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firewire: add isochronous multichannel reception

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This adds the DMA context programming and userspace ABI for multichannel
reception, i.e. for listening on multiple channel numbers by means of a
single DMA context.

The use case is reception of more streams than there are IR DMA units
offered by the link layer.  This is already implemented by the older
ohci1394 + ieee1394 + raw1394 stack.  And as discussed recently on
linux1394-devel, this feature is occasionally used in practice.

The big drawbacks of this mode are that buffer layout and interrupt
generation necessarily differ from single-channel reception:  Headers
and trailers are not stripped from packets, packets are not aligned with
buffer chunks, interrupts are per buffer chunk, not per packet.

These drawbacks also cause a rather hefty code footprint to support this
rarely used OHCI-1394 feature.  (367 lines added, among them 94 lines of
added userspace ABI documentation.)

This implementation enforces that a multichannel reception context may
only listen to channels to which no single-channel context on the same
link layer is presently listening to.  OHCI-1394 would allow to overlay
single-channel contexts by the multi-channel context, but this would be
a departure from the present first-come-first-served policy of IR
context creation.

The implementation is heavily based on an earlier one by Jay Fenlason.
Thanks Jay.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter
2010-07-29 18:19:22 +02:00
parent ae2a976614
commit 872e330e38
6 changed files with 561 additions and 194 deletions
Download Patch File Download Diff File Expand all files Collapse all files

277
include/linux/firewire-cdev.h
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@@ -25,17 +25,18 @@
#include <linux/types.h>
#include <linux/firewire-constants.h>
#define FW_CDEV_EVENT_BUS_RESET 0x00
#define FW_CDEV_EVENT_RESPONSE 0x01
#define FW_CDEV_EVENT_REQUEST 0x02
#define FW_CDEV_EVENT_ISO_INTERRUPT 0x03
#define FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED 0x04
#define FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED 0x05
#define FW_CDEV_EVENT_BUS_RESET 0x00
#define FW_CDEV_EVENT_RESPONSE 0x01
#define FW_CDEV_EVENT_REQUEST 0x02
#define FW_CDEV_EVENT_ISO_INTERRUPT 0x03
#define FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED 0x04
#define FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED 0x05
/* available since kernel version 2.6.36 */
#define FW_CDEV_EVENT_REQUEST2 0x06
#define FW_CDEV_EVENT_PHY_PACKET_SENT 0x07
#define FW_CDEV_EVENT_PHY_PACKET_RECEIVED 0x08
#define FW_CDEV_EVENT_REQUEST2 0x06
#define FW_CDEV_EVENT_PHY_PACKET_SENT 0x07
#define FW_CDEV_EVENT_PHY_PACKET_RECEIVED 0x08
#define FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL 0x09
/**
* struct fw_cdev_event_common - Common part of all fw_cdev_event_ types
@@ -218,35 +219,41 @@ struct fw_cdev_event_request2 {
* This event is sent when the controller has completed an &fw_cdev_iso_packet
* with the %FW_CDEV_ISO_INTERRUPT bit set.
*
* Isochronous transmit events:
* Isochronous transmit events (context type %FW_CDEV_ISO_CONTEXT_TRANSMIT):
*
* In version 1 of the ABI, &header_length is 0. In version 3 and some
* implementations of version 2 of the ABI, &header_length is a multiple of 4
* and &header contains timestamps of all packets up until the interrupt packet.
* The format of the timestamps is as described below for isochronous reception.
* In version 3 and some implementations of version 2 of the ABI, &header_length
* is a multiple of 4 and &header contains timestamps of all packets up until
* the interrupt packet. The format of the timestamps is as described below for
* isochronous reception. In version 1 of the ABI, &header_length was 0.
*
* Isochronous receive events:
* Isochronous receive events (context type %FW_CDEV_ISO_CONTEXT_RECEIVE):
*
* The headers stripped of all packets up until and including the interrupt
* packet are returned in the @header field. The amount of header data per
* packet is as specified at iso context creation by
* &fw_cdev_create_iso_context.header_size.
*
* In version 1 of this ABI, header data consisted of the 1394 isochronous
* packet header, followed by quadlets from the packet payload if
* &fw_cdev_create_iso_context.header_size > 4.
