stm32l: supports fake-hibernate

We don't have available GPIO pin for power button as the hibernate
(stand-by) wake-up source. Also, we don't want to do board change.

So, put the EC in a decent infinite loop to pretend the hibernate mode
and wait for particular wake-up event. This should be fine because
the AP is already down before EC hibernates.

BUG=chrome-os-partner:25435
BRANCH=Nyan
TEST=see comment #6 of issue for detailed test steps.

Change-Id: I2cae131789f9ca5808b60d5f2495222ca9016e7c
Signed-off-by: Louis Yung-Chieh Lo <yjlou@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/186061
Reviewed-by: Randall Spangler <rspangler@chromium.org>

6 files changed, 139 insertions, 5 deletions

diff --git a/chip/stm32/clock-stm32l.c b/chip/stm32/clock-stm32l.c
index b2de4e8073..2f1b0f655a 100644
--- a/chip/stm32/clock-stm32l.c
+++ b/chip/stm32/clock-stm32l.c
@@ -14,6 +14,18 @@
 #include "registers.h"
 #include "util.h"
 
+#ifdef CONFIG_STM32L_FAKE_HIBERNATE
+#include "extpower.h"
+#include "keyboard_config.h"
+#include "lid_switch.h"
+#include "power.h"
+#include "power_button.h"
+#include "system.h"
+#include "task.h"
+
+static int fake_hibernate;
+#endif
+
 /* High-speed oscillator is 16 MHz */
 #define HSI_CLOCK 16000000
 /*
@@ -159,6 +171,113 @@ void clock_enable_module(enum module_id module, int enable)
 	clock_mask = new_mask;
 }
 
+#ifdef CONFIG_STM32L_FAKE_HIBERNATE
+/*
+ *  This is for NOT having enough hibernate (more precisely, the stand-by mode)
+ *  wake-up source pin. STM32L100 supports 3 wake-up source pins:
+ *
+ *     WKUP1 (PA0)  -- used for ACOK_PMU
+ *     WKUP2 (PC13) -- used for LID_OPEN
+ *     WKUP3 (PE6)  -- cannot be used due to IC package.
+ *
+ *  However, we need the power button as a wake-up source as well and there is
+ *  no available pin for us (we don't want to move the ACOK_PMU pin).
+ *
+ *  Fortunately, the STM32L is low-power enough so that we don't need the
+ *  super-low-power mode. So, we fake this hibernate mode and accept the
+ *  following wake-up source.
+ *
+ *     RTC alarm  (faked as well).
+ *     Power button
+ *     Lid open
+ *     AC detected
+ *
+ *  The original issue is here: crosbug.com/p/25435.
+ */
+void __enter_hibernate(uint32_t seconds, uint32_t microseconds)
+{
+	int i;
+	fake_hibernate = 1;
+
+#ifdef CONFIG_POWER_COMMON
+	/*
+	 * A quick hack to stop annoying messages from charger task.
+	 *
+	 * When the battery is under 3%, the power task would call
+	 * power_off() to shutdown AP. However, the power_off() would
+	 * notify the HOOK_CHIPSET_SHUTDOWN, where the last hook is
+	 * charge_shutdown() and it hibernates the power task (infinite
+	 * loop -- not real CPU hibernate mode). Unfortunately, the
+	 * charger task is still running. It keeps generating annoying
+	 * log message.
+	 *
+	 * Thus, the hack is to set the power state machine (before we
+	 * enter infinite loop) so that the charger task thinks the AP
+	 * is off and stops generating messages.
+	 */
+	power_set_state(POWER_G3);
+#endif
+
+	/*
+	 * Change keyboard outputs to high-Z to reduce power draw.
+	 * We don't need corresponding code to change them back,
+	 * because fake hibernate is always exited with a reboot.
+	 *
+	 * A little hacky to do this here.
+	 */
+	for (i = GPIO_KB_OUT00; i < GPIO_KB_OUT00 + KEYBOARD_COLS; i++)
+		gpio_set_flags(i, GPIO_INPUT);
+
+	ccprintf("[%T fake hibernate. waits for power button/lid/RTC/AC]\n");
+	cflush();
+
+	if (seconds || microseconds) {
+		if (seconds)
+			sleep(seconds);
+		if (microseconds)
+			usleep(microseconds);
+	} else {
+		while (1)
+			task_wait_event(-1);
+	}
+
+	ccprintf("[%T fake RTC alarm fires. resets EC]\n");
+	cflush();
+	system_reset(SYSTEM_RESET_HARD);
+}
+
+static void fake_hibernate_power_button_hook(void)
+{
+	if (fake_hibernate && lid_is_open() && !power_button_is_pressed()) {
+		ccprintf("[%T %s() resets EC]\n", __func__);
+		cflush();
+		system_reset(SYSTEM_RESET_HARD);
+	}
+}
+DECLARE_HOOK(HOOK_POWER_BUTTON_CHANGE, fake_hibernate_power_button_hook,
+	HOOK_PRIO_DEFAULT);
+
+static void fake_hibernate_lid_hook(void)
+{
+	if (fake_hibernate && lid_is_open()) {
+		ccprintf("[%T %s() resets EC]\n", __func__);
+		cflush();
+		system_reset(SYSTEM_RESET_HARD);
+	}
+}
+DECLARE_HOOK(HOOK_LID_CHANGE, fake_hibernate_lid_hook, HOOK_PRIO_DEFAULT);
+
+static void fake_hibernate_ac_hook(void)
+{
+	if (fake_hibernate && extpower_is_present()) {
+		ccprintf("[%T %s() resets EC]\n", __func__);
+		cflush();
+		system_reset(SYSTEM_RESET_HARD);
+	}
+}
+DECLARE_HOOK(HOOK_AC_CHANGE, fake_hibernate_ac_hook, HOOK_PRIO_DEFAULT);
+#endif
+
 void clock_init(void)
 {
 	/*
diff --git a/chip/stm32/config-stm32l100.h b/chip/stm32/config-stm32l100.h
index a79bd2282e..1d18b6c5e8 100644
--- a/chip/stm32/config-stm32l100.h
+++ b/chip/stm32/config-stm32l100.h
@@ -51,3 +51,6 @@
 
