// SPDX-License-Identifier: GPL-2.0
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/*
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* Greybus driver for the Raw protocol
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*
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* Copyright 2015 Google Inc.
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* Copyright 2015 Linaro Ltd.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/sizes.h>
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#include <linux/cdev.h>
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#include <linux/fs.h>
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#include <linux/idr.h>
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#include <linux/uaccess.h>
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#include <linux/greybus.h>
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struct gb_raw {
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struct gb_connection *connection;
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struct list_head list;
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int list_data;
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struct mutex list_lock;
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dev_t dev;
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struct cdev cdev;
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struct device *device;
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};
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struct raw_data {
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struct list_head entry;
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u32 len;
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u8 data[];
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};
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static struct class *raw_class;
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static int raw_major;
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static const struct file_operations raw_fops;
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static DEFINE_IDA(minors);
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/* Number of minor devices this driver supports */
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#define NUM_MINORS 256
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/* Maximum size of any one send data buffer we support */
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#define MAX_PACKET_SIZE (PAGE_SIZE * 2)
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/*
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* Maximum size of the data in the receive buffer we allow before we start to
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* drop messages on the floor
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*/
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#define MAX_DATA_SIZE (MAX_PACKET_SIZE * 8)
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/*
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* Add the raw data message to the list of received messages.
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*/
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static int receive_data(struct gb_raw *raw, u32 len, u8 *data)
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{
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struct raw_data *raw_data;
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struct device *dev = &raw->connection->bundle->dev;
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int retval = 0;
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if (len > MAX_PACKET_SIZE) {
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dev_err(dev, "Too big of a data packet, rejected\n");
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return -EINVAL;
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}
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mutex_lock(&raw->list_lock);
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if ((raw->list_data + len) > MAX_DATA_SIZE) {
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dev_err(dev, "Too much data in receive buffer, now dropping packets\n");
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retval = -EINVAL;
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goto exit;
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}
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raw_data = kmalloc(sizeof(*raw_data) + len, GFP_KERNEL);
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if (!raw_data) {
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retval = -ENOMEM;
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goto exit;
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}
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raw->list_data += len;
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raw_data->len = len;
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memcpy(&raw_data->data[0], data, len);
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list_add_tail(&raw_data->entry, &raw->list);
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exit:
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mutex_unlock(&raw->list_lock);
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return retval;
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}
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static int gb_raw_request_handler(struct gb_operation *op)
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{
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struct gb_connection *connection = op->connection;
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struct device *dev = &connection->bundle->dev;
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struct gb_raw *raw = greybus_get_drvdata(connection->bundle);
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struct gb_raw_send_request *receive;
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u32 len;
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if (op->type != GB_RAW_TYPE_SEND) {
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dev_err(dev, "unknown request type 0x%02x\n", op->type);
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return -EINVAL;
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}
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/* Verify size of payload */
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if (op->request->payload_size < sizeof(*receive)) {
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dev_err(dev, "raw receive request too small (%zu < %zu)\n",
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op->request->payload_size, sizeof(*receive));
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return -EINVAL;
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}
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receive = op->request->payload;
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len = le32_to_cpu(receive->len);
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if (len != (int)(op->request->payload_size - sizeof(__le32))) {
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dev_err(dev, "raw receive request wrong size %d vs %d\n", len,
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(int)(op->request->payload_size - sizeof(__le32)));
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return -EINVAL;
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}
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if (len == 0) {
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dev_err(dev, "raw receive request of 0 bytes?\n");
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return -EINVAL;
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}
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return receive_data(raw, len, receive->data);
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}
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static int gb_raw_send(struct gb_raw *raw, u32 len, const char __user *data)
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{
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struct gb_connection *connection = raw->connection;
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struct gb_raw_send_request *request;
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int retval;
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request = kmalloc(len + sizeof(*request), GFP_KERNEL);
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if (!request)
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return -ENOMEM;
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if (copy_from_user(&request->data[0], data, len)) {
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kfree(request);
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return -EFAULT;
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}
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request->len = cpu_to_le32(len);
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retval = gb_operation_sync(connection, GB_RAW_TYPE_SEND,
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request, len + sizeof(*request),
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NULL, 0);
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kfree(request);
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return retval;
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}
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static int gb_raw_probe(struct gb_bundle *bundle,
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const struct greybus_bundle_id *id)
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{
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struct greybus_descriptor_cport *cport_desc;
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struct gb_connection *connection;
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struct gb_raw *raw;
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int retval;
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int minor;
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if (bundle->num_cports != 1)
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return -ENODEV;
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cport_desc = &bundle->cport_desc[0];
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if (cport_desc->protocol_id != GREYBUS_PROTOCOL_RAW)
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return -ENODEV;
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raw = kzalloc(sizeof(*raw), GFP_KERNEL);
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if (!raw)
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return -ENOMEM;
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connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
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gb_raw_request_handler);
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if (IS_ERR(connection)) {
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retval = PTR_ERR(connection);
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goto error_free;
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}
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INIT_LIST_HEAD(&raw->list);
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mutex_init(&raw->list_lock);
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raw->connection = connection;
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greybus_set_drvdata(bundle, raw);
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minor = ida_simple_get(&minors, 0, 0, GFP_KERNEL);
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if (minor < 0) {
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retval = minor;
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goto error_connection_destroy;
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}
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raw->dev = MKDEV(raw_major, minor);
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cdev_init(&raw->cdev, &raw_fops);
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retval = gb_connection_enable(connection);
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if (retval)
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goto error_remove_ida;
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retval = cdev_add(&raw->cdev, raw->dev, 1);
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if (retval)
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goto error_connection_disable;
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raw->device = device_create(raw_class, &connection->bundle->dev,
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raw->dev, raw, "gb!raw%d", minor);
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if (IS_ERR(raw->device)) {
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retval = PTR_ERR(raw->device);
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goto error_del_cdev;
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}
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return 0;
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error_del_cdev:
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cdev_del(&raw->cdev);
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error_connection_disable:
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gb_connection_disable(connection);
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error_remove_ida:
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ida_simple_remove(&minors, minor);
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error_connection_destroy:
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gb_connection_destroy(connection);
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error_free:
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kfree(raw);
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return retval;
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}
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static void gb_raw_disconnect(struct gb_bundle *bundle)
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{
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struct gb_raw *raw = greybus_get_drvdata(bundle);
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struct gb_connection *connection = raw->connection;
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struct raw_data *raw_data;
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struct raw_data *temp;
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// FIXME - handle removing a connection when the char device node is open.
