drm/amdgpu: add a generic fb accessing helper function(v3)

add a generic helper function for accessing framebuffer via MMIO

Reviewed-by: Alex Deucher <[e-mail]>
Reviewed-by: Luben Tuikov <[e-mail]>
Signed-off-by: Tianci.Yin <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 void amdgpu_device_fini(struct amdgpu_device *adev);
 int amdgpu_gpu_wait_for_idle(struct amdgpu_device *adev);
 
+void amdgpu_device_vram_access(struct amdgpu_device *adev, loff_t pos,
+			       uint32_t *buf, size_t size, bool write);
 uint32_t amdgpu_mm_rreg(struct amdgpu_device *adev, uint32_t reg,
 			uint32_t acc_flags);
 void amdgpu_mm_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v,

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

···
 	return false;
 }
 
+/**
+ * VRAM access helper functions.
+ *
+ * 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,
+			       uint32_t *buf, size_t size, bool write)
+{
+	uint64_t last;
+	unsigned long flags;
+
+	last = size - 4;
+	for (last += pos; pos <= last; pos += 4) {
+		spin_lock_irqsave(&adev->mmio_idx_lock, flags);
+		WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)pos) | 0x80000000);
+		WREG32_NO_KIQ(mmMM_INDEX_HI, pos >> 31);
+		if (write)
+			WREG32_NO_KIQ(mmMM_DATA, *buf++);
+		else
+			*buf++ = RREG32_NO_KIQ(mmMM_DATA);
+		spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
+	}
+}
+
 /*
  * MMIO register access helper functions.
  */

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

···
 
 static int amdgpu_discovery_read_binary(struct amdgpu_device *adev, uint8_t *binary)
 {
-	uint32_t *p = (uint32_t *)binary;
 	uint64_t vram_size = (uint64_t)RREG32(mmRCC_CONFIG_MEMSIZE) << 20;
 	uint64_t pos = vram_size - DISCOVERY_TMR_SIZE;
-	unsigned long flags;
 
-	while (pos < vram_size) {
-		spin_lock_irqsave(&adev->mmio_idx_lock, flags);
-		WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)pos) | 0x80000000);
-		WREG32_NO_KIQ(mmMM_INDEX_HI, pos >> 31);
-		*p++ = RREG32_NO_KIQ(mmMM_DATA);
-		spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
-		pos += 4;
-	}
-
+	amdgpu_device_vram_access(adev, pos, (uint32_t *)binary, DISCOVERY_TMR_SIZE, false);
 	return 0;
 }