drivers/platform/chrome/cros_ec_dev.c

   1 /*
   2  * cros_ec_dev - expose the Chrome OS Embedded Controller to user-space
   3  *
   4  * Copyright (C) 2014 Google, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/fs.h>
  21 #include <linux/module.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/slab.h>
  24 #include <linux/uaccess.h>
  25
  26 #include "cros_ec_dev.h"
  27
  28 /* Device variables */
  29 #define CROS_MAX_DEV 128
  30 static int ec_major;
  31
  32 static const struct attribute_group *cros_ec_groups[] = {
  33         &cros_ec_attr_group,
  34         &cros_ec_lightbar_attr_group,
  35         &cros_ec_vbc_attr_group,
  36         NULL,
  37 };
  38
  39 static struct class cros_class = {
  40         .owner          = THIS_MODULE,
  41         .name           = "chromeos",
  42         .dev_groups     = cros_ec_groups,
  43 };
  44
  45 /* Basic communication */
  46 static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
  47 {
  48         struct ec_response_get_version *resp;
  49         static const char * const current_image_name[] = {
  50                 "unknown", "read-only", "read-write", "invalid",
  51         };
  52         struct cros_ec_command *msg;
  53         int ret;
  54
  55         msg = kmalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
  56         if (!msg)
  57                 return -ENOMEM;
  58
  59         msg->version = 0;
  60         msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
  61         msg->insize = sizeof(*resp);
  62         msg->outsize = 0;
  63
  64         ret = cros_ec_cmd_xfer(ec->ec_dev, msg);
  65         if (ret < 0)
  66                 goto exit;
  67
  68         if (msg->result != EC_RES_SUCCESS) {
  69                 snprintf(str, maxlen,
  70                          "%s\nUnknown EC version: EC returned %d\n",
  71                          CROS_EC_DEV_VERSION, msg->result);
  72                 ret = -EINVAL;
  73                 goto exit;
  74         }
  75
  76         resp = (struct ec_response_get_version *)msg->data;
  77         if (resp->current_image >= ARRAY_SIZE(current_image_name))
  78                 resp->current_image = 3; /* invalid */
  79
  80         snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
  81                  resp->version_string_ro, resp->version_string_rw,
  82                  current_image_name[resp->current_image]);
  83
  84         ret = 0;
  85 exit:
  86         kfree(msg);
  87         return ret;
  88 }
  89
  90 /* Device file ops */
  91 static int ec_device_open(struct inode *inode, struct file *filp)
  92 {
  93         struct cros_ec_dev *ec = container_of(inode->i_cdev,
  94                                               struct cros_ec_dev, cdev);
  95         filp->private_data = ec;
  96         nonseekable_open(inode, filp);
  97         return 0;
  98 }
  99
 100 static int ec_device_release(struct inode *inode, struct file *filp)
 101 {
 102         return 0;
 103 }
 104
 105 static ssize_t ec_device_read(struct file *filp, char __user *buffer,
 106                               size_t length, loff_t *offset)
 107 {
 108         struct cros_ec_dev *ec = filp->private_data;
 109         char msg[sizeof(struct ec_response_get_version) +
 110                  sizeof(CROS_EC_DEV_VERSION)];
 111         size_t count;
 112         int ret;
 113
 114         if (*offset != 0)
 115                 return 0;
 116
 117         ret = ec_get_version(ec, msg, sizeof(msg));
 118         if (ret)
 119                 return ret;
 120
 121         count = min(length, strlen(msg));
 122
 123         if (copy_to_user(buffer, msg, count))
 124                 return -EFAULT;
 125
 126         *offset = count;
 127         return count;
 128 }
 129
 130 /* Ioctls */
 131 static long ec_device_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
 132 {
 133         long ret;
 134         struct cros_ec_command u_cmd;
 135         struct cros_ec_command *s_cmd;
 136
 137         if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
 138                 return -EFAULT;
 139
 140         s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
 141                         GFP_KERNEL);
 142         if (!s_cmd)
 143                 return -ENOMEM;
 144
 145         if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
 146                 ret = -EFAULT;
 147                 goto exit;
 148         }
 149
 150         s_cmd->command += ec->cmd_offset;
 151         ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
 152         /* Only copy data to userland if data was received. */
 153         if (ret < 0)
 154                 goto exit;
 155
 156         if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize))
 157                 ret = -EFAULT;
 158 exit:
 159         kfree(s_cmd);
 160         return ret;
 161 }
 162
 163 static long ec_device_ioctl_readmem(struct cros_ec_dev *ec, void __user *arg)
 164 {
 165         struct cros_ec_device *ec_dev = ec->ec_dev;
 166         struct cros_ec_readmem s_mem = { };
 167         long num;
 168
 169         /* Not every platform supports direct reads */
 170         if (!ec_dev->cmd_readmem)
 171                 return -ENOTTY;
 172
 173         if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
 174                 return -EFAULT;
 175
 176         num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
 177                                   s_mem.buffer);
 178         if (num <= 0)
 179                 return num;
 180
 181         if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
 182                 return -EFAULT;
 183
