tmk_core/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/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();  // without this many USART errors occur when cable is disconnected
  66     PS2_USART_INIT();
  67     PS2_USART_RX_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_USART_OFF();
  77
  78     /* terminate a transmission if we have */
  79     inhibit();
  80     _delay_us(100);  // [4]p.13
  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_USART_INIT();
 124     PS2_USART_RX_INT_ON();
 125     return ps2_host_recv_response();
 126 ERROR:
 127     idle();
 128     PS2_USART_INIT();
 129     PS2_USART_RX_INT_ON();
 130     return 0;
 131 }
 132
 133 uint8_t ps2_host_recv_response(void) {
 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 uint8_t ps2_host_recv(void) {
 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_USART_RX_VECT) {
 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     ps2_host_send(0xED);
 166     ps2_host_send(led);
 167 }
 168
 169 /*--------------------------------------------------------------------
 170  * Ring buffer to store scan codes from keyboard
 171  *------------------------------------------------------------------*/
 172 #define PBUF_SIZE 32
 173 static uint8_t     pbuf[PBUF_SIZE];
 174 static uint8_t     pbuf_head = 0;
 175 static uint8_t     pbuf_tail = 0;
 176 static inline void pbuf_enqueue(uint8_t data) {
 177     uint8_t sreg = SREG;
 178     cli();
 179     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 180     if (next != pbuf_tail) {
 181         pbuf[pbuf_head] = data;
 182         pbuf_head       = next;
 183     } else {
 184         print("pbuf: full\n");
 185     }
 186     SREG = sreg;
 187 }
 188 static inline uint8_t pbuf_dequeue(void) {
 189     uint8_t val = 0;
 190
 191     uint8_t sreg = SREG;
 192     cli();
 193     if (pbuf_head != pbuf_tail) {
 194         val       = pbuf[pbuf_tail];
 195         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 196     }
 197     SREG = sreg;
 198
 199     return val;
 200 }
 201 static inline bool pbuf_has_data(void) {
 202     uint8_t sreg = SREG;
 203     cli();
 204     bool has_data = (pbuf_head != pbuf_tail);
 205     SREG          = sreg;
 206     return has_data;
 207 }
 208 static inline void pbuf_clear(void) {
 209     uint8_t sreg = SREG;
 210     cli();
 211     pbuf_head = pbuf_tail = 0;
 212     SREG                  = sreg;
 213 }