linux/drivers/spi/spi_butterfly.c
Marek Szyprowski 04bb2a031c spi/bitbang: add support for SPI_MASTER_NO_{TX, RX} modes
This patch adds a new flags argument to bitbang_txrx_be_cpha0 and
bitbang_txrx_be_cpha1 transfer functions. This enables support for
SPI_MASTER_NO_{TX,RX} transfer modes. The change should have no impact
on speed of the existing drivers. bitbank_txrx_* functions are usually
inlined into the drivers. When the argument is equal to constant zero,
the optimizer would be able to eliminate the dead code (flags checks)
easily. Tested on ARM and GCC 4.4.x and in all cases the checks were
eliminated in the inlined function.

Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
2010-07-03 22:45:44 -06:00

357 lines
8.5 KiB
C

/*
* 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
#include "spi_bitbang_txrx.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, 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");