From: Kerem Karabay <kek...@gmail.com>

The Touch Bars found on x86 Macs support two USB configurations: one
where the device presents itself as a HID keyboard and can display
predefined sets of keys, and one where the operating system has full
control over what is displayed. This commit adds a driver for the
display functionality of the first configuration.

Note that currently only T2 Macs are supported.

This driver is based on previous work done by Ronald Tschalär
<ron...@innovation.ch>.

Signed-off-by: Kerem Karabay <kek...@gmail.com>
Co-developed-by: Aditya Garg <gargadity...@live.com>
Signed-off-by: Aditya Garg <gargadity...@live.com>
---
 .../ABI/testing/sysfs-driver-hid-appletb-kbd  |  13 +
 drivers/hid/Kconfig                           |  11 +
 drivers/hid/Makefile                          |   1 +
 drivers/hid/hid-appletb-kbd.c                 | 304 ++++++++++++++++++
 drivers/hid/hid-quirks.c                      |   4 +-
 5 files changed, 332 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-hid-appletb-kbd
 create mode 100644 drivers/hid/hid-appletb-kbd.c

diff --git a/Documentation/ABI/testing/sysfs-driver-hid-appletb-kbd 
b/Documentation/ABI/testing/sysfs-driver-hid-appletb-kbd
new file mode 100644
index 000000000..2a19584d0
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-hid-appletb-kbd
@@ -0,0 +1,13 @@
+What:          /sys/bus/hid/drivers/hid-appletb-kbd/<dev>/mode
+Date:          September, 2023
+KernelVersion: 6.5
+Contact:       linux-in...@vger.kernel.org
+Description:
+               The set of keys displayed on the Touch Bar.
+               Valid values are:
+               == =================
+               0  Escape key only
+               1  Function keys
+               2  Media/brightness keys
+               3  None
+               == =================
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 4988c1fb2..72b665eda 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -158,6 +158,17 @@ config HID_APPLETB_BL
          To compile this driver as a module, choose M here: the
          module will be called hid-appletb-bl.
 
