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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * power/home/volume button support for
4 * Microsoft Surface Pro 3/4 tablet.
5 *
6 * Copyright (c) 2015 Intel Corporation.
7 * All rights reserved.
8 */
9
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/string.h>
14#include <linux/types.h>
15#include <linux/input.h>
16#include <linux/acpi.h>
17#include <linux/platform_device.h>
18#include <acpi/button.h>
19
20#define SURFACE_PRO3_BUTTON_HID "MSHW0028"
21#define SURFACE_PRO4_BUTTON_HID "MSHW0040"
22#define SURFACE_BUTTON_OBJ_NAME "VGBI"
23
24#define MSHW0040_DSM_REVISION 0x01
25#define MSHW0040_DSM_GET_OMPR 0x02 // get OEM Platform Revision
26static const guid_t MSHW0040_DSM_UUID =
27 GUID_INIT(0x6fd05c69, 0xcde3, 0x49f4, 0x95, 0xed, 0xab, 0x16, 0x65,
28 0x49, 0x80, 0x35);
29
30#define SURFACE_BUTTON_NOTIFY_TABLET_MODE 0xc8
31
32#define SURFACE_BUTTON_NOTIFY_PRESS_POWER 0xc6
33#define SURFACE_BUTTON_NOTIFY_RELEASE_POWER 0xc7
34
35#define SURFACE_BUTTON_NOTIFY_PRESS_HOME 0xc4
36#define SURFACE_BUTTON_NOTIFY_RELEASE_HOME 0xc5
37
38#define SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_UP 0xc0
39#define SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_UP 0xc1
40
41#define SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_DOWN 0xc2
42#define SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_DOWN 0xc3
43
44MODULE_AUTHOR("Chen Yu");
45MODULE_DESCRIPTION("Surface Pro3 Button Driver");
46MODULE_LICENSE("GPL v2");
47
48/*
49 * Power button, Home button, Volume buttons support is supposed to
50 * be covered by drivers/input/misc/soc_button_array.c, which is implemented
51 * according to "Windows ACPI Design Guide for SoC Platforms".
52 * However surface pro3 seems not to obey the specs, instead it uses
53 * device VGBI(MSHW0028) for dispatching the events.
54 * We choose acpi_driver rather than platform_driver/i2c_driver because
55 * although VGBI has an i2c resource connected to i2c controller, it
56 * is not embedded in any i2c controller's scope, thus neither platform_device
57 * will be created, nor i2c_client will be enumerated, we have to use
58 * acpi_driver.
59 */
60static const struct acpi_device_id surface_button_device_ids[] = {
61 {SURFACE_PRO3_BUTTON_HID, 0},
62 {SURFACE_PRO4_BUTTON_HID, 0},
63 {"", 0},
64};
65MODULE_DEVICE_TABLE(acpi, surface_button_device_ids);
66
67struct surface_button {
68 unsigned int type;
69 struct input_dev *input;
70 char phys[32]; /* for input device */
71 unsigned long pushed;
72 bool suspended;
73};
74
75static void surface_button_notify(acpi_handle handle, u32 event, void *data)
76{
77 struct device *dev = data;
78 struct surface_button *button = dev_get_drvdata(dev);
79 struct input_dev *input;
80 int key_code = KEY_RESERVED;
81 bool pressed = false;
82
83 switch (event) {
84 /* Power button press,release handle */
85 case SURFACE_BUTTON_NOTIFY_PRESS_POWER:
86 pressed = true;
87 fallthrough;
88 case SURFACE_BUTTON_NOTIFY_RELEASE_POWER:
89 key_code = KEY_POWER;
90 break;
91 /* Home button press,release handle */
92 case SURFACE_BUTTON_NOTIFY_PRESS_HOME:
93 pressed = true;
94 fallthrough;
95 case SURFACE_BUTTON_NOTIFY_RELEASE_HOME:
96 key_code = KEY_LEFTMETA;
97 break;
98 /* Volume up button press,release handle */
99 case SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_UP:
100 pressed = true;
101 fallthrough;
102 case SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_UP:
103 key_code = KEY_VOLUMEUP;
104 break;
105 /* Volume down button press,release handle */
106 case SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_DOWN:
107 pressed = true;
108 fallthrough;
109 case SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_DOWN:
110 key_code = KEY_VOLUMEDOWN;
111 break;
112 case SURFACE_BUTTON_NOTIFY_TABLET_MODE:
113 dev_warn_once(dev, "Tablet mode is not supported\n");
114 break;
115 default:
116 dev_info_ratelimited(dev, "Unsupported event [0x%x]\n", event);
117 break;
118 }
119 input = button->input;
120 if (key_code == KEY_RESERVED)
121 return;
122 if (pressed)
123 pm_wakeup_dev_event(dev, 0, button->suspended);
124 if (button->suspended)
125 return;
126 input_report_key(input, key_code, pressed?1:0);
127 input_sync(input);
128}
129
130#ifdef CONFIG_PM_SLEEP
131static int surface_button_suspend(struct device *dev)
132{
133 struct surface_button *button = dev_get_drvdata(dev);
134
135 button->suspended = true;
136 return 0;
137}
138
139static int surface_button_resume(struct device *dev)
140{
141 struct surface_button *button = dev_get_drvdata(dev);
142
143 button->suspended = false;
144 return 0;
145}
146#endif
147
148/*
149 * Surface Pro 4 and Surface Book 2 / Surface Pro 2017 use the same device
150 * ID (MSHW0040) for the power/volume buttons. Make sure this is the right
151 * device by checking for the _DSM method and OEM Platform Revision.
