linux-kernel - [PATCH 12/13] platform/chrome: cros_ec_lightbar - Add userspace lightbar control bit to EC

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Date:   Fri, 17 Mar 2017 14:57:53 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Olof Johansson <olof@...om.net>,
        Benson Leung <bleung@...omium.org>,
        Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Eric Caruso <ejcaruso@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: [PATCH 12/13] platform/chrome: cros_ec_lightbar - Add userspace lightbar control bit to EC

From: Eric Caruso <ejcaruso@...omium.org>

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@...omium.org>
Signed-off-by: Guenter Roeck <groeck@...omium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
---
 drivers/platform/chrome/cros_ec_lightbar.c | 38 ++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_lightbar.c b/drivers/platform/chrome/cros_ec_lightbar.c
index 4df379d..e570c1e 100644
--- a/drivers/platform/chrome/cros_ec_lightbar.c
+++ b/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,
 };
 
-- 
2.9.3