| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Miscellaneous character driver for ChromeOS Embedded Controller |
| * |
| * Copyright 2014 Google, Inc. |
| * Copyright 2019 Google LLC |
| * |
| * This file is a rework and part of the code is ported from |
| * drivers/mfd/cros_ec_dev.c that was originally written by |
| * Bill Richardson. |
| */ |
| |
| #include <linux/init.h> |
| #include <linux/device.h> |
| #include <linux/fs.h> |
| #include <linux/miscdevice.h> |
| #include <linux/module.h> |
| #include <linux/notifier.h> |
| #include <linux/platform_data/cros_ec_chardev.h> |
| #include <linux/platform_data/cros_ec_commands.h> |
| #include <linux/platform_data/cros_ec_proto.h> |
| #include <linux/platform_device.h> |
| #include <linux/poll.h> |
| #include <linux/slab.h> |
| #include <linux/types.h> |
| #include <linux/uaccess.h> |
| |
| #define DRV_NAME "cros-ec-chardev" |
| |
| /* Arbitrary bounded size for the event queue */ |
| #define CROS_MAX_EVENT_LEN PAGE_SIZE |
| |
| struct chardev_data { |
| struct cros_ec_dev *ec_dev; |
| struct miscdevice misc; |
| }; |
| |
| struct chardev_priv { |
| struct cros_ec_dev *ec_dev; |
| struct notifier_block notifier; |
| wait_queue_head_t wait_event; |
| unsigned long event_mask; |
| struct list_head events; |
| size_t event_len; |
| }; |
| |
| struct ec_event { |
| struct list_head node; |
| size_t size; |
| u8 event_type; |
| u8 data[0]; |
| }; |
| |
| static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen) |
| { |
| static const char * const current_image_name[] = { |
| "unknown", "read-only", "read-write", "invalid", |
| }; |
| struct ec_response_get_version *resp; |
| struct cros_ec_command *msg; |
| int ret; |
| |
| msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL); |
| if (!msg) |
| return -ENOMEM; |
| |
| msg->command = EC_CMD_GET_VERSION + ec->cmd_offset; |
| msg->insize = sizeof(*resp); |
| |
| ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg); |
| if (ret < 0) { |
| snprintf(str, maxlen, |
| "Unknown EC version, returned error: %d\n", |
| msg->result); |
| goto exit; |
| } |
| |
| resp = (struct ec_response_get_version *)msg->data; |
| if (resp->current_image >= ARRAY_SIZE(current_image_name)) |
| resp->current_image = 3; /* invalid */ |
| |
| snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION, |
| resp->version_string_ro, resp->version_string_rw, |
| current_image_name[resp->current_image]); |
| |
| ret = 0; |
| exit: |
| kfree(msg); |
| return ret; |
| } |
| |
| static int cros_ec_chardev_mkbp_event(struct notifier_block *nb, |
| unsigned long queued_during_suspend, |
| void *_notify) |
| { |
| struct chardev_priv *priv = container_of(nb, struct chardev_priv, |
| notifier); |
| struct cros_ec_device *ec_dev = priv->ec_dev->ec_dev; |
| struct ec_event *event; |
| unsigned long event_bit = 1 << ec_dev->event_data.event_type; |
| int total_size = sizeof(*event) + ec_dev->event_size; |
| |
| if (!(event_bit & priv->event_mask) || |
| (priv->event_len + total_size) > CROS_MAX_EVENT_LEN) |
| return NOTIFY_DONE; |
| |
| event = kzalloc(total_size, GFP_KERNEL); |
| if (!event) |
| return NOTIFY_DONE; |
| |
| event->size = ec_dev->event_size; |
| event->event_type = ec_dev->event_data.event_type; |
| memcpy(event->data, &ec_dev->event_data.data, ec_dev->event_size); |
| |
| spin_lock(&priv->wait_event.lock); |
| list_add_tail(&event->node, &priv->events); |
| priv->event_len += total_size; |
| wake_up_locked(&priv->wait_event); |
| spin_unlock(&priv->wait_event.lock); |
| |
| return NOTIFY_OK; |
| } |
| |
| static struct ec_event *cros_ec_chardev_fetch_event(struct chardev_priv *priv, |
| bool fetch, bool block) |
| { |
| struct ec_event *event; |
| int err; |
| |
