[RFC PATCH] drivers: phy: add generic PHY framework

[Kishon Vijay Abraham I]

The PHY framework provides a set of API's for the PHY drivers to
create/remove a PHY and the PHY users to obtain a reference to the PHY
using or without using phandle. If the PHY users has to obtain a reference to
the PHY without using phandle, the platform specfic intialization code (say
from board file) should have already called phy_bind with the binding
information. The binding information consists of phy's device name, phy
user device name and an index. The index is used when the same phy user
binds to mulitple phys.

PHY drivers should create the PHY by passing phy_descriptor that has
information about the PHY and ops like init, exit, suspend, resume,
poweron, shutdown.

Nyet-signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
---
This framework is actually intended to be used by all the PHY drivers in the
kernel. Though it's going to take a while for that, I intend to migrate
existing USB/OTG phy drivers to use this framework as we align on the design
of this framework. Once I migrate these phy drivers, I'll be able to test this
framework (I haven't tested this framework so far). I sent this patch early
so as to get review comments and align on the design. Thanks :-)

 drivers/Kconfig         |    2 +
 drivers/Makefile        |    2 +
 drivers/phy/Kconfig     |   13 ++
 drivers/phy/Makefile    |    5 +
 drivers/phy/phy-core.c  |  437 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/phy/phy.h |  181 ++++++++++++++++++++
 6 files changed, 640 insertions(+)
 create mode 100644 drivers/phy/Kconfig
 create mode 100644 drivers/phy/Makefile
 create mode 100644 drivers/phy/phy-core.c
 create mode 100644 include/linux/phy/phy.h

diff --git a/drivers/Kconfig b/drivers/Kconfig
index ece958d..8488818 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -152,4 +152,6 @@ source "drivers/vme/Kconfig"
 
 source "drivers/pwm/Kconfig"
 
+source "drivers/phy/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 5b42184..63d6bbe 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -38,6 +38,8 @@ obj-y				+= char/
 # gpu/ comes after char for AGP vs DRM startup
 obj-y				+= gpu/
 
