summaryrefslogtreecommitdiffstats
path: root/protocol/ps2.c
blob: 4c6c2fcb27b379b3e37b0f8e8adc5e66e237c5af (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
/*
Copyright 2010,2011 Jun WAKO <wakojun@gmail.com>

This software is licensed with a Modified BSD License.
All of this is supposed to be Free Software, Open Source, DFSG-free,
GPL-compatible, and OK to use in both free and proprietary applications.
Additions and corrections to this file are welcome.


Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in
  the documentation and/or other materials provided with the
  distribution.

* Neither the name of the copyright holders nor the names of
  contributors may be used to endorse or promote products derived
  from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/

#include <stdbool.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include "ps2.h"
#include "debug.h"


static uint8_t recv_data(void);
static inline void clock_lo(void);
static inline void clock_hi(void);
static inline bool clock_in(void);
static inline void data_lo(void);
static inline void data_hi(void);
static inline bool data_in(void);
static inline uint16_t wait_clock_lo(uint16_t us);
static inline uint16_t wait_clock_hi(uint16_t us);
static inline uint16_t wait_data_lo(uint16_t us);
static inline uint16_t wait_data_hi(uint16_t us);
static inline void idle(void);
static inline void inhibit(void);


/*
Primitive PS/2 Library for AVR
==============================
Host side is only supported now.


I/O control
-----------
High state is asserted by input with pull up.


PS/2 References
---------------
http://www.computer-engineering.org/ps2protocol/
http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
*/


#define WAIT(stat, us, err) do { \
    if (!wait_##stat(us)) { \
        ps2_error = err; \
        goto ERROR; \
    } \
} while (0)


uint8_t ps2_error = PS2_ERR_NONE;


void ps2_host_init(void)
{
#ifdef PS2_USE_INT
    PS2_INT_INIT();
    PS2_INT_ON();
    idle();
#else
    inhibit();
#endif
}

// TODO: send using interrupt if available
uint8_t ps2_host_send(uint8_t data)
{
    uint8_t res = 0;
    bool parity = true;
    ps2_error = PS2_ERR_NONE;
#ifdef PS2_USE_INT
    PS2_INT_OFF();
#endif
    /* terminate a transmission if we have */
    inhibit();
    _delay_us(200); // at least 100us

    /* start bit [1] */
    data_lo();
    clock_hi();
    WAIT(clock_lo, 20000, 10);   // may take 15ms at most until device starts clocking
    /* data [2-9] */
    for (uint8_t i = 0; i < 8; i++) {
        _delay_us(15);
        if (data&(1<<i)) {
            parity = !parity;
            data_hi();
        } else {
            data_lo();
        }
        WAIT(clock_hi, 50, 2);
        WAIT(clock_lo, 50, 3);
    }
    /* parity [10] */
    _delay_us(15);
    if (parity) { data_hi(); } else { data_lo(); }
    WAIT(clock_hi, 50, 4);
    WAIT(clock_lo, 50, 5);
    /* stop bit [11] */
    _delay_us(15);
    data_hi();
    /* ack [12] */
    WAIT(data_lo, 50, 6);
    WAIT(clock_lo, 50, 7);

    /* wait for idle state */
    WAIT(clock_hi, 50, 8);
    WAIT(data_hi, 50, 9);

    res = ps2_host_recv_response();
ERROR:
#ifdef PS2_USE_INT
    PS2_INT_ON();
    idle();
#else
    inhibit();
#endif
    return res;
}

/* receive data when host want else inhibit communication */
uint8_t ps2_host_recv_response(void)
{
    uint8_t data = 0;

    /* terminate a transmission if we have */
    inhibit();
    _delay_us(100);

    /* release lines(idle state) */
    idle();

    /* wait start bit */
    wait_clock_lo(25000);    // command response may take 20 ms at most
    data = recv_data();

    inhibit();
    return data;
}

#ifndef PS2_USE_INT
uint8_t ps2_host_recv(void)
{
    return ps2_host_recv_response();
}
#else
/* ring buffer to store ps/2 key data */
#define PBUF_SIZE 32
static uint8_t pbuf[PBUF_SIZE];
static uint8_t pbuf_head = 0;
static uint8_t pbuf_tail = 0;
static inline void pbuf_enqueue(uint8_t data)
{
    if (!data)
        return;

    uint8_t sreg = SREG;
    cli();
    uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
    if (next != pbuf_tail) {
        pbuf[pbuf_head] = data;
        pbuf_head = next;
    } else {
        debug("pbuf: full\n");
    }
    SREG = sreg;
}
static inline uint8_t pbuf_dequeue(void)
{
    uint8_t val = 0;

    uint8_t sreg = SREG;
    cli();
    if (pbuf_head != pbuf_tail) {
        val = pbuf[pbuf_tail];
        pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
    }
    SREG = sreg;

    return val;
}

/* get data received by interrupt */
uint8_t ps2_host_recv(void)
{
    if (ps2_error) {
        print("x");
        phex(ps2_error);
        ps2_host_send(0xFE);    // request to resend
        ps2_error = PS2_ERR_NONE;
    }
    idle();
    return pbuf_dequeue();
}

