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         if (u_cmd.outsize != s_cmd->outsize ||
 151             u_cmd.insize != s_cmd->insize) {
 152                 ret = -EINVAL;
 153                 goto exit;
 154         }
 155
 156         s_cmd->command += ec->cmd_offset;
 157         ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
 158         /* Only copy data to userland if data was received. */
 159         if (ret < 0)
 160                 goto exit;
 161
 162         if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))
 163                 ret = -EFAULT;
 164 exit:
 165         kfree(s_cmd);
 166         return ret;
 167 }
 168
 169 static long ec_device_ioctl_readmem(struct cros_ec_dev *ec, void __user *arg)
 170 {
 171         struct cros_ec_device *ec_dev = ec->ec_dev;
 172         struct cros_ec_readmem s_mem = { };
 173         long num;
 174
 175         /* Not every platform supports direct reads */
 176         if (!ec_dev->cmd_readmem)
 177                 return -ENOTTY;
 178
 179         if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
 180                 return -EFAULT;
 181
 182         num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
 183                                   s_mem.buffer);
 184         if (num <= 0)
 185                 return num;
 186
 187         if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
 188                 return -EFAULT;
 189
 190         return 0;
 191 }
 192
 193 static long ec_device_ioctl(struct file *filp, unsigned int cmd,
 194                             unsigned long arg)
 195 {
 196         struct cros_ec_dev *ec = filp->private_data;
 197
 198         if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
 199                 return -ENOTTY;
 200
 201         switch (cmd) {
 202         case CROS_EC_DEV_IOCXCMD:
 203                 return ec_device_ioctl_xcmd(ec, (void __user *)arg);
 204         case CROS_EC_DEV_IOCRDMEM:
 205                 return ec_device_ioctl_readmem(ec, (void __user *)arg);
 206         }
 207
 208         return -ENOTTY;
 209 }
 210
 211 /* Module initialization */
 212 static const struct file_operations fops = {
 213         .open = ec_device_open,
 214         .release = ec_device_release,
 215         .read = ec_device_read,
 216         .unlocked_ioctl = ec_device_ioctl,
 217 };
 218
 219 static void __remove(struct device *dev)
 220 {
 221         struct cros_ec_dev *ec = container_of(dev, struct cros_ec_dev,
 222                                               class_dev);
 223         kfree(ec);
 224 }
 225
 226 static int ec_device_probe(struct platform_device *pdev)
 227 {
 228         int retval = -ENOMEM;
 229         struct device *dev = &pdev->dev;
 230         struct cros_ec_platform *ec_platform = dev_get_platdata(dev);
 231         dev_t devno = MKDEV(ec_major, pdev->id);
 232         struct cros_ec_dev *ec = kzalloc(sizeof(*ec), GFP_KERNEL);
 233
 234         if (!ec)
 235                 return retval;
 236
 237         dev_set_drvdata(dev, ec);
 238         ec->ec_dev = dev_get_drvdata(dev->parent);
 239         ec->dev = dev;
 240         ec->cmd_offset = ec_platform->cmd_offset;
 241         device_initialize(&ec->class_dev);
 242         cdev_init(&ec->cdev, &fops);
 243
 244         /*
 245          * Add the character device
 246          * Link cdev to the class device to be sure device is not used
 247          * before unbinding it.
 248          */
 249         ec->cdev.kobj.parent = &ec->class_dev.kobj;
 250         retval = cdev_add(&ec->cdev, devno, 1);
 251         if (retval) {
 252                 dev_err(dev, ": failed to add character device\n");
 253                 goto cdev_add_failed;
 254         }
 255
 256         /*
 257          * Add the class device
 258          * Link to the character device for creating the /dev entry
 259          * in devtmpfs.
 260          */
 261         ec->class_dev.devt = ec->cdev.dev;
 262         ec->class_dev.class = &cros_class;
 263         ec->class_dev.parent = dev;
 264         ec->class_dev.release = __remove;
 265
 266         retval = dev_set_name(&ec->class_dev, "%s", ec_platform->ec_name);
 267         if (retval) {
 268                 dev_err(dev, "dev_set_name failed => %d\n", retval);
 269                 goto set_named_failed;
 270         }
 271
 272         retval = device_add(&ec->class_dev);
 273         if (retval) {
 274                 dev_err(dev, "device_register failed => %d\n", retval);
 275                 goto dev_reg_failed;
 276         }
 277
 278         return 0;
 279
 280 dev_reg_failed:
 281 set_named_failed:
 282         dev_set_drvdata(dev, NULL);
 283         cdev_del(&ec->cdev);
 284 cdev_add_failed:
 285         kfree(ec);
 286         return retval;
 287 }
 288
 289 static int ec_device_remove(struct platform_device *pdev)
 290 {
 291         struct cros_ec_dev *ec = dev_get_drvdata(&pdev->dev);
 292         cdev_del(&ec->cdev);
 293         device_unregister(&ec->class_dev);
 294         return 0;
 295 }
 296
 297 static const struct platform_device_id cros_ec_id[] = {
 298         { "cros-ec-ctl", 0 },
 299         { /* sentinel */ },
 300 };
 301 MODULE_DEVICE_TABLE(platform, cros_ec_id);
 302
 303 static struct platform_driver cros_ec_dev_driver = {
 304         .driver = {
 305                 .name = "cros-ec-ctl",
 306         },
 307         .probe = ec_device_probe,
 308         .remove = ec_device_remove,
 309 };
 310
 311 static int __init cros_ec_dev_init(void)
 312 {
 313         int ret;
 314         dev_t dev = 0;
 315
 316         ret  = class_register(&cros_class);
 317         if (ret) {
 318                 pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
 319                 return ret;
 320         }
 321
 322         /* Get a range of minor numbers (starting with 0) to work with */
 323         ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
 324         if (ret < 0) {
 325                 pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
 326                 goto failed_chrdevreg;
 327         }
 328         ec_major = MAJOR(dev);
 329
 330         /* Register the driver */
 331         ret = platform_driver_register(&cros_ec_dev_driver);
 332         if (ret < 0) {
 333                 pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
 334                 goto failed_devreg;
 335         }
 336         return 0;
 337
 338 failed_devreg:
 339         unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
 340 failed_chrdevreg:
 341         class_unregister(&cros_class);
 342         return ret;
 343 }
 344
 345 static void __exit cros_ec_dev_exit(void)
 346 {
 347         platform_driver_unregister(&cros_ec_dev_driver);
 348         unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
 349         class_unregister(&cros_class);
 350 }
 351
 352 module_init(cros_ec_dev_init);
 353 module_exit(cros_ec_dev_exit);
 354
 355 MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
 356 MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
 357 MODULE_VERSION("1.0");
 358 MODULE_LICENSE("GPL");