pd: dingdong/hoho: HPD over USB PD.

HPD needs to be transported of USB PD as both SBU lines are consumed
for differential AUX signalling.

This CL does the following:
1. Enables GPIO DP_HPD as interrupt
2. Sends debounced HPD across CC via the SVDM DP status message

BRANCH=none
BUG=chrome-os-partner:31192,chrome-os-partner:31193
TEST=manual,

From servo w/ GPIO attached to HPD drove the following transactions
after inserting with HPD low initially:

    # e1: hpd_high
    # e2: hpd_low
    # non-registered glitch
    # e3: hpd_high followed by hpd_low
    # e4: hpd high
    # non-registered glitch
    # e5: hpd_irq
    # e6: hpd_irq
    # e7: hpd_irq
    # e8: hpd_low followed by hpd_high

From fruitpie console (marked up to show result of above)
----> enter-mode, dp status, dp config
	    [6.774108 DONE]   SVDM/1 [4] ff018144
	    [6.777467 DONE]   SVDM/2 [16] ff018150 00000002
	    [6.780637 DONE]   SVDM/1 [17] ff018051
----> attentions start arriving
----> e1    [18.966741 DONE]  SVDM/2 [6] ff018106 0000008a
----> e2    [33.724367 DONE]  SVDM/2 [6] ff018106 0000000a
----> e3    [64.550398 DONE]  SVDM/2 [6] ff018106 0000008a
----> e3    [64.752452 DONE]  SVDM/2 [6] ff018106 0000000a
----> e4    [74.247127 DONE]  SVDM/2 [6] ff018106 0000008a
----> e5    [88.906254 DONE]  SVDM/2 [6] ff018106 0000010a
----> e6    [100.938738 DONE] SVDM/2 [6] ff018106 0000010a
----> e7    [123.693414 DONE] SVDM/2 [6] ff018106 0000010a
----> e8    [130.050074 DONE] SVDM/2 [6] ff018106 0000000a
----> e8    [130.254087 DONE] SVDM/2 [6] ff018106 0000008a

Change-Id: I976c268467ece84cedab7ba4943fb59d1e48c113
Signed-off-by: Todd Broch <tbroch@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/223262
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

3 files changed, 92 insertions, 4 deletions

diff --git a/board/hoho/board.c b/board/hoho/board.c
index c521d2c6f8..f7ce18da4b 100644
--- a/board/hoho/board.c
+++ b/board/hoho/board.c
@@ -7,7 +7,6 @@
 #include "adc.h"
 #include "adc_chip.h"
 #include "common.h"
-#include "console.h"
 #include "gpio.h"
 #include "hooks.h"
 #include "i2c.h"
@@ -16,10 +15,80 @@
 #include "usb.h"
 #include "usb_bb.h"
 #include "usb_pd.h"
+#include "timer.h"
 #include "util.h"
 
+static volatile uint64_t hpd_prev_ts;
+static volatile int hpd_prev_level;
+
+void hpd_event(enum gpio_signal signal);
 #include "gpio_list.h"
 
+/**
+ * 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:
+ *  100MSEC : min pulse width of level value.
+ *    2MSEC : min pulse width of IRQ low pulse.  Max is level debounce min.
+ *
+ * lvl(n-2) lvl(n-1)  lvl   prev_delta  now_delta event
+ * ----------------------------------------------------
+ * 1        0         1     <2ms        n/a       low glitch (ignore)
+ * 1        0         1     >2ms        <100ms    irq
+ * x        0         1     n/a         >100ms    high
+ * 0        1         0     <100ms      n/a       high glitch (ignore)
+ * x        1         0     n/a         >100ms    low
+ */
+
+void hpd_irq_deferred(void)
+{
+	pd_send_hpd(0, hpd_irq);
+}
+DECLARE_DEFERRED(hpd_irq_deferred);
+
+void hpd_lvl_deferred(void)
+{
+	int level = gpio_get_level(GPIO_DP_HPD);
+
+	if (level != hpd_prev_level)
+		/* It's a glitch while in deferred or canceled action */
+		return;
+
+	pd_send_hpd(0, (level) ? hpd_high : hpd_low);
+}
+DECLARE_DEFERRED(hpd_lvl_deferred);
+
+void hpd_event(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, -1);
+
+	/* It's a glitch.  Previous time moves but level is the same. */
+	if (cur_delta < HPD_DEBOUNCE_IRQ)
+		return;
+
+	if ((!hpd_prev_level && level) && (cur_delta < HPD_DEBOUNCE_LVL))
+		/* It's an irq */
+		hook_call_deferred(hpd_irq_deferred, 0);
+	else if (cur_delta >= HPD_DEBOUNCE_LVL)
+		hook_call_deferred(hpd_lvl_deferred, HPD_DEBOUNCE_LVL);
+
+	hpd_prev_level = level;
+}
+
 /* Initialize board. */
 void board_config_pre_init(void)
 {
@@ -60,14 +129,22 @@ static void board_init_spi2(void)
 	/* Enable clocks to SPI2 module */
 	STM32_RCC_APB1ENR |= STM32_RCC_PB1_SPI2;
 }
+#endif /* CONFIG_SPI_FLASH */
 
