linux/drivers/spi/spi_lm70llp.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

352 lines
9.2 KiB
C

/*
* spi_lm70llp.c - driver for LM70EVAL-LLP board for the LM70 sensor
*
* Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
*
* 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/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/parport.h>
#include <linux/sysfs.h>
#include <linux/workqueue.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
/*
* The LM70 communicates with a host processor using a 3-wire variant of
* the SPI/Microwire bus interface. This driver specifically supports an
* NS LM70 LLP Evaluation Board, interfacing to a PC using its parallel
* port to bitbang an SPI-parport bridge. Accordingly, this is an SPI
* master controller driver. The hwmon/lm70 driver is a "SPI protocol
* driver", layered on top of this one and usable without the lm70llp.
*
* Datasheet and Schematic:
* The LM70 is a temperature sensor chip from National Semiconductor; its
* datasheet is available at http://www.national.com/pf/LM/LM70.html
* The schematic for this particular board (the LM70EVAL-LLP) is
* available (on page 4) here:
* http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf
*
* Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is
* (heavily) based on spi-butterfly by David Brownell.
*
* The LM70 LLP connects to the PC parallel port in the following manner:
*
* Parallel LM70 LLP
* Port Direction JP2 Header
* ----------- --------- ------------
* D0 2 - -
* D1 3 --> V+ 5
* D2 4 --> V+ 5
* D3 5 --> V+ 5
* D4 6 --> V+ 5
* D5 7 --> nCS 8
* D6 8 --> SCLK 3
* D7 9 --> SI/O 5
* GND 25 - GND 7
* Select 13 <-- SI/O 1
*
* Note that parport pin 13 actually gets inverted by the transistor
* arrangement which lets either the parport or the LM70 drive the
* SI/SO signal (see the schematic for details).
*/
#define DRVNAME "spi-lm70llp"
#define lm70_INIT 0xBE
#define SIO 0x10
#define nCS 0x20
#define SCLK 0x40
/*-------------------------------------------------------------------------*/
struct spi_lm70llp {
struct spi_bitbang bitbang;
struct parport *port;
struct pardevice *pd;
struct spi_device *spidev_lm70;
struct spi_board_info info;
//struct device *dev;
};
/* REVISIT : ugly global ; provides "exclusive open" facility */
static struct spi_lm70llp *lm70llp;
/*-------------------------------------------------------------------*/
static inline struct spi_lm70llp *spidev_to_pp(struct spi_device *spi)
{
return spi->controller_data;
}
/*---------------------- LM70 LLP eval board-specific inlines follow */
/* NOTE: we don't actually need to reread the output values, since they'll
* still be what we wrote before. Plus, going through parport builds in
* a ~1ms/operation delay; these SPI transfers could easily be faster.
*/
static inline void deassertCS(struct spi_lm70llp *pp)
{
u8 data = parport_read_data(pp->port);
data &= ~0x80; /* pull D7/SI-out low while de-asserted */
parport_write_data(pp->port, data | nCS);
}
static inline void assertCS(struct spi_lm70llp *pp)
{
u8 data = parport_read_data(pp->port);
data |= 0x80; /* pull D7/SI-out high so lm70 drives SO-in */
parport_write_data(pp->port, data & ~nCS);
}
static inline void clkHigh(struct spi_lm70llp *pp)
{
u8 data = parport_read_data(pp->port);
parport_write_data(pp->port, data | SCLK);
}
static inline void clkLow(struct spi_lm70llp *pp)
{
u8 data = parport_read_data(pp->port);
parport_write_data(pp->port, data & ~SCLK);
}
/*------------------------- SPI-LM70-specific inlines ----------------------*/
static inline void spidelay(unsigned d)
{
udelay(d);
}
static inline void setsck(struct spi_device *s, int is_on)
{
struct spi_lm70llp *pp = spidev_to_pp(s);
if (is_on)
clkHigh(pp);
else
clkLow(pp);
}
static inline void setmosi(struct spi_device *s, int is_on)
{
/* FIXME update D7 ... this way we can put the chip
* into shutdown mode and read the manufacturer ID,
* but we can't put it back into operational mode.
*/
}
/*
* getmiso:
* Why do we return 0 when the SIO line is high and vice-versa?
* The fact is, the lm70 eval board from NS (which this driver drives),
* is wired in just such a way : when the lm70's SIO goes high, a transistor
* switches it to low reflecting this on the parport (pin 13), and vice-versa.
*/
static inline int getmiso(struct spi_device *s)
{
struct spi_lm70llp *pp = spidev_to_pp(s);
return ((SIO == (parport_read_status(pp->port) & SIO)) ? 0 : 1 );
}
/*--------------------------------------------------------------------*/
#include "spi_bitbang_txrx.h"
static void lm70_chipselect(struct spi_device *spi, int value)
{
struct spi_lm70llp *pp = spidev_to_pp(spi);
if (value)
assertCS(pp);
else
deassertCS(pp);
}
/*
* Our actual bitbanger routine.
