427 lines · c
1// SPDX-License-Identifier: GPL-2.02/*3 * Miscellaneous character driver for ChromeOS Embedded Controller4 *5 * Copyright 2014 Google, Inc.6 * Copyright 2019 Google LLC7 *8 * This file is a rework and part of the code is ported from9 * drivers/mfd/cros_ec_dev.c that was originally written by10 * 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/mod_devicetable.h>18#include <linux/module.h>19#include <linux/notifier.h>20#include <linux/platform_data/cros_ec_chardev.h>21#include <linux/platform_data/cros_ec_commands.h>22#include <linux/platform_data/cros_ec_proto.h>23#include <linux/platform_device.h>24#include <linux/poll.h>25#include <linux/slab.h>26#include <linux/types.h>27#include <linux/uaccess.h>28 29#define DRV_NAME "cros-ec-chardev"30 31/* Arbitrary bounded size for the event queue */32#define CROS_MAX_EVENT_LEN PAGE_SIZE33 34struct chardev_data {35 struct cros_ec_dev *ec_dev;36 struct miscdevice misc;37};38 39struct chardev_priv {40 struct cros_ec_dev *ec_dev;41 struct notifier_block notifier;42 wait_queue_head_t wait_event;43 unsigned long event_mask;44 struct list_head events;45 size_t event_len;46};47 48struct ec_event {49 struct list_head node;50 size_t size;51 u8 event_type;52 u8 data[];53};54 55static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)56{57 static const char * const current_image_name[] = {58 "unknown", "read-only", "read-write", "invalid",59 };60 struct ec_response_get_version *resp;61 struct cros_ec_command *msg;62 int ret;63 64 msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);65 if (!msg)66 return -ENOMEM;67 68 msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;69 msg->insize = sizeof(*resp);70 71 ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);72 if (ret < 0) {73 snprintf(str, maxlen,74 "Unknown EC version, returned error: %d\n",75 msg->result);76 goto exit;77 }78 79 resp = (struct ec_response_get_version *)msg->data;80 if (resp->current_image >= ARRAY_SIZE(current_image_name))81 resp->current_image = 3; /* invalid */82 83 snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,84 resp->version_string_ro, resp->version_string_rw,85 current_image_name[resp->current_image]);86 87 ret = 0;88exit:89 kfree(msg);90 return ret;91}92 93static int cros_ec_chardev_mkbp_event(struct notifier_block *nb,94 unsigned long queued_during_suspend,95 void *_notify)96{97 struct chardev_priv *priv = container_of(nb, struct chardev_priv,98 notifier);99 struct cros_ec_device *ec_dev = priv->ec_dev->ec_dev;100 struct ec_event *event;101 unsigned long event_bit = 1 << ec_dev->event_data.event_type;102 int total_size = sizeof(*event) + ec_dev->event_size;103 104 if (!(event_bit & priv->event_mask) ||105 (priv->event_len + total_size) > CROS_MAX_EVENT_LEN)106 return NOTIFY_DONE;107 108 event = kzalloc(total_size, GFP_KERNEL);109 if (!event)110 return NOTIFY_DONE;111 112 event->size = ec_dev->event_size;113 event->event_type = ec_dev->event_data.event_type;114 memcpy(event->data, &ec_dev->event_data.data, ec_dev->event_size);115 116 spin_lock(&priv->wait_event.lock);117 list_add_tail(&event->node, &priv->events);118 priv->event_len += total_size;119 wake_up_locked(&priv->wait_event);120 spin_unlock(&priv->wait_event.lock);121 122 return NOTIFY_OK;123}124 125static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv,126 bool fetch, bool block)127{128 struct ec_event *event;129 int err;130 131 spin_lock(&priv->wait_event.lock);132 if (!block && list_empty(&priv->events)) {133 event = ERR_PTR(-EWOULDBLOCK);134 goto out;135 }136 137 if (!fetch) {138 event = NULL;139 goto out;140 }141 