 /* Use DMA for UART receive */
 #define CONFIG_UART_RX_DMA
+
+/* Fake hibernate mode */
+#define CONFIG_STM32L_FAKE_HIBERNATE
diff --git a/include/config.h b/include/config.h
index a8e52f5c7b..76deccc7e4 100644
--- a/include/config.h
+++ b/include/config.h
@@ -665,6 +665,9 @@
 /* Default stack size to use for tasks, in bytes */
 #undef CONFIG_STACK_SIZE
 
+/* Fake hibernate mode */
+#undef CONFIG_STM32L_FAKE_HIBERNATE
+
 /*
  * Compile common code to handle simple switch inputs such as the recovery
  * button input from the servo debug interface.
diff --git a/include/power.h b/include/power.h
index 5469ffad3f..36054e8bd1 100644
--- a/include/power.h
+++ b/include/power.h
@@ -73,6 +73,13 @@ int power_has_signals(uint32_t want);
 int power_wait_signals(uint32_t want);
 
 /**
+ * Set the low-level power chipset state.
+ *
+ * @param new_state New chipset state.
+ */
+void power_set_state(enum power_state new_state);
+
+/**
  * Chipset-specific initialization
  *
  * @return The state the chipset should start in.  Usually POWER_G3, but may
diff --git a/power/common.c b/power/common.c
index 3a92780bf4..816ab50716 100644
--- a/power/common.c
+++ b/power/common.c
@@ -114,11 +114,6 @@ int power_wait_signals(uint32_t want)
 	return EC_SUCCESS;
 }
 
-/**
- * Set the low-level power chipset state.
- *
- * @param new_state	New chipset state.
- */
 void power_set_state(enum power_state new_state)
 {
 	/* Record the time we go into G3 */
diff --git a/power/tegra.c b/power/tegra.c
index 021626ee93..4ca3a172f3 100644
--- a/power/tegra.c
+++ b/power/tegra.c
@@ -318,6 +318,10 @@ static void power_on(void)
 {
 	uint64_t t;
 
+	/* Set pull-up and enable interrupt */
+	gpio_set_flags(GPIO_SUSPEND_L, GPIO_INPUT | GPIO_PULL_UP |
+		GPIO_INT_BOTH);
+
 	/* Make sure we de-assert the PMI_THERM_L and AP_RESET_L pin. */
 	set_pmic_therm(0);
 	set_ap_reset(0);
@@ -390,6 +394,9 @@ static void power_off(void)
 	/* switch off all rails */
 	chipset_force_shutdown();
 
+	/* Change SUSPEND_L pin to high-Z to reduce power draw. */
+	gpio_set_flags(GPIO_SUSPEND_L, GPIO_INPUT);
+
 	lid_opened = 0;
 	enable_sleep(SLEEP_MASK_AP_RUN);
 	powerled_set_state(POWERLED_STATE_OFF);