237     uint8_t sreg = SREG;
 238     cli();
 239     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 240     if (next != pbuf_tail) {
 241         pbuf[pbuf_head] = data;
 242         pbuf_head = next;
 243     } else {
 244         debug("pbuf: full\n");
 245     }
 246     SREG = sreg;
 247 }
 248 static inline uint8_t pbuf_dequeue(void)
 249 {
 250     uint8_t val = 0;
 251
 252     uint8_t sreg = SREG;
 253     cli();
 254     if (pbuf_head != pbuf_tail) {
 255         val = pbuf[pbuf_tail];
 256         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 257     }
 258     SREG = sreg;
 259
 260     return val;
 261 }
 262 static inline bool pbuf_has_data(void)
 263 {
 264     uint8_t sreg = SREG;
 265     cli();
 266     bool has_data = (pbuf_head != pbuf_tail);
 267     SREG = sreg;
 268     return has_data;
 269 }
 270 static inline void pbuf_clear(void)
 271 {
 272     uint8_t sreg = SREG;
 273     cli();
 274     pbuf_head = pbuf_tail = 0;
 275     SREG = sreg;
 276 }
 277