diff options
Diffstat (limited to 'drivers/usb/otg/otg_id.c')
| -rw-r--r-- | drivers/usb/otg/otg_id.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/drivers/usb/otg/otg_id.c b/drivers/usb/otg/otg_id.c new file mode 100644 index 0000000..8037edb --- /dev/null +++ b/drivers/usb/otg/otg_id.c @@ -0,0 +1,205 @@ +/* + * Copyright (C) 2011 Google, Inc. + * + * Author: + * Colin Cross <ccross@android.com> + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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. + * + */ + +#include <linux/kernel.h> +#include <linux/mutex.h> +#include <linux/notifier.h> +#include <linux/usb/otg_id.h> + +static DEFINE_MUTEX(otg_id_lock); +static struct plist_head otg_id_plist = + PLIST_HEAD_INIT(otg_id_plist); +static struct otg_id_notifier_block *otg_id_active; +static bool otg_id_cancelling; +static bool otg_id_inited; +static int otg_id_suspended; +static bool otg_id_pending; + +static void otg_id_cancel(void) +{ + if (otg_id_active) { + otg_id_cancelling = true; + mutex_unlock(&otg_id_lock); + + otg_id_active->cancel(otg_id_active); + + mutex_lock(&otg_id_lock); + otg_id_cancelling = false; + } +} + +static void __otg_id_notify(void) +{ + int ret; + struct otg_id_notifier_block *otg_id_nb; + bool proxy_wait = false; + if (plist_head_empty(&otg_id_plist)) + return; + + plist_for_each_entry(otg_id_nb, &otg_id_plist, p) { + if (proxy_wait) { + if (otg_id_nb->proxy_wait) + ret = otg_id_nb->proxy_wait(otg_id_nb); + } else { + ret = otg_id_nb->detect(otg_id_nb); + } + if (ret == OTG_ID_HANDLED) { + otg_id_active = otg_id_nb; + return; + } + if (ret == OTG_ID_PROXY_WAIT) + proxy_wait = true; + + } + + WARN(1, "otg id event not handled"); + otg_id_active = NULL; +} + +int otg_id_init(void) +{ + mutex_lock(&otg_id_lock); + + otg_id_inited = true; + __otg_id_notify(); + + mutex_unlock(&otg_id_lock); + return 0; +} +late_initcall(otg_id_init); + +/** + * otg_id_register_notifier + * @otg_id_nb: notifier block containing priority and callback function + * + * Register a notifier that will be called on any USB cable state change. + * The priority determines the order the callback will be called in, a higher + * number will be called first. A callback function needs to determine the + * type of USB cable that is connected. If it can determine the type, it + * should notify the appropriate drivers (for example, call an otg notifier + * with USB_EVENT_VBUS), and return OTG_ID_HANDLED. Once a callback has + * returned OTG_ID_HANDLED, it is responsible for calling otg_id_notify() when + * the detected USB cable is disconnected. + */ +int otg_id_register_notifier(struct otg_id_notifier_block *otg_id_nb) +{ + plist_node_init(&otg_id_nb->p, otg_id_nb->priority); + + mutex_lock(&otg_id_lock); + plist_add(&otg_id_nb->p, &otg_id_plist); + + if (otg_id_inited) { + otg_id_cancel(); + __otg_id_notify(); + } + + mutex_unlock(&otg_id_lock); + + return 0; +} + +void otg_id_unregister_notifier(struct otg_id_notifier_block *otg_id_nb) +{ + mutex_lock(&otg_id_lock); + + plist_del(&otg_id_nb->p, &otg_id_plist); + + if (otg_id_inited && (otg_id_active == otg_id_nb)) { + otg_id_cancel(); + __otg_id_notify(); + } + + mutex_unlock(&otg_id_lock); +} + +/** + * otg_id_notify + * + * Notify listeners on any USB cable state change. + * + * A driver may only call otg_id_notify if it returned OTG_ID_HANDLED the last + * time it's notifier was called, and it's cancel function has not been called. + */ +void otg_id_notify(void) +{ + mutex_lock(&otg_id_lock); + + if (otg_id_cancelling) + goto out; + + if (otg_id_suspended != 0) { + otg_id_pending = true; + goto out; + } + + __otg_id_notify(); +out: + mutex_unlock(&otg_id_lock); +} + +/** + * otg_id_suspend + * + * Mark the otg_id subsystem as going into suspend. From here on out, + * any notifications will be deferred until the last otg_id client resumes. + * If there is a pending notification when calling this function, it will + * return a negative errno and expects that the caller will abort suspend. + * Returs 0 on success. + */ +int otg_id_suspend(void) +{ + int ret = 0; + + mutex_lock(&otg_id_lock); + + /* + * if there's a pending notification, tell the caller to abort suspend + */ + if (otg_id_suspended != 0 && otg_id_pending) { + pr_info("otg_id: pending notification, should abort suspend\n"); + ret = -EBUSY; + goto out; + } + + otg_id_suspended++; +out: + mutex_unlock(&otg_id_lock); + return ret; +} + +/** + * otg_id_resume + * + * Inform the otg_id subsystem that a client is resuming. If this is the + * last client to be resumed and there's a pending notification, + * otg_id_notify() is called. + */ +void otg_id_resume(void) +{ + mutex_lock(&otg_id_lock); + if (WARN(!otg_id_suspended, "unbalanced otg_id_resume\n")) + goto out; + if (--otg_id_suspended == 0) { + if (otg_id_pending) { + pr_info("otg_id: had pending notification\n"); + otg_id_pending = false; + __otg_id_notify(); + } + } +out: + mutex_unlock(&otg_id_lock); +} |