diff mbox

[01/19] usb: common: drd-lib: Add DRD lib for USB.

Message ID 1416921115-10467-2-git-send-email-george.cherian@ti.com (mailing list archive)
State New, archived
Headers show

Commit Message

George Cherian Nov. 25, 2014, 1:11 p.m. UTC 
Add USB DRD library. This Library facilitates to
switch roles between HOST and Device modes.

A DRD should be added to the library using usb_drd_add().
Register the HOST and UDC using usb_drd_register_hcd/udc().
Un-Register the HOST and UDC using usb_drd_unregister_hcd/udc().

Depending on the state of IP -
Call the following to start/stop HOST controller
usb_drd_start/stop_hcd().
This internally calls usb_add/remove_hcd() or IP specific low level start/stop
defined in ll_start/stop

Call the following to start/stop UDC
usb_drd_start/stop_udc().
This internally calls udc_start/udc_stop() or IP specific low level start/stop
defined in ll_start/stop

Signed-off-by: George Cherian <george.cherian@ti.com>
---
 drivers/usb/Kconfig          |  15 ++
 drivers/usb/common/Makefile  |   1 +
 drivers/usb/common/drd-lib.c | 346 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/usb/drd.h      |  77 ++++++++++
 4 files changed, 439 insertions(+)
 create mode 100644 drivers/usb/common/drd-lib.c
 create mode 100644 include/linux/usb/drd.h

Comments

Peter Chen Nov. 26, 2014, 5:14 a.m. UTC | #1 
On Tue, Nov 25, 2014 at 06:41:37PM +0530, George Cherian wrote:
> Add USB DRD library. This Library facilitates to
> switch roles between HOST and Device modes.
> 
> A DRD should be added to the library using usb_drd_add().
> Register the HOST and UDC using usb_drd_register_hcd/udc().
> Un-Register the HOST and UDC using usb_drd_unregister_hcd/udc().
> 
> Depending on the state of IP -
> Call the following to start/stop HOST controller
> usb_drd_start/stop_hcd().
> This internally calls usb_add/remove_hcd() or IP specific low level start/stop
> defined in ll_start/stop
> 
> Call the following to start/stop UDC
> usb_drd_start/stop_udc().
> This internally calls udc_start/udc_stop() or IP specific low level start/stop
> defined in ll_start/stop
> 
> Signed-off-by: George Cherian <george.cherian@ti.com>
> ---
>  drivers/usb/Kconfig          |  15 ++
>  drivers/usb/common/Makefile  |   1 +
>  drivers/usb/common/drd-lib.c | 346 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/usb/drd.h      |  77 ++++++++++
>  4 files changed, 439 insertions(+)
>  create mode 100644 drivers/usb/common/drd-lib.c
>  create mode 100644 include/linux/usb/drd.h
> 
> diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
> index ae481c3..ea0d944 100644
> --- a/drivers/usb/Kconfig
> +++ b/drivers/usb/Kconfig
> @@ -34,6 +34,21 @@ config USB_COMMON
>  	default y
>  	depends on USB || USB_GADGET
>  
> +config DRD_LIB
> +	tristate  "DRD Library support"
> +	default y
> +	depends on USB && USB_GADGET
> +	---help---
> +	  This option adds DRD Library support for Universal Serial Bus (USB).
> +	  DRD Library faciliatets the Role switching by HOST and DEVICE roles,
> +	  If your hardware has a Dual Role Device.
> +
> +	  The DRD Library uses USB core API's to start/stop HOST controllers,
> +	  UDC API's to start/stop DEVICE controllers, ther by enabling to
> +	  switch roles between HOST and Device modes.

