sh: Optimized cache handling for SH-4/SH-4A caches.

This reworks some of the SH-4 cache handling code to more easily
accomodate newer-style caches (particularly for the > direct-mapped
case), as well as optimizing some of the old code.

Signed-off-by: Richard Curnow <richard.curnow@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/arch/sh/kernel/cpu/init.c b/arch/sh/kernel/cpu/init.c
index 868e68b28880..731dd61419dd 100644
--- a/arch/sh/kernel/cpu/init.c
+++ b/arch/sh/kernel/cpu/init.c
@@ -4,6 +4,7 @@
  * CPU init code
  *
  * Copyright (C) 2002, 2003  Paul Mundt
+ * Copyright (C) 2003  Richard Curnow
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
@@ -51,7 +52,15 @@ static void __init cache_init(void)
         ccr = ctrl_inl(CCR);
 
         /*
-         * If the cache is already enabled .. flush it.
+         * At this point we don't know whether the cache is enabled or not - a
+         * bootloader may have enabled it.  There are at least 2 things that
+         * could be dirty in the cache at this point:
+         * 1. kernel command line set up by boot loader
+         * 2. spilled registers from the prolog of this function
+         * => before re-initialising the cache, we must do a purge of the whole
+         * cache out to memory for safety.  As long as nothing is spilled
+         * during the loop to lines that have already been done, this is safe.
+         * - RPC
          */
         if (ccr & CCR_CACHE_ENABLE) {
                 unsigned long ways, waysize, addrstart;
@@ -98,6 +107,8 @@ static void __init cache_init(void)
         /* Force EMODE if possible */
         if (cpu_data->dcache.ways > 1)
                 flags |= CCR_CACHE_EMODE;
+        else
+                flags &= ~CCR_CACHE_EMODE;
 #endif
 
 #ifdef CONFIG_SH_WRITETHROUGH
@@ -112,6 +123,9 @@ static void __init cache_init(void)
         /* Turn on OCRAM -- halve the OC */
         flags |= CCR_CACHE_ORA;
         cpu_data->dcache.sets >>= 1;
+
+        cpu_data->dcache.way_size = cpu_data->dcache.sets *
+                                    cpu_data->dcache.linesz;
 #endif
 
         ctrl_outl(flags, CCR);