drivers/usb/dwc3/dwc3-apple.c - linux/kernel/git/gregkh/tty - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Apple Silicon DWC3 Glue driver
  * Copyright (C) The Asahi Linux Contributors
  *
  * Based on:
  *  - dwc3-qcom.c Copyright (c) 2018, The Linux Foundation. All rights reserved.
  *  - dwc3-of-simple.c Copyright (c) 2015 Texas Instruments Incorporated - https://www.ti.com
  */

 #include <linux/of.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>

 #include "glue.h"

 /*
  * This platform requires a very specific sequence of operations to bring up dwc3 and its USB3 PHY:
  *
  * 1) The PHY itself has to be brought up; for this we need to know the mode (USB3,
  *    USB3+DisplayPort, USB4, etc) and the lane orientation. This happens through typec_mux_set.
  * 2) DWC3 has to be brought up but we must not touch the gadget area or start xhci yet.
  * 3) The PHY bring-up has to be finalized and dwc3's PIPE interface has to be switched to the
  *    USB3 PHY, this is done inside phy_set_mode.
  * 4) We can now initialize xhci or gadget mode.
  *
  * We can switch 1 and 2 but 3 has to happen after (1 and 2) and 4 has to happen after 3.
  *
  * And then to bring this all down again:
  *
  * 1) DWC3 has to exit host or gadget mode and must no longer touch those registers
  * 2) The PHY has to switch dwc3's PIPE interface back to the dummy backend
  * 3) The PHY itself can be shut down, this happens from typec_mux_set
  *
  * We also can't transition the PHY from one mode to another while dwc3 is up and running (this is
  * slightly wrong, some transitions are possible, others aren't but because we have no documentation
  * for this I'd rather play it safe).
  *
  * After both the PHY and dwc3 are initialized we will only ever see a single "new device connected"
  * event. If we just keep them running only the first device plugged in will ever work. XHCI's port
  * status register actually does show the correct state but no interrupt ever comes in. In gadget
  * mode we don't even get a USBDisconnected event and everything looks like there's still something
  * connected on the other end.
  * This can be partially explained because the USB2 D+/D- lines are connected through a stateful
  * eUSB2 repeater which in turn is controlled by a variant of the TI TPS6598x USB PD chip which
  * resets the repeater out-of-band everytime the CC lines are (dis)connected. This then requires a
  * PHY reset to make sure the PHY and the eUSB2 repeater state are synchronized again.
  *
  * And to make this all extra fun: If we get the order of some of this wrong either the port is just
  * broken until a phy+dwc3 reset, or it's broken until a full SoC reset (likely because we can't
  * reset some parts of the PHY), or some watchdog kicks in after a few seconds and forces a full SoC
  * reset (mostly seen this with USB4/Thunderbolt but there's clearly some watchdog that hates
  * invalid states).
  *
  * Hence there's really no good way to keep dwc3 fully up and running after we disconnect a cable
  * because then we can't shut down the PHY anymore. And if we kept the PHY running in whatever mode
  * it was until the next cable is connected we'd need to tear it all down and bring it back up again
  * anyway to detect and use the next device.
  *
  * Instead, we just shut down everything when a cable is disconnected and transition to
  * DWC3_APPLE_NO_CABLE.
  * During initial probe we don't have any information about the connected cable and can't bring up
  * the PHY properly and thus also can't fully bring up dwc3. Instead, we just keep everything off
  * and defer the first dwc3 probe until we get the first cable connected event. Until then we stay
  * in DWC3_APPLE_PROBE_PENDING.
  * Once a cable is connected we then keep track of the controller mode here by transitioning to
  * DWC3_APPLE_HOST or DWC3_APPLE_DEVICE.
  */
 enum dwc3_apple_state {
 	DWC3_APPLE_PROBE_PENDING, /* Before first cable connection, dwc3_core_probe not called */
 	DWC3_APPLE_NO_CABLE, /* No cable connected, dwc3 suspended after dwc3_core_exit */
 	DWC3_APPLE_HOST, /* Cable connected, dwc3 in host mode */
 	DWC3_APPLE_DEVICE, /* Cable connected, dwc3 in device mode */
 };

 /**
  * struct dwc3_apple - Apple-specific DWC3 USB controller
  * @dwc: Core DWC3 structure
  * @dev: Pointer to the device structure
  * @mmio_resource: Resource to be passed to dwc3_core_probe
  * @apple_regs: Apple-specific DWC3 registers
  * @reset: Reset control
  * @role_sw: USB role switch
  * @lock: Mutex for synchronizing access
  * @state: Current state of the controller, see documentation for the enum for details
  */
 struct dwc3_apple {
 	struct dwc3 dwc;

 	struct device *dev;
 	struct resource *mmio_resource;
 	void __iomem *apple_regs;

 	struct reset_control *reset;
 	struct usb_role_switch *role_sw;

 	struct mutex lock;

 	enum dwc3_apple_state state;
 };

 #define to_dwc3_apple(d) container_of((d), struct dwc3_apple, dwc)

 /*
  * Apple Silicon dwc3 vendor-specific registers
  *
  * These registers were identified by tracing XNU's memory access patterns and correlating them with
  * debug output over serial to determine their names. We don't exactly know what these do but
  * without these USB3 devices sometimes don't work.
  */
 #define APPLE_DWC3_REGS_START 0xcd00
 #define APPLE_DWC3_REGS_END 0xcdff

