pd: Store PD active state in battery-backed memory

Our previous idea to cut Rd for many reset cases cannot work if cr50
consistently resets the EC by asserting the reset pin shortly after
power-on. Therefore, make a decision based upon whether battery-backed
memory indicates we previously negotiated a PD power contract as a sink.
If we previously did not negotiate a contract, or if power was removed
from the device (causing battery-backed memory to wipe) then we can
assume that we don't have an active power contract.

BUG=chrome-os-partner:62952
BRANCH=reef
TEST=On reef, run "cutoff" on the console, reattach AC, and verify
device successfully wakes. Also verify Rp is dropped on console 'reboot'
and F3 + power from RW.

Change-Id: Ie300b9589cac6be7a69b77678bea6b1b6b25578c
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/443356
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 20 insertions, 8 deletions

diff --git a/chip/mec1322/system.c b/chip/mec1322/system.c
index 54ff2f45c8..4b2738e969 100644
--- a/chip/mec1322/system.c
+++ b/chip/mec1322/system.c
@@ -24,6 +24,8 @@
 enum hibdata_index {
 	HIBDATA_INDEX_SCRATCHPAD = 0,    /* General-purpose scratchpad */
 	HIBDATA_INDEX_SAVED_RESET_FLAGS, /* Saved reset flags */
+	HIBDATA_INDEX_PD0,               /* USB-PD0 saved port state */
+	HIBDATA_INDEX_PD1,               /* USB-PD1 saved port state */
 };
 
 static void check_reset_cause(void)
@@ -166,14 +168,26 @@ const char *system_get_chip_revision(void)
 	return buf;
 }
 
-int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
+static int bbram_idx_lookup(enum system_bbram_idx idx)
 {
-	enum hibdata_index hibdata;
-
 	switch (idx) {
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+	case SYSTEM_BBRAM_IDX_PD0:
+		return HIBDATA_INDEX_PD0;
+	case SYSTEM_BBRAM_IDX_PD1:
+		return HIBDATA_INDEX_PD1;
+#endif
 	default:
-		return EC_ERROR_UNIMPLEMENTED;
+		return -1;
 	}
+}
+
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
+{
+	int hibdata = bbram_idx_lookup(idx);
+
+	if (hibdata < 0)
+		return EC_ERROR_UNIMPLEMENTED;
 
 	*value = MEC1322_VBAT_RAM(hibdata);
 	return EC_SUCCESS;
@@ -181,12 +195,10 @@ int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 
 int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
-	enum hibdata_index hibdata;
+	int hibdata = bbram_idx_lookup(idx);
 
-	switch (idx) {
-	default:
+	if (hibdata < 0)
 		return EC_ERROR_UNIMPLEMENTED;
-	}
 
 	MEC1322_VBAT_RAM(hibdata) = value;
 	return EC_SUCCESS;