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    Subject[PATCH v5 3/5] Extcon: support multiple states at a device.
    Date
    One switch device (e.g., MUIC(MAX8997, MAX77686, ...), and some 30-pin
    devices) may have multiple cables attached. For example, one
    30-pin port may inhabit a USB cable, an HDMI cable, and a mic.
    Thus, one switch device requires multiple state bits each representing
    a type of cable.

    For such purpose, we use the 32bit state variable; thus, up to 32
    different type of cables may be defined for a switch device. The list of
    possible cables is defined by the array of cable names in the switch_dev
    struct given to the class.

    Signed-off-by: Donggeun Kim <dg77.kim@samsung.com>
    Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
    Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

    --
    Changes from V4
    - Bugfixes after more testing at Exynos4412 boards with userspace
    processses.

    Changes from V3
    - Bugfixes after more testing at Exynos4412 boards.

    Changes from V2
    - State can be stored by user
    - Documentation updated

    Changes from RFC
    - Switch is renamed to extcon
    - Added kerneldoc comments
    - Added APIs to support "standard" cable names
    - Added helper APIs to support notifier block registration with cable
    name.
    - Regrouped function list in the header file.

    Extcon: extcon framework bugfix

    This patch fixes the following issues:
    1. NULL pointer error due to device_attribute
    2. The message of 'BUG: sleeping function called from invalid context ...'
    is shown when calling get_zeroed_page in spin locked
    3. Handling old state had bug that not properly interpretting the
    semantics of values.
    4. Incorrect sysfs node format (state)

    Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
    ---
    Documentation/ABI/testing/sysfs-class-extcon | 38 +++-
    drivers/extcon/extcon_class.c | 310 ++++++++++++++++++++++++-
    include/linux/extcon.h | 151 +++++++++++++
    3 files changed, 482 insertions(+), 17 deletions(-)

    diff --git a/Documentation/ABI/testing/sysfs-class-extcon b/Documentation/ABI/testing/sysfs-class-extcon
    index 59a4b1c..31bb609 100644
    --- a/Documentation/ABI/testing/sysfs-class-extcon
    +++ b/Documentation/ABI/testing/sysfs-class-extcon
    @@ -7,6 +7,14 @@ Description:
    The name of extcon object denoted as ... is the name given
    with extcon_dev_register.

    + One extcon device denotes a single external connector
    + port. An external connector may have multiple cables
    + attached simultaneously. Many of docks, cradles, and
    + accessory cables have such capability. For example,
    + the 30-pin port of Nuri board (/arch/arm/mach-exynos)
    + may have both HDMI and Charger attached, or analog audio,
    + video, and USB cables attached simulteneously.
    +
    What: /sys/class/extcon/.../name
    Date: December 2011
    Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
    @@ -20,7 +28,29 @@ What: /sys/class/extcon/.../state
    Date: December 2011
    Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
    Description:
    - The /sys/class/extcon/.../state shows the cable attach/detach
    - information of the corresponding extcon object. If the extcon
    - objecct has an optional callback "show_state" defined, the
    - callback will provide the name with this sysfs node.
    + The /sys/class/extcon/.../state shows and stores the cable
    + attach/detach information of the corresponding extcon object.
    + If the extcon objecct has an optional callback "show_state"
    + defined, the showing function is overriden with the optional
    + callback.
    +
    + If the default callback for showing function is used, the
    + format is like this:
    + # cat state
    + USB_OTG=1
    + HDMI=0
    + TA=1
    + EAR_JACK=0
    + #
    + In this example, the extcon device have USB_OTG and TA
    + cables attached and HDMI and EAR_JACK cables detached.
    +
    + There are two methods to update state of extcon.
    + Method 1.
    + echo CABLE_NAME [0|1] > state
    + Method 2.
    + echo 0xHEX > state
    +
    + Method 1 updates the state (0 or 1) of the
    + corresponding cable (either the name or index of the cable).
    + Method 2 updates the whole state of the extcon dev.
    diff --git a/drivers/extcon/extcon_class.c b/drivers/extcon/extcon_class.c
    index 763cf4d..2803bd0 100644
    --- a/drivers/extcon/extcon_class.c
    +++ b/drivers/extcon/extcon_class.c
    @@ -31,6 +31,25 @@
    #include <linux/extcon.h>
    #include <linux/slab.h>

