358 lines
8.5 KiB
C
358 lines
8.5 KiB
C
/*
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* parport-to-butterfly adapter
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*
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* Copyright (C) 2005 David Brownell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/parport.h>
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#include <linux/sched.h>
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#include <linux/spi/spi.h>
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#include <linux/spi/spi_bitbang.h>
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#include <linux/spi/flash.h>
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#include <linux/mtd/partitions.h>
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/*
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* This uses SPI to talk with an "AVR Butterfly", which is a $US20 card
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* with a battery powered AVR microcontroller and lots of goodies. You
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* can use GCC to develop firmware for this.
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*
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* See Documentation/spi/butterfly for information about how to build
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* and use this custom parallel port cable.
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*/
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/* DATA output bits (pins 2..9 == D0..D7) */
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#define butterfly_nreset (1 << 1) /* pin 3 */
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#define spi_sck_bit (1 << 0) /* pin 2 */
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#define spi_mosi_bit (1 << 7) /* pin 9 */
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#define vcc_bits ((1 << 6) | (1 << 5)) /* pins 7, 8 */
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/* STATUS input bits */
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#define spi_miso_bit PARPORT_STATUS_BUSY /* pin 11 */
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/* CONTROL output bits */
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#define spi_cs_bit PARPORT_CONTROL_SELECT /* pin 17 */
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static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
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{
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return spi->controller_data;
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}
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struct butterfly {
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/* REVISIT ... for now, this must be first */
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struct spi_bitbang bitbang;
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struct parport *port;
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struct pardevice *pd;
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u8 lastbyte;
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struct spi_device *dataflash;
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struct spi_device *butterfly;
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struct spi_board_info info[2];
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};
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/*----------------------------------------------------------------------*/
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static inline void
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setsck(struct spi_device *spi, int is_on)
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{
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struct butterfly *pp = spidev_to_pp(spi);
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u8 bit, byte = pp->lastbyte;
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bit = spi_sck_bit;
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if (is_on)
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byte |= bit;
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else
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byte &= ~bit;
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parport_write_data(pp->port, byte);
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pp->lastbyte = byte;
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}
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static inline void
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setmosi(struct spi_device *spi, int is_on)
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{
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struct butterfly *pp = spidev_to_pp(spi);
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u8 bit, byte = pp->lastbyte;
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bit = spi_mosi_bit;
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if (is_on)
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byte |= bit;
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else
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byte &= ~bit;
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parport_write_data(pp->port, byte);
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pp->lastbyte = byte;
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}
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static inline int getmiso(struct spi_device *spi)
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{
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struct butterfly *pp = spidev_to_pp(spi);
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int value;
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u8 bit;
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bit = spi_miso_bit;
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/* only STATUS_BUSY is NOT negated */
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value = !(parport_read_status(pp->port) & bit);
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return (bit == PARPORT_STATUS_BUSY) ? value : !value;
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}
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static void butterfly_chipselect(struct spi_device *spi, int value)
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{
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struct butterfly *pp = spidev_to_pp(spi);
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/* set default clock polarity */
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if (value != BITBANG_CS_INACTIVE)
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setsck(spi, spi->mode & SPI_CPOL);
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/* here, value == "activate or not";
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* most PARPORT_CONTROL_* bits are negated, so we must
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* morph it to value == "bit value to write in control register"
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*/
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if (spi_cs_bit == PARPORT_CONTROL_INIT)
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value = !value;
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parport_frob_control(pp->port, spi_cs_bit, value ? spi_cs_bit : 0);
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}
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/* we only needed to implement one mode here, and choose SPI_MODE_0 */
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#define spidelay(X) do{}while(0)
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//#define spidelay ndelay
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#include "spi-bitbang-txrx.h"
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static u32
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butterfly_txrx_word_mode0(struct spi_device *spi,
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unsigned nsecs,
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u32 word, u8 bits)
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{
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return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
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}
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/*----------------------------------------------------------------------*/
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/* override default partitioning with cmdlinepart */
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static struct mtd_partition partitions[] = { {
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/* JFFS2 wants partitions of 4*N blocks for this device,
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* so sectors 0 and 1 can't be partitions by themselves.
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*/
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/* sector 0 = 8 pages * 264 bytes/page (1 block)
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* sector 1 = 248 pages * 264 bytes/page
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*/
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.name = "bookkeeping", // 66 KB
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.offset = 0,
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.size = (8 + 248) * 264,
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// .mask_flags = MTD_WRITEABLE,
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}, {
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/* sector 2 = 256 pages * 264 bytes/page
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* sectors 3-5 = 512 pages * 264 bytes/page
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*/
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.name = "filesystem", // 462 KB
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.offset = MTDPART_OFS_APPEND,
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.size = MTDPART_SIZ_FULL,
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} };
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static struct flash_platform_data flash = {
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.name = "butterflash",
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.parts = partitions,
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.nr_parts = ARRAY_SIZE(partitions),
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};
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/* REVISIT remove this ugly global and its "only one" limitation */
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static struct butterfly *butterfly;
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static void butterfly_attach(struct parport *p)
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{
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struct pardevice *pd;
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int status;
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struct butterfly *pp;
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struct spi_master *master;
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struct device *dev = p->physport->dev;
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if (butterfly || !dev)
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return;
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/* REVISIT: this just _assumes_ a butterfly is there ... no probe,
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* and no way to be selective about what it binds to.
