1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Surface System Aggregator Module (SSAM) HID transport driver for the legacy
4 * keyboard interface (KBD/TC=0x08 subsystem). Provides support for the
5 * 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
26 enum 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
ssam_kbd_get_descriptor(struct surface_hid_device * shid,u8 entry,u8 * buf,size_t len)34 static 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
ssam_kbd_set_caps_led(struct surface_hid_device * shid,bool value)65 static 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
ssam_kbd_get_feature_report(struct surface_hid_device * shid,u8 * buf,size_t len)81 static 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
ssam_kbd_is_input_event(const struct ssam_event * event)113 static 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
ssam_kbd_event_fn(struct ssam_event_notifier * nf,const struct ssam_event * event)124 static 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 target
130 * 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
skbd_get_caps_led_value(struct hid_device * hid,u8 rprt_id,u8 * buf,size_t len)152 static 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
skbd_output_report(struct surface_hid_device * shid,u8 rprt_id,u8 * buf,size_t len)184 static 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
skbd_get_feature_report(struct surface_hid_device * shid,u8 rprt_id,u8 * buf,size_t len)200 static 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 report
207 * of size KBD_FEATURE_REPORT_SIZE. Try to load it and compare its
208 * 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
skbd_set_feature_report(struct surface_hid_device * shid,u8 rprt_id,u8 * buf,size_t len)225 static 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
surface_kbd_probe(struct platform_device * pdev)234 static 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
surface_kbd_remove(struct platform_device * pdev)274 static void surface_kbd_remove(struct platform_device *pdev)
275 {
276 surface_hid_device_destroy(platform_get_drvdata(pdev));
277 }
278
279 static const struct acpi_device_id surface_kbd_match[] = {
280 { "MSHW0096" },
281 { },
282 };
283 MODULE_DEVICE_TABLE(acpi, surface_kbd_match);
284
285 static 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 };
295 module_platform_driver(surface_kbd_driver);
296
297 MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
298 MODULE_DESCRIPTION("HID legacy transport driver for Surface System Aggregator Module");
299 MODULE_LICENSE("GPL");
300