340 lines
8.6 KiB
C
340 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* Driver for LM70EVAL-LLP board for the LM70 sensor
|
|
*
|
|
* Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
|
|
*/
|
|
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
|
|
#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.rst. 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,
|
|
unsigned flags)
|
|
{
|
|
return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
|
|
}
|
|
|
|
static void spi_lm70llp_attach(struct parport *p)
|
|
{
|
|
struct pardevice *pd;
|
|
struct spi_lm70llp *pp;
|
|
struct spi_master *master;
|
|
int status;
|
|
struct pardev_cb lm70llp_cb;
|
|
|
|
if (lm70llp) {
|
|
pr_warn("spi_lm70llp instance already loaded. Aborting.\n");
|
|
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);
|
|
|
|
/*
|
|
* SPI and bitbang hookup.
|
|
*/
|
|
pp->bitbang.master = 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;
|
|
memset(&lm70llp_cb, 0, sizeof(lm70llp_cb));
|
|
lm70llp_cb.private = pp;
|
|
lm70llp_cb.flags = PARPORT_FLAG_EXCL;
|
|
pd = parport_register_dev_model(p, DRVNAME, &lm70llp_cb, 0);
|
|
|
|
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) {
|
|
dev_warn(&pd->dev, "spi_bitbang_start failed with status %d\n",
|
|
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 {
|
|
dev_warn(&pd->dev, "spi_new_device failed\n");
|
|
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:
|
|
spi_master_put(master);
|
|
out_fail:
|
|
pr_info("spi_lm70llp probe fail, status %d\n", 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);
|
|
|
|
spi_master_put(pp->bitbang.master);
|
|
|
|
lm70llp = NULL;
|
|
}
|
|
|
|
static struct parport_driver spi_lm70llp_drv = {
|
|
.name = DRVNAME,
|
|
.match_port = spi_lm70llp_attach,
|
|
.detach = spi_lm70llp_detach,
|
|
.devmodel = true,
|
|
};
|
|
|
|
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");
|