cheza: Support base detection

The base detection logic is similar to Lux base. But Cheza one doesn't
have a battery inside. So skip the dual-battery charging logic and give
the power to the base right after it is plugged.

BRANCH=none
BUG=b:112614067
TEST=Remove the base battery. Plug and unplug the base. Check the EC
messages showing the base connected and disconnected.

Change-Id: I363860609b17ae74c09ccdb681c99123f7a38a06
Signed-off-by: Wai-Hong Tam <waihong@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1176732
Reviewed-by: Stephen Boyd <swboyd@chromium.org>

4 files changed, 194 insertions, 2 deletions

diff --git a/board/cheza/base_detect.c b/board/cheza/base_detect.c
new file mode 100644
index 0000000000..b70b6b3433
--- /dev/null
+++ b/board/cheza/base_detect.c
@@ -0,0 +1,186 @@
+/* Copyright 2018 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.
+ */
+
+/* Lux base without battery detection code */
+
+#include "adc.h"
+#include "adc_chip.h"
+#include "board.h"
+#include "chipset.h"
+#include "common.h"
+#include "console.h"
+#include "extpower.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "host_command.h"
+#include "system.h"
+#include "tablet_mode.h"
+#include "task.h"
+#include "timer.h"
+#include "util.h"
+
+#define CPRINTS(format, args...) cprints(CC_USB, format, ## args)
+#define CPRINTF(format, args...) cprintf(CC_USB, format, ## args)
+
+/* Base detection and debouncing */
+#define BASE_DETECT_DEBOUNCE_US (20 * MSEC)
+
+/*
+ * If the base status is unclear (i.e. not within expected ranges, read
+ * the ADC value again every 500ms.
+ */
+#define BASE_DETECT_RETRY_US (500 * MSEC)
+
+/*
+ * When base is disconnected, and gets connected:
+ * Lid has 1M pull-up, base has 200K pull-down, so the ADC
+ * value should be around 200/(200+1000)*3300 = 550.
+ *
+ * Idle value should be ~3300: lid has 1M pull-up, and nothing else (i.e. ADC
+ * maxing out at 2813).
+ */
+#define BASE_DISCONNECTED_CONNECT_MIN_MV 450
+#define BASE_DISCONNECTED_CONNECT_MAX_MV 650
+
+#define BASE_DISCONNECTED_MIN_MV 2800
+#define BASE_DISCONNECTED_MAX_MV (ADC_MAX_VOLT+1)
+
+/*
+ * When base is connected, then gets disconnected:
+ * Lid has 1M pull-up, lid has 10.0K pull-down, so the ADC
+ * value should be around 10.0/(10.0+1000)*3300 = 33.
+ *
+ * Idle level when connected should be:
+ * Lid has 10K pull-down, base has 5.1K pull-up, so the ADC value should be
+ * around 10.0/(10.0+5.1)*3300 = 2185 (actual value is 2153 as there is still
+ * a 1M pull-up on lid, and 200K pull-down on base).
+ */
+#define BASE_CONNECTED_DISCONNECT_MIN_MV 20
+#define BASE_CONNECTED_DISCONNECT_MAX_MV 45
+
+#define BASE_CONNECTED_MIN_MV 2050
+#define BASE_CONNECTED_MAX_MV 2300
+
+static uint64_t base_detect_debounce_time;
+
+static void base_detect_deferred(void);
+DECLARE_DEFERRED(base_detect_deferred);
+
+enum base_status {
+	BASE_UNKNOWN = 0,
+	BASE_DISCONNECTED = 1,
+	BASE_CONNECTED = 2,
+};
+
+static enum base_status current_base_status;
+
+/*
+ * This function is called whenever there is a change in the base detect
+ * status. Actions taken include:
+ * 1. Enable/disable pull-down on half-duplex UART line
+ * 2. Enable/disable power to base.
