diff options
| -rw-r--r-- | Documentation/spi/butterfly | 57 | ||||
| -rw-r--r-- | drivers/spi/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/spi/spi_butterfly.c | 423 |
3 files changed, 490 insertions, 0 deletions
diff --git a/Documentation/spi/butterfly b/Documentation/spi/butterfly new file mode 100644 index 0000000..a2e8c8d --- /dev/null +++ b/Documentation/spi/butterfly @@ -0,0 +1,57 @@ +spi_butterfly - parport-to-butterfly adapter driver +=================================================== + +This is a hardware and software project that includes building and using +a parallel port adapter cable, together with an "AVR Butterfly" to run +firmware for user interfacing and/or sensors. A Butterfly is a $US20 +battery powered card with an AVR microcontroller and lots of goodies: +sensors, LCD, flash, toggle stick, and more. You can use AVR-GCC to +develop firmware for this, and flash it using this adapter cable. + +You can make this adapter from an old printer cable and solder things +directly to the Butterfly. Or (if you have the parts and skills) you +can come up with something fancier, providing ciruit protection to the +Butterfly and the printer port, or with a better power supply than two +signal pins from the printer port. + + +The first cable connections will hook Linux up to one SPI bus, with the +AVR and a DataFlash chip; and to the AVR reset line. This is all you +need to reflash the firmware, and the pins are the standard Atmel "ISP" +connector pins (used also on non-Butterfly AVR boards). + + Signal Butterfly Parport (DB-25) + ------ --------- --------------- + SCK = J403.PB1/SCK = pin 2/D0 + RESET = J403.nRST = pin 3/D1 + VCC = J403.VCC_EXT = pin 8/D6 + MOSI = J403.PB2/MOSI = pin 9/D7 + MISO = J403.PB3/MISO = pin 11/S7,nBUSY + GND = J403.GND = pin 23/GND + +Then to let Linux master that bus to talk to the DataFlash chip, you must +(a) flash new firmware that disables SPI (set PRR.2, and disable pullups +by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and +(c) cable in the chipselect. + + Signal Butterfly Parport (DB-25) + ------ --------- --------------- + VCC = J400.VCC_EXT = pin 7/D5 + SELECT = J400.PB0/nSS = pin 17/C3,nSELECT + GND = J400.GND = pin 24/GND + +The "USI" controller, using J405, can be used for a second SPI bus. That +would let you talk to the AVR over SPI, running firmware that makes it act +as an SPI slave, while letting either Linux or the AVR use the DataFlash. +There are plenty of spare parport pins to wire this one up, such as: + + Signal Butterfly Parport (DB-25) + ------ --------- --------------- + SCK = J403.PE4/USCK = pin 5/D3 + MOSI = J403.PE5/DI = pin 6/D4 + MISO = J403.PE6/DO = pin 12/S5,nPAPEROUT + GND = J403.GND = pin 22/GND + + IRQ = J402.PF4 = pin 10/S6,ACK + GND = J402.GND(P2) = pin 25/GND + diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index 7a75fae..b77dbd6 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -75,6 +75,16 @@ config SPI_BUTTERFLY inexpensive battery powered microcontroller evaluation board. This same cable can be used to flash new firmware. +config SPI_BUTTERFLY + tristate "Parallel port adapter for AVR Butterfly (DEVELOPMENT)" + depends on SPI_MASTER && PARPORT && EXPERIMENTAL + select SPI_BITBANG + help + This uses a custom parallel port cable to connect to an AVR + Butterfly <http://www.atmel.com/products/avr/butterfly>, an + inexpensive battery powered microcontroller evaluation board. + This same cable can be used to flash new firmware. + # # Add new SPI master controllers in alphabetical order above this line # diff --git a/drivers/spi/spi_butterfly.c b/drivers/spi/spi_butterfly.c new file mode 100644 index 0000000..79a3c59 --- /dev/null +++ b/drivers/spi/spi_butterfly.c @@ -0,0 +1,423 @@ +/* + * spi_butterfly.c - parport-to-butterfly adapter + * + * Copyright (C) 2005 David Brownell + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/platform_device.h> +#include <linux/parport.h> + +#include <linux/spi/spi.h> +#include <linux/spi/spi_bitbang.h> +#include <linux/spi/flash.h> + +#include <linux/mtd/partitions.h> + + +/* + * This uses SPI to talk with an "AVR Butterfly", which is a $US20 card + * with a battery powered AVR microcontroller and lots of goodies. You + * can use GCC to develop firmware for this. + * + * See Documentation/spi/butterfly for information about how to build + * and use this custom parallel port cable. + */ + +#undef HAVE_USI /* nyet */ + + +/* DATA output bits (pins 2..9 == D0..D7) */ +#define butterfly_nreset (1 << 1) /* pin 3 */ + +#define spi_sck_bit (1 << 0) /* pin 2 */ +#define spi_mosi_bit (1 << 7) /* pin 9 */ + +#define usi_sck_bit (1 << 3) /* pin 5 */ +#define usi_mosi_bit (1 << 4) /* pin 6 */ + +#define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */ + +/* STATUS input bits */ +#define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */ + +#define usi_miso_bit PARPORT_STATUS_PAPEROUT /* pin 12 */ + +/* CONTROL output bits */ +#define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */ +/* USI uses no chipselect */ + + + +static inline struct butterfly *spidev_to_pp(struct spi_device *spi) +{ + return spi->controller_data; +} + +static inline int is_usidev(struct spi_device *spi) +{ +#ifdef HAVE_USI + return spi->chip_select != 1; +#else + return 0; +#endif +} + + +struct butterfly { + /* REVISIT ... for now, this must be first */ + struct spi_bitbang bitbang; + + struct parport *port; + struct pardevice *pd; + + u8 lastbyte; + + struct spi_device *dataflash; + struct spi_device *butterfly; + struct spi_board_info info[2]; + +}; + +/*----------------------------------------------------------------------*/ + +/* + * these routines may be slower than necessary because they're hiding + * the fact that there are two different SPI busses on this cable: one + * to the DataFlash chip (or AVR SPI controller), the other to the + * AVR USI controller. + */ + +static inline void +setsck(struct spi_device *spi, int is_on) +{ + struct butterfly *pp = spidev_to_pp(spi); + u8 bit, byte = pp->lastbyte; + + if (is_usidev(spi)) + bit = usi_sck_bit; + else + bit = spi_sck_bit; + + if (is_on) + byte |= bit; + else + byte &= ~bit; + parport_write_data(pp->port, byte); + pp->lastbyte = byte; +} + +static inline void +setmosi(struct spi_device *spi, int is_on) +{ + struct butterfly *pp = spidev_to_pp(spi); + u8 bit, byte = pp->lastbyte; + + if (is_usidev(spi)) + bit = usi_mosi_bit; + else + bit = spi_mosi_bit; + + if (is_on) + byte |= bit; + else + byte &= ~bit; + parport_write_data(pp->port, byte); + pp->lastbyte = byte; +} + +static inline int getmiso(struct spi_device *spi) +{ + struct butterfly *pp = spidev_to_pp(spi); + int value; + u8 bit; + + if (is_usidev(spi)) + bit = usi_miso_bit; + else + bit = spi_miso_bit; + + /* only STATUS_BUSY is NOT negated */ + value = !(parport_read_status(pp->port) & bit); + return (bit == PARPORT_STATUS_BUSY) ? value : !value; +} + +static void butterfly_chipselect(struct spi_device *spi, int value) +{ + struct butterfly *pp = spidev_to_pp(spi); + + /* set default clock polarity */ + if (value) + setsck(spi, spi->mode & SPI_CPOL); + + /* no chipselect on this USI link config */ + if (is_usidev(spi)) + return; + + /* here, value == "activate or not" */ + + /* most PARPORT_CONTROL_* bits are negated */ + if (spi_cs_bit == PARPORT_CONTROL_INIT) + value = !value; + + /* here, value == "bit value to write in control register" */ + + parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0); +} + + +/* we only needed to implement one mode here, and choose SPI_MODE_0 */ + +#define spidelay(X) do{}while(0) +//#define spidelay ndelay + +#define EXPAND_BITBANG_TXRX +#include <linux/spi/spi_bitbang.h> + +static u32 +butterfly_txrx_word_mode0(struct spi_device *spi, + unsigned nsecs, + u32 word, u8 bits) +{ + return bitbang_txrx_be_cpha0(spi, nsecs, 0, word, bits); +} + +/*----------------------------------------------------------------------*/ + +/* override default partitioning with cmdlinepart */ +static struct mtd_partition partitions[] = { { + /* JFFS2 wants partitions of 4*N blocks for this device ... */ + + /* sector 0 = 8 pages * 264 bytes/page (1 block) + * sector 1 = 248 pages * 264 bytes/page + */ + .name = "bookkeeping", // 66 KB + .offset = 0, + .size = (8 + 248) * 264, +// .mask_flags = MTD_WRITEABLE, +}, { + /* sector 2 = 256 pages * 264 bytes/page + * sectors 3-5 = 512 pages * 264 bytes/page + */ + .name = "filesystem", // 462 KB + .offset = MTDPART_OFS_APPEND, + .size = MTDPART_SIZ_FULL, +} }; + +static struct flash_platform_data flash = { + .name = "butterflash", + .parts = partitions, + .nr_parts = ARRAY_SIZE(partitions), +}; + + +/* REVISIT remove this ugly global and its "only one" limitation */ +static struct butterfly *butterfly; + +static void butterfly_attach(struct parport *p) +{ + struct pardevice *pd; + int status; + struct butterfly *pp; + struct spi_master *master; + struct platform_device *pdev; + + if (butterfly) + return; + + /* REVISIT: this just _assumes_ a butterfly is there ... no