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    SubjectRe: [PATCH 1/7] driver-core : add class iteration api

    Add the following class iteration functions for driver use:
    class_for_each_device
    class_find_device
    class_for_each_child
    class_find_child

    Signed-off-by: Dave Young <hidave.darkstar@gmail.com>

    ---
    drivers/base/class.c | 159 +++++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/device.h | 11 ++-
    2 files changed, 168 insertions(+), 2 deletions(-)

    diff -upr linux/drivers/base/class.c linux.new/drivers/base/class.c
    --- linux/drivers/base/class.c 2008-01-15 11:12:29.000000000 +0800
    +++ linux.new/drivers/base/class.c 2008-01-15 11:12:29.000000000 +0800
    @@ -798,6 +798,165 @@ void class_device_put(struct class_devic
    kobject_put(&class_dev->kobj);
    }

    +/**
    + * class_for_each_device - device iterator
    + * @class: the class we're iterating
    + * @data: data for the callback
    + * @fn: function to be called for each device
    + *
    + * Iterate over @class's list of devices, and call @fn for each,
    + * passing it @data.
    + *
    + * We check the return of @fn each time. If it returns anything
    + * other than 0, we break out and return that value.
    + */
    +int class_for_each_device(struct class *class, void *data,
    + int (*fn)(struct device *, void *))
    +{
    + struct device *dev;
    + int error = 0;
    +
    + if (!class)
    + return -EINVAL;
    + down(&class->sem);
    + list_for_each_entry(dev, &class->devices, node) {
    + dev = get_device(dev);
    + if (dev) {
    + error = fn(dev, data);
    + put_device(dev);
    + } else
    + error = -ENODEV;
    + if (error)
    + break;
    + }
    + up(&class->sem);
    +
    + return error;
    +}
    +EXPORT_SYMBOL_GPL(class_for_each_device);
    +
    +/**
    + * class_find_device - device iterator for locating a particular device
    + * @class: the class we're iterating
    + * @data: data for the match function
    + * @match: function to check device
    + *
    + * This is similar to the class_for_each_dev() function above, but it
    + * returns a reference to a device that is 'found' for later use, as
    + * determined by the @match callback.
    + *
    + * The callback should return 0 if the device doesn't match and non-zero
    + * if it does. If the callback returns non-zero, this function will
    + * return to the caller and not iterate over any more devices.
    +
    + * Note, you will need to drop the reference with put_device() after use.
    + */
    +struct device *class_find_device(struct class *class, void *data,
    + int (*match)(struct device *, void *))
    +{
    + struct device *dev;
    + int found = 0;
    +
    + if (!class)
    + return NULL;
    +
    + down(&class->sem);
    + list_for_each_entry(dev, &class->devices, node) {
    + dev = get_device(dev);
    + if (dev) {
    + if (match(dev, data)) {
    + found = 1;
    + break;
    + } else
    + put_device(dev);
    + } else
    + break;
    + }
    + up(&class->sem);
    +
    + return found ? dev : NULL;
    +}
    +EXPORT_SYMBOL_GPL(class_find_device);
    +
    +/**
    + * class_for_each_child - class child iterator
    + * @class: the class we're iterating
    + * @data: data for the callback
    + * @fn: function to be called for each child of the class
    + *
    + * Iterate over @class's list of children, and call @fn for each,
    + * passing it @data.
    + *
    + * We check the return of @fn each time. If it returns anything
    + * other than 0, we break out and return that value.
    + */
    +int class_for_each_child(struct class *class, void *data,
    + int (*fn)(struct class_device *, void *))
    +{
    + struct class_device *dev;
    + int error = 0;
    +
    + if (!class)
    + return -EINVAL;
    + down(&class->sem);
    + list_for_each_entry(dev, &class->children, node) {
    + dev = class_device_get(dev);
    + if (dev) {
    + error = fn(dev, data);
    + class_device_put(dev);
    + } else
    + error = -ENODEV;
    + if (error)
    + break;
    + }
    + up(&class->sem);
    +
    + return error;
    +}
    +EXPORT_SYMBOL_GPL(class_for_each_child);
    +
    +/**
    + * class_find_child - device iterator for locating a particular class_device
    + * @class: the class we're iterating
    + * @data: data for the match function
    + * @match: function to check class_device
    + *
    + * This is similar to the class_for_each_child() function above, but it
    + * returns a reference to a class_device that is 'found' for later use, as
    + * determined by the @match callback.
    + *
    + * The callback should return 0 if the class_device doesn't match and non-zero
    + * if it does. If the callback returns non-zero, this function will
    + * return to the caller and not iterate over any more class_devices.
    +
    + * Note, you will need to drop the reference with class_device_put() after use.
    + */
    +struct class_device *class_find_child(struct class *class, void *data,
    + int (*match)(struct class_device *, void *))
    +{
    + struct class_device *dev;
    + int found = 0;
    +
    + if (!class)
    + return NULL;
    +
    + down(&class->sem);
    + list_for_each_entry(dev, &class->children, node) {
    + dev = class_device_get(dev);
    + if (dev) {
    + if (match(dev, data)) {
    + found = 1;
    + break;
    + } else
    + class_device_put(dev);
    + } else
    + break;
    + }
    + up(&class->sem);
    +
    + return found ? dev : NULL;
    +}
    +EXPORT_SYMBOL_GPL(class_find_child);

    int class_interface_register(struct class_interface *class_intf)
    {
    diff -upr linux/include/linux/device.h linux.new/include/linux/device.h
    --- linux/include/linux/device.h 2008-01-15 11:12:29.000000000 +0800
    +++ linux.new/include/linux/device.h 2008-01-15 11:12:29.000000000 +0800
    @@ -180,8 +180,7 @@ struct class {
    struct list_head devices;
    struct list_head interfaces;
    struct kset class_dirs;
    - struct semaphore sem; /* locks both the children and interfaces lists */
    -
    + struct semaphore sem; /* locks children, devices, interfaces */
    struct class_attribute * class_attrs;
    struct class_device_attribute * class_dev_attrs;
    struct device_attribute * dev_attrs;
    @@ -199,6 +198,14 @@ struct class {

    extern int __must_check class_register(struct class *);
    extern void class_unregister(struct class *);
    +extern int class_for_each_device(struct class *class, void *data,
    + int (*fn)(struct device *dev, void *data));
    +extern struct device *class_find_device(struct class *class, void *data,
    + int (*match)(struct device *, void *));
    +extern int class_for_each_child(struct class *class, void *data,
    + int (*fn)(struct class_device *, void *));
    +extern struct class_device *class_find_child(struct class *class, void *data,
    + int (*match)(struct class_device *, void *));


    struct class_attribute {

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