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1/*
2 * spi_butterfly.c - parport-to-butterfly adapter
3 *
4 * Copyright (C) 2005 David Brownell
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
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20#include <linux/kernel.h>
21#include <linux/init.h>
22#include <linux/delay.h>
da675296 23#include <linux/device.h>
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24#include <linux/parport.h>
25
914e2637 26#include <linux/sched.h>
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27#include <linux/spi/spi.h>
28#include <linux/spi/spi_bitbang.h>
29#include <linux/spi/flash.h>
30
31#include <linux/mtd/partitions.h>
32
33
34/*
35 * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
36 * with a battery powered AVR microcontroller and lots of goodies. You
37 * can use GCC to develop firmware for this.
38 *
39 * See Documentation/spi/butterfly for information about how to build
40 * and use this custom parallel port cable.
41 */
42
43#undef HAVE_USI /* nyet */
44
45
46/* DATA output bits (pins 2..9 == D0..D7) */
47#define butterfly_nreset (1 << 1) /* pin 3 */
48
49#define spi_sck_bit (1 << 0) /* pin 2 */
50#define spi_mosi_bit (1 << 7) /* pin 9 */
51
52#define usi_sck_bit (1 << 3) /* pin 5 */
53#define usi_mosi_bit (1 << 4) /* pin 6 */
54
55#define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */
56
57/* STATUS input bits */
58#define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */
59
60#define usi_miso_bit PARPORT_STATUS_PAPEROUT /* pin 12 */
61
62/* CONTROL output bits */
63#define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */
64/* USI uses no chipselect */
65
66
67
68static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
69{
70 return spi->controller_data;
71}
72
73static inline int is_usidev(struct spi_device *spi)
74{
75#ifdef HAVE_USI
76 return spi->chip_select != 1;
77#else
78 return 0;
79#endif
80}
81
82
83struct butterfly {
84 /* REVISIT ... for now, this must be first */
85 struct spi_bitbang bitbang;
86
87 struct parport *port;
88 struct pardevice *pd;
89
90 u8 lastbyte;
91
92 struct spi_device *dataflash;
93 struct spi_device *butterfly;
94 struct spi_board_info info[2];
95
96};
97
98/*----------------------------------------------------------------------*/
99
100/*
101 * these routines may be slower than necessary because they're hiding
102 * the fact that there are two different SPI busses on this cable: one
103 * to the DataFlash chip (or AVR SPI controller), the other to the
104 * AVR USI controller.
105 */
106
107static inline void
108setsck(struct spi_device *spi, int is_on)
109{
110 struct butterfly *pp = spidev_to_pp(spi);
111 u8 bit, byte = pp->lastbyte;
112
113 if (is_usidev(spi))
114 bit = usi_sck_bit;
115 else
116 bit = spi_sck_bit;
117
118 if (is_on)
119 byte |= bit;
120 else
121 byte &= ~bit;
122 parport_write_data(pp->port, byte);
123 pp->lastbyte = byte;
124}
125
126static inline void
127setmosi(struct spi_device *spi, int is_on)
128{
129 struct butterfly *pp = spidev_to_pp(spi);
130 u8 bit, byte = pp->lastbyte;
131
132 if (is_usidev(spi))
133 bit = usi_mosi_bit;
134 else
135 bit = spi_mosi_bit;
136
137 if (is_on)
138 byte |= bit;
139 else
140 byte &= ~bit;
141 parport_write_data(pp->port, byte);
142 pp->lastbyte = byte;
143}
144
145static inline int getmiso(struct spi_device *spi)
146{
147 struct butterfly *pp = spidev_to_pp(spi);
148 int value;
149 u8 bit;
150
151 if (is_usidev(spi))
152 bit = usi_miso_bit;
153 else
154 bit = spi_miso_bit;
155
156 /* only STATUS_BUSY is NOT negated */
157 value = !(parport_read_status(pp->port) & bit);
158 return (bit == PARPORT_STATUS_BUSY) ? value : !value;
159}
160
161static void butterfly_chipselect(struct spi_device *spi, int value)
162{
163 struct butterfly *pp = spidev_to_pp(spi);
164
165 /* set default clock polarity */
9c1da3cb 166 if (value != BITBANG_CS_INACTIVE)
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167 setsck(spi, spi->mode & SPI_CPOL);
168
169 /* no chipselect on this USI link config */
170 if (is_usidev(spi))
171 return;
172
