[PATCH] usb: xhci-pci: Raspberry Pi FW loader for VIA VL805

[Nicolas Saenz Julienne]

On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be
loaded directly from an EEPROM or, if not present, by the SoC's
VideCore.  Inform VideCore that VL805 was just reset, or defer xhci's
probe if not yet joinable trough the mailbox interface.

Based on Tim Gover's downstream implementation.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
---
 drivers/usb/host/xhci-pci.c                | 50 ++++++++++++++++++++++
 include/soc/bcm2835/raspberrypi-firmware.h |  2 +-
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 4917c5b033fa..eadace4a9339 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -13,6 +13,8 @@
 #include <linux/module.h>
 #include <linux/acpi.h>
 
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
 #include "xhci.h"
 #include "xhci-trace.h"
 
@@ -308,6 +310,44 @@ static int xhci_pci_setup(struct usb_hcd *hcd)
 	return xhci_pci_reinit(xhci, pdev);
 }
 
+/*
+ * On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be
+ * loaded directly from an EEPROM or, if not present, by the SoC's VideCore.
+ * Inform VideCore that VL805 was just reset, or defer xhci's probe if not yet
+ * joinable trough the mailbox interface.
+ */
+static int raspberrypi_load_vl805_fw(struct pci_dev *pdev)
+{
+#ifdef CONFIG_RASPBERRYPI_FIRMWARE
+	struct device_node *fw_np;
+	struct rpi_firmware *fw;
+	u32 dev_addr;
+	int ret;
+
+	fw_np = of_find_compatible_node(NULL, NULL,
+					"raspberrypi,bcm2835-firmware");
+	if (!fw_np)
+		return 0;
+
+	fw = rpi_firmware_get(fw_np);
+	of_node_put(fw_np);
+	if (!fw)
+		return -EPROBE_DEFER;
+
+	dev_addr = pdev->bus->number << 20 | PCI_SLOT(pdev->devfn) << 15 |
+		   PCI_FUNC(pdev->devfn) << 12;
+
+	ret = rpi_firmware_property(fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,
+				    &dev_addr, sizeof(dev_addr));
+	if (ret)
+		return ret;
+
+	dev_dbg(&pdev->dev, "loaded Raspberry Pi's VL805 firmware\n");
+
+#endif
+	return 0;
+}
+
 /*
  * We need to register our own PCI probe function (instead of the USB core's
  * function) in order to create a second roothub under xHCI.
@@ -321,6 +361,16 @@ static int xhci_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 
 	driver = (struct hc_driver *)id->driver_data;
 
+	if (dev->vendor == PCI_VENDOR_ID_VIA && dev->device == 0x3483) {
+		retval = raspberrypi_load_vl805_fw(dev);
+		if (retval) {
+			if (retval != -EPROBE_DEFER)
+				dev_err(&dev->dev,
+					"Failed to load VL805's firmware");
+			return retval;
+		}
+	}
+
 	/* Prevent runtime suspending between USB-2 and USB-3 initialization */
 	pm_runtime_get_noresume(&dev->dev);
 
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index 7800e12ee042..cc9cdbc66403 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -90,7 +90,7 @@ enum rpi_firmware_property_tag {
 	RPI_FIRMWARE_SET_PERIPH_REG =                         0x00038045,
 	RPI_FIRMWARE_GET_POE_HAT_VAL =                        0x00030049,
 	RPI_FIRMWARE_SET_POE_HAT_VAL =                        0x00030050,
-
+	RPI_FIRMWARE_NOTIFY_XHCI_RESET =                      0x00030058,
 
 	/* Dispmanx TAGS */
 	RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE =                   0x00040001,
-- 
2.25.0