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Subject[PATCH V2] cros_ec: Expose sysfile to force battery cut-off on shutdown.
Date
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 <ravisadineni@chromium.org>
---
V2: Use kstrtobool() instead of kstrtou8() and add documentation.

.../ABI/testing/sysfs-class-chromeos | 8 ++++
drivers/platform/chrome/cros_ec_sysfs.c | 37 +++++++++++++++++++
2 files changed, 45 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..44d3cee6e7ae
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-chromeos
@@ -0,0 +1,8 @@
+What: /sys/class/chromeos/cros_ec/cutoff_at_shutdown
+Date: February 2019
+Contact: Ravi Chandra Sadineni <ravisadineni@chromium.org>
+Description:
+ On writing '[Yy1]' to cutoff_at_shutdown property,
+ kernel sends a host command to EC requesting battery
+ cutoff on next shutdown. If AC is plugged in before
+ next shutdown, EC resets this flag.
diff --git a/drivers/platform/chrome/cros_ec_sysfs.c b/drivers/platform/chrome/cros_ec_sysfs.c
index f34a50121064..f5168ce8bfc7 100644
--- a/drivers/platform/chrome/cros_ec_sysfs.c
+++ b/drivers/platform/chrome/cros_ec_sysfs.c
@@ -322,14 +322,51 @@ static ssize_t kb_wake_angle_store(struct device *dev,
return count;
}

+/* Battery cut-off control */
+static ssize_t cutoff_at_shutdown_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);
+ bool cutoff_battery;
+
+ if (kstrtobool(buf, &cutoff_battery))
+ return -EINVAL;
+
+ if (!cutoff_battery)
+ return count;
+
+ 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;
+ param->flags = EC_BATTERY_CUTOFF_FLAG_AT_SHUTDOWN;
+ msg->outsize = sizeof(*param);
+ msg->insize = 0;
+ 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);
+static DEVICE_ATTR_WO(cutoff_at_shutdown);

static struct attribute *__ec_attrs[] = {
+ &dev_attr_cutoff_battery_at_shutdown.attr,
&dev_attr_kb_wake_angle.attr,
&dev_attr_reboot.attr,
&dev_attr_version.attr,
--
2.20.1
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