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 "print.h"
  47
  48
  49 #define WAIT(stat, us, err) do { \
  50     if (!wait_##stat(us)) { \
  51         ps2_error = err; \
  52         goto ERROR; \
  53     } \
  54 } while (0)
  55
  56
  57 uint8_t ps2_error = PS2_ERR_NONE;
  58
  59
  60 static inline uint8_t pbuf_dequeue(void);
  61 static inline void pbuf_enqueue(uint8_t data);
  62 static inline bool pbuf_has_data(void);
  63 static inline void pbuf_clear(void);
  64
  65
  66 void ps2_host_init(void)
  67 {
  68     idle();
  69     PS2_INT_INIT();
  70     PS2_INT_ON();
  71     // POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
  72     //_delay_ms(2500);
  73 }
  74
  75 uint8_t ps2_host_send(uint8_t data)
  76 {
  77     bool parity = true;
  78     ps2_error = PS2_ERR_NONE;
  79
  80     PS2_INT_OFF();
  81
  82     /* terminate a transmission if we have */
  83     inhibit();
  84     _delay_us(100); // 100us [4]p.13, [5]p.50
  85
  86     /* 'Request to Send' and Start bit */
  87     data_lo();
  88     clock_hi();
  89     WAIT(clock_lo, 10000, 10);   // 10ms [5]p.50
  90
  91     /* Data bit[2-9] */
  92     for (uint8_t i = 0; i < 8; i++) {
  93         _delay_us(15);
  94         if (data&(1<<i)) {
  95             parity = !parity;
  96             data_hi();
  97         } else {
  98             data_lo();
  99         }
 100         WAIT(clock_hi, 50, 2);
 101         WAIT(clock_lo, 50, 3);
 102     }
 103
 104     /* Parity bit */
 105     _delay_us(15);
 106     if (parity) { data_hi(); } else { data_lo(); }
 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 {
 133     // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
 134     uint8_t retry = 25;
 135     while (retry-- && !pbuf_has_data()) {
 136         _delay_ms(1);
 137     }
 138     return pbuf_dequeue();
 139 }
 140
 141 /* get data received by interrupt */
 142 uint8_t ps2_host_recv(void)
 143 {
 144     if (pbuf_has_data()) {
 145         ps2_error = PS2_ERR_NONE;
 146         return pbuf_dequeue();
 147     } else {
 148         ps2_error = PS2_ERR_NODATA;
 149         return 0;
 150     }
 151 }
 152
 153 ISR(PS2_INT_VECT)
 154 {
 155     static enum {
 156         INIT,
 157         START,
 158         BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
 159         PARITY,
 160         STOP,
 161     } state = INIT;
 162     static uint8_t data = 0;
 163     static uint8_t parity = 1;
 164
 165     // TODO: abort if elapse 100us from previous interrupt
 166
 167     // return unless falling edge
 168     if (clock_in()) {
 169         goto RETURN;
 170     }
 171
 172     state++;
 173     switch (state) {
 174         case START:
 175             if (data_in())
 176                 goto ERROR;
 177             break;
 178         case BIT0:
 179         case BIT1:
 180         case BIT2:
 181         case BIT3:
 182         case BIT4:
 183         case BIT5:
 184         case BIT6:
 185         case BIT7:
 186             data >>= 1;
 187             if (data_in()) {
 188                 data |= 0x80;
 189                 parity++;
 190             }
 191             break;
 192         case PARITY:
 193             if (data_in()) {
 194                 if (!(parity & 0x01))
 195                     goto ERROR;
 196             } else {
 197                 if (parity & 0x01)
 198                     goto ERROR;
 199             }
 200             break;
 201         case STOP:
 202             if (!data_in())
 203                 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 {
 224     ps2_host_send(0xED);
 225     ps2_host_send(led);
 226 }
 227
 228
 229 /*--------------------------------------------------------------------
 230  * Ring buffer to store scan codes from keyboard
 231  *------------------------------------------------------------------*/
 232 #define PBUF_SIZE 32
 233 static uint8_t pbuf[PBUF_SIZE];
 234 static uint8_t pbuf_head = 0;
 235 static uint8_t pbuf_tail = 0;
 236 static inline void pbuf_enqueue(uint8_t data)
 237 {
 238     uint8_t sreg = SREG;
 239     cli();
 240     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 241     if (next != pbuf_tail) {
 242         pbuf[pbuf_head] = data;
 243         pbuf_head = next;
 244     } else {
 245         print("pbuf: full\n");
 246     }
 247     SREG = sreg;
 248 }
 249 static inline uint8_t pbuf_dequeue(void)
 250 {
 251     uint8_t val = 0;
 252
 253     uint8_t sreg = SREG;
 254     cli();
 255     if (pbuf_head != pbuf_tail) {
 256         val = pbuf[pbuf_tail];
 257         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 258     }
 259     SREG = sreg;
 260
 261     return val;
 262 }
 263 static inline bool pbuf_has_data(void)
 264 {
 265     uint8_t sreg = SREG;
 266     cli();
 267     bool has_data = (pbuf_head != pbuf_tail);
 268     SREG = sreg;
 269     return has_data;
 270 }
 271 static inline void pbuf_clear(void)
 272 {
 273     uint8_t sreg = SREG;
 274     cli();
 275     pbuf_head = pbuf_tail = 0;
 276     SREG = sreg;
 277 }
 278