* Hence, _interrupt.header_length / _context.header_size is the number of
* packets received in this interrupt event. The client can now iterate
* through the mmap()'ed DMA buffer according to this number of packets and
* to the buffer sizes as the client specified in &fw_cdev_queue_iso.
*
* In version 2 of this ABI, header data consist of the 1394 isochronous
* packet header, followed by a timestamp quadlet if
* &fw_cdev_create_iso_context.header_size > 4, followed by quadlets from the
* packet payload if &fw_cdev_create_iso_context.header_size > 8.
* Since version 2 of this ABI, the portion for each packet in _interrupt.header
* consists of the 1394 isochronous packet header, followed by a timestamp
* quadlet if &fw_cdev_create_iso_context.header_size > 4, followed by quadlets
* from the packet payload if &fw_cdev_create_iso_context.header_size > 8.
*
* Format of 1394 iso packet header: 16 bits data_length, 2 bits tag, 6 bits
* channel, 4 bits tcode, 4 bits sy, in big endian byte order.
* data_length is the actual received size of the packet without the four
* 1394 iso packet header bytes.
*
* Format of timestamp: 16 bits invalid, 3 bits cycleSeconds, 13 bits
* cycleCount, in big endian byte order.
*
* In version 1 of the ABI, no timestamp quadlet was inserted; instead, payload
* data followed directly after the 1394 is header if header_size > 4.
* Behaviour of ver. 1 of this ABI is no longer available since ABI ver. 2.
*
* Format of 1394 iso packet header: 16 bits len, 2 bits tag, 6 bits channel,
* 4 bits tcode, 4 bits sy, in big endian byte order. Format of timestamp:
* 16 bits invalid, 3 bits cycleSeconds, 13 bits cycleCount, in big endian byte
* order.
*/
struct fw_cdev_event_iso_interrupt {
__u64 closure;
@@ -256,6 +263,43 @@ struct fw_cdev_event_iso_interrupt {
__u32 header[0];
};
/**
* struct fw_cdev_event_iso_interrupt_mc - An iso buffer chunk was completed
* @closure: See &fw_cdev_event_common;
* set by %FW_CDEV_CREATE_ISO_CONTEXT ioctl
* @type: %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL
* @completed: Offset into the receive buffer; data before this offest is valid
*
* This event is sent in multichannel contexts (context type
* %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL) for &fw_cdev_iso_packet buffer
* chunks that have the %FW_CDEV_ISO_INTERRUPT bit set. Whether this happens
* when a packet is completed and/or when a buffer chunk is completed depends
* on the hardware implementation.
*
* The buffer is continuously filled with the following data, per packet:
* - the 1394 iso packet header as described at &fw_cdev_event_iso_interrupt,
* but in little endian byte order,
* - packet payload (as many bytes as specified in the data_length field of
* the 1394 iso packet header) in big endian byte order,
* - 0...3 padding bytes as needed to align the following trailer quadlet,
* - trailer quadlet, containing the reception timestamp as described at
* &fw_cdev_event_iso_interrupt, but in little endian byte order.
*
* Hence the per-packet size is data_length (rounded up to a multiple of 4) + 8.
* When processing the data, stop before a packet that would cross the
* @completed offset.
*
* A packet near the end of a buffer chunk will typically spill over into the
* next queued buffer chunk. It is the responsibility of the client to check
* for this condition, assemble a broken-up packet from its parts, and not to
* re-queue any buffer chunks in which as yet unread packet parts reside.
