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>
Reviewed-on: https://chromium-review.googlesource.com/446873

8 files changed, 85 insertions, 14 deletions

diff --git a/chip/it83xx/registers.h b/chip/it83xx/registers.h
index a90b5b72f2..e47c40e97c 100644
--- a/chip/it83xx/registers.h
+++ b/chip/it83xx/registers.h
@@ -1075,7 +1075,11 @@ enum bram_indices {
 	BRAM_IDX_RESET_FLAGS2 = 2,
 	BRAM_IDX_RESET_FLAGS3 = 3,
 
-	/* index 4 ~ 7 are reserved */
+	/* PD state data for CONFIG_USB_PD_DUAL_ROLE uses 2 bytes */
+	BRAM_IDX_PD0 =           4,
+	BRAM_IDX_PD1 =           5,
+
+	/* index 6 ~ 7 are reserved */
 
 	BRAM_IDX_SCRATCHPAD   = 8,
 	BRAM_IDX_SCRATCHPAD1  = 9,
diff --git a/chip/it83xx/system.c b/chip/it83xx/system.c
index 055c586cd8..8ba3a970c1 100644
--- a/chip/it83xx/system.c
+++ b/chip/it83xx/system.c
@@ -232,6 +232,12 @@ static int bram_idx_lookup(enum system_bbram_idx idx)
 	    idx <= SYSTEM_BBRAM_IDX_VBNVBLOCK15)
 		return BRAM_IDX_NVCONTEXT +
 		       idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0;
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+	if (idx == SYSTEM_BBRAM_IDX_PD0)
+		return BRAM_IDX_PD0;
+	if (idx == SYSTEM_BBRAM_IDX_PD1)
+		return BRAM_IDX_PD1;
+#endif
 	return -1;
 }
 
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;
diff --git a/chip/npcx/system.c b/chip/npcx/system.c
index a747cbf866..97f2611493 100644
--- a/chip/npcx/system.c
+++ b/chip/npcx/system.c
@@ -87,7 +87,12 @@ void system_watchdog_reset(void)
 static int bbram_is_byte_access(enum bbram_data_index index)
 {
 	return (index >= BBRM_DATA_INDEX_VBNVCNTXT &&
-		index <  BBRM_DATA_INDEX_RAMLOG);
+		index <  BBRM_DATA_INDEX_RAMLOG)
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+		|| index == BBRM_DATA_INDEX_PD0
+		|| index == BBRM_DATA_INDEX_PD1
+#endif
+	;
 }
 
 /**
@@ -158,6 +163,12 @@ static int bbram_idx_lookup(enum system_bbram_idx idx)
 	    idx <= SYSTEM_BBRAM_IDX_VBNVBLOCK15)
 		return BBRM_DATA_INDEX_VBNVCNTXT +
 		       idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0;
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+	if (idx == SYSTEM_BBRAM_IDX_PD0)
+		return BBRM_DATA_INDEX_PD0;
+	if (idx == SYSTEM_BBRAM_IDX_PD1)
+		return BBRM_DATA_INDEX_PD1;
+#endif
 	return -1;
 }
 
diff --git a/chip/npcx/system_chip.h b/chip/npcx/system_chip.h
index b15c030dc4..c32c163c6a 100644
--- a/chip/npcx/system_chip.h
+++ b/chip/npcx/system_chip.h
@@ -13,6 +13,8 @@ enum bbram_data_index {
 	BBRM_DATA_INDEX_SCRATCHPAD = 0,        /* General-purpose scratchpad */
 	BBRM_DATA_INDEX_SAVED_RESET_FLAGS = 4, /* Saved reset flags */
 	BBRM_DATA_INDEX_WAKE = 8,	       /* Wake reasons for hibernate */
+	BBRM_DATA_INDEX_PD0 = 12,	       /* USB-PD saved port0 state */
+	BBRM_DATA_INDEX_PD1 = 13,	       /* USB-PD saved port1 state */
 	BBRM_DATA_INDEX_VBNVCNTXT = 16,	       /* VbNvContext for ARM arch */
 	BBRM_DATA_INDEX_RAMLOG = 32,	       /* RAM log for Booter */
 };
diff --git a/chip/stm32/system.c b/chip/stm32/system.c
index 466ebc50c9..0dfa92f44c 100644
--- a/chip/stm32/system.c
+++ b/chip/stm32/system.c
@@ -34,6 +34,8 @@ enum bkpdata_index {
 	BKPDATA_INDEX_SAVED_PANIC_INFO,      /* Saved panic data */
 	BKPDATA_INDEX_SAVED_PANIC_EXCEPTION, /* Saved panic exception code */
 #endif
+	BKPDATA_INDEX_PD0,		     /* USB-PD saved port0 state */
+	BKPDATA_INDEX_PD1,		     /* USB-PD saved port1 state */
 };
 
