drivers/platform/chrome/cros_ec_chardev.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Miscellaneous character driver for ChromeOS Embedded Controller
   4  *
   5  * Copyright 2014 Google, Inc.
   6  * Copyright 2019 Google LLC
   7  *
   8  * This file is a rework and part of the code is ported from
   9  * drivers/mfd/cros_ec_dev.c that was originally written by
  10  * Bill Richardson.
  11  */
  12
  13 #include <linux/init.h>
  14 #include <linux/device.h>
  15 #include <linux/fs.h>
  16 #include <linux/miscdevice.h>
  17 #include <linux/module.h>
  18 #include <linux/notifier.h>
  19 #include <linux/platform_data/cros_ec_chardev.h>
  20 #include <linux/platform_data/cros_ec_commands.h>
  21 #include <linux/platform_data/cros_ec_proto.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/poll.h>
  24 #include <linux/slab.h>
  25 #include <linux/types.h>
  26 #include <linux/uaccess.h>
  27
  28 #define DRV_NAME                "cros-ec-chardev"
  29
  30 /* Arbitrary bounded size for the event queue */
  31 #define CROS_MAX_EVENT_LEN      PAGE_SIZE
  32
  33 struct chardev_data {
  34         struct cros_ec_dev *ec_dev;
  35         struct miscdevice misc;
  36 };
  37
  38 struct chardev_priv {
  39         struct cros_ec_dev *ec_dev;
  40         struct notifier_block notifier;
  41         wait_queue_head_t wait_event;
  42         unsigned long event_mask;
  43         struct list_head events;
  44         size_t event_len;
  45 };
  46
  47 struct ec_event {
  48         struct list_head node;
  49         size_t size;
  50         u8 event_type;
  51         u8 data[];
  52 };
  53
  54 static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
  55 {
  56         static const char * const current_image_name[] = {
  57                 "unknown", "read-only", "read-write", "invalid",
  58         };
  59         struct ec_response_get_version *resp;
  60         struct cros_ec_command *msg;
  61         int ret;
  62
  63         msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
  64         if (!msg)
  65                 return -ENOMEM;
  66
  67         msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
  68         msg->insize = sizeof(*resp);
  69
  70         ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
  71         if (ret < 0) {
  72                 snprintf(str, maxlen,
  73                          "Unknown EC version, returned error: %d\n",
  74                          msg->result);
  75                 goto exit;
  76         }
  77
  78         resp = (struct ec_response_get_version *)msg->data;
  79         if (resp->current_image >= ARRAY_SIZE(current_image_name))
  80                 resp->current_image = 3; /* invalid */
  81
  82         snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
  83                  resp->version_string_ro, resp->version_string_rw,
  84                  current_image_name[resp->current_image]);
  85
  86         ret = 0;
  87 exit:
  88         kfree(msg);
  89         return ret;
  90 }
  91
  92 static int cros_ec_chardev_mkbp_event(struct notifier_block *nb,
  93                                       unsigned long queued_during_suspend,
  94                                       void *_notify)
  95 {
  96         struct chardev_priv *priv = container_of(nb, struct chardev_priv,
  97                                                  notifier);
  98         struct cros_ec_device *ec_dev = priv->ec_dev->ec_dev;
  99         struct ec_event *event;
 100         unsigned long event_bit = 1 << ec_dev->event_data.event_type;
 101         int total_size = sizeof(*event) + ec_dev->event_size;
 102
 103         if (!(event_bit & priv->event_mask) ||
 104             (priv->event_len + total_size) > CROS_MAX_EVENT_LEN)
 105                 return NOTIFY_DONE;
 106
 107         event = kzalloc(total_size, GFP_KERNEL);
 108         if (!event)
 109                 return NOTIFY_DONE;
 110
 111         event->size = ec_dev->event_size;
 112         event->event_type = ec_dev->event_data.event_type;
 113         memcpy(event->data, &ec_dev->event_data.data, ec_dev->event_size);
 114
 115         spin_lock(&priv->wait_event.lock);
 116         list_add_tail(&event->node, &priv->events);
 117         priv->event_len += total_size;
 118         wake_up_locked(&priv->wait_event);
 119         spin_unlock(&priv->wait_event.lock);
 120
 121         return NOTIFY_OK;
 122 }
 123
 124 static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv,
 125                                                     bool fetch, bool block)
 126 {
 127         struct ec_event *event;
 128         int err;
 129
 130         spin_lock(&priv->wait_event.lock);
 131         if (!block && list_empty(&priv->events)) {
 132                 event = ERR_PTR(-EWOULDBLOCK);
 133                 goto out;
 134         }
 135
 136         if (!fetch) {
