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/uaccess.h>
  24
  25 #include "cros_ec_dev.h"
  26
  27 /* Device variables */
  28 #define CROS_MAX_DEV 128
  29 static struct class *cros_class;
  30 static int ec_major;
  31
  32 /* Basic communication */
  33 static int ec_get_version(struct cros_ec_device *ec, char *str, int maxlen)
  34 {
  35         struct ec_response_get_version *resp;
  36         static const char * const current_image_name[] = {
  37                 "unknown", "read-only", "read-write", "invalid",
  38         };
  39         struct cros_ec_command msg = {
  40                 .version = 0,
  41                 .command = EC_CMD_GET_VERSION,
  42                 .outdata = { 0 },
  43                 .outsize = 0,
  44                 .indata = { 0 },
  45                 .insize = sizeof(*resp),
  46         };
  47         int ret;
  48
  49         ret = cros_ec_cmd_xfer(ec, &msg);
  50         if (ret < 0)
  51                 return ret;
  52
  53         if (msg.result != EC_RES_SUCCESS) {
  54                 snprintf(str, maxlen,
  55                          "%s\nUnknown EC version: EC returned %d\n",
  56                          CROS_EC_DEV_VERSION, msg.result);
  57                 return 0;
  58         }
  59
  60         resp = (struct ec_response_get_version *)msg.indata;
  61         if (resp->current_image >= ARRAY_SIZE(current_image_name))
  62                 resp->current_image = 3; /* invalid */
  63
  64         snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
  65                  resp->version_string_ro, resp->version_string_rw,
  66                  current_image_name[resp->current_image]);
  67
  68         return 0;
  69 }
  70
  71 /* Device file ops */
  72 static int ec_device_open(struct inode *inode, struct file *filp)
  73 {
  74         filp->private_data = container_of(inode->i_cdev,
  75                                           struct cros_ec_device, cdev);
  76         return 0;
  77 }
  78
  79 static int ec_device_release(struct inode *inode, struct file *filp)
  80 {
  81         return 0;
  82 }
  83
  84 static ssize_t ec_device_read(struct file *filp, char __user *buffer,
  85                               size_t length, loff_t *offset)
  86 {
  87         struct cros_ec_device *ec = filp->private_data;
  88         char msg[sizeof(struct ec_response_get_version) +
  89                  sizeof(CROS_EC_DEV_VERSION)];
  90         size_t count;
  91         int ret;
  92
  93         if (*offset != 0)
  94                 return 0;
  95
  96         ret = ec_get_version(ec, msg, sizeof(msg));
  97         if (ret)
  98                 return ret;
  99
 100         count = min(length, strlen(msg));
 101
 102         if (copy_to_user(buffer, msg, count))
 103                 return -EFAULT;
 104
 105         *offset = count;
 106         return count;
 107 }
 108
 109 /* Ioctls */
 110 static long ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg)
 111 {
 112         long ret;
 113         struct cros_ec_command s_cmd = { };
 114
 115         if (copy_from_user(&s_cmd, arg, sizeof(s_cmd)))
 116                 return -EFAULT;
 117
 118         ret = cros_ec_cmd_xfer(ec, &s_cmd);
 119         /* Only copy data to userland if data was received. */
 120         if (ret < 0)
 121                 return ret;
 122
 123         if (copy_to_user(arg, &s_cmd, sizeof(s_cmd)))
 124                 return -EFAULT;
 125
 126         return 0;
 127 }
 128
 129 static long ec_device_ioctl_readmem(struct cros_ec_device *ec, void __user *arg)
 130 {
 131         struct cros_ec_readmem s_mem = { };
 132         long num;
 133
 134         /* Not every platform supports direct reads */
 135         if (!ec->cmd_readmem)
 136                 return -ENOTTY;
 137
 138         if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
 139                 return -EFAULT;
 140
 141         num = ec->cmd_readmem(ec, s_mem.offset, s_mem.bytes, s_mem.buffer);
 142         if (num <= 0)
 143                 return num;
 144
 145         if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
 146                 return -EFAULT;
 147
 148         return 0;
 149 }
 150
