1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * parport-to-butterfly adapter |
4 | * |
5 | * Copyright (C) 2005 David Brownell |
6 | */ |
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> |
13 | |
14 | #include <linux/sched.h> |
15 | #include <linux/spi/spi.h> |
16 | #include <linux/spi/spi_bitbang.h> |
17 | #include <linux/spi/flash.h> |
18 | |
19 | #include <linux/mtd/partitions.h> |
20 | |
21 | /* |
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. |
25 | * |
26 | * See Documentation/spi/butterfly.rst for information about how to build |
27 | * and use this custom parallel port cable. |
28 | */ |
29 | |
30 | /* DATA output bits (pins 2..9 == D0..D7) */ |
31 | #define butterfly_nreset (1 << 1) /* pin 3 */ |
32 | |
33 | #define spi_sck_bit (1 << 0) /* pin 2 */ |
34 | #define spi_mosi_bit (1 << 7) /* pin 9 */ |
35 | |
36 | #define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */ |
37 | |
38 | /* STATUS input bits */ |
39 | #define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */ |
40 | |
41 | /* CONTROL output bits */ |
42 | #define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */ |
43 | |
44 | static inline struct butterfly *spidev_to_pp(struct spi_device *spi) |
45 | { |
46 | return spi->controller_data; |
47 | } |
48 | |
49 | struct butterfly { |
50 | /* REVISIT ... for now, this must be first */ |
51 | struct spi_bitbang bitbang; |
52 | |
53 | struct parport *port; |
54 | struct pardevice *pd; |
55 | |
56 | u8 lastbyte; |
57 | |
58 | struct spi_device *dataflash; |
59 | struct spi_device *butterfly; |
60 | struct spi_board_info info[2]; |
61 | |
62 | }; |
63 | |
64 | /*----------------------------------------------------------------------*/ |
65 | |
66 | static inline void |
67 | setsck(struct spi_device *spi, int is_on) |
68 | { |
69 | struct butterfly *pp = spidev_to_pp(spi); |
70 | u8 bit, byte = pp->lastbyte; |
71 | |
72 | bit = spi_sck_bit; |
73 | |
74 | if (is_on) |
75 | byte |= bit; |
76 | else |
77 | byte &= ~bit; |
78 | parport_write_data(pp->port, byte); |
79 | pp->lastbyte = byte; |
80 | } |
81 | |
82 | static inline void |
83 | setmosi(struct spi_device *spi, int is_on) |
84 | { |
85 | struct butterfly *pp = spidev_to_pp(spi); |
86 | u8 bit, byte = pp->lastbyte; |
87 | |
88 | bit = spi_mosi_bit; |
89 | |
90 | if (is_on) |
91 | byte |= bit; |
92 | else |
93 | byte &= ~bit; |
94 | parport_write_data(pp->port, byte); |
95 | pp->lastbyte = byte; |
96 | } |
97 | |
98 | static inline int getmiso(struct spi_device *spi) |
99 | { |
100 | struct butterfly *pp = spidev_to_pp(spi); |
101 | int value; |
102 | u8 bit; |
103 | |
104 | bit = spi_miso_bit; |
105 | |
106 | /* only STATUS_BUSY is NOT negated */ |
107 | value = !(parport_read_status(pp->port) & bit); |
108 | return (bit == PARPORT_STATUS_BUSY) ? value : !value; |
109 | } |
110 | |
111 | static void butterfly_chipselect(struct spi_device *spi, int value) |
112 | { |
113 | struct butterfly *pp = spidev_to_pp(spi); |
114 | |
115 | /* set default clock polarity */ |
116 | if (value != BITBANG_CS_INACTIVE) |
117 | setsck(spi, is_on: spi->mode & SPI_CPOL); |
118 | |
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" |
122 | */ |
123 | if (spi_cs_bit == PARPORT_CONTROL_INIT) |
124 | value = !value; |
125 | |
126 | parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0); |
127 | } |
128 | |
129 | /* we only needed to implement one mode here, and choose SPI_MODE_0 */ |
130 | |
131 | #define spidelay(X) do { } while (0) |
132 | /* #define spidelay ndelay */ |
133 | |
134 | #include "spi-bitbang-txrx.h" |
135 | |
136 | static u32 |
137 | butterfly_txrx_word_mode0(struct spi_device *spi, unsigned nsecs, u32 word, |
138 | u8 bits, unsigned flags) |
139 | { |
140 | return bitbang_txrx_be_cpha0(spi, nsecs, cpol: 0, flags, word, bits); |
141 | } |
142 | |
143 | /*----------------------------------------------------------------------*/ |
144 | |
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. |
149 | */ |
150 | |
151 | /* sector 0 = 8 pages * 264 bytes/page (1 block) |
152 | * sector 1 = 248 pages * 264 bytes/page |
153 | */ |
154 | .name = "bookkeeping" , /* 66 KB */ |
155 | .offset = 0, |
156 | .size = (8 + 248) * 264, |
157 | /* .mask_flags = MTD_WRITEABLE, */ |
158 | }, { |
159 | /* sector 2 = 256 pages * 264 bytes/page |
160 | * sectors 3-5 = 512 pages * 264 bytes/page |
161 | */ |
162 | .name = "filesystem" , /* 462 KB */ |
163 | .offset = MTDPART_OFS_APPEND, |
164 | .size = MTDPART_SIZ_FULL, |
165 | } }; |
166 | |
167 | static struct flash_platform_data flash = { |
