1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2017 Red Hat, Inc
4 */
5
6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/libps2.h>
11#include <linux/i2c.h>
12#include <linux/serio.h>
13#include <linux/slab.h>
14#include <linux/workqueue.h>
15#include "psmouse.h"
16
17struct psmouse_smbus_dev {
18 struct i2c_board_info board;
19 struct psmouse *psmouse;
20 struct i2c_client *client;
21 struct list_head node;
22 bool dead;
23 bool need_deactivate;
24};
25
26static LIST_HEAD(psmouse_smbus_list);
27static DEFINE_MUTEX(psmouse_smbus_mutex);
28
29static struct workqueue_struct *psmouse_smbus_wq;
30
31static void psmouse_smbus_check_adapter(struct i2c_adapter *adapter)
32{
33 struct psmouse_smbus_dev *smbdev;
34
35 if (!i2c_check_functionality(adap: adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
36 return;
37
38 mutex_lock(&psmouse_smbus_mutex);
39
40 list_for_each_entry(smbdev, &psmouse_smbus_list, node) {
41 if (smbdev->dead)
42 continue;
43
44 if (smbdev->client)
45 continue;
46
47 /*
48 * Here would be a good place to check if device is actually
49 * present, but it seems that SMBus will not respond unless we
50 * fully reset PS/2 connection. So cross our fingers, and try
51 * to switch over, hopefully our system will not have too many
52 * "host notify" I2C adapters.
53 */
54 psmouse_dbg(smbdev->psmouse,
55 "SMBus candidate adapter appeared, triggering rescan\n");
56 serio_rescan(serio: smbdev->psmouse->ps2dev.serio);
57 }
58
59 mutex_unlock(lock: &psmouse_smbus_mutex);
60}
61
62static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
63{
64 struct psmouse_smbus_dev *smbdev, *tmp;
65
66 mutex_lock(&psmouse_smbus_mutex);
67
68 list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
69 if (smbdev->client != client)
70 continue;
71
72 kfree(objp: client->dev.platform_data);
73 client->dev.platform_data = NULL;
74
75 if (!smbdev->dead) {
76 psmouse_dbg(smbdev->psmouse,
77 "Marking SMBus companion %s as gone\n",
78 dev_name(&smbdev->client->dev));
79 smbdev->dead = true;
80 device_link_remove(consumer: &smbdev->client->dev,
81 supplier: &smbdev->psmouse->ps2dev.serio->dev);
82 serio_rescan(serio: smbdev->psmouse->ps2dev.serio);
83 } else {
84 list_del(entry: &smbdev->node);
85 kfree(objp: smbdev);
86 }
87 }
88
89 mutex_unlock(lock: &psmouse_smbus_mutex);
90}
91
92static int psmouse_smbus_notifier_call(struct notifier_block *nb,
93 unsigned long action, void *data)
94{
95 struct device *dev = data;
96
97 switch (action) {
98 case BUS_NOTIFY_ADD_DEVICE:
99 if (dev->type == &i2c_adapter_type)
100 psmouse_smbus_check_adapter(to_i2c_adapter(dev));
101 break;
102
103 case BUS_NOTIFY_REMOVED_DEVICE:
104 if (dev->type == &i2c_client_type)
105 psmouse_smbus_detach_i2c_client(to_i2c_client(dev));
106 break;
107 }
108
109 return 0;
110}
111
112static struct notifier_block psmouse_smbus_notifier = {
113 .notifier_call = psmouse_smbus_notifier_call,
114};
115
116static psmouse_ret_t psmouse_smbus_process_byte(struct psmouse *psmouse)
117{
118 return PSMOUSE_FULL_PACKET;
119}
120
121static int psmouse_smbus_reconnect(struct psmouse *psmouse)
122{
123 struct psmouse_smbus_dev *smbdev = psmouse->private;
124
125 if (smbdev->need_deactivate)
126 psmouse_deactivate(psmouse);
127
128 return 0;
129}
130
131struct psmouse_smbus_removal_work {
132 struct work_struct work;
133 struct i2c_client *client;
134};
135
136static void psmouse_smbus_remove_i2c_device(struct work_struct *work)
137{
138 struct psmouse_smbus_removal_work *rwork =
139 container_of(work, struct psmouse_smbus_removal_work, work);
140
141 dev_dbg(&rwork->client->dev, "destroying SMBus companion device\n");
142 i2c_unregister_device(client: rwork->client);
143
144 kfree(objp: rwork);
145}
146
147/*
148 * This schedules removal of SMBus companion device. We have to do
149 * it in a separate tread to avoid deadlocking on psmouse_mutex in
150 * case the device has a trackstick (which is also driven by psmouse).
151 *
152 * Note that this may be racing with i2c adapter removal, but we
153 * can't do anything about that: i2c automatically destroys clients
154 * attached to an adapter that is being removed. This has to be
155 * fixed in i2c core.
