drivers/input/mouse/psmouse-smbus.c

   1 /*
   2  * Copyright (c) 2017 Red Hat, Inc
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 as published by
   6  * the Free Software Foundation.
   7  */
   8
   9 #define pr_fmt(fmt)             KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/libps2.h>
  14 #include <linux/i2c.h>
  15 #include <linux/serio.h>
  16 #include <linux/slab.h>
  17 #include <linux/workqueue.h>
  18 #include "psmouse.h"
  19
  20 struct psmouse_smbus_dev {
  21         struct i2c_board_info board;
  22         struct psmouse *psmouse;
  23         struct i2c_client *client;
  24         struct list_head node;
  25         bool dead;
  26         bool need_deactivate;
  27 };
  28
  29 static LIST_HEAD(psmouse_smbus_list);
  30 static DEFINE_MUTEX(psmouse_smbus_mutex);
  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                         serio_rescan(smbdev->psmouse->ps2dev.serio);
  82                 } else {
  83                         list_del(&smbdev->node);
  84                         kfree(smbdev);
  85                 }
  86         }
  87
  88         mutex_unlock(&psmouse_smbus_mutex);
  89 }
  90
  91 static int psmouse_smbus_notifier_call(struct notifier_block *nb,
  92                                        unsigned long action, void *data)
  93 {
  94         struct device *dev = data;
  95
  96         switch (action) {
  97         case BUS_NOTIFY_ADD_DEVICE:
  98                 if (dev->type == &i2c_adapter_type)
  99                         psmouse_smbus_check_adapter(to_i2c_adapter(dev));
 100                 break;
 101
 102         case BUS_NOTIFY_REMOVED_DEVICE:
 103                 if (dev->type == &i2c_client_type)
 104                         psmouse_smbus_detach_i2c_client(to_i2c_client(dev));
 105                 break;
 106         }
 107
 108         return 0;
 109 }
 110
 111 static struct notifier_block psmouse_smbus_notifier = {
 112         .notifier_call = psmouse_smbus_notifier_call,
 113 };
 114
 115 static psmouse_ret_t psmouse_smbus_process_byte(struct psmouse *psmouse)
 116 {
 117         return PSMOUSE_FULL_PACKET;
 118 }
 119
 120 static int psmouse_smbus_reconnect(struct psmouse *psmouse)
 121 {
 122         struct psmouse_smbus_dev *smbdev = psmouse->private;
 123
 124         if (smbdev->need_deactivate)
 125                 psmouse_deactivate(psmouse);
 126
 127         return 0;
 128 }
 129
 130 struct psmouse_smbus_removal_work {
 131         struct work_struct work;
 132         struct i2c_client *client;
 133 };
 134
 135 static void psmouse_smbus_remove_i2c_device(struct work_struct *work)
 136 {
 137         struct psmouse_smbus_removal_work *rwork =
 138                 container_of(work, struct psmouse_smbus_removal_work, work);
 139
 140         dev_dbg(&rwork->client->dev, "destroying SMBus companion device\n");
 141         i2c_unregister_device(rwork->client);
 142
 143         kfree(rwork);
 144 }
 145
 146 /*
 147  * This schedules removal of SMBus companion device. We have to do
 148  * it in a separate tread to avoid deadlocking on psmouse_mutex in
 149  * case the device has a trackstick (which is also driven by psmouse).
 150  *
 151  * Note that this may be racing with i2c adapter removal, but we
 152  * can't do anything about that: i2c automatically destroys clients
 153  * attached to an adapter that is being removed. This has to be
 154  * fixed in i2c core.
