[PATCH v6 2/2] drm/msm/a6xx: Use the DMA API for GMU memory objects

[Jordan Crouse]

The GMU has very few memory allocations and uses a flat memory space so
there is no good reason to go out of our way to bypass the DMA APIs which
were basically designed for this exact scenario.

v7: Check return value of dma_set_mask_and_coherent
v4: Use dma_alloc_wc()
v3: Set the dma mask correctly and use dma_addr_t for the iova type
v2: Pass force_dma false to of_dma_configure to require that the DMA
region be set up and return error from of_dma_configure to fail probe.

Reviewed-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Signed-off-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
---

 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 115 +++-----------------------
 drivers/gpu/drm/msm/adreno/a6xx_gmu.h |   6 +-
 2 files changed, 14 insertions(+), 107 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index 748cd379065f..c4e71abbdd53 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -2,6 +2,7 @@
 /* Copyright (c) 2017-2019 The Linux Foundation. All rights reserved. */
 
 #include <linux/clk.h>
+#include <linux/dma-mapping.h>
 #include <linux/interconnect.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_opp.h>
@@ -920,21 +921,10 @@ int a6xx_gmu_stop(struct a6xx_gpu *a6xx_gpu)
 
 static void a6xx_gmu_memory_free(struct a6xx_gmu *gmu, struct a6xx_gmu_bo *bo)
 {
-	int count, i;
-	u64 iova;
-
 	if (IS_ERR_OR_NULL(bo))
 		return;
 
-	count = bo->size >> PAGE_SHIFT;
-	iova = bo->iova;
-
-	for (i = 0; i < count; i++, iova += PAGE_SIZE) {
-		iommu_unmap(gmu->domain, iova, PAGE_SIZE);
-		__free_pages(bo->pages[i], 0);
-	}
-
-	kfree(bo->pages);
+	dma_free_wc(gmu->dev, bo->size, bo->virt, bo->iova);
 	kfree(bo);
 }
 
@@ -942,7 +932,6 @@ static struct a6xx_gmu_bo *a6xx_gmu_memory_alloc(struct a6xx_gmu *gmu,
 		size_t size)
 {
 	struct a6xx_gmu_bo *bo;
-	int ret, count, i;
 
 	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
 	if (!bo)
@@ -950,86 +939,14 @@ static struct a6xx_gmu_bo *a6xx_gmu_memory_alloc(struct a6xx_gmu *gmu,
 
 	bo->size = PAGE_ALIGN(size);
 
-	count = bo->size >> PAGE_SHIFT;
+	bo->virt = dma_alloc_wc(gmu->dev, bo->size, &bo->iova, GFP_KERNEL);
 
-	bo->pages = kcalloc(count, sizeof(struct page *), GFP_KERNEL);
-	if (!bo->pages) {
+	if (!bo->virt) {
 		kfree(bo);
 		return ERR_PTR(-ENOMEM);
 	}
 
-	for (i = 0; i < count; i++) {
-		bo->pages[i] = alloc_page(GFP_KERNEL);
-		if (!bo->pages[i])
-			goto err;
-	}
-
-	bo->iova = gmu->uncached_iova_base;
-
-	for (i = 0; i < count; i++) {
-		ret = iommu_map(gmu->domain,
-			bo->iova + (PAGE_SIZE * i),
-			page_to_phys(bo->pages[i]), PAGE_SIZE,
-			IOMMU_READ | IOMMU_WRITE);
-
-		if (ret) {
-			DRM_DEV_ERROR(gmu->dev, "Unable to map GMU buffer object\n");
-
-			for (i = i - 1 ; i >= 0; i--)
-				iommu_unmap(gmu->domain,
-					bo->iova + (PAGE_SIZE * i),
-					PAGE_SIZE);
-
-			goto err;
-		}
-	}
-
-	bo->virt = vmap(bo->pages, count, VM_IOREMAP,
-		pgprot_writecombine(PAGE_KERNEL));
-	if (!bo->virt)
-		goto err;
-
-	/* Align future IOVA addresses on 1MB boundaries */
-	gmu->uncached_iova_base += ALIGN(size, SZ_1M);
-
 	return bo;
-
-err:
-	for (i = 0; i < count; i++) {
-		if (bo->pages[i])
-			__free_pages(bo->pages[i], 0);
-	}
-
-	kfree(bo->pages);
-	kfree(bo);
-
-	return ERR_PTR(-ENOMEM);
-}
-
-static int a6xx_gmu_memory_probe(struct a6xx_gmu *gmu)
-{
-	int ret;
-
-	/*
-	 * The GMU address space is hardcoded to treat the range
-	 * 0x60000000 - 0x80000000 as un-cached memory. All buffers shared
-	 * between the GMU and the CPU will live in this space
-	 */
-	gmu->uncached_iova_base = 0x60000000;
-
-
-	gmu->domain = iommu_domain_alloc(&platform_bus_type);
-	if (!gmu->domain)
-		return -ENODEV;
-
-	ret = iommu_attach_device(gmu->domain, gmu->dev);
-
-	if (ret) {
-		iommu_domain_free(gmu->domain);
-		gmu->domain = NULL;
-	}
-
-	return ret;
 }
 
 /* Return the 'arc-level' for the given frequency */
@@ -1289,10 +1206,6 @@ void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu)
 
 	a6xx_gmu_memory_free(gmu, gmu->hfi);
 
-	iommu_detach_device(gmu->domain, gmu->dev);
-
-	iommu_domain_free(gmu->domain);
-
 	free_irq(gmu->gmu_irq, gmu);
 	free_irq(gmu->hfi_irq, gmu);
 
@@ -1313,7 +1226,15 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
 
 	gmu->dev = &pdev->dev;
 
-	of_dma_configure(gmu->dev, node, true);
+	/* Pass force_dma false to require the DT to set the dma region */
+	ret = of_dma_configure(gmu->dev, node, false);
+	if (ret)
+		return ret;
+
+	/* Set the mask after the of_dma_configure() */
+	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(31));
+	if (ret)
+		return ret;
 
 	/* Fow now, don't do anything fancy until we get our feet under us */
 	gmu->idle_level = GMU_IDLE_STATE_ACTIVE;
@@ -1325,11 +1246,6 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
 	if (ret)
 		goto err_put_device;
 
-	/* Set up the IOMMU context bank */
-	ret = a6xx_gmu_memory_probe(gmu);
-	if (ret)
-		goto err_put_device;
-
 	/* Allocate memory for for the HFI queues */
 	gmu->hfi = a6xx_gmu_memory_alloc(gmu, SZ_16K);
 	if (IS_ERR(gmu->hfi))
@@ -1375,11 +1291,6 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
 err_memory:
 	a6xx_gmu_memory_free(gmu, gmu->hfi);
 
-	if (gmu->domain) {
-		iommu_detach_device(gmu->domain, gmu->dev);
-
-		iommu_domain_free(gmu->domain);
-	}
 	ret = -ENODEV;
 
 err_put_device:
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
index 2af91ed7ed0c..4af65a36d5ca 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
@@ -12,8 +12,7 @@
 struct a6xx_gmu_bo {
 	void *virt;
 	size_t size;
-	u64 iova;
-	struct page **pages;
+	dma_addr_t iova;
 };
 
 /*
@@ -49,9 +48,6 @@ struct a6xx_gmu {
 	int hfi_irq;
 	int gmu_irq;
 
-	struct iommu_domain *domain;
-	u64 uncached_iova_base;
-
 	struct device *gxpd;
 
 	int idle_level;
-- 
2.17.1