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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 | */ | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/init.h> | |
22 | #include <linux/delay.h> | |
23 | #include <linux/device.h> | |
24 | #include <linux/parport.h> | |
25 | ||
26 | #include <linux/sched.h> | |
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 | ||
68 | static inline struct butterfly *spidev_to_pp(struct spi_device *spi) | |
69 | { | |
70 | return spi->controller_data; | |
71 | } | |
72 | ||
73 | static 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 | ||
83 | struct 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 | ||
107 | static inline void | |
108 | setsck(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 | ||
126 | static inline void | |
127 | setmosi(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 | ||
145 | static 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 | ||
161 | static void butterfly_chipselect(struct spi_device *spi, int value) | |
162 | { | |
163 | struct butterfly *pp = spidev_to_pp(spi); | |
164 | ||
165 | /* set default clock polarity */ | |
166 | if (value != BITBANG_CS_INACTIVE) | |
167 | setsck(spi, spi->mode & SPI_CPOL); | |
168 | ||
169 | /* no chipselect on this USI link config */ | |
170 | if (is_usidev(spi)) | |
171 | return; | |
172 | ||
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 | */ | |
177 | if (spi_cs_bit == PARPORT_CONTROL_INIT) | |
178 | value = !value; | |
179 | ||
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 | ||
192 | static u32 | |
193 | butterfly_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 */ | |
203 | static struct mtd_partition partitions[] = { { | |
204 | /* JFFS2 wants partitions of 4*N blocks for this device, | |
205 | * so sectors 0 and 1 can't be partitions by themselves. | |
206 | */ | |
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 | ||
224 | static 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 */ | |
232 | static struct butterfly *butterfly; | |
233 | ||
234 | static void butterfly_attach(struct parport *p) | |
235 | { | |
236 | struct pardevice *pd; | |
237 | int status; | |
238 | struct butterfly *pp; | |
239 | struct spi_master *master; | |
240 | struct device *dev = p->physport->dev; | |
241 | ||
242 | if (butterfly || !dev) | |
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 | ||
249 | master = spi_alloc_master(dev, sizeof *pp); | |
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 | ||
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. | |
317 | */ | |
318 | ||
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 | |
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 | */ | |
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 | ||
351 | clean2: | |
352 | /* turn off VCC */ | |
353 | parport_write_data(pp->port, 0); | |
354 | ||
355 | parport_release(pp->pd); | |
356 | clean1: | |
357 | parport_unregister_device(pd); | |
358 | clean0: | |
359 | (void) spi_master_put(pp->bitbang.master); | |
360 | done: | |
361 | pr_debug("%s: butterfly probe, fail %d\n", p->name, status); | |
362 | } | |
363 | ||
364 | static void butterfly_detach(struct parport *p) | |
365 | { | |
366 | struct butterfly *pp; | |
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 | ||
378 | /* stop() unregisters child devices too */ | |
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 | ||
388 | (void) spi_master_put(pp->bitbang.master); | |
389 | } | |
390 | ||
391 | static struct parport_driver butterfly_driver = { | |
392 | .name = "spi_butterfly", | |
393 | .attach = butterfly_attach, | |
394 | .detach = butterfly_detach, | |
395 | }; | |
396 | ||
397 | ||
398 | static int __init butterfly_init(void) | |
399 | { | |
400 | return parport_register_driver(&butterfly_driver); | |
401 | } | |
402 | device_initcall(butterfly_init); | |
403 | ||
404 | static void __exit butterfly_exit(void) | |
405 | { | |
406 | parport_unregister_driver(&butterfly_driver); | |
407 | } | |
408 | module_exit(butterfly_exit); | |
409 | ||
410 | MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly"); | |
411 | MODULE_LICENSE("GPL"); |