ps2_usb/ps2_usart.c

   1 /*
   2 Copyright (c) 2010,2011 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 Primitive PS/2 Library for AVR
  39 ==============================
  40 Host side is only supported now.
  41 Synchronous USART is used to receive data by hardware process
  42 rather than interrupt. During V-USB interrupt runs, CLOCK interrupt
  43 cannot interpose. In the result it is prone to lost CLOCK edge.
  44
  45
  46 I/O control
  47 -----------
  48 High state is asserted by internal pull-up.
  49 If you have a signaling problem, you may need to have
  50 external pull-up resisters on CLOCK and DATA line.
  51
  52
  53 PS/2 References
  54 ---------------
  55 http://www.computer-engineering.org/ps2protocol/
  56 http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
  57 */
  58 #include <stdbool.h>
  59 #include <avr/io.h>
  60 #include <avr/interrupt.h>
  61 #include <util/delay.h>
  62 #include "ps2.h"
  63 #include "debug.h"
  64
  65
  66 #if 0
  67 #define DEBUGP_INIT() do { DDRC = 0xFF; } while (0)
  68 #define DEBUGP(x) do { PORTC = x; } while (0)
  69 #else
  70 #define DEBUGP_INIT()
  71 #define DEBUGP(x)
  72 #endif
  73
  74 #define WAIT(stat, us, err) do { \
  75     if (!wait_##stat(us)) { \
  76         ps2_error = err; \
  77         goto ERROR; \
  78     } \
  79 } while (0)
  80
  81
  82 uint8_t ps2_error = PS2_ERR_NONE;
  83
  84
  85 static inline void clock_lo(void);
  86 static inline void clock_hi(void);
  87 static inline bool clock_in(void);
  88 static inline void data_lo(void);
  89 static inline void data_hi(void);
  90 static inline bool data_in(void);
  91 static inline uint16_t wait_clock_lo(uint16_t us);
  92 static inline uint16_t wait_clock_hi(uint16_t us);
  93 static inline uint16_t wait_data_lo(uint16_t us);
  94 static inline uint16_t wait_data_hi(uint16_t us);
  95 static inline void idle(void);
  96 static inline void inhibit(void);
  97 #if defined PS2_USE_INT || defined PS2_USE_USART
  98 static inline uint8_t pbuf_dequeue(void);
  99 static inline void pbuf_enqueue(uint8_t data);
 100 #endif
 101
 102
 103 void ps2_host_init(void)
 104 {
 105     DEBUGP_INIT();
 106     DEBUGP(0x1);
 107     idle();
 108     PS2_USART_INIT();
 109     PS2_USART_RX_INT_ON();
 110 }
 111
 112 uint8_t ps2_host_send(uint8_t data)
 113 {
 114     uint8_t res = 0;
 115     bool parity = true;
 116     ps2_error = PS2_ERR_NONE;
 117
 118     DEBUGP(0x6);
 119     PS2_USART_OFF();
 120
 121     /* terminate a transmission if we have */
 122     inhibit();
 123     _delay_us(100);
 124
 125     /* start bit [1] */
 126     data_lo();
 127     clock_hi();
 128     WAIT(clock_lo, 15000, 1);
 129     /* data [2-9] */
 130     for (uint8_t i = 0; i < 8; i++) {
 131         _delay_us(15);
 132         if (data&(1<<i)) {
 133             parity = !parity;
 134             data_hi();
 135         } else {
 136             data_lo();
 137         }
 138         WAIT(clock_hi, 50, 2);
 139         WAIT(clock_lo, 50, 3);
 140     }
 141     /* parity [10] */
 142     _delay_us(15);
 143     if (parity) { data_hi(); } else { data_lo(); }
 144     WAIT(clock_hi, 50, 4);
 145     WAIT(clock_lo, 50, 5);
 146     /* stop bit [11] */
 147     _delay_us(15);
 148     data_hi();
 149     /* ack [12] */
 150     WAIT(data_lo, 50, 6);
 151     WAIT(clock_lo, 50, 7);
 152
 153     /* wait for idle state */
 154     WAIT(clock_hi, 50, 8);
 155     WAIT(data_hi, 50, 9);
 156
 157     res = ps2_host_recv_response();
 158 ERROR:
 159     idle();
 160     PS2_USART_INIT();
 161     PS2_USART_RX_INT_ON();
 162     return res;
 163 }
 164
 165 // Do polling data from keyboard to get response to last command.
