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Subject[PATCH v2 2/2] HID: google: add support tablet mode switch for Whiskers
Date
Whiskers is a foldable base, and thus requires combining "base presence"
signal coming from EC with base state signal (folded/unfolded) coming
from USB/HID interface to produce proper SW_TABLET_MODE event.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Dmitry Torokhov <dtor@chromium.org>
---

v2 changes (addressing Benjamin comments):

- moved everything into hid-google-hammer.c
- dropped USB interface parsing in favor of report parsing
- removed product/model from tablet mode switch device (this is different
from what Benjamin requested - using Google USB vendor ID - but
it is purely host interface - BUS_HOST - not USB or I2C, and those do
not carry vendor/product ID typically. Userspace is simply supposed
to check capabilities of the device).

drivers/hid/hid-google-hammer.c | 413 ++++++++++++++++++++++++++++++--
1 file changed, 394 insertions(+), 19 deletions(-)

diff --git a/drivers/hid/hid-google-hammer.c b/drivers/hid/hid-google-hammer.c
index 6bf4da7ad63a..de3e7d055ca4 100644
--- a/drivers/hid/hid-google-hammer.c
+++ b/drivers/hid/hid-google-hammer.c
@@ -13,16 +13,268 @@
* any later version.
*/

+#include <linux/acpi.h>
#include <linux/hid.h>
#include <linux/leds.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeup.h>
+#include <asm/unaligned.h>

#include "hid-ids.h"

-#define MAX_BRIGHTNESS 100
+/*
+ * C(hrome)B(ase)A(ttached)S(witch) - switch exported by Chrome EC and reporting
+ * state of the "Whiskers" base - attached or detached. Whiskers USB device also
+ * reports position of the keyboard - folded or not. Combining base state and
+ * position allows us to generate proper "Tablet mode" events.
+ */
+struct cbas_ec {
+ struct device *dev; /* The platform device (EC) */
+ struct input_dev *input;
+ bool base_present;
+ struct notifier_block notifier;
+};

