/*
* Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
*
* Copyright (C) 2007 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/gpio.h>
#include <linux/i2c.h>
#include <linux/i2c/pcf857x.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
static const struct i2c_device_id pcf857x_id[] = {
{ "pcf8574", 8 },
{ "pcf8574a", 8 },
{ "pca8574", 8 },
{ "pca9670", 8 },
{ "pca9672", 8 },
{ "pca9674", 8 },
{ "pcf8575", 16 },
{ "pca8575", 16 },
{ "pca9671", 16 },
{ "pca9673", 16 },
{ "pca9675", 16 },
{ "max7328", 8 },
{ "max7329", 8 },
{ "tca9554", 8 },
{ }
};
MODULE_DEVICE_TABLE(i2c, pcf857x_id);
/*
* The pcf857x, pca857x, and pca967x chips only expose one read and one
* write register. Writing a "one" bit (to match the reset state) lets
* that pin be used as an input; it's not an open-drain model, but acts
* a bit like one. This is described as "quasi-bidirectional"; read the
* chip documentation for details.
*
* Many other I2C GPIO expander chips (like the pca953x models) have
* more complex register models and more conventional circuitry using
* push/pull drivers. They often use the same 0x20..0x27 addresses as
* pcf857x parts, making the "legacy" I2C driver model problematic.
*/
struct pcf857x {
struct gpio_chip chip;
struct i2c_client *client;
struct mutex lock; /* protect 'out' */
struct work_struct work; /* irq demux work */
struct irq_domain *irq_domain; /* for irq demux */
spinlock_t slock; /* protect irq demux */
unsigned out; /* software latch */
unsigned status; /* current status */
int irq; /* real irq number */
int (*write)(struct i2c_client *client, unsigned data);
int (*read)(struct i2c_client *client);
};
/*-------------------------------------------------------------------------*/
/* Talk to 8-bit I/O expander */
static int i2c_write_le8(struct i2c_client *client, unsigned data)
{
return i2c_smbus_write_byte(client, data);
}
static int i2c_read_le8(struct i2c_client *client)
{
return (int)i2c_smbus_read_byte(client);
}
/* Talk to 16-bit I/O expander */
static int i2c_write_le16(struct i2c_client *client, unsigned word)
{
u8 buf[2] = { word & 0xff, word >> 8, };
int status;
status = i2c_master_send(client, buf, 2);
return (status < 0) ? status : 0;
}
static int i2c_read_le16(struct i2c_client *client)
{
u8 buf[2];
int status;
status = i2c_master_recv(client, buf, 2);
if (status < 0)
return status;
return (buf[1] << 8) | buf[0];
}
/*-------------------------------------------------------------------------*/
static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
int status;
mutex_lock(&gpio->lock);
gpio->out |= (1 << offset);
status = gpio->write(gpio->client, gpio->out);
mutex_unlock(&gpio->lock);
return status;
}
static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
int value;
value = gpio->read(gpio->client);
return (value < 0) ? 0 : (value & (1 << offset));
}
static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
unsigned bit = 1 << offset;
int status;
mutex_lock(&gpio->lock);
if (value)
gpio->out |= bit;
else
gpio->out &= ~bit;
status = gpio->write(gpio->client, gpio->out);
mutex_unlock(&gpio->lock);
return status;
}
static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
{
pcf857x_output(chip, offset, value);
}
/*-------------------------------------------------------------------------*/
static int pcf857x_to_irq(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
return irq_create_mapping(gpio->irq_domain, offset);
}
static void pcf857x_irq_demux_work(struct work_struct *work)
{
struct pcf857x *gpio = container_of(work,
struct pcf857x,
work);
unsigned long change, i, status, flags;
status = gpio->read(gpio->client);
spin_lock_irqsave(&gpio->slock, flags);
change = gpio->status ^ status;
for_each_set_bit(i, &change, gpio->chip.ngpio)
generic_handle_irq(irq_find_mapping(gpio->irq_domain, i));
gpio->status = status;
spin_unlock_irqrestore(&gpio->slock, flags);
}
static irqreturn_t pcf857x_irq_demux(int irq, void *data)
{
struct pcf857x *gpio = data;
/*
* pcf857x can't read/write data here,
* since i2c data access might go to sleep.