+config HID_APPLETB_KBD
+       tristate "Apple Touch Bar Keyboard Mode"
+       depends on USB_HID
+       help
+         Say Y here if you want support for the keyboard mode (escape,
+         function, media and brightness keys) of Touch Bars on x86 MacBook
+         Pros.
+
+         To compile this driver as a module, choose M here: the
+         module will be called hid-appletb-kbd.
+
 config HID_ASUS
        tristate "Asus"
        depends on USB_HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 1d825a474..d903c9a26 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_HID_ACRUX)               += hid-axff.o
 obj-$(CONFIG_HID_APPLE)                += hid-apple.o
 obj-$(CONFIG_HID_APPLEIR)      += hid-appleir.o
 obj-$(CONFIG_HID_APPLETB_BL)   += hid-appletb-bl.o
+obj-$(CONFIG_HID_APPLETB_KBD)  += hid-appletb-kbd.o
 obj-$(CONFIG_HID_CREATIVE_SB0540)      += hid-creative-sb0540.o
 obj-$(CONFIG_HID_ASUS)         += hid-asus.o
 obj-$(CONFIG_HID_AUREAL)       += hid-aureal.o
diff --git a/drivers/hid/hid-appletb-kbd.c b/drivers/hid/hid-appletb-kbd.c
new file mode 100644
index 000000000..ecac68fc7
--- /dev/null
+++ b/drivers/hid/hid-appletb-kbd.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple Touch Bar Keyboard Mode Driver
+ *
+ * Copyright (c) 2017-2018 Ronald Tschalär
+ * Copyright (c) 2022-2023 Kerem Karabay <kek...@gmail.com>
+ * Copyright (c) 2024 Aditya Garg <gargadity...@live.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/hid.h>
+#include <linux/usb.h>
+#include <linux/input.h>
+#include <linux/sysfs.h>
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/input/sparse-keymap.h>
+
+#include "hid-ids.h"
+
+#define APPLETB_KBD_MODE_ESC   0
+#define APPLETB_KBD_MODE_FN    1
+#define APPLETB_KBD_MODE_SPCL  2
+#define APPLETB_KBD_MODE_OFF   3
+#define APPLETB_KBD_MODE_MAX   APPLETB_KBD_MODE_OFF
+
+#define HID_USAGE_MODE         0x00ff0004
+
+static int appletb_tb_def_mode = APPLETB_KBD_MODE_SPCL;
+module_param_named(mode, appletb_tb_def_mode, int, 0444);
+MODULE_PARM_DESC(mode, "Default touchbar mode:\n"
+                        "    0 - escape key only\n"
+                        "    1 - function-keys\n"
+                        "    [2] - special keys");
+
+struct appletb_kbd {
+       struct hid_field *mode_field;
+
+       u8 saved_mode;
+       u8 current_mode;
+};
+
+static const struct key_entry appletb_kbd_keymap[] = {
+       { KE_KEY, KEY_ESC, { KEY_ESC } },
+       { KE_KEY, KEY_F1,  { KEY_BRIGHTNESSDOWN } },
+       { KE_KEY, KEY_F2,  { KEY_BRIGHTNESSUP } },
+       { KE_KEY, KEY_F3,  { KEY_RESERVED } },
+       { KE_KEY, KEY_F4,  { KEY_RESERVED } },
+       { KE_KEY, KEY_F5,  { KEY_KBDILLUMDOWN } },
+       { KE_KEY, KEY_F6,  { KEY_KBDILLUMUP } },
+       { KE_KEY, KEY_F7,  { KEY_PREVIOUSSONG } },
+       { KE_KEY, KEY_F8,  { KEY_PLAYPAUSE } },
+       { KE_KEY, KEY_F9,  { KEY_NEXTSONG } },
+       { KE_KEY, KEY_F10, { KEY_MUTE } },
+       { KE_KEY, KEY_F11, { KEY_VOLUMEDOWN } },
+       { KE_KEY, KEY_F12, { KEY_VOLUMEUP } },
+       { KE_END, 0 }
+};
+
+static int appletb_kbd_set_mode(struct appletb_kbd *kbd, u8 mode)
+{
+       struct hid_report *report = kbd->mode_field->report;
+       struct hid_device *hdev = report->device;
+       int ret;
+
+       ret = hid_hw_power(hdev, PM_HINT_FULLON);
+       if (ret) {
+               hid_err(hdev, "Device didn't resume (%pe)\n", ERR_PTR(ret));
+               return ret;
+       }
+
+       ret = hid_set_field(kbd->mode_field, 0, mode);
+       if (ret) {
+               hid_err(hdev, "Failed to set mode field to %u (%pe)\n", mode, 
ERR_PTR(ret));
+               goto power_normal;
+       }
+
+       hid_hw_request(hdev, report, HID_REQ_SET_REPORT);
+
+       kbd->current_mode = mode;
+
+power_normal:
