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platform/x86: ideapad-laptop: Add support for keyboard backlights usi…
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…ng KBLC ACPI symbol

Newer Lenovo laptops seem to use the KBLC symbol to control the backlight
Add support for handling the keyboard backlight on these devices

Signed-off-by: Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
Link: https://lore.kernel.org/r/20230827161940.485200-1-stuart.a.hayhurst@gmail.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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Stuart Hayhurst authored and Hans de Goede committed Aug 28, 2023
1 parent 5ee473b commit ecaa186
Showing 1 changed file with 112 additions and 6 deletions.
118 changes: 112 additions & 6 deletions drivers/platform/x86/ideapad-laptop.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@

#include <linux/acpi.h>
#include <linux/backlight.h>
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/debugfs.h>
Expand Down Expand Up @@ -85,6 +86,31 @@ enum {
SALS_FNLOCK_OFF = 0xf,
};

/*
* These correspond to the number of supported states - 1
* Future keyboard types may need a new system, if there's a collision
* KBD_BL_TRISTATE_AUTO has no way to report or set the auto state
* so it effectively has 3 states, but needs to handle 4
*/
enum {
KBD_BL_STANDARD = 1,
KBD_BL_TRISTATE = 2,
KBD_BL_TRISTATE_AUTO = 3,
};

#define KBD_BL_QUERY_TYPE 0x1
#define KBD_BL_TRISTATE_TYPE 0x5
#define KBD_BL_TRISTATE_AUTO_TYPE 0x7

#define KBD_BL_COMMAND_GET 0x2
#define KBD_BL_COMMAND_SET 0x3
#define KBD_BL_COMMAND_TYPE GENMASK(7, 4)

#define KBD_BL_GET_BRIGHTNESS GENMASK(15, 1)
#define KBD_BL_SET_BRIGHTNESS GENMASK(19, 16)

#define KBD_BL_KBLC_CHANGED_EVENT 12

struct ideapad_dytc_priv {
enum platform_profile_option current_profile;
struct platform_profile_handler pprof;
Expand Down Expand Up @@ -122,6 +148,7 @@ struct ideapad_private {
} features;
struct {
bool initialized;
int type;
struct led_classdev led;
unsigned int last_brightness;
} kbd_bl;
Expand Down Expand Up @@ -242,6 +269,16 @@ static int exec_sals(acpi_handle handle, unsigned long arg)
return exec_simple_method(handle, "SALS", arg);
}

static int exec_kblc(acpi_handle handle, unsigned long arg)
{
return exec_simple_method(handle, "KBLC", arg);
}

static int eval_kblc(acpi_handle handle, unsigned long cmd, unsigned long *res)
{
return eval_int_with_arg(handle, "KBLC", cmd, res);
}

static int eval_dytc(acpi_handle handle, unsigned long cmd, unsigned long *res)
{
return eval_int_with_arg(handle, "DYTC", cmd, res);
Expand Down Expand Up @@ -1275,16 +1312,47 @@ static void ideapad_backlight_notify_brightness(struct ideapad_private *priv)
/*
* keyboard backlight
*/
static int ideapad_kbd_bl_check_tristate(int type)
{
return (type == KBD_BL_TRISTATE) || (type == KBD_BL_TRISTATE_AUTO);
}

static int ideapad_kbd_bl_brightness_get(struct ideapad_private *priv)
{
unsigned long hals;
unsigned long value;
int err;

err = eval_hals(priv->adev->handle, &hals);
if (ideapad_kbd_bl_check_tristate(priv->kbd_bl.type)) {
err = eval_kblc(priv->adev->handle,
FIELD_PREP(KBD_BL_COMMAND_TYPE, priv->kbd_bl.type) |
KBD_BL_COMMAND_GET,
&value);

if (err)
return err;

/* Convert returned value to brightness level */
value = FIELD_GET(KBD_BL_GET_BRIGHTNESS, value);

/* Off, low or high */
if (value <= priv->kbd_bl.led.max_brightness)
return value;

/* Auto, report as off */
if (value == priv->kbd_bl.led.max_brightness + 1)
return 0;