%s/ther by/thereby

> +
> +	  Say N if unsure.
> +
>  config USB_ARCH_HAS_HCD
>  	def_bool y
>  
> diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
> index ca2f8bd..e2c1593 100644
> --- a/drivers/usb/common/Makefile
> +++ b/drivers/usb/common/Makefile
> @@ -7,3 +7,4 @@ usb-common-y			  += common.o
>  usb-common-$(CONFIG_USB_LED_TRIG) += led.o
>  
>  obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
> +obj-$(CONFIG_DRD_LIB)       += drd-lib.o
> diff --git a/drivers/usb/common/drd-lib.c b/drivers/usb/common/drd-lib.c
> new file mode 100644
> index 0000000..6159436
> --- /dev/null
> +++ b/drivers/usb/common/drd-lib.c
> @@ -0,0 +1,346 @@
> +/**
> + * drd-lib.c - USB DRD library functions
> + *
> + * Copyright (C) 2014 Texas Instruments
> + * Author: George Cherian <george.cherian@ti.com>
> + *
> + * This program is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2  of
> + * the License as published by the Free Software Foundation.
> + *
> + * 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/device.h>
> +#include <linux/err.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/usb.h>
> +
> +#include <linux/usb/hcd.h>
> +#include <linux/usb/gadget.h>
> +#include <linux/usb/drd.h>
> +
> +/**
> + * struct usb_drd - describes one dual role device
> + * @host - the HOST controller device of this drd
> + * @gadget - the gadget of drd
> + * @parent - the device to the actual controller
> + * @list - for use by the drd lib
> + * @state - specifies the current state
> + *
> + * This represents the internal data structure which is used by the UDC-class
> + * to hold information about udc driver and gadget together.
> + */

It is dual role struct, why you only talk about device?

> +struct usb_drd {
> +	struct usb_drd_host	*host;
> +	struct usb_drd_gadget	*gadget;
> +	struct device		*parent;
> +	struct list_head	list;
> +	unsigned int		state;
> +};
> +
> +static LIST_HEAD(drd_list);
> +static DEFINE_SPINLOCK(drd_lock);
> +
> +static struct usb_drd *usb_drd_get_dev(struct device *parent)
> +{
> +	struct usb_drd *drd;
> +
> +	spin_lock(&drd_lock);
> +	list_for_each_entry(drd, &drd_list, list)
> +		if (drd->parent == parent)
> +			goto out;
> +	drd = NULL;
> +out:
> +	spin_unlock(&drd_lock);
> +
> +	return drd;
> +}
> +
> +int usb_drd_get_state(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	return drd->state;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_get_state);
> +
> +int usb_drd_release(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +	int ret;
> +
> +	spin_lock(&drd_lock);
> +	list_for_each_entry(drd, &drd_list, list) {
> +		if (drd->parent == parent) {
> +			kfree(drd);
> +			ret = 0;
> +			goto out;
> +		}
> +	}
> +	ret = -ENODEV;
> +out:
> +	spin_unlock(&drd_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_release);
> +
> +int usb_drd_add(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = kzalloc(sizeof(*drd), GFP_KERNEL);
> +	if (!drd)
> +		return -ENOMEM;
> +
> +	spin_lock(&drd_lock);
> +	drd->parent = parent;
> +	list_add_tail(&drd->list, &drd_list);
> +	drd->state = DRD_UNREGISTERED;
> +
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_add);
> +
> +int usb_drd_register_hcd(struct device *parent, struct usb_drd_host *host)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	spin_lock(&drd_lock);
> +	drd->host = host;
> +	drd->state |= DRD_HOST_REGISTERED | DRD_HOST_ACTIVE;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_register_hcd);
> +
> +int usb_drd_unregister_hcd(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	spin_lock(&drd_lock);
> +	drd->state &= ~(DRD_HOST_REGISTERED | DRD_HOST_ACTIVE);
> +	spin_unlock(&drd_lock);
> +	kfree(drd->host);

It is better to allocate and free memory at the same file, either
both at DRD LIB APIs, or at host controller and udc driver.

> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_unregister_hcd);
> +
> +int usb_drd_start_hcd(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +	struct usb_drd_setup *setup;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	if (WARN_ON(!(drd->state & DRD_HOST_REGISTERED)))
> +		return -EINVAL;
> +
> +	setup = drd->host->host_setup;
> +	if (setup && setup->ll_start)
> +		setup->ll_start(setup->data);
> +
> +	usb_add_hcd(drd->host->main_hcd,
> +		    drd->host->hcd_irq, IRQF_SHARED);
> +	if (drd->host->shared_hcd)
> +		usb_add_hcd(drd->host->shared_hcd,
> +			    drd->host->hcd_irq, IRQF_SHARED);

Check return value please.

