tegra132: always bring up PLLD

The kernel does not correctly function without PLLD being enabled.
Additionally, PLLD can be the source for other clocks in the system.
Therefore, initialize PLLD to 300MHz unconditionally at BS_DEV_INIT
time in ramstage.

BUG=chrome-os-partner:33825
BRANCH=None
TEST=Built and booted ryu with display coming up both in dev mode as
     well as normal mode.

Change-Id: Ib2a60bb9aafc03dc23aa932a480184d87f677c65
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 4c49f964b55c3c33d03b95363277b262b679e740
Original-Change-Id: Ic5905e25051a042cea5010b8c6d61b1fb89a0a81
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/230774
Original-Reviewed-by: Tom Warren <twarren@nvidia.com>
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Tested-by: Sean Paul <seanpaul@chromium.org>
Reviewed-on: http://review.coreboot.org/9525
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/soc/nvidia/tegra132/soc.c

@@ -22,6 +22,7 @@
 #include <arch/cache.h>
 #include <arch/spintable.h>
 #include <cpu/cpu.h>
+#include <bootstate.h>
 #include <cbmem.h>
 #include <console/console.h>
 #include <device/device.h>
@@ -143,3 +144,20 @@ static const struct cpu_driver driver __cpu_driver = {
 	.ops      = &cpu_dev_ops,
 	.id_table = ids,
 };
+
+static void enable_plld(void *unused)
+{
+	/*
+	 * Configure a conservative 300MHz clock for PLLD. The kernel cannot
+	 * handle PLLD not being configured so enable PLLD unconditionally
+	 * with a default clock rate.
+	 */
+	clock_configure_plld(300 * MHz);
+}
+
+/*
+ * The PLLD being enabled is done at BS_DEV_INIT  time because mainboard_init()
+ * is the first thing called. This ensures PLLD is up and functional before
+ * anything that mainboard can do that implicitly relies on PLLD.
+ */
+BOOT_STATE_INIT_ENTRY(BS_DEV_INIT, BS_ON_ENTRY, enable_plld, NULL);