-
Notifications
You must be signed in to change notification settings - Fork 1
/
twi.c
351 lines (292 loc) · 10.1 KB
/
twi.c
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
/* Copyright (C) 2014-2015 David Zanetti
*
* This file is part of libkakapo.
*
* libkakapo is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License.
*
* libkakapo is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with libkapapo.
*
* If not, see <http://www.gnu.org/licenses/>.
*/
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <stdlib.h>
#include <stdio.h>
#include "global.h"
#include <util/delay.h>
#include "errors.h"
#include "twi.h"
#include "usart.h"
#include "debug.h"
typedef struct {
TWI_t *hw; /* pointer to real hardware */
twi_rwmode_t rw; /* what mode we were last asked to start for */
uint16_t timeout_us; /* How many us to wait before giving up */
} twi_port_t;
twi_port_t *twi_ports[MAX_TWI_PORTS] = TWI_INIT_PORTS;
int twi_wait_busowner(TWI_t *hw, uint16_t t);
int twi_wait_rwif(TWI_t *hw, uint16_t t);
/* initalise a port */
int twi_init(twi_portname_t port, uint16_t speed, uint16_t timeout_us) {
uint32_t baud;
if (twi_ports[port] || port >= MAX_TWI_PORTS) {
k_err("no such port %d",port);
return -ENODEV;
}
twi_ports[port] = malloc(sizeof(twi_port_t));
/* reset the mode */
twi_ports[port]->rw = twi_mode_read; /* well, it'll do */
twi_ports[port]->timeout_us = timeout_us;
switch (port) {
#if defined(TWIC)
case twi_c:
twi_ports[port]->hw = &TWIC;
break;
#endif
#if defined(TWID)
case twi_d:
twi_ports[port]->hw = &TWID;
break;
#endif
#if defined(TWIE)
case twi_e:
twi_ports[port]->hw = &TWIE;
break;
#endif
#if defined(TWIF)
case twi_f:
twi_ports[port]->hw = &TWIF;
break;
#endif
}
/* calculate the TWI baud rate for the CPU frequency */
baud = ((uint32_t)F_CPU / (2000UL*(uint32_t)speed))-5;
k_debug("port %d: baud=%d, timeout=%d",port,(uint8_t)baud,timeout_us);
twi_ports[port]->hw->MASTER.BAUD = (uint8_t) baud;
/* enable it */
twi_ports[port]->hw->MASTER.CTRLA |= TWI_MASTER_ENABLE_bm;
#ifdef TWI_USE_TIMEOUT
twi_ports[port]->hw->MASTER.CTRLB |= TWI_MASTER_TIMEOUT_200US_gc;
#endif
/* force into idle */
twi_ports[port]->hw->MASTER.STATUS = TWI_MASTER_BUSSTATE_IDLE_gc;
return 0;
}
int twi_wait_busowner(TWI_t *hw, uint16_t t) {
while ((hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) != TWI_MASTER_BUSSTATE_IDLE_gc &&
(hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) != TWI_MASTER_BUSSTATE_OWNER_gc) {
t--;
if (t == 0) {
return -ETIME;
}
_delay_us(1);
}
return 0;
}
int twi_wait_rwif(TWI_t *hw, uint16_t t) {
while ((hw->MASTER.STATUS & (TWI_MASTER_WIF_bm | TWI_MASTER_RIF_bm)) == 0) {
t--;
if (t == 0) {
return -ETIME;
}
_delay_us(1);
}
return 0;
}
/* issue (repeated-)start for TWI master mode */
/* repeated start is just a side effect of calling this when already owning the bus */
int twi_start(twi_portname_t port, uint8_t addr, twi_rwmode_t rw) {
TWI_t *hw; /* save us typing the array out all the time */
/* check we're operating on a real port */
if (!twi_ports[port] || port >= MAX_TWI_PORTS) {
k_err("no such port %d",port);
return -ENODEV;
}
if (rw > twi_mode_read) {
k_err("invalid mode");
return -EINVAL;
}
hw = twi_ports[port]->hw;
/* start by acquiring the bus */
k_debug("wait for bus acquire",twi_ports[port]->timeout_us);
if (twi_wait_busowner(hw,twi_ports[port]->timeout_us)) {
k_err("timeout for bus acquire");
return -ETIME;
}
k_debug("hailing %02x",addr);
if (rw == twi_mode_read) {
hw->MASTER.ADDR = (addr << 1) | 0x1;
} else {
hw->MASTER.ADDR = (addr << 1);
}
if (twi_wait_rwif(hw,twi_ports[port]->timeout_us)) {
k_warn("no response at addr %02x",addr);
return -ENODEV;
}
k_debug("wif/rif set");
/* at this point, we need to check what the status is */
if ((hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) == TWI_MASTER_BUSSTATE_BUSY_gc) {
k_warn("lost bus during start");
/* we failed to acquire the bus for some reason, toss error */
return -EBUSY;
}
/* we got a NAK, then toss error. Note: this probably never gets hit */
if (hw->MASTER.STATUS & TWI_MASTER_RXACK_bm) {
k_warn("no response at addr %02x",addr);
/* issue a stop to release the bus */
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
return -EIO;
}
/* these cases are different because we should have gotten a byte
* from the device already, in which case RIF is set too */
