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/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 60 static inline struct butterfly *spidev_to_pp(struct spi_device *spi) 61 { 62 return spi->controller_data; 63 } 64 65 66 struct 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 83 static inline void 84 setsck(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 99 static inline void 100 setmosi(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 } 114 115 static 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 } 127 128 static 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" 153 154 static u32 155 butterfly_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 */ 165 static 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 } }; 185 186 static 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 */ 194 static struct butterfly *butterfly; 195 196 static 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; 295 296 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