[PATCH v5 5/6] platform/x86: huawei-wmi: Add fn-lock support

[Ayman Bagabas]

Huawei Matebook laptops uses Fn key and toggle to access F1-F12 keys.
Along with that, there is this feature called fn-lock that inverts the
behavior of this Fn key and the F1-F12 row.

Signed-off-by: Ayman Bagabas <ayman.baga...@gmail.com>
---
 drivers/platform/x86/huawei-wmi.c | 85 +++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)

diff --git a/drivers/platform/x86/huawei-wmi.c 
b/drivers/platform/x86/huawei-wmi.c
index 6e791f9ffc26..d550c63fcba7 100644
--- a/drivers/platform/x86/huawei-wmi.c
+++ b/drivers/platform/x86/huawei-wmi.c
@@ -54,6 +54,7 @@ static struct quirk_entry *quirks;
 
 struct huawei_wmi {
        bool battery_available;
+       bool fn_lock_available;
 
        struct input_dev *idev[2];
        struct led_classdev cdev;
@@ -509,6 +510,88 @@ static void huawei_wmi_battery_exit(struct device *dev)
        }
 }
 
+/* Fn lock */
+
+static int huawei_wmi_fn_lock_get(int *on)
+{
+       u8 ret[0x100] = { 0 };
+       int err, i;
+
+       err = huawei_wmi_cmd(FN_LOCK_GET, ret, 0x100);
+       if (err)
+               return err;
+
+       /* Find the first non-zero value. Return status is ignored. */
+       i = 1;
+       do {
+               if (on)
+                       *on = ret[i] - 1; // -1 undefined, 0 off, 1 on.
+       } while (i < 0xff && !ret[i++]);
+
+       return 0;
+}
+
+static int huawei_wmi_fn_lock_set(int on)
+{
+       union hwmi_arg arg;
+
+       arg.cmd = FN_LOCK_SET;
+       arg.args[2] = on + 1; // 0 undefined, 1 off, 2 on.
+
+       return huawei_wmi_cmd(arg.cmd, NULL, 0);
+}
+
+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(&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(on);
+       if (err)
+               return err;
+
+       return size;
+}
+
+static DEVICE_ATTR_RW(fn_lock_state);
+
+static void huawei_wmi_fn_lock_setup(struct device *dev)
+{
+       struct huawei_wmi *huawei = dev_get_drvdata(dev);
+
+       huawei->fn_lock_available = true;
+       if (huawei_wmi_fn_lock_get(NULL)) {
+               huawei->fn_lock_available = false;
+               return;
+       }
+
+       device_create_file(dev, &dev_attr_fn_lock_state);
+}
+
+static void huawei_wmi_fn_lock_exit(struct device *dev)
+{
+       if (huawei_wmi->fn_lock_available)
+               device_remove_file(dev, &dev_attr_fn_lock_state);
+}
+
 /* Input */
 
 static void huawei_wmi_process_key(struct input_dev *idev, int code)
@@ -632,6 +715,7 @@ static int huawei_wmi_probe(struct platform_device *pdev)
                mutex_init(&huawei_wmi->battery_lock);
 
                huawei_wmi_leds_setup(&pdev->dev);
+               huawei_wmi_fn_lock_setup(&pdev->dev);
                huawei_wmi_battery_setup(&pdev->dev);
        }
 
@@ -651,6 +735,7 @@ static int huawei_wmi_remove(struct platform_device *pdev)
 
        if (wmi_has_guid(HWMI_METHOD_GUID)) {
                huawei_wmi_battery_exit(&pdev->dev);
+               huawei_wmi_fn_lock_exit(&pdev->dev);
        }
 
        return 0;
-- 
2.21.0