device/xhci: Add xHCI utility to enumerate capabilities

This will allow enumerating an xHCI controller to allow dynamically
generating the ACPI device nodes.

BUG=b:154756391
TEST=Boot trembyle and see capabilities printed on console
xHCI Supported Protocol:
  Major: 0x2, Minor: 0x0, Protocol: 'USB '
  Port Offset: 1, Port Count: 2
xHCI Supported Protocol:
  Major: 0x3, Minor: 0x10, Protocol: 'USB '
  Port Offset: 3, Port Count: 1

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I3065c3fffad01b5378a55cfe904f971079b13d0f
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41899
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/device/Kconfig

@@ -811,4 +811,9 @@ config RESOURCE_ALLOCATOR_V4
 	  ranges for allocating resources. This allows allocation of resources
 	  above 4G boundary as well.
 
+config XHCI_UTILS
+	def_bool n
+	help
+	  Provides xHCI utility functions.
+
 endmenu

src/device/Makefile.inc

@@ -62,3 +62,5 @@ ramstage-y += mmio.c
 ramstage-y += resource_allocator_common.c
 ramstage-$(CONFIG_RESOURCE_ALLOCATOR_V3) += resource_allocator_v3.c
 ramstage-$(CONFIG_RESOURCE_ALLOCATOR_V4) += resource_allocator_v4.c
+
+ramstage-$(CONFIG_XHCI_UTILS) += xhci.c

src/device/xhci.c

@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <device/xhci.h>
+#include <console/console.h>
+#include <device/pci_def.h>
+#include <arch/mmio.h>
+
+union xhci_ext_caps_header {
+	uint32_t val;
+	struct {
+		uint32_t cap_id : 8;
+		uint32_t next_ptr : 8;
+		uint32_t reserved : 16;
+	};
+};
+
+enum cb_err xhci_for_each_ext_cap(const struct device *device, void *context,
+				  void (*callback)(void *context,
+						   const struct xhci_ext_cap *cap))
+{
+	struct resource *res;
+	uint32_t *ext_cap_ptr;
+	uint32_t ext_caps_word_offset;
+	union xhci_ext_caps_header header;
+	struct xhci_ext_cap cap;
+
+	if (!device || !callback)
+		return CB_ERR_ARG;
+
+	res = probe_resource(device, PCI_BASE_ADDRESS_0);
+	if (!res) {
+		printk(BIOS_ERR, "%s: Unable to find BAR resource for %s\n", __func__,
+		       dev_path(device));
+		return CB_ERR;
+	}
+
+	if (!(res->flags & IORESOURCE_ASSIGNED)) {
+		printk(BIOS_ERR, "%s: BAR is is not assigned\n", __func__);
+		return CB_ERR;
+	}
+
+	if (res->limit > 0xFFFFFFFF) {
+		printk(BIOS_ERR, "%s: 64-bit BAR is not supported\n", __func__);
+		return CB_ERR;
+	}
+
+	ext_caps_word_offset = read16(res2mmio(res, XHCI_HCCPARAMS1_XECP, 0));
+
+	if (!ext_caps_word_offset) {
+		printk(BIOS_ERR, "%s: No extended capabilities defined\n", __func__);
+		return CB_ERR;
+	}
+
+	ext_cap_ptr = res2mmio(res, ext_caps_word_offset << 2, 0);
+
+	while ((uintptr_t)ext_cap_ptr < (uintptr_t)res->limit) {
+		header.val = read32(ext_cap_ptr);
+
+		cap.cap_id = header.cap_id;
+
+		if (header.cap_id == XHCI_ECP_CAP_ID_SUPP) {
+			cap.supported_protocol.reg0 = header.val;
+			cap.supported_protocol.reg1 = read32(ext_cap_ptr + 1);
+			cap.supported_protocol.reg2 = read32(ext_cap_ptr + 2);
+		}
+
+		callback(context, &cap);
+
+		if (!header.next_ptr)
+			break;
+
+		ext_cap_ptr += header.next_ptr;
+	}
+
+	return CB_SUCCESS;
+}
+
+void xhci_print_supported_protocol(const struct xhci_supported_protocol *supported_protocol)
+{
+	printk(BIOS_DEBUG, "xHCI Supported Protocol:\n");
+	printk(BIOS_DEBUG, "  Major: %#x, Minor: %#x, Protocol: '%.*s'\n",
+	       supported_protocol->major_rev, supported_protocol->minor_rev,
+	       (int)sizeof(supported_protocol->name), supported_protocol->name);
+	printk(BIOS_DEBUG, "  Port Offset: %d, Port Count: %d\n",
+	       supported_protocol->port_offset, supported_protocol->port_count);
+}

src/include/device/xhci.h

@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __DEVICE_XHCI_H__
+#define __DEVICE_XHCI_H__
+
+#include <stdint.h>
+#include <device/device.h>
+#include <commonlib/bsd/cb_err.h>
+
+#define XHCI_HCCPARAMS1_XECP 0x12
+
+#define XHCI_ECP_CAP_ID_LEGACY 1
+#define XHCI_ECP_CAP_ID_SUPP 2
+
+struct xhci_supported_protocol {
+	union {
+		uint32_t reg0;
+		struct {
+			uint32_t cap_id : 8;
+			uint32_t next_ptr : 8;
+			uint32_t minor_rev : 8;
+			uint32_t major_rev : 8;
+		};
+	};
+	union {
+		uint32_t reg1;
+		char name[4];
+	};
+	union {
+		uint32_t reg2;
+		struct {
+			uint32_t port_offset : 8;
+			uint32_t port_count : 8;
+			uint32_t reserved : 12;
+			uint32_t protocol_speed_id_count : 4;
+		};
+	};
+};
+
+struct xhci_ext_cap {
+	uint32_t cap_id;
+	/* cap_id is used to select the correct struct in the union. */
+	union {
+		struct xhci_supported_protocol supported_protocol;
+	};
+};
+
+/**
+ * Iterates over the xHCI Extended Capabilities List.
+ */
+enum cb_err xhci_for_each_ext_cap(const struct device *device, void *context,
+				  void (*callback)(void *context,
+						   const struct xhci_ext_cap *cap));
+
+void xhci_print_supported_protocol(const struct xhci_supported_protocol *supported_protocol);
+
+#endif /* __DEVICE_XHCI_H__ */