Peter
> +
> +	spin_lock(&drd_lock);
> +	drd->state |= DRD_HOST_ACTIVE;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_start_hcd);
> +
> +int usb_drd_stop_hcd(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +	struct usb_drd_setup *setup;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	if (WARN_ON(!(drd->state & DRD_HOST_ACTIVE)))
> +		return -EINVAL;
> +
> +	setup = drd->host->host_setup;
> +	if (setup && setup->ll_stop)
> +		setup->ll_stop(setup->data);
> +	if (drd->host->shared_hcd)
> +		usb_remove_hcd(drd->host->shared_hcd);
> +
> +	usb_remove_hcd(drd->host->main_hcd);
> +
> +	spin_lock(&drd_lock);
> +	drd->state = drd->state & ~DRD_HOST_ACTIVE;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_stop_hcd);
> +
> +int usb_drd_register_udc(struct device *parent, struct usb_drd_gadget *gadget)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	spin_lock(&drd_lock);
> +	drd->gadget = gadget;
> +	drd->state |= DRD_DEVICE_REGISTERED;
> +	if (drd->gadget->g_driver)
> +		drd->state |= DRD_DEVICE_ACTIVE;
> +
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_register_udc);
> +
> +int usb_drd_register_udc_driver(struct device *parent,
> +				struct usb_gadget_driver *driver)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	spin_lock(&drd_lock);
> +	drd->gadget->g_driver = driver;
> +	drd->state |= DRD_DEVICE_ACTIVE;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_register_udc_driver);
> +
> +int usb_drd_unregister_udc(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	spin_lock(&drd_lock);
> +	drd->state &= ~(DRD_DEVICE_REGISTERED | DRD_DEVICE_ACTIVE);
> +	spin_unlock(&drd_lock);
> +	kfree(drd->gadget->gadget_setup);
> +	kfree(drd->gadget);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_unregister_udc);
> +
> +int usb_drd_unregister_udc_driver(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +	struct usb_drd_gadget *drd_gadget;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +	drd_gadget = drd->gadget;
> +
> +	spin_lock(&drd_lock);
> +	drd->state &= ~DRD_DEVICE_ACTIVE;
> +	drd_gadget->g_driver = NULL;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_unregister_udc_driver);
> +
> +int usb_drd_start_udc(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +	struct usb_drd_gadget *drd_gadget;
> +	struct usb_drd_setup *setup;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	if (WARN_ON(!(drd->state & DRD_DEVICE_REGISTERED)))
> +		return -EINVAL;
> +
> +	drd_gadget = drd->gadget;
> +	setup = drd_gadget->gadget_setup;
> +
> +	if (setup && setup->ll_start)
> +		setup->ll_start(setup->data);
> +
> +	usb_add_gadget_udc_release(parent, drd_gadget->gadget,
> +				   setup->ll_release);
> +	spin_lock(&drd_lock);
> +	drd->state |= DRD_DEVICE_ACTIVE;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_start_udc);
> +
> +int usb_drd_stop_udc(struct device *parent)
> +{
> +	struct usb_drd	*drd;
> +	struct usb_drd_gadget *drd_gadget;
> +	struct usb_drd_setup *setup;
> +
> +	drd = usb_drd_get_dev(parent);
> +	if (!drd)
> +		return -ENODEV;
> +
> +	if (WARN_ON(!(drd->state & DRD_DEVICE_REGISTERED)))
> +		return -EINVAL;
> +
> +	drd_gadget = drd->gadget;
> +	setup = drd_gadget->gadget_setup;
> +	if (setup && setup->ll_stop)
