1 /*
2 * 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/module.h>
24 #include <linux/device.h>
25 #include <linux/parport.h>
26
27 #include <linux/sched.h>
28 #include <linux/spi/spi.h>
29 #include <linux/spi/spi_bitbang.h>
30 #include <linux/spi/flash.h>
31
32 #include <linux/mtd/partitions.h>
33
34
35 /*
36 * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
37 * with a battery powered AVR microcontroller and lots of goodies. You
38 * can use GCC to develop firmware for this.
39 *
40 * See Documentation/spi/butterfly for information about how to build
41 * and use this custom parallel port cable.
42 */
43
44
45 /* DATA output bits (pins 2..9 == D0..D7) */
46 #define butterfly_nreset (1 << 1) /* pin 3 */
47
48 #define spi_sck_bit (1 << 0) /* pin 2 */
49 #define spi_mosi_bit (1 << 7) /* pin 9 */
50
51 #define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */
52
53 /* STATUS input bits */
54 #define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */
55
56 /* CONTROL output bits */
57 #define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */
58
59
60
spidev_to_pp(struct spi_device * spi)61 static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
62 {
63 return spi->controller_data;
64 }
65
66
67 struct butterfly {
68 /* REVISIT ... for now, this must be first */
69 struct spi_bitbang bitbang;
70
71 struct parport *port;
72 struct pardevice *pd;
73
74 u8 lastbyte;
75
76 struct spi_device *dataflash;
77 struct spi_device *butterfly;
78 struct spi_board_info info[2];
79
80 };
81
82 /*----------------------------------------------------------------------*/
83
84 static inline void
setsck(struct spi_device * spi,int is_on)85 setsck(struct spi_device *spi, int is_on)
86 {
87 struct butterfly *pp = spidev_to_pp(spi);
88 u8 bit, byte = pp->lastbyte;
89
90 bit = spi_sck_bit;
91
92 if (is_on)
93 byte |= bit;
94 else
95 byte &= ~bit;
96 parport_write_data(pp->port, byte);
97 pp->lastbyte = byte;
98 }
99
100 static inline void
setmosi(struct spi_device * spi,int is_on)101 setmosi(struct spi_device *spi, int is_on)
102 {
103 struct butterfly *pp = spidev_to_pp(spi);
104 u8 bit, byte = pp->lastbyte;
105
106 bit = spi_mosi_bit;
107
108 if (is_on)
109 byte |= bit;
110 else
111 byte &= ~bit;
112 parport_write_data(pp->port, byte);
113 pp->lastbyte = byte;
114 }
115
getmiso(struct spi_device * spi)116 static inline int getmiso(struct spi_device *spi)
117 {
118 struct butterfly *pp = spidev_to_pp(spi);
119 int value;
120 u8 bit;
121
122 bit = spi_miso_bit;
123
124 /* only STATUS_BUSY is NOT negated */
125 value = !(parport_read_status(pp->port) & bit);
126 return (bit == PARPORT_STATUS_BUSY) ? value : !value;
127 }
128
butterfly_chipselect(struct spi_device * spi,int value)129 static void butterfly_chipselect(struct spi_device *spi, int value)
130 {
131 struct butterfly *pp = spidev_to_pp(spi);
132
133 /* set default clock polarity */
134 if (value != BITBANG_CS_INACTIVE)
135 setsck(spi, spi->mode & SPI_CPOL);
136
137 /* here, value == "activate or not";
138 * most PARPORT_CONTROL_* bits are negated, so we must
139 * morph it to value == "bit value to write in control register"
140 */
141 if (spi_cs_bit == PARPORT_CONTROL_INIT)
142 value = !value;
143
144 parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
145 }
146
147
148 /* we only needed to implement one mode here, and choose SPI_MODE_0 */
149
150 #define spidelay(X) do{}while(0)
151 //#define spidelay ndelay
152
153 #include "spi-bitbang-txrx.h"
154
155 static u32
butterfly_txrx_word_mode0(struct spi_device * spi,unsigned nsecs,u32 word,u8 bits)156 butterfly_txrx_word_mode0(struct spi_device *spi,
157 unsigned nsecs,
158 u32 word, u8 bits)
159 {
160 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
161 }
162
163 /*----------------------------------------------------------------------*/
164
165 /* override default partitioning with cmdlinepart */
166 static struct mtd_partition partitions[] = { {
167 /* JFFS2 wants partitions of 4*N blocks for this device,
168 * so sectors 0 and 1 can't be partitions by themselves.
169 */
170
171 /* sector 0 = 8 pages * 264 bytes/page (1 block)
172 * sector 1 = 248 pages * 264 bytes/page
173 */
174 .name = "bookkeeping", // 66 KB
175 .offset = 0,
176 .size = (8 + 248) * 264,
177 // .mask_flags = MTD_WRITEABLE,
178 }, {
179 /* sector 2 = 256 pages * 264 bytes/page
180 * sectors 3-5 = 512 pages * 264 bytes/page
181 */
182 .name = "filesystem", // 462 KB
183 .offset = MTDPART_OFS_APPEND,
184 .size = MTDPART_SIZ_FULL,
185 } };
186
187 static struct flash_platform_data flash = {
188 .name = "butterflash",
189 .parts = partitions,
190 .nr_parts = ARRAY_SIZE(partitions),
191 };
192
193
194 /* REVISIT remove this ugly global and its "only one" limitation */
195 static struct butterfly *butterfly;
196
butterfly_attach(struct parport * p)197 static void butterfly_attach(struct parport *p)
198 {
199 struct pardevice *pd;
200 int status;
201 struct butterfly *pp;
202 struct spi_master *master;
203 struct device *dev = p->physport->dev;
204
205 if (butterfly || !dev)
206 return;
207
208 /* REVISIT: this just _assumes_ a butterfly is there ... no probe,
209 * and no way to be selective about what it binds to.
