google-smblite-hvdcp: Runtime-enable HVDCP (QC3.0) negotiation

- Add 'enabled' sysfs node to gate HVDCP negotiation at runtime.
  Default is 0 (disabled). Write 1 to the node to enable.
- For an HVDCP request, the state machine will now first transition to
  a READY state. When in READY, the state machine will start
  negotiation only if enabled is set.

Bug: 319005242
Signed-off-by: Andrei Ciubotariu <aciubotariu@google.com>
(cherry picked from https://partner-android-review.googlesource.com/q/commit:7d418969964edbc0ca6aceaf133b6c21b577c36c)
(cherry picked from https://partner-android-review.googlesource.com/q/commit:62f5509d09c84eafcc101dac64596a332fbcfaeb)
Merged-In: I89933873cc50a3b1fe2617ff96a05ba78df6fed6
Change-Id: I89933873cc50a3b1fe2617ff96a05ba78df6fed6

1 files changed, 63 insertions, 1 deletions

diff --git a/drivers/power/supply/google/google-smblite-hvdcp.c b/drivers/power/supply/google/google-smblite-hvdcp.c
index 558d5c8..4a3fabf 100644
--- a/drivers/power/supply/google/google-smblite-hvdcp.c
+++ b/drivers/power/supply/google/google-smblite-hvdcp.c
@@ -5,7 +5,9 @@
 Controller state transitions illustrated below in graphviz format:
 
 	digraph {
-		OFF -> USBIN_SUSPEND_WAIT [label="HVDCP request"]
+		OFF -> READY [label="HVDCP request received"]
+		READY -> USBIN_SUSPEND_WAIT [label="HVDCP functionality enabled"]
+		READY -> OFF [label="unplug"]
 
 		USBIN_SUSPEND_WAIT -> ENTER_IDLE_WAIT [label="usbin suspended"]
 
@@ -67,6 +69,7 @@ Controller state transitions illustrated below in graphviz format:
 
 #define STATES \
 	X(OFF) \
+	X(READY) \
 	X(PAUSE) \
 	X(USBIN_SUSPEND_WAIT) \
 	X(ENTER_IDLE_WAIT) \
@@ -157,6 +160,7 @@ struct hvdcp {
 	u16 settle_monitor_ms;
 	u32 voltage_ceiling;
 	u32 abandon_timeout_ms;
+	bool enabled;
 	struct device *dev;
 	struct power_supply *shim_psy;
 	struct smblite_shim *smblite_shim;
@@ -479,6 +483,18 @@ rerun_controller:
 
 	switch (hvdcp->state) {
 	case HVDCP_OFF:
+		new_state = HVDCP_READY;
+		wait_ms = 0;
+		break;
+	case HVDCP_READY:
+		if (!hvdcp->enabled) {
+			/*
+			 * Nothing to do if functionality is disabled, park
+			 * here in case functionality gets enabled.
+			 */
+			wait_ms = WAIT_DISABLED;
+			break;
+		}
 		/*
 		 * Suspend the charging path so that:
 		 *   - We can read an accurate charger voltage without drops due
@@ -726,11 +742,57 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 }
 static const DEVICE_ATTR_RO(state);
 
+static ssize_t enabled_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	bool enabled;
+	struct platform_device *pdev =
+		container_of(dev, struct platform_device, dev);
+	struct hvdcp *hvdcp = platform_get_drvdata(pdev);
+
+	mutex_lock(&hvdcp->lock);
+	enabled = hvdcp->enabled;
+	mutex_unlock(&hvdcp->lock);
+
+	return scnprintf(buf, PAGE_SIZE, "%u\n", (int)enabled);
+}
+
+static ssize_t enabled_store(struct device *dev,
+			struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	bool enable;
+	int ret;
+	struct platform_device *pdev =
+	container_of(dev, struct platform_device, dev);
+	struct hvdcp *hvdcp = platform_get_drvdata(pdev);
+
+	ret = kstrtobool(buf, &enable);
+	if (ret != 0)
+		return ret;
+
+	mutex_lock(&hvdcp->lock);
+	hvdcp->enabled = enable;
+	if (hvdcp->state == HVDCP_READY)
+		queue_work(hvdcp->controller_q, &hvdcp->controller_work);
+	mutex_unlock(&hvdcp->lock);
+
+	return count;
+}
+static const DEVICE_ATTR_RW(enabled);
+
 static int setup_sysfs(struct hvdcp *hvdcp)
 {
 	struct device *dev = hvdcp->dev;
 	int ret;
 
+	ret = device_create_file(hvdcp->dev, &dev_attr_enabled);
+	if (ret < 0) {
+		dev_err(dev, "Failed to create %s: %d\n",
+			dev_attr_enabled.attr.name, ret);
+		return ret;
+	}
+
 	ret = device_create_file(hvdcp->dev, &dev_attr_state);
 	if (ret < 0) {
 		dev_err(dev, "Failed to create %s: %d\n",