servo_v4p1: Add CCD measurement functionality

The CCD measurement functionality is only
available in RO.

BRANCH=none
BUG=b:146793000
TEST=make -j buildall

Signed-off-by: Sam Hurst <shurst@google.com>
Change-Id: I4bf9885a8a76c8d9dbb688a72673726fb0a7efa5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2216402
Reviewed-by: Wai-Hong Tam <waihong@google.com>

1 files changed, 131 insertions, 0 deletions

diff --git a/board/servo_v4p1/ccd_measure_sbu.c b/board/servo_v4p1/ccd_measure_sbu.c
new file mode 100644
index 0000000000..b9c9680cc9
--- /dev/null
+++ b/board/servo_v4p1/ccd_measure_sbu.c
@@ -0,0 +1,131 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+/* CCD Measure SBU */
+
+#include "adc.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "ioexpanders.h"
+#include "timer.h"
+
+#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
+#define CPRINTF(format, args...) cprintf(CC_SYSTEM, format, ## args)
+
+/*
+ * Define voltage thresholds for SBU USB detection.
+ *
+ * Max observed USB low across sampled systems: 666mV
+ * Min observed USB high across sampled systems: 3026mV
+ */
+#define GND_MAX_MV      700
+#define USB_HIGH_MV     2500
+#define SBU_DIRECT      0
+#define SBU_FLIP        1
+
+#define MODE_SBU_DISCONNECT     0
+#define MODE_SBU_CONNECT        1
+#define MODE_SBU_FLIP           2
+#define MODE_SBU_OTHER          3
+
+static void ccd_measure_sbu(void);
+DECLARE_DEFERRED(ccd_measure_sbu);
+static void ccd_measure_sbu(void)
+{
+	int sbu1;
+	int sbu2;
+	int mux_en;
+	static int count /* = 0 */;
+	static int last /* = 0 */;
+	static int polarity /* = 0 */;
+
+	/* Read sbu voltage levels */
+	sbu1 = adc_read_channel(ADC_SBU1_DET);
+	sbu2 = adc_read_channel(ADC_SBU2_DET);
+	mux_en = gpio_get_level(GPIO_SBU_MUX_EN);
+
+	/*
+	 * While SBU_MUX is disabled (SuzyQ unplugged), we'll poll the SBU lines
+	 * to check if an idling, unconfigured USB device is present.
+	 * USB FS pulls one line high for connect request.
+	 * If so, and it persists for 500ms, we'll enable the SuzyQ in that
+	 * orientation.
+	 */
+	if ((!mux_en) && (sbu1 > USB_HIGH_MV) && (sbu2 < GND_MAX_MV)) {
+		/* Check flip connection polarity. */
+		if (last != MODE_SBU_FLIP) {
+			last = MODE_SBU_FLIP;
+			polarity = SBU_FLIP;
+			count = 0;
+		} else {
+			count++;
+		}
+	} else if ((!mux_en) && (sbu2 > USB_HIGH_MV) && (sbu1 < GND_MAX_MV)) {
+		/* Check direct connection polarity. */
+		if (last != MODE_SBU_CONNECT) {
+			last = MODE_SBU_CONNECT;
+			polarity = SBU_DIRECT;
+			count = 0;
+		} else {
+			count++;
+		}
+		/*
+		 * If SuzyQ is enabled, we'll poll for a persistent no-signal
+		 * for 500ms. Since USB is differential, we should never see
+		 * GND/GND while the device is connected.
+		 * If disconnected, electrically remove SuzyQ.
+		 */
+	} else if ((mux_en) && (sbu1 < GND_MAX_MV) && (sbu2 < GND_MAX_MV)) {
+		/* Check for SBU disconnect if connected. */
+		if (last != MODE_SBU_DISCONNECT) {
+			last = MODE_SBU_DISCONNECT;
+			count = 0;
+		} else {
+			count++;
+		}
+	} else {
+		/* Didn't find anything, reset state. */
+		last = MODE_SBU_OTHER;
+		count = 0;
+	}
+
+	/*
+	 * We have seen a new state continuously for 500ms.
+	 * Let's update the mux to enable/disable SuzyQ appropriately.
+	 */
+	if (count > 5) {
+		if (mux_en) {
+			/* Disable mux as it's disconnected now. */
+			gpio_set_level(GPIO_SBU_MUX_EN, 0);
+			msleep(10);
+			CPRINTS("CCD: disconnected.");
+		} else {
+			/* SBU flip = polarity */
+			sbu_flip_sel(polarity);
+			gpio_set_level(GPIO_SBU_MUX_EN, 1);
+			msleep(10);
+			CPRINTS("CCD: connected %s",
+				polarity ? "flip" : "noflip");
+		}
+	}
+
+	/* Measure every 100ms, forever. */
+	hook_call_deferred(&ccd_measure_sbu_data, 100 * MSEC);
+}
+
+void ccd_enable(int enable)
+{
+	if (enable) {
+		hook_call_deferred(&ccd_measure_sbu_data, 0);
+	} else {
+		gpio_set_level(GPIO_SBU_MUX_EN, 0);
+		hook_call_deferred(&ccd_measure_sbu_data, -1);
+	}
+}
+
+void start_ccd_meas_sbu_cycle(void)
+{
+	hook_call_deferred(&ccd_measure_sbu_data, 1000 * MSEC);
+}