Newer thinkpad models have a mute hotkey with a led to indicate
current mute states. Thinkpad BIOS provides ACPI interfaces for
getting and changing the hardware mute along with the led.

Signed-off-by: Alex Hung <alex.h...@canonical.com>
---
 drivers/platform/x86/thinkpad_acpi.c | 89 ++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/drivers/platform/x86/thinkpad_acpi.c 
b/drivers/platform/x86/thinkpad_acpi.c
index adb3a4e..d39bf18 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -8364,6 +8364,91 @@ static struct ibm_struct fan_driver_data = {
        .resume = fan_resume,
 };
 
+/*************************************************************************
+ * Mute LED subdriver
+ */
+
+enum {
+       TPACPI_AML_MUTE_READ_MASK = 0x01,
+};
+
+static int mute_led_on_off(int state)
+{
+       int output;
+       acpi_handle temp;
+
+       if (!ACPI_SUCCESS(acpi_get_handle(hkey_handle, "SSMS", &temp))) {
+               pr_warn("Thinkpad ACPI has no GSMS interface.\n");
+               return -EIO;
+       }
+
+       if (!acpi_evalf(hkey_handle, &output, "SSMS", "dd", state))
+               return -EIO;
+
+       return 0;
+}
+
+static void mute_led_set(struct led_classdev *led_cdev,
+       enum led_brightness value)
+{
+       if (value > 0)
+               mute_led_on_off(1);
+       else
+               mute_led_on_off(0);
+}
+
+static enum led_brightness mute_led_get(struct led_classdev *led_cdev)
+{
+       int state = 0;
+       acpi_handle temp;
+
+       if (!ACPI_SUCCESS(acpi_get_handle(hkey_handle, "GSMS", &temp))) {
+               pr_warn("Thinkpad ACPI has no GSMS interface.\n");
+               return -EIO;
+       }
+
+       if (!acpi_evalf(hkey_handle, &state, "GSMS", "dd"))
+               pr_warn("failed to get hardware mute state.\n");
+
+       state &= TPACPI_AML_MUTE_READ_MASK;
+
+       return state;
+}
+
+static struct tpacpi_led_classdev tpacpi_led_mute = {
+       .led_classdev = {
+               .name = "tpacpi::mute",
+               .brightness_set = mute_led_set,
+               .brightness_get = mute_led_get,
+       }
+};
+
+static int mute_led_init(struct ibm_init_struct *iibm)
+{
+       acpi_handle temp;
+
+       if (!ACPI_SUCCESS(acpi_get_handle(hkey_handle, "GSMS", &temp)))
+               return 0;
+
+       return led_classdev_register(&tpacpi_pdev->dev,
+               &tpacpi_led_mute.led_classdev);
+}
+
+static void mute_led_exit(void)
+{
+       acpi_handle temp;
+
+       if (!ACPI_SUCCESS(acpi_get_handle(hkey_handle, "GSMS", &temp)))
+               return;
+
+       led_classdev_unregister(&tpacpi_led_mute.led_classdev);
+}
+
+static struct ibm_struct mute_led_driver_data = {
+       .name = "mute_led",
+       .exit = mute_led_exit,
+};
+
 /****************************************************************************
  ****************************************************************************
  *
@@ -8782,6 +8867,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
                .init = fan_init,
                .data = &fan_driver_data,
        },
+       {
+               .init = mute_led_init,
+               .data = &mute_led_driver_data,
+       },
 };
 
 static int __init set_ibm_param(const char *val, struct kernel_param *kp)
-- 
1.8.1.2

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