[PATCH v6] gpio: pcf857x: Add OF support
Laurent Pinchart
laurent.pinchart+renesas at ideasonboard.com
Sat Sep 21 14:39:49 EDT 2013
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 at ideasonboard.com>
---
.../devicetree/bindings/gpio/gpio-pcf857x.txt | 71 ++++++++++++++++++++++
drivers/gpio/gpio-pcf857x.c | 44 +++++++++++---
2 files changed, 107 insertions(+), 8 deletions(-)
create mode 100644 Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
Changes since v5:
- Renamed pin to line in the DT bindings documentation
- Renamed pins-initial-states DT property to lines-initial-states
Changes since v4:
- Don't try to get ngpio from of_device_id data, we already get it from
i2c_device_id
Changes since v3:
- Get rid of the #ifdef CONFIG_OF in the probe function
- Give DT node priority over platform data
Changes since v2:
- Replace mention about interrupts software configuration in DT bindings
documentation with an explanation of the hardware configuration.
diff --git a/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
new file mode 100644
index 0000000..d63194a
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
@@ -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 at 20 {
+ compatible = "nxp,pcf8575";
+ reg = <0x20>;
+ interrupt-parent = <&irqpin2>;
+ interrupts = <3 0>;
+ gpio-controller;
+ #gpio-cells = <2>;
+ interrupt-controller;
+ #interrupt-cells = <2>;
+ };
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
index 54725a6..1535686 100644
--- a/drivers/gpio/gpio-pcf857x.c
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -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,
--
Regards,
Laurent Pinchart
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