#if 0
#define DEBUGP_INIT() do { DDRC = 0xFF; } while (0)
#define DEBUGP(x) do { PORTC = x; } while (0)
#else
#define DEBUGP_INIT()
#define DEBUGP(x)
#endif
ISR(PS2_INT_VECT)
{
    static enum {
        INIT,
        START,
        BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7,
        PARITY,
        STOP,
    } state = INIT;
    static uint8_t data = 0;
    static uint8_t parity = 1;

    // TODO: abort if elapse 100us from previous interrupt

    // return unless falling edge
    if (clock_in()) {
        goto RETURN;
    }

    state++;
    DEBUGP(state);
    switch (state) {
        case START:
            if (data_in())
                goto ERROR;
            break;
        case BIT0:
        case BIT1:
        case BIT2:
        case BIT3:
        case BIT4:
        case BIT5:
        case BIT6:
        case BIT7:
            data >>= 1;
            if (data_in()) {
                data |= 0x80;
                parity++;
            }
            break;
        case PARITY:
            if (data_in()) {
                if (!(parity & 0x01))
                    goto ERROR;
            } else {
                if (parity & 0x01)
                    goto ERROR;
            }
            break;
        case STOP:
            if (!data_in())
                goto ERROR;
            pbuf_enqueue(data);
            goto DONE;
            break;
        default:
            goto ERROR;
    }
    goto RETURN;
ERROR:
    DEBUGP(0x0F);
    inhibit();
    ps2_error = state;
DONE:
    state = INIT;
    data = 0;
    parity = 1;
RETURN:
    return;
}
#endif


static void ps2_reset(void)
{
    ps2_host_send(0xFF);
}

/* send LED state to keyboard */
void ps2_host_set_led(uint8_t led)
{
    ps2_host_send(0xED);
    ps2_host_send(led);
}


/* called after start bit comes */
static uint8_t recv_data(void)
{
    uint8_t data = 0;
    bool parity = true;
    ps2_error = PS2_ERR_NONE;

    /* start bit [1] */
    WAIT(clock_lo, 1, 1);
    WAIT(data_lo, 1, 2);
    WAIT(clock_hi, 50, 3);

    /* data [2-9] */
    for (uint8_t i = 0; i < 8; i++) {
        WAIT(clock_lo, 50, 4);
        if (data_in()) {
            parity = !parity;
            data |= (1<<i);
        }
        WAIT(clock_hi, 50, 5);
    }

    /* parity [10] */
    WAIT(clock_lo, 50, 6);
    if (data_in() != parity) {
        ps2_error = PS2_ERR_PARITY;
        goto ERROR;
    }
    WAIT(clock_hi, 50, 7);

    /* stop bit [11] */
    WAIT(clock_lo, 50, 8);
    WAIT(data_hi, 1, 9);
    WAIT(clock_hi, 50, 10);

    return data;
ERROR:
    return 0;
}

static inline void clock_lo()
{
    PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
    PS2_CLOCK_DDR  |=  (1<<PS2_CLOCK_BIT);
}
static inline void clock_hi()
{
    /* input with pull up */
    PS2_CLOCK_DDR  &= ~(1<<PS2_CLOCK_BIT);
    PS2_CLOCK_PORT |=  (1<<PS2_CLOCK_BIT);
}
static inline bool clock_in()
{
    PS2_CLOCK_DDR  &= ~(1<<PS2_CLOCK_BIT);
    PS2_CLOCK_PORT |=  (1<<PS2_CLOCK_BIT);
    _delay_us(1);
    return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT);
}
static inline void data_lo()
{
    PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
    PS2_DATA_DDR  |=  (1<<PS2_DATA_BIT);
}
static inline void data_hi()
{
    /* input with pull up */
    PS2_DATA_DDR  &= ~(1<<PS2_DATA_BIT);
    PS2_DATA_PORT |=  (1<<PS2_DATA_BIT);
}
static inline bool data_in()
{
    PS2_DATA_DDR  &= ~(1<<PS2_DATA_BIT);
    PS2_DATA_PORT |=  (1<<PS2_DATA_BIT);
    _delay_us(1);
    return PS2_DATA_PIN&(1<<PS2_DATA_BIT);
}

static inline uint16_t wait_clock_lo(uint16_t us)
{
    while (clock_in()  && us) { asm(""); _delay_us(1); us--; }
    return us;
}
static inline uint16_t wait_clock_hi(uint16_t us)
{
    while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
    return us;
}
static inline uint16_t wait_data_lo(uint16_t us)
{
    while (data_in() && us)  { asm(""); _delay_us(1); us--; }
    return us;
}
static inline uint16_t wait_data_hi(uint16_t us)
{
    while (!data_in() && us)  { asm(""); _delay_us(1); us--; }
    return us;
}

/* idle state that device can send */
static inline void idle(void)
{
    clock_hi();
    data_hi();
}

/* inhibit device to send */
static inline void inhibit(void)
{
    clock_lo();
    data_hi();
}