168 | .name = "butterflash" , |
169 | .parts = partitions, |
170 | .nr_parts = ARRAY_SIZE(partitions), |
171 | }; |
172 | |
173 | /* REVISIT remove this ugly global and its "only one" limitation */ |
174 | static struct butterfly *butterfly; |
175 | |
176 | static void butterfly_attach(struct parport *p) |
177 | { |
178 | struct pardevice *pd; |
179 | int status; |
180 | struct butterfly *pp; |
181 | struct spi_controller *host; |
182 | struct device *dev = p->physport->dev; |
183 | struct pardev_cb butterfly_cb; |
184 | |
185 | if (butterfly || !dev) |
186 | return; |
187 | |
188 | /* REVISIT: this just _assumes_ a butterfly is there ... no probe, |
189 | * and no way to be selective about what it binds to. |
190 | */ |
191 | |
192 | host = spi_alloc_host(dev, size: sizeof(*pp)); |
193 | if (!host) { |
194 | status = -ENOMEM; |
195 | goto done; |
196 | } |
197 | pp = spi_controller_get_devdata(ctlr: host); |
198 | |
199 | /* |
200 | * SPI and bitbang hookup |
201 | * |
202 | * use default setup(), cleanup(), and transfer() methods; and |
203 | * only bother implementing mode 0. Start it later. |
204 | */ |
205 | host->bus_num = 42; |
206 | host->num_chipselect = 2; |
207 | |
208 | pp->bitbang.ctlr = host; |
209 | pp->bitbang.chipselect = butterfly_chipselect; |
210 | pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0; |
211 | |
212 | /* |
213 | * parport hookup |
214 | */ |
215 | pp->port = p; |
216 | memset(&butterfly_cb, 0, sizeof(butterfly_cb)); |
217 | butterfly_cb.private = pp; |
218 | pd = parport_register_dev_model(port: p, name: "spi_butterfly" , par_dev_cb: &butterfly_cb, cnt: 0); |
219 | if (!pd) { |
220 | status = -ENOMEM; |
221 | goto clean0; |
222 | } |
223 | pp->pd = pd; |
224 | |
225 | status = parport_claim(dev: pd); |
226 | if (status < 0) |
227 | goto clean1; |
228 | |
229 | /* |
230 | * Butterfly reset, powerup, run firmware |
231 | */ |
232 | pr_debug("%s: powerup/reset Butterfly\n" , p->name); |
233 | |
234 | /* nCS for dataflash (this bit is inverted on output) */ |
235 | parport_frob_control(pp->port, spi_cs_bit, 0); |
236 | |
237 | /* stabilize power with chip in reset (nRESET), and |
238 | * spi_sck_bit clear (CPOL=0) |
239 | */ |
240 | pp->lastbyte |= vcc_bits; |
241 | parport_write_data(pp->port, pp->lastbyte); |
242 | msleep(msecs: 5); |
243 | |
244 | /* take it out of reset; assume long reset delay */ |
245 | pp->lastbyte |= butterfly_nreset; |
246 | parport_write_data(pp->port, pp->lastbyte); |
247 | msleep(msecs: 100); |
248 | |
249 | /* |
250 | * Start SPI ... for now, hide that we're two physical busses. |
251 | */ |
252 | status = spi_bitbang_start(spi: &pp->bitbang); |
253 | if (status < 0) |
254 | goto clean2; |
255 | |
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. |
259 | */ |
260 | |
261 | pp->info[0].max_speed_hz = 15 * 1000 * 1000; |
262 | strcpy(p: pp->info[0].modalias, q: "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.ctlr, &pp->info[0]); |
267 | if (pp->dataflash) |
268 | pr_debug("%s: dataflash at %s\n" , p->name, |
269 | dev_name(&pp->dataflash->dev)); |
270 | |
271 | pr_info("%s: AVR Butterfly\n" , p->name); |
272 | butterfly = pp; |
273 | return; |
274 | |
275 | clean2: |
276 | /* turn off VCC */ |
277 | parport_write_data(pp->port, 0); |
278 | |
279 | parport_release(dev: pp->pd); |
280 | clean1: |
281 | parport_unregister_device(dev: pd); |
282 | clean0: |
283 | spi_controller_put(ctlr: host); |
284 | done: |
285 | pr_debug("%s: butterfly probe, fail %d\n" , p->name, status); |
286 | } |
287 | |
288 | static void butterfly_detach(struct parport *p) |
289 | { |
290 | struct butterfly *pp; |
291 | |
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? |
295 | */ |
296 | if (!butterfly || butterfly->port != p) |
297 | return; |
298 | pp = butterfly; |
299 | butterfly = NULL; |
300 | |
301 | /* stop() unregisters child devices too */ |
302 | spi_bitbang_stop(spi: &pp->bitbang); |
303 | |
304 | /* turn off VCC */ |
305 | parport_write_data(pp->port, 0); |
306 | msleep(msecs: 10); |
307 | |
308 | parport_release(dev: pp->pd); |
309 | parport_unregister_device(dev: pp->pd); |
310 | |
311 | spi_controller_put(ctlr: pp->bitbang.ctlr); |
312 | } |
313 | |
314 | static struct parport_driver butterfly_driver = { |
315 | .name = "spi_butterfly" , |
316 | .match_port = butterfly_attach, |
317 | .detach = butterfly_detach, |
318 | .devmodel = true, |
319 | }; |
320 | module_parport_driver(butterfly_driver); |
321 | |
322 | MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly" ); |
323 | MODULE_LICENSE("GPL" ); |
324 | |