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 57 static inline struct butterfly *spidev_to_pp(struct spi_device *spi) 58 { 59 return spi->controller_data; 60 } 61 62 63 struct 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 80 static inline void 81 setsck(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 96 static inline void 97 setmosi(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 } 111 112 static 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 } 124 125 static 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" 150 151 static u32 152 butterfly_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 */ 162 static 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 } }; 182 183 static 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 */ 191 static struct butterfly *butterfly; 192 193 static 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; 291 292 clean2: 293 /* turn off VCC */ 294 parport_write_data(pp->port, 0); 295 296 parport_release(pp->pd); 297 clean1: 298 parport_unregister_device(pd); 299 clean0: 300 (void) spi_master_put(pp->bitbang.master); 301 done: 302 pr_debug("%s: butterfly probe, fail %d\n", p->name, status); 303 } 304 305 static 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 } 330 331 static struct parport_driver butterfly_driver = { 332 .name = "spi_butterfly", 333 .attach = butterfly_attach, 334 .detach = butterfly_detach, 335 }; 336 337 338 static int __init butterfly_init(void) 339 { 340 return parport_register_driver(&butterfly_driver); 341 } 342 device_initcall(butterfly_init); 343 344 static void __exit butterfly_exit(void) 345 { 346 parport_unregister_driver(&butterfly_driver); 347 } 348 module_exit(butterfly_exit); 349 350 MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly"); 351 MODULE_LICENSE("GPL"); 352