arch: Unify basic cache clearing API

Caching is a very architecture-specific thing, but most architectures
have a cache in general. Therefore it can be useful to have a generic
architecture-independent API to perform simple cache management tasks
from common code.

We have already standardized on the dcache_clean/invalidate naming
scheme that originally comes from ARM in libpayload, so let's just do
the same for coreboot. Unlike libpayload, there are other things than
just DMA coherency we may want to achieve with those functions, so
actually implement them for real even on architectures with
cache-snooping DMA like x86. (In the future, we may find applications
like this in libpayload as well and should probably rethink the API
there... maybe move the current functionality to a separate
dma_map/unmap API instead. But that's beyond scope of this patch.)

Change-Id: I2c1723a287f76cd4118ef38a445339840601aeea
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/19788
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/src/arch/riscv/include/arch/cache.h b/src/arch/riscv/include/arch/cache.h
new file mode 100644
index 0000000000..ba7c33da47
--- /dev/null
+++ b/src/arch/riscv/include/arch/cache.h
@@ -0,0 +1,40 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2017 Google Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ */
+
+#ifndef ARCH_CACHE_H
+#define ARCH_CACHE_H
+
+/* TODO: implement these API stubs once caching is available on RISC-V */
+static inline void cache_sync_instructions(void) {}
+static inline void dcache_clean_all(void) {}
+static inline void dcache_invalidate_all(void) {}
+static inline void dcache_clean_invalidate_all(void) {}
+
+#endif /* ARCH_CACHE_H */