Huawei Matebook laptops come with a WMI management interface that can
control various aspects of the device. This interface is also found on
the old Matebook X released in 2017.

Use that to control the mic mute LED.

Signed-off-by: Ayman Bagabas <ayman.baga...@gmail.com>
---
 drivers/platform/x86/huawei-wmi.c | 217 +++++++++++++++++++++++++-----
 1 file changed, 180 insertions(+), 37 deletions(-)

diff --git a/drivers/platform/x86/huawei-wmi.c 
b/drivers/platform/x86/huawei-wmi.c
index 0e919bf56ad1..41904b1cc284 100644
--- a/drivers/platform/x86/huawei-wmi.c
+++ b/drivers/platform/x86/huawei-wmi.c
@@ -11,18 +11,35 @@
 #include <linux/input/sparse-keymap.h>
 #include <linux/leds.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/wmi.h>
 
 /*
  * Huawei WMI GUIDs
  */
+#define HWMI_METHOD_GUID "ABBC0F5B-8EA1-11D1-A000-C90629100000"
 #define HWMI_EVENT_GUID "ABBC0F5C-8EA1-11D1-A000-C90629100000"
 
 /* Legacy GUIDs */
 #define WMI0_EXPENSIVE_GUID "39142400-C6A3-40fa-BADB-8A2652834100"
 #define WMI0_EVENT_GUID "59142400-C6A3-40fa-BADB-8A2652834100"
 
+/* HWMI commands */
+
+enum {
+       BATTERY_THRESH_GET              = 0x00001103, /* \GBTT */
+       BATTERY_THRESH_SET              = 0x00001003, /* \SBTT */
+       FN_LOCK_GET                     = 0x00000604, /* \GFRS */
+       FN_LOCK_SET                     = 0x00000704, /* \SFRS */
+       MICMUTE_LED_SET                 = 0x00000b04, /* \SMLS */
+};
+
+union hwmi_arg {
+       u64 cmd;
+       u8 args[8];
+};
+
 struct quirk_entry {
        bool battery_reset;
        bool ec_micmute;
@@ -35,8 +52,8 @@ struct huawei_wmi {
        struct input_dev *idev[2];
        struct led_classdev cdev;
        struct platform_device *pdev;
-       acpi_handle handle;
-       char *acpi_method;
+
+       struct mutex wmi_lock;
 };
 
 struct huawei_wmi *huawei_wmi;
@@ -110,52 +127,168 @@ static const struct dmi_system_id huawei_quirks[] = {
        {  }
 };
 
+/* Utils */
+
+static int huawei_wmi_call(struct acpi_buffer *in, struct acpi_buffer *out)
+{
+       acpi_status status;
+
+       mutex_lock(&huawei_wmi->wmi_lock);
+       status = wmi_evaluate_method(HWMI_METHOD_GUID, 0, 1, in, out);
+       mutex_unlock(&huawei_wmi->wmi_lock);
+       if (ACPI_FAILURE(status)) {
+               dev_err(&huawei_wmi->pdev->dev, "Failed to evaluate wmi 
method\n");
+               return -ENODEV;
+       }
+
+       return 0;
+}
+
+/* HWMI takes a 64 bit input and returns either a package with 2 buffers, one 
of
+ * 4 bytes and the other of 256 bytes, or one buffer of size 0x104 (260) bytes.
+ * The first 4 bytes are ignored, we ignore the first 4 bytes buffer if we got 
a
+ * package, or skip the first 4 if a buffer of 0x104 is used. The first byte of
+ * the remaining 0x100 sized buffer has the return status of every call. In 
case
+ * the return status is non-zero, we return -ENODEV but still copy the returned
+ * buffer to the given buffer parameter (buf).
+ */
+static int huawei_wmi_cmd(u64 arg, u8 *buf, size_t buflen)
+{
+       struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
+       struct acpi_buffer in;
+       union acpi_object *obj;
+       size_t len;
+       int err, i;
+
+       in.length = sizeof(arg);
+       in.pointer = &arg;
+
+       /* Some models require calling HWMI twice to execute a command. We 
evaluate
+        * HWMI and if we get a non-zero return status we evaluate it again.
+        */
+       for (i = 0; i < 2; i++) {
+               err = huawei_wmi_call(&in, &out);
+               if (err)
+                       goto fail_cmd;
+
+               obj = out.pointer;
+               if (!obj) {
+                       err = -EIO;
+                       goto fail_cmd;
+               }
+
+               switch (obj->type) {
+               /* Models that implement both "legacy" and HWMI tend to return 
a 0x104
+                * sized buffer instead of a package of 0x4 and 0x100 buffers.
+                */
+               case ACPI_TYPE_BUFFER:
+                       if (obj->buffer.length == 0x104) {
+                               // Skip the first 4 bytes.
+                               obj->buffer.pointer += 4;
+                               len = 0x100;
+                       } else {
+                               dev_err(&huawei_wmi->pdev->dev, "Bad buffer 
length, got %d\n", obj->buffer.length);
+                               err = -EIO;
+                               goto fail_cmd;
+                       }
+
+                       break;
+               /* HWMI returns a package with 2 buffer elements, one of 4 
bytes and the
+                * other is 256 bytes.
+                */
+               case ACPI_TYPE_PACKAGE:
+                       if (obj->package.count != 2) {
+                               dev_err(&huawei_wmi->pdev->dev, "Bad package 
count, got %d\n", obj->package.count);
+                               err = -EIO;
+                               goto fail_cmd;
+                       }
+
+                       obj = &obj->package.elements[1];
+                       if (obj->type != ACPI_TYPE_BUFFER) {
+                               dev_err(&huawei_wmi->pdev->dev, "Bad package 
element type, got %d\n", obj->type);
+                               err = -EIO;
+                               goto fail_cmd;
+                       }
+                       len = obj->buffer.length;
+
+                       break;
+               /* Shouldn't get here! */
+               default:
+                       dev_err(&huawei_wmi->pdev->dev, "Unexpected obj type, 
got: %d\n", obj->type);
+                       err = -EIO;
+                       goto fail_cmd;
+               }
+
+               if (!*obj->buffer.pointer)
+                       break;
+       }
+
+       err = (*obj->buffer.pointer) ? -ENODEV : 0;
+
+       if (buf) {
+               len = min(buflen, len);
+               memcpy(buf, obj->buffer.pointer, len);
+       }
+
+fail_cmd:
+       kfree(out.pointer);
+       return err;
+}
+
+/* LEDs */
+
 static int huawei_wmi_micmute_led_set(struct led_classdev *led_cdev,
                enum led_brightness brightness)
 {
-       struct huawei_wmi *huawei = dev_get_drvdata(led_cdev->dev->parent);
-       acpi_status status;
-       union acpi_object args[3];
-       struct acpi_object_list arg_list = {
-               .pointer = args,
-               .count = ARRAY_SIZE(args),
-       };
-
-       args[0].type = args[1].type = args[2].type = ACPI_TYPE_INTEGER;
-       args[1].integer.value = 0x04;
-
-       if (strcmp(huawei->acpi_method, "SPIN") == 0) {
-               args[0].integer.value = 0;
-               args[2].integer.value = brightness ? 1 : 0;
-       } else if (strcmp(huawei->acpi_method, "WPIN") == 0) {
-               args[0].integer.value = 1;
-               args[2].integer.value = brightness ? 0 : 1;
+       /* This is a workaround until the "legacy" interface is implemented. */
+       if (quirks && quirks->ec_micmute) {
+               char *acpi_method;
+               acpi_handle handle;
+               acpi_status status;
+               union acpi_object args[3];
+               struct acpi_object_list arg_list = {
+                       .pointer = args,
+                       .count = ARRAY_SIZE(args),
+               };
+
+               handle = ec_get_handle();
+               if (!handle)
+                       return -ENODEV;
+
+               args[0].type = args[1].type = args[2].type = ACPI_TYPE_INTEGER;
+               args[1].integer.value = 0x04;
+
+               if (acpi_has_method(handle, "SPIN")) {
+                       acpi_method = "SPIN";
+                       args[0].integer.value = 0;
+                       args[2].integer.value = brightness ? 1 : 0;
+               } else if (acpi_has_method(handle, "WPIN")) {
+                       acpi_method = "WPIN";
+                       args[0].integer.value = 1;
+                       args[2].integer.value = brightness ? 0 : 1;
+               } else {
+                       return -ENODEV;
+               }
+
+               status = acpi_evaluate_object(handle, acpi_method, &arg_list, 
NULL);
+               if (ACPI_FAILURE(status))
+                       return -ENODEV;
+
+               return 0;
        } else {
-               return -EINVAL;
-       }
+               union hwmi_arg arg;
 
