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