210 */
211
212 master = spi_alloc_master(dev, sizeof *pp);
213 if (!master) {
214 status = -ENOMEM;
215 goto done;
216 }
217 pp = spi_master_get_devdata(master);
218
219 /*
220 * SPI and bitbang hookup
221 *
222 * use default setup(), cleanup(), and transfer() methods; and
223 * only bother implementing mode 0. Start it later.
224 */
225 master->bus_num = 42;
226 master->num_chipselect = 2;
227
228 pp->bitbang.master = spi_master_get(master);
229 pp->bitbang.chipselect = butterfly_chipselect;
230 pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
231
232 /*
233 * parport hookup
234 */
235 pp->port = p;
236 pd = parport_register_device(p, "spi_butterfly",
237 NULL, NULL, NULL,
238 0 /* FLAGS */, pp);
239 if (!pd) {
240 status = -ENOMEM;
241 goto clean0;
242 }
243 pp->pd = pd;
244
245 status = parport_claim(pd);
246 if (status < 0)
247 goto clean1;
248
249 /*
250 * Butterfly reset, powerup, run firmware
251 */
252 pr_debug("%s: powerup/reset Butterfly\n", p->name);
253
254 /* nCS for dataflash (this bit is inverted on output) */
255 parport_frob_control(pp->port, spi_cs_bit, 0);
256
257 /* stabilize power with chip in reset (nRESET), and
258 * spi_sck_bit clear (CPOL=0)
259 */
260 pp->lastbyte |= vcc_bits;
261 parport_write_data(pp->port, pp->lastbyte);
262 msleep(5);
263
264 /* take it out of reset; assume long reset delay */
265 pp->lastbyte |= butterfly_nreset;
266 parport_write_data(pp->port, pp->lastbyte);
267 msleep(100);
268
269
270 /*
271 * Start SPI ... for now, hide that we're two physical busses.
272 */
273 status = spi_bitbang_start(&pp->bitbang);
274 if (status < 0)
275 goto clean2;
276
277 /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
278 * (firmware resets at45, acts as spi slave) or neither (we ignore
279 * both, AVR uses AT45). Here we expect firmware for the first option.
280 */
281
282 pp->info[0].max_speed_hz = 15 * 1000 * 1000;
283 strcpy(pp->info[0].modalias, "mtd_dataflash");
284 pp->info[0].platform_data = &flash;
285 pp->info[0].chip_select = 1;
286 pp->info[0].controller_data = pp;
287 pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
288 if (pp->dataflash)
289 pr_debug("%s: dataflash at %s\n", p->name,
290 dev_name(&pp->dataflash->dev));
291
292 // dev_info(_what?_, ...)
293 pr_info("%s: AVR Butterfly\n", p->name);
294 butterfly = pp;
295 return;
296
297 clean2:
298 /* turn off VCC */
299 parport_write_data(pp->port, 0);
300
301 parport_release(pp->pd);
302 clean1:
303 parport_unregister_device(pd);
304 clean0:
305 (void) spi_master_put(pp->bitbang.master);
306 done:
307 pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
308 }
309
butterfly_detach(struct parport * p)310 static void butterfly_detach(struct parport *p)
311 {
312 struct butterfly *pp;
313 int status;
314
315 /* FIXME this global is ugly ... but, how to quickly get from
316 * the parport to the "struct butterfly" associated with it?
317 * "old school" driver-internal device lists?
318 */
319 if (!butterfly || butterfly->port != p)
320 return;
321 pp = butterfly;
322 butterfly = NULL;
323
324 /* stop() unregisters child devices too */
325 status = spi_bitbang_stop(&pp->bitbang);
326
327 /* turn off VCC */
328 parport_write_data(pp->port, 0);
329 msleep(10);
330
331 parport_release(pp->pd);
332 parport_unregister_device(pp->pd);
333
334 (void) spi_master_put(pp->bitbang.master);
335 }
336
337 static struct parport_driver butterfly_driver = {
338 .name = "spi_butterfly",
339 .attach = butterfly_attach,
340 .detach = butterfly_detach,
341 };
342
343
butterfly_init(void)344 static int __init butterfly_init(void)
345 {
346 return parport_register_driver(&butterfly_driver);
347 }
348 device_initcall(butterfly_init);
349
butterfly_exit(void)350 static void __exit butterfly_exit(void)
351 {
352 parport_unregister_driver(&butterfly_driver);
353 }
354 module_exit(butterfly_exit);
355
356 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
357 MODULE_LICENSE("GPL");
358