pd: Add DFP parsing for alternate mode status & attention.

Once alternate mode is entered the DFP will make an initial status
request to the UFP.  Future status changes on the UFP are then sent to
the DFP via the attention command.  This VDM consists of the VDM
header plus another VDO containing mode specific information.

CL adds ability of DFP to consume the attention VDMs status message
and in the case of DisplayPort SID toggle the necessary HPD gpio
accordingly.

BRANCH=samus
BUG=chrome-os-partner:30645
TEST=manual, for DFP w/ HPD over CC see HPD toggle correctly without
manually driving it providing cable connected when AMA is inserted.

Change-Id: Ifef60b5d0170cbcc1b518e3b13e84bac99a17e32
Signed-off-by: Todd Broch <tbroch@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/224769
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 22 insertions, 24 deletions

diff --git a/board/hoho/usb_pd_policy.c b/board/hoho/usb_pd_policy.c
index 61457d3d6c..b747766aa9 100644
--- a/board/hoho/usb_pd_policy.c
+++ b/board/hoho/usb_pd_policy.c
@@ -124,7 +124,14 @@ static int svdm_response_svids(int port, uint32_t *payload)
 	return 2;
 }
 
-const uint32_t vdo_dp_mode[1] =  {
+/* Will only ever be a single mode for this UFP_D device as it has no USB
+ * support (2.0 or 3.0) making it only PIN_E configureable nor does it have any
+ * source functionality.
+ */
+#define MODE_CNT 1
+#define OPOS 1
+
+const uint32_t vdo_dp_mode[MODE_CNT] =  {
 	VDO_MODE_DP(0,		   /* UFP pin cfg supported : none */
 		    MODE_DP_PIN_C, /* DFP pin cfg supported */
 		    1,		   /* no usb2.0	signalling in AMode */
@@ -135,39 +142,30 @@ const uint32_t vdo_dp_mode[1] =  {
 
 static int svdm_response_modes(int port, uint32_t *payload)
 {
-	int mode_cnt = ARRAY_SIZE(vdo_dp_mode);
-
 	if (PD_VDO_VID(payload[0]) != USB_SID_DISPLAYPORT) {
 		/* TODO(tbroch) USB billboard enabled here then */
 		return 1; /* will generate a NAK */
 	}
 
 	memcpy(payload + 1, vdo_dp_mode, sizeof(vdo_dp_mode));
-	return mode_cnt + 1;
-}
-
-static int hpd_get_irq(int port)
-{
-	/* TODO(tbroch) FIXME */
-	return 0;
-}
-
-static enum hpd_level hpd_get_level(int port)
-{
-	return gpio_get_level(GPIO_DP_HPD);
+	return MODE_CNT + 1;
 }
 
 static int dp_status(int port, uint32_t *payload)
 {
-	uint32_t ufp_dp_sts = payload[1] & 0x3;
-	payload[1] = VDO_DP_STATUS(hpd_get_irq(port), /* IRQ_HPD */
-				   hpd_get_level(port), /* HPD_HI|LOW */
-				   0,                 /* request exit DP */
-				   0,                 /* request exit USB */
-				   0,                 /* MF pref */
+	int opos = PD_VDO_OPOS(payload[0]);
+	int hpd = gpio_get_level(GPIO_DP_HPD);
+	if (opos != OPOS)
+		return 0; /* nak */
+
+	payload[1] = VDO_DP_STATUS(0,                /* IRQ_HPD */
+				   (hpd == 1),       /* HPD_HI|LOW */
+				   0,		     /* request exit DP */
+				   0,		     /* request exit USB */
+				   0,		     /* MF pref */
 				   gpio_get_level(GPIO_PD_SBU_ENABLE),
-				   0,                 /* power low */
-				   (ufp_dp_sts | 0x2));
+				   0,		     /* power low */
+				   0x2);
 	return 2;
 }
 
@@ -182,7 +180,7 @@ static int svdm_enter_mode(int port, uint32_t *payload)
 {
 	/* SID & mode request is valid */
 	if ((PD_VDO_VID(payload[0]) != USB_SID_DISPLAYPORT) ||
-	    (PD_VDO_OPOS(payload[0]) != 1))
+	    (PD_VDO_OPOS(payload[0]) != OPOS))
 		return 0; /* will generate a NAK */
 	return 1;
 }