    +const char *extcon_cable_name[] = {
    + [EXTCON_USB] = "USB",
    + [EXTCON_USB_HOST] = "USB-Host",
    + [EXTCON_TA] = "TA",
    + [EXTCON_FAST_CHARGER] = "Fast-charger",
    + [EXTCON_SLOW_CHARGER] = "Slow-charger",
    + [EXTCON_CHARGE_DOWNSTREAM] = "Charge-downstream",
    + [EXTCON_HDMI] = "HDMI",
    + [EXTCON_MHL] = "MHL",
    + [EXTCON_DVI] = "DVI",
    + [EXTCON_VGA] = "VGA",
    + [EXTCON_DOCK] = "Dock",
    + [EXTCON_AUDIO_IN] = "Audio-in",
    + [EXTCON_AUDIO_OUT] = "Audio-out",
    + [EXTCON_VIDEO_IN] = "Video-in",
    + [EXTCON_VIDEO_OUT] = "Video-out",
    +
    + NULL,
    +};
    struct class *extcon_class;
    struct class *extcon_class_for_android;

    @@ -40,6 +59,7 @@ static DEFINE_MUTEX(extcon_dev_list_lock);
    static ssize_t state_show(struct device *dev, struct device_attribute *attr,
    char *buf)
    {
    + int i, count = 0;
    struct extcon_dev *edev = (struct extcon_dev *) dev_get_drvdata(dev);

    if (edev->print_state) {
    @@ -49,7 +69,55 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
    return ret;
    /* Use default if failed */
    }
    - return sprintf(buf, "%u\n", edev->state);
    +
    + if (edev->max_supported == 0)
    + return sprintf(buf, "%u\n", edev->state);
    +
    + for (i = 0; i < SUPPORTED_CABLE_MAX; i++) {
    + if (!edev->supported_cable[i])
    + break;
    + count += sprintf(buf + count, "%s=%d\n",
    + edev->supported_cable[i],
    + !!(edev->state & (1 << i)));
    + }
    +
    + return count;
    +}
    +
    +void extcon_set_state(struct extcon_dev *edev, u32 state);
    +static ssize_t state_store(struct device *dev, struct device_attribute *attr,
    + const char *buf, size_t count)
    +{
    + u32 state;
    + ssize_t ret = 0;
    + int enabled;
    + char *buffer = kzalloc(count + 1, GFP_KERNEL);
    + struct extcon_dev *edev = (struct extcon_dev *) dev_get_drvdata(dev);
    +
    + /* Format: /Documentation/ABI/testing/sysfs-class-extcon */
    + ret = sscanf(buf, "%s %d", buffer, &enabled);
    +
    + /* TODO: remove before submit */
    + pr_info("[%s][%d]\n", buffer, enabled);
    +
    + if (ret == 2) {
    + /* Method 1 */
    + ret = extcon_set_cable_state(edev, buffer, enabled);
    + pr_info("Method 1\n");
    + } else if (ret == 1) {
    + /* Method 2 */
    + ret = sscanf(buf, "0x%x", &state);
    + pr_info("Method 2 with 0x%x\n", state);
    + if (ret == 0)
    + ret = -EINVAL;
    + else
    + extcon_set_state(edev, state);
    + } else {
    + ret = -EINVAL;
    + }
    +
    + kfree(buffer);
    + return ret;
    }

    static ssize_t name_show(struct device *dev, struct device_attribute *attr,
    @@ -68,8 +136,10 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
    }