probe, + * and no way to be selective about what it binds to. + */ + + /* FIXME where should master->cdev.dev come from? + * e.g. /sys/bus/pnp0/00:0b, some PCI thing, etc + * setting up a platform device like this is an ugly kluge... + */ + pdev = platform_device_register_simple("butterfly", -1, NULL, 0); + + master = spi_alloc_master(&pdev->dev, sizeof *pp); + if (!master) { + status = -ENOMEM; + goto done; + } + pp = spi_master_get_devdata(master); + + /* + * SPI and bitbang hookup + * + * use default setup(), cleanup(), and transfer() methods; and + * only bother implementing mode 0. Start it later. + */ + master->bus_num = 42; + master->num_chipselect = 2; + + pp->bitbang.master = spi_master_get(master); + pp->bitbang.chipselect = butterfly_chipselect; + pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0; + + /* + * parport hookup + */ + pp->port = p; + pd = parport_register_device(p, "spi_butterfly", + NULL, NULL, NULL, + 0 /* FLAGS */, pp); + if (!pd) { + status = -ENOMEM; + goto clean0; + } + pp->pd = pd; + + status = parport_claim(pd); + if (status < 0) + goto clean1; + + /* + * Butterfly reset, powerup, run firmware + */ + pr_debug("%s: powerup/reset Butterfly\n", p->name); + + /* nCS for dataflash (this bit is inverted on output) */ + parport_frob_control(pp->port, spi_cs_bit, 0); + + /* stabilize power with chip in reset (nRESET), and + * both spi_sck_bit and usi_sck_bit clear (CPOL=0) + */ + pp->lastbyte |= vcc_bits; + parport_write_data(pp->port, pp->lastbyte); + msleep(5); + + /* take it out of reset; assume long reset delay */ + pp->lastbyte |= butterfly_nreset; + parport_write_data(pp->port, pp->lastbyte); + msleep(100); + + + /* + * Start SPI ... for now, hide that we're two physical busses. + */ + status = spi_bitbang_start(&pp->bitbang); + if (status < 0) + goto clean2; + + /* Bus 1 lets us talk to at45db041b (firmware disables AVR) + * or AVR (firmware resets at45, acts as spi slave) + */ + pp->info[0].max_speed_hz = 15 * 1000 * 1000; + strcpy(pp->info[0].modalias, "mtd_dataflash"); + pp->info[0].platform_data = &flash; + pp->info[0].chip_select = 1; + pp->info[0].controller_data = pp; + pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]); + if (pp->dataflash) + pr_debug("%s: dataflash at %s\n", p->name, + pp->dataflash->dev.bus_id); + +#ifdef HAVE_USI + /* even more custom AVR firmware */ + pp->info[1].max_speed_hz = 10 /* ?? */ * 1000 * 1000; + strcpy(pp->info[1].modalias, "butterfly"); + // pp->info[1].platform_data = ... TBD ... ; + pp->info[1].chip_select = 2, + pp->info[1].controller_data = pp; + pp->butterfly = spi_new_device(pp->bitbang.master, &pp->info[1]); + if (pp->butterfly) + pr_debug("%s: butterfly at %s\n", p->name, + pp->butterfly->dev.bus_id); + + /* FIXME setup ACK for the IRQ line ... */ +#endif + + // dev_info(_what?_, ...) + pr_info("%s: AVR Butterfly\n", p->name); + butterfly = pp; + return; + +clean2: + /* turn off VCC */ + parport_write_data(pp->port, 0); + + parport_release(pp->pd); +clean1: + parport_unregister_device(pd); +clean0: + (void) spi_master_put(pp->bitbang.master); +done: + platform_device_unregister(pdev); + pr_debug("%s: butterfly probe, fail %d\n", p->name, status); +} + +static void butterfly_detach(struct parport *p) +{ + struct butterfly *pp; + struct platform_device *pdev; + int status; + + /* FIXME this global is ugly ... but, how to quickly get from + * the parport to the "struct butterfly" associated with it? + * "old school" driver-internal device lists? + */ + if (!butterfly || butterfly->port != p) + return; + pp = butterfly; + butterfly = NULL; + +#ifdef HAVE_USI + spi_unregister_device(pp->butterfly); + pp->butterfly = NULL; +#endif + spi_unregister_device(pp->dataflash); + pp->dataflash = NULL; + + status = spi_bitbang_stop(&pp->bitbang); + + /* turn off VCC */ + parport_write_data(pp->port, 0); + msleep(10); + + parport_release(pp->pd); + parport_unregister_device(pp->pd); + + pdev = to_platform_device(pp->bitbang.master->cdev.dev); + + (void) spi_master_put(pp->bitbang.master); + + platform_device_unregister(pdev); +} + +static struct parport_driver butterfly_driver = { + .name = "spi_butterfly", + .attach = butterfly_attach, + .detach = butterfly_detach, +}; + + +static int __init butterfly_init(void) +{ + return parport_register_driver(&butterfly_driver); +} +device_initcall(butterfly_init); + +static void __exit butterfly_exit(void) +{ + parport_unregister_driver(&butterfly_driver); +} +module_exit(butterfly_exit); + +MODULE_LICENSE("GPL"); |