-/* HID usage for keyboard backlight (Alphanumeric display brightness) */
-#define HID_AD_BRIGHTNESS 0x00140046
+static struct cbas_ec cbas_ec;
+static DEFINE_SPINLOCK(cbas_ec_lock);
+static DEFINE_MUTEX(cbas_ec_reglock);
+
+static bool cbas_parse_base_state(const void *data)
+{
+ u32 switches = get_unaligned_le32(data);
+
+ return !!(switches & BIT(EC_MKBP_BASE_ATTACHED));
+}
+
+static int cbas_ec_query_base(struct cros_ec_device *ec_dev, bool get_state,
+ bool *state)
+{
+ struct ec_params_mkbp_info *params;
+ struct cros_ec_command *msg;
+ int ret;
+
+ msg = kzalloc(sizeof(*msg) + max(sizeof(u32), sizeof(*params)),
+ GFP_KERNEL);
+ if (!msg)
+ return -ENOMEM;
+
+ msg->command = EC_CMD_MKBP_INFO;
+ msg->version = 1;
+ msg->outsize = sizeof(*params);
+ msg->insize = sizeof(u32);
+ params = (struct ec_params_mkbp_info *)msg->data;
+ params->info_type = get_state ?
+ EC_MKBP_INFO_CURRENT : EC_MKBP_INFO_SUPPORTED;
+ params->event_type = EC_MKBP_EVENT_SWITCH;
+
+ ret = cros_ec_cmd_xfer_status(ec_dev, msg);
+ if (ret >= 0) {
+ if (ret != sizeof(u32)) {
+ dev_warn(ec_dev->dev, "wrong result size: %d != %zu\n",
+ ret, sizeof(u32));
+ ret = -EPROTO;
+ } else {
+ *state = cbas_parse_base_state(msg->data);
+ ret = 0;
+ }
+ }
+
+ kfree(msg);
+
+ return ret;
+}
+
+static int cbas_ec_notify(struct notifier_block *nb,
+ unsigned long queued_during_suspend,
+ void *_notify)
+{
+ struct cros_ec_device *ec = _notify;
+ unsigned long flags;
+ bool base_present;
+
+ if (ec->event_data.event_type == EC_MKBP_EVENT_SWITCH) {
+ base_present = cbas_parse_base_state(
+ &ec->event_data.data.switches);
+ dev_dbg(cbas_ec.dev,
+ "%s: base: %d\n", __func__, base_present);
+
+ if (device_may_wakeup(cbas_ec.dev) ||
+ !queued_during_suspend) {
+
+ pm_wakeup_event(cbas_ec.dev, 0);
+
+ spin_lock_irqsave(&cbas_ec_lock, flags);
+
+ /*
+ * While input layer dedupes the events, we do not want
+ * to disrupt the state reported by the base by
+ * overriding it with state reported by the LID. Only
+ * report changes, as we assume that on attach the base
+ * is not folded.
+ */
+ if (base_present != cbas_ec.base_present) {
+ input_report_switch(cbas_ec.input,
+ SW_TABLET_MODE,
+ !base_present);
+ input_sync(cbas_ec.input);
+ cbas_ec.base_present = base_present;
+ }
+
+ spin_unlock_irqrestore(&cbas_ec_lock, flags);
+ }
+ }
+
+ return NOTIFY_OK;
+}
+
+static __maybe_unused int cbas_ec_resume(struct device *dev)
+{
+ struct cros_ec_device *ec = dev_get_drvdata(dev->parent);
+ bool base_present;
+ int error;
+
+ error = cbas_ec_query_base(ec, true, &base_present);
+ if (error) {
+ dev_warn(dev, "failed to fetch base state on resume: %d\n",
+ error);
+ } else {
+ spin_lock_irq(&cbas_ec_lock);
+
+ cbas_ec.base_present = base_present;
+
+ /*
+ * Only report if base is disconnected. If base is connected,
+ * it will resend its state on resume, and we'll update it
+ * in hammer_event().
+ */
+ if (!cbas_ec.base_present) {
+ input_report_switch(cbas_ec.input, SW_TABLET_MODE, 1);
+ input_sync(cbas_ec.input);
+ }
+
+ spin_unlock_irq(&cbas_ec_lock);
+ }
+
+ return 0;
+}
+
+static const SIMPLE_DEV_PM_OPS(cbas_ec_pm_ops, NULL, cbas_ec_resume);
+
+static void cbas_ec_set_input(struct input_dev *input)
+{
+ /* Take the lock so hammer_event() does not race with us here */
+ spin_lock_irq(&cbas_ec_lock);
+ cbas_ec.input = input;
+ spin_unlock_irq(&cbas_ec_lock);
+}
+
+static int __cbas_ec_probe(struct platform_device *pdev)
+{
+ struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+ struct input_dev *input;
+ bool base_supported;
+ int error;
+
+ error = cbas_ec_query_base(ec, false, &base_supported);
+ if (error)
+ return error;
+
+ if (!base_supported)
+ return -ENXIO;
+
+ input = devm_input_allocate_device(&pdev->dev);
+ if (!input)
+ return -ENOMEM;
+
+ input->name = "Whiskers Tablet Mode Switch";
+ input->id.bustype = BUS_HOST;
+
+ input_set_capability(input, EV_SW, SW_TABLET_MODE);
+
+ error = input_register_device(input);
+ if (error) {
+ dev_err(&pdev->dev, "cannot register input device: %d\n",
+ error);
+ return error;
+ }
+
+ /* Seed the state */
+ error = cbas_ec_query_base(ec, true, &cbas_ec.base_present);
+ if (error) {
+ dev_err(&pdev->dev, "cannot query base state: %d\n", error);
+ return error;
+ }
+
+ input_report_switch(input, SW_TABLET_MODE, !cbas_ec.base_present);
+
+ cbas_ec_set_input(input);
+
+ cbas_ec.dev = &pdev->dev;
+ cbas_ec.notifier.notifier_call = cbas_ec_notify;
+ error = blocking_notifier_chain_register(&ec->event_notifier,
+ &cbas_ec.notifier);
+ if (error) {
+ dev_err(&pdev->dev, "cannot register notifier: %d\n", error);
+ cbas_ec_set_input(NULL);
+ return error;
+ }
+
+ device_init_wakeup(&pdev->dev, true);
+ return 0;
+}
+
+static int cbas_ec_probe(struct platform_device *pdev)
+{
+ int retval;
+
+ mutex_lock(&cbas_ec_reglock);
+
+ if (cbas_ec.input) {
+ retval = -EBUSY;
+ goto out;
+ }
+
+ retval = __cbas_ec_probe(pdev);
+
+out:
+ mutex_unlock(&cbas_ec_reglock);
+ return retval;
+}
+
+static int cbas_ec_remove(struct platform_device *pdev)
+{
+ struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+
+ mutex_lock(&cbas_ec_reglock);
+
+ blocking_notifier_chain_unregister(&ec->event_notifier,
+ &cbas_ec.notifier);
+ cbas_ec_set_input(NULL);
+
+ mutex_unlock(&cbas_ec_reglock);
+ return 0;
+}
+
+static const struct acpi_device_id cbas_ec_acpi_ids[] = {
+ { "GOOG000B", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(acpi, cbas_ec_acpi_ids);
+
+static struct platform_driver cbas_ec_driver = {
+ .probe = cbas_ec_probe,
+ .remove = cbas_ec_remove,
+ .driver = {
+ .name = "cbas_ec",
+ .acpi_match_table = ACPI_PTR(cbas_ec_acpi_ids),
+ .pm = &cbas_ec_pm_ops,
+ },
+};
+
+#define MAX_BRIGHTNESS 100

struct hammer_kbd_leds {
struct led_classdev cdev;
@@ -90,33 +342,130 @@ static int hammer_register_leds(struct hid_device *hdev)
return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
}

