lib: utils/cache: Add fdt cmo helpers

Add the helpers to build up the cache hierarchy via FDT and provide some
cmo functions for the user who want to flush the entire cache.

Signed-off-by: Nick Hu <nick.hu@sifive.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251020-cache-upstream-v7-4-69a132447d8a@sifive.com
Signed-off-by: Anup Patel <anup@brainfault.org>

include/sbi_utils/cache/fdt_cmo_helper.h

@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 SiFive Inc.
+ */
+
+#ifndef __FDT_CMO_HELPER_H__
+#define __FDT_CMO_HELPER_H__
+
+#ifdef CONFIG_FDT_CACHE
+/**
+ * Flush the private first level cache of the current hart
+ *
+ * @return 0 on success, or a negative error code on failure
+ */
+int fdt_cmo_private_flc_flush_all(void);
+
+/**
+ * Flush the last level cache of the current hart
+ *
+ * @return 0 on success, or a negative error code on failure
+ */
+int fdt_cmo_llc_flush_all(void);
+
+/**
+ * Initialize the cache devices for each hart
+ *
+ * @param fdt devicetree blob
+ * @param cold_boot cold init or warm init
+ *
+ * @return 0 on success, or a negative error code on failure
+ */
+int fdt_cmo_init(bool cold_boot);
+
+#else
+
+static inline int fdt_cmo_init(bool cold_boot) { return 0; }
+
+#endif /* CONFIG_FDT_CACHE */
+#endif /* __FDT_CMO_HELPER_H__ */

lib/utils/cache/fdt_cmo_helper.c

@@ -0,0 +1,114 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2025 SiFive Inc.
+ */
+
+#include <libfdt.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_scratch.h>
+#include <sbi_utils/cache/fdt_cache.h>
+#include <sbi_utils/cache/fdt_cmo_helper.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+
+static unsigned long flc_offset;
+
+#define get_hart_flc(_s) \
+	sbi_scratch_read_type(_s, struct cache_device *, flc_offset)
+#define set_hart_flc(_s, _p) \
+	sbi_scratch_write_type(_s, struct cache_device *, flc_offset, _p)
+
+int fdt_cmo_private_flc_flush_all(void)
+{
+	struct cache_device *flc = get_hart_flc(sbi_scratch_thishart_ptr());
+
+	if (!flc || !flc->cpu_private)
+		return SBI_ENODEV;
+
+	return cache_flush_all(flc);
+}
+
+int fdt_cmo_llc_flush_all(void)
+{
+	struct cache_device *llc = get_hart_flc(sbi_scratch_thishart_ptr());
+
+	if (!llc)
+		return SBI_ENODEV;
+
+	while (llc->next)
+		llc = llc->next;
+
+	return cache_flush_all(llc);
+}
+
+static int fdt_cmo_cold_init(const void *fdt)
+{
+	struct sbi_scratch *scratch;
+	struct cache_device *dev;
+	int cpu_offset, cpus_offset, rc;
+	u32 hartid;
+
+	cpus_offset = fdt_path_offset(fdt, "/cpus");
+	if (cpus_offset < 0)
+		return SBI_EINVAL;
+
+	fdt_for_each_subnode(cpu_offset, fdt, cpus_offset) {
+		rc = fdt_parse_hart_id(fdt, cpu_offset, &hartid);
+		if (rc)
+			continue;
+
+		scratch = sbi_hartid_to_scratch(hartid);
+		if (!scratch)
+			continue;
+
+		rc = fdt_next_cache_get(fdt, cpu_offset, &dev);
+		if (rc && rc != SBI_ENOENT)
+			return rc;
+		if (rc == SBI_ENOENT)
+			dev = NULL;
+
+		set_hart_flc(scratch, dev);
+	}
+
+	return SBI_OK;
+}
+
+static int fdt_cmo_warm_init(void)
+{
+	struct cache_device *cur = get_hart_flc(sbi_scratch_thishart_ptr());
+	int rc;
+
+	while (cur) {
+		if (cur->ops && cur->ops->warm_init) {
+			rc = cur->ops->warm_init(cur);
+			if (rc)
+				return rc;
+		}
+
+		cur = cur->next;
+	}
+
+	return SBI_OK;
+}
+
+int fdt_cmo_init(bool cold_boot)
+{
+	const void *fdt = fdt_get_address();
+	int rc;
+
+	if (cold_boot) {
+		flc_offset = sbi_scratch_alloc_type_offset(struct cache_device *);
+		if (!flc_offset)
+			return SBI_ENOMEM;
+
+		rc = fdt_cmo_cold_init(fdt);
+		if (rc)
+			return rc;
+	}
+
+	rc = fdt_cmo_warm_init();
+	if (rc)
+		return rc;
+
+	return SBI_OK;
+}

lib/utils/cache/objects.mk

@@ -6,6 +6,7 @@
 
 libsbiutils-objs-$(CONFIG_FDT_CACHE) += cache/fdt_cache.o
 libsbiutils-objs-$(CONFIG_FDT_CACHE) += cache/fdt_cache_drivers.carray.o
+libsbiutils-objs-$(CONFIG_FDT_CACHE) += cache/fdt_cmo_helper.o
 
 carray-fdt_cache_drivers-$(CONFIG_FDT_CACHE_SIFIVE_CCACHE) += fdt_sifive_ccache
 libsbiutils-objs-$(CONFIG_FDT_CACHE_SIFIVE_CCACHE) += cache/fdt_sifive_ccache.o

platform/generic/platform.c

@@ -17,6 +17,7 @@
 #include <sbi/sbi_string.h>
 #include <sbi/sbi_system.h>
 #include <sbi/sbi_tlb.h>
+#include <sbi_utils/cache/fdt_cmo_helper.h>
 #include <sbi_utils/fdt/fdt_domain.h>
 #include <sbi_utils/fdt/fdt_driver.h>
 #include <sbi_utils/fdt/fdt_fixup.h>
@@ -230,7 +231,7 @@ int generic_early_init(bool cold_boot)
 		fdt_driver_init_all(fdt, fdt_early_drivers);
 	}
 
-	return 0;
+	return fdt_cmo_init(cold_boot);
 }
 
 int generic_final_init(bool cold_boot)