drm/nouveau/instmem/gk20a: use DMA API CPU mapping

Commit 69c49382 ("drm/nouveau/instmem/gk20a: use direct CPU access")
tried to be smart while using the DMA-API by managing the CPU mappings of
buffers allocated with the DMA-API by itself. In doing so, it relied
on dma_to_phys() which is an architecture-private function not
available everywhere. This broke the build on several architectures.

Since there is no reliable and portable way to obtain the physical
address of a DMA-API buffer, stop trying to be smart and just use the
CPU mapping that the DMA-API can provide. This means that buffers will
be CPU-mapped for all their life as opposed to when we need them, but
anyway using the DMA-API here is a fallback for when no IOMMU is
available so we should not expect optimal behavior.

This makes the IOMMU and DMA-API implementations of instmem diverge
enough that we should maybe put them into separate files...
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c

@@ -56,9 +56,6 @@ struct gk20a_instobj {
 
 	/* CPU mapping */
 	u32 *vaddr;
-	struct list_head vaddr_node;
-	/* How many clients are using vaddr? */
-	u32 use_cpt;
 };
 #define gk20a_instobj(p) container_of((p), struct gk20a_instobj, memory)
 
@@ -68,7 +65,6 @@ struct gk20a_instobj {
 struct gk20a_instobj_dma {
 	struct gk20a_instobj base;
 
-	u32 *cpuaddr;
 	dma_addr_t handle;
 	struct nvkm_mm_node r;
 };
@@ -81,6 +77,11 @@ struct gk20a_instobj_dma {
 struct gk20a_instobj_iommu {
 	struct gk20a_instobj base;
 
+	/* to link into gk20a_instmem::vaddr_lru */
+	struct list_head vaddr_node;
+	/* how many clients are using vaddr? */
+	u32 use_cpt;
+
 	/* will point to the higher half of pages */
 	dma_addr_t *dma_addrs;
 	/* array of base.mem->size pages (+ dma_addr_ts) */
@@ -109,8 +110,6 @@ struct gk20a_instmem {
 
 	/* Only used by DMA API */
 	struct dma_attrs attrs;
-
-	void __iomem * (*cpu_map)(struct nvkm_memory *);
 };
 #define gk20a_instmem(p) container_of((p), struct gk20a_instmem, base)
 
@@ -132,52 +131,19 @@ gk20a_instobj_size(struct nvkm_memory *memory)
 	return (u64)gk20a_instobj(memory)->mem.size << 12;
 }
 
-static void __iomem *
-gk20a_instobj_cpu_map_dma(struct nvkm_memory *memory)
-{
-#if defined(CONFIG_ARM) || defined(CONFIG_ARM64)
-	struct gk20a_instobj_dma *node = gk20a_instobj_dma(memory);
-	struct device *dev = node->base.imem->base.subdev.device->dev;
-	int npages = nvkm_memory_size(memory) >> 12;
-	struct page *pages[npages];
-	int i;
-
-	/* we shouldn't see a gk20a on anything but arm/arm64 anyways */
-	/* phys_to_page does not exist on all platforms... */
-	pages[0] = pfn_to_page(dma_to_phys(dev, node->handle) >> PAGE_SHIFT);
-	for (i = 1; i < npages; i++)
-		pages[i] = pages[0] + i;
-
-	return vmap(pages, npages, VM_MAP, pgprot_writecombine(PAGE_KERNEL));
-#else
-	BUG();
-	return NULL;
-#endif
-}
-
-static void __iomem *
-gk20a_instobj_cpu_map_iommu(struct nvkm_memory *memory)
-{
-	struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
-	int npages = nvkm_memory_size(memory) >> 12;
-
-	return vmap(node->pages, npages, VM_MAP,
-		    pgprot_writecombine(PAGE_KERNEL));
-}
-
 /*
  * Recycle the vaddr of obj. Must be called with gk20a_instmem::lock held.
  */
 static void
-gk20a_instobj_recycle_vaddr(struct gk20a_instobj *obj)
+gk20a_instobj_iommu_recycle_vaddr(struct gk20a_instobj_iommu *obj)
 {
-	struct gk20a_instmem *imem = obj->imem;
+	struct gk20a_instmem *imem = obj->base.imem;
 	/* there should not be any user left... */
 	WARN_ON(obj->use_cpt);
 	list_del(&obj->vaddr_node);
-	vunmap(obj->vaddr);
-	obj->vaddr = NULL;
-	imem->vaddr_use -= nvkm_memory_size(&obj->memory);
+	vunmap(obj->base.vaddr);
+	obj->base.vaddr = NULL;
+	imem->vaddr_use -= nvkm_memory_size(&obj->base.memory);
 	nvkm_debug(&imem->base.subdev, "vaddr used: %x/%x\n", imem->vaddr_use,
 		   imem->vaddr_max);
 }
@@ -193,17 +159,30 @@ gk20a_instmem_vaddr_gc(struct gk20a_instmem *imem, const u64 size)
 		if (list_empty(&imem->vaddr_lru))
 			break;
 
