drm/xe: Introduce a new DRM driver for Intel GPUs

Xe, is a new driver for Intel GPUs that supports both integrated and
discrete platforms starting with Tiger Lake (first Intel Xe Architecture).

The code is at a stage where it is already functional and has experimental
support for multiple platforms starting from Tiger Lake, with initial
support implemented in Mesa (for Iris and Anv, our OpenGL and Vulkan
drivers), as well as in NEO (for OpenCL and Level0).

The new Xe driver leverages a lot from i915.

As for display, the intent is to share the display code with the i915
driver so that there is maximum reuse there. But it is not added
in this patch.

This initial work is a collaboration of many people and unfortunately
the big squashed patch won't fully honor the proper credits. But let's
get some git quick stats so we can at least try to preserve some of the
credits:

Co-developed-by: Matthew Brost <matthew.brost@intel.com>
Co-developed-by: Matthew Auld <matthew.auld@intel.com>
Co-developed-by: Matt Roper <matthew.d.roper@intel.com>
Co-developed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Co-developed-by: Francois Dugast <francois.dugast@intel.com>
Co-developed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Co-developed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Co-developed-by: Philippe Lecluse <philippe.lecluse@intel.com>
Co-developed-by: Nirmoy Das <nirmoy.das@intel.com>
Co-developed-by: Jani Nikula <jani.nikula@intel.com>
Co-developed-by: José Roberto de Souza <jose.souza@intel.com>
Co-developed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Co-developed-by: Dave Airlie <airlied@redhat.com>
Co-developed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Co-developed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Co-developed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>

1 files changed, 161 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_pt_walk.h b/drivers/gpu/drm/xe/xe_pt_walk.h
new file mode 100644
index 000000000000..42c51fa601ec
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_pt_walk.h
@@ -0,0 +1,161 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+#ifndef __XE_PT_WALK__
+#define __XE_PT_WALK__
+
+#include <linux/pagewalk.h>
+#include <linux/types.h>
+
+struct xe_ptw_dir;
+
+/**
+ * struct xe_ptw - base class for driver pagetable subclassing.
+ * @dir: Pointer to an array of children if any.
+ *
+ * Drivers could subclass this, and if it's a page-directory, typically
+ * embed the xe_ptw_dir::entries array in the same allocation.
+ */
+struct xe_ptw {
+	struct xe_ptw_dir *dir;
+};
+
+/**
+ * struct xe_ptw_dir - page directory structure
+ * @entries: Array holding page directory children.
+ *
+ * It is the responsibility of the user to ensure @entries is
+ * correctly sized.
+ */
+struct xe_ptw_dir {
+	struct xe_ptw *entries[0];
+};
+
+/**
+ * struct xe_pt_walk - Embeddable struct for walk parameters
+ */
+struct xe_pt_walk {
+	/** @ops: The walk ops used for the pagewalk */
+	const struct xe_pt_walk_ops *ops;
+	/**
+	 * @shifts: Array of page-table entry shifts used for the
+	 * different levels, starting out with the leaf level 0
+	 * page-shift as the first entry. It's legal for this pointer to be
+	 * changed during the walk.
+	 */
+	const u64 *shifts;
+	/** @max_level: Highest populated level in @sizes */
+	unsigned int max_level;
+	/**
+	 * @shared_pt_mode: Whether to skip all entries that are private
+	 * to the address range and called only for entries that are
+	 * shared with other address ranges. Such entries are referred to
+	 * as shared pagetables.
+	 */
+	bool shared_pt_mode;
+};
+
+/**
+ * typedef xe_pt_entry_fn - gpu page-table-walk callback-function
+ * @parent: The parent page.table.
+ * @offset: The offset (number of entries) into the page table.
+ * @level: The level of @parent.
+ * @addr: The virtual address.
+ * @next: The virtual address for the next call, or end address.
+ * @child: Pointer to pointer to child page-table at this @offset. The
+ * function may modify the value pointed to if, for example, allocating a
+ * child page table.
+ * @action: The walk action to take upon return. See <linux/pagewalk.h>.
+ * @walk: The walk parameters.
+ */
+typedef int (*xe_pt_entry_fn)(struct xe_ptw *parent, pgoff_t offset,
+			      unsigned int level, u64 addr, u64 next,
+			      struct xe_ptw **child,
+			      enum page_walk_action *action,
+			      struct xe_pt_walk *walk);
+
+/**
+ * struct xe_pt_walk_ops - Walk callbacks.
+ */
+struct xe_pt_walk_ops {
+	/**
+	 * @pt_entry: Callback to be called for each page table entry prior
+	 * to descending to the next level. The returned value of the action
+	 * function parameter is honored.
+	 */
+	xe_pt_entry_fn pt_entry;
+	/**
+	 * @pt_post_descend: Callback to be called for each page table entry
+	 * after return from descending to the next level. The returned value
+	 * of the action function parameter is ignored.
+	 */
+	xe_pt_entry_fn pt_post_descend;
+};
+
+int xe_pt_walk_range(struct xe_ptw *parent, unsigned int level,
+		     u64 addr, u64 end, struct xe_pt_walk *walk);
+
+int xe_pt_walk_shared(struct xe_ptw *parent, unsigned int level,
+		      u64 addr, u64 end, struct xe_pt_walk *walk);
+
+/**
+ * xe_pt_covers - Whether the address range covers an entire entry in @level
+ * @addr: Start of the range.
+ * @end: End of range + 1.
+ * @level: Page table level.
+ * @walk: Page table walk info.
+ *
+ * This function is a helper to aid in determining whether a leaf page table
+ * entry can be inserted at this @level.
+ *
+ * Return: Whether the range provided covers exactly an entry at this level.
+ */
+static inline bool xe_pt_covers(u64 addr, u64 end, unsigned int level,
+				const struct xe_pt_walk *walk)
+{
+	u64 pt_size = 1ull << walk->shifts[level];
+
+	return end - addr == pt_size && IS_ALIGNED(addr, pt_size);
+}
+
+/**
+ * xe_pt_num_entries: Number of page-table entries of a given range at this
+ * level
+ * @addr: Start address.
+ * @end: End address.
+ * @level: Page table level.
+ * @walk: Walk info.
+ *
+ * Return: The number of page table entries at this level between @start and
+ * @end.
+ */
+static inline pgoff_t
+xe_pt_num_entries(u64 addr, u64 end, unsigned int level,
+		  const struct xe_pt_walk *walk)
+{
+	u64 pt_size = 1ull << walk->shifts[level];
+
+	return (round_up(end, pt_size) - round_down(addr, pt_size)) >>
+		walk->shifts[level];
+}
+
+/**
+ * xe_pt_offset: Offset of the page-table entry for a given address.
+ * @addr: The address.
+ * @level: Page table level.
+ * @walk: Walk info.
+ *
+ * Return: The page table entry offset for the given address in a
+ * page table with size indicated by @level.
+ */
+static inline pgoff_t
+xe_pt_offset(u64 addr, unsigned int level, const struct xe_pt_walk *walk)
+{
+	if (level < walk->max_level)
+		addr &= ((1ull << walk->shifts[level + 1]) - 1);
+
+	return addr >> walk->shifts[level];
+}
+
+#endif