lib: device_tree: Add device_tree libraryHEADmastermain

Add device_tree library that adds a few wrappers on top of libfdt to
help read values out of properties that can have mutiple rows of
variable sized values.

Bug: 297275002
Change-Id: Iac0f757f82d0b6f8e8c6b29cb41efd61ffeca589

3 files changed, 199 insertions, 0 deletions

diff --git a/lib/device_tree/include/lib/device_tree/libfdt_helpers.h b/lib/device_tree/include/lib/device_tree/libfdt_helpers.h
new file mode 100644
index 00000000..22acce77
--- /dev/null
+++ b/lib/device_tree/include/lib/device_tree/libfdt_helpers.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2024 LK Trusty Authors. All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#include <libfdt.h>
+#include <lk/types.h>
+
+status_t fdt_helper_read_cells32(const fdt32_t* fdt_prop,
+                                 int fdt_prop_len,
+                                 int row_index,
+                                 int before_cells,
+                                 int cells,
+                                 int after_cells,
+                                 uint64_t* valp);
+
+status_t fdt_helper_get_reg(const void* fdt,
+                            int nodeoffset,
+                            int reg_index,
+                            paddr_t* addrp,
+                            size_t* sizep);
diff --git a/lib/device_tree/libfdt_helpers.c b/lib/device_tree/libfdt_helpers.c
new file mode 100644
index 00000000..dc6eb17f
--- /dev/null
+++ b/lib/device_tree/libfdt_helpers.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2024 LK Trusty Authors. All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <lib/device_tree/libfdt_helpers.h>
+#include "err.h"
+#include "lk/types.h"
+
+/**
+ * fdt_helper_read_cells32 - Read and convert cells.
+ * @fdt_prop:       Pointer to property to read from.
+ * @fdt_prop_len:   Length of @fdt_prop in bytes (not count of 32 bit values).
+ * @row_index:      Row to read from.
+ * @before_cells:   Number of cells to ignore in each row before the cells we
+ *                  read and convert.
+ * @cells:          Number of cells to read and convert to cpu endian.
+ * @after_cells:    Number of cells to ignore in each row after the cell we read
+ *                  and convert.
+ * @valp:           Pointer to store converted value in.
+ *
+ * Return:
+ * * %0:                Success.
+ * * %ERR_OUT_OF_RANGE: @fdt_prop_len is too small for the requested read.
+ * * %ERR_TOO_BIG:      value does not fit in uint64_t (only possible if
+ *                      cells > 2).
+ */
+status_t fdt_helper_read_cells32(const fdt32_t* fdt_prop,
+                                 int fdt_prop_len,
+                                 int row_index,
+                                 int before_cells,
+                                 int cells,
+                                 int after_cells,
+                                 uint64_t* valp) {
+    uint64_t ret = 0;
+    int cell_index =
+            row_index * (before_cells + cells + after_cells) + before_cells;
+    if (cell_index + cells > (fdt_prop_len / (int)sizeof(fdt32_t))) {
+        return ERR_OUT_OF_RANGE;
+    }
+    while (cells-- > 0) {
+        if (ret > UINT32_MAX) {
+            return ERR_TOO_BIG;
+        }
+        ret = ret << 32 | fdt32_to_cpu(fdt_prop[cell_index++]);
+    }
+    *valp = ret;
+    return 0;
+}
+
+/**
+ * fdt_helper_get_reg - Get address and size from reg property of a node.
+ * @fdt:            Pointer to device tree.
+ * @nodeoffset:     Node to use.
+ * @reg_index:      Row to read from.
+ *
+ * Return:
+ * * %0:                Success.
+ * * %ERR_NOT_FOUND:    Node does not have a reg property.
+ * * %ERR_OUT_OF_RANGE: reg property is too small for the requested read.
+ * * %ERR_TOO_BIG:      reg value does not fit in paddr_t or size_t.
+ */
+status_t fdt_helper_get_reg(const void* fdt,
+                            int nodeoffset,
+                            int reg_index,
+                            paddr_t* addrp,
+                            size_t* sizep) {
+    status_t ret = 0;
+    int parent_offset = fdt_parent_offset(fdt, nodeoffset);
+    int address_cells = fdt_address_cells(fdt, parent_offset);
+    int size_cells = fdt_size_cells(fdt, parent_offset);
+    int reg_prop_len;
+    const fdt32_t* reg_prop =
+            fdt_getprop(fdt, nodeoffset, "reg", &reg_prop_len);
+    if (!reg_prop) {
+        return ERR_NOT_FOUND;
+    }
+    if (addrp) {
+        uint64_t addr64;
+        ret = fdt_helper_read_cells32(reg_prop, reg_prop_len, reg_index, 0,
+                                      address_cells, size_cells, &addr64);
+        if (ret) {
+            return ret;
+        }
+        if (addr64 > PADDR_MAX) {
+            return ERR_TOO_BIG;
+        }
+        *addrp = addr64;
+    }
+    if (sizep) {
+        uint64_t size64;
+        ret = fdt_helper_read_cells32(reg_prop, reg_prop_len, reg_index,
+                                      address_cells, size_cells, 0, &size64);
+        if (ret) {
+            return ret;
+        }
+        if (size64 > SIZE_MAX) {
+            return ERR_TOO_BIG;
+        }
+        *sizep = size64;
+    }
+    return 0;
+}
diff --git a/lib/device_tree/rules.mk b/lib/device_tree/rules.mk
new file mode 100644
index 00000000..903de373
--- /dev/null
+++ b/lib/device_tree/rules.mk
@@ -0,0 +1,37 @@
+#
+# Copyright (c) 2024 LK Trusty Authors. All Rights Reserved.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files
+# (the "Software"), to deal in the Software without restriction,
+# including without limitation the rights to use, copy, modify, merge,
+# publish, distribute, sublicense, and/or sell copies of the Software,
+# and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+
+LOCAL_DIR := $(GET_LOCAL_DIR)
+
+MODULE := $(LOCAL_DIR)
+
+MODULE_LIBRARY_DEPS += \
+	external/dtc/libfdt \
+
+MODULE_EXPORT_INCLUDES += \
+	$(LOCAL_DIR)/include \
+
+MODULE_SRCS += \
+	$(LOCAL_DIR)/libfdt_helpers.c \
+
+include make/library.mk