+       hid_hw_power(hdev, PM_HINT_NORMAL);
+
+       return ret;
+}
+
+static ssize_t mode_show(struct device *dev,
+                        struct device_attribute *attr, char *buf)
+{
+       struct appletb_kbd *kbd = dev_get_drvdata(dev);
+
+       return sysfs_emit(buf, "%d\n", kbd->current_mode);
+}
+
+static ssize_t mode_store(struct device *dev,
+                         struct device_attribute *attr,
+                         const char *buf, size_t size)
+{
+       struct appletb_kbd *kbd = dev_get_drvdata(dev);
+       u8 mode;
+       int ret;
+
+       ret = kstrtou8(buf, 0, &mode);
+       if (ret)
+               return ret;
+
+       if (mode > APPLETB_KBD_MODE_MAX)
+               return -EINVAL;
+
+       ret = appletb_kbd_set_mode(kbd, mode);
+
+       return ret < 0 ? ret : size;
+}
+static DEVICE_ATTR_RW(mode);
+
+struct attribute *appletb_kbd_attrs[] = {
+       &dev_attr_mode.attr,
+       NULL
+};
+ATTRIBUTE_GROUPS(appletb_kbd);
+
+static int appletb_tb_key_to_slot(unsigned int code)
+{
+       switch (code) {
+       case KEY_ESC:
+               return 0;
+       case KEY_F1 ... KEY_F10:
+               return code - KEY_F1 + 1;
+       case KEY_F11 ... KEY_F12:
+               return code - KEY_F11 + 11;
+
+       default:
+               return -EINVAL;
+       }
+}
+
+static int appletb_kbd_hid_event(struct hid_device *hdev, struct hid_field 
*field,
+                                     struct hid_usage *usage, __s32 value)
+{
+       struct appletb_kbd *kbd = hid_get_drvdata(hdev);
+       struct key_entry *translation;
+       struct input_dev *input;
+       int slot;
+
+       if ((usage->hid & HID_USAGE_PAGE) != HID_UP_KEYBOARD || usage->type != 
EV_KEY)
+               return 0;
+
+       input = field->hidinput->input;
+
+       /*
+        * Skip non-touch-bar keys.
+        *
+        * Either the touch bar itself or usbhid generate a slew of key-down
+        * events for all the meta keys. None of which we're at all interested
+        * in.
+        */
+       slot = appletb_tb_key_to_slot(usage->code);
+       if (slot < 0)
+               return 0;
+
+       translation = sparse_keymap_entry_from_scancode(input, usage->code);
+
+       if (translation && kbd->current_mode == APPLETB_KBD_MODE_SPCL) {
+               input_event(input, usage->type, translation->keycode, value);
+
+               return 1;
+       }
+
+       return kbd->current_mode == APPLETB_KBD_MODE_OFF;
+}
+
+static int appletb_kbd_input_configured(struct hid_device *hdev, struct 
hid_input *hidinput)
+{
+       int idx;
+       struct input_dev *input = hidinput->input;
+
+       /*
+        * Clear various input capabilities that are blindly set by the hid
+        * driver (usbkbd.c)
+        */
+       memset(input->evbit, 0, sizeof(input->evbit));
+       memset(input->keybit, 0, sizeof(input->keybit));
+       memset(input->ledbit, 0, sizeof(input->ledbit));
+
+       __set_bit(EV_REP, input->evbit);
+
+       sparse_keymap_setup(input, appletb_kbd_keymap, NULL);
+
+       for (idx = 0; appletb_kbd_keymap[idx].type != KE_END; idx++) {
+               input_set_capability(input, EV_KEY, 
appletb_kbd_keymap[idx].code);
+       }
+
+       return 0;
+}
+
+static int appletb_kbd_probe(struct hid_device *hdev, const struct 
hid_device_id *id)
+{
+       struct appletb_kbd *kbd;
+       struct device *dev = &hdev->dev;
+       struct hid_field *mode_field;
+       int ret;
+
+       ret = hid_parse(hdev);
+       if (ret)
+               return dev_err_probe(dev, ret, "HID parse failed\n");
+
+       mode_field = hid_find_field(hdev, HID_OUTPUT_REPORT,
+                                   HID_GD_KEYBOARD, HID_USAGE_MODE);
+       if (!mode_field)
+               return -ENODEV;
+
