1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * parport-to-butterfly adapter
5 * Copyright (C) 2005 David Brownell
7 #include <linux/kernel.h>
8 #include <linux/init.h>
9 #include <linux/delay.h>
10 #include <linux/module.h>
11 #include <linux/device.h>
12 #include <linux/parport.h>
14 #include <linux/sched.h>
15 #include <linux/spi/spi.h>
16 #include <linux/spi/spi_bitbang.h>
17 #include <linux/spi/flash.h>
19 #include <linux/mtd/partitions.h>
22 * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
23 * with a battery powered AVR microcontroller and lots of goodies. You
24 * can use GCC to develop firmware for this.
26 * See Documentation/spi/butterfly for information about how to build
27 * and use this custom parallel port cable.
30 /* DATA output bits (pins 2..9 == D0..D7) */
31 #define butterfly_nreset (1 << 1) /* pin 3 */
33 #define spi_sck_bit (1 << 0) /* pin 2 */
34 #define spi_mosi_bit (1 << 7) /* pin 9 */
36 #define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */
38 /* STATUS input bits */
39 #define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */
41 /* CONTROL output bits */
42 #define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */
44 static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
46 return spi->controller_data;
50 /* REVISIT ... for now, this must be first */
51 struct spi_bitbang bitbang;
58 struct spi_device *dataflash;
59 struct spi_device *butterfly;
60 struct spi_board_info info[2];
64 /*----------------------------------------------------------------------*/
67 setsck(struct spi_device *spi, int is_on)
69 struct butterfly *pp = spidev_to_pp(spi);
70 u8 bit, byte = pp->lastbyte;
78 parport_write_data(pp->port, byte);
83 setmosi(struct spi_device *spi, int is_on)
85 struct butterfly *pp = spidev_to_pp(spi);
86 u8 bit, byte = pp->lastbyte;
94 parport_write_data(pp->port, byte);
98 static inline int getmiso(struct spi_device *spi)
100 struct butterfly *pp = spidev_to_pp(spi);
106 /* only STATUS_BUSY is NOT negated */
107 value = !(parport_read_status(pp->port) & bit);
108 return (bit == PARPORT_STATUS_BUSY) ? value : !value;
111 static void butterfly_chipselect(struct spi_device *spi, int value)
113 struct butterfly *pp = spidev_to_pp(spi);
115 /* set default clock polarity */
116 if (value != BITBANG_CS_INACTIVE)
117 setsck(spi, spi->mode & SPI_CPOL);
119 /* here, value == "activate or not";
120 * most PARPORT_CONTROL_* bits are negated, so we must
121 * morph it to value == "bit value to write in control register"
123 if (spi_cs_bit == PARPORT_CONTROL_INIT)
126 parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
129 /* we only needed to implement one mode here, and choose SPI_MODE_0 */
131 #define spidelay(X) do { } while (0)
132 /* #define spidelay ndelay */
134 #include "spi-bitbang-txrx.h"
137 butterfly_txrx_word_mode0(struct spi_device *spi, unsigned nsecs, u32 word,
138 u8 bits, unsigned flags)
140 return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
143 /*----------------------------------------------------------------------*/
145 /* override default partitioning with cmdlinepart */
146 static struct mtd_partition partitions[] = { {
147 /* JFFS2 wants partitions of 4*N blocks for this device,
148 * so sectors 0 and 1 can't be partitions by themselves.
