samus_pd: Request different DP pin modes including multi-function.

Previously samus_pd just picked pin mode E without regard to what the
UFP was requesting.  This change surveys the UFP's DP pin capabilities
and then requests the appropriate pin config.

Additionally if the UFP supports multi-function and has preferred it
during the initial DP status message, samus will configure its
type-c mux in 'dock' mode.

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

BRANCH=samus
BUG=chrome-os-partner:38728
TEST=manual,
1. hoho + samus, pin mode = 'C'
2. dingdong + samus, pin mode = 'E'.
3. apple type-C HDMI multiport + samus, pin mode = 'D' and USB device
   enumerates as SuperSpeed.
4. plankton + samus w/ patch asserting alternate mode with
   multi-function preferred sets config to 'F' now and only drives DP
   out on 2 lanes w/ other two allowing USB key to be seen.

Change-Id: Ie4764c33f108e8a88f0052b64ddb96cb92e5a78b
Reviewed-on: https://chromium-review.googlesource.com/267796
Commit-Queue: Todd Broch <tbroch@chromium.org>
Tested-by: Todd Broch <tbroch@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

3 files changed, 86 insertions, 6 deletions

diff --git a/board/samus_pd/usb_pd_policy.c b/board/samus_pd/usb_pd_policy.c
index 59530116c9..a8b1f1a4b5 100644
--- a/board/samus_pd/usb_pd_policy.c
+++ b/board/samus_pd/usb_pd_policy.c
@@ -259,12 +259,15 @@ int pd_custom_vdm(int port, int cnt, uint32_t *payload,
 }
 
 static int dp_flags[PD_PORT_COUNT];
+/* DP Status VDM as returned by UFP */
+static uint32_t dp_status[PD_PORT_COUNT];
 
 static void svdm_safe_dp_mode(int port)
 {
 	/* make DP interface safe until configure */
 	board_set_usb_mux(port, TYPEC_MUX_NONE, pd_get_polarity(port));
 	dp_flags[port] = 0;
+	dp_status[port] = 0;
 }
 
 static int svdm_enter_dp_mode(int port, uint32_t mode_caps)
@@ -297,10 +300,18 @@ static int svdm_dp_status(int port, uint32_t *payload)
 static int svdm_dp_config(int port, uint32_t *payload)
 {
 	int opos = pd_alt_mode(port, USB_SID_DISPLAYPORT);
-	board_set_usb_mux(port, TYPEC_MUX_DP, pd_get_polarity(port));
+	int mf_pref = PD_VDO_DPSTS_MF_PREF(dp_status[port]);
+	int pin_mode = pd_dfp_dp_get_pin_mode(port, dp_status[port]);
+
+	if (!pin_mode)
+		return 0;
+
+	board_set_usb_mux(port, mf_pref ? TYPEC_MUX_DOCK : TYPEC_MUX_DP,
+			  pd_get_polarity(port));
+
 	payload[0] = VDO(USB_SID_DISPLAYPORT, 1,
 			 CMD_DP_CONFIG | VDO_OPOS(opos));
-	payload[1] = VDO_DP_CFG(MODE_DP_PIN_E, /* UFP_U as UFP_D */
+	payload[1] = VDO_DP_CFG(pin_mode,      /* UFP_U as UFP_D */
 				0,             /* UFP_U as DFP_D */
 				1,             /* DPv1.3 signaling */
 				2);            /* UFP_U connected as UFP_D */
@@ -335,11 +346,13 @@ DECLARE_DEFERRED(hpd1_irq_deferred);
 static int svdm_dp_attention(int port, uint32_t *payload)
 {
 	int cur_lvl;
-	int lvl = PD_VDO_HPD_LVL(payload[1]);
-	int irq = PD_VDO_HPD_IRQ(payload[1]);
+	int lvl = PD_VDO_DPSTS_HPD_LVL(payload[1]);
+	int irq = PD_VDO_DPSTS_HPD_IRQ(payload[1]);
 	enum gpio_signal hpd = PORT_TO_HPD(port);
 	cur_lvl = gpio_get_level(hpd);
 
+	dp_status[port] = payload[1];
+
 	/* Its initial DP status message prior to config */
 	if (!(dp_flags[port] & DP_FLAGS_DP_ON)) {
 		if (lvl)
diff --git a/common/usb_pd_policy.c b/common/usb_pd_policy.c
index 9d12b48434..bd0915a50b 100644
--- a/common/usb_pd_policy.c
+++ b/common/usb_pd_policy.c
@@ -406,6 +406,53 @@ static void dfp_consume_attention(int port, uint32_t *payload)
 		modep->fx->attention(port, payload);
 }
 
