firewire: Document userspace ioctl interface.
The isochronous packet format is still not documented, but this
is a good first step.
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (format, wording)
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index efbe1fd..1a45d6f 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -30,16 +30,38 @@
#define FW_CDEV_EVENT_REQUEST 0x02
#define FW_CDEV_EVENT_ISO_INTERRUPT 0x03
-/* The 'closure' fields are for user space to use. Data passed in the
- * 'closure' field for a request will be returned in the corresponding
- * event. It's a 64-bit type so that it's a fixed size type big
- * enough to hold a pointer on all platforms. */
-
+/**
+ * struct fw_cdev_event_common - Common part of all fw_cdev_event_ types
+ * @closure: For arbitrary use by userspace
+ * @type: Discriminates the fw_cdev_event_ types
+ *
+ * This struct may be used to access generic members of all fw_cdev_event_
+ * types regardless of the specific type.
+ *
+ * Data passed in the @closure field for a request will be returned in the
+ * corresponding event. It is big enough to hold a pointer on all platforms.
+ * The ioctl used to set @closure depends on the @type of event.
+ */
struct fw_cdev_event_common {
__u64 closure;
__u32 type;
};
+/**
+ * struct fw_cdev_event_bus_reset - Sent when a bus reset occurred
+ * @closure: See &fw_cdev_event_common; set by %FW_CDEV_IOC_GET_INFO ioctl
+ * @type: See &fw_cdev_event_common; always %FW_CDEV_EVENT_BUS_RESET
+ * @node_id: New node ID of this node
+ * @local_node_id: Node ID of the local node, i.e. of the controller
+ * @bm_node_id: Node ID of the bus manager
+ * @irm_node_id: Node ID of the iso resource manager
+ * @root_node_id: Node ID of the root node
+ * @generation: New bus generation
+ *
+ * This event is sent when the bus the device belongs to goes through a bus
+ * reset. It provides information about the new bus configuration, such as
+ * new node ID for this device, new root ID, and others.
+ */
struct fw_cdev_event_bus_reset {
__u64 closure;
__u32 type;
@@ -51,6 +73,20 @@
__u32 generation;
};
+/**
+ * struct fw_cdev_event_response - Sent when a response packet was received
+ * @closure: See &fw_cdev_event_common;
+ * set by %FW_CDEV_IOC_SEND_REQUEST ioctl
+ * @type: See &fw_cdev_event_common; always %FW_CDEV_EVENT_RESPONSE
+ * @rcode: Response code returned by the remote node
+ * @length: Data length, i.e. the response's payload size in bytes
+ * @data: Payload data, if any
+ *
+ * This event is sent when the stack receives a response to an outgoing request
+ * sent by %FW_CDEV_IOC_SEND_REQUEST ioctl. The payload data for responses
+ * carrying data (read and lock responses) follows immediately and can be
+ * accessed through the @data field.
+ */
struct fw_cdev_event_response {
__u64 closure;
__u32 type;
@@ -59,6 +95,25 @@
__u32 data[0];
};
+/**
+ * struct fw_cdev_event_request - Sent on incoming request to an address region
+ * @closure: See &fw_cdev_event_common; set by %FW_CDEV_IOC_ALLOCATE ioctl
+ * @type: See &fw_cdev_event_common; always %FW_CDEV_EVENT_REQUEST
+ * @tcode: Transaction code of the incoming request
+ * @offset: The offset into the 48-bit per-node address space
+ * @handle: Reference to the kernel-side pending request
+ * @length: Data length, i.e. the request's payload size in bytes
+ * @data: Incoming data, if any
+ *
+ * This event is sent when the stack receives an incoming request to an address
+ * region registered using the %FW_CDEV_IOC_ALLOCATE ioctl. The request is
+ * guaranteed to be completely contained in the specified region. Userspace is
+ * responsible for sending the response by %FW_CDEV_IOC_SEND_RESPONSE ioctl,
+ * using the same @handle.
+ *
+ * The payload data for requests carrying data (write and lock requests)
+ * follows immediately and can be accessed through the @data field.
