drivers/input/mouse/psmouse-smbus.c

   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/delay.h>
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/libps2.h>
  12 #include <linux/i2c.h>
  13 #include <linux/serio.h>
  14 #include <linux/slab.h>
  15 #include <linux/workqueue.h>
  16 #include "psmouse.h"
  17
  18 struct psmouse_smbus_dev {
  19         struct i2c_board_info board;
  20         struct psmouse *psmouse;
  21         struct i2c_client *client;
  22         struct list_head node;
  23         bool dead;
  24         bool need_deactivate;
  25 };
  26
  27 static LIST_HEAD(psmouse_smbus_list);
  28 static DEFINE_MUTEX(psmouse_smbus_mutex);
  29
  30 static struct workqueue_struct *psmouse_smbus_wq;
  31
  32 static void psmouse_smbus_check_adapter(struct i2c_adapter *adapter)
  33 {
  34         struct psmouse_smbus_dev *smbdev;
  35
  36         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
  37                 return;
  38
  39         mutex_lock(&psmouse_smbus_mutex);
  40
  41         list_for_each_entry(smbdev, &psmouse_smbus_list, node) {
  42                 if (smbdev->dead)
  43                         continue;
  44
  45                 if (smbdev->client)
  46                         continue;
  47
  48                 /*
  49                  * Here would be a good place to check if device is actually
  50                  * present, but it seems that SMBus will not respond unless we
  51                  * fully reset PS/2 connection.  So cross our fingers, and try
  52                  * to switch over, hopefully our system will not have too many
  53                  * "host notify" I2C adapters.
  54                  */
  55                 psmouse_dbg(smbdev->psmouse,
  56                             "SMBus candidate adapter appeared, triggering rescan\n");
  57                 serio_rescan(smbdev->psmouse->ps2dev.serio);
  58         }
  59
  60         mutex_unlock(&psmouse_smbus_mutex);
  61 }
  62
  63 static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
  64 {
  65         struct psmouse_smbus_dev *smbdev, *tmp;
  66
  67         mutex_lock(&psmouse_smbus_mutex);
  68
  69         list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
  70                 if (smbdev->client != client)
  71                         continue;
  72
  73                 kfree(client->dev.platform_data);
  74                 client->dev.platform_data = NULL;
  75
  76                 if (!smbdev->dead) {
  77                         psmouse_dbg(smbdev->psmouse,
  78                                     "Marking SMBus companion %s as gone\n",
  79                                     dev_name(&smbdev->client->dev));
  80                         smbdev->dead = true;
  81                         device_link_remove(&smbdev->client->dev,
  82                                            &smbdev->psmouse->ps2dev.serio->dev);
  83                         serio_rescan(smbdev->psmouse->ps2dev.serio);
  84                 } else {
  85                         list_del(&smbdev->node);
  86                         kfree(smbdev);
  87                 }
  88         }
  89
  90         mutex_unlock(&psmouse_smbus_mutex);
  91 }
  92
  93 static int psmouse_smbus_notifier_call(struct notifier_block *nb,
  94                                        unsigned long action, void *data)
  95 {
  96         struct device *dev = data;
  97
  98         switch (action) {
  99         case BUS_NOTIFY_ADD_DEVICE:
 100                 if (dev->type == &i2c_adapter_type)
 101                         psmouse_smbus_check_adapter(to_i2c_adapter(dev));
 102                 break;
 103
 104         case BUS_NOTIFY_REMOVED_DEVICE:
 105                 if (dev->type == &i2c_client_type)
 106                         psmouse_smbus_detach_i2c_client(to_i2c_client(dev));
 107                 break;
 108         }
 109
 110         return 0;
 111 }
 112
 113 static struct notifier_block psmouse_smbus_notifier = {
 114         .notifier_call = psmouse_smbus_notifier_call,
