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