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

   1/*
   2 * Greybus driver for the log protocol
   3 *
   4 * Copyright 2016 Google Inc.
   5 *
   6 * Released under the GPLv2 only.
   7 */
   8#include <linux/kernel.h>
   9#include <linux/module.h>
  10#include <linux/slab.h>
  11#include <linux/sizes.h>
  12#include <linux/uaccess.h>
  13
  14#include "greybus.h"
  15
  16struct gb_log {
  17        struct gb_connection *connection;
  18};
  19
  20static int gb_log_request_handler(struct gb_operation *op)
  21{
  22        struct gb_connection *connection = op->connection;
  23        struct device *dev = &connection->bundle->dev;
  24        struct gb_log_send_log_request *receive;
  25        u16 len;
  26
  27        if (op->type != GB_LOG_TYPE_SEND_LOG) {
  28                dev_err(dev, "unknown request type 0x%02x\n", op->type);
  29                return -EINVAL;
  30        }
  31
  32        /* Verify size of payload */
  33        if (op->request->payload_size < sizeof(*receive)) {
  34                dev_err(dev, "log request too small (%zu < %zu)\n",
  35                                op->request->payload_size, sizeof(*receive));
  36                return -EINVAL;
  37        }
  38        receive = op->request->payload;
  39        len = le16_to_cpu(receive->len);
  40        if (len != (op->request->payload_size - sizeof(*receive))) {
  41                dev_err(dev, "log request wrong size %d vs %zu\n", len,
  42                                (op->request->payload_size - sizeof(*receive)));
  43                return -EINVAL;
  44        }
  45        if (len == 0) {
  46                dev_err(dev, "log request of 0 bytes?\n");
  47                return -EINVAL;
  48        }
  49
  50        if (len > GB_LOG_MAX_LEN) {
  51                dev_err(dev, "log request too big: %d\n", len);
  52                return -EINVAL;
  53        }
  54
  55        /* Ensure the buffer is 0 terminated */
  56        receive->msg[len - 1] = '\0';
  57
  58        /*
  59         * Print with dev_dbg() so that it can be easily turned off using
  60         * dynamic debugging (and prevent any DoS)
  61         */
  62        dev_dbg(dev, "%s", receive->msg);
  63
  64        return 0;
  65}
  66
  67static int gb_log_probe(struct gb_bundle *bundle,
  68                        const struct greybus_bundle_id *id)
  69{
  70        struct greybus_descriptor_cport *cport_desc;
  71        struct gb_connection *connection;
  72        struct gb_log *log;
  73        int retval;
  74
  75        if (bundle->num_cports != 1)
  76                return -ENODEV;
  77
  78        cport_desc = &bundle->cport_desc[0];
  79        if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
  80                return -ENODEV;
  81
  82        log = kzalloc(sizeof(*log), GFP_KERNEL);
  83        if (!log)
  84                return -ENOMEM;
  85
  86        connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
  87                        gb_log_request_handler);
  88        if (IS_ERR(connection)) {
  89                retval = PTR_ERR(connection);
  90                goto error_free;
  91        }
  92
  93        log->connection = connection;
  94        greybus_set_drvdata(bundle, log);
  95
  96        retval = gb_connection_enable(connection);
  97        if (retval)
  98                goto error_connection_destroy;
  99
 100        return 0;
 101
 102error_connection_destroy:
 103        gb_connection_destroy(connection);
 104error_free:
 105        kfree(log);
 106        return retval;
 107}
 108
 109static void gb_log_disconnect(struct gb_bundle *bundle)
 110{
 111        struct gb_log *log = greybus_get_drvdata(bundle);
 112        struct gb_connection *connection = log->connection;
 113
 114        gb_connection_disable(connection);
 115        gb_connection_destroy(connection);
 116
 117        kfree(log);
 118}
 119
 120static const struct greybus_bundle_id gb_log_id_table[] = {
 121        { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
 122        { }
 123};
 124MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
 125
 126static struct greybus_driver gb_log_driver = {
 127        .name           = "log",
 128        .probe          = gb_log_probe,
 129        .disconnect     = gb_log_disconnect,
 130        .id_table       = gb_log_id_table,
 131};
 132module_greybus_driver(gb_log_driver);
 133
 134MODULE_LICENSE("GPL v2");
 135