soc/intel/apollolake: Flush L1D to L2 only if loaded segment is in CAR

In program_segment_loaded, flush L1D to L2 only if the address of the
loaded segment lies in the CAR region. Add an assert to ensure that
the loaded segment does not cross CAR boundaries.

Change-Id: Ie43e99299ed82f01518c8a1c1fd2bc64747d0c7b
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/14449
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/soc/intel/apollolake/car.c

@@ -16,6 +16,7 @@
  */
 
 #include <arch/cpu.h>
+#include <assert.h>
 #include <program_loading.h>
 #include <soc/cpu.h>
 
@@ -31,11 +32,27 @@ static void flush_l1d_to_l2(void)
 	wrmsr(MSR_POWER_MISC, msr);
 }
 
+static inline int is_car_addr(uintptr_t addr)
+{
+	return ((addr >= CONFIG_DCACHE_RAM_BASE) &&
+		(addr < (CONFIG_DCACHE_RAM_BASE + CONFIG_DCACHE_RAM_SIZE)));
+}
+
 void platform_segment_loaded(uintptr_t start, size_t size, int flags)
 {
-	/* TODO: filter on address to see if L1D flushing required. */
+	/* Bail out if this is not the final segment. */
+	if (!(flags & SEG_FINAL))
+		return;
 
-	/* Flush L1D cache to L2 on final segment loaded */
+	char start_car_check = is_car_addr(start);
-	if (flags & SEG_FINAL)
+	char end_car_check = is_car_addr(start + size - 1);
-		flush_l1d_to_l2();
+
+	/* Bail out if loaded program segment does not lie in CAR region. */
+	if (!start_car_check && !end_car_check)
+		return;
+
+	/* Loaded program segment should lie entirely within CAR region. */
+	assert (start_car_check && end_car_check);
+
+	flush_l1d_to_l2();
 }