LXR linux/drivers/staging/greybus/log.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Greybus driver for the log protocol
   4 *
   5 * Copyright 2016 Google Inc.
   6 */
   7#include <linux/kernel.h>
   8#include <linux/module.h>
   9#include <linux/slab.h>
  10#include <linux/sizes.h>
  11#include <linux/uaccess.h>
  12#include <linux/greybus.h>
  13
  14struct gb_log {
  15        struct gb_connection *connection;
  16};
  17
  18static int gb_log_request_handler(struct gb_operation *op)
  19{
  20        struct gb_connection *connection = op->connection;
  21        struct device *dev = &connection->bundle->dev;
  22        struct gb_log_send_log_request *receive;
  23        u16 len;
  24
  25        if (op->type != GB_LOG_TYPE_SEND_LOG) {
  26                dev_err(dev, "unknown request type 0x%02x\n", op->type);
  27                return -EINVAL;
  28        }
  29
  30        /* Verify size of payload */
  31        if (op->request->payload_size < sizeof(*receive)) {
  32                dev_err(dev, "log request too small (%zu < %zu)\n",
  33                        op->request->payload_size, sizeof(*receive));
  34                return -EINVAL;
  35        }
  36        receive = op->request->payload;
  37        len = le16_to_cpu(receive->len);
  38        if (len != (op->request->payload_size - sizeof(*receive))) {
  39                dev_err(dev, "log request wrong size %d vs %zu\n", len,
  40                        (op->request->payload_size - sizeof(*receive)));
  41                return -EINVAL;
  42        }
  43        if (len == 0) {
  44                dev_err(dev, "log request of 0 bytes?\n");
  45                return -EINVAL;
  46        }
  47
  48        if (len > GB_LOG_MAX_LEN) {
  49                dev_err(dev, "log request too big: %d\n", len);
  50                return -EINVAL;
  51        }
  52
  53        /* Ensure the buffer is 0 terminated */
  54        receive->msg[len - 1] = '\0';
  55
  56        /*
  57         * Print with dev_dbg() so that it can be easily turned off using
  58         * dynamic debugging (and prevent any DoS)
  59         */
  60        dev_dbg(dev, "%s", receive->msg);
  61
  62        return 0;
  63}
  64
  65static int gb_log_probe(struct gb_bundle *bundle,
  66                        const struct greybus_bundle_id *id)
  67{
  68        struct greybus_descriptor_cport *cport_desc;
  69        struct gb_connection *connection;
  70        struct gb_log *log;
  71        int retval;
  72
  73        if (bundle->num_cports != 1)
  74                return -ENODEV;
  75
  76        cport_desc = &bundle->cport_desc[0];
  77        if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
  78                return -ENODEV;
  79
  80        log = kzalloc(sizeof(*log), GFP_KERNEL);
  81        if (!log)
  82                return -ENOMEM;
  83
  84        connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
  85                                          gb_log_request_handler);
  86        if (IS_ERR(connection)) {
  87                retval = PTR_ERR(connection);
  88                goto error_free;
  89        }
  90
  91        log->connection = connection;
  92        greybus_set_drvdata(bundle, log);
  93
  94        retval = gb_connection_enable(connection);
  95        if (retval)
  96                goto error_connection_destroy;
  97
  98        return 0;
  99
 100error_connection_destroy:
 101        gb_connection_destroy(connection);
 102error_free:
 103        kfree(log);
 104        return retval;
 105}
 106
 107static void gb_log_disconnect(struct gb_bundle *bundle)
 108{
 109        struct gb_log *log = greybus_get_drvdata(bundle);
 110        struct gb_connection *connection = log->connection;
 111
 112        gb_connection_disable(connection);
 113        gb_connection_destroy(connection);
 114
 115        kfree(log);
 116}
 117
 118static const struct greybus_bundle_id gb_log_id_table[] = {
 119        { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
 120        { }
 121};
 122MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
 123
 124static struct greybus_driver gb_log_driver = {
 125        .name           = "log",
 126        .probe          = gb_log_probe,
 127        .disconnect     = gb_log_disconnect,
 128        .id_table       = gb_log_id_table,
 129};
 130module_greybus_driver(gb_log_driver);
 131
 132MODULE_LICENSE("GPL v2");
 133