// SPDX-License-Identifier: GPL-2.0+ /* * Surface System Aggregator Module (SSAM) HID transport driver for the legacy * keyboard interface (KBD/TC=0x08 subsystem). Provides support for the * integrated HID keyboard on Surface Laptops 1 and 2. * * Copyright (C) 2019-2021 Maximilian Luz */ #include #include #include #include #include #include #include #include "surface_hid_core.h" /* -- SAM interface (KBD). -------------------------------------------------- */ #define KBD_FEATURE_REPORT_SIZE 7 /* 6 + report ID */ enum surface_kbd_cid { SURFACE_KBD_CID_GET_DESCRIPTOR = 0x00, SURFACE_KBD_CID_SET_CAPSLOCK_LED = 0x01, SURFACE_KBD_CID_EVT_INPUT_GENERIC = 0x03, SURFACE_KBD_CID_EVT_INPUT_HOTKEYS = 0x04, SURFACE_KBD_CID_GET_FEATURE_REPORT = 0x0b, }; static int ssam_kbd_get_descriptor(struct surface_hid_device *shid, u8 entry, u8 *buf, size_t len) { struct ssam_request rqst; struct ssam_response rsp; int status; rqst.target_category = shid->uid.category; rqst.target_id = shid->uid.target; rqst.command_id = SURFACE_KBD_CID_GET_DESCRIPTOR; rqst.instance_id = shid->uid.instance; rqst.flags = SSAM_REQUEST_HAS_RESPONSE; rqst.length = sizeof(entry); rqst.payload = &entry; rsp.capacity = len; rsp.length = 0; rsp.pointer = buf; status = ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(entry)); if (status) return status; if (rsp.length != len) { dev_err(shid->dev, "invalid descriptor length: got %zu, expected, %zu\n", rsp.length, len); return -EPROTO; } return 0; } static int ssam_kbd_set_caps_led(struct surface_hid_device *shid, bool value) { struct ssam_request rqst; u8 value_u8 = value; rqst.target_category = shid->uid.category; rqst.target_id = shid->uid.target; rqst.command_id = SURFACE_KBD_CID_SET_CAPSLOCK_LED; rqst.instance_id = shid->uid.instance; rqst.flags = 0; rqst.length = sizeof(value_u8); rqst.payload = &value_u8; return ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, NULL, sizeof(value_u8)); } static int ssam_kbd_get_feature_report(struct surface_hid_device *shid, u8 *buf, size_t len) { struct ssam_request rqst; struct ssam_response rsp; u8 payload = 0; int status; rqst.target_category = shid->uid.category; rqst.target_id = shid->uid.target; rqst.command_id = SURFACE_KBD_CID_GET_FEATURE_REPORT; rqst.instance_id = shid->uid.instance; rqst.flags = SSAM_REQUEST_HAS_RESPONSE; rqst.length = sizeof(payload); rqst.payload = &payload; rsp.capacity = len; rsp.length = 0; rsp.pointer = buf; status = ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(payload)); if (status) return status; if (rsp.length != len) { dev_err(shid->dev, "invalid feature report length: got %zu, expected, %zu\n", rsp.length, len); return -EPROTO; } return 0; } static bool ssam_kbd_is_input_event(const struct ssam_event *event) { if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_GENERIC) return true; if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_HOTKEYS) return true; return false; } static u32 ssam_kbd_event_fn(struct ssam_event_notifier *nf, const struct ssam_event *event) { struct surface_hid_device *shid = container_of(nf, struct surface_hid_device, notif); /* * Check against device UID manually, as registry and device target * category doesn't line up. */ if (shid->uid.category != event->target_category) return 0; if (shid->uid.target != event->target_id) return 0; if (shid->uid.instance != event->instance_id) return 0; if (!ssam_kbd_is_input_event(event)) return 0; hid_input_report(shid->hid, HID_INPUT_REPORT, (u8 *)&event->data[0], event->length, 0); return SSAM_NOTIF_HANDLED; } /* -- Transport driver (KBD). ----------------------------------------------- */ static int skbd_get_caps_led_value(struct