• Home
  • History
  • Annotate
  • Line#
  • Navigate
  • Raw
  • Download
  • only in /asuswrt-rt-n18u-9.0.0.4.380.2695/release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/spi/
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
44/* DATA output bits (pins 2..9 == D0..D7) */
45#define	butterfly_nreset (1 << 1)		/* pin 3 */
46
47#define	spi_sck_bit	(1 << 0)		/* pin 2 */
48#define	spi_mosi_bit	(1 << 7)		/* pin 9 */
49
50#define	vcc_bits	((1 << 6) | (1 << 5))	/* pins 7, 8 */
51
52/* STATUS input bits */
53#define	spi_miso_bit	PARPORT_STATUS_BUSY	/* pin 11 */
54
55/* CONTROL output bits */
56#define	spi_cs_bit	PARPORT_CONTROL_SELECT	/* pin 17 */
57
58
59
60static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
61{
62	return spi->controller_data;
63}
64
65
66struct butterfly {
67	/* REVISIT ... for now, this must be first */
68	struct spi_bitbang	bitbang;
69
70	struct parport		*port;
71	struct pardevice	*pd;
72
73	u8			lastbyte;
74
75	struct spi_device	*dataflash;
76	struct spi_device	*butterfly;
77	struct spi_board_info	info[2];
78
79};
80
81/*----------------------------------------------------------------------*/
82
83static inline void
84setsck(struct spi_device *spi, int is_on)
85{
86	struct butterfly	*pp = spidev_to_pp(spi);
87	u8			bit, byte = pp->lastbyte;
88
89	bit = spi_sck_bit;
90
91	if (is_on)
92		byte |= bit;
93	else
94		byte &= ~bit;
95	parport_write_data(pp->port, byte);
96	pp->lastbyte = byte;
97}
98
99static inline void
100setmosi(struct spi_device *spi, int is_on)
101{
102	struct butterfly	*pp = spidev_to_pp(spi);
103	u8			bit, byte = pp->lastbyte;
104
105	bit = spi_mosi_bit;
106
107	if (is_on)
108		byte |= bit;
109	else
110		byte &= ~bit;
111	parport_write_data(pp->port, byte);
112	pp->lastbyte = byte;
113}
114
115static inline int getmiso(struct spi_device *spi)
116{
117	struct butterfly	*pp = spidev_to_pp(spi);
118	int			value;
119	u8			bit;
120
121	bit = spi_miso_bit;
122
123	/* only STATUS_BUSY is NOT negated */
124	value = !(parport_read_status(pp->port) & bit);
125	return (bit == PARPORT_STATUS_BUSY) ? value : !value;
126}
127
128static void butterfly_chipselect(struct spi_device *spi, int value)
129{
130	struct butterfly	*pp = spidev_to_pp(spi);
131
132	/* set default clock polarity */
133	if (value != BITBANG_CS_INACTIVE)
134		setsck(spi, spi->mode & SPI_CPOL);
135
136	/* here, value == "activate or not";
137	 * most PARPORT_CONTROL_* bits are negated, so we must
138	 * morph it to value == "bit value to write in control register"
139	 */
140	if (spi_cs_bit == PARPORT_CONTROL_INIT)
141		value = !value;
142
143	parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
144}
145
146
147/* we only needed to implement one mode here, and choose SPI_MODE_0 */
148
149#define	spidelay(X)	do{}while(0)
150//#define	spidelay	ndelay
151
152#include "spi_bitbang_txrx.h"
153
154static u32
155butterfly_txrx_word_mode0(struct spi_device *spi,
156		unsigned nsecs,
157		u32 word, u8 bits)
158{
159	return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
160}
161
162/*----------------------------------------------------------------------*/
163
164/* override default partitioning with cmdlinepart */
165static struct mtd_partition partitions[] = { {
166	/* JFFS2 wants partitions of 4*N blocks for this device,
167	 * so sectors 0 and 1 can't be partitions by themselves.
168	 */
169
170	/* sector 0 = 8 pages * 264 bytes/page (1 block)
171	 * sector 1 = 248 pages * 264 bytes/page
172	 */
173	.name		= "bookkeeping",	// 66 KB
174	.offset		= 0,
175	.size		= (8 + 248) * 264,
176//	.mask_flags	= MTD_WRITEABLE,
177}, {
178	/* sector 2 = 256 pages * 264 bytes/page
179	 * sectors 3-5 = 512 pages * 264 bytes/page
180	 */
181	.name		= "filesystem",		// 462 KB
182	.offset		= MTDPART_OFS_APPEND,
183	.size		= MTDPART_SIZ_FULL,
184} };
185
186static struct flash_platform_data flash = {
187	.name		= "butterflash",
188	.parts		= partitions,
189	.nr_parts	= ARRAY_SIZE(partitions),
190};
191
192
193/* REVISIT remove this ugly global and its "only one" limitation */
194static struct butterfly *butterfly;
195
196static void butterfly_attach(struct parport *p)
197{
198	struct pardevice	*pd;
199	int			status;
200	struct butterfly	*pp;
201	struct spi_master	*master;
202	struct device		*dev = p->physport->dev;
203
204	if (butterfly || !dev)
205		return;
206
207	/* REVISIT:  this just _assumes_ a butterfly is there ... no probe,
208	 * and no way to be selective about what it binds to.
