1 files changed, 126 insertions, 0 deletions
diff --git a/common/fdt_fixup.c b/common/fdt_fixup.c
new file mode 100644
index 00000000..0ae0050c
--- /dev/null
+++ b/common/fdt_fixup.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/*
+ * Contains generic routines to fix up the device tree blob passed on to
+ * payloads like BL32 and BL33 (and further down the boot chain).
+ * This allows to easily add PSCI nodes, when the original DT does not have
+ * it or advertises another method.
+ */
+
+#include <string.h>
+
+#include <libfdt.h>
+
+#include <common/debug.h>
+#include <drivers/console.h>
+#include <lib/psci/psci.h>
+
+#include <common/fdt_fixup.h>
+
+static int append_psci_compatible(void *fdt, int offs, const char *str)
+{
+	return fdt_appendprop(fdt, offs, "compatible", str, strlen(str) + 1);
+}
+
+int dt_add_psci_node(void *fdt)
+{
+	int offs;
+
+	if (fdt_path_offset(fdt, "/psci") >= 0) {
+		WARN("PSCI Device Tree node already exists!\n");
+		return 0;
+	}
+
+	offs = fdt_path_offset(fdt, "/");
+	if (offs < 0)
+		return -1;
+	offs = fdt_add_subnode(fdt, offs, "psci");
+	if (offs < 0)
+		return -1;
+	if (append_psci_compatible(fdt, offs, "arm,psci-1.0"))
+		return -1;
+	if (append_psci_compatible(fdt, offs, "arm,psci-0.2"))
+		return -1;
+	if (append_psci_compatible(fdt, offs, "arm,psci"))
+		return -1;
+	if (fdt_setprop_string(fdt, offs, "method", "smc"))
+		return -1;
+	if (fdt_setprop_u32(fdt, offs, "cpu_suspend", PSCI_CPU_SUSPEND_AARCH64))
+		return -1;
+	if (fdt_setprop_u32(fdt, offs, "cpu_off", PSCI_CPU_OFF))
+		return -1;
+	if (fdt_setprop_u32(fdt, offs, "cpu_on", PSCI_CPU_ON_AARCH64))
+		return -1;
+	if (fdt_setprop_u32(fdt, offs, "sys_poweroff", PSCI_SYSTEM_OFF))
+		return -1;
+	if (fdt_setprop_u32(fdt, offs, "sys_reset", PSCI_SYSTEM_RESET))
+		return -1;
+	return 0;
+}
+
+/*
+ * Find the first subnode that has a "device_type" property with the value
+ * "cpu" and which's enable-method is not "psci" (yet).
+ * Returns 0 if no such subnode is found, so all have already been patched
+ * or none have to be patched in the first place.
+ * Returns 1 if *one* such subnode has been found and successfully changed
+ * to "psci".
+ * Returns -1 on error.
+ *
+ * Call in a loop until it returns 0. Recalculate the node offset after
+ * it has returned 1.
+ */
+static int dt_update_one_cpu_node(void *fdt, int offset)
+{
+	int offs;
+
+	/* Iterate over all subnodes to find those with device_type = "cpu". */
+	for (offs = fdt_first_subnode(fdt, offset); offs >= 0;
+	     offs = fdt_next_subnode(fdt, offs)) {
+		const char *prop;
+		int len;
+
+		prop = fdt_getprop(fdt, offs, "device_type", &len);
+		if (!prop)
+			continue;
+		if (memcmp(prop, "cpu", 4) != 0 || len != 4)
+			continue;
+
+		/* Ignore any nodes which already use "psci". */
+		prop = fdt_getprop(fdt, offs, "enable-method", &len);
+		if (prop && memcmp(prop, "psci", 5) == 0 && len == 5)
+			continue;
+
+		if (fdt_setprop_string(fdt, offs, "enable-method", "psci"))
+			return -1;
+		/*
+		 * Subnode found and patched.
+		 * Restart to accommodate potentially changed offsets.
+		 */
+		return 1;
+	}
+
+	if (offs == -FDT_ERR_NOTFOUND)
+		return 0;
+
+	return offs;
+}
+
+int dt_add_psci_cpu_enable_methods(void *fdt)
+{
+	int offs, ret;
+
+	do {
+		offs = fdt_path_offset(fdt, "/cpus");
+		if (offs < 0)
+			return offs;
+
+		ret = dt_update_one_cpu_node(fdt, offs);
+	} while (ret > 0);
+
+	return ret;
+}