[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>
diff --git a/drivers/spi/spi_butterfly.c b/drivers/spi/spi_butterfly.c
new file mode 100644
index 0000000..79a3c59
--- /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");