usb/mtu3/mtu3_dr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * mtu3_dr.c - dual role switch and host glue layer
 *
 * Copyright (C) 2016 MediaTek Inc.
 *
 * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
 */

#include <linux/usb/role.h>

#include "mtu3.h"
#include "mtu3_dr.h"
#include "mtu3_debug.h"

#define USB2_PORT 2
#define USB3_PORT 3

enum mtu3_vbus_id_state {
	MTU3_ID_FLOAT = 1,
	MTU3_ID_GROUND,
	MTU3_VBUS_OFF,
	MTU3_VBUS_VALID,
};

static char *mailbox_state_string(enum mtu3_vbus_id_state state)
{
	switch (state) {
	case MTU3_ID_FLOAT:
		return "ID_FLOAT";
	case MTU3_ID_GROUND:
		return "ID_GROUND";
	case MTU3_VBUS_OFF:
		return "VBUS_OFF";
	case MTU3_VBUS_VALID:
		return "VBUS_VALID";
	default:
		return "UNKNOWN";
	}
}

static void toggle_opstate(struct ssusb_mtk *ssusb)
{
	mtu3_setbits(ssusb->mac_base, U3D_DEVICE_CONTROL, DC_SESSION);
	mtu3_setbits(ssusb->mac_base, U3D_POWER_MANAGEMENT, SOFT_CONN);
}

/* only port0 supports dual-role mode */
static int ssusb_port0_switch(struct ssusb_mtk *ssusb,
	int version, bool tohost)
{
	void __iomem *ibase = ssusb->ippc_base;
	u32 value;

	dev_dbg(ssusb->dev, "%s (switch u%d port0 to %s)\n", __func__,
		version, tohost ? "host" : "device");

	if (version == USB2_PORT) {
		/* 1. power off and disable u2 port0 */
		value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
		value |= SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS;
		mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);

		/* 2. power on, enable u2 port0 and select its mode */
		value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
		value &= ~(SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS);
		value = tohost ? (value | SSUSB_U2_PORT_HOST_SEL) :
			(value & (~SSUSB_U2_PORT_HOST_SEL));
		mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);
	} else {
		/* 1. power off and disable u3 port0 */
		value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
		value |= SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS;
		mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);

		/* 2. power on, enable u3 port0 and select its mode */
		value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
		value &= ~(SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS);
		value = tohost ? (value | SSUSB_U3_PORT_HOST_SEL) :
			(value & (~SSUSB_U3_PORT_HOST_SEL));
		mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);
	}

	return 0;
}

static void switch_port_to_host(struct ssusb_mtk *ssusb)
{
	u32 check_clk = 0;

	dev_dbg(ssusb->dev, "%s\n", __func__);

	ssusb_port0_switch(ssusb, USB2_PORT, true);

	if (ssusb->otg_switch.is_u3_drd) {
		ssusb_port0_switch(ssusb, USB3_PORT, true);
		check_clk = SSUSB_U3_MAC_RST_B_STS;
	}

	ssusb_check_clocks(ssusb, check_clk);

	/* after all clocks are stable */
	toggle_opstate(ssusb);
}

static void switch_port_to_device(struct ssusb_mtk *ssusb)
{
	u32 check_clk = 0;

	dev_dbg(ssusb->dev, "%s\n", __func__);

	ssusb_port0_switch(ssusb, USB2_PORT, false);

	if (ssusb->otg_switch.is_u3_drd) {
		ssusb_port0_switch(ssusb, USB3_PORT, false);
		check_clk = SSUSB_U3_MAC_RST_B_STS;
	}

	ssusb_check_clocks(ssusb, check_clk);
}

int ssusb_set_vbus(struct otg_switch_mtk *otg_sx, int is_on)
{
	struct ssusb_mtk *ssusb =
		container_of(otg_sx, struct ssusb_mtk, otg_switch);
	struct regulator *vbus = otg_sx->vbus;
	int ret;