 #define APPLE_DWC3_CIO_LFPS_OFFSET 0xcd38
 #define APPLE_DWC3_CIO_LFPS_OFFSET_VALUE 0xf800f80

 #define APPLE_DWC3_CIO_BW_NGT_OFFSET 0xcd3c
 #define APPLE_DWC3_CIO_BW_NGT_OFFSET_VALUE 0xfc00fc0

 #define APPLE_DWC3_CIO_LINK_TIMER 0xcd40
 #define APPLE_DWC3_CIO_PENDING_HP_TIMER GENMASK(23, 16)
 #define APPLE_DWC3_CIO_PENDING_HP_TIMER_VALUE 0x14
 #define APPLE_DWC3_CIO_PM_LC_TIMER GENMASK(15, 8)
 #define APPLE_DWC3_CIO_PM_LC_TIMER_VALUE 0xa
 #define APPLE_DWC3_CIO_PM_ENTRY_TIMER GENMASK(7, 0)
 #define APPLE_DWC3_CIO_PM_ENTRY_TIMER_VALUE 0x10

 static inline void dwc3_apple_writel(struct dwc3_apple *appledwc, u32 offset, u32 value)
 {
 	writel(value, appledwc->apple_regs + offset - APPLE_DWC3_REGS_START);
 }

 static inline u32 dwc3_apple_readl(struct dwc3_apple *appledwc, u32 offset)
 {
 	return readl(appledwc->apple_regs + offset - APPLE_DWC3_REGS_START);
 }

 static inline void dwc3_apple_mask(struct dwc3_apple *appledwc, u32 offset, u32 mask, u32 value)
 {
 	u32 reg;

 	reg = dwc3_apple_readl(appledwc, offset);
 	reg &= ~mask;
 	reg |= value;
 	dwc3_apple_writel(appledwc, offset, reg);
 }

 static void dwc3_apple_setup_cio(struct dwc3_apple *appledwc)
 {
 	dwc3_apple_writel(appledwc, APPLE_DWC3_CIO_LFPS_OFFSET, APPLE_DWC3_CIO_LFPS_OFFSET_VALUE);
 	dwc3_apple_writel(appledwc, APPLE_DWC3_CIO_BW_NGT_OFFSET,
 			  APPLE_DWC3_CIO_BW_NGT_OFFSET_VALUE);
 	dwc3_apple_mask(appledwc, APPLE_DWC3_CIO_LINK_TIMER, APPLE_DWC3_CIO_PENDING_HP_TIMER,
 			FIELD_PREP(APPLE_DWC3_CIO_PENDING_HP_TIMER,
 				   APPLE_DWC3_CIO_PENDING_HP_TIMER_VALUE));
 	dwc3_apple_mask(appledwc, APPLE_DWC3_CIO_LINK_TIMER, APPLE_DWC3_CIO_PM_LC_TIMER,
 			FIELD_PREP(APPLE_DWC3_CIO_PM_LC_TIMER, APPLE_DWC3_CIO_PM_LC_TIMER_VALUE));
 	dwc3_apple_mask(appledwc, APPLE_DWC3_CIO_LINK_TIMER, APPLE_DWC3_CIO_PM_ENTRY_TIMER,
 			FIELD_PREP(APPLE_DWC3_CIO_PM_ENTRY_TIMER,
 				   APPLE_DWC3_CIO_PM_ENTRY_TIMER_VALUE));
 }

 static void dwc3_apple_set_ptrcap(struct dwc3_apple *appledwc, u32 mode)
 {
 	guard(spinlock_irqsave)(&appledwc->dwc.lock);
 	dwc3_set_prtcap(&appledwc->dwc, mode, false);
 }

 static int dwc3_apple_core_probe(struct dwc3_apple *appledwc)
 {
 	struct dwc3_probe_data probe_data = {};
 	int ret;

 	lockdep_assert_held(&appledwc->lock);
 	WARN_ON_ONCE(appledwc->state != DWC3_APPLE_PROBE_PENDING);

 	appledwc->dwc.dev = appledwc->dev;
 	probe_data.dwc = &appledwc->dwc;
 	probe_data.res = appledwc->mmio_resource;
 	probe_data.ignore_clocks_and_resets = true;
 	probe_data.skip_core_init_mode = true;
 	probe_data.properties = DWC3_DEFAULT_PROPERTIES;

 	ret = dwc3_core_probe(&probe_data);
 	if (ret)
 		return ret;

 	appledwc->state = DWC3_APPLE_NO_CABLE;
 	return 0;
 }

 static int dwc3_apple_core_init(struct dwc3_apple *appledwc)
 {
 	int ret;

 	lockdep_assert_held(&appledwc->lock);

 	switch (appledwc->state) {
 	case DWC3_APPLE_PROBE_PENDING:
 		ret = dwc3_apple_core_probe(appledwc);
 		if (ret)
 			dev_err(appledwc->dev, "Failed to probe DWC3 Core, err=%d\n", ret);
 		break;
 	case DWC3_APPLE_NO_CABLE:
 		ret = dwc3_core_init(&appledwc->dwc);
 		if (ret)
 			dev_err(appledwc->dev, "Failed to initialize DWC3 Core, err=%d\n", ret);
 		break;
 	default:
 		/* Unreachable unless there's a bug in this driver */
 		WARN_ON_ONCE(1);
 		ret = -EINVAL;
 		break;
 	}

 	return ret;
 }

 static void dwc3_apple_phy_set_mode(struct dwc3_apple *appledwc, enum phy_mode mode)
 {
 	lockdep_assert_held(&appledwc->lock);