*/
static u32 lm70_txrx(struct spi_device *spi, unsigned nsecs, u32 word, u8 bits)
{
return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits);
}
static void spi_lm70llp_attach(struct parport *p)
{
struct pardevice *pd;
struct spi_lm70llp *pp;
struct spi_master *master;
int status;
if (lm70llp) {
printk(KERN_WARNING
"%s: spi_lm70llp instance already loaded. Aborting.\n",
DRVNAME);
return;
}
/* TODO: this just _assumes_ a lm70 is there ... no probe;
* the lm70 driver could verify it, reading the manf ID.
*/
master = spi_alloc_master(p->physport->dev, sizeof *pp);
if (!master) {
status = -ENOMEM;
goto out_fail;
}
pp = spi_master_get_devdata(master);
master->bus_num = -1; /* dynamic alloc of a bus number */
master->num_chipselect = 1;
/*
* SPI and bitbang hookup.
*/
pp->bitbang.master = spi_master_get(master);
pp->bitbang.chipselect = lm70_chipselect;
pp->bitbang.txrx_word[SPI_MODE_0] = lm70_txrx;
pp->bitbang.flags = SPI_3WIRE;
/*
* Parport hookup
*/
pp->port = p;
pd = parport_register_device(p, DRVNAME,
NULL, NULL, NULL,
PARPORT_FLAG_EXCL, pp);
if (!pd) {
status = -ENOMEM;
goto out_free_master;
}
pp->pd = pd;
status = parport_claim(pd);
if (status < 0)
goto out_parport_unreg;
/*
* Start SPI ...
*/
status = spi_bitbang_start(&pp->bitbang);
if (status < 0) {
printk(KERN_WARNING
"%s: spi_bitbang_start failed with status %d\n",
DRVNAME, status);
goto out_off_and_release;
}
/*
* 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.
*/
strcpy(pp->info.modalias, "lm70");
pp->info.max_speed_hz = 6 * 1000 * 1000;
pp->info.chip_select = 0;
pp->info.mode = SPI_3WIRE | SPI_MODE_0;
/* power up the chip, and let the LM70 control SI/SO */
parport_write_data(pp->port, lm70_INIT);
/* Enable access to our primary data structure via
* the board info's (void *)controller_data.
*/
pp->info.controller_data = pp;
pp->spidev_lm70 = spi_new_device(pp->bitbang.master, &pp->info);
if (pp->spidev_lm70)
dev_dbg(&pp->spidev_lm70->dev, "spidev_lm70 at %s\n",
dev_name(&pp->spidev_lm70->dev));
else {
printk(KERN_WARNING "%s: spi_new_device failed\n", DRVNAME);
status = -ENODEV;
goto out_bitbang_stop;
}
pp->spidev_lm70->bits_per_word = 8;
lm70llp = pp;
return;
out_bitbang_stop:
spi_bitbang_stop(&pp->bitbang);
out_off_and_release:
/* power down */
parport_write_data(pp->port, 0);
mdelay(10);
parport_release(pp->pd);
out_parport_unreg:
parport_unregister_device(pd);
out_free_master:
(void) spi_master_put(master);
out_fail:
pr_info("%s: spi_lm70llp probe fail, status %d\n", DRVNAME, status);
}
static void spi_lm70llp_detach(struct parport *p)
{
struct spi_lm70llp *pp;
if (!lm70llp || lm70llp->port != p)
return;
pp = lm70llp;
spi_bitbang_stop(&pp->bitbang);
/* power down */
parport_write_data(pp->port, 0);
parport_release(pp->pd);
parport_unregister_device(pp->pd);
(void) spi_master_put(pp->bitbang.master);
lm70llp = NULL;
}
static struct parport_driver spi_lm70llp_drv = {
.name = DRVNAME,
.attach = spi_lm70llp_attach,
.detach = spi_lm70llp_detach,
};
static int __init init_spi_lm70llp(void)
{
return parport_register_driver(&spi_lm70llp_drv);
}
module_init(init_spi_lm70llp);
static void __exit cleanup_spi_lm70llp(void)
{
parport_unregister_driver(&spi_lm70llp_drv);
}
module_exit(cleanup_spi_lm70llp);
MODULE_AUTHOR("Kaiwan N Billimoria <kaiwan@designergraphix.com>");
MODULE_DESCRIPTION(
"Parport adapter for the National Semiconductor LM70 LLP eval board");
MODULE_LICENSE("GPL");