1 files changed, 447 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
new file mode 100644
index 000000000..e98ea47d7
--- /dev/null
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -0,0 +1,447 @@
+// 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 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);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	gpiochip_enable_irq(&gpio->chip, hwirq);
+	gpio->irq_enabled |= (1 << hwirq);
+}
+
+static void pcf857x_irq_disable(struct irq_data *data)
+{
+	struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
+	irq_hw_number_t hwirq = irqd_to_hwirq(data);
+
+	gpio->irq_enabled &= ~(1 << hwirq);
+	gpiochip_disable_irq(&gpio->chip, 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 const struct irq_chip pcf857x_irq_chip = {
+	.name			= "pcf857x",
+	.irq_enable		= pcf857x_irq_enable,
+	.irq_disable		= pcf857x_irq_disable,
+	.irq_ack		= noop,
+	.irq_mask		= noop,
+	.irq_unmask		= noop,
+	.irq_set_wake		= pcf857x_irq_set_wake,
+	.irq_bus_lock		= pcf857x_irq_bus_lock,
+	.irq_bus_sync_unlock	= pcf857x_irq_bus_sync_unlock,
+	.flags			= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
+/*-------------------------------------------------------------------------*/
+
+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 = pdata->n_latch;
+	else
+		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);
+
+	gpio->chip.base			= pdata ? pdata->gpio_base : -1;
+	gpio->chip.can_sleep		= true;
+	gpio->chip.parent		= &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;
+
+	/* 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 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 = ~n_latch;
+	gpio->status = gpio->read(gpio->client);
+
+	/* Enable irqchip if we have an interrupt */
+	if (client->irq) {
+		struct gpio_irq_chip *girq;
+
+		status = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, pcf857x_irq, IRQF_ONESHOT |
+					IRQF_TRIGGER_FALLING | IRQF_SHARED,
+					dev_name(&client->dev), gpio);
+		if (status)
+			goto fail;
+
+		girq = &gpio->chip.irq;
+		gpio_irq_chip_set_chip(girq, &pcf857x_irq_chip);
+		/* This will let us handle the parent IRQ in the driver */
+		girq->parent_handler = NULL;
+		girq->num_parents = 0;
+		girq->parents = NULL;
+		girq->default_type = IRQ_TYPE_NONE;
+		girq->handler = handle_level_irq;
+		girq->threaded = true;
+	}
+
+	status = devm_gpiochip_add_data(&client->dev, &gpio->chip, gpio);
+	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);
+
+	return status;
+}
+
+static void pcf857x_remove(struct i2c_client *client)
+{
+	struct pcf857x_platform_data	*pdata = dev_get_platdata(&client->dev);
+	struct pcf857x			*gpio = i2c_get_clientdata(client);
+
+	if (pdata && pdata->teardown)
+		pdata->teardown(client, gpio->chip.base, gpio->chip.ngpio,
+				pdata->context);
+}
+
+static void pcf857x_shutdown(struct i2c_client *client)
+{
+	struct pcf857x *gpio = i2c_get_clientdata(client);
+
+	/* Drive all the I/O lines high */
+	gpio->write(gpio->client, BIT(gpio->chip.ngpio) - 1);
+}
+
+static struct i2c_driver pcf857x_driver = {
+	.driver = {
+		.name	= "pcf857x",
+		.of_match_table = of_match_ptr(pcf857x_of_table),
+	},
+	.probe	= pcf857x_probe,
+	.remove	= pcf857x_remove,
+	.shutdown = pcf857x_shutdown,
+	.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");