2 * spi_butterfly.c - parport-to-butterfly adapter
4 * Copyright (C) 2005 David Brownell
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.
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.
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.
20 #include <linux/config.h>
21 #include <linux/kernel.h>
22 #include <linux/init.h>
23 #include <linux/delay.h>
24 #include <linux/platform_device.h>
25 #include <linux/parport.h>
27 #include <linux/spi/spi.h>
28 #include <linux/spi/spi_bitbang.h>
29 #include <linux/spi/flash.h>
31 #include <linux/mtd/partitions.h>
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.
39 * See Documentation/spi/butterfly for information about how to build
40 * and use this custom parallel port cable.
43 #undef HAVE_USI /* nyet */
46 /* DATA output bits (pins 2..9 == D0..D7) */
47 #define butterfly_nreset (1 << 1) /* pin 3 */
49 #define spi_sck_bit (1 << 0) /* pin 2 */
50 #define spi_mosi_bit (1 << 7) /* pin 9 */
52 #define usi_sck_bit (1 << 3) /* pin 5 */
53 #define usi_mosi_bit (1 << 4) /* pin 6 */
55 #define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */
57 /* STATUS input bits */
58 #define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */
60 #define usi_miso_bit PARPORT_STATUS_PAPEROUT /* pin 12 */
62 /* CONTROL output bits */
63 #define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */
64 /* USI uses no chipselect */
68 static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
70 return spi->controller_data;
73 static inline int is_usidev(struct spi_device *spi)
76 return spi->chip_select != 1;
84 /* REVISIT ... for now, this must be first */
85 struct spi_bitbang bitbang;
92 struct spi_device *dataflash;
93 struct spi_device *butterfly;
94 struct spi_board_info info[2];
98 /*----------------------------------------------------------------------*/
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.
108 setsck(struct spi_device *spi, int is_on)
110 struct butterfly *pp = spidev_to_pp(spi);
111 u8 bit, byte = pp->lastbyte;
122 parport_write_data(pp->port, byte);
127 setmosi(struct spi_device *spi, int is_on)
129 struct butterfly *pp = spidev_to_pp(spi);
130 u8 bit, byte = pp->lastbyte;
141 parport_write_data(pp->port, byte);
145 static inline int getmiso(struct spi_device *spi)
147 struct butterfly *pp = spidev_to_pp(spi);
156 /* only STATUS_BUSY is NOT negated */
157 value = !(parport_read_status(pp->port) & bit);
158 return (bit == PARPORT_STATUS_BUSY) ? value : !value;
161 static void butterfly_chipselect(struct spi_device *spi, int value)
163 struct butterfly *pp = spidev_to_pp(spi);
165 /* set default clock polarity */
166 if (value != BITBANG_CS_INACTIVE)
167 setsck(spi, spi->mode & SPI_CPOL);
169 /* no chipselect on this USI link config */
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"
177 if (spi_cs_bit == PARPORT_CONTROL_INIT)
180 parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
184 /* we only needed to implement one mode here, and choose SPI_MODE_0 */
186 #define spidelay(X) do{}while(0)
187 //#define spidelay ndelay
189 #define EXPAND_BITBANG_TXRX
190 #include <linux/spi/spi_bitbang.h>
193 butterfly_txrx_word_mode0(struct spi_device *spi,
197 return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits);
200 /*----------------------------------------------------------------------*/
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.
208 /* sector 0 = 8 pages * 264 bytes/page (1 block)
209 * sector 1 = 248 pages * 264 bytes/page
211 .name = "bookkeeping", // 66 KB
213 .size = (8 + 248) * 264,
214 // .mask_flags = MTD_WRITEABLE,
216 /* sector 2 = 256 pages * 264 bytes/page
217 * sectors 3-5 = 512 pages * 264 bytes/page
219 .name = "filesystem", // 462 KB
220 .offset = MTDPART_OFS_APPEND,
221 .size = MTDPART_SIZ_FULL,
224 static struct flash_platform_data flash = {
225 .name = "butterflash",
227 .nr_parts = ARRAY_SIZE(partitions),
231 /* REVISIT remove this ugly global and its "only one" limitation */
232 static struct butterfly *butterfly;
234 static void butterfly_attach(struct parport *p)
236 struct pardevice *pd;
238 struct butterfly *pp;
239 struct spi_master *master;
240 struct platform_device *pdev;
245 /* REVISIT: this just _assumes_ a butterfly is there ... no probe,
246 * and no way to be selective about what it binds to.