| spin_lock(&priv->wait_event.lock); |
| if (!block && list_empty(&priv->events)) { |
| event = ERR_PTR(-EWOULDBLOCK); |
| goto out; |
| } |
| |
| if (!fetch) { |
| event = NULL; |
| goto out; |
| } |
| |
| err = wait_event_interruptible_locked(priv->wait_event, |
| !list_empty(&priv->events)); |
| if (err) { |
| event = ERR_PTR(err); |
| goto out; |
| } |
| |
| event = list_first_entry(&priv->events, struct ec_event, node); |
| list_del(&event->node); |
| priv->event_len -= sizeof(*event) + event->size; |
| |
| out: |
| spin_unlock(&priv->wait_event.lock); |
| return event; |
| } |
| |
| /* |
| * Device file ops |
| */ |
| static int cros_ec_chardev_open(struct inode *inode, struct file *filp) |
| { |
| struct miscdevice *mdev = filp->private_data; |
| struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent); |
| struct chardev_priv *priv; |
| int ret; |
| |
| priv = kzalloc(sizeof(*priv), GFP_KERNEL); |
| if (!priv) |
| return -ENOMEM; |
| |
| priv->ec_dev = ec_dev; |
| filp->private_data = priv; |
| INIT_LIST_HEAD(&priv->events); |
| init_waitqueue_head(&priv->wait_event); |
| nonseekable_open(inode, filp); |
| |
| priv->notifier.notifier_call = cros_ec_chardev_mkbp_event; |
| ret = blocking_notifier_chain_register(&ec_dev->ec_dev->event_notifier, |
| &priv->notifier); |
| if (ret) { |
| dev_err(ec_dev->dev, "failed to register event notifier\n"); |
| kfree(priv); |
| } |
| |
| return ret; |
| } |
| |
| static __poll_t cros_ec_chardev_poll(struct file *filp, poll_table *wait) |
| { |
| struct chardev_priv *priv = filp->private_data; |
| |
| poll_wait(filp, &priv->wait_event, wait); |
| |
| if (list_empty(&priv->events)) |
| return 0; |
| |
| return EPOLLIN | EPOLLRDNORM; |
| } |
| |
| static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer, |
| size_t length, loff_t *offset) |
| { |
| char msg[sizeof(struct ec_response_get_version) + |
| sizeof(CROS_EC_DEV_VERSION)]; |
| struct chardev_priv *priv = filp->private_data; |
| struct cros_ec_dev *ec_dev = priv->ec_dev; |
| size_t count; |
| int ret; |
| |
| if (priv->event_mask) { /* queued MKBP event */ |
| struct ec_event *event; |
| |
| event = cros_ec_chardev_fetch_event(priv, length != 0, |
| !(filp->f_flags & O_NONBLOCK)); |
| if (IS_ERR(event)) |
| return PTR_ERR(event); |
| /* |
| * length == 0 is special - no IO is done but we check |
| * for error conditions. |
| */ |
| if (length == 0) |
| return 0; |
| |
| /* The event is 1 byte of type plus the payload */ |
| count = min(length, event->size + 1); |
| ret = copy_to_user(buffer, &event->event_type, count); |
| kfree(event); |
| if (ret) /* the copy failed */ |
| return -EFAULT; |
| *offset = count; |
| return count; |
| } |
| |
| /* |
| * Legacy behavior if no event mask is defined |
| */ |
| if (*offset != 0) |
| return 0; |
| |
| ret = ec_get_version(ec_dev, msg, sizeof(msg)); |
| if (ret) |
| return ret; |
| |
| count = min(length, strlen(msg)); |
| |
| if (copy_to_user(buffer, msg, count)) |
| return -EFAULT; |
| |
| *offset = count; |
| return count; |
| } |
| |
| static int cros_ec_chardev_release(struct inode *inode, struct file *filp) |
| { |
| struct chardev_priv *priv = filp->private_data; |
| struct cros_ec_dev *ec_dev = priv->ec_dev; |
| struct ec_event *event, *e; |
| |
| blocking_notifier_chain_unregister(&ec_dev->ec_dev->event_notifier, |
| &priv->notifier); |
| |
| list_for_each_entry_safe(event, e, &priv->events, node) { |
| list_del(&event->node); |
| kfree(event); |
| } |
| kfree(priv); |
| |
| return 0; |
| } |
| |
| /* |
| * Ioctls |
| */ |
| static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg) |
| { |
| struct cros_ec_command *s_cmd; |
| struct cros_ec_command u_cmd; |
| long ret; |
| |
| if (copy_from_user(&u_cmd, arg, sizeof(u_cmd))) |