*/
struct fw_cdev_event_iso_interrupt_mc {
__u64 closure;
__u32 type;
__u32 completed;
};
/**
* struct fw_cdev_event_iso_resource - Iso resources were allocated or freed
* @closure: See &fw_cdev_event_common;
@@ -311,16 +355,18 @@ struct fw_cdev_event_phy_packet {
/**
* union fw_cdev_event - Convenience union of fw_cdev_event_ types
* @common: Valid for all types
* @bus_reset: Valid if @common.type == %FW_CDEV_EVENT_BUS_RESET
* @response: Valid if @common.type == %FW_CDEV_EVENT_RESPONSE
* @request: Valid if @common.type == %FW_CDEV_EVENT_REQUEST
* @request2: Valid if @common.type == %FW_CDEV_EVENT_REQUEST2
* @iso_interrupt: Valid if @common.type == %FW_CDEV_EVENT_ISO_INTERRUPT
* @iso_resource: Valid if @common.type ==
* @common: Valid for all types
* @bus_reset: Valid if @common.type == %FW_CDEV_EVENT_BUS_RESET
* @response: Valid if @common.type == %FW_CDEV_EVENT_RESPONSE
* @request: Valid if @common.type == %FW_CDEV_EVENT_REQUEST
* @request2: Valid if @common.type == %FW_CDEV_EVENT_REQUEST2
* @iso_interrupt: Valid if @common.type == %FW_CDEV_EVENT_ISO_INTERRUPT
* @iso_interrupt_mc: Valid if @common.type ==
* %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL
* @iso_resource: Valid if @common.type ==
* %FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED or
* %FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED
* @phy_packet: Valid if @common.type ==
* @phy_packet: Valid if @common.type ==
* %FW_CDEV_EVENT_PHY_PACKET_SENT or
* %FW_CDEV_EVENT_PHY_PACKET_RECEIVED
*
@@ -337,10 +383,11 @@ union fw_cdev_event {
struct fw_cdev_event_bus_reset bus_reset;
struct fw_cdev_event_response response;
struct fw_cdev_event_request request;
struct fw_cdev_event_request2 request2; /* added in 2.6.36 */
struct fw_cdev_event_request2 request2; /* added in 2.6.36 */
struct fw_cdev_event_iso_interrupt iso_interrupt;
struct fw_cdev_event_iso_resource iso_resource; /* added in 2.6.30 */
struct fw_cdev_event_phy_packet phy_packet; /* added in 2.6.36 */
struct fw_cdev_event_iso_interrupt_mc iso_interrupt_mc; /* added in 2.6.36 */
struct fw_cdev_event_iso_resource iso_resource; /* added in 2.6.30 */
struct fw_cdev_event_phy_packet phy_packet; /* added in 2.6.36 */
};
/* available since kernel version 2.6.22 */
@@ -375,6 +422,7 @@ union fw_cdev_event {
/* available since kernel version 2.6.36 */
#define FW_CDEV_IOC_SEND_PHY_PACKET _IOWR('#', 0x15, struct fw_cdev_send_phy_packet)
#define FW_CDEV_IOC_RECEIVE_PHY_PACKETS _IOW('#', 0x16, struct fw_cdev_receive_phy_packets)
#define FW_CDEV_IOC_SET_ISO_CHANNELS _IOW('#', 0x17, struct fw_cdev_set_iso_channels)
/*
* ABI version history
@@ -391,10 +439,13 @@ union fw_cdev_event {
* - shared use and auto-response for FCP registers
* 3 (2.6.34) - made &fw_cdev_get_cycle_timer reliable
* - added %FW_CDEV_IOC_GET_CYCLE_TIMER2
* 4 (2.6.36) - added %FW_CDEV_EVENT_REQUEST2, %FW_CDEV_EVENT_PHY_PACKET_*
* 4 (2.6.36) - added %FW_CDEV_EVENT_REQUEST2, %FW_CDEV_EVENT_PHY_PACKET_*,
* and &fw_cdev_allocate.region_end
* - implemented &fw_cdev_event_bus_reset.bm_node_id
* - added %FW_CDEV_IOC_SEND_PHY_PACKET, _RECEIVE_PHY_PACKETS
* - added &fw_cdev_allocate.region_end
* - added %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL,
* %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL, and
* %FW_CDEV_IOC_SET_ISO_CHANNELS
*/
#define FW_CDEV_VERSION 3 /* Meaningless; don't use this macro. */
@@ -597,34 +648,43 @@ struct fw_cdev_remove_descriptor {
__u32 handle;
};
#define FW_CDEV_ISO_CONTEXT_TRANSMIT 0
#define FW_CDEV_ISO_CONTEXT_RECEIVE 1
#define FW_CDEV_ISO_CONTEXT_TRANSMIT 0
#define FW_CDEV_ISO_CONTEXT_RECEIVE 1
#define FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL 2 /* added in 2.6.36 */
/**
* struct fw_cdev_create_iso_context - Create a context for isochronous IO
* @type: %FW_CDEV_ISO_CONTEXT_TRANSMIT or %FW_CDEV_ISO_CONTEXT_RECEIVE
* @header_size: Header size to strip for receive contexts
* @channel: Channel to bind to
* @speed: Speed for transmit contexts
* @closure: To be returned in &fw_cdev_event_iso_interrupt
* struct fw_cdev_create_iso_context - Create a context for isochronous I/O
* @type: %FW_CDEV_ISO_CONTEXT_TRANSMIT or %FW_CDEV_ISO_CONTEXT_RECEIVE or
* %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL
* @header_size: Header size to strip in single-channel reception
* @channel: Channel to bind to in single-channel reception or transmission
* @speed: Transmission speed
* @closure: To be returned in &fw_cdev_event_iso_interrupt or
* &fw_cdev_event_iso_interrupt_multichannel
* @handle: Handle to context, written back by kernel
*
* Prior to sending or receiving isochronous I/O, a context must be created.
