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1// SPDX-License-Identifier: GPL-2.0+2/*3 * Surface System Aggregator Module (SSAM) HID transport driver for the legacy4 * keyboard interface (KBD/TC=0x08 subsystem). Provides support for the5 * integrated HID keyboard on Surface Laptops 1 and 2.6 *7 * Copyright (C) 2019-2021 Maximilian Luz <luzmaximilian@gmail.com>8 */9 10#include <linux/unaligned.h>11#include <linux/hid.h>12#include <linux/kernel.h>13#include <linux/module.h>14#include <linux/platform_device.h>15#include <linux/types.h>16 17#include <linux/surface_aggregator/controller.h>18 19#include "surface_hid_core.h"20 21 22/* -- SAM interface (KBD). -------------------------------------------------- */23 24#define KBD_FEATURE_REPORT_SIZE 7 /* 6 + report ID */25 26enum surface_kbd_cid {27 SURFACE_KBD_CID_GET_DESCRIPTOR = 0x00,28 SURFACE_KBD_CID_SET_CAPSLOCK_LED = 0x01,29 SURFACE_KBD_CID_EVT_INPUT_GENERIC = 0x03,30 SURFACE_KBD_CID_EVT_INPUT_HOTKEYS = 0x04,31 SURFACE_KBD_CID_GET_FEATURE_REPORT = 0x0b,32};33 34static int ssam_kbd_get_descriptor(struct surface_hid_device *shid, u8 entry, u8 *buf, size_t len)35{36 struct ssam_request rqst;37 struct ssam_response rsp;38 int status;39 40 rqst.target_category = shid->uid.category;41 rqst.target_id = shid->uid.target;42 rqst.command_id = SURFACE_KBD_CID_GET_DESCRIPTOR;43 rqst.instance_id = shid->uid.instance;44 rqst.flags = SSAM_REQUEST_HAS_RESPONSE;45 rqst.length = sizeof(entry);46 rqst.payload = &entry;47 48 rsp.capacity = len;49 rsp.length = 0;50 rsp.pointer = buf;51 52 status = ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(entry));53 if (status)54 return status;55 56 if (rsp.length != len) {57 dev_err(shid->dev, "invalid descriptor length: got %zu, expected, %zu\n",58 rsp.length, len);59 return -EPROTO;60 }61 62 return 0;63}64 65static int ssam_kbd_set_caps_led(struct surface_hid_device *shid, bool value)66{67 struct ssam_request rqst;68 u8 value_u8 = value;69 70 rqst.target_category = shid->uid.category;71 rqst.target_id = shid->uid.target;72 rqst.command_id = SURFACE_KBD_CID_SET_CAPSLOCK_LED;73 rqst.instance_id = shid->uid.instance;74 rqst.flags = 0;75 rqst.length = sizeof(value_u8);76 rqst.payload = &value_u8;77 78 return ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, NULL, sizeof(value_u8));79}80 81static int ssam_kbd_get_feature_report(struct surface_hid_device *shid, u8 *buf, size_t len)82{83 struct ssam_request rqst;84 struct ssam_response rsp;85 u8 payload = 0;86 int status;87 88 rqst.target_category = shid->uid.category;89 rqst.target_id = shid->uid.target;90 rqst.command_id = SURFACE_KBD_CID_GET_FEATURE_REPORT;91 rqst.instance_id = shid->uid.instance;92 rqst.flags = SSAM_REQUEST_HAS_RESPONSE;93 rqst.length = sizeof(payload);94 rqst.payload = &payload;95 96 rsp.capacity = len;97 rsp.length = 0;98 rsp.pointer = buf;99 100 status = ssam_retry(ssam_request_do_sync_onstack, shid->ctrl, &rqst, &rsp, sizeof(payload));101 if (status)102 return status;103 104 if (rsp.length != len) {105 dev_err(shid->dev, "invalid feature report length: got %zu, expected, %zu\n",106 rsp.length, len);107 return -EPROTO;108 }109 110 return 0;111}112 113static bool ssam_kbd_is_input_event(const struct ssam_event *event)114{115 if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_GENERIC)116 return true;117 118 if (event->command_id == SURFACE_KBD_CID_EVT_INPUT_HOTKEYS)119 return true;120 121 return false;122}123 124static u32 ssam_kbd_event_fn(struct ssam_event_notifier *nf, const struct ssam_event *event)125{126 struct surface_hid_device *shid = container_of(nf, struct surface_hid_device, notif);127 128 /*129 * Check against device UID manually, as registry and device target130 * category doesn't line up.131 */132 133 if (shid->uid.category != event->target_category)134 return 0;135 136 if (shid->uid.target != event->target_id)137 return 0;138 139 if (shid->uid.instance != event->instance_id)140 return 0;141 142 if (!ssam_kbd_is_input_event(event))143 return 0;144 145 hid_input_report(shid->hid, HID_INPUT_REPORT, (u8 *)&event->data[0], event->length, 0);146 return SSAM_NOTIF_HANDLED;147}148 149 150/* -- Transport driver (KBD). ----------------------------------------------- */151 