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1// SPDX-License-Identifier: GPL-2.02/*3 * Greybus driver for the log protocol4 *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 using58 * 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_DESCRIPTION("Greybus driver for the log protocol");133MODULE_LICENSE("GPL v2");134