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gpio: pcf857x: Add OF support

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Add DT bindings for the pcf857x-compatible chips and parse the device
tree node in the driver.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Laurent Pinchart 2013-09-21 20:39:49 +02:00 committed by Linus Walleij
parent e5304db8d7
commit 63f57cd45b
2 changed files with 107 additions and 8 deletions
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71
Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt Normal file
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@ -0,0 +1,71 @@
* PCF857x-compatible I/O expanders
The PCF857x-compatible chips have "quasi-bidirectional" I/O lines that can be
driven high by a pull-up current source or driven low to ground. This combines
the direction and output level into a single bit per line, which can't be read
back. We can't actually know at initialization time whether a line is configured
(a) as output and driving the signal low/high, or (b) as input and reporting a
low/high value, without knowing the last value written since the chip came out
of reset (if any). The only reliable solution for setting up line direction is
thus to do it explicitly.
Required Properties:
- compatible: should be one of the following.
- "maxim,max7328": For the Maxim MAX7378
- "maxim,max7329": For the Maxim MAX7329
- "nxp,pca8574": For the NXP PCA8574
- "nxp,pca8575": For the NXP PCA8575
- "nxp,pca9670": For the NXP PCA9670
- "nxp,pca9671": For the NXP PCA9671
- "nxp,pca9672": For the NXP PCA9672
- "nxp,pca9673": For the NXP PCA9673
- "nxp,pca9674": For the NXP PCA9674
- "nxp,pca9675": For the NXP PCA9675
- "nxp,pcf8574": For the NXP PCF8574
- "nxp,pcf8574a": For the NXP PCF8574A
- "nxp,pcf8575": For the NXP PCF8575
- "ti,tca9554": For the TI TCA9554
- reg: I2C slave address.
- gpio-controller: Marks the device node as a gpio controller.
- #gpio-cells: Should be 2. The first cell is the GPIO number and the second
cell specifies GPIO flags, as defined in <dt-bindings/gpio/gpio.h>. Only the
GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW flags are supported.
Optional Properties:
- lines-initial-states: Bitmask that specifies the initial state of each
line. When a bit is set to zero, the corresponding line will be initialized to
the input (pulled-up) state. When the bit is set to one, the line will be
initialized the the low-level output state. If the property is not specified
all lines will be initialized to the input state.
The I/O expander can detect input state changes, and thus optionally act as
an interrupt controller. When the expander interrupt line is connected all the
following properties must be set. For more information please see the
interrupt controller device tree bindings documentation available at
Documentation/devicetree/bindings/interrupt-controller/interrupts.txt.
- interrupt-controller: Identifies the node as an interrupt controller.
- #interrupt-cells: Number of cells to encode an interrupt source, shall be 2.
- interrupt-parent: phandle of the parent interrupt controller.
- interrupts: Interrupt specifier for the controllers interrupt.
Please refer to gpio.txt in this directory for details of the common GPIO
bindings used by client devices.
Example: PCF8575 I/O expander node
pcf8575: gpio@20 {
compatible = "nxp,pcf8575";
reg = <0x20>;
interrupt-parent = <&irqpin2>;
interrupts = <3 0>;
gpio-controller;
#gpio-cells = <2>;
interrupt-controller;
#interrupt-cells = <2>;
};

44
drivers/gpio/gpio-pcf857x.c
View File

@ -26,6 +26,8 @@
#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>
@ -49,6 +51,27 @@ static const struct i2c_device_id pcf857x_id[] = {
};
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
@ -260,14 +283,18 @@ fail:
static int pcf857x_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct pcf857x_platform_data *pdata;
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;
pdata = dev_get_platdata(&client->dev);
if (!pdata) {
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);
@ -360,11 +387,11 @@ static int pcf857x_probe(struct i2c_client *client,
* 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.
* 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 = pdata ? ~pdata->n_latch : ~0;
gpio->out = ~n_latch;
gpio->status = gpio->out;
status = gpiochip_add(&gpio->chip);
@ -426,6 +453,7 @@ 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,