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 * 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/module.h> 24 #include <linux/device.h> 25 #include <linux/parport.h> 26 27 #include <linux/sched.h> 28 #include <linux/spi/spi.h> 29 #include <linux/spi/spi_bitbang.h> 30 #include <linux/spi/flash.h> 31 32 #include <linux/mtd/partitions.h> 33 34 35 /* 36 * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card 37 * with a battery powered AVR microcontroller and lots of goodies. You 38 * can use GCC to develop firmware for this. 39 * 40 * See Documentation/spi/butterfly for information about how to build 41 * and use this custom parallel port cable. 42 */ 43 44 45 /* DATA output bits (pins 2..9 == D0..D7) */ 46 #define butterfly_nreset (1 << 1) /* pin 3 */ 47 48 #define spi_sck_bit (1 << 0) /* pin 2 */ 49 #define spi_mosi_bit (1 << 7) /* pin 9 */ 50 51 #define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */ 52 53 /* STATUS input bits */ 54 #define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */ 55 56 /* CONTROL output bits */ 57 #define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */ 58 59 60 61 static inline struct butterfly *spidev_to_pp(struct spi_device *spi) 62 { 63 return spi->controller_data; 64 } 65 66 67 struct butterfly { 68 /* REVISIT ... for now, this must be first */ 69 struct spi_bitbang bitbang; 70 71 struct parport *port; 72 struct pardevice *pd; 73 74 u8 lastbyte; 75 76 struct spi_device *dataflash; 77 struct spi_device *butterfly; 78 struct spi_board_info info[2]; 79 80 }; 81 82 /*----------------------------------------------------------------------*/ 83 84 static inline void 85 setsck(struct spi_device *spi, int is_on) 86 { 87 struct butterfly *pp = spidev_to_pp(spi); 88 u8 bit, byte = pp->lastbyte; 89 90 bit = spi_sck_bit; 91 92 if (is_on) 93 byte |= bit; 94 else 95 byte &= ~bit; 96 parport_write_data(pp->port, byte); 97 pp->lastbyte = byte; 98 } 99 100 static inline void 101 setmosi(struct spi_device *spi, int is_on) 102 { 103 struct butterfly *pp = spidev_to_pp(spi); 104 u8 bit, byte = pp->lastbyte; 105 106 bit = spi_mosi_bit; 107 108 if (is_on) 109 byte |= bit; 110 else 111 byte &= ~bit; 112 parport_write_data(pp->port, byte); 113 pp->lastbyte = byte; 114 } 115 116 static inline int getmiso(struct spi_device *spi) 117 { 118 struct butterfly *pp = spidev_to_pp(spi); 119 int value; 120 u8 bit; 121 122 bit = spi_miso_bit; 123 124 /* only STATUS_BUSY is NOT negated */ 125 value = !(parport_read_status(pp->port) & bit); 126 return (bit == PARPORT_STATUS_BUSY) ? value : !value; 127 } 128 129 static void butterfly_chipselect(struct spi_device *spi, int value) 130 { 131 struct butterfly *pp = spidev_to_pp(spi); 132 133 /* set default clock polarity */ 134 if (value != BITBANG_CS_INACTIVE) 135 setsck(spi, spi->mode & SPI_CPOL); 136 137 /* here, value == "activate or not"; 138 * most PARPORT_CONTROL_* bits are negated, so we must 139 * morph it to value == "bit value to write in control register" 140 */ 141 if (spi_cs_bit == PARPORT_CONTROL_INIT) 142 value = !value; 143 144 parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0); 145 } 146 147 148 /* we only needed to implement one mode here, and choose SPI_MODE_0 */ 149 150 #define spidelay(X) do { } while (0) 151 /* #define spidelay ndelay */ 152 153 #include "spi-bitbang-txrx.h" 154 155 static u32 156 butterfly_txrx_word_mode0(struct spi_device *spi, 157 unsigned nsecs, 158 u32 word, u8 bits) 159 { 160 return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits); 161 } 162 163 /*----------------------------------------------------------------------*/ 164 165 /* override default partitioning with cmdlinepart */ 166 static struct mtd_partition partitions[] = { { 167 /* JFFS2 wants partitions of 4*N blocks for this device, 168 * so sectors 0 and 1 can't be partitions by themselves. 