> +		setup->ll_stop(setup->data);
> +
> +	usb_del_gadget_udc(drd_gadget->gadget);
> +
> +	spin_lock(&drd_lock);
> +	drd->state = drd->state & ~DRD_DEVICE_ACTIVE;
> +	spin_unlock(&drd_lock);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(usb_drd_stop_udc);
> +
> +MODULE_DESCRIPTION("USB-DRD Library");
> +MODULE_AUTHOR("George Cherian <george.cherian@ti.com>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/usb/drd.h b/include/linux/usb/drd.h
> new file mode 100644
> index 0000000..71c64dc
> --- /dev/null
> +++ b/include/linux/usb/drd.h
> @@ -0,0 +1,77 @@
> +#include <linux/usb/gadget.h>
> +#include <linux/usb/otg.h>
> +#include <linux/usb/hcd.h>
> +
> +struct usb_drd_setup {
> +	int	(*ll_start)(void *);
> +	int	(*ll_stop)(void *);
> +	void	(*ll_release)(struct device *);
> +	void	*data;
> +};
> +
> +struct usb_drd_host {
> +	struct usb_hcd		*main_hcd;
> +	struct usb_hcd		*shared_hcd;
> +	int			hcd_irq;
> +	struct usb_drd_setup *host_setup;
> +};
> +
> +struct usb_drd_gadget {
> +	struct usb_gadget_driver *g_driver;
> +	struct usb_gadget *gadget;
> +	struct usb_drd_setup *gadget_setup;
> +};
> +
> +#define DRD_UNREGISTERED	0x0
> +#define DRD_DEVICE_REGISTERED	0x1
> +#define DRD_HOST_REGISTERED	0x2
> +#define DRD_HOST_ACTIVE		0x4
> +#define DRD_DEVICE_ACTIVE	0x8
> +
> +#if IS_ENABLED(CONFIG_DRD_LIB)
> +int usb_drd_release(struct device *parent);
> +int usb_drd_add(struct device *parent);
> +int usb_drd_register_udc(struct device *parent,
> +			 struct usb_drd_gadget *gadget);
> +int usb_drd_register_udc_driver(struct device *parent,
> +				struct usb_gadget_driver *driver);
> +int usb_drd_unregister_udc(struct device *parent);
> +int usb_drd_unregister_udc_driver(struct device *parent);
> +int usb_drd_register_hcd(struct device *parent,
> +			 struct usb_drd_host *host);
> +int usb_drd_unregister_hcd(struct device *parent);
> +int usb_drd_start_hcd(struct device *parent);
> +int usb_drd_stop_hcd(struct device *parent);
> +int usb_drd_start_udc(struct device *parent);
> +int usb_drd_stop_udc(struct device *parent);
> +int usb_drd_get_state(struct device *parent);
> +#else
> +static inline int usb_drd_release(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_add(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_register_udc(struct device *parent,
> +				       struct usb_drd_gadget *gadget)
> +{ return 0; }
> +static inline int usb_drd_register_udc_driver(struct device *parent,
> +					      struct usb_gadget_driver *driver)
> +{ return 0; }
> +static inline int usb_drd_unregister_udc(struct device *parent,
> +					 struct usb_drd_gadget *gadget)
> +{ return 0; }
> +static inline int usb_drd_unregister_udc_driver(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_register_hcd(struct device *parent,
> +				       struct usb_drd_host *host)
> +{ return 0; }
> +static inline int usb_drd_unregister_hcd(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_stop_hcd(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_start_udc(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_stop_udc(struct device *parent)
> +{ return 0; }
> +static inline int usb_drd_get_state(struct device *parent)
> +{ return 0; }
> +#endif
> -- 
> 1.8.3.1
>
diff mbox