    /**
    - * extcon_set_state() - Set the cable attach states of the extcon device.
    + * extcon_update_state() - Update the cable attach states of the extcon device
    + * only for the masked bits.
    * @edev: the extcon device
    + * @mask: the bit mask to designate updated bits.
    * @state: new cable attach status for @edev
    *
    * Changing the state sends uevent with environment variable containing
    @@ -77,10 +147,10 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
    * Tizen uses this format for extcon device to get events from ports.
    * Android uses this format as well.
    *
    - * Note that notifier provides the which bits are changes in the state
    - * variable with "val" to the callback.
    + * Note that the notifier provides which bits are changed in the state
    + * variable with the val parameter (second) to the callback.
    */
    -void extcon_set_state(struct extcon_dev *edev, u32 state)
    +void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
    {
    char name_buf[120];
    char state_buf[120];
    @@ -88,15 +158,20 @@ void extcon_set_state(struct extcon_dev *edev, u32 state)
    char *envp[3];
    int env_offset = 0;
    int length;
    - u32 old_state = edev->state;
    + unsigned long flags;

    - if (edev->state != state) {
    - edev->state = state;
    + spin_lock_irqsave(&edev->lock, flags);

    - raw_notifier_call_chain(&edev->nh, old_state ^ edev->state,
    - edev);
    + if (edev->state != ((edev->state & ~mask) | (state & mask))) {
    + u32 old_state = edev->state;

    - prop_buf = (char *)get_zeroed_page(GFP_KERNEL);
    + edev->state &= ~mask;
    + edev->state |= state & mask;
    +
    + raw_notifier_call_chain(&edev->nh, old_state, edev);
    +
    + /* This could be in interrupt handler */
    + prop_buf = (char *)get_zeroed_page(GFP_ATOMIC);
    if (prop_buf) {
    length = name_show(edev->dev, NULL, prop_buf);
    if (length > 0) {
    @@ -115,17 +190,132 @@ void extcon_set_state(struct extcon_dev *edev, u32 state)
    envp[env_offset++] = state_buf;
    }
    envp[env_offset] = NULL;
    + /* Unlock early before uevent */
    + spin_unlock_irqrestore(&edev->lock, flags);
    +
    kobject_uevent_env(&edev->dev->kobj, KOBJ_CHANGE, envp);
    free_page((unsigned long)prop_buf);
    } else {
    + /* Unlock early before uevent */
    + spin_unlock_irqrestore(&edev->lock, flags);
    +
    dev_err(edev->dev, "out of memory in extcon_set_state\n");
    kobject_uevent(&edev->dev->kobj, KOBJ_CHANGE);
    }
    + } else {
    + /* No changes */
    + spin_unlock_irqrestore(&edev->lock, flags);
    }
    }
    +EXPORT_SYMBOL_GPL(extcon_update_state);
    +
    +/**
    + * extcon_set_state() - Set the cable attach states of the extcon device.
    + * @edev: the extcon device
    + * @state: new cable attach status for @edev
    + *
    + * Note that notifier provides which bits are changed in the state
    + * variable with the val parameter (second) to the callback.
    + */
    +void extcon_set_state(struct extcon_dev *edev, u32 state)
    +{
    + extcon_update_state(edev, 0xffffffff, state);
    +}
    EXPORT_SYMBOL_GPL(extcon_set_state);