 155  */
 156 static void psmouse_smbus_schedule_remove(struct i2c_client *client)
 157 {
 158         struct psmouse_smbus_removal_work *rwork;
 159
 160         rwork = kzalloc(sizeof(*rwork), GFP_KERNEL);
 161         if (rwork) {
 162                 INIT_WORK(&rwork->work, psmouse_smbus_remove_i2c_device);
 163                 rwork->client = client;
 164
 165                 schedule_work(&rwork->work);
 166         }
 167 }
 168
 169 static void psmouse_smbus_disconnect(struct psmouse *psmouse)
 170 {
 171         struct psmouse_smbus_dev *smbdev = psmouse->private;
 172
 173         mutex_lock(&psmouse_smbus_mutex);
 174
 175         if (smbdev->dead) {
 176                 list_del(&smbdev->node);
 177                 kfree(smbdev);
 178         } else {
 179                 smbdev->dead = true;
 180                 psmouse_dbg(smbdev->psmouse,
 181                             "posting removal request for SMBus companion %s\n",
 182                             dev_name(&smbdev->client->dev));
 183                 psmouse_smbus_schedule_remove(smbdev->client);
 184         }
 185
 186         mutex_unlock(&psmouse_smbus_mutex);
 187
 188         psmouse->private = NULL;
 189 }
 190
 191 static int psmouse_smbus_create_companion(struct device *dev, void *data)
 192 {
 193         struct psmouse_smbus_dev *smbdev = data;
 194         unsigned short addr_list[] = { smbdev->board.addr, I2C_CLIENT_END };
 195         struct i2c_adapter *adapter;
 196
 197         adapter = i2c_verify_adapter(dev);
 198         if (!adapter)
 199                 return 0;
 200
 201         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
 202                 return 0;
 203
 204         smbdev->client = i2c_new_probed_device(adapter, &smbdev->board,
 205                                                addr_list, NULL);
 206         if (!smbdev->client)
 207                 return 0;
 208
 209         /* We have our(?) device, stop iterating i2c bus. */
 210         return 1;
 211 }
 212
 213 void psmouse_smbus_cleanup(struct psmouse *psmouse)
 214 {
 215         struct psmouse_smbus_dev *smbdev, *tmp;
 216
 217         mutex_lock(&psmouse_smbus_mutex);
 218
 219         list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
 220                 if (psmouse == smbdev->psmouse) {
 221                         list_del(&smbdev->node);
 222                         kfree(smbdev);
 223                 }
 224         }
 225
 226         mutex_unlock(&psmouse_smbus_mutex);
 227 }
 228
 229 int psmouse_smbus_init(struct psmouse *psmouse,
 230                        const struct i2c_board_info *board,
 231                        const void *pdata, size_t pdata_size,
 232                        bool need_deactivate,
 233                        bool leave_breadcrumbs)
 234 {
 235         struct psmouse_smbus_dev *smbdev;
 236         int error;
 237
 238         smbdev = kzalloc(sizeof(*smbdev), GFP_KERNEL);
 239         if (!smbdev)
 240                 return -ENOMEM;
 241
 242         smbdev->psmouse = psmouse;
 243         smbdev->board = *board;
 244         smbdev->need_deactivate = need_deactivate;
 245
 246         if (pdata) {
 247                 smbdev->board.platform_data = kmemdup(pdata, pdata_size,
 248                                                       GFP_KERNEL);
 249                 if (!smbdev->board.platform_data) {
 250                         kfree(smbdev);
 251                         return -ENOMEM;
 252                 }
 253         }
 254
 255         if (need_deactivate)
 256                 psmouse_deactivate(psmouse);
 257
 258         psmouse->private = smbdev;
 259         psmouse->protocol_handler = psmouse_smbus_process_byte;
 260         psmouse->reconnect = psmouse_smbus_reconnect;
 261         psmouse->fast_reconnect = psmouse_smbus_reconnect;
 262         psmouse->disconnect = psmouse_smbus_disconnect;
 263         psmouse->resync_time = 0;
 264
 265         mutex_lock(&psmouse_smbus_mutex);
 266         list_add_tail(&smbdev->node, &psmouse_smbus_list);
 267         mutex_unlock(&psmouse_smbus_mutex);
 268
 269         /* Bind to already existing adapters right away */
 270         error = i2c_for_each_dev(smbdev, psmouse_smbus_create_companion);
 271
 272         if (smbdev->client) {
 273                 /* We have our companion device */
 274                 return 0;
 275         }
 276
 277         /*
 278          * If we did not create i2c device we will not need platform
 279          * data even if we are leaving breadcrumbs.
 280          */
 281         kfree(smbdev->board.platform_data);
 282         smbdev->board.platform_data = NULL;
 283
 284         if (error < 0 || !leave_breadcrumbs) {
 285                 mutex_lock(&psmouse_smbus_mutex);
 286                 list_del(&smbdev->node);
 287                 mutex_unlock(&psmouse_smbus_mutex);
 288
 289                 kfree(smbdev);
 290         }
 291
 292         return error < 0 ? error : -EAGAIN;
 293 }
 294
 295 int __init psmouse_smbus_module_init(void)
 296 {
 297         int error;
 298
 299         error = bus_register_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
 300         if (error) {
 301                 pr_err("failed to register i2c bus notifier: %d\n", error);
 302                 return error;
 303         }
 304
 305         return 0;
 306 }
 307
 308 void psmouse_smbus_module_exit(void)
 309 {
 310         bus_unregister_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
 311         flush_scheduled_work();
 312 }