+obj-y				+= phy/
+
 obj-$(CONFIG_CONNECTOR)		+= connector/
 
 # i810fb and intelfb depend on char/agp/
diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
new file mode 100644
index 0000000..34f7077
--- /dev/null
+++ b/drivers/phy/Kconfig
@@ -0,0 +1,13 @@
+#
+# PHY
+#
+
+menuconfig GENERIC_PHY
+	tristate "Generic PHY Support"
+	help
+	  Generic PHY support.
+
+	  This framework is designed to provide a generic interface for PHY
+	  devices present in the kernel. This layer will have the generic
+	  API by which phy drivers can create PHY using the phy framework and
+	  phy users can obtain reference to the PHY.
diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
new file mode 100644
index 0000000..9e9560f
--- /dev/null
+++ b/drivers/phy/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for the phy drivers.
+#
+
+obj-$(CONFIG_GENERIC_PHY)	+= phy-core.o
diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
new file mode 100644
index 0000000..c55446a
--- /dev/null
+++ b/drivers/phy/phy-core.c
@@ -0,0 +1,437 @@
+/*
+ * phy-core.c  --  Generic Phy framework.
+ *
+ * Copyright (C) 2012 Texas Instruments
+ *
+ * Author: Kishon Vijay Abraham I <kishon@xxxxxx>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+
+static struct class *phy_class;
+static LIST_HEAD(phy_list);
+static DEFINE_MUTEX(phy_list_mutex);
+static LIST_HEAD(phy_bind_list);
+
+static void devm_phy_release(struct device *dev, void *res)
+{
+	struct phy *phy = *(struct phy **)res;
+
+	phy_put(phy);
+}
+
+static int devm_phy_match(struct device *dev, void *res, void *match_data)
+{
+	return res == match_data;
+}
+
+static struct phy *phy_lookup(struct device *dev, u8 index)
+{
+	struct phy_bind *phy_bind = NULL;
+
+	list_for_each_entry(phy_bind, &phy_bind_list, list) {
+		if (!(strcmp(phy_bind->dev_name, dev_name(dev))) &&
+				phy_bind->index == index)
+			return phy_bind->phy;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
+static struct phy *of_phy_lookup(struct device *dev, struct device_node *node)
+{
+	int index = 0;
+	struct phy  *phy;
+	struct phy_bind *phy_map = NULL;
+
+	list_for_each_entry(phy_map, &phy_bind_list, list)
+		if (!(strcmp(phy_map->dev_name, dev_name(dev))))
+			index++;
+
+	list_for_each_entry(phy, &phy_list, head) {
+		if (node != phy->desc->of_node)
+			continue;
+
+		phy_map = phy_bind(dev_name(dev), index, dev_name(&phy->dev));
+		if (!IS_ERR(phy_map)) {
+			phy_map->phy = phy;
+			phy_map->auto_bind = true;
+		}
+
+		return phy;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
+/**
+ * devm_phy_get - lookup and obtain a reference to a phy.
+ * @dev: device that requests this phy
+ * @index: the index of the phy
+ *
+ * Gets the phy using phy_get(), and associates a device with it using
+ * devres. On driver detach, release function is invoked on the devres data,
+ * then, devres data is freed.
+ */
+struct phy *devm_phy_get(struct device *dev, u8 index)
+{
+	struct phy **ptr, *phy;
+
+	ptr = devres_alloc(devm_phy_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	phy = phy_get(dev, index);
+	if (!IS_ERR(phy)) {
+		*ptr = phy;
+		devres_add(dev, ptr);
+	} else
+		devres_free(ptr);
+
+	return phy;
+}
+EXPORT_SYMBOL_GPL(devm_phy_get);
+
+/**
+ * devm_phy_put - release the PHY
+ * @dev: device that wants to release this phy
+ * @phy: the phy returned by devm_phy_get()
+ *
+ * destroys the devres associated with this phy and invokes phy_put
+ * to release the phy.
+ */
+void devm_phy_put(struct device *dev, struct phy *phy)
+{
+	int r;
+
+	r = devres_destroy(dev, devm_phy_release, devm_phy_match, phy);
+	dev_WARN_ONCE(dev, r, "couldn't find PHY resource\n");
+}
+EXPORT_SYMBOL_GPL(devm_phy_put);
+
+/**
+ * devm_of_phy_get - lookup and obtain a reference to a phy by phandle
+ * @dev: device that requests this phy
+ * @phandle: name of the property holding the phy phandle value
