/* * Line 6 Linux USB driver * * Copyright (C) 2004-2010 Markus Grabner (grabner@icg.tugraz.at) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation, version 2. * */ #include #include #include #include #include #include "driver.h" #include "midi.h" #define line6_rawmidi_substream_midi(substream) \ ((struct snd_line6_midi *)((substream)->rmidi->private_data)) static int send_midi_async(struct usb_line6 *line6, unsigned char *data, int length); /* Pass data received via USB to MIDI. */ void line6_midi_receive(struct usb_line6 *line6, unsigned char *data, int length) { if (line6->line6midi->substream_receive) snd_rawmidi_receive(line6->line6midi->substream_receive, data, length); } /* Read data from MIDI buffer and transmit them via USB. */ static void line6_midi_transmit(struct snd_rawmidi_substream *substream) { struct usb_line6 *line6 = line6_rawmidi_substream_midi(substream)->line6; struct snd_line6_midi *line6midi = line6->line6midi; struct midi_buffer *mb = &line6midi->midibuf_out; unsigned char chunk[LINE6_FALLBACK_MAXPACKETSIZE]; int req, done; for (;;) { req = min(line6_midibuf_bytes_free(mb), line6->max_packet_size); done = snd_rawmidi_transmit_peek(substream, chunk, req); if (done == 0) break; line6_midibuf_write(mb, chunk, done); snd_rawmidi_transmit_ack(substream, done); } for (;;) { done = line6_midibuf_read(mb, chunk, LINE6_FALLBACK_MAXPACKETSIZE); if (done == 0) break; send_midi_async(line6, chunk, done); } } /* Notification of completion of MIDI transmission. */ static void midi_sent(struct urb *urb) { unsigned long flags; int status; int num; struct usb_line6 *line6 = (struct usb_line6 *)urb->context; status = urb->status; kfree(urb->transfer_buffer); usb_free_urb(urb); if (status == -ESHUTDOWN) return; spin_lock_irqsave(&line6->line6midi->lock, flags); num = --line6->line6midi->num_active_send_urbs; if (num == 0) { line6_midi_transmit(line6->line6midi->substream_transmit); num = line6->line6midi->num_active_send_urbs; } if (num == 0) wake_up(&line6->line6midi->send_wait); spin_unlock_irqrestore(&line6->line6midi->lock, flags); } /* Send an asynchronous MIDI message. Assumes that line6->line6midi->lock is held (i.e., this function is serialized). */ static int send_midi_async(struct usb_line6 *line6, unsigned char *data, int length) { struct urb *urb; int retval; unsigned char *transfer_buffer; urb = usb_alloc_urb(0, GFP_ATOMIC); if (urb == NULL) return -ENOMEM; transfer_buffer = kmemdup(data, length, GFP_ATOMIC); if (transfer_buffer == NULL) { usb_free_urb(urb); return -ENOMEM; } usb_fill_int_urb(urb, line6->usbdev, usb_sndbulkpipe(line6->usbdev, line6->properties->ep_ctrl_w), transfer_buffer, length, midi_sent, line6, line6->interval); urb->actual_length = 0; retval = usb_submit_urb(urb, GFP_ATOMIC); if (retval < 0) { dev_err(line6->ifcdev, "usb_submit_urb failed\n"); usb_free_urb(urb); return retval; } ++line6->line6midi->num_active_send_urbs; return 0; } static int line6_midi_output_open(struct snd_rawmidi_substream *substream) { return 0; } static int line6_midi_output_close(struct snd_rawmidi_substream *substream) { return 0; } static void line6_midi_output_trigger(struct snd_rawmidi_substream *substream, int up) { unsigned long flags; struct usb_line6 *line6 = line6_rawmidi_substream_midi(substream)->line6; line6->line6midi->substream_transmit = substream; spin_lock_irqsave(&line6->line6midi->lock, flags); if (line6->line6midi->num_active_send_urbs == 0) line6_midi_transmit(substream); spin_unlock_irqrestore(&line6->line6midi->lock, flags); } static void line6_midi_output_drain(struct snd_rawmidi_substream *substream) { struct usb_line6 *line6 = line6_rawmidi_substream_midi(substream)->line6; struct snd_line6_midi *midi = line6->line6midi; wait_event_interruptible(midi->send_wait, midi->num_active_send_urbs == 0); } static int line6_midi_input_open(struct snd_rawmidi_substream *substream) { return 0; } static int line6_midi_input_close(struct snd_rawmidi_substream *substream) { return 0; } static void line6_midi_input_trigger(struct snd_rawmidi_substream *substream, int up) { struct usb_line6 *line6 = line6_rawmidi_substream_midi(substream)->line6; if (up) line6->line6midi->substream_receive = substream; else line6->line6midi->substream_receive = NULL; } static struct snd_rawmidi_ops line6_midi_output_ops = { .open = line6_midi_output_open, .close = line6_midi_output_close, .trigger = line6_midi_output_trigger, .drain = line6_midi_output_drain, }; static struct snd_rawmidi_ops line6_midi_input_ops = { .open = line6_midi_input_open, .close = line6_midi_input_close, .trigger = line6_midi_input_trigger, }; /* Create a MIDI device */ static int snd_line6_new_midi(struct usb_line6 *line6, struct snd_rawmidi **rmidi_ret) { struct snd_rawmidi *rmidi; int err; err = snd_rawmidi_new(line6->card, "Line 6 MIDI", 0, 1, 1, rmidi_ret); if (err < 0) return err; rmidi = *rmidi_ret; strcpy(rmidi->id, line6->properties->id); strcpy(rmidi->name, line6->properties->name); rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT | SNDRV_RAWMIDI_INFO_INPUT | SNDRV_RAWMIDI_INFO_DUPLEX; snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &line6_midi_output_ops); snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &line6_midi_input_ops); return 0; } /* MIDI device destructor */ static void snd_line6_midi_free(struct snd_rawmidi *rmidi) { struct snd_line6_midi *line6midi = rmidi->private_data; line6_midibuf_destroy(&line6midi->midibuf_in); line6_midibuf_destroy(&line6midi->midibuf_out); kfree(line6midi); } /* Initialize the Line 6 MIDI subsystem. */ int line6_init_midi(struct usb_line6 *line6) { int err; struct snd_rawmidi *rmidi; struct snd_line6_midi *line6midi; if (!(line6->properties->capabilities & LINE6_CAP_CONTROL_MIDI)) { /* skip MIDI initialization and report success */ return 0; } err = snd_line6_new_midi(line6, &rmidi); if (err < 0) return err; line6midi = kzalloc(sizeof(struct snd_line6_midi), GFP_KERNEL); if (!line6midi) return -ENOMEM; rmidi->private_data = line6midi; rmidi->private_free = snd_line6_midi_free; init_waitqueue_head(&line6midi->send_wait); spin_lock_init(&line6midi->lock); line6midi->line6 = line6; err = line6_midibuf_init(&line6midi->midibuf_in, MIDI_BUFFER_SIZE, 0); if (err < 0) return err; err = line6_midibuf_init(&line6midi->midibuf_out, MIDI_BUFFER_SIZE, 1); if (err < 0) return err; line6->line6midi = line6midi; return 0; } EXPORT_SYMBOL_GPL(line6_init_midi); e overflow ends up not touching other bits), and look at the other bits of the result. However, an even simpler model is to just use a regular atomic "and" to clear the lock bit, and then the sign bit in eflags will indicate the resulting state of the unrelated bit #7. So by moving the PageWaiters bit up to bit #7, we can atomically clear the lock bit and test the waiters bit on x86 too. And architectures with LL/SC (which is all the usual RISC suspects), the particular bit doesn't matter, so they are fine with this approach too. This avoids the extra access to the same atomic word, and thus avoids the costly stall at page unlock time. The only downside is that the interface ends up being a bit odd and specialized: clear a bit in a byte, and test the sign bit. Nick doesn't love the resulting name of the new primitive, but I'd rather make the name be descriptive and very clear about the limitation imposed by trying to work across all relevant architectures than make it be some generic thing that doesn't make the odd semantics explicit. So this introduces the new architecture primitive clear_bit_unlock_is_negative_byte(); and adds the trivial implementation for x86. We have a generic non-optimized fallback (that just does a "clear_bit()"+"test_bit(7)" combination) which can be overridden by any architecture that can do better. According to Nick, Power has the same hickup x86 has, for example, but some other architectures may not even care. All these optimizations mean that my page locking stress-test (which is just executing a lot of small short-lived shell scripts: "make test" in the git source tree) no longer makes our page locking look horribly bad. Before all these optimizations, just the unlock_page() costs were just over 3% of all CPU overhead on "make test". After this, it's down to 0.66%, so just a quarter of the cost it used to be. (The difference on NUMA is bigger, but there this micro-optimization is likely less noticeable, since the big issue on NUMA was not the accesses to 'struct page', but the waitqueue accesses that were already removed by Nick's earlier commit). Acked-by: Nick Piggin <npiggin@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Bob Peterson <rpeterso@redhat.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Andrew Lutomirski <luto@kernel.org> Cc: Andreas Gruenbacher <agruenba@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/usb/core')