	/* vbus is optional */
	if (!vbus)
		return 0;

	dev_dbg(ssusb->dev, "%s: turn %s\n", __func__, is_on ? "on" : "off");

	if (is_on) {
		ret = regulator_enable(vbus);
		if (ret) {
			dev_err(ssusb->dev, "vbus regulator enable failed\n");
			return ret;
		}
	} else {
		regulator_disable(vbus);
	}

	return 0;
}

/*
 * switch to host: -> MTU3_VBUS_OFF --> MTU3_ID_GROUND
 * switch to device: -> MTU3_ID_FLOAT --> MTU3_VBUS_VALID
 */
static void ssusb_set_mailbox(struct otg_switch_mtk *otg_sx,
	enum mtu3_vbus_id_state status)
{
	struct ssusb_mtk *ssusb =
		container_of(otg_sx, struct ssusb_mtk, otg_switch);
	struct mtu3 *mtu = ssusb->u3d;

	dev_dbg(ssusb->dev, "mailbox %s\n", mailbox_state_string(status));
	mtu3_dbg_trace(ssusb->dev, "mailbox %s", mailbox_state_string(status));

	switch (status) {
	case MTU3_ID_GROUND:
		switch_port_to_host(ssusb);
		ssusb_set_vbus(otg_sx, 1);
		ssusb->is_host = true;
		break;
	case MTU3_ID_FLOAT:
		ssusb->is_host = false;
		ssusb_set_vbus(otg_sx, 0);
		switch_port_to_device(ssusb);
		break;
	case MTU3_VBUS_OFF:
		mtu3_stop(mtu);
		pm_relax(ssusb->dev);
		break;
	case MTU3_VBUS_VALID:
		/* avoid suspend when works as device */
		pm_stay_awake(ssusb->dev);
		mtu3_start(mtu);
		break;
	default:
		dev_err(ssusb->dev, "invalid state\n");
	}
}

static void ssusb_id_work(struct work_struct *work)
{
	struct otg_switch_mtk *otg_sx =
		container_of(work, struct otg_switch_mtk, id_work);

	if (otg_sx->id_event)
		ssusb_set_mailbox(otg_sx, MTU3_ID_GROUND);
	else
		ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);
}

static void ssusb_vbus_work(struct work_struct *work)
{
	struct otg_switch_mtk *otg_sx =
		container_of(work, struct otg_switch_mtk, vbus_work);

	if (otg_sx->vbus_event)
		ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);
	else
		ssusb_set_mailbox(otg_sx, MTU3_VBUS_OFF);
}

/*
 * @ssusb_id_notifier is called in atomic context, but @ssusb_set_mailbox
 * may sleep, so use work queue here
 */
static int ssusb_id_notifier(struct notifier_block *nb,
	unsigned long event, void *ptr)
{
	struct otg_switch_mtk *otg_sx =
		container_of(nb, struct otg_switch_mtk, id_nb);

	otg_sx->id_event = event;
	schedule_work(&otg_sx->id_work);

	return NOTIFY_DONE;
}

static int ssusb_vbus_notifier(struct notifier_block *nb,
	unsigned long event, void *ptr)
{
	struct otg_switch_mtk *otg_sx =
		container_of(nb, struct otg_switch_mtk, vbus_nb);

	otg_sx->vbus_event = event;
	schedule_work(&otg_sx->vbus_work);

	return NOTIFY_DONE;
}

static int ssusb_extcon_register(struct otg_switch_mtk *otg_sx)
{
	struct ssusb_mtk *ssusb =
		container_of(otg_sx, struct ssusb_mtk, otg_switch);
	struct extcon_dev *edev = otg_sx->edev;
	int ret;

	/* extcon is optional */
	if (!edev)
		return 0;

	otg_sx->vbus_nb.notifier_call = ssusb_vbus_notifier;
	ret = devm_extcon_register_notifier(ssusb->dev, edev, EXTCON_USB,
					&otg_sx->vbus_nb);
	if (ret < 0) {
		dev_err(ssusb->dev, "failed to register notifier for USB\n");
		return ret;
	}

	otg_sx->id_nb.notifier_call = ssusb_id_notifier;
	ret = devm_extcon_register_notifier(ssusb->dev, edev, EXTCON_USB_HOST,
					&otg_sx->id_nb);
	if (ret < 0) {
		dev_err(ssusb->dev, "failed to register notifier for USB-HOST\n");
		return ret;
	}

	dev_dbg(ssusb->dev, "EXTCON_USB: %d, EXTCON_USB_HOST: %d\n",
		extcon_get_state(edev, EXTCON_USB),
		extcon_get_state(edev, EXTCON_USB_HOST));