 	/*
 	 * This platform requires SUSPHY to be enabled here already in order to properly configure
 	 * the PHY and switch dwc3's PIPE interface to USB3 PHY.
 	 */
 	dwc3_enable_susphy(&appledwc->dwc, true);
 	phy_set_mode(appledwc->dwc.usb2_generic_phy[0], mode);
 	phy_set_mode(appledwc->dwc.usb3_generic_phy[0], mode);
 }

 static int dwc3_apple_init(struct dwc3_apple *appledwc, enum dwc3_apple_state state)
 {
 	int ret, ret_reset;

 	lockdep_assert_held(&appledwc->lock);

 	ret = reset_control_deassert(appledwc->reset);
 	if (ret) {
 		dev_err(appledwc->dev, "Failed to deassert reset, err=%d\n", ret);
 		return ret;
 	}

 	ret = dwc3_apple_core_init(appledwc);
 	if (ret)
 		goto reset_assert;

 	/*
 	 * Now that the core is initialized and already went through dwc3_core_soft_reset we can
 	 * configure some unknown Apple-specific settings and then bring up xhci or gadget mode.
 	 */
 	dwc3_apple_setup_cio(appledwc);

 	switch (state) {
 	case DWC3_APPLE_HOST:
 		appledwc->dwc.dr_mode = USB_DR_MODE_HOST;
 		dwc3_apple_set_ptrcap(appledwc, DWC3_GCTL_PRTCAP_HOST);
 		dwc3_apple_phy_set_mode(appledwc, PHY_MODE_USB_HOST);
 		ret = dwc3_host_init(&appledwc->dwc);
 		if (ret) {
 			dev_err(appledwc->dev, "Failed to initialize host, ret=%d\n", ret);
 			goto core_exit;
 		}

 		break;
 	case DWC3_APPLE_DEVICE:
 		appledwc->dwc.dr_mode = USB_DR_MODE_PERIPHERAL;
 		dwc3_apple_set_ptrcap(appledwc, DWC3_GCTL_PRTCAP_DEVICE);
 		dwc3_apple_phy_set_mode(appledwc, PHY_MODE_USB_DEVICE);
 		ret = dwc3_gadget_init(&appledwc->dwc);
 		if (ret) {
 			dev_err(appledwc->dev, "Failed to initialize gadget, ret=%d\n", ret);
 			goto core_exit;
 		}
 		break;
 	default:
 		/* Unreachable unless there's a bug in this driver */
 		WARN_ON_ONCE(1);
 		ret = -EINVAL;
 		goto core_exit;
 	}

 	appledwc->state = state;
 	return 0;

 core_exit:
 	dwc3_core_exit(&appledwc->dwc);
 reset_assert:
 	ret_reset = reset_control_assert(appledwc->reset);
 	if (ret_reset)
 		dev_warn(appledwc->dev, "Failed to assert reset, err=%d\n", ret_reset);

 	return ret;
 }

 static int dwc3_apple_exit(struct dwc3_apple *appledwc)
 {
 	int ret = 0;

 	lockdep_assert_held(&appledwc->lock);

 	switch (appledwc->state) {
 	case DWC3_APPLE_PROBE_PENDING:
 	case DWC3_APPLE_NO_CABLE:
 		/* Nothing to do if we're already off */
 		return 0;
 	case DWC3_APPLE_DEVICE:
 		dwc3_gadget_exit(&appledwc->dwc);
 		break;
 	case DWC3_APPLE_HOST:
 		dwc3_host_exit(&appledwc->dwc);
 		break;
 	}

 	/*
 	 * This platform requires SUSPHY to be enabled in order to properly power down the PHY
 	 * and switch dwc3's PIPE interface back to a dummy PHY (i.e. no USB3 support and USB2 via
 	 * a different PHY connected through ULPI).
 	 */
 	dwc3_enable_susphy(&appledwc->dwc, true);
 	dwc3_core_exit(&appledwc->dwc);
 	appledwc->state = DWC3_APPLE_NO_CABLE;

 	ret = reset_control_assert(appledwc->reset);
 	if (ret) {
 		dev_err(appledwc->dev, "Failed to assert reset, err=%d\n", ret);
 		return ret;
 	}

 	return 0;
 }

 static int dwc3_usb_role_switch_set(struct usb_role_switch *sw, enum usb_role role)
 {
 	struct dwc3_apple *appledwc = usb_role_switch_get_drvdata(sw);
 	int ret;

 	guard(mutex)(&appledwc->lock);

