[PATCH] SPI: add spi_butterfly driver

This adds a bitbanging parport based adaptor cable for AVR Butterfly, giving
SPI links to its DataFlash chip and (eventually) firmware running in the card.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 423 insertions, 0 deletions

diff --git a/drivers/spi/spi_butterfly.c b/drivers/spi/spi_butterfly.c
new file mode 100644
index 000000000000..79a3c59615ab
--- /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");