[PATCH v2 5/8] platform/x86: huawei-wmi: add battery charging protection support

[Ayman Bagabas <ayman.bagabas@xxxxxxxxx>]

Some models that implement the new WMI management interface can control
battery charging thresholds where it limits charging the battery once it
reaches certain thresholds. This feature is not present in MateBook X
(2017).

Signed-off-by: Ayman Bagabas <ayman.bagabas@xxxxxxxxx>
---
 drivers/platform/x86/huawei-wmi.c | 56 +++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/platform/x86/huawei-wmi.c b/drivers/platform/x86/huawei-wmi.c
index 358d9d168300..06d83e613504 100644
--- a/drivers/platform/x86/huawei-wmi.c
+++ b/drivers/platform/x86/huawei-wmi.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/delay.h>
 #include <linux/dmi.h>
 #include <linux/input.h>
 #include <linux/input/sparse-keymap.h>
@@ -48,6 +49,7 @@ struct huawei_wmi {
 	struct led_classdev cdev;
 	struct input_dev *idev[2];
 	struct mutex wmi_lock;
+	struct mutex battery_lock;
 	struct platform_device *pdev;
 };
 
@@ -302,6 +304,59 @@ static int huawei_wmi_leds_setup(struct device *dev)
 	return devm_led_classdev_register(dev, &huawei->cdev);
 }
 
+/* Battery protection */
+
+static int huawei_wmi_battery_get(struct device *dev, int *low, int *high)
+{
+	struct huawei_wmi *huawei = dev_get_drvdata(dev);
+	u8 ret[0x100];
+	int err, i;
+
+	mutex_lock(&huawei->battery_lock);
+	err = huawei_wmi_cmd(dev, BATTERY_THRESH_GET, ret, 0x100);
+	mutex_unlock(&huawei->battery_lock);
+	if (err) {
+		return err;
+	}
+
+	/* Find the last two non-zero values. Return status is ignored. */
+	i = 0x100;
+	do {
+		*low = ret[i-1];
+		*high = ret[i];
+	} while (i > 2 && !ret[i--]);
+
+	return 0;
+}
+
+static int huawei_wmi_battery_set(struct device *dev, int low, int high)
+{
+	struct huawei_wmi *huawei = dev_get_drvdata(dev);
+	u8 arg[8];
+	int err;
+
+	*(u64 *)arg = BATTERY_THRESH_SET;
+	arg[2] = low;
+	arg[3] = high;
+
+	/* This is an edge case were some models turn battery protection
+	 * off without changing their thresholds values. We clear the
+	 * values before turning off protection. Sometimes we need a sleep delay to
+	 * make sure these values make their way to EC memory.
+	 */
+	if (low == 0 && high == 100) {
+		huawei_wmi_battery_set(dev, 0, 0);
+	}
+
+	mutex_lock(&huawei->battery_lock);
+	err = huawei_wmi_cmd(dev, *(u64 *)arg, NULL, NULL);
+	if (quirks && quirks->battery_sleep)
+		msleep(1000);
+	mutex_unlock(&huawei->battery_lock);
+
+	return err;
+}
+
 /* Input */
 
 static void huawei_wmi_process_key(struct input_dev *idev, int code)
@@ -424,6 +479,7 @@ static int huawei_wmi_probe(struct platform_device *pdev)
 
 	if (wmi_has_guid(HWMI_METHOD_GUID)) {
 		mutex_init(&huawei->wmi_lock);
+		mutex_init(&huawei->battery_lock);
 		err = huawei_wmi_leds_setup(&pdev->dev);
 		if (err)
 			dev_err(&pdev->dev, "Failed to setup leds\n");
-- 
2.20.1