Patch

diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index ae481c3..ea0d944 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -34,6 +34,21 @@  config USB_COMMON
 	default y
 	depends on USB || USB_GADGET
 
+config DRD_LIB
+	tristate  "DRD Library support"
+	default y
+	depends on USB && USB_GADGET
+	---help---
+	  This option adds DRD Library support for Universal Serial Bus (USB).
+	  DRD Library faciliatets the Role switching by HOST and DEVICE roles,
+	  If your hardware has a Dual Role Device.
+
+	  The DRD Library uses USB core API's to start/stop HOST controllers,
+	  UDC API's to start/stop DEVICE controllers, ther by enabling to
+	  switch roles between HOST and Device modes.
+
+	  Say N if unsure.
+
 config USB_ARCH_HAS_HCD
 	def_bool y
 
diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
index ca2f8bd..e2c1593 100644
--- a/drivers/usb/common/Makefile
+++ b/drivers/usb/common/Makefile
@@ -7,3 +7,4 @@  usb-common-y			  += common.o
 usb-common-$(CONFIG_USB_LED_TRIG) += led.o
 
 obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
+obj-$(CONFIG_DRD_LIB)       += drd-lib.o
diff --git a/drivers/usb/common/drd-lib.c b/drivers/usb/common/drd-lib.c
new file mode 100644
index 0000000..6159436
--- /dev/null
+++ b/drivers/usb/common/drd-lib.c
@@ -0,0 +1,346 @@ 
+/**
+ * drd-lib.c - USB DRD library functions
+ *
+ * Copyright (C) 2014 Texas Instruments
+ * Author: George Cherian <george.cherian@ti.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * 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/device.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include <linux/usb/hcd.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/drd.h>
+
+/**
+ * struct usb_drd - describes one dual role device
+ * @host - the HOST controller device of this drd
+ * @gadget - the gadget of drd
+ * @parent - the device to the actual controller
+ * @list - for use by the drd lib
+ * @state - specifies the current state
+ *
+ * This represents the internal data structure which is used by the UDC-class
+ * to hold information about udc driver and gadget together.
+ */
+struct usb_drd {
+	struct usb_drd_host	*host;
+	struct usb_drd_gadget	*gadget;
+	struct device		*parent;
+	struct list_head	list;
+	unsigned int		state;
+};
+
+static LIST_HEAD(drd_list);
+static DEFINE_SPINLOCK(drd_lock);
+
+static struct usb_drd *usb_drd_get_dev(struct device *parent)
+{
+	struct usb_drd *drd;
+
+	spin_lock(&drd_lock);
+	list_for_each_entry(drd, &drd_list, list)
+		if (drd->parent == parent)
+			goto out;
+	drd = NULL;
+out:
+	spin_unlock(&drd_lock);
+
+	return drd;
+}
+
+int usb_drd_get_state(struct device *parent)
+{
+	struct usb_drd	*drd;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	return drd->state;
+}
+EXPORT_SYMBOL_GPL(usb_drd_get_state);
+
+int usb_drd_release(struct device *parent)
+{
+	struct usb_drd	*drd;
+	int ret;
+
+	spin_lock(&drd_lock);
+	list_for_each_entry(drd, &drd_list, list) {
+		if (drd->parent == parent) {
+			kfree(drd);
+			ret = 0;
+			goto out;
+		}
+	}
+	ret = -ENODEV;
+out:
+	spin_unlock(&drd_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(usb_drd_release);
+
+int usb_drd_add(struct device *parent)
+{
+	struct usb_drd	*drd;
+
+	drd = kzalloc(sizeof(*drd), GFP_KERNEL);
+	if (!drd)
+		return -ENOMEM;
+
+	spin_lock(&drd_lock);
+	drd->parent = parent;
+	list_add_tail(&drd->list, &drd_list);
+	drd->state = DRD_UNREGISTERED;
+
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_add);
+
+int usb_drd_register_hcd(struct device *parent, struct usb_drd_host *host)
+{
+	struct usb_drd	*drd;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	spin_lock(&drd_lock);
