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334 lines
7.9 KiB
334 lines
7.9 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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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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#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.rst 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, unsigned nsecs, u32 word, |
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u8 bits, unsigned flags) |
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{ |
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return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, 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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struct pardev_cb butterfly_cb; |
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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 = 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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memset(&butterfly_cb, 0, sizeof(butterfly_cb)); |
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butterfly_cb.private = pp; |
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pd = parport_register_dev_model(p, "spi_butterfly", &butterfly_cb, 0); |
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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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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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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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/* 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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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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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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.match_port = butterfly_attach, |
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.detach = butterfly_detach, |
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.devmodel = true, |
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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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