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
  13#include "greybus.h"
  14
  15struct gb_log {
  16        struct gb_connection *connection;
  17};
  18
  19static int gb_log_request_handler(struct gb_operation *op)
  20{
  21        struct gb_connection *connection = op->connection;
  22        struct device *dev = &connection->bundle->dev;
  23        struct gb_log_send_log_request *receive;
  24        u16 len;
  25
  26        if (op->type != GB_LOG_TYPE_SEND_LOG) {
  27                dev_err(dev, "unknown request type 0x%02x\n", op->type);
  28                return -EINVAL;
  29        }
  30
  31        /* Verify size of payload */
  32        if (op->request->payload_size < sizeof(*receive)) {
  33                dev_err(dev, "log request too small (%zu < %zu)\n",
  34                                op->request->payload_size, sizeof(*receive));
  35                return -EINVAL;
  36        }
  37        receive = op->request->payload;
  38        len = le16_to_cpu(receive->len);
  39        if (len != (op->request->payload_size - sizeof(*receive))) {
  40                dev_err(dev, "log request wrong size %d vs %zu\n", len,
  41                                (op->request->payload_size - sizeof(*receive)));
  42                return -EINVAL;
  43        }
  44        if (len == 0) {
  45                dev_err(dev, "log request of 0 bytes?\n");
  46                return -EINVAL;
  47        }
  48
  49        if (len > GB_LOG_MAX_LEN) {
  50                dev_err(dev, "log request too big: %d\n", len);
  51                return -EINVAL;
  52        }
  53
  54        /* Ensure the buffer is 0 terminated */
  55        receive->msg[len - 1] = '\0';
  56
  57        /*
  58         * Print with dev_dbg() so that it can be easily turned off using
  59         * dynamic debugging (and prevent any DoS)
  60         */
  61        dev_dbg(dev, "%s", receive->msg);
  62
  63        return 0;
  64}
  65
  66static int gb_log_probe(struct gb_bundle *bundle,
  67                        const struct greybus_bundle_id *id)
  68{
  69        struct greybus_descriptor_cport *cport_desc;
  70        struct gb_connection *connection;
  71        struct gb_log *log;
  72        int retval;
  73
  74        if (bundle->num_cports != 1)
  75                return -ENODEV;
  76
  77        cport_desc = &bundle->cport_desc[0];
  78        if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
  79                return -ENODEV;
  80
  81        log = kzalloc(sizeof(*log), GFP_KERNEL);
  82        if (!log)
  83                return -ENOMEM;
  84
  85        connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
  86                        gb_log_request_handler);
  87        if (IS_ERR(connection)) {
  88                retval = PTR_ERR(connection);
  89                goto error_free;
  90        }
  91
  92        log->connection = connection;
  93        greybus_set_drvdata(bundle, log);
  94
  95        retval = gb_connection_enable(connection);
  96        if (retval)
  97                goto error_connection_destroy;
  98
  99        return 0;
 100
 101error_connection_destroy:
 102        gb_connection_destroy(connection);
 103error_free:
 104        kfree(log);
 105        return retval;
 106}
 107
 108static void gb_log_disconnect(struct gb_bundle *bundle)
 109{
 110        struct gb_log *log = greybus_get_drvdata(bundle);
 111        struct gb_connection *connection = log->connection;
 112
 113        gb_connection_disable(connection);
 114        gb_connection_destroy(connection);
 115
 116        kfree(log);
 117}
 118
 119static const struct greybus_bundle_id gb_log_id_table[] = {
 120        { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
 121        { }
 122};
 123MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
 124
 125static struct greybus_driver gb_log_driver = {
 126        .name           = "log",
 127        .probe          = gb_log_probe,
 128        .disconnect     = gb_log_disconnect,
 129        .id_table       = gb_log_id_table,
 130};
 131module_greybus_driver(gb_log_driver);
 132
 133MODULE_LICENSE("GPL v2");
 134