[PATCH v3 2/3] i2c: Implement i2c_get_chip_by_phandle()

[Philip Richard Oberfichtner <pro@denx.de>]

This new function enhances the i2c_get_chip*() toolbox by implementing a
variant that does not require a chip_addr. Instead, the desired device
is pointed to by a phandle.

Signed-off-by: Philip Richard Oberfichtner <pro@denx.de>
---

Notes:
    Changes in v3: none
    Changes in v2: new

 drivers/i2c/i2c-uclass.c | 75 ++++++++++++++++++++++++++++++++++++++++
 include/i2c.h            | 12 +++++++
 2 files changed, 87 insertions(+)

diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index 8867a560bd..5405067861 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -388,6 +388,81 @@ int i2c_get_chip_for_busnum(int busnum, int chip_addr, uint offset_len,
 	return 0;
 }
 
+/* Find and probe I2C bus based on a chip attached to it */
+static int i2c_get_parent_bus(ofnode chip, struct udevice **devp)
+{
+	ofnode node;
+	struct udevice *dev;
+	int ret;
+
+	node = ofnode_get_parent(chip);
+	if (!ofnode_valid(node))
+		return -ENODEV;
+
+	ret = uclass_get_device_by_ofnode(UCLASS_I2C, node, &dev);
+	if (ret) {
+		*devp = NULL;
+		return ret;
+	}
+
+	*devp = dev;
+	return 0;
+}
+
+int i2c_get_chip_by_phandle(const struct udevice *parent, const char *prop_name,
+			    struct udevice **devp)
+{
+	ofnode node;
+	uint phandle;
+	struct udevice *bus, *chip;
+	char *dev_name;
+	int ret;
+
+	debug("%s: Searching I2C chip for phandle \"%s\"\n",
+	      __func__, prop_name);
+
+	dev_name = strdup(prop_name);
+	if (!dev_name) {
+		ret = -ENOMEM;
+		goto err_exit;
+	}
+
+	ret = dev_read_u32(parent, "i2cbcdev", &phandle);
+	if (ret)
+		goto err_exit;
+
+	node = ofnode_get_by_phandle(phandle);
+	if (!ofnode_valid(node)) {
+		ret = -ENODEV;
+		goto err_exit;
+	}
+
+	ret = i2c_get_parent_bus(node, &bus);
+	if (ret)
+		goto err_exit;
+
+	ret = device_bind_driver_to_node(bus, "i2c_generic_chip_drv",
+					 dev_name, node, &chip);
+	if (ret)
+		goto err_exit;
+
+	ret = device_probe(chip);
+	if (ret) {
+		device_unbind(chip);
+		goto err_exit;
+	}
+
+	debug("%s succeeded\n", __func__);
+	*devp = chip;
+	return 0;
+
+err_exit:
+	free(dev_name);
+	debug("%s failed, ret = %d\n", __func__, ret);
+	*devp = NULL;
+	return ret;
+}
+
 int dm_i2c_probe(struct udevice *bus, uint chip_addr, uint chip_flags,
 		 struct udevice **devp)
 {
diff --git a/include/i2c.h b/include/i2c.h
index ef3820eaba..4e59009cd9 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -537,6 +537,18 @@ int i2c_get_chip(struct udevice *bus, uint chip_addr, uint offset_len,
 int i2c_get_chip_for_busnum(int busnum, int chip_addr, uint offset_len,
 			    struct udevice **devp);
 
+/**
+ * i2c_get_chip_by_phandle() - get a device to use to access a chip
+ *			       based on a phandle property pointing to it
+ *
+ * @parent: Parent device containing the phandle pointer
+ * @name:   Name of phandle property in the parent device node
+ * @devp:   Returns pointer to new device or NULL if not found
+ * Return:  0 on success, -ve on failure
+ */
+int i2c_get_chip_by_phandle(const struct udevice *parent, const char *prop_name,
+			    struct udevice **devp);
+
 /**
  * i2c_chip_of_to_plat() - Decode standard I2C platform data
  *
-- 
2.42.0