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*/
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master = spi_alloc_master(dev, sizeof *pp);
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if (!master) {
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status = -ENOMEM;
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goto done;
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}
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pp = spi_master_get_devdata(master);
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/*
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* SPI and bitbang hookup
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*
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* use default setup(), cleanup(), and transfer() methods; and
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* only bother implementing mode 0. Start it later.
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*/
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master->bus_num = 42;
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master->num_chipselect = 2;
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pp->bitbang.master = spi_master_get(master);
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pp->bitbang.chipselect = butterfly_chipselect;
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pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
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/*
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* parport hookup
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*/
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pp->port = p;
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pd = parport_register_device(p, "spi_butterfly",
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NULL, NULL, NULL,
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0 /* FLAGS */, pp);
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if (!pd) {
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status = -ENOMEM;
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goto clean0;
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}
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pp->pd = pd;
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status = parport_claim(pd);
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if (status < 0)
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goto clean1;
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/*
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* Butterfly reset, powerup, run firmware
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*/
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pr_debug("%s: powerup/reset Butterfly\n", p->name);
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/* nCS for dataflash (this bit is inverted on output) */
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parport_frob_control(pp->port, spi_cs_bit, 0);
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/* stabilize power with chip in reset (nRESET), and
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* spi_sck_bit clear (CPOL=0)
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*/
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pp->lastbyte |= vcc_bits;
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parport_write_data(pp->port, pp->lastbyte);
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msleep(5);
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/* take it out of reset; assume long reset delay */
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pp->lastbyte |= butterfly_nreset;
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parport_write_data(pp->port, pp->lastbyte);
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msleep(100);
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/*
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* Start SPI ... for now, hide that we're two physical busses.
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*/
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status = spi_bitbang_start(&pp->bitbang);
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if (status < 0)
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goto clean2;
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/* Bus 1 lets us talk to at45db041b (firmware disables AVR SPI), AVR
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* (firmware resets at45, acts as spi slave) or neither (we ignore
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* both, AVR uses AT45). Here we expect firmware for the first option.
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*/
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pp->info[0].max_speed_hz = 15 * 1000 * 1000;
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strcpy(pp->info[0].modalias, "mtd_dataflash");
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pp->info[0].platform_data = &flash;
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pp->info[0].chip_select = 1;
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pp->info[0].controller_data = pp;
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pp->dataflash = spi_new_device(pp->bitbang.master, &pp->info[0]);
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if (pp->dataflash)
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pr_debug("%s: dataflash at %s\n", p->name,
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dev_name(&pp->dataflash->dev));
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// dev_info(_what?_, ...)
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pr_info("%s: AVR Butterfly\n", p->name);
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butterfly = pp;
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return;
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clean2:
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/* turn off VCC */
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parport_write_data(pp->port, 0);
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parport_release(pp->pd);
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clean1:
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parport_unregister_device(pd);
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clean0:
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(void) spi_master_put(pp->bitbang.master);
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done:
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pr_debug("%s: butterfly probe, fail %d\n", p->name, status);
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}
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static void butterfly_detach(struct parport *p)
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{
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struct butterfly *pp;
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int status;
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/* FIXME this global is ugly ... but, how to quickly get from
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* the parport to the "struct butterfly" associated with it?
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* "old school" driver-internal device lists?
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*/
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if (!butterfly || butterfly->port != p)
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return;
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pp = butterfly;
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butterfly = NULL;
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/* stop() unregisters child devices too */
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status = spi_bitbang_stop(&pp->bitbang);
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/* turn off VCC */
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parport_write_data(pp->port, 0);
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msleep(10);
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parport_release(pp->pd);
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parport_unregister_device(pp->pd);
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(void) spi_master_put(pp->bitbang.master);
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}
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static struct parport_driver butterfly_driver = {
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.name = "spi_butterfly",
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.attach = butterfly_attach,
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.detach = butterfly_detach,
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};
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static int __init butterfly_init(void)
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{
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return parport_register_driver(&butterfly_driver);
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}
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device_initcall(butterfly_init);
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static void __exit butterfly_exit(void)
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{
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parport_unregister_driver(&butterfly_driver);
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}
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module_exit(butterfly_exit);
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MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
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MODULE_LICENSE("GPL");
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