-		gk20a_instobj_recycle_vaddr(list_first_entry(&imem->vaddr_lru,
-					     struct gk20a_instobj, vaddr_node));
+		gk20a_instobj_iommu_recycle_vaddr(
+				list_first_entry(&imem->vaddr_lru,
+				struct gk20a_instobj_iommu, vaddr_node));
 	}
 }
 
 static void __iomem *
-gk20a_instobj_acquire(struct nvkm_memory *memory)
+gk20a_instobj_acquire_dma(struct nvkm_memory *memory)
 {
 	struct gk20a_instobj *node = gk20a_instobj(memory);
 	struct gk20a_instmem *imem = node->imem;
 	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
+
+	nvkm_ltc_flush(ltc);
+
+	return node->vaddr;
+}
+
+static void __iomem *
+gk20a_instobj_acquire_iommu(struct nvkm_memory *memory)
+{
+	struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
+	struct gk20a_instmem *imem = node->base.imem;
+	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
 	const u64 size = nvkm_memory_size(memory);
 	unsigned long flags;
 
@@ -211,7 +190,7 @@ gk20a_instobj_acquire(struct nvkm_memory *memory)
 
 	spin_lock_irqsave(&imem->lock, flags);
 
-	if (node->vaddr) {
+	if (node->base.vaddr) {
 		if (!node->use_cpt) {
 			/* remove from LRU list since mapping in use again */
 			list_del(&node->vaddr_node);
@@ -222,9 +201,10 @@ gk20a_instobj_acquire(struct nvkm_memory *memory)
 	/* try to free some address space if we reached the limit */
 	gk20a_instmem_vaddr_gc(imem, size);
 
-	node->vaddr = imem->cpu_map(memory);
-
-	if (!node->vaddr) {
+	/* map the pages */
+	node->base.vaddr = vmap(node->pages, size >> PAGE_SHIFT, VM_MAP,
+				pgprot_writecombine(PAGE_KERNEL));
+	if (!node->base.vaddr) {
 		nvkm_error(&imem->base.subdev, "cannot map instobj - "
 			   "this is not going to end well...\n");
 		goto out;
@@ -238,15 +218,25 @@ gk20a_instobj_acquire(struct nvkm_memory *memory)
 	node->use_cpt++;
 	spin_unlock_irqrestore(&imem->lock, flags);
 
-	return node->vaddr;
+	return node->base.vaddr;
 }
 
 static void
-gk20a_instobj_release(struct nvkm_memory *memory)
+gk20a_instobj_release_dma(struct nvkm_memory *memory)
 {
 	struct gk20a_instobj *node = gk20a_instobj(memory);
 	struct gk20a_instmem *imem = node->imem;
 	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
+
+	nvkm_ltc_invalidate(ltc);
+}
+
+static void
+gk20a_instobj_release_iommu(struct nvkm_memory *memory)
+{
+	struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
+	struct gk20a_instmem *imem = node->base.imem;
+	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
 	unsigned long flags;
 
 	spin_lock_irqsave(&imem->lock, flags);
@@ -290,27 +280,6 @@ gk20a_instobj_map(struct nvkm_memory *memory, struct nvkm_vma *vma, u64 offset)
 	nvkm_vm_map_at(vma, offset, &node->mem);
 }
 
-/*
- * Clear the CPU mapping of an instobj if it exists
- */
-static void
-gk20a_instobj_dtor(struct gk20a_instobj *node)
-{
-	struct gk20a_instmem *imem = node->imem;
-	unsigned long flags;
-
-	spin_lock_irqsave(&imem->lock, flags);
-
-	/* vaddr has already been recycled */
-	if (!node->vaddr)
-		goto out;
-
-	gk20a_instobj_recycle_vaddr(node);
-
-out:
-	spin_unlock_irqrestore(&imem->lock, flags);
-}
-
 static void *
 gk20a_instobj_dtor_dma(struct nvkm_memory *memory)
 {
@@ -318,12 +287,10 @@ gk20a_instobj_dtor_dma(struct nvkm_memory *memory)
 	struct gk20a_instmem *imem = node->base.imem;
 	struct device *dev = imem->base.subdev.device->dev;
 
