From 162c595a0b4803505796349466f75167db2d6c88 Mon Sep 17 00:00:00 2001
From: Dominic Clifton <me@dominicclifton.name>
Date: Tue, 20 Jan 2026 22:37:00 +0100
Subject: [PATCH] KINETIS - Fix second USB stop and disconnect from crashing.

in qmk, there was startup code:

```
usbDisconnectBus(usbp);
usbStop(usbp);

wait_ms(50);

usbStart(usbp, &usbcfg);
usbConnectBus(usbp);
```

then later:
```
usbDisconnectBus(&USB_DRIVER);
usbStop(&USB_DRIVER);
```

This commit prevents crashes in the start/stop/connect/disconnect and ISRs for this sequence of calls.
---
 .../ports/KINETIS/LLD/USBHSv1/hal_usb_lld.c   | 70 ++++++++++++++++---
 .../ports/KINETIS/LLD/USBHSv1/hal_usb_lld.h   | 20 +++++-
 2 files changed, 78 insertions(+), 12 deletions(-)

diff --git a/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.c b/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.c
index 0fe261c5d0..65f1b5500d 100644
--- a/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.c
+++ b/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.c
@@ -211,6 +211,26 @@ void usb_packet_receive(USBDriver *usbp, usbep_t ep, size_t n)
  */
 OSAL_IRQ_HANDLER(KINETIS_USB_IRQ_VECTOR) {
   USBDriver *usbp = &USBD1;
+
+  /* Bail out if driver is stopped or being torn down */
+  if (usbp->state == USB_UNINIT || usbp->state == USB_STOP) {
+    uint8_t enabled =
+#if KINETIS_USB0_IS_USBOTG
+      (SIM->SCGC4 & SIM_SCGC4_USBOTG);
+#else
+      (SIM->SCGC4 & SIM_SCGC4_USBFS);
+#endif
+
+    if (enabled) {
+      /* Clear all pending USB IRQ flags */
+      USB0->ISTAT   = 0xFF;
+      USB0->ERRSTAT = 0xFF;
+    }
+    OSAL_IRQ_EPILOGUE();
+    return;
+  }
+
+
   uint8_t istat = USB0->ISTAT;
 
   OSAL_IRQ_PROLOGUE();
@@ -527,18 +547,50 @@ void usb_lld_start(USBDriver *usbp) {
  * @notapi
  */
 void usb_lld_stop(USBDriver *usbp) {
-  /* TODO: If in ready state then disables the USB clock.*/
-  if (usbp->state == USB_STOP) {
 #if KINETIS_USB_USE_USB0
-    if (&USBD1 == usbp) {
+    if (&USBD1 != usbp) return;
+
+    /* If the driver was never started, bail out */
+    if (usbp->state == USB_UNINIT || usbp->state == USB_STOP) {
+        return;
+    }
+
+    /* Mask all peripheral interrupts */
+    USB0->INTEN  = 0;
+    USB0->ERREN  = 0;
+
+    uint8_t enabled =
 #if KINETIS_USB0_IS_USBOTG
-      nvicDisableVector(USB_OTG_IRQn);
-#else /* KINETIS_USB0_IS_USBOTG */
-      nvicDisableVector(USB_IRQn);
-#endif /* KINETIS_USB0_IS_USBOTG */
+    (SIM->SCGC4 & SIM_SCGC4_USBOTG);
+#else
+    (SIM->SCGC4 & SIM_SCGC4_USBFS);
+#endif
+    if (enabled) {
+      /* Disconnect pull-up while clock is still on */
+      usb_lld_disconnect_bus(usbp);
+
+      /* Only disable USB engine if the clock is enabled */
+      USB0->CTL = 0;
+      USB0->CTL = USBx_CTL_ODDRST;   /* reset odd/even PID */
+      USB0->ISTAT   = 0xFF;
+      USB0->ERRSTAT = 0xFF;
     }
-#endif /* KINETIS_USB_USE_USB0 */
-  }
+
+    /* Disable NVIC IRQ */
+#if KINETIS_USB0_IS_USBOTG
+    nvicDisableVector(USB_OTG_IRQn);
+#else
+    nvicDisableVector(USB_IRQn);
+#endif
+
+    /* Gate the USB clock */
+#if KINETIS_USB0_IS_USBOTG
+    SIM->SCGC4 &= ~SIM_SCGC4_USBOTG;
+#else
+    SIM->SCGC4 &= ~SIM_SCGC4_USBFS;
+#endif
+
+#endif
 }
 
 /**
diff --git a/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.h b/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.h
index 05dd9c8c7f..38d16c7bfa 100644
--- a/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.h
+++ b/os/hal/ports/KINETIS/LLD/USBHSv1/hal_usb_lld.h
@@ -397,14 +397,28 @@ struct USBDriver {
  * @api
  */
 #if !defined(usb_lld_disconnect_bus)
-/* Writing to USB0->CONTROL causes an unhandled exception when USB module is not clocked. */
+
+/* Writing USB0->CONTROL with clock off causes hard fault on MK20 */
 #if KINETIS_USB0_IS_USBOTG
-#define usb_lld_disconnect_bus(usbp) if(SIM->SCGC4 & SIM_SCGC4_USBOTG) {USB0->CONTROL &= ~USBx_CONTROL_DPPULLUPNONOTG;} else {}
+#define usb_lld_disconnect_bus(usbp)                                   \
+  do {                                                                 \
+    (void)(usbp);                                                      \
+    if (SIM->SCGC4 & SIM_SCGC4_USBOTG) {                               \
+       USB0->CONTROL &= ~USBx_CONTROL_DPPULLUPNONOTG;                  \
+    }                                                                  \
+  } while (false)
 #else /* KINETIS_USB0_IS_USBOTG */
-#define usb_lld_disconnect_bus(usbp) if(SIM->SCGC4 & SIM_SCGC4_USBFS) {USB0->CONTROL &= ~USBx_CONTROL_DPPULLUPNONOTG;} else {}
+#define usb_lld_disconnect_bus(usbp)                                   \
+  do {                                                                 \
+    (void)(usbp);                                                      \
+    if (SIM->SCGC4 & SIM_SCGC4_USBFS) {                                \
+       USB0->CONTROL &= ~USBx_CONTROL_DPPULLUPNONOTG;                  \
+    }                                                                  \
+  } while (false)
 #endif /* KINETIS_USB0_IS_USBOTG */
 #endif
 
+
 /**
  * @brief   Start of host wake-up procedure.
  *