drivers/gpu/drm/i915/intel_acpi.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Intel ACPI functions
 *
 * _DSM related code stolen from nouveau_acpi.c.
 */
#include <linux/pci.h>
#include <linux/acpi.h>
#include <drm/drmP.h>
#include "i915_drv.h"

#define INTEL_DSM_REVISION_ID 1 /* For Calpella anyway... */
#define INTEL_DSM_FN_PLATFORM_MUX_INFO 1 /* No args */

static struct intel_dsm_priv {
	acpi_handle dhandle;
} intel_dsm_priv;

static const guid_t intel_dsm_guid =
	GUID_INIT(0x7ed873d3, 0xc2d0, 0x4e4f,
		  0xa8, 0x54, 0x0f, 0x13, 0x17, 0xb0, 0x1c, 0x2c);

static char *intel_dsm_port_name(u8 id)
{
	switch (id) {
	case 0:
		return "Reserved";
	case 1:
		return "Analog VGA";
	case 2:
		return "LVDS";
	case 3:
		return "Reserved";
	case 4:
		return "HDMI/DVI_B";
	case 5:
		return "HDMI/DVI_C";
	case 6:
		return "HDMI/DVI_D";
	case 7:
		return "DisplayPort_A";
	case 8:
		return "DisplayPort_B";
	case 9:
		return "DisplayPort_C";
	case 0xa:
		return "DisplayPort_D";
	case 0xb:
	case 0xc:
	case 0xd:
		return "Reserved";
	case 0xe:
		return "WiDi";
	default:
		return "bad type";
	}
}

static char *intel_dsm_mux_type(u8 type)
{
	switch (type) {
	case 0:
		return "unknown";
	case 1:
		return "No MUX, iGPU only";
	case 2:
		return "No MUX, dGPU only";
	case 3:
		return "MUXed between iGPU and dGPU";
	default:
		return "bad type";
	}
}

static void intel_dsm_platform_mux_info(void)
{
	int i;
	union acpi_object *pkg, *connector_count;

	pkg = acpi_evaluate_dsm_typed(intel_dsm_priv.dhandle, &intel_dsm_guid,
			INTEL_DSM_REVISION_ID, INTEL_DSM_FN_PLATFORM_MUX_INFO,
			NULL, ACPI_TYPE_PACKAGE);
	if (!pkg) {
		DRM_DEBUG_DRIVER("failed to evaluate _DSM\n");
		return;
	}

	connector_count = &pkg->package.elements[0];
	DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
		  (unsigned long long)connector_count->integer.value);
	for (i = 1; i < pkg->package.count; i++) {
		union acpi_object *obj = &pkg->package.elements[i];
		union acpi_object *connector_id = &obj->package.elements[0];
		union acpi_object *info = &obj->package.elements[1];
		DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
			  (unsigned long long)connector_id->integer.value);
		DRM_DEBUG_DRIVER("  port id: %s\n",
		       intel_dsm_port_name(info->buffer.pointer[0]));
		DRM_DEBUG_DRIVER("  display mux info: %s\n",
		       intel_dsm_mux_type(info->buffer.pointer[1]));
		DRM_DEBUG_DRIVER("  aux/dc mux info: %s\n",
		       intel_dsm_mux_type(info->buffer.pointer[2]));
		DRM_DEBUG_DRIVER("  hpd mux info: %s\n",
		       intel_dsm_mux_type(info->buffer.pointer[3]));
	}

	ACPI_FREE(pkg);
}

static bool intel_dsm_pci_probe(struct pci_dev *pdev)
{
	acpi_handle dhandle;

	dhandle = ACPI_HANDLE(&pdev->dev);
	if (!dhandle)
		return false;

	if (!acpi_check_dsm(dhandle, &intel_dsm_guid, INTEL_DSM_REVISION_ID,
			    1 << INTEL_DSM_FN_PLATFORM_MUX_INFO)) {
		DRM_DEBUG_KMS("no _DSM method for intel device\n");
		return false;
	}

	intel_dsm_priv.dhandle = dhandle;
	intel_dsm_platform_mux_info();

	return true;
}

static bool intel_dsm_detect(void)
{
	char acpi_method_name[255] = { 0 };
	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
	struct pci_dev *pdev = NULL;
	bool has_dsm = false;
	int vga_count = 0;

	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
		vga_count++;
		has_dsm |= intel_dsm_pci_probe(pdev);
	}

	if (vga_count == 2 && has_dsm) {
		acpi_get_name(intel_dsm_priv.dhandle, ACPI_FULL_PATHNAME, &buffer);
		DRM_DEBUG_DRIVER("vga_switcheroo: detected DSM switching method %s handle\n",
				 acpi_method_name);
		return true;
	}

	return false;
}

void intel_register_dsm_handler(void)
{
	if (!intel_dsm_detect())
		return;
}

void intel_unregister_dsm_handler(void)
{
}