371 строка
9.8 KiB
C
371 строка
9.8 KiB
C
/*
|
|
* pcf857x - 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/kernel.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/gpio.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/i2c/pcf857x.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 },
|
|
{ }
|
|
};
|
|
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' */
|
|
unsigned out; /* software latch */
|
|
};
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
/* Talk to 8-bit I/O expander */
|
|
|
|
static int pcf857x_input8(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 = i2c_smbus_write_byte(gpio->client, gpio->out);
|
|
mutex_unlock(&gpio->lock);
|
|
|
|
return status;
|
|
}
|
|
|
|
static int pcf857x_get8(struct gpio_chip *chip, unsigned offset)
|
|
{
|
|
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
|
|
s32 value;
|
|
|
|
value = i2c_smbus_read_byte(gpio->client);
|
|
return (value < 0) ? 0 : (value & (1 << offset));
|
|
}
|
|
|
|
static int pcf857x_output8(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 = i2c_smbus_write_byte(gpio->client, gpio->out);
|
|
mutex_unlock(&gpio->lock);
|
|
|
|
return status;
|
|
}
|
|
|
|
static void pcf857x_set8(struct gpio_chip *chip, unsigned offset, int value)
|
|
{
|
|
pcf857x_output8(chip, offset, value);
|
|
}
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
/* Talk to 16-bit I/O expander */
|
|
|
|
static int i2c_write_le16(struct i2c_client *client, u16 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_input16(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 = i2c_write_le16(gpio->client, gpio->out);
|
|
mutex_unlock(&gpio->lock);
|
|
|
|
return status;
|
|
}
|
|
|
|
static int pcf857x_get16(struct gpio_chip *chip, unsigned offset)
|
|
{
|
|
struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
|
|
int value;
|
|
|
|
value = i2c_read_le16(gpio->client);
|
|
return (value < 0) ? 0 : (value & (1 << offset));
|
|
}
|
|
|
|
static int pcf857x_output16(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 = i2c_write_le16(gpio->client, gpio->out);
|
|
mutex_unlock(&gpio->lock);
|
|
|
|
return status;
|
|
}
|
|
|
|
static void pcf857x_set16(struct gpio_chip *chip, unsigned offset, int value)
|
|
{
|
|
pcf857x_output16(chip, offset, value);
|
|
}
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
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 = client->dev.platform_data;
|
|
if (!pdata) {
|
|
dev_dbg(&client->dev, "no platform data\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Allocate, initialize, and register this gpio_chip. */
|
|
gpio = kzalloc(sizeof *gpio, GFP_KERNEL);
|
|
if (!gpio)
|
|
return -ENOMEM;
|
|
|
|
mutex_init(&gpio->lock);
|
|
|
|
gpio->chip.base = pdata->gpio_base;
|
|
gpio->chip.can_sleep = 1;
|
|
gpio->chip.dev = &client->dev;
|
|
gpio->chip.owner = THIS_MODULE;
|
|
|
|
/* 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.
|
|
*/
|
|
gpio->chip.ngpio = id->driver_data;
|
|
if (gpio->chip.ngpio == 8) {
|
|
gpio->chip.direction_input = pcf857x_input8;
|
|
gpio->chip.get = pcf857x_get8;
|
|
gpio->chip.direction_output = pcf857x_output8;
|
|
gpio->chip.set = pcf857x_set8;
|
|
|
|
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->chip.direction_input = pcf857x_input16;
|
|
gpio->chip.get = pcf857x_get16;
|
|
gpio->chip.direction_output = pcf857x_output16;
|
|
gpio->chip.set = pcf857x_set16;
|
|
|
|
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->n_latch;
|
|
|
|
status = gpiochip_add(&gpio->chip);
|
|
if (status < 0)
|
|
goto fail;
|
|
|
|
/* NOTE: these chips can issue "some pin-changed" IRQs, which we
|
|
* don't yet even try to use. Among other issues, the relevant
|
|
* genirq state isn't available to modular drivers; and most irq
|
|
* methods can't be called from sleeping contexts.
|
|
*/
|
|
|
|
dev_info(&client->dev, "gpios %d..%d on a %s%s\n",
|
|
gpio->chip.base,
|
|
gpio->chip.base + gpio->chip.ngpio - 1,
|
|
client->name,
|
|
client->irq ? " (irq ignored)" : "");
|
|
|
|
/* Let platform code set up the GPIOs and their users.
|
|
* Now is the first time anyone could use them.
|
|
*/
|
|
if (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);
|
|
}
|
|
|
|
return 0;
|
|
|
|
fail:
|
|
dev_dbg(&client->dev, "probe error %d for '%s'\n",
|
|
status, client->name);
|
|
kfree(gpio);
|
|
return status;
|
|
}
|
|
|
|
static int pcf857x_remove(struct i2c_client *client)
|
|
{
|
|
struct pcf857x_platform_data *pdata = client->dev.platform_data;
|
|
struct pcf857x *gpio = i2c_get_clientdata(client);
|
|
int status = 0;
|
|
|
|
if (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;
|
|
}
|
|
}
|
|
|
|
status = gpiochip_remove(&gpio->chip);
|
|
if (status == 0)
|
|
kfree(gpio);
|
|
else
|
|
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");
|