	/* default as host, switch to device mode if needed */
	if (extcon_get_state(edev, EXTCON_USB_HOST) == false)
		ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);
	if (extcon_get_state(edev, EXTCON_USB) == true)
		ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);

	return 0;
}

/*
 * We provide an interface via debugfs to switch between host and device modes
 * depending on user input.
 * This is useful in special cases, such as uses TYPE-A receptacle but also
 * wants to support dual-role mode.
 */
void ssusb_mode_switch(struct ssusb_mtk *ssusb, int to_host)
{
	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

	if (to_host) {
		ssusb_set_force_mode(ssusb, MTU3_DR_FORCE_HOST);
		ssusb_set_mailbox(otg_sx, MTU3_VBUS_OFF);
		ssusb_set_mailbox(otg_sx, MTU3_ID_GROUND);
	} else {
		ssusb_set_force_mode(ssusb, MTU3_DR_FORCE_DEVICE);
		ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);
		ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);
	}
}

void ssusb_set_force_mode(struct ssusb_mtk *ssusb,
			  enum mtu3_dr_force_mode mode)
{
	u32 value;

	value = mtu3_readl(ssusb->ippc_base, SSUSB_U2_CTRL(0));
	switch (mode) {
	case MTU3_DR_FORCE_DEVICE:
		value |= SSUSB_U2_PORT_FORCE_IDDIG | SSUSB_U2_PORT_RG_IDDIG;
		break;
	case MTU3_DR_FORCE_HOST:
		value |= SSUSB_U2_PORT_FORCE_IDDIG;
		value &= ~SSUSB_U2_PORT_RG_IDDIG;
		break;
	case MTU3_DR_FORCE_NONE:
		value &= ~(SSUSB_U2_PORT_FORCE_IDDIG | SSUSB_U2_PORT_RG_IDDIG);
		break;
	default:
		return;
	}
	mtu3_writel(ssusb->ippc_base, SSUSB_U2_CTRL(0), value);
}

static int ssusb_role_sw_set(struct usb_role_switch *sw, enum usb_role role)
{
	struct ssusb_mtk *ssusb = usb_role_switch_get_drvdata(sw);
	bool to_host = false;

	if (role == USB_ROLE_HOST)
		to_host = true;

	if (to_host ^ ssusb->is_host)
		ssusb_mode_switch(ssusb, to_host);

	return 0;
}

static enum usb_role ssusb_role_sw_get(struct usb_role_switch *sw)
{
	struct ssusb_mtk *ssusb = usb_role_switch_get_drvdata(sw);
	enum usb_role role;

	role = ssusb->is_host ? USB_ROLE_HOST : USB_ROLE_DEVICE;

	return role;
}

static int ssusb_role_sw_register(struct otg_switch_mtk *otg_sx)
{
	struct usb_role_switch_desc role_sx_desc = { 0 };
	struct ssusb_mtk *ssusb =
		container_of(otg_sx, struct ssusb_mtk, otg_switch);

	if (!otg_sx->role_sw_used)
		return 0;

	role_sx_desc.set = ssusb_role_sw_set;
	role_sx_desc.get = ssusb_role_sw_get;
	role_sx_desc.fwnode = dev_fwnode(ssusb->dev);
	role_sx_desc.driver_data = ssusb;
	otg_sx->role_sw = usb_role_switch_register(ssusb->dev, &role_sx_desc);

	return PTR_ERR_OR_ZERO(otg_sx->role_sw);
}

int ssusb_otg_switch_init(struct ssusb_mtk *ssusb)
{
	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
	int ret = 0;

	INIT_WORK(&otg_sx->id_work, ssusb_id_work);
	INIT_WORK(&otg_sx->vbus_work, ssusb_vbus_work);

	if (otg_sx->manual_drd_enabled)
		ssusb_dr_debugfs_init(ssusb);
	else if (otg_sx->role_sw_used)
		ret = ssusb_role_sw_register(otg_sx);
	else
		ret = ssusb_extcon_register(otg_sx);

	return ret;
}

void ssusb_otg_switch_exit(struct ssusb_mtk *ssusb)
{
	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;

	cancel_work_sync(&otg_sx->id_work);
	cancel_work_sync(&otg_sx->vbus_work);
	usb_role_switch_unregister(otg_sx->role_sw);
}