Remove cache maintenance

For models, we assume that out-of-reset caches are invalid and no cache
maintenance is required.

We added cache maintenance to the boot-wrapper in commit:

  28ec269a22c8dc14 ("Add code to clean and invalidate caches")

... because the boot-wrapper would transiently use cacheable mappings,
and could allocate into caches. As we were using Set/Way operations, we
were on somewhat shaky ground (e.g. due to system-level caches, or
dirty line migration). Further, we never took FEAT_CCIDX into account,
and so would not necessarily invalidate all potential levels of cache

However, since commit:

  0bb7b2545582accf ("Remove MMU identity map setup")

... we no longer enable the MMU within the boot-wrapper, and so no
longer have any reason to perform cache maintenance.

This patch removes the redundant and incomplete cache maintenance.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>

3 files changed, 1 insertions, 62 deletions

diff --git a/Makefile.am b/Makefile.am
index 2c2fd25..8ffb2d6 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -123,7 +123,7 @@ CFLAGS		+= -Wall -fomit-frame-pointer
 CFLAGS		+= -ffunction-sections -fdata-sections
 LDFLAGS		+= --gc-sections
 
-OFILES		+= boot_common.o bakery_lock.o platform.o $(GIC) cache.o lib.o
+OFILES		+= boot_common.o bakery_lock.o platform.o $(GIC) lib.o
 OFILES		+= $(addprefix $(ARCH_SRC),boot.o stack.o $(BOOTMETHOD) utils.o)
 
 # Don't lookup all prerequisites in $(top_srcdir), only the source files. When
diff --git a/boot_common.c b/boot_common.c
index e7b8e1d..d48b7e1 100644
--- a/boot_common.c
+++ b/boot_common.c
@@ -13,7 +13,6 @@ extern unsigned long entrypoint;
 extern unsigned long dtb;
 
 void init_platform(void);
-void flush_caches(void);
 
 void __noreturn jump_kernel(unsigned long address,
 			    unsigned long a0,
@@ -62,8 +61,6 @@ void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry)
 void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid)
 {
-	flush_caches();
-
 	if (cpu == 0) {
 		init_platform();
 
diff --git a/cache.c b/cache.c
deleted file mode 100644
index 9d71248..0000000
--- a/cache.c
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * cache.c - simple cache clean+invalidate code
- *
- * Copyright (C) 2015 ARM Limited. All rights reserved.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE.txt file.
- */
-
-#include <cpu.h>
-
-void flush_caches(void)
-{
-	unsigned int level;
-	uint32_t clidr = read_clidr();
-	unsigned int max_level = (clidr >> 24) & 0x7;
-
-	uint32_t ccsidr;
-
-	if (max_level == 0)
-		return;
-
-	for (level = 0; level < max_level; level++) {
-		uint32_t cache_type = (clidr >> (level * 3)) & 0x7;
-		unsigned int line_size, num_ways, num_sets, way_shift;
-		unsigned int way, set;
-
-		if (cache_type == 1)
-			/* No dcache at this level */
-			continue;
-
-		write_csselr(level << 1);
-		isb();
-		ccsidr = read_ccsidr();
-
-		line_size = (ccsidr & 0x7) + 4; /* log2 line size */
-		num_ways = ((ccsidr >> 3) & 0x3ff) + 1;
-		num_sets = ((ccsidr >> 13) & 0x7fff) + 1;
-
-		way_shift = clz(num_ways - 1);
-		for (way = 0; way < num_ways; way++) {
-			for (set = 0; set < num_sets; set++) {
-				uint32_t command = level << 1;
-				command |= way << way_shift;
-				command |= set << line_size;
-
-				dccisw(command);
-				dsb(sy);
-			}
-		}
-
-		dsb(sy);
-	}
-	dsb(sy);
-	iciallu();
-	dsb(sy);
-	isb();
-}