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device_destroy(raw_class, raw->dev);
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cdev_del(&raw->cdev);
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gb_connection_disable(connection);
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ida_simple_remove(&minors, MINOR(raw->dev));
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gb_connection_destroy(connection);
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mutex_lock(&raw->list_lock);
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list_for_each_entry_safe(raw_data, temp, &raw->list, entry) {
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list_del(&raw_data->entry);
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kfree(raw_data);
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}
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mutex_unlock(&raw->list_lock);
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kfree(raw);
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}
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/*
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* Character device node interfaces.
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*
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* Note, we are using read/write to only allow a single read/write per message.
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* This means for read(), you have to provide a big enough buffer for the full
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* message to be copied into. If the buffer isn't big enough, the read() will
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* fail with -ENOSPC.
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*/
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static int raw_open(struct inode *inode, struct file *file)
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{
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struct cdev *cdev = inode->i_cdev;
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struct gb_raw *raw = container_of(cdev, struct gb_raw, cdev);
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file->private_data = raw;
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return 0;
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}
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static ssize_t raw_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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struct gb_raw *raw = file->private_data;
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int retval;
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if (!count)
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return 0;
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if (count > MAX_PACKET_SIZE)
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return -E2BIG;
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retval = gb_raw_send(raw, count, buf);
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if (retval)
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return retval;
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return count;
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}
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static ssize_t raw_read(struct file *file, char __user *buf, size_t count,
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loff_t *ppos)
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{
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struct gb_raw *raw = file->private_data;
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int retval = 0;
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struct raw_data *raw_data;
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mutex_lock(&raw->list_lock);
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if (list_empty(&raw->list))
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goto exit;
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raw_data = list_first_entry(&raw->list, struct raw_data, entry);
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if (raw_data->len > count) {
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retval = -ENOSPC;
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goto exit;
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}
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if (copy_to_user(buf, &raw_data->data[0], raw_data->len)) {
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retval = -EFAULT;
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goto exit;
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}
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list_del(&raw_data->entry);
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raw->list_data -= raw_data->len;
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retval = raw_data->len;
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kfree(raw_data);
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exit:
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mutex_unlock(&raw->list_lock);
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return retval;
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}
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static const struct file_operations raw_fops = {
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.owner = THIS_MODULE,
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.write = raw_write,
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.read = raw_read,
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.open = raw_open,
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.llseek = noop_llseek,
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};
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static const struct greybus_bundle_id gb_raw_id_table[] = {
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{ GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_RAW) },
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{ }
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};
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MODULE_DEVICE_TABLE(greybus, gb_raw_id_table);
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static struct greybus_driver gb_raw_driver = {
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.name = "raw",
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.probe = gb_raw_probe,
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.disconnect = gb_raw_disconnect,
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.id_table = gb_raw_id_table,
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};
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static int raw_init(void)
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{
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dev_t dev;
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int retval;
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raw_class = class_create(THIS_MODULE, "gb_raw");
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if (IS_ERR(raw_class)) {
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retval = PTR_ERR(raw_class);
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goto error_class;
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}
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retval = alloc_chrdev_region(&dev, 0, NUM_MINORS, "gb_raw");
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if (retval < 0)
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goto error_chrdev;
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raw_major = MAJOR(dev);
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retval = greybus_register(&gb_raw_driver);
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if (retval)
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goto error_gb;
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return 0;
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error_gb:
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unregister_chrdev_region(dev, NUM_MINORS);
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error_chrdev:
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class_destroy(raw_class);
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error_class:
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return retval;
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}
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module_init(raw_init);
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static void __exit raw_exit(void)
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{
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greybus_deregister(&gb_raw_driver);
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unregister_chrdev_region(MKDEV(raw_major, 0), NUM_MINORS);
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class_destroy(raw_class);
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ida_destroy(&minors);
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}
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module_exit(raw_exit);
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MODULE_LICENSE("GPL v2");
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