[PATCH v2 7/8] platform/x86: huawei-wmi: add sysfs interface support

[Ayman Bagabas <ayman.bagabas@gmail.com>]

Battery charging thresholds and fn-lock are implemented as sysfs
attributes. Both have R/W permissions and set with root permission.
Although using Huawei Management Software in Windows gives access to
these features without admin privileges, user could use something like a
udev rule to change writing permissions of these attributes.

Signed-off-by: Ayman Bagabas <ayman.bagabas@gmail.com>
---
 drivers/platform/x86/huawei-wmi.c | 87 +++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/drivers/platform/x86/huawei-wmi.c b/drivers/platform/x86/huawei-wmi.c
index aac9b80f9976..cc6745ff1bad 100644
--- a/drivers/platform/x86/huawei-wmi.c
+++ b/drivers/platform/x86/huawei-wmi.c
@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
+#include <linux/sysfs.h>
 #include <linux/wmi.h>
 
 /*
@@ -388,6 +389,80 @@ static int huawei_wmi_fn_lock_set(struct device *dev, int on)
 	return huawei_wmi_cmd(dev, *(u64 *)arg, NULL, NULL);
 }
 
+/* sysfs */
+
+static ssize_t charge_thresholds_show(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int err, low, high;
+
+	err = huawei_wmi_battery_get(dev, &low, &high);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%d %d\n", low, high);
+}
+
+static ssize_t charge_thresholds_store(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t size)
+{
+	int low, high, err;
+
+	if (sscanf(buf, "%d %d", &low, &high) != 2 ||
+			low < 0 || high > 100 ||
+			low > high)
+		return -EINVAL;
+
+	err = huawei_wmi_battery_set(dev, low, high);
+	if (err)
+		return err;
+
+	return size;
+}
+
+static ssize_t fn_lock_state_show(struct device *dev,
+		struct device_attribute *attr,
+		char *buf)
+{
+	int err, on;
+
+	err = huawei_wmi_fn_lock_get(dev, &on);
+	if (err)
+		return err;
+
+	return sprintf(buf, "%d\n", on);
+}
+
+static ssize_t fn_lock_state_store(struct device *dev,
+		struct device_attribute *attr,
+		const char *buf, size_t size)
+{
+	int on, err;
+
+	if (kstrtoint(buf, 10, &on) ||
+			on < 0 || on > 1)
+		return -EINVAL;
+
+	err = huawei_wmi_fn_lock_set(dev, on);
+	if (err)
+		return err;
+
+	return size;
+}
+
+static DEVICE_ATTR_RW(charge_thresholds);
+static DEVICE_ATTR_RW(fn_lock_state);
+
+static struct attribute *huawei_wmi_attrs[] = {
+	&dev_attr_charge_thresholds.attr,
+	&dev_attr_fn_lock_state.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(huawei_wmi);
+
 /* Input */
 
 static void huawei_wmi_process_key(struct input_dev *idev, int code)
@@ -509,8 +584,16 @@ 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 = sysfs_create_group(&pdev->dev.kobj, &huawei_wmi_group);
+		if (err) {
+			dev_err(&pdev->dev, "Failed to create sysfs interface\n");
+			return err;
+		}
+
 		err = huawei_wmi_leds_setup(&pdev->dev);
 		if (err)
 			dev_err(&pdev->dev, "Failed to setup leds\n");
@@ -526,6 +609,10 @@ static int huawei_wmi_remove(struct platform_device *pdev)
 	if (wmi_has_guid(HWMI_EVENT_GUID))
 		wmi_remove_notify_handler(HWMI_EVENT_GUID);
 
+	if (wmi_has_guid(HWMI_METHOD_GUID)) {
+		sysfs_remove_group(&pdev->dev.kobj, &huawei_wmi_group);
+	}
+
 	return 0;
 }
 
-- 
2.20.1