switch (rw) {
case twi_mode_write:
if ((hw->MASTER.STATUS & TWI_MASTER_RXACK_bm) == 0) {
k_debug("device %02x responded",addr);
twi_ports[port]->rw = twi_mode_write;
return 0;
}
break;
case twi_mode_read:
if ((hw->MASTER.STATUS & TWI_MASTER_RXACK_bm) == 0 &&
hw->MASTER.STATUS & TWI_MASTER_RIF_bm) {
k_debug("device %02x responded",addr);
twi_ports[port]->rw = twi_mode_read;
return 0;
}
break;
default:
break;
}
k_err("protocol error, giving up");
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
return -EIO;
}
int twi_write(twi_portname_t port, void *buf, uint16_t len, twi_end_t endstate) {
TWI_t *hw; /* the HW pointer */
if (!twi_ports[port] || port >= MAX_TWI_PORTS) {
k_err("no such port %d",port);
return -ENODEV;
}
if (twi_ports[port]->rw != twi_mode_write) {
k_err("write called in read mode");
return -EINVAL;
}
hw = twi_ports[port]->hw;
/* at this point, we need to check what the status is */
if ((hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) != TWI_MASTER_BUSSTATE_OWNER_gc) {
k_err("lost bus before write started");
return -EIO;
}
/* write the data out to the endpoint */
while (len) {
/* write a byte of data to the bus, and wait for interrupt */
k_debug("out: %02x",*(uint8_t *)buf);
hw->MASTER.DATA = *(uint8_t *)buf;
buf++;
len--;
k_debug("wait for write complete");
if (twi_wait_rwif(hw,twi_ports[port]->timeout_us)) {
k_err("write timeout, releasing bus");
/* return the bus to others, regardless */
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
return -EIO;
}
if ((hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) == TWI_MASTER_BUSSTATE_BUSY_gc) {
/* give up, something else is trashing the bus */
k_err("bus became busy during write, giving up");
return -EIO;
}
if (hw->MASTER.STATUS & TWI_MASTER_RXACK_bm) {
/* we got a NAK, so in either case, we stop sending stuff */
k_debug("nak recieved");
/* if we were expecting to release bus, do so. */
/* we force release when bytes pending */
if (endstate == twi_stop || len) {
k_debug("releasing bus");
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
}
if (len) {
/* we had bytes left to send */
k_err("slave NAK while bytes pending");
return -EIO;
}
return 0; /* we had nothing left to send anyway, so we're fine */
}
if ((hw->MASTER.STATUS & TWI_MASTER_RXACK_bm) == 0) {
/* all good */
k_debug("ack received");
continue;
}
k_err("protocol error, giving up");
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
return -EIO;
}
k_debug("tx complete");
if (endstate == twi_stop) {
/* release the bus */
k_debug("releasing bus");
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
}
return 0;
}
int twi_read(twi_portname_t port, void *buf, uint16_t len, twi_end_t endstate) {
TWI_t *hw; /* the HW pointer */
if (!twi_ports[port] || port >= MAX_TWI_PORTS) {
k_err("no such port %d",port);
return -ENODEV;
}
if (twi_ports[port]->rw != twi_mode_read) {
k_err("read called in write mode");
return -EINVAL;
}
hw = twi_ports[port]->hw;
/* at this point, we need to check what the status is */
if ((hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) != TWI_MASTER_BUSSTATE_OWNER_gc) {
k_err("lost bus before write started");
return -EIO;
}
/* read the data as it comes in */
while (len) {
k_debug("waiting for next rx");
/* this will have RIF set on the first pass from twi_start() in read
* mode so should just immediately RX. Check WIF for bus errors */
if (twi_wait_rwif(hw,twi_ports[port]->timeout_us)) {
k_err("read timeout, releasing bus");
/* always release the bus */
hw->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
return -ETIME;
}
/* check for bus error */
if ((hw->MASTER.STATUS & TWI_MASTER_BUSSTATE_gm) == TWI_MASTER_BUSSTATE_BUSY_gc) {
/* give up, something else is trashing the bus */
k_err("bus became busy during read, giving up");
return -EIO;
}
/* do actual RX */
*(uint8_t *)buf = hw->MASTER.DATA;
k_debug("rx %02x",*(uint8_t *)buf);
buf++;
len--;
if (!len && endstate == twi_stop) {
k_debug("rx complete, send nak + releasing bus");
hw->MASTER.CTRLC = TWI_MASTER_ACKACT_bm | TWI_MASTER_CMD_STOP_gc;
break;
}
/* we may not be expecting any more reads at this point, but
* send the ack for now and well.. we'll just toss the byte */
k_debug("expect more, send ack");
hw->MASTER.CTRLC = TWI_MASTER_CMD_RECVTRANS_gc;
}
/* all done */
return 0;
}