*/
schedule_work(&gpio->work);
return IRQ_HANDLED;
}
static int pcf857x_irq_domain_map(struct irq_domain *domain, unsigned int virq,
irq_hw_number_t hw)
{
irq_set_chip_and_handler(virq,
&dummy_irq_chip,
handle_level_irq);
return 0;
}
static struct irq_domain_ops pcf857x_irq_domain_ops = {
.map = pcf857x_irq_domain_map,
};
static void pcf857x_irq_domain_cleanup(struct pcf857x *gpio)
{
if (gpio->irq_domain)
irq_domain_remove(gpio->irq_domain);
if (gpio->irq)
free_irq(gpio->irq, gpio);
}
static int pcf857x_irq_domain_init(struct pcf857x *gpio,
struct i2c_client *client)
{
int status;
gpio->irq_domain = irq_domain_add_linear(client->dev.of_node,
gpio->chip.ngpio,
&pcf857x_irq_domain_ops,
NULL);
if (!gpio->irq_domain)
goto fail;
/* enable real irq */
status = request_irq(client->irq, pcf857x_irq_demux, 0,
dev_name(&client->dev), gpio);
if (status)
goto fail;
/* enable gpio_to_irq() */
INIT_WORK(&gpio->work, pcf857x_irq_demux_work);
gpio->chip.to_irq = pcf857x_to_irq;
gpio->irq = client->irq;
return 0;
fail:
pcf857x_irq_domain_cleanup(gpio);
return -EINVAL;
}
/*-------------------------------------------------------------------------*/
static int pcf857x_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct pcf857x_platform_data *pdata;
struct pcf857x *gpio;
int status;
pdata = dev_get_platdata(&client->dev);
if (!pdata) {
dev_dbg(&client->dev, "no platform data\n");
}
/* Allocate, initialize, and register this gpio_chip. */
gpio = devm_kzalloc(&client->dev, sizeof(*gpio), GFP_KERNEL);
if (!gpio)
return -ENOMEM;
mutex_init(&gpio->lock);
spin_lock_init(&gpio->slock);
gpio->chip.base = pdata ? pdata->gpio_base : -1;
gpio->chip.can_sleep = 1;
gpio->chip.dev = &client->dev;
gpio->chip.owner = THIS_MODULE;
gpio->chip.get = pcf857x_get;
gpio->chip.set = pcf857x_set;
gpio->chip.direction_input = pcf857x_input;
gpio->chip.direction_output = pcf857x_output;
gpio->chip.ngpio = id->driver_data;
/* enable gpio_to_irq() if platform has settings */
if (client->irq) {
status = pcf857x_irq_domain_init(gpio, client);
if (status < 0) {
dev_err(&client->dev, "irq_domain init failed\n");
goto fail;
}
}
/* NOTE: the OnSemi jlc1562b is also largely compatible with
* these parts, notably for output. It has a low-resolution
* DAC instead of pin change IRQs; and its inputs can be the
* result of comparators.
*/
/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
* 9670, 9672, 9764, and 9764a use quite a variety.
*
* NOTE: we don't distinguish here between *4 and *4a parts.
*/
if (gpio->chip.ngpio == 8) {
gpio->write = i2c_write_le8;
gpio->read = i2c_read_le8;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_BYTE))
status = -EIO;
/* fail if there's no chip present */
else
status = i2c_smbus_read_byte(client);
/* '75/'75c addresses are 0x20..0x27, just like the '74;
* the '75c doesn't have a current source pulling high.
* 9671, 9673, and 9765 use quite a variety of addresses.
*
* NOTE: we don't distinguish here between '75 and '75c parts.
*/
} else if (gpio->chip.ngpio == 16) {
gpio->write = i2c_write_le16;
gpio->read = i2c_read_le16;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
status = -EIO;
/* fail if there's no chip present */
else
status = i2c_read_le16(client);
} else {
dev_dbg(&client->dev, "unsupported number of gpios\n");
status = -EINVAL;
}
if (status < 0)
goto fail;
gpio->chip.label = client->name;
gpio->client = client;
i2c_set_clientdata(client, gpio);
/* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
* We can't actually know whether a pin is configured (a) as output
* and driving the signal low, or (b) as input and reporting a low
* value ... without knowing the last value written since the chip
* came out of reset (if any). We can't read the latched output.
*
* In short, the only reliable solution for setting up pin direction
* is to do it explicitly. The setup() method can do that, but it
* may cause transient glitching since it can't know the last value
* written (some pins may need to be driven low).
*
* Using pdata->n_latch avoids that trouble. When left initialized
* to zero, our software copy of the "latch" then matches the chip's
* all-ones reset state. Otherwise it flags pins to be driven low.
*/
gpio->out = pdata ? ~pdata->n_latch : ~0;
gpio->status = gpio->out;
status = gpiochip_add(&gpio->chip);
if (status < 0)
goto fail;
/* Let platform code set up the GPIOs and their users.
* Now is the first time anyone could use them.
*/
if (pdata && pdata->setup) {
status = pdata->setup(client,
gpio->chip.base, gpio->chip.ngpio,
pdata->context);
if (status < 0)
dev_warn(&client->dev, "setup --> %d\n", status);
}
dev_info(&client->dev, "probed\n");
return 0;
fail:
dev_dbg(&client->dev, "probe error %d for '%s'\n",
status, client->name);
if (client->irq)
pcf857x_irq_domain_cleanup(gpio);
return status;
}
static int pcf857x_remove(struct i2c_client *client)
{
struct pcf857x_platform_data *pdata = dev_get_platdata(&client->dev);
struct pcf857x *gpio = i2c_get_clientdata(client);
int status = 0;
if (pdata && pdata->teardown) {
status = pdata->teardown(client,
gpio->chip.base, gpio->chip.ngpio,
pdata->context);
if (status < 0) {
dev_err(&client->dev, "%s --> %d\n",
"teardown", status);
return status;
}
}
if (client->irq)
pcf857x_irq_domain_cleanup(gpio);
status = gpiochip_remove(&gpio->chip);
if (status)
dev_err(&client->dev, "%s --> %d\n", "remove", status);
return status;
}
static struct i2c_driver pcf857x_driver = {
.driver = {
.name = "pcf857x",
.owner = THIS_MODULE,
},
.probe = pcf857x_probe,
.remove = pcf857x_remove,
.id_table = pcf857x_id,
};
static int __init pcf857x_init(void)
{
return i2c_add_driver(&pcf857x_driver);
}
/* register after i2c postcore initcall and before
* subsys initcalls that may rely on these GPIOs
*/
subsys_initcall(pcf857x_init);
static void __exit pcf857x_exit(void)
{
i2c_del_driver(&pcf857x_driver);
}
module_exit(pcf857x_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Brownell");
