diff options
Diffstat (limited to 'drivers/usb/dwc3/dwc3-apple.c')
| -rw-r--r-- | drivers/usb/dwc3/dwc3-apple.c | 489 |
1 files changed, 489 insertions, 0 deletions
diff --git a/drivers/usb/dwc3/dwc3-apple.c b/drivers/usb/dwc3/dwc3-apple.c new file mode 100644 index 000000000000..cc47cad232e3 --- /dev/null +++ b/drivers/usb/dwc3/dwc3-apple.c @@ -0,0 +1,489 @@ +// 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"); |