HID: i2c-hid: add DT bindings

Add device tree based support for HID over I2C devices.

Tested on an Odroid-X board with a Synaptics touchpad.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

3 files changed, 73 insertions, 2 deletions

diff --git a/Documentation/devicetree/bindings/hid/hid-over-i2c.txt b/Documentation/devicetree/bindings/hid/hid-over-i2c.txt
new file mode 100644
index 000000000000..488edcb264c4
--- /dev/null
+++ b/Documentation/devicetree/bindings/hid/hid-over-i2c.txt
@@ -0,0 +1,28 @@
+* HID over I2C Device-Tree bindings
+
+HID over I2C provides support for various Human Interface Devices over the
+I2C bus. These devices can be for example touchpads, keyboards, touch screens
+or sensors.
+
+The specification has been written by Microsoft and is currently available here:
+http://msdn.microsoft.com/en-us/library/windows/hardware/hh852380.aspx
+
+If this binding is used, the kernel module i2c-hid will handle the communication
+with the device and the generic hid core layer will handle the protocol.
+
+Required properties:
+- compatible: must be "hid-over-i2c"
+- reg: i2c slave address
+- hid-descr-addr: HID descriptor address
+- interrupt-parent: the phandle for the interrupt controller
+- interrupts: interrupt line
+
+Example:
+
+        i2c-hid-dev@2c {
+                compatible = "hid-over-i2c";
+                reg = <0x2c>;
+                hid-descr-addr = <0x0020>;
+                interrupt-parent = <&gpx3>;
+                interrupts = <3 2>;
+        };
diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 879b0ed701a3..fc9d92cb3f39 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -35,6 +35,7 @@
 #include <linux/hid.h>
 #include <linux/mutex.h>
 #include <linux/acpi.h>
+#include <linux/of.h>
 
 #include <linux/i2c/i2c-hid.h>
 
@@ -933,6 +934,42 @@ static inline int i2c_hid_acpi_pdata(struct i2c_client *client,
 }
 #endif
 
+#ifdef CONFIG_OF
+static int i2c_hid_of_probe(struct i2c_client *client,
+                struct i2c_hid_platform_data *pdata)
+{
+        struct device *dev = &client->dev;
+        u32 val;
+        int ret;
+
+        ret = of_property_read_u32(dev->of_node, "hid-descr-addr", &val);
+        if (ret) {
+                dev_err(&client->dev, "HID register address not provided\n");
+                return -ENODEV;
+        }
+        if (val >> 16) {
+                dev_err(&client->dev, "Bad HID register address: 0x%08x\n",
+                        val);
+                return -EINVAL;
+        }
+        pdata->hid_descriptor_address = val;
+
+        return 0;
+}
+
+static const struct of_device_id i2c_hid_of_match[] = {
+        { .compatible = "hid-over-i2c" },
+        {},
+};
+MODULE_DEVICE_TABLE(of, i2c_hid_of_match);
+#else
+static inline int i2c_hid_of_probe(struct i2c_client *client,
+                struct i2c_hid_platform_data *pdata)
+{
+        return -ENODEV;
+}
+#endif
+
 static int i2c_hid_probe(struct i2c_client *client,
                          const struct i2c_device_id *dev_id)
 {
@@ -954,7 +991,11 @@ static int i2c_hid_probe(struct i2c_client *client,
         if (!ihid)
                 return -ENOMEM;
 
-        if (!platform_data) {
+        if (client->dev.of_node) {
+                ret = i2c_hid_of_probe(client, &ihid->pdata);
+                if (ret)
+                        goto err;
+        } else if (!platform_data) {
                 ret = i2c_hid_acpi_pdata(client, &ihid->pdata);
                 if (ret) {
                         dev_err(&client->dev,
@@ -1095,6 +1136,7 @@ static struct i2c_driver i2c_hid_driver = {
                 .owner  = THIS_MODULE,
                 .pm     = &i2c_hid_pm,
                 .acpi_match_table = ACPI_PTR(i2c_hid_acpi_match),
+                .of_match_table = of_match_ptr(i2c_hid_of_match),
         },
 
         .probe          = i2c_hid_probe,
diff --git a/include/linux/i2c/i2c-hid.h b/include/linux/i2c/i2c-hid.h
index 60e411d764d4..7aa901d92058 100644
--- a/include/linux/i2c/i2c-hid.h
+++ b/include/linux/i2c/i2c-hid.h
@@ -19,7 +19,8 @@
  * @hid_descriptor_address: i2c register where the HID descriptor is stored.
  *
  * Note that it is the responsibility of the platform driver (or the acpi 5.0
- * driver) to setup the irq related to the gpio in the struct i2c_board_info.
+ * driver, or the flattened device tree) to setup the irq related to the gpio in
+ * the struct i2c_board_info.
  * The platform driver should also setup the gpio according to the device:
  *
  * A typical example is the following: