/**
* Copyright (C) 2006 Juergen Beisert, Pengutronix
* Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
* Copyright (C) 2009 Wolfram Sang, Pengutronix
*
* 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.
*
* The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
* 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
* details
* Note:
* - DIN must be stable at the rising edge of clock.
* - when writing:
* - always clock in 16 clocks at once
* - at DIN: D15 first, D0 last
* - D0..D7 = databyte, D8..D14 = commandbyte
* - D15 = low -> write command
* - when reading
* - always clock in 16 clocks at once
* - at DIN: D15 first, D0 last
* - D0..D7 = dummy, D8..D14 = register address
* - D15 = high -> read command
* - raise CS and assert it again
* - always clock in 16 clocks at once
* - at DOUT: D15 first, D0 last
* - D0..D7 contains the data from the first cycle
*
* The driver exports a standard gpiochip interface
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/spi/max7301.h>
#include <linux/gpio.h>
#include <linux/slab.h>
/*
* 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 28
static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
{
struct max7301 *ts = container_of(chip, struct max7301, chip);
u8 *config;
u8 offset_bits, pin_config;
int ret;
/* First 4 pins are unused in the controller */
offset += 4;
offset_bits = (offset & 3) << 1;
config = &ts->port_config[offset >> 2];
if (ts->input_pullup_active & BIT(offset))
pin_config = PIN_CONFIG_IN_PULLUP;
else
pin_config = PIN_CONFIG_IN_WO_PULLUP;
mutex_lock(&ts->lock);
*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
| (pin_config << offset_bits);
ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
mutex_unlock(&ts->lock);
return ret;
}
static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
{
if (value) {
ts->out_level |= 1 << offset;
return ts->write(ts->dev, 0x20 + offset, 0x01);
} else {
ts->out_level &= ~(1 << offset);
return ts->write(ts->dev, 0x20 + offset, 0x00);
}
}
static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
int value)
{
struct max7301 *ts = container_of(chip, struct max7301, chip);
u8 *config;
u8 offset_bits;
int ret;
/* First 4 pins are unused in the controller */
offset += 4;
offset_bits = (offset & 3) << 1;
config = &ts->port_config[offset >> 2];
mutex_lock(&ts->lock);
*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
| (PIN_CONFIG_OUT << offset_bits);
ret = __max7301_set(ts, offset, value);
if (!ret)
ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
mutex_unlock(&ts->lock);
return ret;
}
static int max7301_get(struct gpio_chip *chip, unsigned offset)
{
struct max7301 *ts = container_of(chip, struct max7301, chip);
int config, level = -EINVAL;
/* First 4 pins are unused in the controller */
offset += 4;
mutex_lock(&ts->lock);
config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
& PIN_CONFIG_MASK;
switch (config) {
case PIN_CONFIG_OUT:
/* Output: return cached level */
level = !!(ts->out_level & (1 << offset));
break;
case PIN_CONFIG_IN_WO_PULLUP:
case PIN_CONFIG_IN_PULLUP:
/* Input: read out */
level = ts->read(ts->dev, 0x20 + offset) & 0x01;
}
mutex_unlock(&ts->lock);
return level;
}
static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
{
struct max7301 *ts = container_of(chip, struct max7301, chip);
/* First 4 pins are unused in the controller */
offset += 4;
mutex_lock(&ts->lock);
__max7301_set(ts, offset, value);
mutex_unlock(&ts->lock);
}
int __max730x_probe(struct max7301 *ts)
{
struct device *dev = ts->dev;
struct max7301_platform_data *pdata;
int i, ret;
pdata = dev_get_platdata(dev);
mutex_init(&ts->lock);
dev_set_drvdata(dev, ts);
/* Power up the chip and disable IRQ output */
ts->write(dev, 0x04, 0x01);
if (pdata) {
ts->input_pullup_active = pdata->input_pullup_active;
ts->chip.base = pdata->base;
} else {
ts->chip.base = -1;
}
ts->chip.label = dev->driver->name;
ts->chip.direction_input = max7301_direction_input;
ts->chip.get = max7301_get;
ts->chip.direction_output = max7301_direction_output;
ts->chip.set = max7301_set;
ts->chip.ngpio = PIN_NUMBER;
ts->chip.can_sleep = true;
ts->chip.dev = dev;
ts->chip.owner = THIS_MODULE;
/*
* initialize pullups according to platform data and cache the
* register values for later use.
*/
for (i = 1; i < 8; i++) {
int j;
/*
* initialize port_config with "0xAA", which means
* input with internal pullup disabled. This is needed
* to avoid writing zeros (in the inner for loop),
* which is not allowed according to the datasheet.
*/
ts->port_config[i] = 0xAA;
for (j = 0; j < 4; j++) {
int offset = (i - 1) * 4 + j;
ret = max7301_direction_input(&ts->chip, offset);
if (ret)
goto exit_destroy;
}
}
ret = gpiochip_add(&ts->chip);
if (ret)
goto exit_destroy;
return ret;
exit_destroy:
mutex_destroy(&ts->lock);
return ret;
}
EXPORT_SYMBOL_GPL(__max730x_probe);
int __max730x_remove(struct device *dev)
{
struct max7301 *ts = dev_get_drvdata(dev);
int ret;
if (ts == NULL)
return -ENODEV;
/* Power down the chip and disable IRQ output */
ts->write(dev, 0x04, 0x00);
ret = gpiochip_remove(&ts->chip);
if (!ret)
mutex_destroy(&ts->lock);
else
dev_err(dev, "Failed to remove GPIO controller: %d\n", ret);
return ret;
}
EXPORT_SYMBOL_GPL(__max730x_remove);
MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");