    /**
    + * extcon_find_cable_index() - Get the cable index based on the cable name.
    + * @edev: the extcon device that has the cable.
    + * @cable_name: cable name to be searched.
    + *
    + * Note that accessing a cable state based on cable_index is faster than
    + * cable_name because using cable_name induces a loop with strncmp().
    + * Thus, when get/set_cable_state is repeatedly used, using cable_index
    + * is recommended.
    + */
    +int extcon_find_cable_index(struct extcon_dev *edev, const char *cable_name)
    +{
    + int i;
    +
    + if (edev->supported_cable) {
    + for (i = 0; edev->supported_cable[i]; i++) {
    + if (!strncmp(edev->supported_cable[i],
    + cable_name, CABLE_NAME_MAX))
    + return i;
    + }
    + }
    +
    + return -EINVAL;
    +}
    +EXPORT_SYMBOL_GPL(extcon_find_cable_index);
    +
    +/**
    + * extcon_get_cable_state_() - Get the status of a specific cable.
    + * @edev: the extcon device that has the cable.
    + * @index: cable index that can be retrieved by extcon_find_cable_index().
    + */
    +int extcon_get_cable_state_(struct extcon_dev *edev, int index)
    +{
    + if (index < 0 || (edev->max_supported && edev->max_supported <= index))
    + return -EINVAL;
    +
    + return !!(edev->state & (1 << index));
    +}
    +EXPORT_SYMBOL_GPL(extcon_get_cable_state_);
    +
    +/**
    + * extcon_get_cable_state() - Get the status of a specific cable.
    + * @edev: the extcon device that has the cable.
    + * @cable_name: cable name.
    + *
    + * Note that this is slower than extcon_get_cable_state_.
    + */
    +int extcon_get_cable_state(struct extcon_dev *edev, const char *cable_name)
    +{
    + return extcon_get_cable_state_(edev, extcon_find_cable_index
    + (edev, cable_name));
    +}
    +EXPORT_SYMBOL_GPL(extcon_get_cable_state);
    +
    +/**
    + * extcon_get_cable_state_() - Set the status of a specific cable.
    + * @edev: the extcon device that has the cable.
    + * @index: cable index that can be retrieved by extcon_find_cable_index().
    + * @cable_state: the new cable status. The default semantics is
    + * true: attached / false: detached.
    + */
    +int extcon_set_cable_state_(struct extcon_dev *edev,
    + int index, bool cable_state)
    +{
    + u32 state;
    +
    + if (index < 0 || (edev->max_supported && edev->max_supported <= index))
    + return -EINVAL;
    +
    + state = cable_state ? (1 << index) : 0;
    + extcon_update_state(edev, 1 << index, state);
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(extcon_set_cable_state_);
    +
    +/**
    + * extcon_get_cable_state() - Set the status of a specific cable.
    + * @edev: the extcon device that has the cable.
    + * @cable_name: cable name.
    + * @cable_state: the new cable status. The default semantics is
    + * true: attached / false: detached.
    + *
    + * Note that this is slower than extcon_set_cable_state_.
    + */
    +int extcon_set_cable_state(struct extcon_dev *edev,
    + const char *cable_name, bool cable_state)
    +{
    + return extcon_set_cable_state_(edev, extcon_find_cable_index
    + (edev, cable_name), cable_state);
    +}
    +EXPORT_SYMBOL_GPL(extcon_set_cable_state);
    +
    +/**
    * extcon_get_extcon_dev() - Get the extcon device instance from the name
    * @extcon_name: The extcon name provided with extcon_dev_register()
    */
    @@ -145,11 +335,88 @@ out:
    }
    EXPORT_SYMBOL_GPL(extcon_get_extcon_dev);

