firmware: qcom_scm-32: replace open-coded call to __cpuc_flush_dcache_area()

Rathe rthan directly accessing architecture internal functions, provide
an "method"-centric wrapper for qcom_scm-32 to do what's necessary to
ensure that the secure monitor can see the data.  This is called
"secure_flush_area" and ensures that the specified memory area is
coherent across the secure boundary.
Acked-by: Andy Gross <agross@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/cacheflush.h

@@ -502,4 +502,21 @@ static inline void set_kernel_text_ro(void) { }
 void flush_uprobe_xol_access(struct page *page, unsigned long uaddr,
 			     void *kaddr, unsigned long len);
 
+/**
+ * secure_flush_area - ensure coherency across the secure boundary
+ * @addr: virtual address
+ * @size: size of region
+ *
+ * Ensure that the specified area of memory is coherent across the secure
+ * boundary from the non-secure side.  This is used when calling secure
+ * firmware where the secure firmware does not ensure coherency.
+ */
+static inline void secure_flush_area(const void *addr, size_t size)
+{
+	phys_addr_t phys = __pa(addr);
+
+	__cpuc_flush_dcache_area((void *)addr, size);
+	outer_flush_range(phys, phys + size);
+}
+
 #endif

drivers/firmware/qcom_scm-32.c

@@ -24,7 +24,6 @@
 #include <linux/err.h>
 #include <linux/qcom_scm.h>
 
-#include <asm/outercache.h>
 #include <asm/cacheflush.h>
 
 #include "qcom_scm.h"
@@ -219,8 +218,7 @@ static int __qcom_scm_call(const struct qcom_scm_command *cmd)
 	 * Flush the command buffer so that the secure world sees
 	 * the correct data.
 	 */
-	__cpuc_flush_dcache_area((void *)cmd, cmd->len);
-	outer_flush_range(cmd_addr, cmd_addr + cmd->len);
+	secure_flush_area(cmd, cmd->len);
 
 	ret = smc(cmd_addr);
 	if (ret < 0)