1 files changed, 323 insertions, 0 deletions
diff --git a/drivers/spi/spi-butterfly.c b/drivers/spi/spi-butterfly.c
new file mode 100644
index 0000000000..289b445424
--- /dev/null
+++ b/drivers/spi/spi-butterfly.c
@@ -0,0 +1,323 @@
+// 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_controller	*host;
+	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.
+	 */
+
+	host = spi_alloc_host(dev, sizeof(*pp));
+	if (!host) {
+		status = -ENOMEM;
+		goto done;
+	}
+	pp = spi_controller_get_devdata(host);
+
+	/*
+	 * SPI and bitbang hookup
+	 *
+	 * use default setup(), cleanup(), and transfer() methods; and
+	 * only bother implementing mode 0.  Start it later.
+	 */
+	host->bus_num = 42;
+	host->num_chipselect = 2;
+
+	pp->bitbang.master = host;
+	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\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,
+			 dev_name(&pp->dataflash->dev));
+
+	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:
+	spi_controller_put(host);
+done:
+	pr_debug("%s: butterfly probe, fail %d\n", 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_controller_put(pp->bitbang.master);
+}
+
+static struct parport_driver butterfly_driver = {
+	.name =		"spi_butterfly",
+	.match_port =	butterfly_attach,
+	.detach =	butterfly_detach,
+	.devmodel = true,
+};
+module_parport_driver(butterfly_driver);
+
+MODULE_DESCRIPTION("Parport Adapter driver for AVR Butterfly");
+MODULE_LICENSE("GPL");