 115 };
 116
 117 static psmouse_ret_t psmouse_smbus_process_byte(struct psmouse *psmouse)
 118 {
 119         return PSMOUSE_FULL_PACKET;
 120 }
 121
 122 static void psmouse_activate_smbus_mode(struct psmouse_smbus_dev *smbdev)
 123 {
 124         if (smbdev->need_deactivate) {
 125                 psmouse_deactivate(smbdev->psmouse);
 126                 /* Give the device time to switch into SMBus mode */
 127                 msleep(30);
 128         }
 129 }
 130
 131 static int psmouse_smbus_reconnect(struct psmouse *psmouse)
 132 {
 133         psmouse_activate_smbus_mode(psmouse->private);
 134         return 0;
 135 }
 136
 137 struct psmouse_smbus_removal_work {
 138         struct work_struct work;
 139         struct i2c_client *client;
 140 };
 141
 142 static void psmouse_smbus_remove_i2c_device(struct work_struct *work)
 143 {
 144         struct psmouse_smbus_removal_work *rwork =
 145                 container_of(work, struct psmouse_smbus_removal_work, work);
 146
 147         dev_dbg(&rwork->client->dev, "destroying SMBus companion device\n");
 148         i2c_unregister_device(rwork->client);
 149
 150         kfree(rwork);
 151 }
 152
 153 /*
 154  * This schedules removal of SMBus companion device. We have to do
 155  * it in a separate tread to avoid deadlocking on psmouse_mutex in
 156  * case the device has a trackstick (which is also driven by psmouse).
 157  *
 158  * Note that this may be racing with i2c adapter removal, but we
 159  * can't do anything about that: i2c automatically destroys clients
 160  * attached to an adapter that is being removed. This has to be
 161  * fixed in i2c core.
 162  */
 163 static void psmouse_smbus_schedule_remove(struct i2c_client *client)
 164 {
 165         struct psmouse_smbus_removal_work *rwork;
 166
 167         rwork = kzalloc(sizeof(*rwork), GFP_KERNEL);
 168         if (rwork) {
 169                 INIT_WORK(&rwork->work, psmouse_smbus_remove_i2c_device);
 170                 rwork->client = client;
 171
 172                 queue_work(psmouse_smbus_wq, &rwork->work);
 173         }
 174 }
 175
 176 static void psmouse_smbus_disconnect(struct psmouse *psmouse)
 177 {
 178         struct psmouse_smbus_dev *smbdev = psmouse->private;
 179
 180         mutex_lock(&psmouse_smbus_mutex);
 181
 182         if (smbdev->dead) {
 183                 list_del(&smbdev->node);
 184                 kfree(smbdev);
 185         } else {
 186                 smbdev->dead = true;
 187                 device_link_remove(&smbdev->client->dev,
 188                                    &psmouse->ps2dev.serio->dev);
 189                 psmouse_dbg(smbdev->psmouse,
 190                             "posting removal request for SMBus companion %s\n",
 191                             dev_name(&smbdev->client->dev));
 192                 psmouse_smbus_schedule_remove(smbdev->client);
 193         }
 194
 195         mutex_unlock(&psmouse_smbus_mutex);
 196
 197         psmouse->private = NULL;
 198 }
 199
 200 static int psmouse_smbus_create_companion(struct device *dev, void *data)
 201 {
 202         struct psmouse_smbus_dev *smbdev = data;
 203         unsigned short addr_list[] = { smbdev->board.addr, I2C_CLIENT_END };
 204         struct i2c_adapter *adapter;
 205         struct i2c_client *client;
 206
 207         adapter = i2c_verify_adapter(dev);
 208         if (!adapter)
 209                 return 0;
 210
 211         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
 212                 return 0;
 213
 214         client = i2c_new_scanned_device(adapter, &smbdev->board,
 215                                         addr_list, NULL);
 216         if (IS_ERR(client))
 217                 return 0;
 218
 219         /* We have our(?) device, stop iterating i2c bus. */
 220         smbdev->client = client;
 221         return 1;
 222 }
 223
 224 void psmouse_smbus_cleanup(struct psmouse *psmouse)
 225 {
 226         struct psmouse_smbus_dev *smbdev, *tmp;
 227
 228         mutex_lock(&psmouse_smbus_mutex);
 229
 230         list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
 231                 if (psmouse == smbdev->psmouse) {
 232                         list_del(&smbdev->node);
 233                         kfree(smbdev);
 234                 }
 235         }
 236
 237         mutex_unlock(&psmouse_smbus_mutex);
 238 }
 239
 240 int psmouse_smbus_init(struct psmouse *psmouse,
 241                        const struct i2c_board_info *board,
 242                        const void *pdata, size_t pdata_size,
 243                        bool need_deactivate,
 244                        bool leave_breadcrumbs)
 245 {
 246         struct psmouse_smbus_dev *smbdev;
 247         int error;
 248
 249         smbdev = kzalloc(sizeof(*smbdev), GFP_KERNEL);
 250         if (!smbdev)
 251                 return -ENOMEM;
 252
 253         smbdev->psmouse = psmouse;
 254         smbdev->board = *board;
 255         smbdev->need_deactivate = need_deactivate;
 256
 257         if (pdata) {
 258                 smbdev->board.platform_data = kmemdup(pdata, pdata_size,
 259                                                       GFP_KERNEL);
 260                 if (!smbdev->board.platform_data) {
 261                         kfree(smbdev);
 262                         return -ENOMEM;
 263                 }
 264         }
 265
 266         psmouse_activate_smbus_mode(smbdev);
 267
 268         psmouse->private = smbdev;
 269         psmouse->protocol_handler = psmouse_smbus_process_byte;
 270         psmouse->reconnect = psmouse_smbus_reconnect;
 271         psmouse->fast_reconnect = psmouse_smbus_reconnect;
 272         psmouse->disconnect = psmouse_smbus_disconnect;
 273         psmouse->resync_time = 0;
 274
 275         mutex_lock(&psmouse_smbus_mutex);
 276         list_add_tail(&smbdev->node, &psmouse_smbus_list);
 277         mutex_unlock(&psmouse_smbus_mutex);
 278
 279         /* Bind to already existing adapters right away */
 280         error = i2c_for_each_dev(smbdev, psmouse_smbus_create_companion);
 281
 282         if (smbdev->client) {
 283                 /* We have our companion device */
 284                 if (!device_link_add(&smbdev->client->dev,
 285                                      &psmouse->ps2dev.serio->dev,
 286                                      DL_FLAG_STATELESS))
 287                         psmouse_warn(psmouse,
 288                                      "failed to set up link with iSMBus companion %s\n",
 289                                      dev_name(&smbdev->client->dev));
 290                 return 0;
 291         }
 292
 293         /*
 294          * If we did not create i2c device we will not need platform
 295          * data even if we are leaving breadcrumbs.
 296          */
 297         kfree(smbdev->board.platform_data);
 298         smbdev->board.platform_data = NULL;
 299
 300         if (error < 0 || !leave_breadcrumbs) {
 301                 mutex_lock(&psmouse_smbus_mutex);
 302                 list_del(&smbdev->node);
 303                 mutex_unlock(&psmouse_smbus_mutex);
 304
 305                 kfree(smbdev);
 306         }
 307
 308         return error < 0 ? error : -EAGAIN;
 309 }
 310
 311 int __init psmouse_smbus_module_init(void)
 312 {
 313         int error;
 314
 315         psmouse_smbus_wq = alloc_workqueue("psmouse-smbus", 0, 0);
 316         if (!psmouse_smbus_wq)
 317                 return -ENOMEM;
 318
 319         error = bus_register_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
 320         if (error) {
 321                 pr_err("failed to register i2c bus notifier: %d\n", error);
 322                 destroy_workqueue(psmouse_smbus_wq);
 323                 return error;
 324         }
 325
 326         return 0;
 327 }
 328
 329 void psmouse_smbus_module_exit(void)
 330 {
 331         bus_unregister_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
 332         destroy_workqueue(psmouse_smbus_wq);
 333 }