servo_v4: Monitor HPD and signal DUT over PD comm

It monitors the HPD coming from the external monitor and generates the
PD message to signal DUT for HPD high/low or HPD IRQ event.

This monitoring logic is only enabled when CCD mode disabled.

BRANCH=servo
BUG=b:137219603
TEST=Configured to disable dts-mode, plugged a monitor, plugged the
Type-C cable to DUT, tried pluging and unplugging the monitor working
well.

Change-Id: I6b3f9c635dc8d5907a16c3bd9cf203da94e64f7b
Signed-off-by: Wai-Hong Tam <waihong@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1868925
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

2 files changed, 93 insertions, 5 deletions

diff --git a/board/servo_v4/board.c b/board/servo_v4/board.c
index 0cd5af7f24..5dc2b18ed5 100644
--- a/board/servo_v4/board.c
+++ b/board/servo_v4/board.c
@@ -29,10 +29,14 @@
 #include "usb_gpio.h"
 #include "usb_i2c.h"
 #include "usb_pd.h"
+#include "usb_pd_config.h"
 #include "usb_spi.h"
 #include "usb-stream.h"
 #include "util.h"
 
+#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
+#define CPRINTF(format, args...) cprintf(CC_SYSTEM, format, ## args)
+
 /******************************************************************************
  * GPIO interrupt handlers.
  */
@@ -47,10 +51,88 @@ static void vbus1_evt(enum gpio_signal signal)
 	task_wake(TASK_ID_PD_C1);
 }
 
-#include "gpio_list.h"
+static volatile uint64_t hpd_prev_ts;
+static volatile int hpd_prev_level;
 
-#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
-#define CPRINTF(format, args...) cprintf(CC_SYSTEM, format, ## args)
+/**
+ * Hotplug detect deferred task
+ *
+ * Called after level change on hpd GPIO to evaluate (and debounce) what event
+ * has occurred.  There are 3 events that occur on HPD:
+ *    1. low  : downstream display sink is deattached
+ *    2. high : downstream display sink is attached
+ *    3. irq  : downstream display sink signalling an interrupt.
+ *
+ * The debounce times for these various events are:
+ *   HPD_USTREAM_DEBOUNCE_LVL : min pulse width of level value.
+ *   HPD_USTREAM_DEBOUNCE_IRQ : min pulse width of IRQ low pulse.
+ *
+ * lvl(n-2) lvl(n-1)  lvl   prev_delta  now_delta event
+ * ----------------------------------------------------
+ * 1        0         1     <IRQ        n/a       low glitch (ignore)
+ * 1        0         1     >IRQ        <LVL      irq
+ * x        0         1     n/a         >LVL      high
+ * 0        1         0     <LVL        n/a       high glitch (ignore)
+ * x        1         0     n/a         >LVL      low
+ */
+
+void hpd_irq_deferred(void)
+{
+	int dp_mode = pd_alt_mode(1, USB_SID_DISPLAYPORT);
+
+	if (dp_mode) {
+		pd_send_hpd(DUT, hpd_irq);
+		CPRINTS("HPD IRQ");
+	}
+}
+DECLARE_DEFERRED(hpd_irq_deferred);
+
+void hpd_lvl_deferred(void)
+{
+	int level = gpio_get_level(GPIO_DP_HPD);
+	int dp_mode = pd_alt_mode(1, USB_SID_DISPLAYPORT);
+
+	if (level != hpd_prev_level) {
+		/* It's a glitch while in deferred or canceled action */
+		return;
+	}
+
+	if (dp_mode) {
+		pd_send_hpd(DUT, level ? hpd_high : hpd_low);
+		CPRINTS("HPD: %d", level);
+	}
+}
+DECLARE_DEFERRED(hpd_lvl_deferred);
+
+void hpd_evt(enum gpio_signal signal)
+{
+	timestamp_t now = get_time();
+	int level = gpio_get_level(signal);
+	uint64_t cur_delta = now.val - hpd_prev_ts;
+
+	/* Store current time */
+	hpd_prev_ts = now.val;
+
+	/* All previous hpd level events need to be re-triggered */
+	hook_call_deferred(&hpd_lvl_deferred_data, -1);
+
+	/* It's a glitch.  Previous time moves but level is the same. */
+	if (cur_delta < HPD_USTREAM_DEBOUNCE_IRQ)
+		return;
+
+	if ((!hpd_prev_level && level) &&
+	    (cur_delta < HPD_USTREAM_DEBOUNCE_LVL)) {
+		/* It's an irq */
+		hook_call_deferred(&hpd_irq_deferred_data, 0);
+	} else if (cur_delta >= HPD_USTREAM_DEBOUNCE_LVL) {
+		hook_call_deferred(&hpd_lvl_deferred_data,
+				   HPD_USTREAM_DEBOUNCE_LVL);
+	}
+
+	hpd_prev_level = level;
+}
+
+#include "gpio_list.h"
 
 /******************************************************************************
  * Board pre-init function.
@@ -390,8 +472,15 @@ static void ccd_measure_sbu(void)
 void ccd_enable(int enable)
 {
 	if (enable) {
+		gpio_disable_interrupt(GPIO_DP_HPD);
 		hook_call_deferred(&ccd_measure_sbu_data, 0);
 	} else {
+		timestamp_t now = get_time();
+
+		hpd_prev_level = gpio_get_level(GPIO_DP_HPD);
+		hpd_prev_ts = now.val;
+		gpio_enable_interrupt(GPIO_DP_HPD);
+
 		gpio_set_level(GPIO_SBU_MUX_EN, 0);
 		hook_call_deferred(&ccd_measure_sbu_data, -1);
 	}
@@ -462,6 +551,5 @@ static void board_init(void)
 	gpio_enable_interrupt(GPIO_USB_DET_PP_DUT);
 
 	hook_call_deferred(&ccd_measure_sbu_data, 1000 * MSEC);
-
 }
 DECLARE_HOOK(HOOK_INIT, board_init, HOOK_PRIO_DEFAULT);
diff --git a/board/servo_v4/gpio.inc b/board/servo_v4/gpio.inc
index f087c633ca..76b9a06d0f 100644
--- a/board/servo_v4/gpio.inc
+++ b/board/servo_v4/gpio.inc
@@ -7,6 +7,7 @@
 
 GPIO_INT(USB_DET_PP_CHG,	PIN(C, 13), GPIO_INT_BOTH, vbus0_evt)
 GPIO_INT(USB_DET_PP_DUT,	PIN(C, 12), GPIO_INT_BOTH, vbus1_evt)
+GPIO_INT(DP_HPD,                PIN(A, 14), GPIO_INT_BOTH, hpd_evt)
 
 /* Outputs */
 GPIO(DUT_CHG_EN,		PIN(A, 10), GPIO_OUT_LOW)
@@ -26,7 +27,6 @@ GPIO(EMMC_MUX_EN_L,		PIN(F, 0),  GPIO_OUT_HIGH)
 GPIO(EMMC_PWR_EN,		PIN(F, 1),  GPIO_OUT_LOW)
 
 /* Inputs */
-GPIO(DP_HPD,			PIN(A, 14), GPIO_INPUT)
 GPIO(USERVO_FAULT_L,		PIN(A, 8),  GPIO_INPUT)
 GPIO(USB_FAULT_L,		PIN(A, 9),  GPIO_INPUT)
 GPIO(DONGLE_DET,		PIN(C, 15), GPIO_INPUT)