142 err = wait_event_interruptible_locked(priv->wait_event,143 !list_empty(&priv->events));144 if (err) {145 event = ERR_PTR(err);146 goto out;147 }148 149 event = list_first_entry(&priv->events, struct ec_event, node);150 list_del(&event->node);151 priv->event_len -= sizeof(*event) + event->size;152 153out:154 spin_unlock(&priv->wait_event.lock);155 return event;156}157 158/*159 * Device file ops160 */161static int cros_ec_chardev_open(struct inode *inode, struct file *filp)162{163 struct miscdevice *mdev = filp->private_data;164 struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent);165 struct chardev_priv *priv;166 int ret;167 168 priv = kzalloc(sizeof(*priv), GFP_KERNEL);169 if (!priv)170 return -ENOMEM;171 172 priv->ec_dev = ec_dev;173 filp->private_data = priv;174 INIT_LIST_HEAD(&priv->events);175 init_waitqueue_head(&priv->wait_event);176 nonseekable_open(inode, filp);177 178 priv->notifier.notifier_call = cros_ec_chardev_mkbp_event;179 ret = blocking_notifier_chain_register(&ec_dev->ec_dev->event_notifier,180 &priv->notifier);181 if (ret) {182 dev_err(ec_dev->dev, "failed to register event notifier\n");183 kfree(priv);184 }185 186 return ret;187}188 189static __poll_t cros_ec_chardev_poll(struct file *filp, poll_table *wait)190{191 struct chardev_priv *priv = filp->private_data;192 193 poll_wait(filp, &priv->wait_event, wait);194 195 if (list_empty(&priv->events))196 return 0;197 198 return EPOLLIN | EPOLLRDNORM;199}200 201static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,202 size_t length, loff_t *offset)203{204 char msg[sizeof(struct ec_response_get_version) +205 sizeof(CROS_EC_DEV_VERSION)];206 struct chardev_priv *priv = filp->private_data;207 struct cros_ec_dev *ec_dev = priv->ec_dev;208 size_t count;209 int ret;210 211 if (priv->event_mask) { /* queued MKBP event */212 struct ec_event *event;213 214 event = cros_ec_chardev_fetch_event(priv, length != 0,215 !(filp->f_flags & O_NONBLOCK));216 if (IS_ERR(event))217 return PTR_ERR(event);218 /*219 * length == 0 is special - no IO is done but we check220 * for error conditions.221 */222 if (length == 0)223 return 0;224 225 /* The event is 1 byte of type plus the payload */226 count = min(length, event->size + 1);227 ret = copy_to_user(buffer, &event->event_type, count);228 kfree(event);229 if (ret) /* the copy failed */230 return -EFAULT;231 *offset = count;232 return count;233 }234 235 /*236 * Legacy behavior if no event mask is defined237 */238 if (*offset != 0)239 return 0;240 241 ret = ec_get_version(ec_dev, msg, sizeof(msg));242 if (ret)243 return ret;244 245 count = min(length, strlen(msg));246 247 if (copy_to_user(buffer, msg, count))248 return -EFAULT;249 250 *offset = count;251 return count;252}253 254static int cros_ec_chardev_release(struct inode *inode, struct file *filp)255{256 struct chardev_priv *priv = filp->private_data;257 struct cros_ec_dev *ec_dev = priv->ec_dev;258 struct ec_event *event, *e;259 260 blocking_notifier_chain_unregister(&ec_dev->ec_dev->event_notifier,261 &priv->notifier);262 263 list_for_each_entry_safe(event, e, &priv->events, node) {264 list_del(&event->node);265 kfree(event);266 }267 kfree(priv);268 269 return 0;270}271 272/*273 * Ioctls274 */275static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)276{277 struct cros_ec_command *s_cmd;278 struct cros_ec_command u_cmd;279 long ret;280 281 if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))282 return -EFAULT;283 284 if (u_cmd.outsize > EC_MAX_MSG_BYTES ||285 u_cmd.insize > EC_MAX_MSG_BYTES)286 return -EINVAL;287 288 s_cmd = kzalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),289 