169 */ 170 171 /* sector 0 = 8 pages * 264 bytes/page (1 block) 172 * sector 1 = 248 pages * 264 bytes/page 173 */ 174 .name = "bookkeeping", /* 66 KB */ 175 .offset = 0, 176 .size = (8 + 248) * 264, 177 /* .mask_flags = MTD_WRITEABLE, */ 178 }, { 179 /* sector 2 = 256 pages * 264 bytes/page 180 * sectors 3-5 = 512 pages * 264 bytes/page 181 */ 182 .name = "filesystem", /* 462 KB */ 183 .offset = MTDPART_OFS_APPEND, 184 .size = MTDPART_SIZ_FULL, 185 } }; 186 187 static struct flash_platform_data flash = { 188 .name = "butterflash", 189 .parts = partitions, 190 .nr_parts = ARRAY_SIZE(partitions), 191 }; 192 193 194 /* REVISIT remove this ugly global and its "only one" limitation */ 195 static struct butterfly *butterfly; 196 197 static void butterfly_attach(struct parport *p) 198 { 199 struct pardevice *pd; 200 int status; 201 struct butterfly *pp; 202 struct spi_master *master; 203 struct device *dev = p->physport->dev; 204 205 if (butterfly || !dev) 206 return; 207 208 /* REVISIT: this just _assumes_ a butterfly is there ... no probe, 209 * and no way to be selective about what it binds to. 210 */ 211 212 master = spi_alloc_master(dev, sizeof(*pp)); 213 if (!master) { 214 status = -ENOMEM; 215 goto done; 216 } 217 pp = spi_master_get_devdata(master); 218 219 /* 220 * SPI and bitbang hookup 221 * 222 * use default setup(), cleanup(), and transfer() methods; and 223 * only bother implementing mode 0. Start it later. 224 */ 225 master->bus_num = 42; 226 master->num_chipselect = 2; 227 228 pp->bitbang.master = master; 229 pp->bitbang.chipselect = butterfly_chipselect; 230 pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0; 231 232 /* 233 * parport hookup 234 */ 235 pp->port = p; 236 pd = parport_register_device(p, "spi_butterfly", 237 NULL, NULL, NULL, 238 0 /* FLAGS */, pp); 239 if (!pd) { 240 status = -ENOMEM; 241 goto clean0; 242 } 243 pp->pd = pd; 244 245 status = parport_claim(pd); 246 if (status < 0) 247 goto clean1; 248 249 /* 250 * Butterfly reset, powerup, run firmware 251 */ 252 pr_debug("%s: powerup/reset Butterfly\n", p->name); 253 254 /* nCS for dataflash (this bit is inverted on output) */ 255 parport_frob_control(pp->port, spi_cs_bit, 0); 256 257 /* stabilize power with chip in reset (nRESET), and 258 * spi_sck_bit clear (CPOL=0) 259 */ 260 pp->lastbyte |= vcc_bits; 261 parport_write_data(pp->port, pp->lastbyte); 262 msleep(5); 263 264 /* take it out of reset; assume long reset delay */ 265 pp->lastbyte |= butterfly_nreset; 266 parport_write_data(pp->port, pp->lastbyte); 267 msleep(100); 268 269 270 /* 271 * Start SPI ... for now, hide that we're two physical busses. 272 */ 273 status = spi_bitbang_start(&pp->bitbang); 274 if (status < 0) 275 goto clean2; 276 277 /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR 278 * (firmware resets at45, acts as spi slave) or neither (we ignore 279 * both, AVR uses AT45). Here we expect firmware for the first option. 280 */ 281 282 pp->info[0].max_speed_hz = 15 * 1000 * 1000; 283 strcpy(pp->info[0].modalias, "mtd_dataflash"); 284 pp->info[0].platform_data = &flash; 285 pp->info[0].chip_select = 1; 286 pp->info[0].controller_data = pp; 287 pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]); 288 if (pp->dataflash) 289 pr_debug("%s: dataflash at %s\n", p->name, 290 dev_name(&pp->dataflash->dev)); 291 292 pr_info("%s: AVR Butterfly\n", p->name); 293 butterfly = pp; 294 return; 295 296 clean2: 297 /* turn off VCC */ 298 parport_write_data(pp->port, 0); 299 300 parport_release(pp->pd); 301 clean1: 302 parport_unregister_device(pd); 303 clean0: 304 (void) spi_master_put(pp->bitbang.master); 305 done: 306 pr_debug("%s: butterfly probe, fail %d\n", p->name, status); 307 } 308 309 static void butterfly_detach(struct parport *p) 310 { 311 struct butterfly *pp; 312 int status; 313 314 /* FIXME this global is ugly ... but, how to quickly get from 315 * the parport to the "struct butterfly" associated with it? 316 * "old school" driver-internal device lists? 317 */ 318 if (!butterfly || butterfly->port != p) 319 return; 320 pp = butterfly; 321 butterfly = NULL; 322 323 /* stop() unregisters child devices too */ 324 status = spi_bitbang_stop(&pp->bitbang); 325 326 /* turn off VCC */ 327 parport_write_data(pp->port, 0); 328 msleep(10); 329 330 parport_release(pp->pd); 331 parport_unregister_device(pp->pd); 332 333 (void) spi_master_put(pp->bitbang.master); 334 } 335 336 static struct parport_driver butterfly_driver = { 337 .name = "spi_butterfly", 338 .attach = butterfly_attach, 339 .detach = butterfly_detach, 340 }; 341 342 343 static int __init butterfly_init(void) 344 { 345 return parport_register_driver(&butterfly_driver); 346 } 347 device_initcall(butterfly_init); 348 349 static void __exit butterfly_exit(void) 350 { 351 parport_unregister_driver(&butterfly_driver); 352 } 353 module_exit(butterfly_exit); 354 355 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly"); 356 MODULE_LICENSE("GPL"); 357