+       kbd = devm_kzalloc(dev, sizeof(*kbd), GFP_KERNEL);
+       if (!kbd)
+               return -ENOMEM;
+
+       kbd->mode_field = mode_field;
+
+       ret = hid_hw_start(hdev, HID_CONNECT_HIDINPUT);
+       if (ret)
+               return dev_err_probe(dev, ret, "HID hw start failed\n");
+
+       ret = hid_hw_open(hdev);
+       if (ret) {
+               dev_err_probe(dev, ret, "HID hw open failed\n");
+               goto stop_hw;
+       }
+
+       ret = appletb_kbd_set_mode(kbd, appletb_tb_def_mode);
+       if (ret) {
+               dev_err_probe(dev, ret, "Failed to set touchbar mode\n");
+               goto close_hw;
+       }
+
+       hid_set_drvdata(hdev, kbd);
+
+       return 0;
+
+close_hw:
+       hid_hw_close(hdev);
+stop_hw:
+       hid_hw_stop(hdev);
+       return ret;
+}
+
+static void appletb_kbd_remove(struct hid_device *hdev)
+{
+       struct appletb_kbd *kbd = hid_get_drvdata(hdev);
+
+       appletb_kbd_set_mode(kbd, APPLETB_KBD_MODE_OFF);
+
+       hid_hw_close(hdev);
+       hid_hw_stop(hdev);
+}
+
+#ifdef CONFIG_PM
+static int appletb_kbd_suspend(struct hid_device *hdev, pm_message_t msg)
+{
+       struct appletb_kbd *kbd = hid_get_drvdata(hdev);
+
+       kbd->saved_mode = kbd->current_mode;
+       appletb_kbd_set_mode(kbd, APPLETB_KBD_MODE_OFF);
+
+       return 0;
+}
+
+static int appletb_kbd_reset_resume(struct hid_device *hdev)
+{
+       struct appletb_kbd *kbd = hid_get_drvdata(hdev);
+
+       appletb_kbd_set_mode(kbd, kbd->saved_mode);
+
+       return 0;
+}
+#endif
+
+static const struct hid_device_id appletb_kbd_hid_ids[] = {
+       /* MacBook Pro's 2018, 2019, with T2 chip: iBridge Display */
+       { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_TOUCHBAR_DISPLAY) },
+       { }
+};
+MODULE_DEVICE_TABLE(hid, appletb_kbd_hid_ids);
+
+static struct hid_driver appletb_kbd_hid_driver = {
+       .name = "hid-appletb-kbd",
+       .id_table = appletb_kbd_hid_ids,
+       .probe = appletb_kbd_probe,
+       .remove = appletb_kbd_remove,
+       .event = appletb_kbd_hid_event,
+       .input_configured = appletb_kbd_input_configured,
+#ifdef CONFIG_PM
+       .suspend = appletb_kbd_suspend,
+       .reset_resume = appletb_kbd_reset_resume,
+#endif
+       .driver.dev_groups = appletb_kbd_groups,
+};
+module_hid_driver(appletb_kbd_hid_driver);
+
+MODULE_AUTHOR("Ronald Tschalär");
+MODULE_AUTHOR("Kerem Karabay <kek...@gmail.com>");
+MODULE_DESCRIPTION("MacBookPro Touch Bar Keyboard Mode Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
index 818d41a35..7c576d654 100644
--- a/drivers/hid/hid-quirks.c
+++ b/drivers/hid/hid-quirks.c
@@ -328,7 +328,6 @@ static const struct hid_device_id hid_have_special_driver[] 
= {
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_GEYSER1_TP_ONLY) },
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_MAGIC_KEYBOARD_2021) },
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_MAGIC_KEYBOARD_FINGERPRINT_2021) },
-       { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_TOUCHBAR_DISPLAY) },
 #endif
 #if IS_ENABLED(CONFIG_HID_APPLEIR)
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_IRCONTROL) },
@@ -340,6 +339,9 @@ static const struct hid_device_id hid_have_special_driver[] 
= {
 #if IS_ENABLED(CONFIG_HID_APPLETB_BL)
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_TOUCHBAR_BACKLIGHT) },
 #endif
+#if IS_ENABLED(CONFIG_HID_APPLETB_KBD)
+       { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, 
USB_DEVICE_ID_APPLE_TOUCHBAR_DISPLAY) },
+#endif
 #if IS_ENABLED(CONFIG_HID_ASUS)
        { HID_I2C_DEVICE(USB_VENDOR_ID_ASUSTEK, 
USB_DEVICE_ID_ASUSTEK_I2C_KEYBOARD) },
        { HID_I2C_DEVICE(USB_VENDOR_ID_ASUSTEK, 
USB_DEVICE_ID_ASUSTEK_I2C_TOUCHPAD) },
-- 
2.43.0

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