+ * 3. Indicate mode change to host.
+ * 4. Indicate tablet mode to host. Current assumption is that if base is
+ * disconnected then the system is in tablet mode, else if the base is
+ * connected, then the system is not in tablet mode.
+ */
+static void base_detect_change(enum base_status status)
+{
+	int connected = (status == BASE_CONNECTED);
+
+	if (current_base_status == status)
+		return;
+
+	current_base_status = status;
+
+	/* Enable pull-down if connected. */
+	gpio_set_level(GPIO_EN_CC_LID_BASE_PULLDN, !connected);
+
+	/* We don't enable dual-battery support. Set the base power directly. */
+	gpio_set_level(GPIO_EN_PPVAR_VAR_BASE, connected);
+
+	tablet_set_mode(!connected);
+}
+
+static void print_base_detect_value(const char *str, int v)
+{
+	CPRINTS("Base %s. ADC: %d", str, v);
+}
+
+static void base_detect_deferred(void)
+{
+	uint64_t time_now = get_time().val;
+	int v;
+
+	if (base_detect_debounce_time > time_now) {
+		hook_call_deferred(&base_detect_deferred_data,
+				   base_detect_debounce_time - time_now);
+		return;
+	}
+
+	v = adc_read_channel(ADC_BASE_DET);
+	if (v == ADC_READ_ERROR)
+		goto retry;
+
+	if (current_base_status == BASE_CONNECTED) {
+		if (v >= BASE_CONNECTED_DISCONNECT_MIN_MV &&
+		    v <= BASE_CONNECTED_DISCONNECT_MAX_MV) {
+			print_base_detect_value("disconnected", v);
+			base_detect_change(BASE_DISCONNECTED);
+			return;
+		} else if (v >= BASE_CONNECTED_MIN_MV &&
+			   v <= BASE_CONNECTED_MAX_MV) {
+			/* Still connected. */
+			return;
+		}
+	} else { /* Disconnected or unknown. */
+		if (v >= BASE_DISCONNECTED_CONNECT_MIN_MV &&
+		    v <= BASE_DISCONNECTED_CONNECT_MAX_MV) {
+			print_base_detect_value("connected", v);
+			base_detect_change(BASE_CONNECTED);
+			return;
+		} else if (v >= BASE_DISCONNECTED_MIN_MV &&
+			   v <= BASE_DISCONNECTED_MAX_MV) {
+			if (current_base_status == BASE_UNKNOWN) {
+				print_base_detect_value("disconnected", v);
+				base_detect_change(BASE_DISCONNECTED);
+			}
+			/* Still disconnected. */
+			return;
+		}
+	}
+
+retry:
+	print_base_detect_value("status unclear", v);
+	/* Unclear base status, schedule again in a while. */
+	hook_call_deferred(&base_detect_deferred_data,
+				   BASE_DETECT_RETRY_US);
+}
+
+void base_detect_interrupt(enum gpio_signal signal)
+{
+	uint64_t time_now = get_time().val;
+
+	if (base_detect_debounce_time <= time_now)
+		hook_call_deferred(&base_detect_deferred_data,
+				   BASE_DETECT_DEBOUNCE_US);
+
+	base_detect_debounce_time = time_now + BASE_DETECT_DEBOUNCE_US;
+}
+
+static void base_init(void)
+{
+	/*
+	 * Make sure base power and pull-down are off. This will reset the base
+	 * if it is already connected.
+	 */
+	gpio_set_level(GPIO_EN_PPVAR_VAR_BASE, 0);
+	gpio_set_level(GPIO_EN_CC_LID_BASE_PULLDN, 1);
+
+	/* Enable base detection interrupt. */
+	hook_call_deferred(&base_detect_deferred_data, BASE_DETECT_DEBOUNCE_US);
+	gpio_enable_interrupt(GPIO_CC_LID_BASE_ADC);
+}
+DECLARE_HOOK(HOOK_INIT, base_init, HOOK_PRIO_DEFAULT+1);
diff --git a/board/cheza/board.h b/board/cheza/board.h
index ab722c2aec..6c7ac79229 100644
--- a/board/cheza/board.h
+++ b/board/cheza/board.h
@@ -54,6 +54,9 @@
 #define CONFIG_LID_SWITCH
 #define CONFIG_EXTPOWER_GPIO
 
