x86/PCI: Add quirk for AMD XHCI controller that loses MSI-X state in D3hot

The AMD [1022:15b8] USB controller loses some internal functional MSI-X
context when transitioning from D0 to D3hot. BIOS normally traps D0->D3hot
and D3hot->D0 transitions so it can save and restore that internal context,
but some firmware in the field can't do this because it fails to clear the
AMD_15B8_RCC_DEV2_EPF0_STRAP2 NO_SOFT_RESET bit.

Clear AMD_15B8_RCC_DEV2_EPF0_STRAP2 NO_SOFT_RESET bit before USB controller
initialization during boot.

Link: https://lore.kernel.org/linux-usb/Y%2Fz9GdHjPyF2rNG3@glanzmann.de/T/#u
Link: https://lore.kernel.org/r/20230329172859.699743-1-Basavaraj.Natikar@amd.comReported-by: Thomas Glanzmann <thomas@glanzmann.de>
Tested-by: Thomas Glanzmann <thomas@glanzmann.de>
Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Cc: stable@vger.kernel.org

arch/x86/pci/fixup.c

@@ -7,6 +7,7 @@
 #include <linux/dmi.h>
 #include <linux/pci.h>
 #include <linux/vgaarb.h>
+#include <asm/amd_nb.h>
 #include <asm/hpet.h>
 #include <asm/pci_x86.h>
 
@@ -824,3 +825,23 @@ static void rs690_fix_64bit_dma(struct pci_dev *pdev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7910, rs690_fix_64bit_dma);
 
 #endif
+
+#ifdef CONFIG_AMD_NB
+
+#define AMD_15B8_RCC_DEV2_EPF0_STRAP2                                  0x10136008
+#define AMD_15B8_RCC_DEV2_EPF0_STRAP2_NO_SOFT_RESET_DEV2_F0_MASK       0x00000080L
+
+static void quirk_clear_strap_no_soft_reset_dev2_f0(struct pci_dev *dev)
+{
+	u32 data;
+
+	if (!amd_smn_read(0, AMD_15B8_RCC_DEV2_EPF0_STRAP2, &data)) {
+		data &= ~AMD_15B8_RCC_DEV2_EPF0_STRAP2_NO_SOFT_RESET_DEV2_F0_MASK;
+		if (amd_smn_write(0, AMD_15B8_RCC_DEV2_EPF0_STRAP2, data))
+			pci_err(dev, "Failed to write data 0x%x\n", data);
+	} else {
+		pci_err(dev, "Failed to read data\n");
+	}
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x15b8, quirk_clear_strap_no_soft_reset_dev2_f0);
+#endif