+ *
+ * Returns the phy driver associated with the given phandle value,
+ * after getting a refcount to it or -ENODEV if there is no such phy.
+ * While at that, it also associates the device with the phy using devres.
+ * On driver detach, release function is invoked on the devres data,
+ * then, devres data is freed.
+ */
+struct phy *devm_of_phy_get(struct device *dev, const char *phandle)
+{
+	struct phy	*phy = NULL, **ptr;
+	struct device_node *node;
+
+	if (!dev->of_node) {
+		dev_dbg(dev, "device does not have a device node entry\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	node = of_parse_phandle(dev->of_node, phandle, 0);
+	if (!node) {
+		dev_dbg(dev, "failed to get %s phandle in %s node\n", phandle,
+			dev->of_node->full_name);
+		return ERR_PTR(-ENODEV);
+	}
+
+	ptr = devres_alloc(devm_phy_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr) {
+		dev_dbg(dev, "failed to allocate memory for devres\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mutex_lock(&phy_list_mutex);
+
+	phy = of_phy_lookup(dev, node);
+	if (IS_ERR(phy) || !try_module_get(phy->dev.driver->owner)) {
+		devres_free(ptr);
+		goto err0;
+	}
+
+	*ptr = phy;
+	devres_add(dev, ptr);
+
+	get_device(&phy->dev);
+
+err0:
+	mutex_unlock(&phy_list_mutex);
+
+	return phy;
+}
+EXPORT_SYMBOL_GPL(devm_of_phy_get);
+
+/**
+ * phy_get - lookup and obtain a reference to a phy.
+ * @dev: device that requests this phy
+ * @index: the index of the phy
+ *
+ * Returns the phy driver, after getting a refcount to it; or
+ * -ENODEV if there is no such phy.  The caller is responsible for
+ * calling phy_put() to release that count.
+ */
+struct phy *phy_get(struct device *dev, u8 index)
+{
+	struct phy	*phy = NULL;
+
+	mutex_lock(&phy_list_mutex);
+
+	phy = phy_lookup(dev, index);
+	if (IS_ERR(phy)) {
+		pr_err("unable to find phy\n");
+		goto err0;
+	}
+
+	get_device(&phy->dev);
+
+err0:
+	mutex_unlock(&phy_list_mutex);
+
+	return phy;
+}
+EXPORT_SYMBOL_GPL(phy_get);
+
+/**
+ * phy_put - release the PHY
+ * @phy: the phy returned by phy_get()
+ *
+ * Releases a refcount the caller received from phy_get().
+ */
+void phy_put(struct phy *phy)
+{
+	if (phy)
+		put_device(&phy->dev);
+}
+EXPORT_SYMBOL_GPL(phy_put);
+
+/**
+ * create_phy - create a new phy
+ * @dev: device that is creating the new phy
+ * @desc: descriptor of the phy
+ *
+ * Called to create a phy using phy framework.
+ */
+struct phy *create_phy(struct device *dev, struct phy_descriptor *desc)
+{
+	int ret;
+	struct phy *phy;
+	struct phy_bind *phy_bind;
+	const char *devname = NULL;
+
+	if (!dev || !desc) {
+		dev_err(dev, "no descriptor/device provided for PHY\n");
+		ret = -EINVAL;
+		goto err0;
+	}
+
+	if (!desc->ops) {
+		dev_err(dev, "no PHY ops provided\n");
+		ret = -EINVAL;
+		goto err0;
+	}
+
+	phy = kzalloc(sizeof(*phy), GFP_KERNEL);
+	if (!phy) {
+		dev_err(dev, "no memory for PHY\n");
+		ret = -ENOMEM;
+		goto err0;
+	}
+
+	devname = dev_name(dev);
+	device_initialize(&phy->dev);
+	phy->desc = desc;
+	phy->dev.class = phy_class;
+	phy->dev.parent = dev;
+	ret = dev_set_name(&phy->dev, "%s", devname);
+	if (ret)
+		goto err1;
+
+	mutex_lock(&phy_list_mutex);
+	list_for_each_entry(phy_bind, &phy_bind_list, list)
+		if (!(strcmp(phy_bind->phy_dev_name, devname)))
+			phy_bind->phy = phy;
+
+	list_add_tail(&phy->head, &phy_list);
+
+	ret = device_add(&phy->dev);
+	if (ret)
+		goto err2;
+
+	mutex_unlock(&phy_list_mutex);
+
+	return phy;
+
+err2:
+	phy_bind->phy = NULL;
+	list_del(&phy->head);
+	mutex_unlock(&phy_list_mutex);
+
+err1:
+	put_device(&phy->dev);
+	kfree(phy);
+
+err0:
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(create_phy);
+
+/**
+ * destroy_phy - destroy the phy
+ * @phy: the phy to be destroyed
+ *
+ * Called to destroy the phy.
+ */
+void destroy_phy(struct phy *phy)
