/*
* 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,
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
* 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));
// 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");
