[PATCH v1 1/1] mux: Add new API to get mux_control ref by device name.

[sathyanarayanan . kuppuswamy]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

Currently this driver only provides a single API, mux_control_get() to
get mux_control reference based on mux_name, and also this API has tight
dependency on device tree node. For devices, that does not use device
tree, it makes it difficult to use this API. This patch adds new
API to access mux_control reference based on device name, chip index and
controller index value.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
---
 drivers/mux/mux-core.c       | 114 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/mux/consumer.h |   6 ++-
 2 files changed, 119 insertions(+), 1 deletion(-)

diff --git a/drivers/mux/mux-core.c b/drivers/mux/mux-core.c
index 90b8995..f8796b9 100644
--- a/drivers/mux/mux-core.c
+++ b/drivers/mux/mux-core.c
@@ -422,6 +422,87 @@ static struct mux_chip *of_find_mux_chip_by_node(struct device_node *np)
 	return dev ? to_mux_chip(dev) : NULL;
 }
 
+static int dev_parent_name_match(struct device *dev, const void *data)
+{
+	const char *devname = dev_name(dev->parent);
+	unsigned int i;
+
+	if (!devname || !data)
+		return 0;
+
+	for (i = 0; i < strlen(devname); i++) {
+		if (devname[i] == '.')
+			break;
+	}
+
+	return !strncmp(devname, data, i-1);
+}
+
+/**
+ * mux_chip_get_by_index() - Get the mux-chip associated with give device.
+ * @devname: Name of the device which registered the mux-chip.
+ * @index: Index of the mux chip.
+ *
+ * Return: A pointer to the mux-chip, or an ERR_PTR with a negative errno.
+ */
+static struct mux_chip *mux_chip_get_by_index(const char *devname, int index)
+{
+	struct device *dev;
+	int found = -1;
+
+	if (!devname)
+		return ERR_PTR(-EINVAL);
+
+	do {
+		dev = class_find_device(&mux_class, NULL, devname,
+					dev_parent_name_match);
+
+		if (dev != NULL)
+			found++;
+
+		if (found >= index)
+			break;
+	} while (dev != NULL);
+
+	if ((found == index) && dev)
+		return to_mux_chip(dev);
+
+	return ERR_PTR(-ENODEV);
+}
+
+/**
+ * mux_control_get_by_index() - Get the mux-control of given device based on
+ *				device name, chip and control index.
+ * @devname: Name of the device which registered the mux-chip.
+ * @chip_index: Index of the mux chip.
+ * @ctrl_index: Index of the mux controller.
+ *
+ * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *mux_control_get_by_index(const char *devname,
+					     unsigned int chip_index,
+					     unsigned int ctrl_index)
+{
+	struct mux_chip *mux_chip;
+
+	mux_chip = mux_chip_get_by_index(devname, chip_index);
+
+	if (IS_ERR(mux_chip))
+		return ERR_PTR(PTR_ERR(mux_chip));
+
+	if (ctrl_index >= mux_chip->controllers) {
+		dev_err(&mux_chip->dev,
+				"Invalid controller index, maximum value is %d\n",
+				mux_chip->controllers);
+		return ERR_PTR(-EINVAL);
+	}
+
+	get_device(&mux_chip->dev);
+
+	return &mux_chip->mux[ctrl_index];
+}
+EXPORT_SYMBOL_GPL(mux_control_get_by_index);
+
 /**
  * mux_control_get() - Get the mux-control for a device.
  * @dev: The device that needs a mux-control.
@@ -533,6 +614,39 @@ struct mux_control *devm_mux_control_get(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_mux_control_get);
 
+/**
+ * devm_mux_control_get_by_index() - Get the mux-control for a device of given
+ *				     index value.
+ * @dev: The device that needs a mux-control.
+ * @devname: Name of the device which registered the mux-chip.
+ * @chip_index: Index of the mux chip.
+ * @ctrl_index: Index of the mux controller.
+ *
+ * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
+ */
+struct mux_control *devm_mux_control_get_by_index(struct device *dev,
+		const char *devname, unsigned int chip_index,
+		unsigned int ctrl_index)
+{
+	struct mux_control **ptr, *mux;
+
+	ptr = devres_alloc(devm_mux_control_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	mux = mux_control_get_by_index(devname, chip_index, ctrl_index);
+	if (IS_ERR(mux)) {
+		devres_free(ptr);
+		return mux;
+	}
+
+	*ptr = mux;
+	devres_add(dev, ptr);
+
+	return mux;
+}
+EXPORT_SYMBOL_GPL(devm_mux_control_get_by_index);
+
 /*
  * Using subsys_initcall instead of module_init here to try to ensure - for
  * the non-modular case - that the subsystem is initialized when mux consumers
diff --git a/include/linux/mux/consumer.h b/include/linux/mux/consumer.h
index 5577e1b..e02485b 100644
--- a/include/linux/mux/consumer.h
+++ b/include/linux/mux/consumer.h
@@ -28,5 +28,9 @@ void mux_control_put(struct mux_control *mux);
 
 struct mux_control *devm_mux_control_get(struct device *dev,
 					 const char *mux_name);
-
+struct mux_control *mux_control_get_by_index(const char *devname,
+		unsigned int chip_index, unsigned int ctrl_index);
+struct mux_control *devm_mux_control_get_by_index(struct device *dev,
+		const char *devname, unsigned int chip_index,
+		unsigned int ctrl_index);
 #endif /* _LINUX_MUX_CONSUMER_H */
-- 
2.7.4