pd: refactor object position index.

Renaming this to 'opos' for consistency with USP-PD specifications
'object position' in VDM header.

Signed-off-by: Todd Broch <tbroch@chromium.org>

BRANCH=samus
BUG=chrome-os-partner:35495
TEST=manual, On hoho
1. Still successfully enter default mode DP
2. Using ectool's pdgetmode pdsetmode can successfully enter/exit
other modes
3. Works across hard & soft resets

Original-Change-Id: I08cb8e003ced4de481adcb503bcba3437ebb1ab7
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/243464
(cherry picked from commit 3850a013f1bf39919633ea9e6a19d2800b52ef2c)
Signed-off-by: Todd Broch <tbroch@chromium.org>

Change-Id: I395a36eee8f4403707dde08053ff98a2dbe6a3a6
Reviewed-on: https://chromium-review.googlesource.com/244230
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>
Commit-Queue: Todd Broch <tbroch@chromium.org>

4 files changed, 19 insertions, 23 deletions

diff --git a/common/usb_pd_policy.c b/common/usb_pd_policy.c
index 9aa0e7e083..3c6900c532 100644
--- a/common/usb_pd_policy.c
+++ b/common/usb_pd_policy.c
@@ -165,12 +165,9 @@ unsigned pd_get_max_voltage(void)
 
 static struct pd_policy pe[PD_PORT_COUNT];
 
-#define AMODE_VALID(port) (pe[port].amode.index != -1)
-
 void pd_dfp_pe_init(int port)
 {
 	memset(&pe[port], 0, sizeof(struct pd_policy));
-	pe[port].amode.index = -1;
 }
 
 static void dfp_consume_identity(int port, uint32_t *payload)
@@ -253,11 +250,7 @@ static void dfp_consume_modes(int port, int cnt, uint32_t *payload)
 
 int pd_alt_mode(int port)
 {
-	if (!AMODE_VALID(port))
-		/* zero is reserved */
-		return 0;
-
-	return pe[port].amode.index + 1;
+	return pe[port].amode.opos;
 }
 
 /* Enter default mode or attempt to enter mode via svid & index arguments */
@@ -276,12 +269,12 @@ static int dfp_enter_mode(int port, uint32_t *payload, int use_payload)
 				continue;
 			modep->fx = &supported_modes[i];
 			modep->mode_caps = pe[port].svids[j].mode_vdo[0];
-			modep->index = (opos && (opos < 7)) ? opos - 1 : 0;
+			modep->opos = (opos && (opos < 7)) ? opos : 1;
 			done = 1;
 			break;
 		}
 	}
-	if (!AMODE_VALID(port))
+	if (!modep->opos)
 		return 0;
 
 	if (modep->fx->enter(port, modep->mode_caps) == -1)
@@ -297,7 +290,7 @@ static void dfp_consume_attention(int port, uint32_t *payload)
 	int svid = PD_VDO_VID(payload[0]);
 	int opos = PD_VDO_OPOS(payload[0]);
 