+{
+	struct phy_bind *phy_bind;
+
+	mutex_lock(&phy_list_mutex);
+	list_for_each_entry(phy_bind, &phy_bind_list, list) {
+		if (phy_bind->phy == phy)
+			phy_bind->phy = NULL;
+
+		if (phy_bind->auto_bind) {
+			list_del(&phy_bind->list);
+			kfree(phy_bind);
+		}
+	}
+
+	list_del(&phy->head);
+	mutex_unlock(&phy_list_mutex);
+
+	device_unregister(&phy->dev);
+}
+EXPORT_SYMBOL_GPL(destroy_phy);
+
+/**
+ * phy_bind - bind the phy and the controller that uses the phy
+ * @dev_name: the device name of the device that will bind to the phy
+ * @index: index to specify the port number
+ * @phy_dev_name: the device name of the phy
+ *
+ * Fills the phy_bind structure with the dev_name and phy_dev_name. This will
+ * be used when the phy driver registers the phy and when the controller
+ * requests this phy.
+ *
+ * To be used by platform specific initialization code.
+ */
+struct phy_bind *phy_bind(const char *dev_name, u8 index,
+				const char *phy_dev_name)
+{
+	struct phy_bind *phy_bind;
+
+	phy_bind = kzalloc(sizeof(*phy_bind), GFP_KERNEL);
+	if (!phy_bind) {
+		pr_err("phy_bind(): No memory for phy_bind");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	phy_bind->dev_name = dev_name;
+	phy_bind->phy_dev_name = phy_dev_name;
+	phy_bind->index = index;
+	phy_bind->auto_bind = false;
+
+	list_add_tail(&phy_bind->list, &phy_bind_list);
+
+	return phy_bind;
+}
+EXPORT_SYMBOL_GPL(phy_bind);
+
+static ssize_t phy_name_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct phy *phy;
+
+	phy = container_of(dev, struct phy, dev);
+
+	return sprintf(buf, "%s\n", phy->desc->label);
+}
+
+static ssize_t phy_bind_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct phy_bind *phy_bind;
+	struct phy *phy;
+	char *p = buf;
+	int len;
+
+	phy = container_of(dev, struct phy, dev);
+
+	list_for_each_entry(phy_bind, &phy_bind_list, list)
+		if (phy_bind->phy == phy)
+			p += sprintf(p, "%s %d\n", phy_bind->dev_name,
+							phy_bind->index);
+	len = (p - buf);
+
+	return len;
+}
+
+static struct device_attribute phy_dev_attrs[] = {
+	__ATTR(label, 0444, phy_name_show, NULL),
+	__ATTR(bind, 0444, phy_bind_show, NULL),
+	__ATTR_NULL,
+};
+
+/**
+ * phy_release - release the phy
+ * @dev: the dev member within phy
+ *
+ * when the last reference to the device is removed; it is called
+ * from the embedded kobject as release method.
+ */
+static void phy_release(struct device *dev)
+{
+	struct phy *phy;
+
+	phy = container_of(dev, struct phy, dev);
+	dev_dbg(dev, "releasing '%s'\n", dev_name(dev));
+	kfree(phy);
+}
+
+static int __init phy_core_init(void)
+{
+	phy_class = class_create(THIS_MODULE, "phy");
+	if (IS_ERR(phy_class)) {
+		pr_err("failed to create phy class --> %ld\n",
+			PTR_ERR(phy_class));
+		return PTR_ERR(phy_class);
+	}
+
+	phy_class->dev_release = phy_release;
+	phy_class->dev_attrs = phy_dev_attrs;
+
+	return 0;
+}
+subsys_initcall(phy_core_init);
+
+static void __exit phy_core_exit(void)
+{
+	class_destroy(phy_class);
+}
+module_exit(phy_core_exit);
+
+MODULE_DESCRIPTION("Generic Phy Framework");
+MODULE_AUTHOR("Kishon Vijay Abraham I <kishon@xxxxxx>");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
new file mode 100644
index 0000000..831c1c0
--- /dev/null
+++ b/include/linux/phy/phy.h
@@ -0,0 +1,181 @@
+/*
+ * phy.h -- generic phy header file
+ *
+ * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Author: Kishon Vijay Abraham I <kishon@xxxxxx>
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __DRIVERS_PHY_H
+#define __DRIVERS_PHY_H
+
+struct phy;
+
+/**
+ * struct phy_descriptor - structure that describes the PHY
+ * @label: label given to phy
+ * @type: specifies the phy type
+ * @of_node: device node of the phy
+ * @ops: function pointers for performing phy operations
+ */
+struct phy_descriptor {
+	const char		*label;
+	int			type;