249 /* FIXME where should master->cdev.dev come from?
250 * e.g. /sys/bus/pnp0/00:0b, some PCI thing, etc
251 * setting up a platform device like this is an ugly kluge...
253 pdev = platform_device_register_simple("butterfly", -1, NULL, 0);
255 master = spi_alloc_master(&pdev->dev, sizeof *pp);
260 pp = spi_master_get_devdata(master);
263 * SPI and bitbang hookup
265 * use default setup(), cleanup(), and transfer() methods; and
266 * only bother implementing mode 0. Start it later.
268 master->bus_num = 42;
269 master->num_chipselect = 2;
271 pp->bitbang.master = spi_master_get(master);
272 pp->bitbang.chipselect = butterfly_chipselect;
273 pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
279 pd = parport_register_device(p, "spi_butterfly",
288 status = parport_claim(pd);
293 * Butterfly reset, powerup, run firmware
295 pr_debug("%s: powerup/reset Butterfly\n", p->name);
297 /* nCS for dataflash (this bit is inverted on output) */
298 parport_frob_control(pp->port, spi_cs_bit, 0);
300 /* stabilize power with chip in reset (nRESET), and
301 * both spi_sck_bit and usi_sck_bit clear (CPOL=0)
303 pp->lastbyte |= vcc_bits;
304 parport_write_data(pp->port, pp->lastbyte);
307 /* take it out of reset; assume long reset delay */
308 pp->lastbyte |= butterfly_nreset;
309 parport_write_data(pp->port, pp->lastbyte);
314 * Start SPI ... for now, hide that we're two physical busses.
316 status = spi_bitbang_start(&pp->bitbang);
320 /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
321 * (firmware resets at45, acts as spi slave) or neither (we ignore
322 * both, AVR uses AT45). Here we expect firmware for the first option.
325 pp->info[0].max_speed_hz = 15 * 1000 * 1000;
326 strcpy(pp->info[0].modalias, "mtd_dataflash");
327 pp->info[0].platform_data = &flash;
328 pp->info[0].chip_select = 1;
329 pp->info[0].controller_data = pp;
330 pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
332 pr_debug("%s: dataflash at %s\n", p->name,
333 pp->dataflash->dev.bus_id);
336 /* Bus 2 is only for talking to the AVR, and it can work no
337 * matter who masters bus 1; needs appropriate AVR firmware.
339 pp->info[1].max_speed_hz = 10 /* ?? */ * 1000 * 1000;
340 strcpy(pp->info[1].modalias, "butterfly");
341 // pp->info[1].platform_data = ... TBD ... ;
342 pp->info[1].chip_select = 2,
343 pp->info[1].controller_data = pp;
344 pp->butterfly = spi_new_device(pp->bitbang.master, &pp->info[1]);
346 pr_debug("%s: butterfly at %s\n", p->name,
347 pp->butterfly->dev.bus_id);
349 /* FIXME setup ACK for the IRQ line ... */
352 // dev_info(_what?_, ...)
353 pr_info("%s: AVR Butterfly\n", p->name);
359 parport_write_data(pp->port, 0);
361 parport_release(pp->pd);
363 parport_unregister_device(pd);
365 (void) spi_master_put(pp->bitbang.master);
367 platform_device_unregister(pdev);
368 pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
371 static void butterfly_detach(struct parport *p)
373 struct butterfly *pp;
374 struct platform_device *pdev;
377 /* FIXME this global is ugly ... but, how to quickly get from
378 * the parport to the "struct butterfly" associated with it?
379 * "old school" driver-internal device lists?
381 if (!butterfly || butterfly->port != p)
386 /* stop() unregisters child devices too */
387 pdev = to_platform_device(pp->bitbang.master->cdev.dev);
388 status = spi_bitbang_stop(&pp->bitbang);
391 parport_write_data(pp->port, 0);
394 parport_release(pp->pd);
395 parport_unregister_device(pp->pd);
397 (void) spi_master_put(pp->bitbang.master);
399 platform_device_unregister(pdev);
402 static struct parport_driver butterfly_driver = {
403 .name = "spi_butterfly",
404 .attach = butterfly_attach,
405 .detach = butterfly_detach,
409 static int __init butterfly_init(void)
411 return parport_register_driver(&butterfly_driver);
413 device_initcall(butterfly_init);
415 static void __exit butterfly_exit(void)
417 parport_unregister_driver(&butterfly_driver);
419 module_exit(butterfly_exit);
421 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
422 MODULE_LICENSE("GPL");