1 files changed, 369 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
new file mode 100644
index 00000000000..7369fdda92b
--- /dev/null
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -0,0 +1,369 @@
+/*
+ * 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");
+	}
+
+	/* 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 ? pdata->gpio_base : -1;
+	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 ? ~pdata->n_latch : ~0;
+
+	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 && 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 && 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");