* The context records information about the transmit or receive configuration
* and typically maps to an underlying hardware resource. A context is set up
* for either sending or receiving. It is bound to a specific isochronous
* channel.
* @channel.
*
* In case of multichannel reception, @header_size and @channel are ignored
* and the channels are selected by %FW_CDEV_IOC_SET_ISO_CHANNELS.
*
* For %FW_CDEV_ISO_CONTEXT_RECEIVE contexts, @header_size must be at least 4
* and must be a multiple of 4. It is ignored in other context types.
*
* @speed is ignored in receive context types.
*
* If a context was successfully created, the kernel writes back a handle to the
* context, which must be passed in for subsequent operations on that context.
*
* For receive contexts, @header_size must be at least 4 and must be a multiple
* of 4.
*
* Note that the effect of a @header_size > 4 depends on
* &fw_cdev_get_info.version, as documented at &fw_cdev_event_iso_interrupt.
*
* Limitations:
* No more than one iso context can be created per fd.
* The total number of contexts that all userspace and kernelspace drivers can
* create on a card at a time is a hardware limit, typically 4 or 8 contexts per
* direction, and of them at most one multichannel receive context.
*/
struct fw_cdev_create_iso_context {
__u32 type;
@@ -635,6 +695,22 @@ struct fw_cdev_create_iso_context {
__u32 handle;
};
/**
* struct fw_cdev_set_iso_channels - Select channels in multichannel reception
* @channels: Bitmask of channels to listen to
* @handle: Handle of the mutichannel receive context
*
* @channels is the bitwise or of 1ULL << n for each channel n to listen to.
*
* The ioctl fails with errno %EBUSY if there is already another receive context
* on a channel in @channels. In that case, the bitmask of all unoccupied
* channels is returned in @channels.
*/
struct fw_cdev_set_iso_channels {
__u64 channels;
__u32 handle;
};
#define FW_CDEV_ISO_PAYLOAD_LENGTH(v) (v)
#define FW_CDEV_ISO_INTERRUPT (1 << 16)
#define FW_CDEV_ISO_SKIP (1 << 17)
@@ -645,42 +721,72 @@ struct fw_cdev_create_iso_context {
/**
* struct fw_cdev_iso_packet - Isochronous packet
* @control: Contains the header length (8 uppermost bits), the sy field
* (4 bits), the tag field (2 bits), a sync flag (1 bit),
* a skip flag (1 bit), an interrupt flag (1 bit), and the
* @control: Contains the header length (8 uppermost bits),
* the sy field (4 bits), the tag field (2 bits), a sync flag
* or a skip flag (1 bit), an interrupt flag (1 bit), and the
* payload length (16 lowermost bits)
* @header: Header and payload
* @header: Header and payload in case of a transmit context.
*
* &struct fw_cdev_iso_packet is used to describe isochronous packet queues.
*
* Use the FW_CDEV_ISO_ macros to fill in @control.
* The @header array is empty in case of receive contexts.
*
* For transmit packets, the header length must be a multiple of 4 and specifies
* the numbers of bytes in @header that will be prepended to the packet's
* payload; these bytes are copied into the kernel and will not be accessed
* after the ioctl has returned. The sy and tag fields are copied to the iso
* packet header (these fields are specified by IEEE 1394a and IEC 61883-1).
* The skip flag specifies that no packet is to be sent in a frame; when using
* this, all other fields except the interrupt flag must be zero.