 	/*
 	 * We need to tear all of dwc3 down and re-initialize it every time a cable is
 	 * connected or disconnected or when the mode changes. See the documentation for enum
 	 * dwc3_apple_state for details.
 	 */
 	ret = dwc3_apple_exit(appledwc);
 	if (ret)
 		return ret;

 	switch (role) {
 	case USB_ROLE_NONE:
 		/* Nothing to do if no cable is connected */
 		return 0;
 	case USB_ROLE_HOST:
 		return dwc3_apple_init(appledwc, DWC3_APPLE_HOST);
 	case USB_ROLE_DEVICE:
 		return dwc3_apple_init(appledwc, DWC3_APPLE_DEVICE);
 	default:
 		dev_err(appledwc->dev, "Invalid target role: %d\n", role);
 		return -EINVAL;
 	}
 }

 static enum usb_role dwc3_usb_role_switch_get(struct usb_role_switch *sw)
 {
 	struct dwc3_apple *appledwc = usb_role_switch_get_drvdata(sw);

 	guard(mutex)(&appledwc->lock);

 	switch (appledwc->state) {
 	case DWC3_APPLE_HOST:
 		return USB_ROLE_HOST;
 	case DWC3_APPLE_DEVICE:
 		return USB_ROLE_DEVICE;
 	case DWC3_APPLE_NO_CABLE:
 	case DWC3_APPLE_PROBE_PENDING:
 		return USB_ROLE_NONE;
 	default:
 		/* Unreachable unless there's a bug in this driver */
 		dev_err(appledwc->dev, "Invalid internal state: %d\n", appledwc->state);
 		return USB_ROLE_NONE;
 	}
 }

 static int dwc3_apple_setup_role_switch(struct dwc3_apple *appledwc)
 {
 	struct usb_role_switch_desc dwc3_role_switch = { NULL };

 	dwc3_role_switch.fwnode = dev_fwnode(appledwc->dev);
 	dwc3_role_switch.set = dwc3_usb_role_switch_set;
 	dwc3_role_switch.get = dwc3_usb_role_switch_get;
 	dwc3_role_switch.driver_data = appledwc;
 	appledwc->role_sw = usb_role_switch_register(appledwc->dev, &dwc3_role_switch);
 	if (IS_ERR(appledwc->role_sw))
 		return PTR_ERR(appledwc->role_sw);

 	return 0;
 }

 static int dwc3_apple_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct dwc3_apple *appledwc;
 	int ret;

 	appledwc = devm_kzalloc(&pdev->dev, sizeof(*appledwc), GFP_KERNEL);
 	if (!appledwc)
 		return -ENOMEM;

 	appledwc->dev = &pdev->dev;
 	mutex_init(&appledwc->lock);

 	appledwc->reset = devm_reset_control_get_exclusive(dev, NULL);
 	if (IS_ERR(appledwc->reset))
 		return dev_err_probe(&pdev->dev, PTR_ERR(appledwc->reset),
 				     "Failed to get reset control\n");

 	ret = reset_control_assert(appledwc->reset);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to assert reset, err=%d\n", ret);
 		return ret;
 	}

 	appledwc->mmio_resource = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dwc3-core");
 	if (!appledwc->mmio_resource) {
 		dev_err(dev, "Failed to get DWC3 MMIO\n");
 		return -EINVAL;
 	}

 	appledwc->apple_regs = devm_platform_ioremap_resource_byname(pdev, "dwc3-apple");
 	if (IS_ERR(appledwc->apple_regs))
 		return dev_err_probe(dev, PTR_ERR(appledwc->apple_regs),
 				     "Failed to map Apple-specific MMIO\n");

 	/*
 	 * On this platform, DWC3 can only be brought up after parts of the PHY have been
 	 * initialized with knowledge of the target mode and cable orientation from typec_set_mux.
 	 * Since this has not happened here we cannot setup DWC3 yet and instead defer this until
 	 * the first cable is connected. See the documentation for enum dwc3_apple_state for
 	 * details.
 	 */
 	appledwc->state = DWC3_APPLE_PROBE_PENDING;
 	ret = dwc3_apple_setup_role_switch(appledwc);
 	if (ret)
 		return dev_err_probe(&pdev->dev, ret, "Failed to setup role switch\n");

 	return 0;
 }

 static void dwc3_apple_remove(struct platform_device *pdev)
 {
 	struct dwc3 *dwc = platform_get_drvdata(pdev);
 	struct dwc3_apple *appledwc = to_dwc3_apple(dwc);

 	guard(mutex)(&appledwc->lock);

 	usb_role_switch_unregister(appledwc->role_sw);

 	/*
 	 * If we're still in DWC3_APPLE_PROBE_PENDING we never got any cable connected event and
 	 * dwc3_core_probe was never called and there's hence no need to call dwc3_core_remove.
 	 * dwc3_apple_exit can be called unconditionally because it checks the state itself.
 	 */
 	dwc3_apple_exit(appledwc);
 	if (appledwc->state != DWC3_APPLE_PROBE_PENDING)
 		dwc3_core_remove(&appledwc->dwc);
 }

 static const struct of_device_id dwc3_apple_of_match[] = {
 	{ .compatible = "apple,t8103-dwc3" },
 	{}
 };
 MODULE_DEVICE_TABLE(of, dwc3_apple_of_match);

 static struct platform_driver dwc3_apple_driver = {
 	.probe		= dwc3_apple_probe,
 	.remove		= dwc3_apple_remove,
 	.driver		= {
 		.name	= "dwc3-apple",
 		.of_match_table	= dwc3_apple_of_match,
 	},
 };

 module_platform_driver(dwc3_apple_driver);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Sven Peter <sven@kernel.org>");
 MODULE_DESCRIPTION("DesignWare DWC3 Apple Silicon Glue Driver");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Apple Silicon DWC3 Glue driver
	* Copyright (C) The Asahi Linux Contributors
	*
	* Based on:
	* - dwc3-qcom.c Copyright (c) 2018, The Linux Foundation. All rights reserved.
	* - dwc3-of-simple.c Copyright (c) 2015 Texas Instruments Incorporated - https://www.ti.com
	*/