156 */
157static void psmouse_smbus_schedule_remove(struct i2c_client *client)
158{
159 struct psmouse_smbus_removal_work *rwork;
160
161 rwork = kzalloc(size: sizeof(*rwork), GFP_KERNEL);
162 if (rwork) {
163 INIT_WORK(&rwork->work, psmouse_smbus_remove_i2c_device);
164 rwork->client = client;
165
166 queue_work(wq: psmouse_smbus_wq, work: &rwork->work);
167 }
168}
169
170static void psmouse_smbus_disconnect(struct psmouse *psmouse)
171{
172 struct psmouse_smbus_dev *smbdev = psmouse->private;
173
174 mutex_lock(&psmouse_smbus_mutex);
175
176 if (smbdev->dead) {
177 list_del(entry: &smbdev->node);
178 kfree(objp: smbdev);
179 } else {
180 smbdev->dead = true;
181 device_link_remove(consumer: &smbdev->client->dev,
182 supplier: &psmouse->ps2dev.serio->dev);
183 psmouse_dbg(smbdev->psmouse,
184 "posting removal request for SMBus companion %s\n",
185 dev_name(&smbdev->client->dev));
186 psmouse_smbus_schedule_remove(client: smbdev->client);
187 }
188
189 mutex_unlock(lock: &psmouse_smbus_mutex);
190
191 psmouse->private = NULL;
192}
193
194static int psmouse_smbus_create_companion(struct device *dev, void *data)
195{
196 struct psmouse_smbus_dev *smbdev = data;
197 unsigned short addr_list[] = { smbdev->board.addr, I2C_CLIENT_END };
198 struct i2c_adapter *adapter;
199 struct i2c_client *client;
200
201 adapter = i2c_verify_adapter(dev);
202 if (!adapter)
203 return 0;
204
205 if (!i2c_check_functionality(adap: adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
206 return 0;
207
208 client = i2c_new_scanned_device(adap: adapter, info: &smbdev->board,
209 addr_list, NULL);
210 if (IS_ERR(ptr: client))
211 return 0;
212
213 /* We have our(?) device, stop iterating i2c bus. */
214 smbdev->client = client;
215 return 1;
216}
217
218void psmouse_smbus_cleanup(struct psmouse *psmouse)
219{
220 struct psmouse_smbus_dev *smbdev, *tmp;
221
222 mutex_lock(&psmouse_smbus_mutex);
223
224 list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
225 if (psmouse == smbdev->psmouse) {
226 list_del(entry: &smbdev->node);
227 kfree(objp: smbdev);
228 }
229 }
230
231 mutex_unlock(lock: &psmouse_smbus_mutex);
232}
233
234int psmouse_smbus_init(struct psmouse *psmouse,
235 const struct i2c_board_info *board,
236 const void *pdata, size_t pdata_size,
237 bool need_deactivate,
238 bool leave_breadcrumbs)
239{
240 struct psmouse_smbus_dev *smbdev;
241 int error;
242
243 smbdev = kzalloc(size: sizeof(*smbdev), GFP_KERNEL);
244 if (!smbdev)
245 return -ENOMEM;
246
247 smbdev->psmouse = psmouse;
248 smbdev->board = *board;
249 smbdev->need_deactivate = need_deactivate;
250
251 if (pdata) {
252 smbdev->board.platform_data = kmemdup(p: pdata, size: pdata_size,
253 GFP_KERNEL);
254 if (!smbdev->board.platform_data) {
255 kfree(objp: smbdev);
256 return -ENOMEM;
257 }
258 }
259
260 if (need_deactivate)
261 psmouse_deactivate(psmouse);
262
263 psmouse->private = smbdev;
264 psmouse->protocol_handler = psmouse_smbus_process_byte;
265 psmouse->reconnect = psmouse_smbus_reconnect;
266 psmouse->fast_reconnect = psmouse_smbus_reconnect;
267 psmouse->disconnect = psmouse_smbus_disconnect;
268 psmouse->resync_time = 0;
269
270 mutex_lock(&psmouse_smbus_mutex);
271 list_add_tail(new: &smbdev->node, head: &psmouse_smbus_list);
272 mutex_unlock(lock: &psmouse_smbus_mutex);
273
274 /* Bind to already existing adapters right away */
275 error = i2c_for_each_dev(data: smbdev, fn: psmouse_smbus_create_companion);
276
277 if (smbdev->client) {
278 /* We have our companion device */
279 if (!device_link_add(consumer: &smbdev->client->dev,
280 supplier: &psmouse->ps2dev.serio->dev,
281 DL_FLAG_STATELESS))
282 psmouse_warn(psmouse,
283 "failed to set up link with iSMBus companion %s\n",
284 dev_name(&smbdev->client->dev));
285 return 0;
286 }
287
288 /*
289 * If we did not create i2c device we will not need platform
290 * data even if we are leaving breadcrumbs.
291 */
292 kfree(objp: smbdev->board.platform_data);
293 smbdev->board.platform_data = NULL;
294
295 if (error < 0 || !leave_breadcrumbs) {
296 mutex_lock(&psmouse_smbus_mutex);
297 list_del(entry: &smbdev->node);
298 mutex_unlock(lock: &psmouse_smbus_mutex);
299
300 kfree(objp: smbdev);
301 }
302
303 return error < 0 ? error : -EAGAIN;
304}
305
306int __init psmouse_smbus_module_init(void)
307{
308 int error;
309
310 psmouse_smbus_wq = alloc_workqueue(fmt: "psmouse-smbus", flags: 0, max_active: 0);
311 if (!psmouse_smbus_wq)
312 return -ENOMEM;
313
314 error = bus_register_notifier(bus: &i2c_bus_type, nb: &psmouse_smbus_notifier);
315 if (error) {
316 pr_err("failed to register i2c bus notifier: %d\n", error);
317 destroy_workqueue(wq: psmouse_smbus_wq);
318 return error;
319 }
320
321 return 0;
322}
323
324void psmouse_smbus_module_exit(void)
325{
326 bus_unregister_notifier(bus: &i2c_bus_type, nb: &psmouse_smbus_notifier);
327 destroy_workqueue(wq: psmouse_smbus_wq);
328}
329

source code of linux/drivers/input/mouse/psmouse-smbus.c