 184         return 0;
 185 }
 186
 187 static long ec_device_ioctl(struct file *filp, unsigned int cmd,
 188                             unsigned long arg)
 189 {
 190         struct cros_ec_dev *ec = filp->private_data;
 191
 192         if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
 193                 return -ENOTTY;
 194
 195         switch (cmd) {
 196         case CROS_EC_DEV_IOCXCMD:
 197                 return ec_device_ioctl_xcmd(ec, (void __user *)arg);
 198         case CROS_EC_DEV_IOCRDMEM:
 199                 return ec_device_ioctl_readmem(ec, (void __user *)arg);
 200         }
 201
 202         return -ENOTTY;
 203 }
 204
 205 /* Module initialization */
 206 static const struct file_operations fops = {
 207         .open = ec_device_open,
 208         .release = ec_device_release,
 209         .read = ec_device_read,
 210         .unlocked_ioctl = ec_device_ioctl,
 211 };
 212
 213 static void __remove(struct device *dev)
 214 {
 215         struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
 216                                               class_dev);
 217         kfree(ec);
 218 }
 219
 220 static int ec_device_probe(struct platform_device *pdev)
 221 {
 222         int retval = -ENOMEM;
 223         struct device *dev = &pdev->dev;
 224         struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
 225         dev_t devno = MKDEV(ec_major, pdev->id);
 226         struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
 227
 228         if (!ec)
 229                 return retval;
 230
 231         dev_set_drvdata(dev, ec);
 232         ec->ec_dev = dev_get_drvdata(dev->parent);
 233         ec->dev = dev;
 234         ec->cmd_offset = ec_platform->cmd_offset;
 235         device_initialize(&ec->class_dev);
 236         cdev_init(&ec->cdev, &fops);
 237
 238         /*
 239          * Add the character device
 240          * Link cdev to the class device to be sure device is not used
 241          * before unbinding it.
 242          */
 243         ec->cdev.kobj.parent = &ec->class_dev.kobj;
 244         retval = cdev_add(&ec->cdev, devno, 1);
 245         if (retval) {
 246                 dev_err(dev, ": failed to add character device\n");
 247                 goto cdev_add_failed;
 248         }
 249
 250         /*
 251          * Add the class device
 252          * Link to the character device for creating the /dev entry
 253          * in devtmpfs.
 254          */
 255         ec->class_dev.devt = ec->cdev.dev;
 256         ec->class_dev.class = &cros_class;
 257         ec->class_dev.parent = dev;
 258         ec->class_dev.release = __remove;
 259
 260         retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
 261         if (retval) {
 262                 dev_err(dev, "dev_set_name failed => %d\n", retval);
 263                 goto set_named_failed;
 264         }
 265
 266         retval = device_add(&ec->class_dev);
 267         if (retval) {
 268                 dev_err(dev, "device_register failed => %d\n", retval);
 269                 goto dev_reg_failed;
 270         }
 271
 272         return 0;
 273
 274 dev_reg_failed:
 275 set_named_failed:
 276         dev_set_drvdata(dev, NULL);
 277         cdev_del(&ec->cdev);
 278 cdev_add_failed:
 279         kfree(ec);
 280         return retval;
 281 }
 282
 283 static int ec_device_remove(struct platform_device *pdev)
 284 {
 285         struct cros_ec_dev *ec = dev_get_drvdata(&pdev->dev);
 286         cdev_del(&ec->cdev);
 287         device_unregister(&ec->class_dev);
 288         return 0;
 289 }
 290
 291 static const struct platform_device_id cros_ec_id[] = {
 292         { "cros-ec-ctl", 0 },
 293         { /* sentinel */ },
 294 };
 295 MODULE_DEVICE_TABLE(platform, cros_ec_id);
 296
 297 static struct platform_driver cros_ec_dev_driver = {
 298         .driver = {
 299                 .name = "cros-ec-ctl",
 300         },
 301         .probe = ec_device_probe,
 302         .remove = ec_device_remove,
 303 };
 304
 305 static int __init cros_ec_dev_init(void)
 306 {
 307         int ret;
 308         dev_t dev = 0;
 309
 310         ret  = class_register(&cros_class);
 311         if (ret) {
 312                 pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
 313                 return ret;
 314         }
 315
 316         /* Get a range of minor numbers (starting with 0) to work with */
 317         ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
 318         if (ret < 0) {
 319                 pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
 320                 goto failed_chrdevreg;
 321         }
 322         ec_major = MAJOR(dev);
 323
 324         /* Register the driver */
 325         ret = platform_driver_register(&cros_ec_dev_driver);
 326         if (ret < 0) {
 327                 pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
 328                 goto failed_devreg;
 329         }
 330         return 0;
 331
 332 failed_devreg:
 333         unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
 334 failed_chrdevreg:
 335         class_unregister(&cros_class);
 336         return ret;
 337 }
 338
 339 static void __exit cros_ec_dev_exit(void)
 340 {
 341         platform_driver_unregister(&cros_ec_dev_driver);
 342         unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
 343         class_unregister(&cros_class);
 344 }
 345
 346 module_init(cros_ec_dev_init);
 347 module_exit(cros_ec_dev_exit);
 348
 349 MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
 350 MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
 351 MODULE_VERSION("1.0");
 352 MODULE_LICENSE("GPL");