	#include <linux/of.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/platform_device.h>
	#include <linux/reset.h>

	#include "glue.h"

	/*
	* This platform requires a very specific sequence of operations to bring up dwc3 and its USB3 PHY:
	*
	* 1) The PHY itself has to be brought up; for this we need to know the mode (USB3,
	* USB3+DisplayPort, USB4, etc) and the lane orientation. This happens through typec_mux_set.
	* 2) DWC3 has to be brought up but we must not touch the gadget area or start xhci yet.
	* 3) The PHY bring-up has to be finalized and dwc3's PIPE interface has to be switched to the
	* USB3 PHY, this is done inside phy_set_mode.
	* 4) We can now initialize xhci or gadget mode.
	*
	* We can switch 1 and 2 but 3 has to happen after (1 and 2) and 4 has to happen after 3.
	*
	* And then to bring this all down again:
	*
	* 1) DWC3 has to exit host or gadget mode and must no longer touch those registers
	* 2) The PHY has to switch dwc3's PIPE interface back to the dummy backend
	* 3) The PHY itself can be shut down, this happens from typec_mux_set
	*
	* We also can't transition the PHY from one mode to another while dwc3 is up and running (this is
	* slightly wrong, some transitions are possible, others aren't but because we have no documentation
	* for this I'd rather play it safe).
	*
	* After both the PHY and dwc3 are initialized we will only ever see a single "new device connected"
	* event. If we just keep them running only the first device plugged in will ever work. XHCI's port
	* status register actually does show the correct state but no interrupt ever comes in. In gadget
	* mode we don't even get a USBDisconnected event and everything looks like there's still something
	* connected on the other end.
	* This can be partially explained because the USB2 D+/D- lines are connected through a stateful
	* eUSB2 repeater which in turn is controlled by a variant of the TI TPS6598x USB PD chip which
	* resets the repeater out-of-band everytime the CC lines are (dis)connected. This then requires a
	* PHY reset to make sure the PHY and the eUSB2 repeater state are synchronized again.
	*
	* And to make this all extra fun: If we get the order of some of this wrong either the port is just
	* broken until a phy+dwc3 reset, or it's broken until a full SoC reset (likely because we can't
	* reset some parts of the PHY), or some watchdog kicks in after a few seconds and forces a full SoC
	* reset (mostly seen this with USB4/Thunderbolt but there's clearly some watchdog that hates
	* invalid states).
	*
	* Hence there's really no good way to keep dwc3 fully up and running after we disconnect a cable
	* because then we can't shut down the PHY anymore. And if we kept the PHY running in whatever mode
	* it was until the next cable is connected we'd need to tear it all down and bring it back up again
	* anyway to detect and use the next device.
	*
	* Instead, we just shut down everything when a cable is disconnected and transition to
	* DWC3_APPLE_NO_CABLE.
	* During initial probe we don't have any information about the connected cable and can't bring up
	* the PHY properly and thus also can't fully bring up dwc3. Instead, we just keep everything off
	* and defer the first dwc3 probe until we get the first cable connected event. Until then we stay
	* in DWC3_APPLE_PROBE_PENDING.
	* Once a cable is connected we then keep track of the controller mode here by transitioning to
	* DWC3_APPLE_HOST or DWC3_APPLE_DEVICE.
	*/
	enum dwc3_apple_state {
	DWC3_APPLE_PROBE_PENDING, /* Before first cable connection, dwc3_core_probe not called */
	DWC3_APPLE_NO_CABLE, /* No cable connected, dwc3 suspended after dwc3_core_exit */
	DWC3_APPLE_HOST, /* Cable connected, dwc3 in host mode */
	DWC3_APPLE_DEVICE, /* Cable connected, dwc3 in device mode */
	};

	/**
	* struct dwc3_apple - Apple-specific DWC3 USB controller
	* @dwc: Core DWC3 structure
	* @dev: Pointer to the device structure
	* @mmio_resource: Resource to be passed to dwc3_core_probe
	* @apple_regs: Apple-specific DWC3 registers
	* @reset: Reset control
	* @role_sw: USB role switch
	* @lock: Mutex for synchronizing access
	* @state: Current state of the controller, see documentation for the enum for details
	*/
	struct dwc3_apple {
	struct dwc3 dwc;

	struct device *dev;
	struct resource *mmio_resource;
	void __iomem *apple_regs;

	struct reset_control *reset;
	struct usb_role_switch *role_sw;

	struct mutex lock;

	enum dwc3_apple_state state;
	};

	#define to_dwc3_apple(d) container_of((d), struct dwc3_apple, dwc)

