gpio: pcf857x: Add OF support

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>

diff --git a/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt b/Documentation/devicetree/bindings/gpio/gpio-pcf857x.txt
new file mode 100644 (file)
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@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 54725a632660e84167b5804d8f2db1189fc25bd0..1535686e74ea9b037e0799b111ccc4ebdb0489e4 100644 (file)
--- 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,