soc/intel/apollolake: Implement reset_prepare()

At first boot CSE spends long time preparing media for use. As result
it may not be able to deal with a CPU reset. Add reset_prepare()
callback that polls CSE readiness.

BUG=chrome-os-partner:55055
TEST=build with release version of fsp, reboot, observe polling for
CSE, then proper reboot happening

Change-Id: I639ef900b97132f1a7f269bb864d70009df9fdfe
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/15721
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/apollolake/reset.c

@@ -13,11 +13,47 @@
  * GNU General Public License for more details.
  */
 
+#include <console/console.h>
+#include <delay.h>
 #include <reset.h>
+#include <soc/heci.h>
 #include <soc/pm.h>
+#include <timer.h>
+
+#define CSE_WAIT_MAX_MS							1000
 
 void global_reset(void)
 {
 	global_reset_enable(1);
 	hard_reset();
 }
+
+void reset_prepare(void)
+{
+	struct stopwatch sw;
+
+	/*
+	 * If CSE state is something else than 'normal', it is probably in some
+	 * recovery state. In this case there is no point in  waiting for it to
+	 * get ready so we cross fingers and reset.
+	 */
+	if (!heci_cse_normal()) {
+		printk(BIOS_DEBUG, "CSE is not in normal state, resetting\n");
+		return;
+	}
+
+	/* Reset if CSE is ready */
+	if (heci_cse_done())
+		return;
+
+	printk(BIOS_SPEW, "CSE is not yet ready, waiting\n");
+	stopwatch_init_msecs_expire(&sw, CSE_WAIT_MAX_MS);
+	while (!heci_cse_done()) {
+		if (stopwatch_expired(&sw)) {
+			printk(BIOS_SPEW, "CSE timed out. Resetting\n");
+			return;
+		}
+		mdelay(1);
+	}
+	printk(BIOS_SPEW, "CSE took %lu ms\n", stopwatch_duration_msecs(&sw));
+}