 137                 event = NULL;
 138                 goto out;
 139         }
 140
 141         err = wait_event_interruptible_locked(priv->wait_event,
 142                                               !list_empty(&priv->events));
 143         if (err) {
 144                 event = ERR_PTR(err);
 145                 goto out;
 146         }
 147
 148         event = list_first_entry(&priv->events, struct ec_event, node);
 149         list_del(&event->node);
 150         priv->event_len -= sizeof(*event) + event->size;
 151
 152 out:
 153         spin_unlock(&priv->wait_event.lock);
 154         return event;
 155 }
 156
 157 /*
 158  * Device file ops
 159  */
 160 static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
 161 {
 162         struct miscdevice *mdev = filp->private_data;
 163         struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent);
 164         struct chardev_priv *priv;
 165         int ret;
 166
 167         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 168         if (!priv)
 169                 return -ENOMEM;
 170
 171         priv->ec_dev = ec_dev;
 172         filp->private_data = priv;
 173         INIT_LIST_HEAD(&priv->events);
 174         init_waitqueue_head(&priv->wait_event);
 175         nonseekable_open(inode, filp);
 176
 177         priv->notifier.notifier_call = cros_ec_chardev_mkbp_event;
 178         ret = blocking_notifier_chain_register(&ec_dev->ec_dev->event_notifier,
 179                                                &priv->notifier);
 180         if (ret) {
 181                 dev_err(ec_dev->dev, "failed to register event notifier\n");
 182                 kfree(priv);
 183         }
 184
 185         return ret;
 186 }
 187
 188 static __poll_t cros_ec_chardev_poll(struct file *filp, poll_table *wait)
 189 {
 190         struct chardev_priv *priv = filp->private_data;
 191
 192         poll_wait(filp, &priv->wait_event, wait);
 193
 194         if (list_empty(&priv->events))
 195                 return 0;
 196
 197         return EPOLLIN | EPOLLRDNORM;
 198 }
 199
 200 static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,
 201                                      size_t length, loff_t *offset)
 202 {
 203         char msg[sizeof(struct ec_response_get_version) +
 204                  sizeof(CROS_EC_DEV_VERSION)];
 205         struct chardev_priv *priv = filp->private_data;
 206         struct cros_ec_dev *ec_dev = priv->ec_dev;
 207         size_t count;
 208         int ret;
 209
 210         if (priv->event_mask) { /* queued MKBP event */
 211                 struct ec_event *event;
 212
 213                 event = cros_ec_chardev_fetch_event(priv, length != 0,
 214                                                 !(filp->f_flags & O_NONBLOCK));
 215                 if (IS_ERR(event))
 216                         return PTR_ERR(event);
 217                 /*
 218                  * length == 0 is special - no IO is done but we check
 219                  * for error conditions.
 220                  */
 221                 if (length == 0)
 222                         return 0;
 223
 224                 /* The event is 1 byte of type plus the payload */
 225                 count = min(length, event->size + 1);
 226                 ret = copy_to_user(buffer, &event->event_type, count);
 227                 kfree(event);
 228                 if (ret) /* the copy failed */
 229                         return -EFAULT;
 230                 *offset = count;
 231                 return count;
 232         }
 233
 234         /*
 235          * Legacy behavior if no event mask is defined
 236          */
 237         if (*offset != 0)
 238                 return 0;
 239
 240         ret = ec_get_version(ec_dev, msg, sizeof(msg));
 241         if (ret)
 242                 return ret;
 243
 244         count = min(length, strlen(msg));
 245
 246         if (copy_to_user(buffer, msg, count))
 247                 return -EFAULT;
 248
 249         *offset = count;
 250         return count;
 251 }
 252
 253 static int cros_ec_chardev_release(struct inode *inode, struct file *filp)
 254 {
 255         struct chardev_priv *priv = filp->private_data;
 256         struct cros_ec_dev *ec_dev = priv->ec_dev;
 257         struct ec_event *event, *e;
 258
 259         blocking_notifier_chain_unregister(&ec_dev->ec_dev->event_notifier,
 260                                            &priv->notifier);
 261
 262         list_for_each_entry_safe(event, e, &priv->events, node) {
 263                 list_del(&event->node);
 264                 kfree(event);
 265         }
 266         kfree(priv);
 267
 268         return 0;
 269 }
 270
 271 /*
 272  * Ioctls
 273  */
 274 static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
 275 {
 276         struct cros_ec_command *s_cmd;
 277         struct cros_ec_command u_cmd;