    +static int _call_per_cable(struct notifier_block *nb, unsigned long val,
    + void *ptr)
    +{
    + struct extcon_specific_cable_nb *obj = container_of(nb,
    + struct extcon_specific_cable_nb, internal_nb);
    + struct extcon_dev *edev = ptr;
    +
    + if ((val & (1 << obj->cable_index)) !=
    + (edev->state & (1 << obj->cable_index))) {
    + obj->previous_value = val;
    + return obj->user_nb->notifier_call(nb, val, ptr);
    + }
    +
    + return NOTIFY_OK;
    +}
    +
    +/**
    + * extcon_register_interest() - Register a notifier for a state change of a
    + * specific cable, not a entier set of cables of a
    + * extcon device.
    + * @obj: an empty extcon_specific_cable_nb object to be returned.
    + * @extcon_name: the name of extcon device.
    + * @cable_name: the target cable name.
    + * @nb: the notifier block to get notified.
    + *
    + * Provide an empty extcon_specific_cable_nb. extcon_register_interest() sets
    + * the struct for you.
    + *
    + * extcon_register_interest is a helper function for those who want to get
    + * notification for a single specific cable's status change. If a user wants
    + * to get notification for any changes of all cables of a extcon device,
    + * he/she should use the general extcon_register_notifier().
    + *
    + * Note that the second parameter given to the callback of nb (val) is
    + * "old_state", not the current state. The current state can be retrieved
    + * by looking at the third pameter (edev pointer)'s state value.
    + */
    +int extcon_register_interest(struct extcon_specific_cable_nb *obj,
    + const char *extcon_name, const char *cable_name,
    + struct notifier_block *nb)
    +{
    + if (!obj || !extcon_name || !cable_name || !nb)
    + return -EINVAL;
    +
    + obj->edev = extcon_get_extcon_dev(extcon_name);
    + if (!obj->edev)
    + return -ENODEV;
    +
    + obj->cable_index = extcon_find_cable_index(obj->edev, cable_name);
    + if (obj->cable_index < 0)
    + return -ENODEV;
    +
    + obj->user_nb = nb;
    +
    + obj->internal_nb.notifier_call = _call_per_cable;
    +
    + return raw_notifier_chain_register(&obj->edev->nh, &obj->internal_nb);
    +}
    +
    +/**
    + * extcon_unregister_interest() - Unregister the notifier registered by
    + * extcon_register_interest().
    + * @obj: the extcon_specific_cable_nb object returned by
    + * extcon_register_interest().
    + */
    +int extcon_unregister_interest(struct extcon_specific_cable_nb *obj)
    +{
    + if (!obj)
    + return -EINVAL;
    +
    + return raw_notifier_chain_unregister(&obj->edev->nh, &obj->internal_nb);
    +}
    +
    /**
    * extcon_register_notifier() - Register a notifee to get notified by
    * any attach status changes from the extcon.
    * @edev: the extcon device.
    * @nb: a notifier block to be registered.
    + *
    + * Note that the second parameter given to the callback of nb (val) is
    + * "old_state", not the current state. The current state can be retrieved
    + * by looking at the third pameter (edev pointer)'s state value.
    */
    int extcon_register_notifier(struct extcon_dev *edev,
    struct notifier_block *nb)
    @@ -171,8 +438,9 @@ int extcon_unregister_notifier(struct extcon_dev *edev,
    EXPORT_SYMBOL_GPL(extcon_unregister_notifier);

    static struct device_attribute extcon_attrs[] = {
    - __ATTR_RO(state),
    + __ATTR(state, S_IRUGO | S_IWUSR, state_show, state_store),
    __ATTR_RO(name),
    + __ATTR_NULL,
    };

    static int create_extcon_class(void)
    @@ -231,7 +499,7 @@ static void extcon_dev_release(struct device *dev)
    */
    int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
    {
    - int ret;
    + int ret, index = 0;

    if (!extcon_class && !edev->use_class_name_switch) {
    ret = create_extcon_class();
    @@ -244,6 +512,20 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
    return ret;
    }

    + if (edev->supported_cable) {
    + /* Get size of array */
    + for (index = 0; edev->supported_cable[index]; index++)
    + ;
    + edev->max_supported = index;
    + } else {
    + edev->max_supported = 0;
    + }
    +
    + if (index > SUPPORTED_CABLE_MAX) {
    + dev_err(edev->dev, "extcon: maximum number of supported cables exceeded.\n");
    + return -EINVAL;
    + }
    +
    edev->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
    edev->dev->parent = dev;
    if (edev->use_class_name_switch)
    @@ -259,6 +541,8 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
    goto err_dev;
    }

    + spin_lock_init(&edev->lock);
    +
    RAW_INIT_NOTIFIER_HEAD(&edev->nh);

    dev_set_drvdata(edev->dev, edev);
    diff --git a/include/linux/extcon.h b/include/linux/extcon.h
    index 1e47e3b..4384d8f 100644
    --- a/include/linux/extcon.h
    +++ b/include/linux/extcon.h
    @@ -24,6 +24,47 @@
    #define __LINUX_EXTCON_H__