 151 static long ec_device_ioctl(struct file *filp, unsigned int cmd,
 152                             unsigned long arg)
 153 {
 154         struct cros_ec_device *ec = filp->private_data;
 155
 156         if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
 157                 return -ENOTTY;
 158
 159         switch (cmd) {
 160         case CROS_EC_DEV_IOCXCMD:
 161                 return ec_device_ioctl_xcmd(ec, (void __user *)arg);
 162         case CROS_EC_DEV_IOCRDMEM:
 163                 return ec_device_ioctl_readmem(ec, (void __user *)arg);
 164         }
 165
 166         return -ENOTTY;
 167 }
 168
 169 /* Module initialization */
 170 static const struct file_operations fops = {
 171         .open = ec_device_open,
 172         .release = ec_device_release,
 173         .read = ec_device_read,
 174         .unlocked_ioctl = ec_device_ioctl,
 175 };
 176
 177 static int ec_device_probe(struct platform_device *pdev)
 178 {
 179         struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
 180         int retval = -ENOTTY;
 181         dev_t devno = MKDEV(ec_major, 0);
 182
 183         /* Instantiate it (and remember the EC) */
 184         cdev_init(&ec->cdev, &fops);
 185
 186         retval = cdev_add(&ec->cdev, devno, 1);
 187         if (retval) {
 188                 dev_err(&pdev->dev, ": failed to add character device\n");
 189                 return retval;
 190         }
 191
 192         ec->vdev = device_create(cros_class, NULL, devno, ec,
 193                                  CROS_EC_DEV_NAME);
 194         if (IS_ERR(ec->vdev)) {
 195                 retval = PTR_ERR(ec->vdev);
 196                 dev_err(&pdev->dev, ": failed to create device\n");
 197                 cdev_del(&ec->cdev);
 198                 return retval;
 199         }
 200
 201         /* Initialize extra interfaces */
 202         ec_dev_sysfs_init(ec);
 203         ec_dev_lightbar_init(ec);
 204
 205         return 0;
 206 }
 207
 208 static int ec_device_remove(struct platform_device *pdev)
 209 {
 210         struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
 211
 212         ec_dev_lightbar_remove(ec);
 213         ec_dev_sysfs_remove(ec);
 214         device_destroy(cros_class, MKDEV(ec_major, 0));
 215         cdev_del(&ec->cdev);
 216         return 0;
 217 }
 218
 219 static struct platform_driver cros_ec_dev_driver = {
 220         .driver = {
 221                 .name = "cros-ec-ctl",
 222         },
 223         .probe = ec_device_probe,
 224         .remove = ec_device_remove,
 225 };
 226
 227 static int __init cros_ec_dev_init(void)
 228 {
 229         int ret;
 230         dev_t dev = 0;
 231
 232         cros_class = class_create(THIS_MODULE, "chromeos");
 233         if (IS_ERR(cros_class)) {
 234                 pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
 235                 return PTR_ERR(cros_class);
 236         }
 237
 238         /* Get a range of minor numbers (starting with 0) to work with */
 239         ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
 240         if (ret < 0) {
 241                 pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
 242                 goto failed_chrdevreg;
 243         }
 244         ec_major = MAJOR(dev);
 245
 246         /* Register the driver */
 247         ret = platform_driver_register(&cros_ec_dev_driver);
 248         if (ret < 0) {
 249                 pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
 250                 goto failed_devreg;
 251         }
 252         return 0;
 253
 254 failed_devreg:
 255         unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
 256 failed_chrdevreg:
 257         class_destroy(cros_class);
 258         return ret;
 259 }
 260
 261 static void __exit cros_ec_dev_exit(void)
 262 {
 263         platform_driver_unregister(&cros_ec_dev_driver);
 264         unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
 265         class_destroy(cros_class);
 266 }
 267
 268 module_init(cros_ec_dev_init);
 269 module_exit(cros_ec_dev_exit);
 270
 271 MODULE_AUTHOR("Bill Richardson <wfrichar@chromium.org>");
 272 MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
 273 MODULE_VERSION("1.0");
 274 MODULE_LICENSE("GPL");