-static int hammer_input_configured(struct hid_device *hdev,
- struct hid_input *hi)
+#define HID_UP_GOOGLEVENDOR 0xffd10000
+#define HID_VD_KBD_FOLDED 0x00000019
+#define WHISKERS_KBD_FOLDED (HID_UP_GOOGLEVENDOR | HID_VD_KBD_FOLDED)
+
+/* HID usage for keyboard backlight (Alphanumeric display brightness) */
+#define HID_AD_BRIGHTNESS 0x00140046
+
+static int hammer_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+ struct hid_field *field,
+ struct hid_usage *usage,
+ unsigned long **bit, int *max)
{
- struct list_head *report_list =
- &hdev->report_enum[HID_OUTPUT_REPORT].report_list;
+ if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+ usage->hid == WHISKERS_KBD_FOLDED) {
+ /*
+ * We do not want to have this usage mapped as it will get
+ * mixed in with "base attached" signal and delivered over
+ * separate input device for tablet switch mode.
+ */
+ return -1;
+ }
+
+ return 0;
+}
+
+static int hammer_event(struct hid_device *hid, struct hid_field *field,
+ struct hid_usage *usage, __s32 value)
+{
+ unsigned long flags;
+
+ if (hid->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+ usage->hid == WHISKERS_KBD_FOLDED) {
+ spin_lock_irqsave(&cbas_ec_lock, flags);
+
+ hid_dbg(hid, "%s: base: %d, folded: %d\n", __func__,
+ cbas_ec.base_present, value);
+
+ /*
+ * We should not get event if base is detached, but in case
+ * we happen to service HID and EC notifications out of order
+ * let's still check the "base present" flag.
+ */
+ if (cbas_ec.input && cbas_ec.base_present) {
+ input_report_switch(cbas_ec.input,
+ SW_TABLET_MODE, value);
+ input_sync(cbas_ec.input);
+ }
+
+ spin_unlock_irqrestore(&cbas_ec_lock, flags);
+ return 1; /* We handled this event */
+ }
+
+ return 0;
+}
+
+static bool hammer_is_keyboard_interface(struct hid_device *hdev)
+{
+ struct hid_report_enum *re = &hdev->report_enum[HID_INPUT_REPORT];
struct hid_report *report;

- if (list_empty(report_list))
- return 0;
+ list_for_each_entry(report, &re->report_list, list)
+ if (report->application == HID_GD_KEYBOARD)
+ return true;

- report = list_first_entry(report_list, struct hid_report, list);
+ return false;
+}
+
+static bool hammer_has_backlight_control(struct hid_device *hdev)
+{
+ struct hid_report_enum *re = &hdev->report_enum[HID_OUTPUT_REPORT];
+ struct hid_report *report;
+ int i, j;

- if (report->maxfield == 1 &&
- report->field[0]->application == HID_GD_KEYBOARD &&
- report->field[0]->maxusage == 1 &&
- report->field[0]->usage[0].hid == HID_AD_BRIGHTNESS) {
- int err = hammer_register_leds(hdev);
+ list_for_each_entry(report, &re->report_list, list) {
+ if (report->application != HID_GD_KEYBOARD)
+ continue;

- if (err)
+ for (i = 0; i < report->maxfield; i++) {
+ struct hid_field *field = report->field[i];
+
+ for (j = 0; j < field->maxusage; j++)
+ if (field->usage[j].hid == HID_AD_BRIGHTNESS)
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static int hammer_probe(struct hid_device *hdev,
+ const struct hid_device_id *id)
+{
+ int error;
+
+ /*
+ * We always want to poll for, and handle tablet mode events from
+ * Whiskers, even when nobody has opened the input device. This also
+ * prevents the hid core from dropping early tablet mode events from
+ * the device.
+ */
+ if (hdev->product == USB_DEVICE_ID_GOOGLE_WHISKERS &&
+ hammer_is_keyboard_interface(hdev))
+ hdev->quirks |= HID_QUIRK_ALWAYS_POLL;
+
+ error = hid_parse(hdev);
+ if (error)
+ return error;
+
+ error = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+ if (error)
+ return error;
+
+ if (hammer_has_backlight_control(hdev)) {
+ error = hammer_register_leds(hdev);
+ if (error)
hid_warn(hdev,
"Failed to register keyboard backlight: %d\n",
- err);
+ error);
}

return 0;
}

+
static const struct hid_device_id hammer_devices[] = {
{ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER) },
@@ -133,8 +482,34 @@ MODULE_DEVICE_TABLE(hid, hammer_devices);
static struct hid_driver hammer_driver = {
.name = "hammer",
.id_table = hammer_devices,
- .input_configured = hammer_input_configured,
+ .probe = hammer_probe,
+ .input_mapping = hammer_input_mapping,
+ .event = hammer_event,
};
-module_hid_driver(hammer_driver);
+
+static int __init hammer_init(void)
+{
+ int error;
+
+ error = platform_driver_register(&cbas_ec_driver);
+ if (error)
+ return error;
+
+ error = hid_register_driver(&hammer_driver);
+ if (error) {
+ platform_driver_unregister(&cbas_ec_driver);
+ return error;
+ }
+
+ return 0;
+}
+module_init(hammer_init);
+
+static void __exit hammer_exit(void)
+{
+ hid_unregister_driver(&hammer_driver);
+ platform_driver_unregister(&cbas_ec_driver);
+}
+module_exit(hammer_exit);

MODULE_LICENSE("GPL");
--
2.19.0.605.g01d371f741-goog
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