    #include <linux/notifier.h>
    +
    +#define SUPPORTED_CABLE_MAX 32
    +#define CABLE_NAME_MAX 30
    +
    +/*
    + * The standard cable name is to help support general notifier
    + * and notifee device drivers to share the common names.
    + * Please use standard cable names unless your notifier device has
    + * a very unique and abnormal cable or
    + * the cable type is supposed to be used with only one unique
    + * pair of notifier/notifee devices.
    + *
    + * Please add any other "standard" cables used with extcon dev.
    + *
    + * You may add a dot and number to specify version or specification
    + * of the specific cable if it is required. (e.g., "Fast-charger.18"
    + * and "Fast-charger.10" for 1.8A and 1.0A chargers)
    + * However, the notifee and notifier should be able to handle such
    + * string and if the notifee can negotiate the protocol or idenify,
    + * you don't need such convention. This convention is helpful when
    + * notifier can distinguish but notifiee cannot.
    + */
    +enum extcon_cable_name {
    + EXTCON_USB = 0,
    + EXTCON_USB_HOST,
    + EXTCON_TA, /* Travel Adaptor */
    + EXTCON_FAST_CHARGER,
    + EXTCON_SLOW_CHARGER,
    + EXTCON_CHARGE_DOWNSTREAM, /* Charging an external device */
    + EXTCON_HDMI,
    + EXTCON_MHL,
    + EXTCON_DVI,
    + EXTCON_VGA,
    + EXTCON_DOCK,
    + EXTCON_AUDIO_IN,
    + EXTCON_AUDIO_OUT,
    + EXTCON_VIDEO_IN,
    + EXTCON_VIDEO_OUT,
    +};
    +extern const char *extcon_cable_name[];
    +
    /**
    * struct extcon_dev - An extcon device represents one external connector.
    * @name The name of this extcon device. Parent device name is used
    @@ -31,6 +72,9 @@
    * @use_class_name_switch set true in order to be compatible with
    * Android platform, which uses "switch"
    * for the class name.
    + * @supported_cable Array of supported cable name ending with NULL.
    + * If supported_cable is NULL, cable name related APIs
    + * are disabled.
    * @print_name An optional callback to override the method to print the
    * name of the extcon device.
    * @print_state An optional callback to override the method to print the
    @@ -41,6 +85,8 @@
    * @nh Notifier for the state change events from this extcon
    * @entry To support list of extcon devices so that uses can search
    * for extcon devices based on the extcon name.
    + * @lock
    + * @max_supported Internal value to store the number of cables.
    *
    * In most cases, users only need to provide "User initializing data" of
    * this struct when registering an extcon. In some exceptional cases,
    @@ -51,6 +97,7 @@ struct extcon_dev {
    /* --- Optional user initializing data --- */
    const char *name;
    bool use_class_name_switch;
    + const char **supported_cable;

    /* --- Optional callbacks to override class functions --- */
    ssize_t (*print_name)(struct extcon_dev *edev, char *buf);
    @@ -61,6 +108,8 @@ struct extcon_dev {
    u32 state;
    struct raw_notifier_head nh;
    struct list_head entry;
    + spinlock_t lock; /* could be called by irq handler */
    + int max_supported;
    };

    /**
    @@ -81,6 +130,23 @@ struct gpio_extcon_platform_data {
    const char *state_off;
    };

    +/**
    + * struct extcon_specific_cable_nb - An internal data for
    + * extcon_register_interest().
    + * @internal_nb a notifier block bridging extcon notifier and cable notifier.
    + * @user_nb user provided notifier block for events from a specific cable.
    + * @cable_index the target cable.
    + * @edev the target extcon device.
    + * @previous_value the saved previous event value.
    + */
    +struct extcon_specific_cable_nb {
    + struct notifier_block internal_nb;
    + struct notifier_block *user_nb;
    + int cable_index;
    + struct extcon_dev *edev;
    + unsigned long previous_value;
    +};
    +
    #ifdef CONFIG_EXTCON

    /*
    @@ -91,16 +157,54 @@ extern int extcon_dev_register(struct extcon_dev *edev, struct device *dev);
    extern void extcon_dev_unregister(struct extcon_dev *edev);
    extern struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name);

