[PATCH v4 3/3] usb: dwc3: invalidate dcache on buffer used in interrupt handling

[Neil Armstrong]

On Qualcomm systems, the setup buffer and even buffers are in
a bad state at interrupt handling, so invalidate the dcache lines
for the setup_buf and event buffer to make sure we read correct
data written by the hardware.

This fixes the following error:
dwc3-generic-peripheral usb at a600000: UNKNOWN IRQ type -1
dwc3-generic-peripheral usb at a600000: UNKNOWN IRQ type 4673109

and invalid situation in dwc3_gadget_giveback() because setup_buf content
is read at 0s and leads to fatal crash fixed by [1].

[1] https://lore.kernel.org/all/20240528-topic-sm8x50-dwc3-gadget-crash-fix-v1-1-58434ab4b3d3@linaro.org/

Reviewed-by: Mattijs Korpershoek <mkorpershoek at baylibre.com>
Signed-off-by: Neil Armstrong <neil.armstrong at linaro.org>
---
 drivers/usb/dwc3/ep0.c    | 2 ++
 drivers/usb/dwc3/gadget.c | 2 ++
 drivers/usb/dwc3/io.h     | 8 ++++++++
 3 files changed, 12 insertions(+)

diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 8ba5fcd5312..531f0b522af 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -742,6 +742,8 @@ static void dwc3_ep0_inspect_setup(struct dwc3 *dwc,
 	if (!dwc->gadget_driver)
 		goto out;
 
+	dwc3_invalidate_cache((uintptr_t)ctrl, sizeof(*ctrl));
+
 	len = le16_to_cpu(ctrl->wLength);
 	if (!len) {
 		dwc->three_stage_setup = false;
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 19c3a5f5e58..e5a383407a2 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2534,6 +2534,8 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3 *dwc, u32 buf)
 	while (left > 0) {
 		union dwc3_event event;
 
+		dwc3_invalidate_cache((uintptr_t)evt->buf, evt->length);
+
 		event.raw = *(u32 *) (evt->buf + evt->lpos);
 
 		dwc3_process_event_entry(dwc, &event);
diff --git a/drivers/usb/dwc3/io.h b/drivers/usb/dwc3/io.h
index 0ede323671b..c1ab0288142 100644
--- a/drivers/usb/dwc3/io.h
+++ b/drivers/usb/dwc3/io.h
@@ -55,4 +55,12 @@ static inline void dwc3_flush_cache(uintptr_t addr, int length)
 
 	flush_dcache_range((unsigned long)start_addr, (unsigned long)end_addr);
 }
+
+static inline void dwc3_invalidate_cache(uintptr_t addr, int length)
+{
+	uintptr_t start_addr = (uintptr_t)addr & ~(CACHELINE_SIZE - 1);
+	uintptr_t end_addr = ALIGN((uintptr_t)addr + length, CACHELINE_SIZE);
+
+	invalidate_dcache_range((unsigned long)start_addr, (unsigned long)end_addr);
+}
 #endif /* __DRIVERS_USB_DWC3_IO_H */

-- 
2.34.1