 /**
@@ -346,6 +348,12 @@ static int bkpdata_index_lookup(enum system_bbram_idx idx, int *msb)
 		return BKPDATA_INDEX_VBNV_CONTEXT0 +
 		       (idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0) / 2;
 	}
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+	if (idx == SYSTEM_BBRAM_IDX_PD0)
+		return BKPDATA_INDEX_PD0;
+	if (idx == SYSTEM_BBRAM_IDX_PD1)
+		return BKPDATA_INDEX_PD1;
+#endif
 	return -1;
 }
 
diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 6726e143ed..dd3bf07ba6 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -479,6 +479,25 @@ static int send_request(int port, uint32_t rdo)
 
 	return bit_len;
 }
+
+static int pd_get_saved_active(int port)
+{
+	uint8_t val;
+
+	if (system_get_bbram(port ? SYSTEM_BBRAM_IDX_PD1 :
+				    SYSTEM_BBRAM_IDX_PD0, &val)) {
+		CPRINTS("PD NVRAM FAIL");
+		return 0;
+	}
+	return !!val;
+}
+
+static void pd_set_saved_active(int port, int val)
+{
+	if (system_set_bbram(port ? SYSTEM_BBRAM_IDX_PD1 :
+				    SYSTEM_BBRAM_IDX_PD0, val))
+		CPRINTS("PD NVRAM FAIL");
+}
 #endif /* CONFIG_USB_PD_DUAL_ROLE */
 
 #ifdef CONFIG_COMMON_RUNTIME
@@ -785,6 +804,9 @@ static void handle_data_request(int port, uint16_t head,
 
 				/* explicit contract is now in place */
 				pd[port].flags |= PD_FLAGS_EXPLICIT_CONTRACT;
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+				pd_set_saved_active(port, 1);
+#endif
 				pd[port].requested_idx = RDO_POS(payload[0]);
 				set_state(port, PD_STATE_SRC_ACCEPTED);
 				return;
@@ -1055,6 +1077,7 @@ static void handle_ctrl_request(int port, uint16_t head,
 		} else if (pd[port].task_state == PD_STATE_SNK_REQUESTED) {
 			/* explicit contract is now in place */
 			pd[port].flags |= PD_FLAGS_EXPLICIT_CONTRACT;
+			pd_set_saved_active(port, 1);
 			set_state(port, PD_STATE_SNK_TRANSITION);
 #endif
 		}
@@ -1414,11 +1437,12 @@ static void pd_partner_port_reset(int port)
 	uint64_t timeout;
 
 	/*
-	 * If we already ran RO, then PD comms were disabled, and we are
-	 * already in a known state. Likewise, if the board is powering up,
-	 * we're also in a known state.
+	 * Check our battery-backed previous port state. If PD comms were
+	 * active, and we didn't just lose power, make sure we
+	 * don't boot into RO with a pre-existing power contract.
 	 */
-	if (system_get_image_copy() != SYSTEM_IMAGE_RO ||
+	if (!pd_get_saved_active(port) ||
+	   system_get_image_copy() != SYSTEM_IMAGE_RO ||
 	   system_get_reset_flags() &
 	   (RESET_FLAG_BROWNOUT | RESET_FLAG_POWER_ON))
 		return;
@@ -1429,6 +1453,7 @@ static void pd_partner_port_reset(int port)
 
 	while (get_time().val < timeout && pd_is_vbus_present(port))
 		msleep(10);
+	pd_set_saved_active(port, 0);
 }
 #endif /* CONFIG_USB_PD_DUAL_ROLE */
 
diff --git a/include/system.h b/include/system.h
index 76db18053c..f8935f40e8 100644
--- a/include/system.h
+++ b/include/system.h
@@ -280,6 +280,9 @@ enum system_bbram_idx {
 	 * ...
 	 */
 	SYSTEM_BBRAM_IDX_VBNVBLOCK15 = 15,
+	/* PD state for CONFIG_USB_PD_DUAL_ROLE uses one byte per port */
+	SYSTEM_BBRAM_IDX_PD0,
+	SYSTEM_BBRAM_IDX_PD1,
 };
 
 /**