+/*
+ * 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.
+ *
+ * idea:
+ * separate the butterfly driver into a hotpluggable SPI master controller
+ * use a board description file, which loads the:
+ * - the SPI master controller
+ * - the SPI protocoll driver
+ * call spi_new_device with
+ - spi_master = butterfly parport driver (or parameter configurable)
+ - spi_board_info = infos about Mauro-Lite
+
+ */
+#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>
+
+
+
+/*
+ * 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.
+ */
+
+/*
+ * spi_device
+ * todo:
+ * - implement SPI mode 1,2,3 is yet missing
+ * - prevent ugly handling of global butterfly structure
+ * - use serial subsystem
+ * - make stuff module configurable during runtime
+ */
+
+/* DATA output bits (pins 2..9 == D0..D7) */
+#define MODALIASLEN 10
+#define DRVNAME "spi_butterfly"
+#define DRIVER_VERSION "0.2"
+
+#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 */
+
+/*
+ * Parallel
+ * Port Direction Signal
+ * ----------- --------- ------------
+ * D0 2 --> SCLK
+ * D1 3 --> nRESET
+ * D2 4 --> --
+ * D3 5 --> --
+ * D4 6 --> --
+ * D5 7 --> --
+ * D6 8 --> --
+ * D7 9 --> MOSI
+ * GND 25 - GND
+ * Busy 11 <-- MISO
+ * Paper 12 <-- --
+ * Select 13 <-- --
+ * Feed 14 --> --
+ * Error 15 <-- --
+ * Init 16 --> --
+ * Select 17 --> nCS
+ */
+
+//*****************************************************************************
+// Globals
+//*****************************************************************************
+/* module parameters */
+static char modalias[MODALIASLEN] = "maurol";
+
+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; /* hold copy of partport to be faster */
+
+ struct spi_message *msg;
+ struct spi_device *butterfly;
+ struct spi_board_info info;
+
+};
+
+/*----------------------------------------------------------------------*/
+
+
+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; /* use parport mirror to be faster */
+}
+
+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; /* use parport mirror to be faster */
+}
+
+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);
+
+#if 0
+ /* 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);
+#else
+ u8 bit, byte = pp->lastbyte;
+
+ bit = butterfly_nreset;
+
+ if (value)
+ byte &= ~bit;
+ else
+ byte |= bit;
+ parport_write_data(pp->port, byte);
+ pp->lastbyte = byte; /* use parport mirror to be faster */
+#endif
+}
+
+
+/* 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);
+}
+
+/*----------------------------------------------------------------------*/
+
+/* 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);
+
+ master->bus_num = -1; /* dynamic alloc of a bus number */
+ master->num_chipselect = 1;
+
+ /*
+ * SPI and bitbang hookup
+ *
+ * use default setup(), cleanup(), and transfer() methods; and
+ * only bother implementing mode 0. Start it later.
+ */
+ pp->bitbang.master = spi_master_get(master);
+ pp->bitbang.chipselect = butterfly_chipselect;
+ pp->bitbang.txrx_word[SPI_MODE_0] = butterfly_txrx_word_mode0;
+ pp->bitbang.flags = SPI_3WIRE; // ####################################
+
+ /*
+ * parport hookup
+ */
+ pp->port = p;
+ pd = parport_register_device(p, DRVNAME,
+ NULL, NULL, NULL,
+ 0 /* FLAGS */, pp); //PARPORT_FLAG_EXCL, pp);
+ if (!pd) {
+ status = -ENOMEM;
+ goto clean0;
+ }
+ pp->pd = pd;
+
+ status = parport_claim(pd);
+ if (status < 0)
+ goto clean1;
+
+ pp->lastbyte = 0;
+ parport_write_data(pp->port, pp->lastbyte);
+
+ /*
+ * Butterfly reset, powerup, run firmware
+ */
+ pr_debug("%s: powerup/reset Butterfly\n", DRVNAME);
+
+ /* 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);
+
+#if 0
+ /* take it out of reset; assume long reset delay */
+ pp->lastbyte |= butterfly_nreset;
+ parport_write_data(pp->port, pp->lastbyte);
+ msleep(10);
+
+ /* take reset as trigger signal ############# */
+ pp->lastbyte &= ~butterfly_nreset;
+ parport_write_data(pp->port, pp->lastbyte);
+#endif
+
+ /*
+ * Start SPI ... for now, hide that we're two physical busses.
