power: Add task-safe API to control 5V rail.

For certain cannonlake designs, the 5V rail can be controlled by both
the chipset task as well as other tasks such as the USB charger tasks to
perform BC1.2 detection.  This commit introduces an API that allows the
tasks to enable/disable the 5V rail.  Enable requests will immediately
enable the rail, however, attempting to disable the rail will only
result in a request.  Once all tasks want to turn off the 5V rail, the
rail will be turned off.

A bitmask is introduced to keep track of the requests.  Index 0 is for
the chipset task.

All of this is gated behind a config option:

  CONFIG_POWER_PP5000_CONTROL

BUG=b:65991615
BRANCH=None
TEST=With other zoombini code, verify that 5V can be enabled and disabled.

Change-Id: I1722b4a272c4d6ee24408929f5a7402051bb9cf3
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/722322
Commit-Ready: Aseda Aboagye <aaboagye@chromium.org>
Tested-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Shawn N <shawnn@chromium.org>

4 files changed, 54 insertions, 0 deletions

diff --git a/include/config.h b/include/config.h
index fefeaaf81d..8156ead7f4 100644
--- a/include/config.h
+++ b/include/config.h
@@ -1970,6 +1970,9 @@
 /* Disable the power-on transition when the lid is opened */
 #undef CONFIG_POWER_IGNORE_LID_OPEN
 
+/* Enable a task-safe way to control the PP5000 rail. */
+#undef CONFIG_POWER_PP5000_CONTROL
+
 /* Support stopping in S5 on shutdown */
 #undef CONFIG_POWER_SHUTDOWN_PAUSE_IN_S5
 
diff --git a/include/power.h b/include/power.h
index 52316628fd..20b2ee6cf6 100644
--- a/include/power.h
+++ b/include/power.h
@@ -10,6 +10,7 @@
 
 #include "common.h"
 #include "gpio.h"
+#include "task_id.h"
 
 enum power_state {
 	/* Steady states */
@@ -209,4 +210,18 @@ void power_reset_host_sleep_state(enum host_sleep_event sleep_event);
 #endif /* CONFIG_POWER_S0IX */
 #endif /* CONFIG_POWER_TRACK_HOST_SLEEP_STATE */
 
+/**
+ * Enable/Disable the PP5000 rail.
+ *
+ * This function will turn on the 5V rail immediately if requested.  However,
+ * the rail will not turn off until all tasks want it off.
+ *
+ * NOTE: Be careful when calling from deferred functions, as they will all be
+ * executed within the same task context! (The HOOKS task).
+ *
+ * @param tid: The caller's task ID.
+ * @param enable: 1 to turn on the rail, 0 to request the rail to be turned off.
+ */
+void power_5v_enable(task_id_t tid, int enable);
+
 #endif  /* __CROS_EC_POWER_H */
diff --git a/power/cannonlake.c b/power/cannonlake.c
index 535010c103..270eba5f35 100644
--- a/power/cannonlake.c
+++ b/power/cannonlake.c
@@ -12,6 +12,7 @@
 #include "intel_x86.h"
 #include "power.h"
 #include "power_button.h"
+#include "task.h"
 #include "timer.h"
 
 /* Console output macros */
@@ -104,11 +105,19 @@ enum power_state power_handle_state(enum power_state state)
 		 * In S3, enable 5V rail.  Wireless rails are handled by common
 		 * x86 chipset code.
 		 */
+#ifdef CONFIG_POWER_PP5000_CONTROL
+		power_5v_enable(task_get_current(), 1);
+#else
 		gpio_set_level(GPIO_EN_PP5000, 1);
+#endif
 		break;
 
 	case POWER_S3S5:
+#ifdef CONFIG_POWER_PP5000_CONTROL
+		power_5v_enable(task_get_current(), 0);
+#else
 		gpio_set_level(GPIO_EN_PP5000, 0);
+#endif
 		break;
 
 	default:
diff --git a/power/common.c b/power/common.c
index 0a32bb13e1..467f41e9aa 100644
--- a/power/common.c
+++ b/power/common.c
@@ -782,3 +782,30 @@ void power_reset_host_sleep_state(enum host_sleep_event sleep_event)
 #endif /* CONFIG_POWER_S0IX */
 
 #endif /* CONFIG_POWER_TRACK_HOST_SLEEP_STATE */
+
+#ifdef CONFIG_POWER_PP5000_CONTROL
+/* 5V enable request bitmask from various tasks. */
+static uint32_t pwr_5v_en_req;
+static struct mutex pwr_5v_ctl_mtx;
+
+void __attribute__((weak)) power_5v_enable(task_id_t tid, int enable)
+{
+	mutex_lock(&pwr_5v_ctl_mtx);
+
+	if (enable) /* Set the bit indicating the request. */
+		pwr_5v_en_req |= 1 << tid;
+	else /* Clear the task's request bit. */
+		pwr_5v_en_req &= ~(1 << tid);
+
+	/*
+	 * If there are any outstanding requests for the rail to be enabled,
+	 * turn on the rail.  Otherwise, turn it off.
+	 */
+	if (pwr_5v_en_req)
+		gpio_set_level(GPIO_EN_PP5000, 1);
+	else
+		gpio_set_level(GPIO_EN_PP5000, 0);
+
+	mutex_unlock(&pwr_5v_ctl_mtx);
+}
+#endif /* defined(CONFIG_POWER_PP5000_CONTROL) */