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173 /* here, value == "activate or not";
174 * most PARPORT_CONTROL_* bits are negated, so we must
175 * morph it to value == "bit value to write in control register"
176 */
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177 if (spi_cs_bit == PARPORT_CONTROL_INIT)
178 value = !value;
179
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180 parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
181}
182
183
184/* we only needed to implement one mode here, and choose SPI_MODE_0 */
185
186#define spidelay(X) do{}while(0)
187//#define spidelay ndelay
188
189#define EXPAND_BITBANG_TXRX
190#include <linux/spi/spi_bitbang.h>
191
192static u32
193butterfly_txrx_word_mode0(struct spi_device *spi,
194 unsigned nsecs,
195 u32 word, u8 bits)
196{
197 return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
198}
199
200/*----------------------------------------------------------------------*/
201
202/* override default partitioning with cmdlinepart */
203static struct mtd_partition partitions[] = { {
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204 /* JFFS2 wants partitions of 4*N blocks for this device,
205 * so sectors 0 and 1 can't be partitions by themselves.
206 */
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207
208 /* sector 0 = 8 pages * 264 bytes/page (1 block)
209 * sector 1 = 248 pages * 264 bytes/page
210 */
211 .name = "bookkeeping", // 66 KB
212 .offset = 0,
213 .size = (8 + 248) * 264,
214// .mask_flags = MTD_WRITEABLE,
215}, {
216 /* sector 2 = 256 pages * 264 bytes/page
217 * sectors 3-5 = 512 pages * 264 bytes/page
218 */
219 .name = "filesystem", // 462 KB
220 .offset = MTDPART_OFS_APPEND,
221 .size = MTDPART_SIZ_FULL,
222} };
223
224static struct flash_platform_data flash = {
225 .name = "butterflash",
226 .parts = partitions,
227 .nr_parts = ARRAY_SIZE(partitions),
228};
229
230
231/* REVISIT remove this ugly global and its "only one" limitation */
232static struct butterfly *butterfly;
233
234static void butterfly_attach(struct parport *p)
235{
236 struct pardevice *pd;
237 int status;
238 struct butterfly *pp;
239 struct spi_master *master;
da675296 240 struct device *dev = p->physport->dev;
2e10c84b 241
da675296 242 if (butterfly || !dev)
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243 return;
244
245 /* REVISIT: this just _assumes_ a butterfly is there ... no probe,
246 * and no way to be selective about what it binds to.
247 */
248
da675296 249 master = spi_alloc_master(dev, sizeof *pp);
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250 if (!master) {
251 status = -ENOMEM;
252 goto done;
253 }
254 pp = spi_master_get_devdata(master);
255
256 /*
257 * SPI and bitbang hookup
258 *
259 * use default setup(), cleanup(), and transfer() methods; and
260 * only bother implementing mode 0. Start it later.
261 */
262 master->bus_num = 42;
263 master->num_chipselect = 2;
264
265 pp->bitbang.master = spi_master_get(master);
266 pp->bitbang.chipselect = butterfly_chipselect;
267 pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
268
269 /*
270 * parport hookup
271 */
272 pp->port = p;
273 pd = parport_register_device(p, "spi_butterfly",
274 NULL, NULL, NULL,
275 0 /* FLAGS */, pp);
276 if (!pd) {
277 status = -ENOMEM;
278 goto clean0;
279 }
280 pp->pd = pd;
281
282 status = parport_claim(pd);
283 if (status < 0)
284 goto clean1;
285
286 /*
287 * Butterfly reset, powerup, run firmware
288 */
289 pr_debug("%s: powerup/reset Butterfly\n", p->name);
290
291 /* nCS for dataflash (this bit is inverted on output) */
292 parport_frob_control(pp->port, spi_cs_bit, 0);
293
294 /* stabilize power with chip in reset (nRESET), and
295 * both spi_sck_bit and usi_sck_bit clear (CPOL=0)
296 */
297 pp->lastbyte |= vcc_bits;
298 parport_write_data(pp->port, pp->lastbyte);
299 msleep(5);
300
301 /* take it out of reset; assume long reset delay */
302 pp->lastbyte |= butterfly_nreset;
303 parport_write_data(pp->port, pp->lastbyte);
304 msleep(100);
305
306
307 /*
308 * Start SPI ... for now, hide that we're two physical busses.
