// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * parport-to-butterfly adapter

   *
   * Copyright (C) 2005 David Brownell

   */

  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/delay.h>

  #include <linux/module.h>

  #include <linux/device.h>

  #include <linux/parport.h>

  #include <linux/sched.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.rst for information about how to build

   * and use this custom parallel port cable.
   */

  /* 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	vcc_bits	((1 << 6) | (1 << 5))	/* pins 7, 8 */
  
  /* STATUS input bits */
  #define	spi_miso_bit	PARPORT_STATUS_BUSY	/* pin 11 */

  /* CONTROL output bits */
  #define	spi_cs_bit	PARPORT_CONTROL_SELECT	/* pin 17 */

  static inline struct butterfly *spidev_to_pp(struct spi_device *spi)
  {
  	return spi->controller_data;
  }

  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];
  
  };
  
  /*----------------------------------------------------------------------*/

  static inline void
  setsck(struct spi_device *spi, int is_on)
  {
  	struct butterfly	*pp = spidev_to_pp(spi);
  	u8			bit, byte = pp->lastbyte;

  	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;

  	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;

  	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 != BITBANG_CS_INACTIVE)

  		setsck(spi, spi->mode & SPI_CPOL);

  	/* here, value == "activate or not";
  	 * most PARPORT_CONTROL_* bits are negated, so we must
  	 * morph it to value == "bit value to write in control register"
  	 */

  	if (spi_cs_bit == PARPORT_CONTROL_INIT)
  		value = !value;

  	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 */

  #include "spi-bitbang-txrx.h"

  
  static u32

  butterfly_txrx_word_mode0(struct spi_device *spi, unsigned nsecs, u32 word,

  			  u8 bits, unsigned flags)

  {

  	return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);

  }
  
  /*----------------------------------------------------------------------*/
  
  /* override default partitioning with cmdlinepart */
  static struct mtd_partition partitions[] = { {

  	/* JFFS2 wants partitions of 4*N blocks for this device,
  	 * so sectors 0 and 1 can't be partitions by themselves.
  	 */

  
  	/* 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 device		*dev = p->physport->dev;

  	struct pardev_cb	butterfly_cb;

  	if (butterfly || !dev)

  		return;
  
  	/* REVISIT:  this just _assumes_ a butterfly is there ... no probe,
  	 * and no way to be selective about what it binds to.
  	 */

  	master = spi_alloc_master(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 = master;

  	pp->bitbang.chipselect = butterfly_chipselect;
  	pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
  
  	/*
  	 * parport hookup
  	 */
  	pp->port = p;

  	memset(&butterfly_cb, 0, sizeof(butterfly_cb));
  	butterfly_cb.private = pp;
  	pd = parport_register_dev_model(p, "spi_butterfly", &butterfly_cb, 0);

  	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
  ", 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

  	 * spi_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 SPI), AVR
  	 * (firmware resets at45, acts as spi slave) or neither (we ignore
  	 * both, AVR uses AT45).  Here we expect firmware for the first option.

  	 */

  	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
  ", p->name,

  			 dev_name(&pp->dataflash->dev));

  	pr_info("%s: AVR Butterfly
  ", 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:

  	spi_master_put(pp->bitbang.master);

  done:

  	pr_debug("%s: butterfly probe, fail %d
  ", p->name, status);
  }
  
  static void butterfly_detach(struct parport *p)
  {
  	struct butterfly	*pp;

  
  	/* 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;

  	/* stop() unregisters child devices too */

  	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);

  	spi_master_put(pp->bitbang.master);

  }
  
  static struct parport_driver butterfly_driver = {
  	.name =		"spi_butterfly",

  	.match_port =	butterfly_attach,

  	.detach =	butterfly_detach,

  	.devmodel = true,

  };

  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_DESCRIPTION("Parport Adapter driver for AVR Butterfly");

  MODULE_LICENSE("GPL");