drm/amdgpu: split amdgpu_device_access_vram() into two small parts

split amdgpu_device_access_vram()
1. amdgpu_device_mm_access(): using MM_INDEX/MM_DATA to access vram
2. amdgpu_device_aper_access(): using vram aperature to access vram (option)
Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1108,8 +1108,13 @@ void amdgpu_device_fini_sw(struct amdgpu_device *adev);
 
 int amdgpu_gpu_wait_for_idle(struct amdgpu_device *adev);
 
+void amdgpu_device_mm_access(struct amdgpu_device *adev, loff_t pos,
+			     void *buf, size_t size, bool write);
+size_t amdgpu_device_aper_access(struct amdgpu_device *adev, loff_t pos,
+				 void *buf, size_t size, bool write);
+
 void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
-			       uint32_t *buf, size_t size, bool write);
+			       void *buf, size_t size, bool write);
 uint32_t amdgpu_device_rreg(struct amdgpu_device *adev,
 			    uint32_t reg, uint32_t acc_flags);
 void amdgpu_device_wreg(struct amdgpu_device *adev,

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -287,7 +287,7 @@ bool amdgpu_device_supports_smart_shift(struct drm_device *dev)
  */
 
 /**
- * amdgpu_device_vram_access - read/write a buffer in vram
+ * amdgpu_device_mm_access - access vram by MM_INDEX/MM_DATA
  *
  * @adev: amdgpu_device pointer
  * @pos: offset of the buffer in vram
@@ -295,22 +295,65 @@ bool amdgpu_device_supports_smart_shift(struct drm_device *dev)
  * @size: read/write size, sizeof(@buf) must > @size
  * @write: true - write to vram, otherwise - read from vram
  */
-void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
-			       uint32_t *buf, size_t size, bool write)
+void amdgpu_device_mm_access(struct amdgpu_device *adev, loff_t pos,
+			     void *buf, size_t size, bool write)
 {
 	unsigned long flags;
-	uint32_t hi = ~0;
+	uint32_t hi = ~0, tmp = 0;
+	uint32_t *data = buf;
 	uint64_t last;
 	int idx;
 
 	if (!drm_dev_enter(&adev->ddev, &idx))
 		return;
 
+	BUG_ON(!IS_ALIGNED(pos, 4) || !IS_ALIGNED(size, 4));
+
+	spin_lock_irqsave(&adev->mmio_idx_lock, flags);
+	for (last = pos + size; pos < last; pos += 4) {
+		tmp = pos >> 31;
+
+		WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)pos) | 0x80000000);
+		if (tmp != hi) {
+			WREG32_NO_KIQ(mmMM_INDEX_HI, tmp);
+			hi = tmp;
+		}
+		if (write)
+			WREG32_NO_KIQ(mmMM_DATA, *data++);
+		else
+			*data++ = RREG32_NO_KIQ(mmMM_DATA);
+	}
+
+	spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
+	drm_dev_exit(idx);
+}
+
+/**
+ * amdgpu_device_vram_access - access vram by vram aperature
+ *
+ * @adev: amdgpu_device pointer
+ * @pos: offset of the buffer in vram
+ * @buf: virtual address of the buffer in system memory
+ * @size: read/write size, sizeof(@buf) must > @size
+ * @write: true - write to vram, otherwise - read from vram
+ *
+ * The return value means how many bytes have been transferred.
+ */
+size_t amdgpu_device_aper_access(struct amdgpu_device *adev, loff_t pos,
+				 void *buf, size_t size, bool write)
+{
 #ifdef CONFIG_64BIT
+	void __iomem *addr;
+	size_t count = 0;
+	uint64_t last;
+
+	if (!adev->mman.aper_base_kaddr)
+		return 0;
+
 	last = min(pos + size, adev->gmc.visible_vram_size);
 	if (last > pos) {
-		void __iomem *addr = adev->mman.aper_base_kaddr + pos;
-		size_t count = last - pos;
+		addr = adev->mman.aper_base_kaddr + pos;
+		count = last - pos;
 
 		if (write) {
 			memcpy_toio(addr, buf, count);
@@ -322,35 +365,37 @@ void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
 			memcpy_fromio(buf, addr, count);
 		}
 
-		if (count == size)
-			goto exit;
-
-		pos += count;
-		buf += count / 4;
-		size -= count;
 	}
+
+	return count;
+#else
+	return 0;
 #endif
+}
 
-	spin_lock_irqsave(&adev->mmio_idx_lock, flags);
-	for (last = pos + size; pos < last; pos += 4) {
-		uint32_t tmp = pos >> 31;
+/**
+ * amdgpu_device_vram_access - read/write a buffer in vram
+ *
+ * @adev: amdgpu_device pointer
+ * @pos: offset of the buffer in vram
+ * @buf: virtual address of the buffer in system memory
+ * @size: read/write size, sizeof(@buf) must > @size
+ * @write: true - write to vram, otherwise - read from vram
+ */
+void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
+			       void *buf, size_t size, bool write)
+{
+	size_t count;
 
-		WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)pos) | 0x80000000);
-		if (tmp != hi) {
-			WREG32_NO_KIQ(mmMM_INDEX_HI, tmp);
-			hi = tmp;
-		}
-		if (write)
-			WREG32_NO_KIQ(mmMM_DATA, *buf++);
-		else
-			*buf++ = RREG32_NO_KIQ(mmMM_DATA);
+	/* try to using vram apreature to access vram first */
+	count = amdgpu_device_aper_access(adev, pos, buf, size, write);
+	size -= count;
+	if (size) {
+		/* using MM to access rest vram */
+		pos += count;
+		buf += count;
+		amdgpu_device_mm_access(adev, pos, buf, size, write);
 	}
-	spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
-
-#ifdef CONFIG_64BIT
-exit:
-#endif
-	drm_dev_exit(idx);
 }
 
 /*