[U-Boot] [PATCH v2 2/7] riscv: move the AX25-specific implementation of flush_dcache_all

[Lukas Auer]

The fence instruction is used to enforce device I/O and memory ordering
constraints in RISC-V. It can not be relied on to directly affect the
data cache on every CPU.
Andes' AX25 does not have a coherence agent. Its fence instruction
flushes the data cache and is used to keep data in the system coherent.
The implementation of flush_dcache_all in lib/cache.c is therefore
specific to the AX25. Move it into the AX25-specific cache.c in
cpu/ax25/.

This also adds a missing new line between flush_dcache_all and
flush_dcache_range in lib/cache.c.

Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
---

Changes in v2:
- Replace patch "riscv: remove invalid dcache flush implementation" with
new patch "riscv: move the AX25-specific implementation of
flush_dcache_all"

 arch/riscv/cpu/ax25/cache.c | 22 ++++++++++++++++++++++
 arch/riscv/lib/cache.c      | 10 ++++------
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/cpu/ax25/cache.c b/arch/riscv/cpu/ax25/cache.c
index 8d6ae170b8..228fc55f56 100644
--- a/arch/riscv/cpu/ax25/cache.c
+++ b/arch/riscv/cpu/ax25/cache.c
@@ -6,6 +6,28 @@
 
 #include <common.h>
 
+void flush_dcache_all(void)
+{
+	/*
+	 * Andes' AX25 does not have a coherence agent. U-Boot must use data
+	 * cache flush and invalidate functions to keep data in the system
+	 * coherent.
+	 * The implementation of the fence instruction in the AX25 flushes the
+	 * data cache and is used for this purpose.
+	 */
+	asm volatile ("fence" ::: "memory");
+}
+
+void flush_dcache_range(unsigned long start, unsigned long end)
+{
+	flush_dcache_all();
+}
+
+void invalidate_dcache_range(unsigned long start, unsigned long end)
+{
+	flush_dcache_all();
+}
+
 void icache_enable(void)
 {
 #ifndef CONFIG_SYS_ICACHE_OFF
diff --git a/arch/riscv/lib/cache.c b/arch/riscv/lib/cache.c
index ae5c60716f..78b19da2c5 100644
--- a/arch/riscv/lib/cache.c
+++ b/arch/riscv/lib/cache.c
@@ -11,13 +11,12 @@ void invalidate_icache_all(void)
 	asm volatile ("fence.i" ::: "memory");
 }
 
-void flush_dcache_all(void)
+__weak void flush_dcache_all(void)
 {
-	asm volatile ("fence" :::"memory");
 }
-void flush_dcache_range(unsigned long start, unsigned long end)
+
+__weak void flush_dcache_range(unsigned long start, unsigned long end)
 {
-	flush_dcache_all();
 }
 
 void invalidate_icache_range(unsigned long start, unsigned long end)
@@ -29,9 +28,8 @@ void invalidate_icache_range(unsigned long start, unsigned long end)
 	invalidate_icache_all();
 }
 
-void invalidate_dcache_range(unsigned long start, unsigned long end)
+__weak void invalidate_dcache_range(unsigned long start, unsigned long end)
 {
-	flush_dcache_all();
 }
 
 void cache_flush(void)
-- 
2.20.1