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path: root/drivers/gpio/gpio-pcf857x.c
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Diffstat (limited to 'drivers/gpio/gpio-pcf857x.c')
-rw-r--r--drivers/gpio/gpio-pcf857x.c442
1 files changed, 442 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
new file mode 100644
index 000000000..945f0cda8
--- /dev/null
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -0,0 +1,442 @@
+/*
+ * 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/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 },
+ { "tca9554", 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" },
+ { .compatible = "ti,tca9554" },
+ { }
+};
+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' */
+ spinlock_t slock; /* protect irq demux */
+ unsigned out; /* software latch */
+ unsigned status; /* current status */
+
+ 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 irqreturn_t pcf857x_irq(int irq, void *data)
+{
+ struct pcf857x *gpio = data;
+ unsigned long change, i, status, flags;
+
+ status = gpio->read(gpio->client);
+
+ spin_lock_irqsave(&gpio->slock, flags);
+
+ /*
+ * call the interrupt handler iff gpio is used as
+ * interrupt source, just to avoid bad irqs
+ */
+
+ change = (gpio->status ^ status);
+ for_each_set_bit(i, &change, gpio->chip.ngpio)
+ handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
+ gpio->status = status;
+
+ spin_unlock_irqrestore(&gpio->slock, flags);
+
+ return IRQ_HANDLED;
+}
+
+/*
+ * NOP functions
+ */
+static void noop(struct irq_data *data) { }
+
+static unsigned int noop_ret(struct irq_data *data)
+{
+ return 0;
+}
+
+static int pcf857x_irq_set_wake(struct irq_data *data, unsigned int on)
+{
+ struct pcf857x *gpio = irq_data_get_irq_chip_data(data);
+
+ irq_set_irq_wake(gpio->client->irq, on);
+ return 0;
+}
+
+static struct irq_chip pcf857x_irq_chip = {
+ .name = "pcf857x",
+ .irq_startup = noop_ret,
+ .irq_shutdown = noop,
+ .irq_enable = noop,
+ .irq_disable = noop,
+ .irq_ack = noop,
+ .irq_mask = noop,
+ .irq_unmask = noop,
+ .irq_set_wake = pcf857x_irq_set_wake,
+};
+
+/*-------------------------------------------------------------------------*/
+
+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);
+ spin_lock_init(&gpio->slock);
+
+ gpio->chip.base = pdata ? pdata->gpio_base : -1;
+ gpio->chip.can_sleep = true;
+ 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;
+
+ /* 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->out;
+
+ status = gpiochip_add(&gpio->chip);
+ if (status < 0)
+ goto fail;
+
+ /* Enable irqchip if we have an interrupt */
+ if (client->irq) {
+ status = gpiochip_irqchip_add(&gpio->chip, &pcf857x_irq_chip,
+ 0, handle_level_irq,
+ IRQ_TYPE_NONE);
+ if (status) {
+ dev_err(&client->dev, "cannot add irqchip\n");
+ goto fail_irq;
+ }
+
+ 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_irq;
+
+ gpiochip_set_chained_irqchip(&gpio->chip, &pcf857x_irq_chip,
+ client->irq, NULL);
+ }
+
+ /* 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_irq:
+ gpiochip_remove(&gpio->chip);
+
+fail:
+ dev_dbg(&client->dev, "probe error %d for '%s'\n", status,
+ client->name);
+
+ 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;
+ }
+ }
+
+ gpiochip_remove(&gpio->chip);
+ return status;
+}
+
+static struct i2c_driver pcf857x_driver = {
+ .driver = {
+ .name = "pcf857x",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(pcf857x_of_table),
+ },
+ .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");