hatch: Fix FPMCU pwr/rst gpio handling

1. No gpio control in bootblock
2. Disable power and assert reset in ramstage gpio
3. Power on and then deassert reset at the end of ramstage gpio
4. Disable power and assert reset when entering S5

On "reboot", the amount of time the power is disabled for is
equivalent to the amount of time between triggering #4 and wrapping
around to #3, which is about 400ms on Kohaku.

Since #2 forces power off for FPMCU, S3 resume will still
not work properly.

Additionally, we must ensure that GPP_A12 is reconfigured as an output
before going to any sleep state, since user space could have configured
it to use its native3 function.
See https://review.coreboot.org/c/coreboot/+/32111 for more detail.

The control signals have been validated on a Kohaku in
the following scenarios:
1. Cold startup
2. Issuing a "reboot" command
3. Issuing a "halt -p" and powering back on within 10 seconds
4. Issuing a "halt -p" and powering back on after 10 seconds
5. Entering and leaving S3 (does not work properly)
6. Entering and leaving S0iX

BRANCH=hatch
BUG=b/142751685
TEST=Verify all signals as mentioned above
TEST=reboot
     flash_fp_mcu /opt/google/biod/fw/dartmonkey_v2.0.2417-af88cc91a.bin
TEST=halt -p
     # power back on within 10 seconds
     flash_fp_mcu /opt/google/biod/fw/dartmonkey_v2.0.2417-af88cc91a.bin
TEST=halt -p
     # power back on after 10 seconds
     flash_fp_mcu /opt/google/biod/fw/dartmonkey_v2.0.2417-af88cc91a.bin

Change-Id: I2e3ff42715611d519677a4256bdd172ec98687f9
Signed-off-by: Craig Hesling <hesling@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37459
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/src/mainboard/google/hatch/variants/kohaku/ramstage.c b/src/mainboard/google/hatch/variants/kohaku/ramstage.c
new file mode 100644
index 0000000000..9b919fccd8
--- /dev/null
+++ b/src/mainboard/google/hatch/variants/kohaku/ramstage.c
@@ -0,0 +1,32 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2019 Google LLC
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <delay.h>
+#include <gpio.h>
+#include <baseboard/variants.h>
+#include <soc/gpio.h>
+
+void variant_ramstage_init(void)
+{
+	/*
+	 * Enable power to FPMCU, wait for power rail to stabilize,
+	 * and then deassert FPMCU reset.
+	 * Waiting for the power rail to stabilize can take a while,
+	 * a minimum of 400us on Kohaku.
+	 */
+	gpio_output(GPP_C11, 1);
+	mdelay(1);
+	gpio_output(GPP_A12, 1);
+}