gpio-mc33880.c
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/*
* MC33880 high-side/low-side switch GPIO driver
* Copyright (c) 2009 Intel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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.
*/
/* Supports:
* Freescale MC33880 high-side/low-side switch
*/
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/spi/spi.h>
#include <linux/spi/mc33880.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/module.h>
#define DRIVER_NAME "mc33880"
/*
* Pin configurations, see MAX7301 datasheet page 6
*/
#define PIN_CONFIG_MASK 0x03
#define PIN_CONFIG_IN_PULLUP 0x03
#define PIN_CONFIG_IN_WO_PULLUP 0x02
#define PIN_CONFIG_OUT 0x01
#define PIN_NUMBER 8
/*
* Some registers must be read back to modify.
* To save time we cache them here in memory
*/
struct mc33880 {
struct mutex lock; /* protect from simultaneous accesses */
u8 port_config;
struct gpio_chip chip;
struct spi_device *spi;
};
static int mc33880_write_config(struct mc33880 *mc)
{
return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
}
static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
{
if (value)
mc->port_config |= 1 << offset;
else
mc->port_config &= ~(1 << offset);
return mc33880_write_config(mc);
}
static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
{
struct mc33880 *mc = container_of(chip, struct mc33880, chip);
mutex_lock(&mc->lock);
__mc33880_set(mc, offset, value);
mutex_unlock(&mc->lock);
}
static int mc33880_probe(struct spi_device *spi)
{
struct mc33880 *mc;
struct mc33880_platform_data *pdata;
int ret;
pdata = dev_get_platdata(&spi->dev);
if (!pdata || !pdata->base) {
dev_dbg(&spi->dev, "incorrect or missing platform data\n");
return -EINVAL;
}
/*
* bits_per_word cannot be configured in platform data
*/
spi->bits_per_word = 8;
ret = spi_setup(spi);
if (ret < 0)
return ret;
mc = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL);
if (!mc)
return -ENOMEM;
mutex_init(&mc->lock);
spi_set_drvdata(spi, mc);
mc->spi = spi;
mc->chip.label = DRIVER_NAME,
mc->chip.set = mc33880_set;
mc->chip.base = pdata->base;
mc->chip.ngpio = PIN_NUMBER;
mc->chip.can_sleep = true;
mc->chip.dev = &spi->dev;
mc->chip.owner = THIS_MODULE;
mc->port_config = 0x00;
/* write twice, because during initialisation the first setting
* is just for testing SPI communication, and the second is the
* "real" configuration
*/
ret = mc33880_write_config(mc);
mc->port_config = 0x00;
if (!ret)
ret = mc33880_write_config(mc);
if (ret) {
dev_err(&spi->dev, "Failed writing to " DRIVER_NAME ": %d\n",
ret);
goto exit_destroy;
}
ret = gpiochip_add(&mc->chip);
if (ret)
goto exit_destroy;
return ret;
exit_destroy:
mutex_destroy(&mc->lock);
return ret;
}
static int mc33880_remove(struct spi_device *spi)
{
struct mc33880 *mc;
int ret;
mc = spi_get_drvdata(spi);
if (mc == NULL)
return -ENODEV;
ret = gpiochip_remove(&mc->chip);
if (!ret)
mutex_destroy(&mc->lock);
else
dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
ret);
return ret;
}
static struct spi_driver mc33880_driver = {
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
},
.probe = mc33880_probe,
.remove = mc33880_remove,
};
static int __init mc33880_init(void)
{
return spi_register_driver(&mc33880_driver);
}
/* register after spi postcore initcall and before
* subsys initcalls that may rely on these GPIOs
*/
subsys_initcall(mc33880_init);
static void __exit mc33880_exit(void)
{
spi_unregister_driver(&mc33880_driver);
}
module_exit(mc33880_exit);
MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
MODULE_LICENSE("GPL v2");