platform/chrome: cros_ec_lightbar - Add userspace lightbar control bit to EC

Some devices might want to turn off the lightbar if e.g. the
system turns the screen off due to idleness. This prevents the
kernel from going through its normal suspend/resume pathways.
Signed-off-by: Eric Caruso <ejcaruso@chromium.org>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Benson Leung <bleung@chromium.org>

drivers/platform/chrome/cros_ec_lightbar.c

@@ -38,6 +38,12 @@
 /* Rate-limit the lightbar interface to prevent DoS. */
 static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
 
+/*
+ * Whether or not we have given userspace control of the lightbar.
+ * If this is true, we won't do anything during suspend/resume.
+ */
+static bool userspace_control;
+
 static ssize_t interval_msec_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
@@ -407,11 +413,17 @@ int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
 
 int lb_suspend(struct cros_ec_dev *ec)
 {
+	if (userspace_control)
+		return 0;
+
 	return lb_send_empty_cmd(ec, LIGHTBAR_CMD_SUSPEND);
 }
 
 int lb_resume(struct cros_ec_dev *ec)
 {
+	if (userspace_control)
+		return 0;
+
 	return lb_send_empty_cmd(ec, LIGHTBAR_CMD_RESUME);
 }
 
@@ -528,6 +540,30 @@ static ssize_t program_store(struct device *dev, struct device_attribute *attr,
 	return ret;
 }
 
+static ssize_t userspace_control_show(struct device *dev,
+				      struct device_attribute *attr,
+				      char *buf)
+{
+	return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control);
+}
+
+static ssize_t userspace_control_store(struct device *dev,
+				       struct device_attribute *attr,
+				       const char *buf,
+				       size_t count)
+{
+	bool enable;
+	int ret;
+
+	ret = strtobool(buf, &enable);
+	if (ret < 0)
+		return ret;
+
+	userspace_control = enable;
+
+	return count;
+}
+
 /* Module initialization */
 
 static DEVICE_ATTR_RW(interval_msec);
@@ -536,6 +572,7 @@ static DEVICE_ATTR_WO(brightness);
 static DEVICE_ATTR_WO(led_rgb);
 static DEVICE_ATTR_RW(sequence);
 static DEVICE_ATTR_WO(program);
+static DEVICE_ATTR_RW(userspace_control);
 
 static struct attribute *__lb_cmds_attrs[] = {
 	&dev_attr_interval_msec.attr,
@@ -544,6 +581,7 @@ static struct attribute *__lb_cmds_attrs[] = {
 	&dev_attr_led_rgb.attr,
 	&dev_attr_sequence.attr,
 	&dev_attr_program.attr,
+	&dev_attr_userspace_control.attr,
 	NULL,
 };