/* Unknown value */
dev_warn(&priv->platform_device->dev,
"Unknown keyboard backlight value: %lu", value);
return -EINVAL;
}

err = eval_hals(priv->adev->handle, &value);
if (err)
return err;

return !!test_bit(HALS_KBD_BL_STATE_BIT, &hals);
return !!test_bit(HALS_KBD_BL_STATE_BIT, &value);
}

static enum led_brightness ideapad_kbd_bl_led_cdev_brightness_get(struct led_classdev *led_cdev)
Expand All @@ -1296,7 +1364,21 @@ static enum led_brightness ideapad_kbd_bl_led_cdev_brightness_get(struct led_cla

static int ideapad_kbd_bl_brightness_set(struct ideapad_private *priv, unsigned int brightness)
{
int err = exec_sals(priv->adev->handle, brightness ? SALS_KBD_BL_ON : SALS_KBD_BL_OFF);
int err;
unsigned long value;
int type = priv->kbd_bl.type;

if (ideapad_kbd_bl_check_tristate(type)) {
if (brightness > priv->kbd_bl.led.max_brightness)
return -EINVAL;

value = FIELD_PREP(KBD_BL_SET_BRIGHTNESS, brightness) |
FIELD_PREP(KBD_BL_COMMAND_TYPE, type) |
KBD_BL_COMMAND_SET;
err = exec_kblc(priv->adev->handle, value);
} else {
err = exec_sals(priv->adev->handle, brightness ? SALS_KBD_BL_ON : SALS_KBD_BL_OFF);
}

if (err)
return err;
Expand Down Expand Up @@ -1349,8 +1431,13 @@ static int ideapad_kbd_bl_init(struct ideapad_private *priv)

priv->kbd_bl.last_brightness = brightness;

if (ideapad_kbd_bl_check_tristate(priv->kbd_bl.type)) {
priv->kbd_bl.led.max_brightness = 2;
} else {
priv->kbd_bl.led.max_brightness = 1;
}

priv->kbd_bl.led.name = "platform::" LED_FUNCTION_KBD_BACKLIGHT;
priv->kbd_bl.led.max_brightness = 1;
priv->kbd_bl.led.brightness_get = ideapad_kbd_bl_led_cdev_brightness_get;
priv->kbd_bl.led.brightness_set_blocking = ideapad_kbd_bl_led_cdev_brightness_set;
priv->kbd_bl.led.flags = LED_BRIGHT_HW_CHANGED;
Expand Down Expand Up @@ -1461,6 +1548,7 @@ static void ideapad_acpi_notify(acpi_handle handle, u32 event, void *data)
case 2:
ideapad_backlight_notify_power(priv);
break;
case KBD_BL_KBLC_CHANGED_EVENT:
case 1:
/*
* Some IdeaPads report event 1 every ~20
Expand Down Expand Up @@ -1562,13 +1650,31 @@ static void ideapad_check_features(struct ideapad_private *priv)
if (test_bit(HALS_FNLOCK_SUPPORT_BIT, &val))
priv->features.fn_lock = true;

if (test_bit(HALS_KBD_BL_SUPPORT_BIT, &val))
if (test_bit(HALS_KBD_BL_SUPPORT_BIT, &val)) {
priv->features.kbd_bl = true;
priv->kbd_bl.type = KBD_BL_STANDARD;
}

if (test_bit(HALS_USB_CHARGING_SUPPORT_BIT, &val))
priv->features.usb_charging = true;
}
}

if (acpi_has_method(handle, "KBLC")) {
if (!eval_kblc(priv->adev->handle, KBD_BL_QUERY_TYPE, &val)) {
if (val == KBD_BL_TRISTATE_TYPE) {
priv->features.kbd_bl = true;
priv->kbd_bl.type = KBD_BL_TRISTATE;
} else if (val == KBD_BL_TRISTATE_AUTO_TYPE) {
priv->features.kbd_bl = true;
priv->kbd_bl.type = KBD_BL_TRISTATE_AUTO;
} else {
dev_warn(&priv->platform_device->dev,
"Unknown keyboard type: %lu",
val);
}
}
}
}

#if IS_ENABLED(CONFIG_ACPI_WMI)
Expand Down

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