152static int skbd_get_caps_led_value(struct hid_device *hid, u8 rprt_id, u8 *buf, size_t len)153{154 struct hid_field *field;155 unsigned int offset, size;156 int i;157 158 /* Get LED field. */159 field = hidinput_get_led_field(hid);160 if (!field)161 return -ENOENT;162 163 /* Check if we got the correct report. */164 if (len != hid_report_len(field->report))165 return -ENOENT;166 167 if (rprt_id != field->report->id)168 return -ENOENT;169 170 /* Get caps lock LED index. */171 for (i = 0; i < field->report_count; i++)172 if ((field->usage[i].hid & 0xffff) == 0x02)173 break;174 175 if (i == field->report_count)176 return -ENOENT;177 178 /* Extract value. */179 size = field->report_size;180 offset = field->report_offset + i * size;181 return !!hid_field_extract(hid, buf + 1, size, offset);182}183 184static int skbd_output_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)185{186 int caps_led;187 int status;188 189 caps_led = skbd_get_caps_led_value(shid->hid, rprt_id, buf, len);190 if (caps_led < 0)191 return -EIO; /* Only caps LED output reports are supported. */192 193 status = ssam_kbd_set_caps_led(shid, caps_led);194 if (status < 0)195 return status;196 197 return len;198}199 200static int skbd_get_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)201{202 u8 report[KBD_FEATURE_REPORT_SIZE];203 int status;204 205 /*206 * The keyboard only has a single hard-coded read-only feature report207 * of size KBD_FEATURE_REPORT_SIZE. Try to load it and compare its208 * report ID against the requested one.209 */210 211 if (len < ARRAY_SIZE(report))212 return -ENOSPC;213 214 status = ssam_kbd_get_feature_report(shid, report, ARRAY_SIZE(report));215 if (status < 0)216 return status;217 218 if (rprt_id != report[0])219 return -ENOENT;220 221 memcpy(buf, report, ARRAY_SIZE(report));222 return len;223}224 225static int skbd_set_feature_report(struct surface_hid_device *shid, u8 rprt_id, u8 *buf, size_t len)226{227 /* Not supported. See skbd_get_feature_report() for details. */228 return -EIO;229}230 231 232/* -- Driver setup. --------------------------------------------------------- */233 234static int surface_kbd_probe(struct platform_device *pdev)235{236 struct ssam_controller *ctrl;237 struct surface_hid_device *shid;238 239 /* Add device link to EC. */240 ctrl = ssam_client_bind(&pdev->dev);241 if (IS_ERR(ctrl))242 return PTR_ERR(ctrl) == -ENODEV ? -EPROBE_DEFER : PTR_ERR(ctrl);243 244 shid = devm_kzalloc(&pdev->dev, sizeof(*shid), GFP_KERNEL);245 if (!shid)246 return -ENOMEM;247 248 shid->dev = &pdev->dev;249 shid->ctrl = ctrl;250 251 shid->uid.domain = SSAM_DOMAIN_SERIALHUB;252 shid->uid.category = SSAM_SSH_TC_KBD;253 shid->uid.target = SSAM_SSH_TID_KIP;254 shid->uid.instance = 0;255 shid->uid.function = 0;256 257 shid->notif.base.priority = 1;258 shid->notif.base.fn = ssam_kbd_event_fn;259 shid->notif.event.reg = SSAM_EVENT_REGISTRY_SAM;260 shid->notif.event.id.target_category = shid->uid.category;261 shid->notif.event.id.instance = shid->uid.instance;262 shid->notif.event.mask = SSAM_EVENT_MASK_NONE;263 shid->notif.event.flags = 0;264 265 shid->ops.get_descriptor = ssam_kbd_get_descriptor;266 shid->ops.output_report = skbd_output_report;267 shid->ops.get_feature_report = skbd_get_feature_report;268 shid->ops.set_feature_report = skbd_set_feature_report;269 270 platform_set_drvdata(pdev, shid);271 return surface_hid_device_add(shid);272}273 274static void surface_kbd_remove(struct platform_device *pdev)275{276 surface_hid_device_destroy(platform_get_drvdata(pdev));277}278 279static const struct acpi_device_id surface_kbd_match[] = {280 { "MSHW0096" },281 { },282};283MODULE_DEVICE_TABLE(acpi, surface_kbd_match);284 285static struct platform_driver surface_kbd_driver = {286 .probe = surface_kbd_probe,287 .remove_new = surface_kbd_remove,288 .driver = {289 .name = "surface_keyboard",290 .acpi_match_table = surface_kbd_match,291 .pm = &surface_hid_pm_ops,292 .probe_type = PROBE_PREFER_ASYNCHRONOUS,293 },294};295module_platform_driver(surface_kbd_driver);296 297MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");298MODULE_DESCRIPTION("HID legacy transport driver for Surface System Aggregator Module");299MODULE_LICENSE("GPL");300