| return -EFAULT; |
| |
| if (u_cmd.outsize > EC_MAX_MSG_BYTES || |
| u_cmd.insize > EC_MAX_MSG_BYTES) |
| return -EINVAL; |
| |
| s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize), |
| GFP_KERNEL); |
| if (!s_cmd) |
| return -ENOMEM; |
| |
| if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) { |
| ret = -EFAULT; |
| goto exit; |
| } |
| |
| if (u_cmd.outsize != s_cmd->outsize || |
| u_cmd.insize != s_cmd->insize) { |
| ret = -EINVAL; |
| goto exit; |
| } |
| |
| s_cmd->command += ec->cmd_offset; |
| ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd); |
| /* Only copy data to userland if data was received. */ |
| if (ret < 0) |
| goto exit; |
| |
| if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize)) |
| ret = -EFAULT; |
| exit: |
| kfree(s_cmd); |
| return ret; |
| } |
| |
| static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec, |
| void __user *arg) |
| { |
| struct cros_ec_device *ec_dev = ec->ec_dev; |
| struct cros_ec_readmem s_mem = { }; |
| long num; |
| |
| /* Not every platform supports direct reads */ |
| if (!ec_dev->cmd_readmem) |
| return -ENOTTY; |
| |
| if (copy_from_user(&s_mem, arg, sizeof(s_mem))) |
| return -EFAULT; |
| |
| num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes, |
| s_mem.buffer); |
| if (num <= 0) |
| return num; |
| |
| if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem))) |
| return -EFAULT; |
| |
| return num; |
| } |
| |
| static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd, |
| unsigned long arg) |
| { |
| struct chardev_priv *priv = filp->private_data; |
| struct cros_ec_dev *ec = priv->ec_dev; |
| |
| if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC) |
| return -ENOTTY; |
| |
| switch (cmd) { |
| case CROS_EC_DEV_IOCXCMD: |
| return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg); |
| case CROS_EC_DEV_IOCRDMEM: |
| return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg); |
| case CROS_EC_DEV_IOCEVENTMASK: |
| priv->event_mask = arg; |
| return 0; |
| } |
| |
| return -ENOTTY; |
| } |
| |
| static const struct file_operations chardev_fops = { |
| .open = cros_ec_chardev_open, |
| .poll = cros_ec_chardev_poll, |
| .read = cros_ec_chardev_read, |
| .release = cros_ec_chardev_release, |
| .unlocked_ioctl = cros_ec_chardev_ioctl, |
| #ifdef CONFIG_COMPAT |
| .compat_ioctl = cros_ec_chardev_ioctl, |
| #endif |
| }; |
| |
| static int cros_ec_chardev_probe(struct platform_device *pdev) |
| { |
| struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent); |
| struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev); |
| struct chardev_data *data; |
| |
| /* Create a char device: we want to create it anew */ |
| data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); |
| if (!data) |
| return -ENOMEM; |
| |
| data->ec_dev = ec_dev; |
| data->misc.minor = MISC_DYNAMIC_MINOR; |
| data->misc.fops = &chardev_fops; |
| data->misc.name = ec_platform->ec_name; |
| data->misc.parent = pdev->dev.parent; |
| |
| dev_set_drvdata(&pdev->dev, data); |
| |
| return misc_register(&data->misc); |
| } |
| |
| static int cros_ec_chardev_remove(struct platform_device *pdev) |
| { |
| struct chardev_data *data = dev_get_drvdata(&pdev->dev); |
| |
| misc_deregister(&data->misc); |
| |
| return 0; |
| } |
| |
| static struct platform_driver cros_ec_chardev_driver = { |
| .driver = { |
| .name = DRV_NAME, |
| }, |
| .probe = cros_ec_chardev_probe, |
| .remove = cros_ec_chardev_remove, |
| }; |
| |
| module_platform_driver(cros_ec_chardev_driver); |
| |
| MODULE_ALIAS("platform:" DRV_NAME); |
| MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>"); |
| MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver"); |
| MODULE_LICENSE("GPL"); |