honeybuns: Set lane control gpio when MST is in reset

GPIO_MST_HUB_LANE_SWITCH is used by the EC to signal to the MST hub if
the host will be providing 2 or 4 lanes of DP. Some MST hubs will only
read this signal coming out of reset.

This CL adds a method to set MST_HUB_LANE_SWITCH which includes
putting the MST hub in reset.

BUG=b:175434634
BRANCH=None
TEST=modified the mf preference in CBI and verified that
MST_HUB_LANE_SWITCH follows the expected level based on pin config in
the DP Configure message:
Pin Config C -> 0* MST_HUB_LANE_SWITCH
Pin Config D -> 1* MST_HUB_LANE_SWITCH

Signed-off-by: Scott Collyer <scollyer@google.com>
Change-Id: I096988567b1e53cf49833359ce053da199f406db
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2682789
Commit-Queue: Scott Collyer <scollyer@chromium.org>
Tested-by: Scott Collyer <scollyer@chromium.org>
Reviewed-by: Diana Z <dzigterman@chromium.org>

3 files changed, 54 insertions, 1 deletions

diff --git a/baseboard/honeybuns/baseboard.c b/baseboard/honeybuns/baseboard.c
index cd21c22492..3b6d4ba626 100644
--- a/baseboard/honeybuns/baseboard.c
+++ b/baseboard/honeybuns/baseboard.c
@@ -5,6 +5,7 @@
 
 /* Honeybuns family-specific configuration */
 #include "console.h"
+#include "cros_board_info.h"
 #include "gpio.h"
 #include "hooks.h"
 #include "i2c.h"
@@ -38,8 +39,29 @@ const struct i2c_port_t i2c_ports[] = {
 };
 const unsigned int i2c_ports_used = ARRAY_SIZE(i2c_ports);
 
+
+void baseboard_set_mst_lane_control(int dock_mf)
+{
+	/* Check if lane swich level is changing */
+	if (dock_mf != gpio_get_level(GPIO_MST_HUB_LANE_SWITCH)) {
+		/* put MST into reset */
+		gpio_set_level(GPIO_MST_RST_L, 0);
+		msleep(1);
+		gpio_set_level(GPIO_MST_HUB_LANE_SWITCH, dock_mf);
+		CPRINTS("MST: lane control = %s", dock_mf ? "high" : "low");
+		msleep(1);
+		/* lane control is set, take MST out of reset */
+		gpio_set_level(GPIO_MST_RST_L, 1);
+	}
+}
+
 static void baseboard_init(void)
 {
+#ifdef SECTION_IS_RW
+	int rv;
+	uint32_t fw_config;
+#endif
+
 	/* Turn on power rails */
 	board_power_sequence();
 	CPRINTS("board: Power rails enabled");
@@ -49,11 +71,20 @@ static void baseboard_init(void)
 	system_clear_reset_flags(EC_RESET_FLAG_POWER_ON);
 	/* Make certain SN5S330 PPC does full initialization */
 	system_set_reset_flags(EC_RESET_FLAG_EFS);
+
+	/*
+	 * Dock multi function (mf) preference is stored in bit 0 of fw_config
+	 * field of the CBI. If this value is programmed, then make sure the
+	 * MST_LANE_CONTROL gpio matches the mf bit.
+	 */
+	rv = cbi_get_fw_config(&fw_config);
+	if (!rv)
+		baseboard_set_mst_lane_control(fw_config & 1);
 #else
 	/* Set up host port usbc to present Rd on CC lines */
 	if(baseboard_usbc_init(USB_PD_PORT_HOST))
 		CPRINTS("usbc: Failed to set up sink path");
-#endif
+#endif /* SECTION_IS_RW */
 }
 /*
  * Power sequencing must run before any other chip init is attempted, so run
diff --git a/baseboard/honeybuns/baseboard.h b/baseboard/honeybuns/baseboard.h
index 85a877d80c..0faf727ab8 100644
--- a/baseboard/honeybuns/baseboard.h
+++ b/baseboard/honeybuns/baseboard.h
@@ -229,8 +229,22 @@ enum adc_channel {
 extern const struct power_seq board_power_seq[];
 extern const size_t board_power_seq_count;
 
+/*
+ * Configure the host port to present Rd on both CC lines. This function is
+ * called in RO which does not otherwise have usbc/usb-pd support.
+ *
+ * @return true - initialized. false - not.
+ */
 int baseboard_usbc_init(int port);
 
+/*
+ * Set MST_LANE_CONTROL gpio to match the DP pin configuration selected
+ * by the host in the DP Configure SVDM message.
+ *
+ * @param dock_mf 1 -> 2 lanes DP, 0 -> 4 lanes DP
+ */
+void baseboard_set_mst_lane_control(int dock_mf);
+
 #endif /* !__ASSEMBLER__ */
 
 #endif /* __CROS_EC_BASEBOARD_H */
diff --git a/baseboard/honeybuns/usb_pd_policy.c b/baseboard/honeybuns/usb_pd_policy.c
index 5257753204..a3b43d2402 100644
--- a/baseboard/honeybuns/usb_pd_policy.c
+++ b/baseboard/honeybuns/usb_pd_policy.c
@@ -325,6 +325,14 @@ static void svdm_configure_demux(int port, int enable, int mf)
 		/* 4 lane mode if MF is not preferred */
 		if (!mf)
 			demux &= ~USB_PD_MUX_USB_ENABLED;
+		/*
+		 * Make sure the MST_LANE_CONTROL gpio is set to match the DP
+		 * pin configuration selected by the host. Note that the mf
+		 * passed into this function reflects the pin configuration
+		 * selected by the host and not the user mf preference which is
+		 * stored in bit 0 of CBI fw_config.
+		 */
+		baseboard_set_mst_lane_control(mf);
 	} else {
 		demux &= ~USB_PD_MUX_DP_ENABLED;
 		demux |= USB_PD_MUX_USB_ENABLED;