-	if (!AMODE_VALID(port))
+	if (!pe[port].amode.opos)
 		return;
 	if (svid != pe[port].amode.fx->svid) {
 		CPRINTF("PE ERR: svid s:0x%04x != m:0x%04x\n",
@@ -327,7 +320,7 @@ uint32_t pd_dfp_exit_mode(int port)
 	 * to exit all modes.
 	 */
 	if (pd_is_connected(port)) {
-		modep->index = -1;
+		modep->opos = 0;
 		return VDO(modep->fx->svid, 1,
 			   (CMD_EXIT_MODE | VDO_OPOS(pd_alt_mode(port))));
 	} else {
@@ -373,7 +366,7 @@ static void dump_pe(int port)
 				 pe[port].svids[i].mode_vdo[j]);
 		ccprintf("\n");
 	}
-	if (!AMODE_VALID(port)) {
+	if (!modep->opos) {
 		ccprintf("No mode chosen yet.\n");
 		return;
 	}
@@ -488,9 +481,9 @@ int pd_svdm(int port, int cnt, uint32_t *payload, uint32_t **rpayload)
 			 * TODO(crosbug.com/p/33946): Fix won't allow multiple
 			 * mode entry.
 			 */
-			if (!AMODE_VALID(port))
+			if (!pe[port].amode.opos)
 				dfp_enter_mode(port, payload, 1);
-			if (AMODE_VALID(port)) {
+			if (pe[port].amode.opos) {
 				rsize = pe[port].amode.fx->status(port,
 								  payload);
 				payload[0] |= VDO_OPOS(pd_alt_mode(port));
@@ -500,14 +493,14 @@ int pd_svdm(int port, int cnt, uint32_t *payload, uint32_t **rpayload)
 			/* DP status response & UFP's DP attention have same
 			   payload */
 			dfp_consume_attention(port, payload);
-			if (AMODE_VALID(port))
+			if (pe[port].amode.opos)
 				rsize = pe[port].amode.fx->config(port,
 								  payload);
 			else
 				rsize = 0;
 			break;
 		case CMD_DP_CONFIG:
-			if (AMODE_VALID(port) &&
+			if (pe[port].amode.opos &&
 			    pe[port].amode.fx->post_config)
 				pe[port].amode.fx->post_config(port);
 			/* no response after DFPs ack */
@@ -628,9 +621,9 @@ static int hc_remote_pd_get_amode(struct host_cmd_handler_args *args)
 	r->active = 0;
 	memcpy(r->vdo, pe[p->port].svids[p->svid_idx].mode_vdo, 24);
 
-	if (AMODE_VALID(p->port) && pe[p->port].amode.fx->svid == r->svid) {
+	if (pe[p->port].amode.opos && pe[p->port].amode.fx->svid == r->svid) {
 		r->active = 1;
-		r->idx = pd_alt_mode(p->port) - 1;
+		r->opos = pd_alt_mode(p->port);
 	}
 	args->response_size = sizeof(*r);
 	return EC_RES_SUCCESS;
diff --git a/include/ec_commands.h b/include/ec_commands.h
index 18e9e454f7..926e317eee 100644
--- a/include/ec_commands.h
+++ b/include/ec_commands.h
@@ -2930,7 +2930,7 @@ struct ec_params_usb_pd_get_mode_request {
 struct ec_params_usb_pd_get_mode_response {
 	uint16_t svid;   /* SVID */
 	uint8_t active;  /* Active SVID */
-	uint8_t idx;     /* Index of active mode VDO. Ignored if !active */
+	uint8_t opos;    /* Object Position */
 	uint32_t vdo[6]; /* Mode VDOs */
 } __packed;
 
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 14b83ae41b..27c3ae1740 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -189,9 +189,12 @@ extern const struct svdm_response svdm_rsp;
 extern const struct svdm_amode_fx supported_modes[];
 extern const int supported_modes_cnt;
 
+/* DFP data needed to support alternate mode entry and exit */
 struct svdm_amode_data {
 	const struct svdm_amode_fx *fx;
-	int index;
+	/* VDM object position */
+	int opos;
+	/* mode capabilities specific to SVID amode. */
 	uint32_t mode_caps;
 };
 
diff --git a/util/ectool.c b/util/ectool.c
index f98a98a943..de1b378fdc 100644
--- a/util/ectool.c
+++ b/util/ectool.c
@@ -876,7 +876,7 @@ static int in_gfu_mode(int *opos, int port)
 		}
 	}
 
-	return r->active && ((r->idx + 1) == *opos);
+	return r->active && (r->opos == *opos);
 }
 
 /**
@@ -1168,7 +1168,7 @@ int cmd_pd_get_amode(int argc, char *argv[])
 		printf("%cSVID:0x%04x ", (r->active) ? '*' : ' ',
 		       r->svid);
 		for (i = 0; i < PDO_MODES; i++) {
-			printf("%c0x%08x ", (r->active && (r->idx == i)) ?
+			printf("%c0x%08x ", (r->active && (r->opos == i + 1)) ?
 			       '*' : ' ', r->vdo[i]);
 		}
 		printf("\n");