 166 uint8_t ps2_host_recv_response(void)
 167 {
 168     uint8_t data = 0;
 169     PS2_USART_INIT();
 170     PS2_USART_RX_POLL_ON();
 171     while (!PS2_USART_RX_READY)
 172         ;
 173     data = PS2_USART_RX_DATA;
 174     PS2_USART_OFF();
 175     DEBUGP(0x9);
 176     return data;
 177 }
 178
 179 uint8_t ps2_host_recv(void)
 180 {
 181     return pbuf_dequeue();
 182 }
 183
 184 ISR(PS2_USART_RX_VECT)
 185 {
 186     DEBUGP(0x7);
 187     uint8_t error = PS2_USART_ERROR;
 188     uint8_t data = PS2_USART_RX_DATA;
 189     if (error) {
 190         DEBUGP(error>>2);
 191     } else {
 192         pbuf_enqueue(data);
 193     }
 194     DEBUGP(0x8);
 195 }
 196
 197 /* send LED state to keyboard */
 198 void ps2_host_set_led(uint8_t led)
 199 {
 200     // send 0xED then keyboard keeps waiting for next LED data
 201     // and keyboard does not send any scan codes during waiting.
 202     // If fail to send LED data keyboard looks like being freezed.
 203     uint8_t retry = 3;
 204     while (retry-- && ps2_host_send(PS2_SET_LED) != PS2_ACK)
 205         ;
 206     retry = 3;
 207     while (retry-- && ps2_host_send(led) != PS2_ACK)
 208         ;
 209 }
 210
 211
 212 /*--------------------------------------------------------------------
 213  * static functions
 214  *------------------------------------------------------------------*/
 215 static inline void clock_lo()
 216 {
 217     PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
 218     PS2_CLOCK_DDR  |=  (1<<PS2_CLOCK_BIT);
 219 }
 220 static inline void clock_hi()
 221 {
 222     /* input with pull up */
 223     PS2_CLOCK_DDR  &= ~(1<<PS2_CLOCK_BIT);
 224     PS2_CLOCK_PORT |=  (1<<PS2_CLOCK_BIT);
 225 }
 226 static inline bool clock_in()
 227 {
 228     PS2_CLOCK_DDR  &= ~(1<<PS2_CLOCK_BIT);
 229     PS2_CLOCK_PORT |=  (1<<PS2_CLOCK_BIT);
 230     _delay_us(1);
 231     return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT);
 232 }
 233 static inline void data_lo()
 234 {
 235     PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
 236     PS2_DATA_DDR  |=  (1<<PS2_DATA_BIT);
 237 }
 238 static inline void data_hi()
 239 {
 240     /* input with pull up */
 241     PS2_DATA_DDR  &= ~(1<<PS2_DATA_BIT);
 242     PS2_DATA_PORT |=  (1<<PS2_DATA_BIT);
 243 }
 244 static inline bool data_in()
 245 {
 246     PS2_DATA_DDR  &= ~(1<<PS2_DATA_BIT);
 247     PS2_DATA_PORT |=  (1<<PS2_DATA_BIT);
 248     _delay_us(1);
 249     return PS2_DATA_PIN&(1<<PS2_DATA_BIT);
 250 }
 251
 252 static inline uint16_t wait_clock_lo(uint16_t us)
 253 {
 254     while (clock_in()  && us) { asm(""); _delay_us(1); us--; }
 255     return us;
 256 }
 257 static inline uint16_t wait_clock_hi(uint16_t us)
 258 {
 259     while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
 260     return us;
 261 }
 262 static inline uint16_t wait_data_lo(uint16_t us)
 263 {
 264     while (data_in() && us)  { asm(""); _delay_us(1); us--; }
 265     return us;
 266 }
 267 static inline uint16_t wait_data_hi(uint16_t us)
 268 {
 269     while (!data_in() && us)  { asm(""); _delay_us(1); us--; }
 270     return us;
 271 }
 272
 273 /* idle state that device can send */
 274 static inline void idle(void)
 275 {
 276     clock_hi();
 277     data_hi();
 278 }
 279
 280 /* inhibit device to send */
 281 static inline void inhibit(void)
 282 {
 283     clock_lo();
 284     data_hi();
 285 }
 286
 287
 288 /*--------------------------------------------------------------------
 289  * Ring buffer to store scan codes from keyboard
 290  *------------------------------------------------------------------*/
 291 #define PBUF_SIZE 8
 292 static uint8_t pbuf[PBUF_SIZE];
 293 static uint8_t pbuf_head = 0;
 294 static uint8_t pbuf_tail = 0;
 295 static inline void pbuf_enqueue(uint8_t data)
 296 {
 297     if (!data)
 298         return;
 299
 300     uint8_t sreg = SREG;
 301     cli();
 302     uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
 303     if (next != pbuf_tail) {
 304         pbuf[pbuf_head] = data;
 305         pbuf_head = next;
 306     } else {
 307         debug("pbuf: full\n");
 308     }
 309     SREG = sreg;
 310 }
 311
 312 static inline uint8_t pbuf_dequeue(void)
 313 {
 314     uint8_t val = 0;
 315
 316     uint8_t sreg = SREG;
 317     cli();
 318     if (pbuf_head != pbuf_tail) {
 319         val = pbuf[pbuf_tail];
 320         pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
 321     }
 322     SREG = sreg;
 323
 324     return val;
 325 }