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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * parport-to-butterfly adapter4 *5 * Copyright (C) 2005 David Brownell6 */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 card23 * with a battery powered AVR microcontroller and lots of goodies. You24 * can use GCC to develop firmware for this.25 *26 * See Documentation/spi/butterfly.rst for information about how to build27 * 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 44static inline struct butterfly *spidev_to_pp(struct spi_device *spi)45{46 return spi->controller_data;47}48 49struct 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 66static inline void67setsck(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 else77 byte &= ~bit;78 parport_write_data(pp->port, byte);79 pp->lastbyte = byte;80}81 82static inline void83setmosi(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 else93 byte &= ~bit;94 parport_write_data(pp->port, byte);95 pp->lastbyte = byte;96}97 98static 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 111static 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, spi->mode & SPI_CPOL);118 119 /* here, value == "activate or not";120 * most PARPORT_CONTROL_* bits are negated, so we must121 * 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 136static u32137butterfly_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, 0, flags, word, bits);141}142 143/*----------------------------------------------------------------------*/144 145/* override default partitioning with cmdlinepart */146static 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/page153 */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/page160 * sectors 3-5 = 512 pages * 264 bytes/page161 */162 .name = "filesystem", /* 462 KB */163 .offset = MTDPART_OFS_APPEND,164 .size = MTDPART_SIZ_FULL,165} };166 167static 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 */174static struct butterfly *butterfly;175 176static 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, sizeof(*pp));193 if (!host) {194 status = -ENOMEM;195 goto done;196 }197 pp = spi_controller_get_devdata(host);198 199 /*200 * SPI and bitbang hookup201 *202 * use default setup(), cleanup(), and transfer() methods; and203 * 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 hookup214 */215 pp->port = p;216 memset(&butterfly_cb, 0, sizeof(butterfly_cb));217 butterfly_cb.private = pp;218 pd = parport_register_dev_model(p, "spi_butterfly", &butterfly_cb, 0);219 if (!pd) {220 status = -ENOMEM;221 goto clean0;222 }223 pp->pd = pd;224 225 status = parport_claim(pd);226 if (status < 0)227 goto clean1;228 229 /*230 * Butterfly reset, powerup, run firmware231 */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), and238 * spi_sck_bit clear (CPOL=0)239 */240 pp->lastbyte |= vcc_bits;241 parport_write_data(pp->port, pp->lastbyte);242 msleep(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(100);248 249 /*250 * Start SPI ... for now, hide that we're two physical busses.251 */252 status = spi_bitbang_start(&pp->bitbang);253 if (status < 0)254 goto clean2;255 256 /* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR257 * (firmware resets at45, acts as spi slave) or neither (we ignore258 * 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(pp->info[0].modalias, "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 275clean2:276 /* turn off VCC */277 parport_write_data(pp->port, 0);278 279 parport_release(pp->pd);280clean1:281 parport_unregister_device(pd);282clean0:283 spi_controller_put(host);284done:285 pr_debug("%s: butterfly probe, fail %d\n", p->name, status);286}287 288static void butterfly_detach(struct parport *p)289{290 struct butterfly *pp;291 292 /* FIXME this global is ugly ... but, how to quickly get from293 * 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(&pp->bitbang);303 304 /* turn off VCC */305 parport_write_data(pp->port, 0);306 msleep(10);307 308 parport_release(pp->pd);309 parport_unregister_device(pp->pd);310 311 spi_controller_put(pp->bitbang.ctlr);312}313 314static struct parport_driver butterfly_driver = {315 .name = "spi_butterfly",316 .match_port = butterfly_attach,317 .detach = butterfly_detach,318};319module_parport_driver(butterfly_driver);320 321MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");322MODULE_LICENSE("GPL");323