hid_device *hid, u8 rprt_id, u8 *buf, size_t len) { struct hid_field *field; unsigned int offset, size; int i; /* Get LED field. */ field = hidinput_get_led_field(hid); if (!field) return -ENOENT; /* Check if we got the correct report. */ if (len != hid_report_len(field->report)) return -ENOENT; if (rprt_id != field->report->id) return -ENOENT; /* Get caps lock LED index. */ for (i = 0; i < field->report_count; i++) if ((field->usage[i].hid & 0xffff) == 0x02) break; if (i == field->report_count) return -ENOENT; /* Extract value. */ size = field->report_size; offset = field->report_offset + i * size; return !!hid_field_extract(hid, buf + 1, size, offset); } static int skbd_output_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len) { int caps_led; int status; caps_led = skbd_get_caps_led_value(shid->hid, rprt_id, buf, len); if (caps_led < 0) return -EIO; /* Only caps LED output reports are supported. */ status = ssam_kbd_set_caps_led(shid, caps_led); if (status < 0) return status; return len; } static int skbd_get_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len) { u8 report[KBD_FEATURE_REPORT_SIZE]; int status; /* * The keyboard only has a single hard-coded read-only feature report * of size KBD_FEATURE_REPORT_SIZE. Try to load it and compare its * report ID against the requested one. */ if (len < ARRAY_SIZE(report)) return -ENOSPC; status = ssam_kbd_get_feature_report(shid, report, ARRAY_SIZE(report)); if (status < 0) return status; if (rprt_id != report[0]) return -ENOENT; memcpy(buf, report, ARRAY_SIZE(report)); return len; } static int skbd_set_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len) { /* Not supported. See skbd_get_feature_report() for details. */ return -EIO; } /* -- Driver setup. --------------------------------------------------------- */ static int surface_kbd_probe(struct platform_device *pdev) { struct ssam_controller *ctrl; struct surface_hid_device *shid; /* Add device link to EC. */ ctrl = ssam_client_bind(&pdev->dev); if (IS_ERR(ctrl)) return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl); shid = devm_kzalloc(&pdev->dev, sizeof(*shid), GFP_KERNEL); if (!shid) return -ENOMEM; shid->dev = &pdev->dev; shid->ctrl = ctrl; shid->uid.domain = SSAM_DOMAIN_SERIALHUB; shid->uid.category = SSAM_SSH_TC_KBD; shid->uid.target = SSAM_SSH_TID_KIP; shid->uid.instance = 0; shid->uid.function = 0; shid->notif.base.priority = 1; shid->notif.base.fn = ssam_kbd_event_fn; shid->notif.event.reg = SSAM_EVENT_REGISTRY_SAM; shid->notif.event.id.target_category = shid->uid.category; shid->notif.event.id.instance = shid->uid.instance; shid->notif.event.mask = SSAM_EVENT_MASK_NONE; shid->notif.event.flags = 0; shid->ops.get_descriptor = ssam_kbd_get_descriptor; shid->ops.output_report = skbd_output_report; shid->ops.get_feature_report = skbd_get_feature_report; shid->ops.set_feature_report = skbd_set_feature_report; platform_set_drvdata(pdev, shid); return surface_hid_device_add(shid); } static void surface_kbd_remove(struct platform_device *pdev) { surface_hid_device_destroy(platform_get_drvdata(pdev)); } static const struct acpi_device_id surface_kbd_match[] = { { "MSHW0096" }, { }, }; MODULE_DEVICE_TABLE(acpi, surface_kbd_match); static struct platform_driver surface_kbd_driver = { .probe = surface_kbd_probe, .remove = surface_kbd_remove, .driver = { .name = "surface_keyboard", .acpi_match_table = surface_kbd_match, .pm = &surface_hid_pm_ops, .probe_type = PROBE_PREFER_ASYNCHRONOUS, }, }; module_platform_driver(surface_kbd_driver); MODULE_AUTHOR("Maximilian Luz "); MODULE_DESCRIPTION("HID legacy transport driver for Surface System Aggregator Module"); MODULE_LICENSE("GPL");