GFP_KERNEL);290 if (!s_cmd)291 return -ENOMEM;292 293 if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {294 ret = -EFAULT;295 goto exit;296 }297 298 if (u_cmd.outsize != s_cmd->outsize ||299 u_cmd.insize != s_cmd->insize) {300 ret = -EINVAL;301 goto exit;302 }303 304 s_cmd->command += ec->cmd_offset;305 ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);306 /* Only copy data to userland if data was received. */307 if (ret < 0)308 goto exit;309 310 if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))311 ret = -EFAULT;312exit:313 kfree(s_cmd);314 return ret;315}316 317static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec,318 void __user *arg)319{320 struct cros_ec_device *ec_dev = ec->ec_dev;321 struct cros_ec_readmem s_mem = { };322 long num;323 324 /* Not every platform supports direct reads */325 if (!ec_dev->cmd_readmem)326 return -ENOTTY;327 328 if (copy_from_user(&s_mem, arg, sizeof(s_mem)))329 return -EFAULT;330 331 if (s_mem.bytes > sizeof(s_mem.buffer))332 return -EINVAL;333 334 num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,335 s_mem.buffer);336 if (num <= 0)337 return num;338 339 if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))340 return -EFAULT;341 342 return num;343}344 345static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,346 unsigned long arg)347{348 struct chardev_priv *priv = filp->private_data;349 struct cros_ec_dev *ec = priv->ec_dev;350 351 if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)352 return -ENOTTY;353 354 switch (cmd) {355 case CROS_EC_DEV_IOCXCMD:356 return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);357 case CROS_EC_DEV_IOCRDMEM:358 return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);359 case CROS_EC_DEV_IOCEVENTMASK:360 priv->event_mask = arg;361 return 0;362 }363 364 return -ENOTTY;365}366 367static const struct file_operations chardev_fops = {368 .open = cros_ec_chardev_open,369 .poll = cros_ec_chardev_poll,370 .read = cros_ec_chardev_read,371 .release = cros_ec_chardev_release,372 .unlocked_ioctl = cros_ec_chardev_ioctl,373#ifdef CONFIG_COMPAT374 .compat_ioctl = cros_ec_chardev_ioctl,375#endif376};377 378static int cros_ec_chardev_probe(struct platform_device *pdev)379{380 struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);381 struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);382 struct chardev_data *data;383 384 /* Create a char device: we want to create it anew */385 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);386 if (!data)387 return -ENOMEM;388 389 data->ec_dev = ec_dev;390 data->misc.minor = MISC_DYNAMIC_MINOR;391 data->misc.fops = &chardev_fops;392 data->misc.name = ec_platform->ec_name;393 data->misc.parent = pdev->dev.parent;394 395 dev_set_drvdata(&pdev->dev, data);396 397 return misc_register(&data->misc);398}399 400static void cros_ec_chardev_remove(struct platform_device *pdev)401{402 struct chardev_data *data = dev_get_drvdata(&pdev->dev);403 404 misc_deregister(&data->misc);405}406 407static const struct platform_device_id cros_ec_chardev_id[] = {408 { DRV_NAME, 0 },409 {}410};411MODULE_DEVICE_TABLE(platform, cros_ec_chardev_id);412 413static struct platform_driver cros_ec_chardev_driver = {414 .driver = {415 .name = DRV_NAME,416 },417 .probe = cros_ec_chardev_probe,418 .remove_new = cros_ec_chardev_remove,419 .id_table = cros_ec_chardev_id,420};421 422module_platform_driver(cros_ec_chardev_driver);423 424MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");425MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver");426MODULE_LICENSE("GPL");427