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#include <linux/kernel.h>
17#include <linux/init.h>
18#include <linux/delay.h>
19#include <linux/module.h>
20#include <linux/device.h>
21#include <linux/parport.h>
22
23#include <linux/sched.h>
24#include <linux/spi/spi.h>
25#include <linux/spi/spi_bitbang.h>
26#include <linux/spi/flash.h>
27
28#include <linux/mtd/partitions.h>
29
30
31/*
32 * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
33 * with a battery powered AVR microcontroller and lots of goodies.  You
34 * can use GCC to develop firmware for this.
35 *
36 * See Documentation/spi/butterfly for information about how to build
37 * and use this custom parallel port cable.
38 */
39
40
41/* DATA output bits (pins 2..9 == D0..D7) */
42#define	butterfly_nreset (1 << 1)		/* pin 3 */
43
44#define	spi_sck_bit	(1 << 0)		/* pin 2 */
45#define	spi_mosi_bit	(1 << 7)		/* pin 9 */
46
47#define	vcc_bits	((1 << 6) | (1 << 5))	/* pins 7, 8 */
48
49/* STATUS input bits */
50#define	spi_miso_bit	PARPORT_STATUS_BUSY	/* pin 11 */
51
52/* CONTROL output bits */
53#define	spi_cs_bit	PARPORT_CONTROL_SELECT	/* pin 17 */
54
55
56
57static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
58{
59	return spi->controller_data;
60}
61
62
63struct butterfly {
64	/* REVISIT ... for now, this must be first */
65	struct spi_bitbang	bitbang;
66
67	struct parport		*port;
68	struct pardevice	*pd;
69
70	u8			lastbyte;
71
72	struct spi_device	*dataflash;
73	struct spi_device	*butterfly;
74	struct spi_board_info	info[2];
75
76};
77
78/*----------------------------------------------------------------------*/
79
80static inline void
81setsck(struct spi_device *spi, int is_on)
82{
83	struct butterfly	*pp = spidev_to_pp(spi);
84	u8			bit, byte = pp->lastbyte;
85
86	bit = spi_sck_bit;
87
88	if (is_on)
89		byte |= bit;
90	else
91		byte &= ~bit;
92	parport_write_data(pp->port, byte);
93	pp->lastbyte = byte;
94}
95
96static inline void
97setmosi(struct spi_device *spi, int is_on)
98{
99	struct butterfly	*pp = spidev_to_pp(spi);
100	u8			bit, byte = pp->lastbyte;
101
102	bit = spi_mosi_bit;
103
104	if (is_on)
105		byte |= bit;
106	else
107		byte &= ~bit;
108	parport_write_data(pp->port, byte);
109	pp->lastbyte = byte;
110}
111
112static inline int getmiso(struct spi_device *spi)
113{
114	struct butterfly	*pp = spidev_to_pp(spi);
115	int			value;
116	u8			bit;
117
118	bit = spi_miso_bit;
119
120	/* only STATUS_BUSY is NOT negated */
121	value = !(parport_read_status(pp->port) & bit);
122	return (bit == PARPORT_STATUS_BUSY) ? value : !value;
123}
124
125static void butterfly_chipselect(struct spi_device *spi, int value)
126{
127	struct butterfly	*pp = spidev_to_pp(spi);
128
129	/* set default clock polarity */
130	if (value != BITBANG_CS_INACTIVE)
131		setsck(spi, spi->mode & SPI_CPOL);
132
133	/* here, value == "activate or not";
134	 * most PARPORT_CONTROL_* bits are negated, so we must
135	 * morph it to value == "bit value to write in control register"
136	 */
137	if (spi_cs_bit == PARPORT_CONTROL_INIT)
138		value = !value;
139
140	parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
141}
142
143
144/* we only needed to implement one mode here, and choose SPI_MODE_0 */
145
146#define spidelay(X)	do { } while (0)
147/* #define spidelay	ndelay */
148
149#include "spi-bitbang-txrx.h"
150
151static u32
152butterfly_txrx_word_mode0(struct spi_device *spi,
153		unsigned nsecs,
154		u32 word, u8 bits)
155{
156	return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
157}
158
159/*----------------------------------------------------------------------*/
160
161/* override default partitioning with cmdlinepart */
162static struct mtd_partition partitions[] = { {
163	/* JFFS2 wants partitions of 4*N blocks for this device,
164	 * so sectors 0 and 1 can't be partitions by themselves.