	/*
	* Apple Silicon dwc3 vendor-specific registers
	*
	* These registers were identified by tracing XNU's memory access patterns and correlating them with
	* debug output over serial to determine their names. We don't exactly know what these do but
	* without these USB3 devices sometimes don't work.
	*/
	#define APPLE_DWC3_REGS_START 0xcd00
	#define APPLE_DWC3_REGS_END 0xcdff

	#define APPLE_DWC3_CIO_LFPS_OFFSET 0xcd38
	#define APPLE_DWC3_CIO_LFPS_OFFSET_VALUE 0xf800f80

	#define APPLE_DWC3_CIO_BW_NGT_OFFSET 0xcd3c
	#define APPLE_DWC3_CIO_BW_NGT_OFFSET_VALUE 0xfc00fc0

	#define APPLE_DWC3_CIO_LINK_TIMER 0xcd40
	#define APPLE_DWC3_CIO_PENDING_HP_TIMER GENMASK(23, 16)
	#define APPLE_DWC3_CIO_PENDING_HP_TIMER_VALUE 0x14
	#define APPLE_DWC3_CIO_PM_LC_TIMER GENMASK(15, 8)
	#define APPLE_DWC3_CIO_PM_LC_TIMER_VALUE 0xa
	#define APPLE_DWC3_CIO_PM_ENTRY_TIMER GENMASK(7, 0)
	#define APPLE_DWC3_CIO_PM_ENTRY_TIMER_VALUE 0x10

	static inline void dwc3_apple_writel(struct dwc3_apple *appledwc, u32 offset, u32 value)
	{
	writel(value, appledwc->apple_regs + offset - APPLE_DWC3_REGS_START);
	}

	static inline u32 dwc3_apple_readl(struct dwc3_apple *appledwc, u32 offset)
	{
	return readl(appledwc->apple_regs + offset - APPLE_DWC3_REGS_START);
	}

	static inline void dwc3_apple_mask(struct dwc3_apple *appledwc, u32 offset, u32 mask, u32 value)
	{
	u32 reg;

	reg = dwc3_apple_readl(appledwc, offset);
	reg &= ~mask;
	reg \|= value;
	dwc3_apple_writel(appledwc, offset, reg);
	}

	static void dwc3_apple_setup_cio(struct dwc3_apple *appledwc)
	{
	dwc3_apple_writel(appledwc, APPLE_DWC3_CIO_LFPS_OFFSET, APPLE_DWC3_CIO_LFPS_OFFSET_VALUE);
	dwc3_apple_writel(appledwc, APPLE_DWC3_CIO_BW_NGT_OFFSET,
	APPLE_DWC3_CIO_BW_NGT_OFFSET_VALUE);
	dwc3_apple_mask(appledwc, APPLE_DWC3_CIO_LINK_TIMER, APPLE_DWC3_CIO_PENDING_HP_TIMER,
	FIELD_PREP(APPLE_DWC3_CIO_PENDING_HP_TIMER,
	APPLE_DWC3_CIO_PENDING_HP_TIMER_VALUE));
	dwc3_apple_mask(appledwc, APPLE_DWC3_CIO_LINK_TIMER, APPLE_DWC3_CIO_PM_LC_TIMER,
	FIELD_PREP(APPLE_DWC3_CIO_PM_LC_TIMER, APPLE_DWC3_CIO_PM_LC_TIMER_VALUE));
	dwc3_apple_mask(appledwc, APPLE_DWC3_CIO_LINK_TIMER, APPLE_DWC3_CIO_PM_ENTRY_TIMER,
	FIELD_PREP(APPLE_DWC3_CIO_PM_ENTRY_TIMER,
	APPLE_DWC3_CIO_PM_ENTRY_TIMER_VALUE));
	}

	static void dwc3_apple_set_ptrcap(struct dwc3_apple *appledwc, u32 mode)
	{
	guard(spinlock_irqsave)(&appledwc->dwc.lock);
	dwc3_set_prtcap(&appledwc->dwc, mode, false);
	}

	static int dwc3_apple_core_probe(struct dwc3_apple *appledwc)
	{
	struct dwc3_probe_data probe_data = {};
	int ret;

	lockdep_assert_held(&appledwc->lock);
	WARN_ON_ONCE(appledwc->state != DWC3_APPLE_PROBE_PENDING);

	appledwc->dwc.dev = appledwc->dev;
	probe_data.dwc = &appledwc->dwc;
	probe_data.res = appledwc->mmio_resource;
	probe_data.ignore_clocks_and_resets = true;
	probe_data.skip_core_init_mode = true;
	probe_data.properties = DWC3_DEFAULT_PROPERTIES;

	ret = dwc3_core_probe(&probe_data);
	if (ret)
	return ret;

	appledwc->state = DWC3_APPLE_NO_CABLE;
	return 0;
	}

	static int dwc3_apple_core_init(struct dwc3_apple *appledwc)
	{
	int ret;

	lockdep_assert_held(&appledwc->lock);

	switch (appledwc->state) {
	case DWC3_APPLE_PROBE_PENDING:
	ret = dwc3_apple_core_probe(appledwc);
	if (ret)
	dev_err(appledwc->dev, "Failed to probe DWC3 Core, err=%d\n", ret);
	break;
	case DWC3_APPLE_NO_CABLE:
	ret = dwc3_core_init(&appledwc->dwc);
	if (ret)
	dev_err(appledwc->dev, "Failed to initialize DWC3 Core, err=%d\n", ret);
	break;
	default:
	/* Unreachable unless there's a bug in this driver */
	WARN_ON_ONCE(1);
	ret = -EINVAL;
	break;
	}

	return ret;
	}

	static void dwc3_apple_phy_set_mode(struct dwc3_apple *appledwc, enum phy_mode mode)
	{
	lockdep_assert_held(&appledwc->lock);

