Some models receive MIDI messages via IEEE 1394 asynchronous transactions. In this case, MIDI messages are transferred in fixed-length payload. It's nice that firewire-lib module has common helper functions.
This commit implements this idea. Each driver adds 'struct snd_fw_async_midi_port' in its instance structure. In probing, it should call snd_fw_async_midi_port_init() to initialize the structure with some parameters such as target address, the length of payload in a transaction and a pointer for callback function to fill the payload buffer. At 'struct snd_rawmidi_ops.trigger()' callback, it should call 'snd_fw_async_midi_port_run()' to start transactions. Each driver should ensure that the lifetime of MIDI substream continues till calling 'snd_fw_async_midi_port_finish()'.
The helper functions support retries to transferring MIDI messages when transmission errors occur. When transactions are successful, the helper functions call 'snd_rawmidi_transmit_ack()' internally to consume MIDI bytes in the buffer. Therefore, Each driver is expected to use 'snd_rawmidi_transmit_peek()' to tell the number of bytes to transfer in return value of 'fill' callback.
Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp --- sound/firewire/lib.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++ sound/firewire/lib.h | 50 +++++++++++++++++++++++++ 2 files changed, 153 insertions(+)
diff --git a/sound/firewire/lib.c b/sound/firewire/lib.c index 7409edb..03ada3f 100644 --- a/sound/firewire/lib.c +++ b/sound/firewire/lib.c @@ -9,6 +9,7 @@ #include <linux/device.h> #include <linux/firewire.h> #include <linux/module.h> +#include <linux/slab.h> #include "lib.h"
#define ERROR_RETRY_DELAY_MS 20 @@ -66,6 +67,108 @@ int snd_fw_transaction(struct fw_unit *unit, int tcode, } EXPORT_SYMBOL(snd_fw_transaction);
+static void async_midi_port_callback(struct fw_card *card, int rcode, + void *data, size_t length, + void *callback_data) +{ + struct snd_fw_async_midi_port *port = callback_data; + struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); + + if (rcode == RCODE_COMPLETE && substream != NULL) + snd_rawmidi_transmit_ack(substream, port->consume_bytes); +} + +static void midi_port_work(struct work_struct *work) +{ + struct snd_fw_async_midi_port *port = + container_of(work, struct snd_fw_async_midi_port, work); + struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream); + int generation; + int type; + + /* Nothing to do. */ + if (substream == NULL || snd_rawmidi_transmit_empty(substream)) + return; + + /* + * Fill the buffer. The callee must use snd_rawmidi_transmit_peek(). + * Later, snd_rawmidi_transmit_ack() is called. + */ + memset(port->buf, 0, port->len); + port->consume_bytes = port->fill(substream, port->buf); + if (port->consume_bytes <= 0) { + /* Do it in next chance, immediately. */ + if (port->consume_bytes == 0) + schedule_work(&port->work); + return; + } + + /* Calculate type of transaction. */ + if (port->len == 4) + type = TCODE_WRITE_QUADLET_REQUEST; + else + type = TCODE_WRITE_BLOCK_REQUEST; + + /* Start this transaction. */ + /* + * In Linux FireWire core, when generation is updated with memory + * barrier, node id has already been updated. In this module, After + * this smp_rmb(), load/store instructions to memory are completed. + * Thus, both of generation and node id are available with recent + * values. This is a light-serialization solution to handle bus reset + * events on IEEE 1394 bus. + */ + generation = port->parent->generation; + smp_rmb(); + + fw_send_request(port->parent->card, &port->transaction, type, + port->parent->node_id, generation, + port->parent->max_speed, port->addr, + port->buf, port->len, async_midi_port_callback, + port); +} + +/** + * snd_fw_async_midi_port_init - initialize asynchronous MIDI port structure + * @port: the asynchronous MIDI port to initialize + * @unit: the target of the asynchronous transaction + * @addr: the address to which transactions are transferred + * @len: the length of transaction + * @fill: the callback function to fill given buffer, and returns the + * number of consumed bytes for MIDI message. + * + */ +int snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port, + struct fw_unit *unit, u64 addr, unsigned int len, + snd_fw_async_midi_port_fill fill) +{ + port->len = DIV_ROUND_UP(len, 4) * 4; + port->buf = kzalloc(port->len, GFP_KERNEL); + if (port->buf == NULL) + return -ENOMEM; + + port->parent = fw_parent_device(unit); + port->addr = addr; + port->fill = fill; + + INIT_WORK(&port->work, midi_port_work); + + return 0; +} +EXPORT_SYMBOL(snd_fw_async_midi_port_init); + +/** + * snd_fw_async_midi_port_destroy - free asynchronous MIDI port structure + * @port: the asynchronous MIDI port structure + */ +void snd_fw_async_midi_port_destroy(struct snd_fw_async_midi_port *port) +{ + snd_fw_async_midi_port_finish(port); + cancel_work_sync(&port->work); + kfree(port->buf); +} +EXPORT_SYMBOL(snd_fw_async_midi_port_destroy); + MODULE_DESCRIPTION("FireWire audio helper functions"); MODULE_AUTHOR("Clemens Ladisch clemens@ladisch.de"); MODULE_LICENSE("GPL v2"); diff --git a/sound/firewire/lib.h b/sound/firewire/lib.h index 02cfabc..37a7fe4 100644 --- a/sound/firewire/lib.h +++ b/sound/firewire/lib.h @@ -3,6 +3,8 @@
#include <linux/firewire-constants.h> #include <linux/types.h> +#include <linux/sched.h> +#include <sound/rawmidi.h>
struct fw_unit;
@@ -20,4 +22,52 @@ static inline bool rcode_is_permanent_error(int rcode) return rcode == RCODE_TYPE_ERROR || rcode == RCODE_ADDRESS_ERROR; }
+struct snd_fw_async_midi_port; +typedef int (*snd_fw_async_midi_port_fill)( + struct snd_rawmidi_substream *substream, + u8 *buf); + +struct snd_fw_async_midi_port { + struct fw_device *parent; + struct work_struct work; + + u64 addr; + struct fw_transaction transaction; + + u8 *buf; + unsigned int len; + + struct snd_rawmidi_substream *substream; + snd_fw_async_midi_port_fill fill; + unsigned int consume_bytes; +}; + +int snd_fw_async_midi_port_init(struct snd_fw_async_midi_port *port, + struct fw_unit *unit, u64 addr, unsigned int len, + snd_fw_async_midi_port_fill fill); +void snd_fw_async_midi_port_destroy(struct snd_fw_async_midi_port *port); + +/** + * snd_fw_async_midi_port_run - run transactions for the async MIDI port + * @port: the asynchronous MIDI port + * @substream: the MIDI substream + */ +static inline void +snd_fw_async_midi_port_run(struct snd_fw_async_midi_port *port, + struct snd_rawmidi_substream *substream) +{ + port->substream = substream; + schedule_work(&port->work); +} + +/** + * snd_fw_async_midi_port_finish - finish the asynchronous MIDI port + * @port: the asynchronous MIDI port + */ +static inline void +snd_fw_async_midi_port_finish(struct snd_fw_async_midi_port *port) +{ + port->substream = NULL; +} + #endif