+ */
struct fw_cdev_event_request {
__u64 closure;
__u32 type;
@@ -69,14 +124,39 @@
__u32 data[0];
};
+/**
+ * struct fw_cdev_event_iso_interrupt - Sent when an iso packet was completed
+ * @closure: See &fw_cdev_event_common;
+ * set by %FW_CDEV_CREATE_ISO_CONTEXT ioctl
+ * @type: See &fw_cdev_event_common; always %FW_CDEV_EVENT_ISO_INTERRUPT
+ * @cycle: Cycle counter of the interrupt packet
+ * @header_length: Total length of following headers, in bytes
+ * @header: Stripped headers, if any
+ *
+ * This event is sent when the controller has completed an &fw_cdev_iso_packet
+ * with the %FW_CDEV_ISO_INTERRUPT bit set. In the receive case, the headers
+ * stripped of all packets up until and including the interrupt packet are
+ * returned in the @header field.
+ */
struct fw_cdev_event_iso_interrupt {
__u64 closure;
__u32 type;
__u32 cycle;
- __u32 header_length; /* Length in bytes of following headers. */
+ __u32 header_length;
__u32 header[0];
};
+/**
+ * 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
+ * @iso_interrupt: Valid if @common.type == %FW_CDEV_EVENT_ISO_INTERRUPT
+ *
+ * Convenience union for userspace use. Events could be read(2) into a char
+ * buffer and then cast to this union for further processing.
+ */
union fw_cdev_event {
struct fw_cdev_event_common common;
struct fw_cdev_event_bus_reset bus_reset;
@@ -105,35 +185,47 @@
*/
#define FW_CDEV_VERSION 1
+/**
+ * struct fw_cdev_get_info - General purpose information ioctl
+ * @version: The version field is just a running serial number.
+ * We never break backwards compatibility, but may add more
+ * structs and ioctls in later revisions.
+ * @rom_length: If @rom is non-zero, at most rom_length bytes of configuration
+ * ROM will be copied into that user space address. In either
+ * case, @rom_length is updated with the actual length of the
+ * configuration ROM.
+ * @rom: If non-zero, address of a buffer to be filled by a copy of the
+ * local node's configuration ROM
+ * @bus_reset: If non-zero, address of a buffer to be filled by a
+ * &struct fw_cdev_event_bus_reset with the current state
+ * of the bus. This does not cause a bus reset to happen.
+ * @bus_reset_closure: Value of &closure in this and subsequent bus reset events
+ * @card: The index of the card this device belongs to
+ */
struct fw_cdev_get_info {
- /* The version field is just a running serial number. We
- * never break backwards compatibility. Userspace passes in
- * the version it expects and the kernel passes back the
- * highest version it can provide. Even if the structs in
- * this interface are extended in a later version, the kernel
- * will not copy back more data than what was present in the
- * interface version userspace expects. */
__u32 version;
-
- /* If non-zero, at most rom_length bytes of config rom will be
- * copied into that user space address. In either case,
- * rom_length is updated with the actual length of the config
- * rom. */
__u32 rom_length;
__u64 rom;
-
- /* If non-zero, a fw_cdev_event_bus_reset struct will be
- * copied here with the current state of the bus. This does
- * not cause a bus reset to happen. The value of closure in
- * this and sub-sequent bus reset events is set to
- * bus_reset_closure. */
__u64 bus_reset;
__u64 bus_reset_closure;
-
- /* The index of the card this devices belongs to. */
__u32 card;
};
+/**
+ * struct fw_cdev_send_request - Send an asynchronous request packet
+ * @tcode: Transaction code of the request
+ * @length: Length of outgoing payload, in bytes
+ * @offset: 48-bit offset at destination node
+ * @closure: Passed back to userspace in the response event
+ * @data: Userspace pointer to payload
+ * @generation: The bus generation where packet is valid
+ *
+ * Send a request to the device. This ioctl implements all outgoing requests.
+ * Both quadlet and block request specify the payload as a pointer to the data
+ * in the @data field. Once the transaction completes, the kernel writes an
+ * &fw_cdev_event_request event back. The @closure field is passed back to
+ * user space in the response event.
