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 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 }