CAN Device Driver Internals

Pavel Pisa

pisa@cmp.felk.cvut.cz

Table of Contents

Introduction

LinCAN Driver API

Driver API Overview

CAN Driver File Operations

open — message communication object open system call
close — message communication object close system call
read — reads received CAN messages from message object
write — writes CAN messages to message object for transmission

Driver Internal Documentation

Basic Driver Data Structures

struct canhardware_t — structure representing pointers to all CAN boards
struct candevice_t — CAN device/board structure
struct chip_t — CAN chip state and type information
struct msgobj_t — structure holding communication object state
struct canuser_t — structure holding CAN user/client state
struct hwspecops_t — hardware/board specific operations
struct chipspecops_t — can controller chip specific operations

Board Support Functions

template_request_io — reserve io or memory range for can board
template_release_io — free reserved io memory range
template_reset — hardware reset routine
template_init_hw_data — Initialize hardware cards
template_init_chip_data — Initialize chips
template_init_obj_data — Initialize message buffers
template_program_irq — program interrupts
template_write_register — Low level write register routine
template_read_register — Low level read register routine

Chip Support Functions

sja1000p_enable_configuration — enable chip configuration mode
sja1000p_disable_configuration — disable chip configuration mode
sja1000p_chip_config — can chip configuration
sja1000p_extended_mask — setup of extended mask for message filtering
sja1000p_baud_rate — set communication parameters.
sja1000p_read — reads and distributes one or more received messages
sja1000p_pre_read_config — prepares message object for message reception
sja1000p_pre_write_config — prepares message object for message transmission
sja1000p_send_msg — initiate message transmission
sja1000p_check_tx_stat — checks state of transmission engine
sja1000p_set_btregs — configures bitrate registers
sja1000p_start_chip — starts chip message processing
sja1000p_stop_chip — stops chip message processing
sja1000p_remote_request — configures message object and asks for RTR message
sja1000p_standard_mask — setup of mask for message filtering
sja1000p_clear_objects — clears state of all message object residing in chip
sja1000p_config_irqs — tunes chip hardware interrupt delivery
sja1000p_irq_write_handler — part of ISR code responsible for transmit events
sja1000p_irq_handler — interrupt service routine
sja1000p_wakeup_tx — wakeups TX processing

CAN Queues Structures and Functions

struct canque_slot_t — one CAN message slot in the CAN FIFO queue
struct canque_fifo_t — CAN FIFO queue representation
canque_fifo_get_inslot — allocate slot for the input of one CAN message
canque_fifo_put_inslot — releases slot to further processing
canque_fifo_abort_inslot — release and abort slot
canque_fifo_test_outslot — test and get ready slot from the FIFO
canque_fifo_free_outslot — free processed FIFO slot
canque_fifo_again_outslot — interrupt and postpone processing of the slot
struct canque_edge_t — CAN message delivery subsystem graph edge
struct canque_ends_t — CAN message delivery subsystem graph vertex (FIFO ends)
canque_notify_inends — request to send notification to the input ends
canque_notify_outends — request to send notification to the output ends
canque_notify_bothends — request to send notification to the both ends
canque_activate_edge — mark output end of the edge as active
canque_filtid2internal — converts message ID and filter flags into internal format
canque_fifo_flush_slots — free all ready slots from the FIFO
canque_fifo_init_slots — initialize one CAN FIFO
canque_fifo_done — frees slots allocated for CAN FIFO
canque_get_inslot — finds one outgoing edge and allocates slot from it
canque_get_inslot4id — finds best outgoing edge and slot for given ID
canque_put_inslot — schedules filled slot for processing
canque_abort_inslot — aborts preparation of the message in the slot
canque_filter_msg2edges — sends message into all edges which accept its ID
canque_test_outslot — test and retrieve ready slot for given ends
canque_free_outslot — frees processed output slot
canque_again_outslot — reschedule output slot to process it again later
canque_set_filt — sets filter for specified edge
canque_flush — fluesh all ready slots in the edge
canqueue_ends_init_gen — subsystem independent routine to initialize ends state
canqueue_notify_kern — notification callback handler for Linux userspace clients
canqueue_ends_init_kern — Linux userspace clients specific ends initialization
canque_get_inslot4id_wait_kern — find or wait for best outgoing edge and slot for given ID
canque_get_outslot_wait_kern — receive or wait for ready slot for given ends
canque_sync_wait_kern — wait for all slots processing
canque_new_edge_kern — allocate new edge structure in the Linux kernel context
canqueue_connect_edge — connect edge between two communication entities
canqueue_disconnect_edge — disconnect edge from communicating entities
canqueue_disconnect_edge_kern — disconnect edge from communicating entities with wait
canqueue_ends_done_kern — finalizing of the ends structure for Linux kernel clients

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