	/*
	* This platform requires SUSPHY to be enabled here already in order to properly configure
	* the PHY and switch dwc3's PIPE interface to USB3 PHY.
	*/
	dwc3_enable_susphy(&appledwc->dwc, true);
	phy_set_mode(appledwc->dwc.usb2_generic_phy[0], mode);
	phy_set_mode(appledwc->dwc.usb3_generic_phy[0], mode);
	}

	static int dwc3_apple_init(struct dwc3_apple *appledwc, enum dwc3_apple_state state)
	{
	int ret, ret_reset;

	lockdep_assert_held(&appledwc->lock);

	ret = reset_control_deassert(appledwc->reset);
	if (ret) {
	dev_err(appledwc->dev, "Failed to deassert reset, err=%d\n", ret);
	return ret;
	}

	ret = dwc3_apple_core_init(appledwc);
	if (ret)
	goto reset_assert;

	/*
	* Now that the core is initialized and already went through dwc3_core_soft_reset we can
	* configure some unknown Apple-specific settings and then bring up xhci or gadget mode.
	*/
	dwc3_apple_setup_cio(appledwc);

	switch (state) {
	case DWC3_APPLE_HOST:
	appledwc->dwc.dr_mode = USB_DR_MODE_HOST;
	dwc3_apple_set_ptrcap(appledwc, DWC3_GCTL_PRTCAP_HOST);
	dwc3_apple_phy_set_mode(appledwc, PHY_MODE_USB_HOST);
	ret = dwc3_host_init(&appledwc->dwc);
	if (ret) {
	dev_err(appledwc->dev, "Failed to initialize host, ret=%d\n", ret);
	goto core_exit;
	}

	break;
	case DWC3_APPLE_DEVICE:
	appledwc->dwc.dr_mode = USB_DR_MODE_PERIPHERAL;
	dwc3_apple_set_ptrcap(appledwc, DWC3_GCTL_PRTCAP_DEVICE);
	dwc3_apple_phy_set_mode(appledwc, PHY_MODE_USB_DEVICE);
	ret = dwc3_gadget_init(&appledwc->dwc);
	if (ret) {
	dev_err(appledwc->dev, "Failed to initialize gadget, ret=%d\n", ret);
	goto core_exit;
	}
	break;
	default:
	/* Unreachable unless there's a bug in this driver */
	WARN_ON_ONCE(1);
	ret = -EINVAL;
	goto core_exit;
	}

	appledwc->state = state;
	return 0;

	core_exit:
	dwc3_core_exit(&appledwc->dwc);
	reset_assert:
	ret_reset = reset_control_assert(appledwc->reset);
	if (ret_reset)
	dev_warn(appledwc->dev, "Failed to assert reset, err=%d\n", ret_reset);

	return ret;
	}

	static int dwc3_apple_exit(struct dwc3_apple *appledwc)
	{
	int ret = 0;

	lockdep_assert_held(&appledwc->lock);

	switch (appledwc->state) {
	case DWC3_APPLE_PROBE_PENDING:
	case DWC3_APPLE_NO_CABLE:
	/* Nothing to do if we're already off */
	return 0;
	case DWC3_APPLE_DEVICE:
	dwc3_gadget_exit(&appledwc->dwc);
	break;
	case DWC3_APPLE_HOST:
	dwc3_host_exit(&appledwc->dwc);
	break;
	}

	/*
	* This platform requires SUSPHY to be enabled in order to properly power down the PHY
	* and switch dwc3's PIPE interface back to a dummy PHY (i.e. no USB3 support and USB2 via
	* a different PHY connected through ULPI).
	*/
	dwc3_enable_susphy(&appledwc->dwc, true);
	dwc3_core_exit(&appledwc->dwc);
	appledwc->state = DWC3_APPLE_NO_CABLE;

	ret = reset_control_assert(appledwc->reset);
	if (ret) {
	dev_err(appledwc->dev, "Failed to assert reset, err=%d\n", ret);
	return ret;
	}

	return 0;
	}

	static int dwc3_usb_role_switch_set(struct usb_role_switch *sw, enum usb_role role)
	{
	struct dwc3_apple *appledwc = usb_role_switch_get_drvdata(sw);
	int ret;

	guard(mutex)(&appledwc->lock);

