thinkpad_acpi: Add support for keyboard backlight

This patch adds support for controlling keyboard backlight via standard
linux led class interface (::kbd_backlight). It uses ACPI HKEY device with
MLCG and MLCS methods.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Tested-by: Fabio D'Urso <fabiodurso@hotmail.it>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

1 files changed, 206 insertions, 0 deletions

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 0bed4733c4f0..a268a7abf8ab 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -303,6 +303,7 @@ static struct {
         u32 hotkey_mask:1;
         u32 hotkey_wlsw:1;
         u32 hotkey_tablet:1;
+        u32 kbdlight:1;
         u32 light:1;
         u32 light_status:1;
         u32 bright_acpimode:1;
@@ -4986,6 +4987,207 @@ static struct ibm_struct video_driver_data = {
 #endif /* CONFIG_THINKPAD_ACPI_VIDEO */
 
 /*************************************************************************
+ * Keyboard backlight subdriver
+ */
+
+static int kbdlight_set_level(int level)
+{
+        if (!hkey_handle)
+                return -ENXIO;
+
+        if (!acpi_evalf(hkey_handle, NULL, "MLCS", "dd", level))
+                return -EIO;
+
+        return 0;
+}
+
+static int kbdlight_get_level(void)
+{
+        int status = 0;
+
+        if (!hkey_handle)
+                return -ENXIO;
+
+        if (!acpi_evalf(hkey_handle, &status, "MLCG", "dd", 0))
+                return -EIO;
+
+        if (status < 0)
+                return status;
+
+        return status & 0x3;
+}
+
+static bool kbdlight_is_supported(void)
+{
+        int status = 0;
+
+        if (!hkey_handle)
+                return false;
+
+        if (!acpi_has_method(hkey_handle, "MLCG")) {
+                vdbg_printk(TPACPI_DBG_INIT, "kbdlight MLCG is unavailable\n");
+                return false;
+        }
+
+        if (!acpi_evalf(hkey_handle, &status, "MLCG", "qdd", 0)) {
+                vdbg_printk(TPACPI_DBG_INIT, "kbdlight MLCG failed\n");
+                return false;
+        }
+
+        if (status < 0) {
+                vdbg_printk(TPACPI_DBG_INIT, "kbdlight MLCG err: %d\n", status);
+                return false;
+        }
+
+        vdbg_printk(TPACPI_DBG_INIT, "kbdlight MLCG returned 0x%x\n", status);
+        /*
+         * Guessed test for keyboard backlight:
+         *
+         * Machines with backlight keyboard return:
+         *   b010100000010000000XX - ThinkPad X1 Carbon 3rd
+         *   b110100010010000000XX - ThinkPad x230
+         *   b010100000010000000XX - ThinkPad x240
+         *   b010100000010000000XX - ThinkPad W541
+         * (XX is current backlight level)
+         *
+         * Machines without backlight keyboard return:
+         *   b10100001000000000000 - ThinkPad x230
+         *   b10110001000000000000 - ThinkPad E430
+         *   b00000000000000000000 - ThinkPad E450
+         *
+         * Candidate BITs for detection test (XOR):
+         *   b01000000001000000000
+         *              ^
+         */
+        return status & BIT(9);
+}
+
+static void kbdlight_set_worker(struct work_struct *work)
+{
+        struct tpacpi_led_classdev *data =
+                        container_of(work, struct tpacpi_led_classdev, work);
+
+        if (likely(tpacpi_lifecycle == TPACPI_LIFE_RUNNING))
+                kbdlight_set_level(data->new_state);
+}
+
+static void kbdlight_sysfs_set(struct led_classdev *led_cdev,
+                        enum led_brightness brightness)
+{
+        struct tpacpi_led_classdev *data =
+                        container_of(led_cdev,
+                                     struct tpacpi_led_classdev,
+                                     led_classdev);
+        data->new_state = brightness;
+        queue_work(tpacpi_wq, &data->work);
+}
+
+static enum led_brightness kbdlight_sysfs_get(struct led_classdev *led_cdev)
+{
+        int level;
+
+        level = kbdlight_get_level();
+        if (level < 0)
+                return 0;
+
+        return level;
+}
+
+static struct tpacpi_led_classdev tpacpi_led_kbdlight = {
+        .led_classdev = {
+                .name           = "tpacpi::kbd_backlight",
+                .max_brightness = 2,
+                .brightness_set = &kbdlight_sysfs_set,
+                .brightness_get = &kbdlight_sysfs_get,
+                .flags          = LED_CORE_SUSPENDRESUME,
+        }
+};
+
+static int __init kbdlight_init(struct ibm_init_struct *iibm)
+{
+        int rc;
+
+        vdbg_printk(TPACPI_DBG_INIT, "initializing kbdlight subdriver\n");
+
+        TPACPI_ACPIHANDLE_INIT(hkey);
+        INIT_WORK(&tpacpi_led_kbdlight.work, kbdlight_set_worker);
+
+        if (!kbdlight_is_supported()) {
+                tp_features.kbdlight = 0;
+                vdbg_printk(TPACPI_DBG_INIT, "kbdlight is unsupported\n");
+                return 1;
+        }
+
+        tp_features.kbdlight = 1;
+
+        rc = led_classdev_register(&tpacpi_pdev->dev,
+                                   &tpacpi_led_kbdlight.led_classdev);
+        if (rc < 0) {
+                tp_features.kbdlight = 0;
+                return rc;
+        }
+
+        return 0;
+}
+
+static void kbdlight_exit(void)
+{
+        if (tp_features.kbdlight)
+                led_classdev_unregister(&tpacpi_led_kbdlight.led_classdev);
+        flush_workqueue(tpacpi_wq);
+}
+
+static int kbdlight_read(struct seq_file *m)
+{
+        int level;
+
+        if (!tp_features.kbdlight) {
+                seq_printf(m, "status:\t\tnot supported\n");
+        } else {
+                level = kbdlight_get_level();
+                if (level < 0)
+                        seq_printf(m, "status:\t\terror %d\n", level);
+                else
+                        seq_printf(m, "status:\t\t%d\n", level);
+                seq_printf(m, "commands:\t0, 1, 2\n");
+        }
+
+        return 0;
+}
+
+static int kbdlight_write(char *buf)
+{
+        char *cmd;
+        int level = -1;
+
+        if (!tp_features.kbdlight)
+                return -ENODEV;
+
+        while ((cmd = next_cmd(&buf))) {
+                if (strlencmp(cmd, "0") == 0)
+                        level = 0;
+                else if (strlencmp(cmd, "1") == 0)
+                        level = 1;
+                else if (strlencmp(cmd, "2") == 0)
+                        level = 2;
+                else
+                        return -EINVAL;
+        }
+
+        if (level == -1)
+                return -EINVAL;
+
+        return kbdlight_set_level(level);
+}
+
+static struct ibm_struct kbdlight_driver_data = {
+        .name = "kbdlight",
+        .read = kbdlight_read,
+        .write = kbdlight_write,
+        .exit = kbdlight_exit,
+};
+
+/*************************************************************************
  * Light (thinklight) subdriver
  */
 
@@ -9207,6 +9409,10 @@ static struct ibm_init_struct ibms_init[] __initdata = {
         },
 #endif
         {
+                .init = kbdlight_init,
+                .data = &kbdlight_driver_data,
+        },
+        {
                 .init = light_init,
                 .data = &light_driver_data,
         },