+ */
+ status = spi_bitbang_start(&pp->bitbang);
+ if (status < 0) {
+ pr_warning("%s: spi_bitbang_start failed with status %d\n",
+ DRVNAME, status);
+ goto clean2;
+ }
+
+ /*
+ * The modalias name MUST match the device_driver name
+ * for the bus glue code to match and subsequently bind them.
+ * We are binding to the generic drivers/hwmon/lm70.c device
+ * driver.
+ */
+ if (modalias[0]) {
+ pr_info("%s: Will load protocol driver: '%s'!\n", DRVNAME, modalias);
+ } else goto clean2;
+
+ /* need to make this parameter loadable */
+ strcpy(pp->info.modalias, modalias);
+ pp->info.max_speed_hz = 15 * 1000 * 1000;
+ pp->info.chip_select = 0; // 0: .. 1:
+ pp->info.mode = SPI_3WIRE | SPI_MODE_0; // ################
+
+ /* Enable access to our primary data structure via
+ * the board info's (void *)controller_data.
+ */
+ pp->info.platform_data = NULL; // here we should add data structures for subsystem driver ???
+ pp->info.controller_data = pp; /* save my structure for later use */
+ pp->butterfly = spi_new_device(pp->bitbang.master, &pp->info);
+ if (pp->butterfly)
+ pr_info("%s: SPI tty at %s\n", DRVNAME,
+ pp->butterfly->dev.bus_id);
+ else {
+ pr_warning("%s: spi_new_device failed\n", DRVNAME);
+ status = -ENODEV;
+ goto out_bitbang_stop;
+ }
+ // pp->butterfly->bits_per_word=16; // ###############
+
+ /* get spi_bitbang_transfer either via global Symbol, or better
+ * ask it from the driver structure
+ */
+ pp->msg = spi_message_alloc(1, GFP_KERNEL);
+ if (master) { /* the same address is also saved in pp->bitbang.master or pp->butterfly->master */
+ struct spi_message *spi_msg;
+ spi_msg = pp->msg;
+ if (spi_msg) {
+ // spi_message_init(spi_msg);
+ pr_info("Alloc SPI message buffer\n");
+ spi_msg->spi = pp->butterfly;
+ spi_msg->actual_length = 1;
+#if 0
+ spi_msg->list_head ... Addresse der ersten SPI transfer struct
+
+
+ spi_msg->tx_buf = ;
+ spi_msg->len = 1;
+ spi_msg->cs_change = 1;
+ spi_msg->delay_usecs = 0;
+
+ /* fill up message */
+ master->transfer(pp->butterfly, spi_msg);
+#endif
+ }
+ }
+ butterfly = pp;
+ return;
+
+out_bitbang_stop:
+ spi_bitbang_stop(&pp->bitbang);
+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", DRVNAME, 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;
+ if (pp->msg) {
+ spi_message_free(pp->msg);
+ pr_info("Dealloc SPI message buffer\n");
+ }
+
+ /* 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);
+
+ butterfly = NULL;
+}
+
+static struct parport_driver butterfly_driver = {
+ .name = DRVNAME,
+ .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 SPI tty Butterfly");
+MODULE_LICENSE("GPL");
+
+module_param_string(spi_pdrv, modalias, sizeof(modalias), S_IRUGO);
+MODULE_PARM_DESC(spi_pdrv, "spi protocol driver name");
+
+MODULE_INFO(Version, DRIVER_VERSION);
projects / pub / spi-gpio-pp.git / commitdiff