i2c: move OF helpers into the core

I2C of helpers used to live in of_i2c.c but experience (from SPI) shows
that it is much cleaner to have this in the core. This also removes a
circular dependency between the helpers and the core, and so we can
finally register child nodes in the core instead of doing this manually
in each driver. So, fix the drivers and documentation, too.

[Modified to keep a stub device registration API exposed to drivers in
order to avoid disruption]

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
(cherry picked from commit 687b81d083c082bc1e853032e3a2a54f8c251d27)
Signed-off-by: Mark Brown <broonie@kernel.org>

Conflicts:
	drivers/i2c/busses/i2c-designware-platdrv.c
	drivers/i2c/busses/i2c-imx.c
	drivers/i2c/busses/i2c-stu300.c
	drivers/i2c/busses/i2c-wmt.c
	drivers/of/Kconfig
	drivers/of/Makefile
	drivers/staging/imx-drm/imx-tve.c
	sound/soc/fsl/imx-wm8962.c

2 files changed, 107 insertions, 5 deletions

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 48e31ed69dbf..c00292aa5221 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -23,7 +23,11 @@
    SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
    Jean Delvare <khali@linux-fr.org>
    Mux support by Rodolfo Giometti <giometti@enneenne.com> and
-   Michael Lawnick <michael.lawnick.ext@nsn.com> */
+   Michael Lawnick <michael.lawnick.ext@nsn.com>
+   OF support is copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
+   (based on a previous patch from Jon Smirl <jonsmirl@gmail.com>) and
+   (c) 2013  Wolfram Sang <wsa@the-dreams.de>
+ */
 
 #include <linux/module.h>
 #include <linux/kernel.h>
@@ -35,7 +39,9 @@
 #include <linux/init.h>
 #include <linux/idr.h>
 #include <linux/mutex.h>
+#include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_irq.h>
 #include <linux/completion.h>
 #include <linux/hardirq.h>
 #include <linux/irqflags.h>
@@ -954,6 +960,104 @@ static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
 	up_read(&__i2c_board_lock);
 }
 
+/* OF support code */
+
+#if IS_ENABLED(CONFIG_OF)
+static void internal_of_i2c_register_devices(struct i2c_adapter *adap)
+{
+	void *result;
+	struct device_node *node;
+
+	/* Only register child devices if the adapter has a node pointer set */
+	if (!adap->dev.of_node)
+		return;
+
+	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
+
+	for_each_available_child_of_node(adap->dev.of_node, node) {
+		struct i2c_board_info info = {};
+		struct dev_archdata dev_ad = {};
+		const __be32 *addr;
+		int len;
+
+		dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
+
+		if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
+			dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
+				node->full_name);
+			continue;
+		}
+
+		addr = of_get_property(node, "reg", &len);
+		if (!addr || (len < sizeof(int))) {
+			dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
+				node->full_name);
+			continue;
+		}
+
+		info.addr = be32_to_cpup(addr);
+		if (info.addr > (1 << 10) - 1) {
+			dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
+				info.addr, node->full_name);
+			continue;
+		}
+
+		info.irq = irq_of_parse_and_map(node, 0);
+		info.of_node = of_node_get(node);
+		info.archdata = &dev_ad;
+
+		if (of_get_property(node, "wakeup-source", NULL))
+			info.flags |= I2C_CLIENT_WAKE;
+
+		request_module("%s%s", I2C_MODULE_PREFIX, info.type);
+
+		result = i2c_new_device(adap, &info);
+		if (result == NULL) {
+			dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
+				node->full_name);
+			of_node_put(node);
+			irq_dispose_mapping(info.irq);
+			continue;
+		}
+	}
+}
+
+static int of_dev_node_match(struct device *dev, void *data)
+{
+	return dev->of_node == data;
+}
+
+/* must call put_device() when done with returned i2c_client device */
+struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&i2c_bus_type, NULL, node,
+					 of_dev_node_match);
+	if (!dev)
+		return NULL;
+
+	return i2c_verify_client(dev);
+}
+EXPORT_SYMBOL(of_find_i2c_device_by_node);
+
+/* must call put_device() when done with returned i2c_adapter device */
+struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&i2c_bus_type, NULL, node,
+					 of_dev_node_match);
+	if (!dev)
+		return NULL;
+
+	return i2c_verify_adapter(dev);
+}
+EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
+#else
+static void internal_of_i2c_register_devices(struct i2c_adapter *adap) { }
+#endif /* CONFIG_OF */
+
 static int i2c_do_add_adapter(struct i2c_driver *driver,
 			      struct i2c_adapter *adap)
 {
@@ -1058,6 +1162,8 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 
 exit_recovery:
 	/* create pre-declared device nodes */
+	internal_of_i2c_register_devices(adap);
+
 	if (adap->nr < __i2c_first_dynamic_bus_num)
 		i2c_scan_static_board_info(adap);
 
@@ -1282,7 +1388,6 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 }
 EXPORT_SYMBOL(i2c_del_adapter);
 
-
 /* ------------------------------------------------------------------------- */
 
 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 7409ebb33c47..797e3117bef7 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -25,7 +25,6 @@
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
 #include <linux/of.h>
-#include <linux/of_i2c.h>
 
 /* multiplexer per channel data */
 struct i2c_mux_priv {
@@ -185,8 +184,6 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
 	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
 		 i2c_adapter_id(&priv->adap));
 
-	of_i2c_register_devices(&priv->adap);
-
 	return &priv->adap;
 }
 EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);