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/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 struct workqueue_struct *psmouse_smbus_wq;
  30
  31 static void psmouse_smbus_check_adapter(struct i2c_adapter *adapter)
  32 {
  33         struct psmouse_smbus_dev *smbdev;
  34
  35         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
  36                 return;
  37
  38         guard(mutex)(&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(smbdev->psmouse->ps2dev.serio);
  57         }
  58 }
  59
  60 static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
  61 {
  62         struct psmouse_smbus_dev *smbdev, *tmp;
  63
  64         guard(mutex)(&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                         device_link_remove(&smbdev->client->dev,
  79                                            &smbdev->psmouse->ps2dev.serio->dev);
  80                         serio_rescan(smbdev->psmouse->ps2dev.serio);
  81                 } else {
  82                         list_del(&smbdev->node);
  83                         kfree(smbdev);
  84                 }
  85         }
  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                 queue_work(psmouse_smbus_wq, &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         guard(mutex)(&psmouse_smbus_mutex);
 171
 172         if (smbdev->dead) {
 173                 list_del(&smbdev->node);
 174                 kfree(smbdev);
 175         } else {
 176                 smbdev->dead = true;
 177                 device_link_remove(&smbdev->client->dev,
 178                                    &psmouse->ps2dev.serio->dev);
 179                 psmouse_dbg(smbdev->psmouse,
 180                             "posting removal request for SMBus companion %s\n",
 181                             dev_name(&smbdev->client->dev));
 182                 psmouse_smbus_schedule_remove(smbdev->client);
 183         }
 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         guard(mutex)(&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
 226 int psmouse_smbus_init(struct psmouse *psmouse,
 227                        const struct i2c_board_info *board,
 228                        const void *pdata, size_t pdata_size,
 229                        bool need_deactivate,
 230                        bool leave_breadcrumbs)
 231 {
 232         struct psmouse_smbus_dev *smbdev;
 233         int error;
 234
 235         smbdev = kzalloc(sizeof(*smbdev), GFP_KERNEL);
 236         if (!smbdev)
 237                 return -ENOMEM;
 238
 239         smbdev->psmouse = psmouse;
 240         smbdev->board = *board;
 241         smbdev->need_deactivate = need_deactivate;
 242
 243         if (pdata) {
 244                 smbdev->board.platform_data = kmemdup(pdata, pdata_size,
 245                                                       GFP_KERNEL);
 246                 if (!smbdev->board.platform_data) {
 247                         kfree(smbdev);
 248                         return -ENOMEM;
 249                 }
 250         }
 251
 252         if (need_deactivate)
 253                 psmouse_deactivate(psmouse);
 254
 255         psmouse->private = smbdev;
 256         psmouse->protocol_handler = psmouse_smbus_process_byte;
 257         psmouse->reconnect = psmouse_smbus_reconnect;
 258         psmouse->fast_reconnect = psmouse_smbus_reconnect;
 259         psmouse->disconnect = psmouse_smbus_disconnect;
 260         psmouse->resync_time = 0;
 261
 262         scoped_guard(mutex, &psmouse_smbus_mutex) {
 263                 list_add_tail(&smbdev->node, &psmouse_smbus_list);
 264         }
 265
 266         /* Bind to already existing adapters right away */
 267         error = i2c_for_each_dev(smbdev, psmouse_smbus_create_companion);
 268
 269         if (smbdev->client) {
 270                 /* We have our companion device */
 271                 if (!device_link_add(&smbdev->client->dev,
 272                                      &psmouse->ps2dev.serio->dev,
 273                                      DL_FLAG_STATELESS))
 274                         psmouse_warn(psmouse,
 275                                      "failed to set up link with iSMBus companion %s\n",
 276                                      dev_name(&smbdev->client->dev));
 277                 return 0;
 278         }
 279
 280         /*
 281          * If we did not create i2c device we will not need platform
 282          * data even if we are leaving breadcrumbs.
 283          */
 284         kfree(smbdev->board.platform_data);
 285         smbdev->board.platform_data = NULL;
 286
 287         if (error < 0 || !leave_breadcrumbs) {
 288                 scoped_guard(mutex, &psmouse_smbus_mutex) {
 289                         list_del(&smbdev->node);
 290                 }
 291
 292                 kfree(smbdev);
 293         }
 294
 295         return error < 0 ? error : -EAGAIN;
 296 }
 297
 298 int __init psmouse_smbus_module_init(void)
 299 {
 300         int error;
 301
 302         psmouse_smbus_wq = alloc_workqueue("psmouse-smbus", 0, 0);
 303         if (!psmouse_smbus_wq)
 304                 return -ENOMEM;
 305
 306         error = bus_register_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
 307         if (error) {
 308                 pr_err("failed to register i2c bus notifier: %d\n", error);
 309                 destroy_workqueue(psmouse_smbus_wq);
 310                 return error;
 311         }
 312
 313         return 0;
 314 }
 315
 316 void psmouse_smbus_module_exit(void)
 317 {
 318         bus_unregister_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
 319         destroy_workqueue(psmouse_smbus_wq);
 320 }