On chromebooks, power_manager daemon normally shutsdown(S5) the device
when the battery charge falls below 4% threshold. Chromeos EC then
normally spends an hour in S5 before hibernating. If the battery charge
falls below critical threshold in the mean time, EC does a battery cutoff
instead of hibernating. On some chromebooks, S5 is optimal enough
resulting in EC hibernating without battery cut-off. This results in
battery deep-discharging. This is a bad user experience as battery
has to trickle charge before booting when the A.C is plugged in the next
time.
This patch exposes a sysfs file for an userland daemon to suggest EC if it
has to do a battery cut-off instead of hibernating when the system enters
S5 next time.
Signed-off-by: RaviChandra Sadineni <ravisadin...@chromium.org>
---
V3: Make battery-cutoff generic and expose 'at-shutdown' flag.
V2: Use kstrtobool() instead of kstrtou8() and add documentation.
.../ABI/testing/sysfs-class-chromeos | 10 ++++
drivers/platform/chrome/cros_ec_sysfs.c | 48 +++++++++++++++++++
2 files changed, 58 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-chromeos
diff --git a/Documentation/ABI/testing/sysfs-class-chromeos
b/Documentation/ABI/testing/sysfs-class-chromeos
new file mode 100644
index 000000000000..d5ab22c44977
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-chromeos
@@ -0,0 +1,10 @@
+What: /sys/class/chromeos/cros_ec/battery-cuttoff
+Date: February 2019
+Contact: Ravi Chandra Sadineni <ravisadin...@chromium.org>
+Description:
+ cros_ec battery cuttoff configuration. Only option
+ currently exposed is 'at-shutdown'.
+
+ 'at-shutdown' sends a host command to EC requesting
+ battery cutoff on next shutdown. If AC is plugged
+ in before next shutdown, EC ignores the request.
diff --git a/drivers/platform/chrome/cros_ec_sysfs.c
b/drivers/platform/chrome/cros_ec_sysfs.c
index f34a50121064..6ef6b860c818 100644
--- a/drivers/platform/chrome/cros_ec_sysfs.c
+++ b/drivers/platform/chrome/cros_ec_sysfs.c
@@ -322,14 +322,62 @@ static ssize_t kb_wake_angle_store(struct device *dev,
return count;
}
+/* Battery cut-off control */
+static ssize_t battery_cutoff_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct ec_params_battery_cutoff *param;
+ struct cros_ec_command *msg;
+ int ret;
+ struct cros_ec_dev *ec =
+ container_of(dev, struct cros_ec_dev, class_dev);
+ char *p;
+ int len;
+
+ msg = kmalloc(sizeof(*msg) + EC_HOST_PARAM_SIZE, GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ param = (struct ec_params_battery_cutoff *)msg->data;
+ msg->command = EC_CMD_BATTERY_CUT_OFF + ec->cmd_offset;
+ msg->version = 1;
+ msg->outsize = sizeof(*param);
+ msg->insize = 0;
+
+ p = memchr(buf, '\n', count);
+ len = p ? p - buf : count;
+
+ if (len == 11 && !strncmp(buf, "at-shutdown", len)) {
+ param->flags = EC_BATTERY_CUTOFF_FLAG_AT_SHUTDOWN;
+ } else {
+ kfree(msg);
+ return -EINVAL;
+ }
+
+ ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
+ kfree(msg);
+ if (ret < 0)
+ return ret;
+ return count;
+}
+
/* Module initialization */
static DEVICE_ATTR_RW(reboot);
static DEVICE_ATTR_RO(version);
static DEVICE_ATTR_RO(flashinfo);
static DEVICE_ATTR_RW(kb_wake_angle);
+/*
+ * Currently EC does not expose a host command to read the status of
+ * battery cut-off configuration. Also there is no requirement to read
+ * the status of these flags from userland. So marking this attribute as
+ * write-only.
+ */
+static DEVICE_ATTR_WO(battery_cutoff);
static struct attribute *__ec_attrs[] = {
+ &dev_attr_battery_cutoff.attr,
&dev_attr_kb_wake_angle.attr,
&dev_attr_reboot.attr,
&dev_attr_version.attr,
--
2.20.1
