[PATCH] generic: fu740: add workaround for CIP-1200 errata

[Heinrich Schuchardt]

From: David Abdurachmanov <david.abdurachmanov at sifive.com>

Instruction TLB can fail to respect a non-global SFENCE thus we need to
flush the TLB using SFENCE.VMA x0, x0

See full description of CIP-1200 in Errata_FU740-C000_20210205 from
https://www.sifive.com/boards/hifive-unmatched

Signed-off-by: David Abdurachmanov <david.abdurachmanov at sifive.com>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 platform/generic/objects.mk     |  1 +
 platform/generic/platform.c     |  2 ++
 platform/generic/sifive_fu740.c | 36 +++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)
 create mode 100644 platform/generic/sifive_fu740.c

diff --git a/platform/generic/objects.mk b/platform/generic/objects.mk
index d6c8a42..cb15a18 100644
--- a/platform/generic/objects.mk
+++ b/platform/generic/objects.mk
@@ -9,3 +9,4 @@

 platform-objs-y += platform.o
 platform-objs-y += sifive_fu540.o
+platform-objs-y += sifive_fu740.o
diff --git a/platform/generic/platform.c b/platform/generic/platform.c
index 8c1e06f..2d5e930 100644
--- a/platform/generic/platform.c
+++ b/platform/generic/platform.c
@@ -23,9 +23,11 @@
 #include <sbi_utils/reset/fdt_reset.h>

 extern const struct platform_override sifive_fu540;
+extern const struct platform_override sifive_fu740;

 static const struct platform_override *special_platforms[] = {
 	&sifive_fu540,
+	&sifive_fu740,
 };

 static const struct platform_override *generic_plat = NULL;
diff --git a/platform/generic/sifive_fu740.c b/platform/generic/sifive_fu740.c
new file mode 100644
index 0000000..c8325d3
--- /dev/null
+++ b/platform/generic/sifive_fu740.c
@@ -0,0 +1,36 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 SiFive
+ *
+ * Authors:
+ *   David Abdurachmanov <david.abdurachmanov at sifive.com>
+ */
+
+#include <platform_override.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/fdt/fdt_fixup.h>
+
+static u64 sifive_fu740_tlbr_flush_limit(const struct fdt_match *match)
+{
+	/*
+	 * Needed to address CIP-1200 errata on SiFive FU740
+	 * Title: Instruction TLB can fail to respect a non-global SFENCE
+	 * Workaround: Flush the TLB using SFENCE.VMA x0, x0
+	 * See Errata_FU740-C000_20210205 from
+	 * https://www.sifive.com/boards/hifive-unmatched
+	 */
+	return 0;
+}
+
+static const struct fdt_match sifive_fu740_match[] = {
+	{ .compatible = "sifive,fu740" },
+	{ .compatible = "sifive,fu740-c000" },
+	{ .compatible = "sifive,hifive-unmatched-a00" },
+	{ },
+};
+
+const struct platform_override sifive_fu740 = {
+	.match_table = sifive_fu740_match,
+	.tlbr_flush_limit = sifive_fu740_tlbr_flush_limit,
+};
--
2.29.2