+	drd->host = host;
+	drd->state |= DRD_HOST_REGISTERED | DRD_HOST_ACTIVE;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_register_hcd);
+
+int usb_drd_unregister_hcd(struct device *parent)
+{
+	struct usb_drd	*drd;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	spin_lock(&drd_lock);
+	drd->state &= ~(DRD_HOST_REGISTERED | DRD_HOST_ACTIVE);
+	spin_unlock(&drd_lock);
+	kfree(drd->host);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_unregister_hcd);
+
+int usb_drd_start_hcd(struct device *parent)
+{
+	struct usb_drd	*drd;
+	struct usb_drd_setup *setup;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	if (WARN_ON(!(drd->state & DRD_HOST_REGISTERED)))
+		return -EINVAL;
+
+	setup = drd->host->host_setup;
+	if (setup && setup->ll_start)
+		setup->ll_start(setup->data);
+
+	usb_add_hcd(drd->host->main_hcd,
+		    drd->host->hcd_irq, IRQF_SHARED);
+	if (drd->host->shared_hcd)
+		usb_add_hcd(drd->host->shared_hcd,
+			    drd->host->hcd_irq, IRQF_SHARED);
+
+	spin_lock(&drd_lock);
+	drd->state |= DRD_HOST_ACTIVE;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_start_hcd);
+
+int usb_drd_stop_hcd(struct device *parent)
+{
+	struct usb_drd	*drd;
+	struct usb_drd_setup *setup;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	if (WARN_ON(!(drd->state & DRD_HOST_ACTIVE)))
+		return -EINVAL;
+
+	setup = drd->host->host_setup;
+	if (setup && setup->ll_stop)
+		setup->ll_stop(setup->data);
+	if (drd->host->shared_hcd)
+		usb_remove_hcd(drd->host->shared_hcd);
+
+	usb_remove_hcd(drd->host->main_hcd);
+
+	spin_lock(&drd_lock);
+	drd->state = drd->state & ~DRD_HOST_ACTIVE;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_stop_hcd);
+
+int usb_drd_register_udc(struct device *parent, struct usb_drd_gadget *gadget)
+{
+	struct usb_drd	*drd;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	spin_lock(&drd_lock);
+	drd->gadget = gadget;
+	drd->state |= DRD_DEVICE_REGISTERED;
+	if (drd->gadget->g_driver)
+		drd->state |= DRD_DEVICE_ACTIVE;
+
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_register_udc);
+
+int usb_drd_register_udc_driver(struct device *parent,
+				struct usb_gadget_driver *driver)
+{
+	struct usb_drd	*drd;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	spin_lock(&drd_lock);
+	drd->gadget->g_driver = driver;
+	drd->state |= DRD_DEVICE_ACTIVE;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_register_udc_driver);
+
+int usb_drd_unregister_udc(struct device *parent)
+{
+	struct usb_drd	*drd;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	spin_lock(&drd_lock);
+	drd->state &= ~(DRD_DEVICE_REGISTERED | DRD_DEVICE_ACTIVE);
+	spin_unlock(&drd_lock);
+	kfree(drd->gadget->gadget_setup);
+	kfree(drd->gadget);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_unregister_udc);
+
+int usb_drd_unregister_udc_driver(struct device *parent)
+{
+	struct usb_drd	*drd;
+	struct usb_drd_gadget *drd_gadget;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+	drd_gadget = drd->gadget;
+
+	spin_lock(&drd_lock);
+	drd->state &= ~DRD_DEVICE_ACTIVE;
+	drd_gadget->g_driver = NULL;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_unregister_udc_driver);
+
+int usb_drd_start_udc(struct device *parent)
+{
+	struct usb_drd	*drd;
+	struct usb_drd_gadget *drd_gadget;
+	struct usb_drd_setup *setup;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	if (WARN_ON(!(drd->state & DRD_DEVICE_REGISTERED)))
+		return -EINVAL;
+
+	drd_gadget = drd->gadget;
+	setup = drd_gadget->gadget_setup;
+
+	if (setup && setup->ll_start)
+		setup->ll_start(setup->data);
+
+	usb_add_gadget_udc_release(parent, drd_gadget->gadget,
