soc/intel/cmn/xhci: Add function to reset the XHCI controller

This patch adds `xhci_host_reset()` to reset XHCI controller and the
scope of this function is with SMM hence, compiling xhci.c for SMM as
well.

Also, refactored `xhci.c` code to keep PCI enumeration within the scope
of `ramstage` alone hence, guarded with `ENV_RAMSTAGE` env_variable.

BUG=b:227289581
TEST=Able to perform a call from `xhci_host_reset` from S5 smi handler.

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: Ie0dc0a64044f291893931726d26c08c8b964a3cc
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63551
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/block/include/intelblocks/xhci.h

@@ -46,6 +46,8 @@ struct xhci_wake_info {
 bool xhci_update_wake_event(const struct xhci_wake_info *wake_info,
 			    size_t wake_info_count);
 
+/* xhci_host_reset() - Function to reset the host controller */
+void xhci_host_reset(void);
 void soc_xhci_init(struct device *dev);
 
 /*

src/soc/intel/common/block/xhci/Makefile.inc

@@ -1,4 +1,5 @@
 ramstage-$(CONFIG_SOC_INTEL_COMMON_BLOCK_XHCI) += xhci.c
 ramstage-$(CONFIG_SOC_INTEL_COMMON_BLOCK_XHCI_ELOG) += elog.c
 
+smm-$(CONFIG_SOC_INTEL_COMMON_BLOCK_XHCI) += xhci.c
 smm-$(CONFIG_SOC_INTEL_COMMON_BLOCK_XHCI_ELOG) += elog.c

src/soc/intel/common/block/xhci/xhci.c

@@ -13,9 +13,33 @@
 #define XHCI_USB2	2
 #define XHCI_USB3	3
 
+#define XHCI_USBCMD	0x80
+#define  USBCMD_HCRST	(1 << 1)
+
 /* Current Connect Status */
 #define XHCI_STATUS_CCS		(1 << 0)
 
+static uint8_t *xhci_mem_base(void)
+{
+	uint32_t mem_base = pci_read_config32(PCH_DEV_XHCI, PCI_BASE_ADDRESS_0);
+
+	/* Check if the controller is disabled or not present */
+	if (mem_base == 0 || mem_base == 0xffffffff)
+		return 0;
+
+	return (uint8_t *)(mem_base & ~PCI_BASE_ADDRESS_MEM_ATTR_MASK);
+}
+
+void xhci_host_reset(void)
+{
+	uint8_t *xhci_base = xhci_mem_base();
+	if (!xhci_base)
+		return;
+
+	setbits8(xhci_base + XHCI_USBCMD, USBCMD_HCRST);
+}
+
+#if ENV_RAMSTAGE
 static bool is_usb_port_connected(const struct xhci_usb_info *info,
 			unsigned int port_type, unsigned int port_id)
 {
@@ -134,3 +158,4 @@ static const struct pci_driver pch_usb_xhci __pci_driver = {
 	.vendor	 = PCI_VID_INTEL,
 	.devices	 = pci_device_ids,
 };
+#endif