209	 */
210
211	master = spi_alloc_master(dev, sizeof *pp);
212	if (!master) {
213		status = -ENOMEM;
214		goto done;
215	}
216	pp = spi_master_get_devdata(master);
217
218	/*
219	 * SPI and bitbang hookup
220	 *
221	 * use default setup(), cleanup(), and transfer() methods; and
222	 * only bother implementing mode 0.  Start it later.
223	 */
224	master->bus_num = 42;
225	master->num_chipselect = 2;
226
227	pp->bitbang.master = spi_master_get(master);
228	pp->bitbang.chipselect = butterfly_chipselect;
229	pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
230
231	/*
232	 * parport hookup
233	 */
234	pp->port = p;
235	pd = parport_register_device(p, "spi_butterfly",
236			NULL, NULL, NULL,
237			0 /* FLAGS */, pp);
238	if (!pd) {
239		status = -ENOMEM;
240		goto clean0;
241	}
242	pp->pd = pd;
243
244	status = parport_claim(pd);
245	if (status < 0)
246		goto clean1;
247
248	/*
249	 * Butterfly reset, powerup, run firmware
250	 */
251	pr_debug("%s: powerup/reset Butterfly\n", p->name);
252
253	/* nCS for dataflash (this bit is inverted on output) */
254	parport_frob_control(pp->port, spi_cs_bit, 0);
255
256	/* stabilize power with chip in reset (nRESET), and
257	 * spi_sck_bit clear (CPOL=0)
258	 */
259	pp->lastbyte |= vcc_bits;
260	parport_write_data(pp->port, pp->lastbyte);
261	msleep(5);
262
263	/* take it out of reset; assume long reset delay */
264	pp->lastbyte |= butterfly_nreset;
265	parport_write_data(pp->port, pp->lastbyte);
266	msleep(100);
267
268
269	/*
270	 * Start SPI ... for now, hide that we're two physical busses.
271	 */
272	status = spi_bitbang_start(&pp->bitbang);
273	if (status < 0)
274		goto clean2;
275
276	/* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
277	 * (firmware resets at45, acts as spi slave) or neither (we ignore
278	 * both, AVR uses AT45).  Here we expect firmware for the first option.
279	 */
280
281	pp->info[0].max_speed_hz = 15 * 1000 * 1000;
282	strcpy(pp->info[0].modalias, "mtd_dataflash");
283	pp->info[0].platform_data = &flash;
284	pp->info[0].chip_select = 1;
285	pp->info[0].controller_data = pp;
286	pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
287	if (pp->dataflash)
288		pr_debug("%s: dataflash at %s\n", p->name,
289				dev_name(&pp->dataflash->dev));
290
291	// dev_info(_what?_, ...)
292	pr_info("%s: AVR Butterfly\n", p->name);
293	butterfly = pp;
294	return;
295
296clean2:
297	/* turn off VCC */
298	parport_write_data(pp->port, 0);
299
300	parport_release(pp->pd);
301clean1:
302	parport_unregister_device(pd);
303clean0:
304	(void) spi_master_put(pp->bitbang.master);
305done:
306	pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
307}
308
309static void butterfly_detach(struct parport *p)
310{
311	struct butterfly	*pp;
312	int			status;
313
314	if (!butterfly || butterfly->port != p)
315		return;
316	pp = butterfly;
317	butterfly = NULL;
318
319	/* stop() unregisters child devices too */
320	status = spi_bitbang_stop(&pp->bitbang);
321
322	/* turn off VCC */
323	parport_write_data(pp->port, 0);
324	msleep(10);
325
326	parport_release(pp->pd);
327	parport_unregister_device(pp->pd);
328
329	(void) spi_master_put(pp->bitbang.master);
330}
331
332static struct parport_driver butterfly_driver = {
333	.name =		"spi_butterfly",
334	.attach =	butterfly_attach,
335	.detach =	butterfly_detach,
336};
337
338
339static int __init butterfly_init(void)
340{
341	return parport_register_driver(&butterfly_driver);
342}
343device_initcall(butterfly_init);
344
345static void __exit butterfly_exit(void)
346{
347	parport_unregister_driver(&butterfly_driver);
348}
349module_exit(butterfly_exit);
350
351MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
352MODULE_LICENSE("GPL");
353