USB: gadget: add USB Audio Gadget driver

Funtions added:
 - setup all the USB audio class device descriptors
 - handle class specific setup request
 - receive data from USB host by ISO transfer
 - play audio data by ALSA sound card
 - open and setup playback PCM interface
 - set default playback PCM parameters
 - provide playback functions for USB audio driver
 - provide PCM parameters set/get functions

Test on:
 - Host: Ubuntu 8.10, kernel 2.6.27
 - Gadget: EZKIT-BF548 with ASoC AD1980 codec

Todo:
 - add real Mute control code
 - add real Volume control code
 - maybe find another way to replace dynamic buffer handling
   with static buffer allocation
 - test on Windows system
 - provide control interface to handle mute/volume control
 - provide capture interface in the future
 - test on BF527, other USB device controler and other audio codec

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 319 insertions, 0 deletions

diff --git a/drivers/usb/gadget/u_audio.c b/drivers/usb/gadget/u_audio.c
new file mode 100644
index 0000000..0f3d22f
--- /dev/null
+++ b/drivers/usb/gadget/u_audio.c
@@ -0,0 +1,319 @@
+/*
+ * u_audio.c -- ALSA audio utilities for Gadget stack
+ *
+ * Copyright (C) 2008 Bryan Wu <cooloney@kernel.org>
+ * Copyright (C) 2008 Analog Devices, Inc
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/kernel.h>
+#include <linux/utsname.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/ctype.h>
+#include <linux/random.h>
+#include <linux/syscalls.h>
+
+#include "u_audio.h"
+
+/*
+ * This component encapsulates the ALSA devices for USB audio gadget
+ */
+
+#define FILE_PCM_PLAYBACK	"/dev/snd/pcmC0D0p"
+#define FILE_PCM_CAPTURE	"/dev/snd/pcmC0D0c"
+#define FILE_CONTROL		"/dev/snd/controlC0"
+
+static char *fn_play = FILE_PCM_PLAYBACK;
+module_param(fn_play, charp, S_IRUGO);
+MODULE_PARM_DESC(fn_play, "Playback PCM device file name");
+
+static char *fn_cap = FILE_PCM_CAPTURE;
+module_param(fn_cap, charp, S_IRUGO);
+MODULE_PARM_DESC(fn_cap, "Capture PCM device file name");
+
+static char *fn_cntl = FILE_CONTROL;
+module_param(fn_cntl, charp, S_IRUGO);
+MODULE_PARM_DESC(fn_cntl, "Control device file name");
+
+/*-------------------------------------------------------------------------*/
+
+/**
+ * Some ALSA internal helper functions
+ */
+static int snd_interval_refine_set(struct snd_interval *i, unsigned int val)
+{
+	struct snd_interval t;
+	t.empty = 0;
+	t.min = t.max = val;
+	t.openmin = t.openmax = 0;
+	t.integer = 1;
+	return snd_interval_refine(i, &t);
+}
+
+static int _snd_pcm_hw_param_set(struct snd_pcm_hw_params *params,
+				 snd_pcm_hw_param_t var, unsigned int val,
+				 int dir)
+{
+	int changed;
+	if (hw_is_mask(var)) {
+		struct snd_mask *m = hw_param_mask(params, var);
+		if (val == 0 && dir < 0) {
+			changed = -EINVAL;
+			snd_mask_none(m);
+		} else {
+			if (dir > 0)
+				val++;
+			else if (dir < 0)
+				val--;
+			changed = snd_mask_refine_set(
+					hw_param_mask(params, var), val);
+		}
+	} else if (hw_is_interval(var)) {
+		struct snd_interval *i = hw_param_interval(params, var);
+		if (val == 0 && dir < 0) {
+			changed = -EINVAL;
+			snd_interval_none(i);
+		} else if (dir == 0)
+			changed = snd_interval_refine_set(i, val);
+		else {
+			struct snd_interval t;
+			t.openmin = 1;
+			t.openmax = 1;
+			t.empty = 0;
+			t.integer = 0;
+			if (dir < 0) {
+				t.min = val - 1;
+				t.max = val;
+			} else {
+				t.min = val;
+				t.max = val+1;
+			}
+			changed = snd_interval_refine(i, &t);
+		}
+	} else
+		return -EINVAL;
+	if (changed) {
+		params->cmask |= 1 << var;
+		params->rmask |= 1 << var;
+	}
+	return changed;
+}
+/*-------------------------------------------------------------------------*/
+
+/**
+ * Set default hardware params
+ */
+static int playback_default_hw_params(struct gaudio_snd_dev *snd)