	/*
	* We need to tear all of dwc3 down and re-initialize it every time a cable is
	* connected or disconnected or when the mode changes. See the documentation for enum
	* dwc3_apple_state for details.
	*/
	ret = dwc3_apple_exit(appledwc);
	if (ret)
	return ret;

	switch (role) {
	case USB_ROLE_NONE:
	/* Nothing to do if no cable is connected */
	return 0;
	case USB_ROLE_HOST:
	return dwc3_apple_init(appledwc, DWC3_APPLE_HOST);
	case USB_ROLE_DEVICE:
	return dwc3_apple_init(appledwc, DWC3_APPLE_DEVICE);
	default:
	dev_err(appledwc->dev, "Invalid target role: %d\n", role);
	return -EINVAL;
	}
	}

	static enum usb_role dwc3_usb_role_switch_get(struct usb_role_switch *sw)
	{
	struct dwc3_apple *appledwc = usb_role_switch_get_drvdata(sw);

	guard(mutex)(&appledwc->lock);

	switch (appledwc->state) {
	case DWC3_APPLE_HOST:
	return USB_ROLE_HOST;
	case DWC3_APPLE_DEVICE:
	return USB_ROLE_DEVICE;
	case DWC3_APPLE_NO_CABLE:
	case DWC3_APPLE_PROBE_PENDING:
	return USB_ROLE_NONE;
	default:
	/* Unreachable unless there's a bug in this driver */
	dev_err(appledwc->dev, "Invalid internal state: %d\n", appledwc->state);
	return USB_ROLE_NONE;
	}
	}

	static int dwc3_apple_setup_role_switch(struct dwc3_apple *appledwc)
	{
	struct usb_role_switch_desc dwc3_role_switch = { NULL };

	dwc3_role_switch.fwnode = dev_fwnode(appledwc->dev);
	dwc3_role_switch.set = dwc3_usb_role_switch_set;
	dwc3_role_switch.get = dwc3_usb_role_switch_get;
	dwc3_role_switch.driver_data = appledwc;
	appledwc->role_sw = usb_role_switch_register(appledwc->dev, &dwc3_role_switch);
	if (IS_ERR(appledwc->role_sw))
	return PTR_ERR(appledwc->role_sw);

	return 0;
	}

	static int dwc3_apple_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct dwc3_apple *appledwc;
	int ret;

	appledwc = devm_kzalloc(&pdev->dev, sizeof(*appledwc), GFP_KERNEL);
	if (!appledwc)
	return -ENOMEM;

	appledwc->dev = &pdev->dev;
	mutex_init(&appledwc->lock);

	appledwc->reset = devm_reset_control_get_exclusive(dev, NULL);
	if (IS_ERR(appledwc->reset))
	return dev_err_probe(&pdev->dev, PTR_ERR(appledwc->reset),
	"Failed to get reset control\n");

	ret = reset_control_assert(appledwc->reset);
	if (ret) {
	dev_err(&pdev->dev, "Failed to assert reset, err=%d\n", ret);
	return ret;
	}

	appledwc->mmio_resource = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dwc3-core");
	if (!appledwc->mmio_resource) {
	dev_err(dev, "Failed to get DWC3 MMIO\n");
	return -EINVAL;
	}

	appledwc->apple_regs = devm_platform_ioremap_resource_byname(pdev, "dwc3-apple");
	if (IS_ERR(appledwc->apple_regs))
	return dev_err_probe(dev, PTR_ERR(appledwc->apple_regs),
	"Failed to map Apple-specific MMIO\n");

	/*
	* On this platform, DWC3 can only be brought up after parts of the PHY have been
	* initialized with knowledge of the target mode and cable orientation from typec_set_mux.
	* Since this has not happened here we cannot setup DWC3 yet and instead defer this until
	* the first cable is connected. See the documentation for enum dwc3_apple_state for
	* details.
	*/
	appledwc->state = DWC3_APPLE_PROBE_PENDING;
	ret = dwc3_apple_setup_role_switch(appledwc);
	if (ret)
	return dev_err_probe(&pdev->dev, ret, "Failed to setup role switch\n");

	return 0;
	}

	static void dwc3_apple_remove(struct platform_device *pdev)
	{
	struct dwc3 *dwc = platform_get_drvdata(pdev);
	struct dwc3_apple *appledwc = to_dwc3_apple(dwc);

	guard(mutex)(&appledwc->lock);

	usb_role_switch_unregister(appledwc->role_sw);

	/*
	* If we're still in DWC3_APPLE_PROBE_PENDING we never got any cable connected event and
	* dwc3_core_probe was never called and there's hence no need to call dwc3_core_remove.
	* dwc3_apple_exit can be called unconditionally because it checks the state itself.
	*/
	dwc3_apple_exit(appledwc);
	if (appledwc->state != DWC3_APPLE_PROBE_PENDING)
	dwc3_core_remove(&appledwc->dwc);
	}

	static const struct of_device_id dwc3_apple_of_match[] = {
	{ .compatible = "apple,t8103-dwc3" },
	{}
	};
	MODULE_DEVICE_TABLE(of, dwc3_apple_of_match);

	static struct platform_driver dwc3_apple_driver = {
	.probe = dwc3_apple_probe,
	.remove = dwc3_apple_remove,
	.driver = {
	.name = "dwc3-apple",
	.of_match_table = dwc3_apple_of_match,
	},
	};

	module_platform_driver(dwc3_apple_driver);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Sven Peter <sven@kernel.org>");
	MODULE_DESCRIPTION("DesignWare DWC3 Apple Silicon Glue Driver");