+/*
+ * This algorithm defaults to choosing higher pin config over lower ones.  Pin
+ * configs are organized in pairs with the following breakdown.
+ *
+ *  NAME | SIGNALING | OUTPUT TYPE | MULTI-FUNCTION | PIN CONFIG
+ * -------------------------------------------------------------
+ *  A    |  USB G2   |  ?          | no             | 00_0001
+ *  B    |  USB G2   |  ?          | yes            | 00_0010
+ *  C    |  DP       |  CONVERTED  | no             | 00_0100
+ *  D    |  PD       |  CONVERTED  | yes            | 00_1000
+ *  E    |  DP       |  DP         | no             | 01_0000
+ *  F    |  PD       |  DP         | yes            | 10_0000
+ *
+ * if UFP has NOT asserted multi-function preferred code masks away B/D/F
+ * leaving only A/C/E.  For single-output dongles that should leave only one
+ * possible pin config depending on whether its a converter DP->(VGA|HDMI) or DP
+ * output.  If someone creates a multi-output dongle presumably they would need
+ * to either offer different mode capabilities depending upon connection type or
+ * the DFP would need additional system policy to expose those options.
+ */
+int pd_dfp_dp_get_pin_mode(int port, uint32_t status)
+{
+	struct svdm_amode_data *modep = get_modep(port, USB_SID_DISPLAYPORT);
+	uint32_t mode_caps;
+	uint32_t pin_caps;
+	if (!modep)
+		return 0;
+
+	mode_caps = modep->data->mode_vdo[modep->opos - 1];
+
+	/* TODO(crosbug.com/p/39656) revisit with DFP that can be a sink */
+	pin_caps = PD_VDO_MODE_DP_SRCP(mode_caps);
+
+	/* if don't want multi-function then ignore those pin configs */
+	if (!PD_VDO_DPSTS_MF_PREF(status))
+		pin_caps &= ~MODE_DP_PIN_MF_MASK;
+
+	/* TODO(crosbug.com/p/39656) revisit if DFP drives USB Gen 2 signals */
+	pin_caps &= ~MODE_DP_PIN_BR2_MASK;
+
+	/* get_next_bit returns undefined for zero */
+	if (!pin_caps)
+		return 0;
+
+	return 1 << get_next_bit(&pin_caps);
+}
+
 int pd_dfp_exit_mode(int port, uint16_t svid, int opos)
 {
 	struct svdm_amode_data *modep;
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 3c0c48e07a..30e25d949a 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -487,12 +487,22 @@ struct pd_policy {
 	(((snkp) & 0xff) << 16 | ((srcp) & 0xff) << 8			\
 	 | ((usb) & 1) << 7 | ((gdr) & 1) << 6 | ((sign) & 0xF) << 2	\
 	 | ((sdir) & 0x3))
+#define PD_VDO_MODE_DP_SNKP(x) (((x) >> 16) & 0x3f)
+#define PD_VDO_MODE_DP_SRCP(x) (((x) >> 8) & 0x3f)
 
 #define MODE_DP_PIN_A 0x01
 #define MODE_DP_PIN_B 0x02
 #define MODE_DP_PIN_C 0x04
 #define MODE_DP_PIN_D 0x08
 #define MODE_DP_PIN_E 0x10
+#define MODE_DP_PIN_F 0x20
+
+/* Pin configs B/D/F support multi-function */
+#define MODE_DP_PIN_MF_MASK 0x2a
+/* Pin configs A/B support BR2 signaling levels */
+#define MODE_DP_PIN_BR2_MASK 0x3
+/* Pin configs C/D/E/F support DP signaling levels */
+#define MODE_DP_PIN_DP_MASK 0x3c
 
 #define MODE_DP_V13  0x1
 #define MODE_DP_GEN2 0x2
@@ -520,8 +530,9 @@ struct pd_policy {
 	 | ((usbc) & 1) << 5 | ((mf) & 1) << 4 | ((en) & 1) << 3	\
 	 | ((lp) & 1) << 2 | ((conn & 0x3) << 0))
 
-#define PD_VDO_HPD_IRQ(x) ((x >> 8) & 1)
-#define PD_VDO_HPD_LVL(x) ((x >> 7) & 1)
+#define PD_VDO_DPSTS_HPD_IRQ(x) (((x) >> 8) & 1)
+#define PD_VDO_DPSTS_HPD_LVL(x) (((x) >> 7) & 1)
+#define PD_VDO_DPSTS_MF_PREF(x) (((x) >> 4) & 1)
 
 #define HPD_DEBOUNCE_LVL (100*MSEC)
 #define HPD_DEBOUNCE_IRQ (2*MSEC)
@@ -1019,6 +1030,15 @@ int pd_custom_flash_vdm(int port, int cnt, uint32_t *payload);
 uint32_t pd_dfp_enter_mode(int port, uint16_t svid, int opos);
 
 /**
+ *  Get DisplayPort pin mode for DFP to request from UFP's capabilities.
+ *
+ * @param port     USB-C port number.
+ * @param status   DisplayPort Status VDO.
+ * @return one-hot PIN config to request.
+ */
+int pd_dfp_dp_get_pin_mode(int port, uint32_t status);
+
+/**
  * Exit alternate mode on DFP
  *
  * @param port USB-C port number