309 */
310 status = spi_bitbang_start(&pp->bitbang);
311 if (status < 0)
312 goto clean2;
313
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314 /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
315 * (firmware resets at45, acts as spi slave) or neither (we ignore
316 * both, AVR uses AT45). Here we expect firmware for the first option.
2e10c84b 317 */
1fc7547d 318
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319 pp->info[0].max_speed_hz = 15 * 1000 * 1000;
320 strcpy(pp->info[0].modalias, "mtd_dataflash");
321 pp->info[0].platform_data = &flash;
322 pp->info[0].chip_select = 1;
323 pp->info[0].controller_data = pp;
324 pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
325 if (pp->dataflash)
326 pr_debug("%s: dataflash at %s\n", p->name,
327 pp->dataflash->dev.bus_id);
328
329#ifdef HAVE_USI
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330 /* Bus 2 is only for talking to the AVR, and it can work no
331 * matter who masters bus 1; needs appropriate AVR firmware.
332 */
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333 pp->info[1].max_speed_hz = 10 /* ?? */ * 1000 * 1000;
334 strcpy(pp->info[1].modalias, "butterfly");
335 // pp->info[1].platform_data = ... TBD ... ;
336 pp->info[1].chip_select = 2,
337 pp->info[1].controller_data = pp;
338 pp->butterfly = spi_new_device(pp->bitbang.master, &pp->info[1]);
339 if (pp->butterfly)
340 pr_debug("%s: butterfly at %s\n", p->name,
341 pp->butterfly->dev.bus_id);
342
343 /* FIXME setup ACK for the IRQ line ... */
344#endif
345
346 // dev_info(_what?_, ...)
347 pr_info("%s: AVR Butterfly\n", p->name);
348 butterfly = pp;
349 return;
350
351clean2:
352 /* turn off VCC */
353 parport_write_data(pp->port, 0);
354
355 parport_release(pp->pd);
356clean1:
357 parport_unregister_device(pd);
358clean0:
359 (void) spi_master_put(pp->bitbang.master);
360done:
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361 pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
362}
363
364static void butterfly_detach(struct parport *p)
365{
366 struct butterfly *pp;
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367 int status;
368
369 /* FIXME this global is ugly ... but, how to quickly get from
370 * the parport to the "struct butterfly" associated with it?
371 * "old school" driver-internal device lists?
372 */
373 if (!butterfly || butterfly->port != p)
374 return;
375 pp = butterfly;
376 butterfly = NULL;
377
9c1da3cb 378 /* stop() unregisters child devices too */
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379 status = spi_bitbang_stop(&pp->bitbang);
380
381 /* turn off VCC */
382 parport_write_data(pp->port, 0);
383 msleep(10);
384
385 parport_release(pp->pd);
386 parport_unregister_device(pp->pd);
387
2e10c84b 388 (void) spi_master_put(pp->bitbang.master);
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389}
390
391static struct parport_driver butterfly_driver = {
392 .name = "spi_butterfly",
393 .attach = butterfly_attach,
394 .detach = butterfly_detach,
395};
396
397
398static int __init butterfly_init(void)
399{
400 return parport_register_driver(&butterfly_driver);
401}
402device_initcall(butterfly_init);
403
404static void __exit butterfly_exit(void)
405{
406 parport_unregister_driver(&butterfly_driver);
407}
408module_exit(butterfly_exit);
409
9c1da3cb 410MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
2e10c84b 411MODULE_LICENSE("GPL");