+	struct device_node	*of_node;
+	struct phy_ops		*ops;
+};
+
+/**
+ * struct phy_ops - set of function pointers for performing phy operations
+ * @init: operation to be performed for initializing phy
+ * @exit: operation to be performed while exiting
+ * @suspend: suspending the phy
+ * @resume: resuming the phy
+ * @poweron: powering on the phy
+ * @shutdown: shutting down the phy
+ */
+struct phy_ops {
+	int	(*init)(struct phy_descriptor *desc);
+	int	(*exit)(struct phy_descriptor *desc);
+	int	(*suspend)(struct phy_descriptor *desc);
+	int	(*resume)(struct phy_descriptor *desc);
+	int	(*poweron)(struct phy_descriptor *desc);
+	int	(*shutdown)(struct phy_descriptor *desc);
+};
+
+/**
+ * struct phy - represent the phy device
+ * @desc: descriptor for the phy
+ * @head: to support multiple transceivers
+ */
+struct phy {
+	struct device		dev;
+	struct phy_descriptor	*desc;
+	struct list_head	head;
+};
+
+/**
+ * struct phy_bind - represent the binding for the phy
+ * @dev_name: the device name of the device that will bind to the phy
+ * @phy_dev_name: the device name of the phy
+ * @index: used if a single controller uses multiple phys
+ * @auto_bind: tells if the binding is done explicitly from board file or not
+ * @phy: reference to the phy
+ * @list: to maintain a linked list of the binding information
+ */
+struct phy_bind {
+	const char	*dev_name;
+	const char	*phy_dev_name;
+	u8		index;
+	int		auto_bind:1;
+	struct phy	*phy;
+	struct list_head list;
+};
+
+#if defined(CONFIG_GENERIC_PHY) || defined(CONFIG_GENERIC_PHY_MODULE)
+extern struct phy *devm_phy_get(struct device *dev, u8 index);
+extern void devm_phy_put(struct device *dev, struct phy *phy);
+extern struct phy *devm_of_phy_get(struct device *dev, const char *phandle);
+extern struct phy *phy_get(struct device *dev, u8 index);
+extern void phy_put(struct phy *phy);
+extern struct phy *create_phy(struct device *dev, struct phy_descriptor *desc);
+extern void destroy_phy(struct phy *phy);
+extern struct phy_bind *phy_bind(const char *dev_name, u8 index,
+				const char *phy_dev_name);
+#else
+static inline struct phy *devm_phy_get(struct device *dev, u8 index)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void devm_phy_put(struct device *dev, struct phy *phy)
+{
+}
+
+static inline struct phy *devm_of_phy_get(struct device *dev,
+		const char *phandle)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline struct phy *phy_get(struct device *dev, u8 index)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void phy_put(struct phy *phy)
+{
+}
+
+static inline struct phy *create_phy(struct device *dev,
+	struct phy_descriptor *desc)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void destroy_phy(struct phy *phy)
+{
+}
+
+static inline struct phy_bind *phy_bind(const char *dev_name, u8 index,
+				const char *phy_dev_name)
+{
+}
+#endif
+
+static inline int phy_init(struct phy *phy)
+{
+	if (phy->desc->ops->init)
+		return phy->desc->ops->init(phy->desc);
+
+	return -EINVAL;
+}
+
+static inline int phy_exit(struct phy *phy)
+{
+	if (phy->desc->ops->exit)
+		return phy->desc->ops->exit(phy->desc);
+
+	return -EINVAL;
+}
+
+static inline int phy_suspend(struct phy *phy)
+{
+	if (phy->desc->ops->suspend)
+		return phy->desc->ops->suspend(phy->desc);
+
+	return -EINVAL;
+}
+
+static inline int phy_resume(struct phy *phy)
+{
+	if (phy->desc->ops->resume)
+		return phy->desc->ops->resume(phy->desc);
+
+	return -EINVAL;
+}
+
+static inline int phy_poweron(struct phy *phy)
+{
+	if (phy->desc->ops->poweron)
+		return phy->desc->ops->poweron(phy->desc);
+
+	return -EINVAL;
+}
+
+static inline void phy_shutdown(struct phy *phy)
+{
+	if (phy->desc->ops->shutdown)
+		phy->desc->ops->shutdown(phy->desc);
+}
+#endif /* __DRIVERS_PHY_H */
-- 
1.7.9.5

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