+ */
struct fw_cdev_send_request {
__u32 tcode;
__u32 length;
@@ -143,6 +235,19 @@
__u32 generation;
};
+/**
+ * struct fw_cdev_send_response - Send an asynchronous response packet
+ * @rcode: Response code as determined by the userspace handler
+ * @length: Length of outgoing payload, in bytes
+ * @data: Userspace pointer to payload
+ * @handle: The handle from the &fw_cdev_event_request
+ *
+ * Send a response to an incoming request. By setting up an address range using
+ * the %FW_CDEV_IOC_ALLOCATE ioctl, userspace can listen for incoming requests. An
+ * incoming request will generate an %FW_CDEV_EVENT_REQUEST, and userspace must
+ * send a reply using this ioctl. The event has a handle to the kernel-side
+ * pending transaction, which should be used with this ioctl.
+ */
struct fw_cdev_send_response {
__u32 rcode;
__u32 length;
@@ -150,6 +255,21 @@
__u32 handle;
};
+/**
+ * struct fw_cdev_allocate - Allocate a CSR address range
+ * @offset: Start offset of the address range
+ * @closure: To be passed back to userspace in request events
+ * @length: Length of the address range, in bytes
+ * @handle: Handle to the allocation, written by the kernel
+ *
+ * Allocate an address range in the 48-bit address space on the local node
+ * (the controller). This allows userspace to listen for requests with an
+ * offset within that address range. When the kernel receives a request
+ * within the range, an &fw_cdev_event_request event will be written back.
+ * The @closure field is passed back to userspace in the response event.
+ * The @handle field is an out parameter, returning a handle to the allocated
+ * range to be used for later deallocation of the range.
+ */
struct fw_cdev_allocate {
__u64 offset;
__u64 closure;
@@ -157,6 +277,11 @@
__u32 handle;
};
+/**
+ * struct fw_cdev_deallocate - Free an address range allocation
+ * @handle: Handle to the address range, as returned by the kernel when the
+ * range was allocated
+ */
struct fw_cdev_deallocate {
__u32 handle;
};
@@ -164,10 +289,41 @@
#define FW_CDEV_LONG_RESET 0
#define FW_CDEV_SHORT_RESET 1
+/**
+ * struct fw_cdev_initiate_bus_reset - Initiate a bus reset
+ * @type: %FW_CDEV_SHORT_RESET or %FW_CDEV_LONG_RESET
+ *
+ * Initiate a bus reset for the bus this device is on. The bus reset can be
+ * either the original (long) bus reset or the arbitrated (short) bus reset
+ * introduced in 1394a-2000.
+ */
struct fw_cdev_initiate_bus_reset {
- __u32 type;
+ __u32 type; /* FW_CDEV_SHORT_RESET or FW_CDEV_LONG_RESET */
};
+/**
+ * struct fw_cdev_add_descriptor - Add contents to the local node's config ROM
+ * @immediate: If non-zero, immediate key to insert before pointer
+ * @key: Upper 8 bits of root directory pointer
+ * @data: Userspace pointer to contents of descriptor block
+ * @length: Length of descriptor block data, in bytes
+ * @handle: Handle to the descriptor, written by the kernel
+ *
+ * Add a descriptor block and optionally a preceding immediate key to the local
+ * node's configuration ROM.
+ *
+ * The @key field specifies the upper 8 bits of the descriptor root directory
+ * pointer and the @data and @length fields specify the contents. The @key
+ * should be of the form 0xXX000000. The offset part of the root directory entry
+ * will be filled in by the kernel.
+ *
+ * If not 0, the @immediate field specifies an immediate key which will be
+ * inserted before the root directory pointer.
+ *
+ * If successful, the kernel adds the descriptor and writes back a handle to the
+ * kernel-side object to be used for later removal of the descriptor block and
+ * immediate key.
+ */
struct fw_cdev_add_descriptor {
__u32 immediate;
__u32 key;
@@ -176,6 +332,14 @@
__u32 handle;
};
+/**
+ * struct fw_cdev_remove_descriptor - Remove contents from the configuration ROM
+ * @handle: Handle to the descriptor, as returned by the kernel when the
+ * descriptor was added
+ *
+ * Remove a descriptor block and accompanying immediate key from the local
+ * node's configuration ROM.