-	gk20a_instobj_dtor(&node->base);
-
-	if (unlikely(!node->cpuaddr))
+	if (unlikely(!node->base.vaddr))
 		goto out;
 
-	dma_free_attrs(dev, node->base.mem.size << PAGE_SHIFT, node->cpuaddr,
+	dma_free_attrs(dev, node->base.mem.size << PAGE_SHIFT, node->base.vaddr,
 		       node->handle, &imem->attrs);
 
 out:
@@ -337,13 +304,20 @@ gk20a_instobj_dtor_iommu(struct nvkm_memory *memory)
 	struct gk20a_instmem *imem = node->base.imem;
 	struct device *dev = imem->base.subdev.device->dev;
 	struct nvkm_mm_node *r;
+	unsigned long flags;
 	int i;
 
-	gk20a_instobj_dtor(&node->base);
-
 	if (unlikely(list_empty(&node->base.mem.regions)))
 		goto out;
 
+	spin_lock_irqsave(&imem->lock, flags);
+
+	/* vaddr has already been recycled */
+	if (node->base.vaddr)
+		gk20a_instobj_iommu_recycle_vaddr(node);
+
+	spin_unlock_irqrestore(&imem->lock, flags);
+
 	r = list_first_entry(&node->base.mem.regions, struct nvkm_mm_node,
 			     rl_entry);
 
@@ -374,8 +348,8 @@ gk20a_instobj_func_dma = {
 	.target = gk20a_instobj_target,
 	.addr = gk20a_instobj_addr,
 	.size = gk20a_instobj_size,
-	.acquire = gk20a_instobj_acquire,
-	.release = gk20a_instobj_release,
+	.acquire = gk20a_instobj_acquire_dma,
+	.release = gk20a_instobj_release_dma,
 	.rd32 = gk20a_instobj_rd32,
 	.wr32 = gk20a_instobj_wr32,
 	.map = gk20a_instobj_map,
@@ -387,8 +361,8 @@ gk20a_instobj_func_iommu = {
 	.target = gk20a_instobj_target,
 	.addr = gk20a_instobj_addr,
 	.size = gk20a_instobj_size,
-	.acquire = gk20a_instobj_acquire,
-	.release = gk20a_instobj_release,
+	.acquire = gk20a_instobj_acquire_iommu,
+	.release = gk20a_instobj_release_iommu,
 	.rd32 = gk20a_instobj_rd32,
 	.wr32 = gk20a_instobj_wr32,
 	.map = gk20a_instobj_map,
@@ -408,10 +382,10 @@ gk20a_instobj_ctor_dma(struct gk20a_instmem *imem, u32 npages, u32 align,
 
 	nvkm_memory_ctor(&gk20a_instobj_func_dma, &node->base.memory);
 
-	node->cpuaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
-					&node->handle, GFP_KERNEL,
-					&imem->attrs);
-	if (!node->cpuaddr) {
+	node->base.vaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
+					   &node->handle, GFP_KERNEL,
+					   &imem->attrs);
+	if (!node->base.vaddr) {
 		nvkm_error(subdev, "cannot allocate DMA memory\n");
 		return -ENOMEM;
 	}
@@ -617,18 +591,14 @@ gk20a_instmem_new(struct nvkm_device *device, int index,
 		imem->mm = &tdev->iommu.mm;
 		imem->domain = tdev->iommu.domain;
 		imem->iommu_pgshift = tdev->iommu.pgshift;
-		imem->cpu_map = gk20a_instobj_cpu_map_iommu;
 		imem->iommu_bit = tdev->func->iommu_bit;
 
 		nvkm_info(&imem->base.subdev, "using IOMMU\n");
 	} else {
 		init_dma_attrs(&imem->attrs);
-		/* We will access the memory through our own mapping */
 		dma_set_attr(DMA_ATTR_NON_CONSISTENT, &imem->attrs);
 		dma_set_attr(DMA_ATTR_WEAK_ORDERING, &imem->attrs);
 		dma_set_attr(DMA_ATTR_WRITE_COMBINE, &imem->attrs);
-		dma_set_attr(DMA_ATTR_NO_KERNEL_MAPPING, &imem->attrs);
-		imem->cpu_map = gk20a_instobj_cpu_map_dma;
 
 		nvkm_info(&imem->base.subdev, "using DMA API\n");
 	}