+				   setup->ll_release);
+	spin_lock(&drd_lock);
+	drd->state |= DRD_DEVICE_ACTIVE;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_start_udc);
+
+int usb_drd_stop_udc(struct device *parent)
+{
+	struct usb_drd	*drd;
+	struct usb_drd_gadget *drd_gadget;
+	struct usb_drd_setup *setup;
+
+	drd = usb_drd_get_dev(parent);
+	if (!drd)
+		return -ENODEV;
+
+	if (WARN_ON(!(drd->state & DRD_DEVICE_REGISTERED)))
+		return -EINVAL;
+
+	drd_gadget = drd->gadget;
+	setup = drd_gadget->gadget_setup;
+	if (setup && setup->ll_stop)
+		setup->ll_stop(setup->data);
+
+	usb_del_gadget_udc(drd_gadget->gadget);
+
+	spin_lock(&drd_lock);
+	drd->state = drd->state & ~DRD_DEVICE_ACTIVE;
+	spin_unlock(&drd_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_drd_stop_udc);
+
+MODULE_DESCRIPTION("USB-DRD Library");
+MODULE_AUTHOR("George Cherian <george.cherian@ti.com>");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/usb/drd.h b/include/linux/usb/drd.h
new file mode 100644
index 0000000..71c64dc
--- /dev/null
+++ b/include/linux/usb/drd.h
@@ -0,0 +1,77 @@ 
+#include <linux/usb/gadget.h>
+#include <linux/usb/otg.h>
+#include <linux/usb/hcd.h>
+
+struct usb_drd_setup {
+	int	(*ll_start)(void *);
+	int	(*ll_stop)(void *);
+	void	(*ll_release)(struct device *);
+	void	*data;
+};
+
+struct usb_drd_host {
+	struct usb_hcd		*main_hcd;
+	struct usb_hcd		*shared_hcd;
+	int			hcd_irq;
+	struct usb_drd_setup *host_setup;
+};
+
+struct usb_drd_gadget {
+	struct usb_gadget_driver *g_driver;
+	struct usb_gadget *gadget;
+	struct usb_drd_setup *gadget_setup;
+};
+
+#define DRD_UNREGISTERED	0x0
+#define DRD_DEVICE_REGISTERED	0x1
+#define DRD_HOST_REGISTERED	0x2
+#define DRD_HOST_ACTIVE		0x4
+#define DRD_DEVICE_ACTIVE	0x8
+
+#if IS_ENABLED(CONFIG_DRD_LIB)
+int usb_drd_release(struct device *parent);
+int usb_drd_add(struct device *parent);
+int usb_drd_register_udc(struct device *parent,
+			 struct usb_drd_gadget *gadget);
+int usb_drd_register_udc_driver(struct device *parent,
+				struct usb_gadget_driver *driver);
+int usb_drd_unregister_udc(struct device *parent);
+int usb_drd_unregister_udc_driver(struct device *parent);
+int usb_drd_register_hcd(struct device *parent,
+			 struct usb_drd_host *host);
+int usb_drd_unregister_hcd(struct device *parent);
+int usb_drd_start_hcd(struct device *parent);
+int usb_drd_stop_hcd(struct device *parent);
+int usb_drd_start_udc(struct device *parent);
+int usb_drd_stop_udc(struct device *parent);
+int usb_drd_get_state(struct device *parent);
+#else
+static inline int usb_drd_release(struct device *parent)
+{ return 0; }
+static inline int usb_drd_add(struct device *parent)
+{ return 0; }
+static inline int usb_drd_register_udc(struct device *parent,
+				       struct usb_drd_gadget *gadget)
+{ return 0; }
+static inline int usb_drd_register_udc_driver(struct device *parent,
+					      struct usb_gadget_driver *driver)
+{ return 0; }
+static inline int usb_drd_unregister_udc(struct device *parent,
+					 struct usb_drd_gadget *gadget)
+{ return 0; }
+static inline int usb_drd_unregister_udc_driver(struct device *parent)
+{ return 0; }
+static inline int usb_drd_register_hcd(struct device *parent,
+				       struct usb_drd_host *host)
+{ return 0; }
+static inline int usb_drd_unregister_hcd(struct device *parent)
+{ return 0; }
+static inline int usb_drd_stop_hcd(struct device *parent)
+{ return 0; }
+static inline int usb_drd_start_udc(struct device *parent)
+{ return 0; }
+static inline int usb_drd_stop_udc(struct device *parent)
+{ return 0; }
+static inline int usb_drd_get_state(struct device *parent)
+{ return 0; }
+#endif