+#define CONFIG_TABLET_MODE
+#define CONFIG_TABLET_MODE_SWITCH
+
 /* Battery */
 #define CONFIG_BATTERY_CUT_OFF
 #define CONFIG_BATTERY_PRESENT_GPIO GPIO_BATT_PRES_ODL
@@ -183,6 +186,8 @@ int board_is_sourcing_vbus(int port);
 int board_vbus_sink_enable(int port, int enable);
 /* Reset all TCPCs. */
 void board_reset_pd_mcu(void);
+/* Base detection interrupt handler */
+void base_detect_interrupt(enum gpio_signal signal);
 
 #endif /* !defined(__ASSEMBLER__) */
 
diff --git a/board/cheza/build.mk b/board/cheza/build.mk
index 3958fb483e..2e8e53ec88 100644
--- a/board/cheza/build.mk
+++ b/board/cheza/build.mk
@@ -10,4 +10,4 @@ CHIP:=npcx
 CHIP_FAMILY:=npcx7
 CHIP_VARIANT:=npcx7m7wb
 
-board-y=battery.o board.o led.o usb_pd_policy.o
+board-y=battery.o board.o led.o usb_pd_policy.o base_detect.o
diff --git a/board/cheza/gpio.inc b/board/cheza/gpio.inc
index 707b51a850..d9e4aafb38 100644
--- a/board/cheza/gpio.inc
+++ b/board/cheza/gpio.inc
@@ -33,6 +33,7 @@ GPIO_INT(PS_HOLD,           PIN(D, 4), GPIO_INT_BOTH | GPIO_SEL_1P8V, power_sign
 GPIO_INT(PMIC_FAULT_L,      PIN(7, 6), GPIO_INT_BOTH | GPIO_SEL_1P8V, power_signal_interrupt)  /* Any PMIC fault? */
 GPIO_INT(POWER_GOOD,        PIN(5, 4), GPIO_INT_BOTH | GPIO_SEL_1P8V, power_signal_interrupt)  /* SRC_PP1800_S4A from PMIC */
 GPIO_INT(SHI_CS_L,          PIN(5, 3), GPIO_INT_FALLING | GPIO_PULL_DOWN | GPIO_SEL_1P8V, shi_cs_event)  /* AP_EC_SPI_CS_L */
+GPIO_INT(CC_LID_BASE_ADC,   PIN(4, 5), GPIO_INT_BOTH, base_detect_interrupt)  /* Base detection */
 
 GPIO(EC_SELF_RST,           PIN(E, 0), GPIO_OUT_LOW)   /* Self-reset EC */
 GPIO(EC_RST_ODL,            PIN(0, 2), GPIO_INPUT)     /* Wake source: EC reset */
@@ -148,7 +149,7 @@ ALTERNATE(PIN_MASK(9, 0x07), 1, MODULE_I2C, 0)             /* I2C1 SDA (GPIO90),
 ALTERNATE(PIN_MASK(8, 0x80), 1, MODULE_I2C, 0)             /* I2C1 SCL (GPIO87) */
 ALTERNATE(PIN_MASK(3, 0x48), 1, MODULE_I2C, 0)             /* I2C5 (GPIO33/36) */
 ALTERNATE(PIN_MASK(B, 0x0C), 1, MODULE_I2C, GPIO_SEL_1P8V) /* I2C7 (GPIOB2/B3) - 1.8V */
-ALTERNATE(PIN_MASK(4, 0x2C), 0, MODULE_ADC, 0)             /* ADC0 (GPIO45), ADC2 (GPIO43), ADC3 (GPIO42) */
+ALTERNATE(PIN_MASK(4, 0x0C), 0, MODULE_ADC, 0)             /* ADC2 (GPIO43), ADC3 (GPIO42) */
 ALTERNATE(PIN_MASK(4, 0xC0), 1, MODULE_SPI, GPIO_SEL_1P8V) /* SHI_SDO (GPIO47), SHI_SDI (GPIO46) */
 ALTERNATE(PIN_MASK(5, 0x28), 1, MODULE_SPI, GPIO_SEL_1P8V) /* SHI_SCLK (GPIO55), SHI_CS# (GPIO53) */
 ALTERNATE(PIN_MASK(B, 0x80), 1, MODULE_PWM, 0)             /* PWM5 (GPIOB7) */