-       status = acpi_evaluate_object(huawei->handle, huawei->acpi_method, 
&arg_list, NULL);
-       if (ACPI_FAILURE(status))
-               return -ENXIO;
+               arg.cmd = MICMUTE_LED_SET;
+               arg.args[2] = brightness;
 
-       return 0;
+               return huawei_wmi_cmd(arg.cmd, NULL, 0);
+       }
 }
 
 static void huawei_wmi_leds_setup(struct device *dev)
 {
        struct huawei_wmi *huawei = dev_get_drvdata(dev);
 
-       huawei->handle = ec_get_handle();
-       if (!huawei->handle)
-               return;
-
-       if (acpi_has_method(huawei->handle, "SPIN"))
-               huawei->acpi_method = "SPIN";
-       else if (acpi_has_method(huawei->handle, "WPIN"))
-               huawei->acpi_method = "WPIN";
-       else
-               return;
-
        huawei->cdev.name = "platform::micmute";
        huawei->cdev.max_brightness = 1;
        huawei->cdev.brightness_set_blocking = &huawei_wmi_micmute_led_set;
@@ -258,6 +391,7 @@ static void huawei_wmi_input_exit(struct device *dev, const 
char *guid)
 
 static const struct wmi_device_id huawei_wmi_events_id_table[] = {
        { .guid_string = WMI0_EVENT_GUID },
+       { .guid_string = HWMI_EVENT_GUID },
        {  }
 };
 
@@ -284,7 +418,12 @@ static int huawei_wmi_probe(struct platform_device *pdev)
                guid++;
        }
 
-       huawei_wmi_leds_setup(&pdev->dev);
+       if (wmi_has_guid(HWMI_METHOD_GUID)) {
+               mutex_init(&huawei_wmi->wmi_lock);
+
+               huawei_wmi_leds_setup(&pdev->dev);
+       }
+
        return 0;
 }
 
@@ -299,6 +438,9 @@ static int huawei_wmi_remove(struct platform_device *pdev)
                guid++;
        }
 
+       if (wmi_has_guid(HWMI_METHOD_GUID)) {
+       }
+
        return 0;
 }
 
@@ -354,6 +496,7 @@ static __exit void huawei_wmi_exit(void)
 module_init(huawei_wmi_init);
 module_exit(huawei_wmi_exit);
 
+MODULE_ALIAS("wmi:"HWMI_METHOD_GUID);
 MODULE_DEVICE_TABLE(wmi, huawei_wmi_events_id_table);
 MODULE_AUTHOR("Ayman Bagabas <ayman.baga...@gmail.com>");
 MODULE_DESCRIPTION("Huawei WMI laptop extras driver");
-- 
2.21.0

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