165	 */
166
167	/* sector 0 = 8 pages * 264 bytes/page (1 block)
168	 * sector 1 = 248 pages * 264 bytes/page
169	 */
170	.name		= "bookkeeping",	/* 66 KB */
171	.offset		= 0,
172	.size		= (8 + 248) * 264,
173	/* .mask_flags	= MTD_WRITEABLE, */
174}, {
175	/* sector 2 = 256 pages * 264 bytes/page
176	 * sectors 3-5 = 512 pages * 264 bytes/page
177	 */
178	.name		= "filesystem",		/* 462 KB */
179	.offset		= MTDPART_OFS_APPEND,
180	.size		= MTDPART_SIZ_FULL,
181} };
182
183static struct flash_platform_data flash = {
184	.name		= "butterflash",
185	.parts		= partitions,
186	.nr_parts	= ARRAY_SIZE(partitions),
187};
188
189
190/* REVISIT remove this ugly global and its "only one" limitation */
191static struct butterfly *butterfly;
192
193static void butterfly_attach(struct parport *p)
194{
195	struct pardevice	*pd;
196	int			status;
197	struct butterfly	*pp;
198	struct spi_master	*master;
199	struct device		*dev = p->physport->dev;
200
201	if (butterfly || !dev)
202		return;
203
204	/* REVISIT:  this just _assumes_ a butterfly is there ... no probe,
205	 * and no way to be selective about what it binds to.
206	 */
207
208	master = spi_alloc_master(dev, sizeof(*pp));
209	if (!master) {
210		status = -ENOMEM;
211		goto done;
212	}
213	pp = spi_master_get_devdata(master);
214
215	/*
216	 * SPI and bitbang hookup
217	 *
218	 * use default setup(), cleanup(), and transfer() methods; and
219	 * only bother implementing mode 0.  Start it later.
220	 */
221	master->bus_num = 42;
222	master->num_chipselect = 2;
223
224	pp->bitbang.master = master;
225	pp->bitbang.chipselect = butterfly_chipselect;
226	pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
227
228	/*
229	 * parport hookup
230	 */
231	pp->port = p;
232	pd = parport_register_device(p, "spi_butterfly",
233			NULL, NULL, NULL,
234			0 /* FLAGS */, pp);
235	if (!pd) {
236		status = -ENOMEM;
237		goto clean0;
238	}
239	pp->pd = pd;
240
241	status = parport_claim(pd);
242	if (status < 0)
243		goto clean1;
244
245	/*
246	 * Butterfly reset, powerup, run firmware
247	 */
248	pr_debug("%s: powerup/reset Butterfly\n", p->name);
249
250	/* nCS for dataflash (this bit is inverted on output) */
251	parport_frob_control(pp->port, spi_cs_bit, 0);
252
253	/* stabilize power with chip in reset (nRESET), and
254	 * spi_sck_bit clear (CPOL=0)
255	 */
256	pp->lastbyte |= vcc_bits;
257	parport_write_data(pp->port, pp->lastbyte);
258	msleep(5);
259
260	/* take it out of reset; assume long reset delay */
261	pp->lastbyte |= butterfly_nreset;
262	parport_write_data(pp->port, pp->lastbyte);
263	msleep(100);
264
265
266	/*
267	 * Start SPI ... for now, hide that we're two physical busses.
268	 */
269	status = spi_bitbang_start(&pp->bitbang);
270	if (status < 0)
271		goto clean2;
272
273	/* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
274	 * (firmware resets at45, acts as spi slave) or neither (we ignore
275	 * both, AVR uses AT45).  Here we expect firmware for the first option.
276	 */
277
278	pp->info[0].max_speed_hz = 15 * 1000 * 1000;
279	strcpy(pp->info[0].modalias, "mtd_dataflash");
280	pp->info[0].platform_data = &flash;
281	pp->info[0].chip_select = 1;
282	pp->info[0].controller_data = pp;
283	pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
284	if (pp->dataflash)
285		pr_debug("%s: dataflash at %s\n", p->name,
286				dev_name(&pp->dataflash->dev));
287
288	pr_info("%s: AVR Butterfly\n", p->name);
289	butterfly = pp;
290	return;
291
292clean2:
293	/* turn off VCC */
294	parport_write_data(pp->port, 0);
295
296	parport_release(pp->pd);
297clean1:
298	parport_unregister_device(pd);
299clean0:
300	(void) spi_master_put(pp->bitbang.master);
301done:
302	pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
303}
304
305static void butterfly_detach(struct parport *p)
306{
307	struct butterfly	*pp;
308
309	/* FIXME this global is ugly ... but, how to quickly get from
310	 * the parport to the "struct butterfly" associated with it?
311	 * "old school" driver-internal device lists?
312	 */
313	if (!butterfly || butterfly->port != p)
314		return;
315	pp = butterfly;
316	butterfly = NULL;
317
318	/* stop() unregisters child devices too */
319	spi_bitbang_stop(&pp->bitbang);
320
321	/* turn off VCC */
322	parport_write_data(pp->port, 0);
323	msleep(10);
324
325	parport_release(pp->pd);
326	parport_unregister_device(pp->pd);
327
328	(void) spi_master_put(pp->bitbang.master);
329}
330
331static struct parport_driver butterfly_driver = {
332	.name =		"spi_butterfly",
333	.attach =	butterfly_attach,
334	.detach =	butterfly_detach,
335};
336
337
338static int __init butterfly_init(void)
339{
340	return parport_register_driver(&butterfly_driver);
341}
342device_initcall(butterfly_init);
343
344static void __exit butterfly_exit(void)
345{
346	parport_unregister_driver(&butterfly_driver);
347}
348module_exit(butterfly_exit);
349
350MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
351MODULE_LICENSE("GPL");
352