    +/*
    + * get/set/update_state access the 32b encoded state value, which represents
    + * states of all possible cables of the multistate port. For example, if one
    + * calls extcon_set_state(edev, 0x7), it may mean that all the three cables
    + * are attached to the port.
    + */
    static inline u32 extcon_get_state(struct extcon_dev *edev)
    {
    return edev->state;
    }

    extern void extcon_set_state(struct extcon_dev *edev, u32 state);
    +extern void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state);
    +
    +/*
    + * get/set_cable_state access each bit of the 32b encoded state value.
    + * They are used to access the status of each cable based on the cable_name
    + * or cable_index, which is retrived by extcon_find_cable_index
    + */
    +extern int extcon_find_cable_index(struct extcon_dev *sdev,
    + const char *cable_name);
    +extern int extcon_get_cable_state_(struct extcon_dev *edev, int cable_index);
    +extern int extcon_set_cable_state_(struct extcon_dev *edev, int cable_index,
    + bool cable_state);
    +
    +extern int extcon_get_cable_state(struct extcon_dev *edev,
    + const char *cable_name);
    +extern int extcon_set_cable_state(struct extcon_dev *edev,
    + const char *cable_name, bool cable_state);
    +
    +/*
    + * Following APIs are for notifiees (those who want to be notified)
    + * to register a callback for events from a specific cable of the extcon.
    + * Notifiees are the connected device drivers wanting to get notified by
    + * a specific external port of a connection device.
    + */
    +extern int extcon_register_interest(struct extcon_specific_cable_nb *obj,
    + const char *extcon_name,
    + const char *cable_name,
    + struct notifier_block *nb);
    +extern int extcon_unregister_interest(struct extcon_specific_cable_nb *nb);

    /*
    * Following APIs are to monitor every action of a notifier.
    * Registerer gets notified for every external port of a connection device.
    + * Probably this could be used to debug an action of notifier; however,
    + * we do not recommend to use this at normal 'notifiee' device drivers who
    + * want to be notified by a specific external port of the notifier.
    */
    extern int extcon_register_notifier(struct extcon_dev *edev,
    struct notifier_block *nb);
    @@ -121,6 +225,41 @@ static inline u32 extcon_get_state(struct extcon_dev *edev)
    }

    static inline void extcon_set_state(struct extcon_dev *edev, u32 state) { }
    +
    +static inline void extcon_update_state(struct extcon_dev *edev, u32 mask,
    + u32 state)
    +{ }
    +
    +static inline int extcon_find_cable_index(struct extcon_dev *edev,
    + const char *cable_name)
    +{
    + return 0;
    +}
    +
    +static inline int extcon_get_cable_state_(struct extcon_dev *edev,
    + int cable_index)
    +{
    + return 0;
    +}
    +
    +static inline int extcon_set_cable_state_(struct extcon_dev *edev,
    + int cable_index, bool cable_state)
    +{
    + return 0;
    +}
    +
    +static inline int extcon_get_cable_state(struct extcon_dev *edev,
    + const char *cable_name)
    +{
    + return 0;
    +}
    +
    +static inline int extcon_set_cable_state(struct extcon_dev *edev,
    + const char *cable_name, int state)
    +{
    + return 0;
    +}
    +
    static inline struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
    {
    return NULL;
    @@ -138,5 +277,17 @@ static inline int extcon_unregister_notifier(struct extcon_dev *edev,
    return 0;
    }

    +static inline int extcon_register_interest(struct extcon_specific_cable_nb *obj,
    + const char *extcon_name,
    + const char *cable_name,
    + struct notifier_block *nb)
    +{
    + return 0;
    +}
    +
    +static inline int extcon_unregister_interest(struct extcon_specific_cable_nb *)
    +{
    + return 0;
    +}
    #endif /* CONFIG_EXTCON */
    #endif /* __LINUX_EXTCON_H__ */
    --
    1.7.4.1


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