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/*

 * 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/kernel.h>

#include <linux/init.h>

#include <linux/delay.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 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

#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,

         * 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;

        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 = 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,

        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

         * 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\n", p->name,

                                pp->dataflash->dev.bus_id);

        // 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:

        pr_debug("%s: butterfly probe, fail %d\n", p->name, status);

}

static void butterfly_detach(struct parport *p)

{

        struct butterfly        *pp;

        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;

        /* stop() unregisters child devices too */

        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);

        (void) spi_master_put(pp->bitbang.master);

}

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

MODULE_LICENSE("GPL");