 278         long ret;
 279
 280         if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
 281                 return -EFAULT;
 282
 283         if (u_cmd.outsize > EC_MAX_MSG_BYTES ||
 284             u_cmd.insize > EC_MAX_MSG_BYTES)
 285                 return -EINVAL;
 286
 287         s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
 288                         GFP_KERNEL);
 289         if (!s_cmd)
 290                 return -ENOMEM;
 291
 292         if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
 293                 ret = -EFAULT;
 294                 goto exit;
 295         }
 296
 297         if (u_cmd.outsize != s_cmd->outsize ||
 298             u_cmd.insize != s_cmd->insize) {
 299                 ret = -EINVAL;
 300                 goto exit;
 301         }
 302
 303         s_cmd->command += ec->cmd_offset;
 304         ret = cros_ec_cmd_xfer_status(ec->ec_dev, s_cmd);
 305         /* Only copy data to userland if data was received. */
 306         if (ret < 0)
 307                 goto exit;
 308
 309         if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))
 310                 ret = -EFAULT;
 311 exit:
 312         kfree(s_cmd);
 313         return ret;
 314 }
 315
 316 static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec,
 317                                            void __user *arg)
 318 {
 319         struct cros_ec_device *ec_dev = ec->ec_dev;
 320         struct cros_ec_readmem s_mem = { };
 321         long num;
 322
 323         /* Not every platform supports direct reads */
 324         if (!ec_dev->cmd_readmem)
 325                 return -ENOTTY;
 326
 327         if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
 328                 return -EFAULT;
 329
 330         num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
 331                                   s_mem.buffer);
 332         if (num <= 0)
 333                 return num;
 334
 335         if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
 336                 return -EFAULT;
 337
 338         return num;
 339 }
 340
 341 static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,
 342                                    unsigned long arg)
 343 {
 344         struct chardev_priv *priv = filp->private_data;
 345         struct cros_ec_dev *ec = priv->ec_dev;
 346
 347         if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
 348                 return -ENOTTY;
 349
 350         switch (cmd) {
 351         case CROS_EC_DEV_IOCXCMD:
 352                 return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);
 353         case CROS_EC_DEV_IOCRDMEM:
 354                 return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);
 355         case CROS_EC_DEV_IOCEVENTMASK:
 356                 priv->event_mask = arg;
 357                 return 0;
 358         }
 359
 360         return -ENOTTY;
 361 }
 362
 363 static const struct file_operations chardev_fops = {
 364         .open           = cros_ec_chardev_open,
 365         .poll           = cros_ec_chardev_poll,
 366         .read           = cros_ec_chardev_read,
 367         .release        = cros_ec_chardev_release,
 368         .unlocked_ioctl = cros_ec_chardev_ioctl,
 369 #ifdef CONFIG_COMPAT
 370         .compat_ioctl   = cros_ec_chardev_ioctl,
 371 #endif
 372 };
 373
 374 static int cros_ec_chardev_probe(struct platform_device *pdev)
 375 {
 376         struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
 377         struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
 378         struct chardev_data *data;
 379
 380         /* Create a char device: we want to create it anew */
 381         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 382         if (!data)
 383                 return -ENOMEM;
 384
 385         data->ec_dev = ec_dev;
 386         data->misc.minor = MISC_DYNAMIC_MINOR;
 387         data->misc.fops = &chardev_fops;
 388         data->misc.name = ec_platform->ec_name;
 389         data->misc.parent = pdev->dev.parent;
 390
 391         dev_set_drvdata(&pdev->dev, data);
 392
 393         return misc_register(&data->misc);
 394 }
 395
 396 static int cros_ec_chardev_remove(struct platform_device *pdev)
 397 {
 398         struct chardev_data *data = dev_get_drvdata(&pdev->dev);
 399
 400         misc_deregister(&data->misc);
 401
 402         return 0;
 403 }
 404
 405 static struct platform_driver cros_ec_chardev_driver = {
 406         .driver = {
 407                 .name = DRV_NAME,
 408         },
 409         .probe = cros_ec_chardev_probe,
 410         .remove = cros_ec_chardev_remove,
 411 };
 412
 413 module_platform_driver(cros_ec_chardev_driver);
 414
 415 MODULE_ALIAS("platform:" DRV_NAME);
 416 MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
 417 MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver");
 418 MODULE_LICENSE("GPL");