151 /* sector 0 = 8 pages * 264 bytes/page (1 block)
152 * sector 1 = 248 pages * 264 bytes/page
154 .name = "bookkeeping", /* 66 KB */
156 .size = (8 + 248) * 264,
157 /* .mask_flags = MTD_WRITEABLE, */
159 /* sector 2 = 256 pages * 264 bytes/page
160 * sectors 3-5 = 512 pages * 264 bytes/page
162 .name = "filesystem", /* 462 KB */
163 .offset = MTDPART_OFS_APPEND,
164 .size = MTDPART_SIZ_FULL,
167 static struct flash_platform_data flash = {
168 .name = "butterflash",
170 .nr_parts = ARRAY_SIZE(partitions),
173 /* REVISIT remove this ugly global and its "only one" limitation */
174 static struct butterfly *butterfly;
176 static void butterfly_attach(struct parport *p)
178 struct pardevice *pd;
180 struct butterfly *pp;
181 struct spi_master *master;
182 struct device *dev = p->physport->dev;
183 struct pardev_cb butterfly_cb;
185 if (butterfly || !dev)
188 /* REVISIT: this just _assumes_ a butterfly is there ... no probe,
189 * and no way to be selective about what it binds to.
192 master = spi_alloc_master(dev, sizeof(*pp));
197 pp = spi_master_get_devdata(master);
200 * SPI and bitbang hookup
202 * use default setup(), cleanup(), and transfer() methods; and
203 * only bother implementing mode 0. Start it later.
205 master->bus_num = 42;
206 master->num_chipselect = 2;
208 pp->bitbang.master = master;
209 pp->bitbang.chipselect = butterfly_chipselect;
210 pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
216 memset(&butterfly_cb, 0, sizeof(butterfly_cb));
217 butterfly_cb.private = pp;
218 pd = parport_register_dev_model(p, "spi_butterfly", &butterfly_cb, 0);
225 status = parport_claim(pd);
230 * Butterfly reset, powerup, run firmware
232 pr_debug("%s: powerup/reset Butterfly\n", p->name);
234 /* nCS for dataflash (this bit is inverted on output) */
235 parport_frob_control(pp->port, spi_cs_bit, 0);
237 /* stabilize power with chip in reset (nRESET), and
238 * spi_sck_bit clear (CPOL=0)
240 pp->lastbyte |= vcc_bits;
241 parport_write_data(pp->port, pp->lastbyte);
244 /* take it out of reset; assume long reset delay */
245 pp->lastbyte |= butterfly_nreset;
246 parport_write_data(pp->port, pp->lastbyte);
250 * Start SPI ... for now, hide that we're two physical busses.
252 status = spi_bitbang_start(&pp->bitbang);
256 /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
257 * (firmware resets at45, acts as spi slave) or neither (we ignore
258 * both, AVR uses AT45). Here we expect firmware for the first option.
261 pp->info[0].max_speed_hz = 15 * 1000 * 1000;
262 strcpy(pp->info[0].modalias, "mtd_dataflash");
263 pp->info[0].platform_data = &flash;
264 pp->info[0].chip_select = 1;
265 pp->info[0].controller_data = pp;
266 pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
268 pr_debug("%s: dataflash at %s\n", p->name,
269 dev_name(&pp->dataflash->dev));
271 pr_info("%s: AVR Butterfly\n", p->name);
277 parport_write_data(pp->port, 0);
279 parport_release(pp->pd);
281 parport_unregister_device(pd);
283 spi_master_put(pp->bitbang.master);
285 pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
288 static void butterfly_detach(struct parport *p)
290 struct butterfly *pp;
292 /* FIXME this global is ugly ... but, how to quickly get from
293 * the parport to the "struct butterfly" associated with it?
294 * "old school" driver-internal device lists?
296 if (!butterfly || butterfly->port != p)
301 /* stop() unregisters child devices too */
302 spi_bitbang_stop(&pp->bitbang);
305 parport_write_data(pp->port, 0);
308 parport_release(pp->pd);
309 parport_unregister_device(pp->pd);
311 spi_master_put(pp->bitbang.master);
314 static struct parport_driver butterfly_driver = {
315 .name = "spi_butterfly",
316 .match_port = butterfly_attach,
317 .detach = butterfly_detach,
321 static int __init butterfly_init(void)
323 return parport_register_driver(&butterfly_driver);
325 device_initcall(butterfly_init);
327 static void __exit butterfly_exit(void)
329 parport_unregister_driver(&butterfly_driver);
331 module_exit(butterfly_exit);
333 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
334 MODULE_LICENSE("GPL");