+ */
struct fw_cdev_remove_descriptor {
__u32 handle;
};
@@ -183,12 +347,24 @@
#define FW_CDEV_ISO_CONTEXT_TRANSMIT 0
#define FW_CDEV_ISO_CONTEXT_RECEIVE 1
-#define FW_CDEV_ISO_CONTEXT_MATCH_TAG0 1
-#define FW_CDEV_ISO_CONTEXT_MATCH_TAG1 2
-#define FW_CDEV_ISO_CONTEXT_MATCH_TAG2 4
-#define FW_CDEV_ISO_CONTEXT_MATCH_TAG3 8
-#define FW_CDEV_ISO_CONTEXT_MATCH_ALL_TAGS 15
-
+/**
+ * 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 to transmit at
+ * @closure: To be returned in &fw_cdev_event_iso_interrupt
+ * @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.
+ *
+ * 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.
+ */
struct fw_cdev_create_iso_context {
__u32 type;
__u32 header_size;
@@ -201,15 +377,49 @@
#define FW_CDEV_ISO_PAYLOAD_LENGTH(v) (v)
#define FW_CDEV_ISO_INTERRUPT (1 << 16)
#define FW_CDEV_ISO_SKIP (1 << 17)
+#define FW_CDEV_ISO_SYNC (1 << 17)
#define FW_CDEV_ISO_TAG(v) ((v) << 18)
#define FW_CDEV_ISO_SY(v) ((v) << 20)
#define FW_CDEV_ISO_HEADER_LENGTH(v) ((v) << 24)
+/**
+ * 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
+ * payload length (16 lowermost bits)
+ * @header: Header and payload
+ *
+ * &struct fw_cdev_iso_packet is used to describe isochronous packet queues.
+ *
+ * Use the FW_CDEV_ISO_ macros to fill in @control. The sy and tag fields are
+ * specified by IEEE 1394a and IEC 61883.
+ *
+ * FIXME - finish this documentation
+ */
struct fw_cdev_iso_packet {
__u32 control;
__u32 header[0];
};
+/**
+ * struct fw_cdev_queue_iso - Queue isochronous packets for I/O
+ * @packets: Userspace pointer to packet data
+ * @data: Pointer into mmap()'ed payload buffer
+ * @size: Size of packet data in bytes
+ * @handle: Isochronous context handle
+ *
+ * Queue a number of isochronous packets for reception or transmission.
+ * This ioctl takes a pointer to an array of &fw_cdev_iso_packet structs,
+ * which describe how to transmit from or receive into a contiguous region
+ * of a mmap()'ed payload buffer. As part of the packet descriptors,
+ * a series of headers can be supplied, which will be prepended to the
+ * payload during DMA.
+ *
+ * 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.
+ */
struct fw_cdev_queue_iso {
__u64 packets;
__u64 data;
@@ -217,6 +427,23 @@
__u32 handle;
};
+#define FW_CDEV_ISO_CONTEXT_MATCH_TAG0 1
+#define FW_CDEV_ISO_CONTEXT_MATCH_TAG1 2
+#define FW_CDEV_ISO_CONTEXT_MATCH_TAG2 4
+#define FW_CDEV_ISO_CONTEXT_MATCH_TAG3 8
+#define FW_CDEV_ISO_CONTEXT_MATCH_ALL_TAGS 15
+
+/**
+ * struct fw_cdev_start_iso - Start an isochronous transmission or reception
+ * @cycle: Cycle in which to start I/O. If @cycle is greater than or
+ * equal to 0, the I/O will start on that cycle.
+ * @sync: Determines the value to wait for for receive packets that have
+ * the %FW_CDEV_ISO_SYNC bit set
+ * @tags: Tag filter bit mask. Only valid for isochronous reception.
+ * Determines the tag values for which packets will be accepted.
+ * Use FW_CDEV_ISO_CONTEXT_MATCH_ macros to set @tags.
+ * @handle: Isochronous context handle within which to transmit or receive
+ */
struct fw_cdev_start_iso {
__s32 cycle;
__u32 sync;
@@ -224,6 +451,10 @@
__u32 handle;
};
+/**
+ * struct fw_cdev_stop_iso - Stop an isochronous transmission or reception
+ * @handle: Handle of isochronous context to stop
+ */
struct fw_cdev_stop_iso {
__u32 handle;
};