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