152 *
153 * Returns true if the driver should bind to this device, i.e. the device is
154 * either MSWH0028 (Pro 3) or MSHW0040 on a Pro 4 or Book 1.
155 */
156static bool surface_button_check_MSHW0040(struct device *dev, acpi_handle handle)
157{
158 union acpi_object *result;
159 u64 oem_platform_rev = 0; // valid revisions are nonzero
160
161 // get OEM platform revision
162 result = acpi_evaluate_dsm_typed(handle, &MSHW0040_DSM_UUID,
163 MSHW0040_DSM_REVISION,
164 MSHW0040_DSM_GET_OMPR,
165 NULL, ACPI_TYPE_INTEGER);
166
167 /*
168 * If evaluating the _DSM fails, the method is not present. This means
169 * that we have either MSHW0028 or MSHW0040 on Pro 4 or Book 1, so we
170 * should use this driver. We use revision 0 indicating it is
171 * unavailable.
172 */
173
174 if (result) {
175 oem_platform_rev = result->integer.value;
176 ACPI_FREE(result);
177 }
178
179 dev_dbg(dev, "OEM Platform Revision %llu\n", oem_platform_rev);
180
181 return oem_platform_rev == 0;
182}
183
184
185static int surface_button_probe(struct platform_device *pdev)
186{
187 struct surface_button *button;
188 struct acpi_device *device;
189 struct input_dev *input;
190 int error;
191
192 device = ACPI_COMPANION(&pdev->dev);
193 if (!device)
194 return -ENODEV;
195
196 if (strncmp(acpi_device_bid(device), SURFACE_BUTTON_OBJ_NAME,
197 strlen(SURFACE_BUTTON_OBJ_NAME)))
198 return -ENODEV;
199
200 if (!surface_button_check_MSHW0040(&pdev->dev, device->handle))
201 return -ENODEV;
202
203 button = kzalloc_obj(struct surface_button);
204 if (!button)
205 return -ENOMEM;
206
207 platform_set_drvdata(pdev, button);
208 button->input = input = input_allocate_device();
209 if (!input) {
210 error = -ENOMEM;
211 goto err_free_button;
212 }
213
214 snprintf(button->phys, sizeof(button->phys), "%s/buttons",
215 acpi_device_hid(device));
216
217 input->name = "Surface Pro 3/4 Buttons";
218 input->phys = button->phys;
219 input->id.bustype = BUS_HOST;
220 input->dev.parent = &pdev->dev;
221 input_set_capability(input, EV_KEY, KEY_POWER);
222 input_set_capability(input, EV_KEY, KEY_LEFTMETA);
223 input_set_capability(input, EV_KEY, KEY_VOLUMEUP);
224 input_set_capability(input, EV_KEY, KEY_VOLUMEDOWN);
225
226 error = input_register_device(input);
227 if (error)
228 goto err_free_input;
229
230 device_init_wakeup(&pdev->dev, true);
231
232 error = acpi_dev_install_notify_handler(device, ACPI_DEVICE_NOTIFY,
233 surface_button_notify, &pdev->dev);
234 if (error) {
235 device_init_wakeup(&pdev->dev, false);
236 input_unregister_device(input);
237 goto err_free_button;
238 }
239
240 dev_info(&pdev->dev, "%s [%s]\n", input->name, acpi_device_bid(device));
241
242 return 0;
243
244 err_free_input:
245 input_free_device(input);
246 err_free_button:
247 kfree(button);
248 return error;
249}
250
251static void surface_button_remove(struct platform_device *pdev)
252{
253 struct surface_button *button = platform_get_drvdata(pdev);
254
255 acpi_dev_remove_notify_handler(ACPI_COMPANION(&pdev->dev),
256 ACPI_DEVICE_NOTIFY, surface_button_notify);
257 device_init_wakeup(&pdev->dev, false);
258 input_unregister_device(button->input);
259 kfree(button);
260}
261
262static SIMPLE_DEV_PM_OPS(surface_button_pm,
263 surface_button_suspend, surface_button_resume);
264
265static struct platform_driver surface_button_driver = {
266 .probe = surface_button_probe,
267 .remove = surface_button_remove,
268 .driver = {
269 .name = "surface_pro3_button",
270 .acpi_match_table = surface_button_device_ids,
271 .pm = &surface_button_pm,
272 },
273};
274
275module_platform_driver(surface_button_driver);