path: root/drivers/gpio/gpio-pcf857x.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
 *
 * Copyright (C) 2007 David Brownell
 */

#include <linux/gpio/driver.h>
#include <linux/i2c.h>
#include <linux/platform_data/pcf857x.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/spinlock.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);

#ifdef CONFIG_OF
static const struct of_device_id pcf857x_of_table[] = {
	{ .compatible = "nxp,pcf8574" },
	{ .compatible = "nxp,pcf8574a" },
	{ .compatible = "nxp,pca8574" },
	{ .compatible = "nxp,pca9670" },
	{ .compatible = "nxp,pca9672" },
	{ .compatible = "nxp,pca9674" },
	{ .compatible = "nxp,pcf8575" },
	{ .compatible = "nxp,pca8575" },
	{ .compatible = "nxp,pca9671" },
	{ .compatible = "nxp,pca9673" },
	{ .compatible = "nxp,pca9675" },
	{ .compatible = "maxim,max7328" },
	{ .compatible = "maxim,max7329" },
	{ }
};
MODULE_DEVICE_TABLE(of, pcf857x_of_table);
#endif

/*
 * 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 irq_chip		irqchip;
	struct i2c_client	*client;
	struct mutex		lock;		/* protect 'out' */
	unsigned		out;		/* software latch */
	unsigned		status;		/* current status */
	unsigned		irq_enabled;	/* enabled irqs */

	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 = gpiochip_get_data(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 = gpiochip_get_data(chip);
	int		value;

	value = gpio->read(gpio->client);
	return (value < 0) ? value : !!(value & (1 << offset));
}

static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
{
	struct pcf857x	*gpio = gpiochip_get_data(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 irqreturn_t pcf857x_irq(int irq, void *data)
{
	struct pcf857x  *gpio = data;
	unsigned long change, i, status;

	status = gpio->read(gpio->client);

	/*
	 * call the interrupt handler iff gpio is used as
	 * interrupt source, just to avoid bad irqs
	 */
	mutex_lock(&gpio->lock);
	change = (gpio->status ^ status) & gpio->irq_enabled;
	gpio->status = status;
	mutex_unlock(&gpio->lock);

	for_each_set_bit(i, &change, gpio->chip.ngpio)
		handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i));

	return IRQ_HANDLED;
}

/*
 * NOP functions
 */
static void noop(struct irq_data *data) { }

static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
{
	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);

	return irq_set_irq_wake(gpio->client->irq, on);
}

static void pcf857x_irq_enable(struct irq_data *data)
{
	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);

	gpio->irq_enabled |= (1 << data->hwirq);
}

static void pcf857x_irq_disable(struct irq_data *data)
{
	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);

	gpio->irq_enabled &= ~(1 << data->hwirq);
}

static void pcf857x_irq_bus_lock(struct irq_data *data)
{
	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);

	mutex_lock(&gpio->lock);
}

static void pcf857x_irq_bus_sync_unlock(struct irq_data *data)
{
	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);

	mutex_unlock(&gpio->lock);
}

/*-------------------------------------------------------------------------*/

static int pcf857x_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct pcf857x_platform_data	*pdata = dev_get_platdata(&client->dev);
	struct device_node		*np = client->dev.of_node;
	struct pcf857x			*gpio;
	unsigned int			n_latch = 0;
	int				status;

	if (IS_ENABLED(CONFIG_OF) && np)
		of_property_read_u32(np, "lines-initial-states", &n_latch);
	else if (pdata)
		n_latch