drm/xe: Prepare for running in different SR-IOV modes

We will be adding support for the SR-IOV and driver might be then
running, in addition to existing non-virtualized bare-metal mode,
also in Physical Function (PF) or Virtual Function (VF) mode.

Since these additional modes require some changes to the driver,
define enum flag to represent different SR-IOV modes and add a
function where we will detect the actual mode in the runtime.

We start with a forced bare-metal mode as it is sufficient to
enable basic functionality and ensures no impact to existing code.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20231115073804.1861-2-michal.wajdeczko@intel.com
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_sriov.c b/drivers/gpu/drm/xe/xe_sriov.c
new file mode 100644
index 000000000000..42a0e0c917a0
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_sriov.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#include "xe_assert.h"
+#include "xe_sriov.h"
+
+/**
+ * xe_sriov_mode_to_string - Convert enum value to string.
+ * @mode: the &xe_sriov_mode to convert
+ *
+ * Returns: SR-IOV mode as a user friendly string.
+ */
+const char *xe_sriov_mode_to_string(enum xe_sriov_mode mode)
+{
+	switch (mode) {
+	case XE_SRIOV_MODE_NONE:
+		return "none";
+	case XE_SRIOV_MODE_PF:
+		return "SR-IOV PF";
+	case XE_SRIOV_MODE_VF:
+		return "SR-IOV VF";
+	default:
+		return "<invalid>";
+	}
+}
+
+/**
+ * xe_sriov_probe_early - Probe a SR-IOV mode.
+ * @xe: the &xe_device to probe mode on
+ * @has_sriov: flag indicating hardware support for SR-IOV
+ *
+ * This function should be called only once and as soon as possible during
+ * driver probe to detect whether we are running a SR-IOV Physical Function
+ * (PF) or a Virtual Function (VF) device.
+ *
+ * SR-IOV PF mode detection is based on PCI @dev_is_pf() function.
+ * SR-IOV VF mode detection is based on dedicated MMIO register read.
+ */
+void xe_sriov_probe_early(struct xe_device *xe, bool has_sriov)
+{
+	enum xe_sriov_mode mode = XE_SRIOV_MODE_NONE;
+
+	/* TODO: replace with proper mode detection */
+	xe_assert(xe, !has_sriov);
+
+	xe_assert(xe, !xe->sriov.__mode);
+	xe->sriov.__mode = mode;
+	xe_assert(xe, xe->sriov.__mode);
+
+	if (has_sriov)
+		drm_info(&xe->drm, "Running in %s mode\n",
+			 xe_sriov_mode_to_string(xe_device_sriov_mode(xe)));
+}