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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 | |
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 |
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 |
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 | |
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 | |
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 |
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 | |
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 | |
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 | |
344 | static int __init butterfly_init(void) |
345 | { |
346 | return parport_register_driver(&butterfly_driver); |
347 | } |
348 | device_initcall(butterfly_init); |
349 | |
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 |
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