drivers/usb/chipidea/otg.c

/*
 * otg.c - ChipIdea USB IP core OTG driver
 *
 * Copyright (C) 2013 Freescale Semiconductor, Inc.
 *
 * Author: Peter Chen
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/*
 * This file mainly handles otgsc register, it may include OTG operation
 * in the future.
 */

#include <linux/usb/otg.h>
#include <linux/usb/gadget.h>
#include <linux/usb/chipidea.h>

#include "ci.h"
#include "bits.h"
#include "otg.h"

/**
 * ci_otg_role - pick role based on ID pin state
 * @ci: the controller
 */
enum ci_role ci_otg_role(struct ci_hdrc *ci)
{
	u32 sts = hw_read(ci, OP_OTGSC, ~0);
	enum ci_role role = sts & OTGSC_ID
		? CI_ROLE_GADGET
		: CI_ROLE_HOST;

	return role;
}

/**
 * ci_role_work - perform role changing based on ID pin
 * @work: work struct
 */
static void ci_role_work(struct work_struct *work)
{
	struct ci_hdrc *ci = container_of(work, struct ci_hdrc, work);
	enum ci_role role = ci_otg_role(ci);

	if (role != ci->role) {
		dev_dbg(ci->dev, "switching from %s to %s\n",
			ci_role(ci)->name, ci->roles[role]->name);

		ci_role_stop(ci);
		ci_role_start(ci, role);
	}

	enable_irq(ci->irq);
}

/**
 * ci_hdrc_otg_init - initialize otg struct
 * ci: the controller
 */
int ci_hdrc_otg_init(struct ci_hdrc *ci)
{
	INIT_WORK(&ci->work, ci_role_work);
	ci->wq = create_singlethread_workqueue("ci_otg");
	if (!ci->wq) {
		dev_err(ci->dev, "can't create workqueue\n");
		return -ENODEV;
	}

	return 0;
}

/**
 * ci_hdrc_otg_destroy - destroy otg struct
 * ci: the controller
 */
void ci_hdrc_otg_destroy(struct ci_hdrc *ci)
{
	if (ci->wq) {
		flush_workqueue(ci->wq);
		destroy_workqueue(ci->wq);
	}
	ci_disable_otg_interrupt(ci, OTGSC_INT_EN_BITS);
	ci_clear_otg_interrupt(ci, OTGSC_INT_STATUS_BITS);
}