* Context type %FW_CDEV_ISO_CONTEXT_TRANSMIT:
*
* For receive packets, the header length must be a multiple of the context's
* header size; if the header length is larger than the context's header size,
* multiple packets are queued for this entry. The sy and tag fields are
* ignored. If the sync flag is set, the context drops all packets until
* a packet with a matching sy field is received (the sync value to wait for is
* specified in the &fw_cdev_start_iso structure). The payload length defines
* how many payload bytes can be received for one packet (in addition to payload
* quadlets that have been defined as headers and are stripped and returned in
* the &fw_cdev_event_iso_interrupt structure). If more bytes are received, the
* additional bytes are dropped. If less bytes are received, the remaining
* bytes in this part of the payload buffer will not be written to, not even by
* the next packet, i.e., packets received in consecutive frames will not
* necessarily be consecutive in memory. If an entry has queued multiple
* packets, the payload length is divided equally among them.
* @control.HEADER_LENGTH must be a multiple of 4. It specifies the numbers of
* bytes in @header that will be prepended to the packet's payload. These bytes
* are copied into the kernel and will not be accessed after the ioctl has
* returned.
*
* When a packet with the interrupt flag set has been completed, the
* The @control.SY and TAG fields are copied to the iso packet header. These
* fields are specified by IEEE 1394a and IEC 61883-1.
*
* The @control.SKIP flag specifies that no packet is to be sent in a frame.
* When using this, all other fields except @control.INTERRUPT must be zero.
*
* When a packet with the @control.INTERRUPT flag set has been completed, an
* &fw_cdev_event_iso_interrupt event will be sent.
*
* Context type %FW_CDEV_ISO_CONTEXT_RECEIVE:
*
* @control.HEADER_LENGTH must be a multiple of the context's header_size.
* If the HEADER_LENGTH is larger than the context's header_size, multiple
* packets are queued for this entry.
*
* The @control.SY and TAG fields are ignored.
*
* If the @control.SYNC flag is set, the context drops all packets until a
* packet with a sy field is received which matches &fw_cdev_start_iso.sync.
*
* @control.PAYLOAD_LENGTH defines how many payload bytes can be received for
* one packet (in addition to payload quadlets that have been defined as headers
* and are stripped and returned in the &fw_cdev_event_iso_interrupt structure).
* If more bytes are received, the additional bytes are dropped. If less bytes
* are received, the remaining bytes in this part of the payload buffer will not
* be written to, not even by the next packet. I.e., packets received in
* consecutive frames will not necessarily be consecutive in memory. If an
* entry has queued multiple packets, the PAYLOAD_LENGTH is divided equally
* among them.
*
* When a packet with the @control.INTERRUPT flag set has been completed, an
* &fw_cdev_event_iso_interrupt event will be sent. An entry that has queued
* multiple receive packets is completed when its last packet is completed.
*
* Context type %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL:
*
* Here, &fw_cdev_iso_packet would be more aptly named _iso_buffer_chunk since
* it specifies a chunk of the mmap()'ed buffer, while the number and alignment
* of packets to be placed into the buffer chunk is not known beforehand.
*
* @control.PAYLOAD_LENGTH is the size of the buffer chunk and specifies room
* for header, payload, padding, and trailer bytes of one or more packets.
* It must be a multiple of 4.
*
* @control.HEADER_LENGTH, TAG and SY are ignored. SYNC is treated as described
* for single-channel reception.
*
* When a buffer chunk with the @control.INTERRUPT flag set has been filled
* entirely, an &fw_cdev_event_iso_interrupt_mc event will be sent.
*/
struct fw_cdev_iso_packet {
__u32 control;
@@ -689,9 +795,9 @@ struct fw_cdev_iso_packet {
/**
* struct fw_cdev_queue_iso - Queue isochronous packets for I/O
* @packets: Userspace pointer to packet data
* @packets: Userspace pointer to an array of &fw_cdev_iso_packet
* @data: Pointer into mmap()'ed payload buffer
* @size: Size of packet data in bytes
* @size: Size of the @packets array, in bytes
* @handle: Isochronous context handle
*
* Queue a number of isochronous packets for reception or transmission.
@@ -704,6 +810,9 @@ struct fw_cdev_iso_packet {
* The kernel may or may not queue all packets, but will write back updated
* values of the @packets, @data and @size fields, so the ioctl can be
* resubmitted easily.
*
* In case of a multichannel receive context, @data must be quadlet-aligned
* relative to the buffer start.
*/
struct fw_cdev_queue_iso {
__u64 packets;