command/cmd_cache.c: Add optional flush arguments

It might be desirable to have the ability to flush icache/dcache
within u-boot, this patch gives each arch the ability to provide
a flush_dcache/flush_icache function to let u-boot flush caches
from the prompt

Signed-off-by: Matthew McClintock <msm@freescale.com>

common/cmd_cache.c

@@ -26,18 +26,27 @@
  */
 #include <common.h>
 #include <command.h>
+#include <linux/compiler.h>
 
-static int on_off (const char *);
+static int parse_argv(const char *);
+
+void __weak flush_icache(void)
+{
+	/* please define arch specific flush_icache */
+	puts("No arch specific flush_icache available!\n");
+}
 
 int do_icache ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	switch (argc) {
 	case 2:			/* on / off	*/
-		switch (on_off(argv[1])) {
+		switch (parse_argv(argv[1])) {
 		case 0:	icache_disable();
 			break;
 		case 1:	icache_enable ();
 			break;
+		case 2: flush_icache();
+			break;
 		}
 		/* FALL TROUGH */
 	case 1:			/* get status */
@@ -50,15 +59,23 @@ int do_icache ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	return 0;
 }
 
+void __weak flush_dcache(void)
+{
+	puts("No arch specific flush_dcache available!\n");
+	/* please define arch specific flush_dcache */
+}
+
 int do_dcache ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	switch (argc) {
 	case 2:			/* on / off	*/
-		switch (on_off(argv[1])) {
+		switch (parse_argv(argv[1])) {
 		case 0:	dcache_disable();
 			break;
 		case 1:	dcache_enable ();
 			break;
+		case 2: flush_dcache();
+			break;
 		}
 		/* FALL TROUGH */
 	case 1:			/* get status */
@@ -72,9 +89,11 @@ int do_dcache ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 
 }
 
-static int on_off (const char *s)
+static int parse_argv(const char *s)
 {
-	if (strcmp(s, "on") == 0) {
+	if (strcmp(s, "flush") == 0) {
+		return (2);
+	} else if (strcmp(s, "on") == 0) {
 		return (1);
 	} else if (strcmp(s, "off") == 0) {
 		return (0);
@@ -86,13 +105,13 @@ static int on_off (const char *s)
 U_BOOT_CMD(
 	icache,   2,   1,     do_icache,
 	"enable or disable instruction cache",
-	"[on, off]\n"
-	"    - enable or disable instruction cache"
+	"[on, off, flush]\n"
+	"    - enable, disable, or flush instruction cache"
 );
 
 U_BOOT_CMD(
 	dcache,   2,   1,     do_dcache,
 	"enable or disable data cache",
-	"[on, off]\n"
-	"    - enable or disable data (writethrough) cache"
+	"[on, off, flush]\n"
+	"    - enable, disable, or flush data (writethrough) cache"
 );