drm/nouveau/falcon: support for EMEM

On SEC, DMEM is unaccessible by the CPU when the falcon is running in LS
mode. This makes communication with the firmware using DMEM impossible.

For this purpose, a new kind of memory (EMEM) has been added. It works
similarly to DMEM, with the difference that its address space starts at
0x1000000. For this reason, it makes sense to treat it like a special
case of DMEM.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/engine/falcon.h

@@ -25,6 +25,7 @@ struct nvkm_falcon {
 	u8 version;
 	u8 secret;
 	bool debug;
+	bool has_emem;
 
 	struct nvkm_memory *core;
 	bool external;

drivers/gpu/drm/nouveau/nvkm/falcon/base.c

@@ -202,6 +202,7 @@ nvkm_falcon_ctor(const struct nvkm_falcon_func *func,
 		break;
 	case NVKM_ENGINE_SEC2:
 		debug_reg = 0x408;
+		falcon->has_emem = true;
 		break;
 	default:
 		nvkm_warn(subdev, "unsupported falcon %s!\n",

drivers/gpu/drm/nouveau/nvkm/falcon/v1.c

@@ -64,6 +64,33 @@ nvkm_falcon_v1_load_imem(struct nvkm_falcon *falcon, void *data, u32 start,
 		nvkm_falcon_wr32(falcon, 0x184 + (port * 16), 0);
 }
 
+static void
+nvkm_falcon_v1_load_emem(struct nvkm_falcon *falcon, void *data, u32 start,
+			 u32 size, u8 port)
+{
+	u8 rem = size % 4;
+	int i;
+
+	size -= rem;
+
+	nvkm_falcon_wr32(falcon, 0xac0 + (port * 8), start | (0x1 << 24));
+	for (i = 0; i < size / 4; i++)
+		nvkm_falcon_wr32(falcon, 0xac4 + (port * 8), ((u32 *)data)[i]);
+
+	/*
+	 * If size is not a multiple of 4, mask the last word to ensure garbage
+	 * does not get written
+	 */
+	if (rem) {
+		u32 extra = ((u32 *)data)[i];
+
+		nvkm_falcon_wr32(falcon, 0xac4 + (port * 8),
+				 extra & (BIT(rem * 8) - 1));
+	}
+}
+
+static const u32 EMEM_START_ADDR = 0x1000000;
+
 static void
 nvkm_falcon_v1_load_dmem(struct nvkm_falcon *falcon, void *data, u32 start,
 		      u32 size, u8 port)
@@ -71,6 +98,11 @@ nvkm_falcon_v1_load_dmem(struct nvkm_falcon *falcon, void *data, u32 start,
 	u8 rem = size % 4;
 	int i;
 
+	if (start >= EMEM_START_ADDR && falcon->has_emem)
+		return nvkm_falcon_v1_load_emem(falcon, data,
+						start - EMEM_START_ADDR, size,
+						port);
+
 	size -= rem;
 
 	nvkm_falcon_wr32(falcon, 0x1c0 + (port * 8), start | (0x1 << 24));
@@ -89,6 +121,33 @@ nvkm_falcon_v1_load_dmem(struct nvkm_falcon *falcon, void *data, u32 start,
 	}
 }
 
+static void
+nvkm_falcon_v1_read_emem(struct nvkm_falcon *falcon, u32 start, u32 size,
+			 u8 port, void *data)
+{
+	u8 rem = size % 4;
+	int i;
+
+	size -= rem;
+
+	nvkm_falcon_wr32(falcon, 0xac0 + (port * 8), start | (0x1 << 25));
+	for (i = 0; i < size / 4; i++)
+		((u32 *)data)[i] = nvkm_falcon_rd32(falcon, 0xac4 + (port * 8));
+
+	/*
+	 * If size is not a multiple of 4, mask the last word to ensure garbage
+	 * does not get read
+	 */
+	if (rem) {
+		u32 extra = nvkm_falcon_rd32(falcon, 0xac4 + (port * 8));
+
+		for (i = size; i < size + rem; i++) {
+			((u8 *)data)[i] = (u8)(extra & 0xff);
+			extra >>= 8;
+		}
+	}
+}
+
 static void
 nvkm_falcon_v1_read_dmem(struct nvkm_falcon *falcon, u32 start, u32 size,
 			 u8 port, void *data)
@@ -96,6 +155,10 @@ nvkm_falcon_v1_read_dmem(struct nvkm_falcon *falcon, u32 start, u32 size,
 	u8 rem = size % 4;
 	int i;
 
+	if (start >= EMEM_START_ADDR && falcon->has_emem)
+		return nvkm_falcon_v1_read_emem(falcon, start - EMEM_START_ADDR,
+						size, port, data);
+
 	size -= rem;
 
 	nvkm_falcon_wr32(falcon, 0x1c0 + (port * 8), start | (0x1 << 25));