protocol/ps2_usart.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 USART version
  40  */
  41
  42 #include <stdbool.h>
  43 #include <avr/io.h>
  44 #include <avr/interrupt.h>
  45 #include <util/delay.h>
  46 #include "ps2.h"
  47 #include "debug.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(); // without this many USART errors occur when cable is disconnected
  70     PS2_USART_INIT();
  71     PS2_USART_RX_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_USART_OFF();
  82
  83     /* terminate a transmission if we have */
  84     inhibit();
  85     _delay_us(100);
  86
  87     /* start bit [1] */
  88     data_lo();
  89     clock_hi();
  90     WAIT(clock_lo, 15000, 1);
  91     /* data [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     /* parity [10] */
 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     /* stop bit [11] */
 109     _delay_us(15);
 110     data_hi();
 111     /* ack [12] */
 112     WAIT(data_lo, 50, 6);
 113     WAIT(clock_lo, 50, 7);
 114
 115     /* wait for idle state */
 116     WAIT(clock_hi, 50, 8);
 117     WAIT(data_hi, 50, 9);
 118
 119     idle();
 120     PS2_USART_INIT();
 121     PS2_USART_RX_INT_ON();
 122     return ps2_host_recv_response();
 123 ERROR:
 124     idle();
 125     PS2_USART_INIT();
 126     PS2_USART_RX_INT_ON();
 127     return 0;
 128 }
 129
 130 // Do polling data from keyboard to get response to last command.
 131 uint8_t ps2_host_recv_response(void)
 132 {
 133     uint8_t retry = 25;
 134     while (retry-- && !pbuf_has_data()) {
 135         _delay_ms(1);   // without this delay it seems to fall into deadlock
 136     }
 137     return pbuf_dequeue();
 138 }
 139
 140 uint8_t ps2_host_recv(void)
 141 {
 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_USART_RX_VECT)
 152 {
 153     // TODO: request RESEND when error occurs?
 154     uint8_t error = PS2_USART_ERROR;    // USART error should be read before data
 155     uint8_t data = PS2_USART_RX_DATA;
 156     if (!error) {
 157         pbuf_enqueue(data);
 158     } else {
 159         xprintf("PS2 USART error: %02X data: %02X\n", error, data);
 160     }
 161 }
 162
 163 /* send LED state to keyboard */
 164 void ps2_host_set_led(uint8_t led)
 165 {
 166     ps2_host_send(0xED);
 167     ps2_host_send(led);
 168 }
 169
 170
 171 /*--------------------------------------------------------------------
 172  * Ring buffer to store scan codes from keyboard
 173  *------------------------------------------------------------------*/
 174 #define PBUF_SIZE 32
 175 static uint8_t pbuf[PBUF_SIZE];
 176 static uint8_t pbuf_head = 0;
 177 static uint8_t pbuf_tail = 0;
 178 static inline void pbuf_enqueue(uint8_t data)
 179 {
 180     uint8_t sreg = SREG;
 181     cli();
 182     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 183     if (next != pbuf_tail) {
 184         pbuf[pbuf_head] = data;
 185         pbuf_head = next;
 186     } else {
 187         debug("pbuf: full\n");
 188     }
 189     SREG = sreg;
 190 }
 191
 192 static inline uint8_t pbuf_dequeue(void)
 193 {
 194     uint8_t val = 0;
 195
 196     uint8_t sreg = SREG;
 197     cli();
 198     if (pbuf_head != pbuf_tail) {
 199         val = pbuf[pbuf_tail];
 200         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 201     }
 202     SREG = sreg;
 203
 204     return val;
 205 }
 206 static inline bool pbuf_has_data(void)
 207 {
 208     uint8_t sreg = SREG;
 209     cli();
 210     bool has_data = (pbuf_head != pbuf_tail);
 211     SREG = sreg;
 212     return has_data;
 213 }
 214 static inline void pbuf_clear(void)
 215 {
 216     uint8_t sreg = SREG;
 217     cli();
 218     pbuf_head = pbuf_tail = 0;
 219     SREG = sreg;
 220 }