 /* Initialize board. */
 static void board_init(void)
 {
+	timestamp_t now;
+#ifdef CONFIG_SPI_FLASH
 	board_init_spi2();
+#endif
+	now = get_time();
+	hpd_prev_level = gpio_get_level(GPIO_DP_HPD);
+	hpd_prev_ts = now.val;
+	gpio_enable_interrupt(GPIO_DP_HPD);
 }
+
 DECLARE_HOOK(HOOK_INIT, board_init, HOOK_PRIO_DEFAULT);
-#endif /* CONFIG_SPI_FLASH */
 
 /* ADC channels */
 const struct adc_t adc_channels[] = {
diff --git a/board/hoho/gpio.inc b/board/hoho/gpio.inc
index 204a1ac332..0aad148307 100644
--- a/board/hoho/gpio.inc
+++ b/board/hoho/gpio.inc
@@ -4,7 +4,7 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
-GPIO(DP_HPD,           A, 0,  GPIO_INPUT,    NULL)
+GPIO(DP_HPD,           A, 0,  GPIO_INT_BOTH, hpd_event)
 GPIO(USB_C_CC1_PD,     A, 1,  GPIO_ANALOG,   NULL)
 GPIO(MCDP_RESET_L,     A, 3,  GPIO_OUT_HIGH, NULL)
 GPIO(PD_DAC_REF,       A, 4,  GPIO_ANALOG,   NULL)
diff --git a/board/hoho/usb_pd_policy.c b/board/hoho/usb_pd_policy.c
index b747766aa9..f52416b19d 100644
--- a/board/hoho/usb_pd_policy.c
+++ b/board/hoho/usb_pd_policy.c
@@ -12,8 +12,8 @@
 #include "registers.h"
 #include "task.h"
 #include "timer.h"
-#include "util.h"
 #include "usb_pd.h"
+#include "util.h"
 #include "version.h"
 
 #define CPRINTF(format, args...) cprintf(CC_USBPD, format, ## args)
@@ -32,6 +32,9 @@ const int pd_snk_pdo_cnt = ARRAY_SIZE(pd_snk_pdo);
 /* Desired voltage requested as a sink (in millivolts) */
 static unsigned select_mv = 5000;
 
+/* Whether alternate mode has been entered or not */
+static int alt_mode;
+
 int pd_choose_voltage(int cnt, uint32_t *src_caps, uint32_t *rdo,
 		      uint32_t *curr_limit, uint32_t *supply_voltage)
 {
@@ -182,12 +185,20 @@ static int svdm_enter_mode(int port, uint32_t *payload)
 	if ((PD_VDO_VID(payload[0]) != USB_SID_DISPLAYPORT) ||
 	    (PD_VDO_OPOS(payload[0]) != OPOS))
 		return 0; /* will generate a NAK */
+
+	alt_mode = OPOS;
 	return 1;
 }
 
+int pd_alt_mode(int port)
+{
+	return alt_mode;
+}
+
 static int svdm_exit_mode(int port, uint32_t *payload)
 {
 	gpio_set_level(GPIO_PD_SBU_ENABLE, 0);
+	alt_mode = 0;
 	return 1; /* Must return ACK */
 }