msm: kgsl: Use a bitmap allocator for global addressing

To prepare to allow global buffers to allocate a semi-random GPU address
move from a sequential allocator to a bitmap based one.

Change-Id: Ic0dedbadba36c4c7b7839528103997724eac7d6d
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Harshitha Sai Neelati <hsaine@codeaurora.org>

drivers/gpu/msm/kgsl_iommu.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2011-2018, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2011-2019, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -84,15 +84,8 @@ static struct kmem_cache *addr_entry_cache;
  *
  * Here we define an array and a simple allocator to keep track of the currently
  * active global entries. Each entry is assigned a unique address inside of a
- * MMU implementation specific "global" region. The addresses are assigned
+ * MMU implementation specific "global" region. We use a simple bitmap based
- * sequentially and never re-used to avoid having to go back and reprogram
+ * allocator for the region to allow for both fixed and dynamic addressing.
- * existing pagetables. The entire list of active entries are mapped and
- * unmapped into every new pagetable as it is created and destroyed.
- *
- * Because there are relatively few entries and they are defined at boot time we
- * don't need to go over the top to define a dynamic allocation scheme. It will
- * be less wasteful to pick a static number with a little bit of growth
- * potential.
  */
 
 #define GLOBAL_PT_ENTRIES 32
@@ -102,10 +95,12 @@ struct global_pt_entry {
 	char name[32];
 };
 
+#define GLOBAL_MAP_PAGES (KGSL_IOMMU_GLOBAL_MEM_SIZE >> PAGE_SHIFT)
+
 static struct global_pt_entry global_pt_entries[GLOBAL_PT_ENTRIES];
 static struct kgsl_memdesc *kgsl_global_secure_pt_entry;
+static DECLARE_BITMAP(global_map, GLOBAL_MAP_PAGES);
 static int global_pt_count;
-uint64_t global_pt_alloc;
 static struct kgsl_memdesc gpu_qdss_desc;
 static struct kgsl_memdesc gpu_qtimer_desc;
 
@@ -186,6 +181,12 @@ static void kgsl_iommu_remove_global(struct kgsl_mmu *mmu,
 
 	for (i = 0; i < global_pt_count; i++) {
 		if (global_pt_entries[i].memdesc == memdesc) {
+			u64 offset = memdesc->gpuaddr -
+				KGSL_IOMMU_GLOBAL_MEM_BASE(mmu);
+
+			bitmap_clear(global_map, offset >> PAGE_SHIFT,
+				kgsl_memdesc_footprint(memdesc) >> PAGE_SHIFT);
+
 			memdesc->gpuaddr = 0;
 			memdesc->priv &= ~KGSL_MEMDESC_GLOBAL;
 			global_pt_entries[i].memdesc = NULL;
@@ -197,15 +198,27 @@ static void kgsl_iommu_remove_global(struct kgsl_mmu *mmu,
 static void kgsl_iommu_add_global(struct kgsl_mmu *mmu,
 		struct kgsl_memdesc *memdesc, const char *name)
 {
+	int bit;
+	u64 size = kgsl_memdesc_footprint(memdesc);
+
 	if (memdesc->gpuaddr != 0)
 		return;
 
-	BUG_ON(global_pt_count >= GLOBAL_PT_ENTRIES);
+	if (WARN_ON(global_pt_count >= GLOBAL_PT_ENTRIES))
-	BUG_ON((global_pt_alloc + memdesc->size) >= KGSL_IOMMU_GLOBAL_MEM_SIZE);
+		return;
+
+	bit = bitmap_find_next_zero_area(global_map, GLOBAL_MAP_PAGES,
+		0, size >> PAGE_SHIFT, 0);
+
+	if (WARN_ON(bit >= GLOBAL_MAP_PAGES))
+		return;
+
+	memdesc->gpuaddr =
+		KGSL_IOMMU_GLOBAL_MEM_BASE(mmu) + (bit << PAGE_SHIFT);
+
+	bitmap_set(global_map, bit, size >> PAGE_SHIFT);
 
-	memdesc->gpuaddr = KGSL_IOMMU_GLOBAL_MEM_BASE(mmu) + global_pt_alloc;
 	memdesc->priv |= KGSL_MEMDESC_GLOBAL;
-	global_pt_alloc += memdesc->size;
 
 	global_pt_entries[global_pt_count].memdesc = memdesc;
 	strlcpy(global_pt_entries[global_pt_count].name, name,