[U-Boot] [PATCH v3 13/13] p2771-0000: Add support for framebuffer carveouts

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

If early firmware initialized the display hardware and the display
controllers are scanning out a framebuffer (e.g. a splash screen), make
sure to pass information about the memory location of that framebuffer
to the kernel before booting to avoid the kernel from using that memory
for the buddy allocator.

This same mechanism can also be used in the kernel to set up early SMMU
mappings and avoid SMMU faults caused by the display controller reading
from memory for which it has no mapping.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 board/nvidia/p2771-0000/p2771-0000.c | 66 ++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 4 deletions(-)

diff --git a/board/nvidia/p2771-0000/p2771-0000.c b/board/nvidia/p2771-0000/p2771-0000.c
index fe22067f6571..d294c7ae0136 100644
--- a/board/nvidia/p2771-0000/p2771-0000.c
+++ b/board/nvidia/p2771-0000/p2771-0000.c
@@ -5,6 +5,7 @@
 
 #include <common.h>
 #include <environment.h>
+#include <fdtdec.h>
 #include <i2c.h>
 #include <linux/libfdt.h>
 #include <asm/arch-tegra/cboot.h>
@@ -56,7 +57,7 @@ int tegra_pcie_board_init(void)
 }
 #endif
 
-int ft_board_setup(void *fdt, bd_t *bd)
+static void ft_mac_address_setup(void *fdt)
 {
 	const void *cboot_fdt = (const void *)cboot_boot_x0;
 	uint8_t mac[ETH_ALEN], local_mac[ETH_ALEN];
@@ -69,13 +70,15 @@ int ft_board_setup(void *fdt, bd_t *bd)
 
 	path = fdt_get_alias(fdt, "ethernet");
 	if (!path)
-		return 0;
+		return;
 
 	debug("ethernet alias found: %s\n", path);
 
 	offset = fdt_path_offset(fdt, path);
-	if (offset < 0)
-		return 0;
+	if (offset < 0) {
+		printf("ethernet alias points to absent node %s\n", path);
+		return;
+	}
 
 	if (is_valid_ethaddr(local_mac)) {
 		err = fdt_setprop(fdt, offset, "local-mac-address", local_mac,
@@ -92,6 +95,61 @@ int ft_board_setup(void *fdt, bd_t *bd)
 				debug("MAC address set: %pM\n", mac);
 		}
 	}
+}
+
+static int ft_copy_carveout(void *dst, const void *src, const char *node)
+{
+	struct fdt_memory fb;
+	int err;
+
+	err = fdtdec_get_carveout(src, node, "memory-region", 0, &fb);
+	if (err < 0) {
+		if (err != -FDT_ERR_NOTFOUND)
+			printf("failed to get carveout for %s: %d\n", node,
+			       err);
+
+		return err;
+	}
+
+	err = fdtdec_set_carveout(dst, node, "memory-region", 0, "framebuffer",
+				  &fb);
+	if (err < 0) {
+		printf("failed to set carveout for %s: %d\n", node, err);
+		return err;
+	}
+
+	return 0;
+}
+
+static void ft_carveout_setup(void *fdt)
+{
+	const void *cboot_fdt = (const void *)cboot_boot_x0;
+	static const char * const nodes[] = {
+		"/host1x at 13e00000/display-hub at 15200000/display at 15200000",
+		"/host1x at 13e00000/display-hub at 15200000/display at 15210000",
+		"/host1x at 13e00000/display-hub at 15200000/display@15220000",
+	};
+	unsigned int i;
+	int err;
+
+	for (i = 0; i < ARRAY_SIZE(nodes); i++) {
+		printf("copying carveout for %s...\n", nodes[i]);
+
+		err = ft_copy_carveout(fdt, cboot_fdt, nodes[i]);
+		if (err < 0) {
+			if (err != -FDT_ERR_NOTFOUND)
+				printf("failed to copy carveout for %s: %d\n",
+				       nodes[i], err);
+
+			continue;
+		}
+	}
+}
+
+int ft_board_setup(void *fdt, bd_t *bd)
+{
+	ft_mac_address_setup(fdt);
+	ft_carveout_setup(fdt);
 
 	return 0;
 }
-- 
2.21.0