+{
+	struct snd_pcm_substream *substream = snd->substream;
+	struct snd_pcm_hw_params *params;
+	snd_pcm_sframes_t result;
+
+       /*
+	* SNDRV_PCM_ACCESS_RW_INTERLEAVED,
+	* SNDRV_PCM_FORMAT_S16_LE
+	* CHANNELS: 2
+	* RATE: 48000
+	*/
+	snd->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
+	snd->format = SNDRV_PCM_FORMAT_S16_LE;
+	snd->channels = 2;
+	snd->rate = 48000;
+
+	params = kzalloc(sizeof(*params), GFP_KERNEL);
+	if (!params)
+		return -ENOMEM;
+
+	_snd_pcm_hw_params_any(params);
+	_snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_ACCESS,
+			snd->access, 0);
+	_snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_FORMAT,
+			snd->format, 0);
+	_snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_CHANNELS,
+			snd->channels, 0);
+	_snd_pcm_hw_param_set(params, SNDRV_PCM_HW_PARAM_RATE,
+			snd->rate, 0);
+
+	snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_DROP, NULL);
+	snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_HW_PARAMS, params);
+
+	result = snd_pcm_kernel_ioctl(substream, SNDRV_PCM_IOCTL_PREPARE, NULL);
+	if (result < 0) {
+		ERROR(snd->card,
+			"Preparing sound card failed: %d\n", (int)result);
+		kfree(params);
+		return result;
+	}
+
+	/* Store the hardware parameters */
+	snd->access = params_access(params);
+	snd->format = params_format(params);
+	snd->channels = params_channels(params);
+	snd->rate = params_rate(params);
+
+	kfree(params);
+
+	INFO(snd->card,
+		"Hardware params: access %x, format %x, channels %d, rate %d\n",
+		snd->access, snd->format, snd->channels, snd->rate);
+
+	return 0;
+}
+
+/**
+ * Playback audio buffer data by ALSA PCM device
+ */
+static size_t u_audio_playback(struct gaudio *card, void *buf, size_t count)
+{
+	struct gaudio_snd_dev	*snd = &card->playback;
+	struct snd_pcm_substream *substream = snd->substream;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	mm_segment_t old_fs;
+	ssize_t result;
+	snd_pcm_sframes_t frames;
+
+try_again:
+	if (runtime->status->state == SNDRV_PCM_STATE_XRUN ||
+		runtime->status->state == SNDRV_PCM_STATE_SUSPENDED) {
+		result = snd_pcm_kernel_ioctl(substream,
+				SNDRV_PCM_IOCTL_PREPARE, NULL);
+		if (result < 0) {
+			ERROR(card, "Preparing sound card failed: %d\n",
+					(int)result);
+			return result;
+		}
+	}
+
+	frames = bytes_to_frames(runtime, count);
+	old_fs = get_fs();
+	set_fs(KERNEL_DS);
+	result = snd_pcm_lib_write(snd->substream, buf, frames);
+	if (result != frames) {
+		ERROR(card, "Playback error: %d\n", (int)result);
+		set_fs(old_fs);
+		goto try_again;
+	}
+	set_fs(old_fs);
+
+	return 0;
+}
+
+static int u_audio_get_playback_channels(struct gaudio *card)
+{
+	return card->playback.channels;
+}
+
+static int u_audio_get_playback_rate(struct gaudio *card)
+{
+	return card->playback.rate;
+}
+
+/**
+ * Open ALSA PCM and control device files
+ * Initial the PCM or control device
+ */
+static int gaudio_open_snd_dev(struct gaudio *card)
+{
+	struct snd_pcm_file *pcm_file;
+	struct gaudio_snd_dev *snd;
+
+	if (!card)
+		return -ENODEV;
+
+	/* Open control device */
+	snd = &card->control;
+	snd->filp = filp_open(fn_cntl, O_RDWR, 0);
+	if (IS_ERR(snd->filp)) {
+		int ret = PTR_ERR(snd->filp);
+		ERROR(card, "unable to open sound control device file: %s\n",
+				fn_cntl);
+		snd->filp = NULL;
+		return ret;
+	}
+	snd->card = card;
+
+	/* Open PCM playback device and setup substream */
+	snd = &card->playback;
+	snd->filp = filp_open(fn_play, O_WRONLY, 0);
+	if (IS_ERR(snd->filp)) {
+		ERROR(card, "No such PCM playback device: %s\n", fn_play);
+		snd->filp = NULL;
+	}
+	pcm_file = snd->filp->private_data;
+	snd->substream = pcm_file->substream;
+	snd->card = card;
+	playback_default_hw_params(snd);
+
+	/* Open PCM capture device and setup substream */
+	snd = &card->capture;
+	snd->filp = filp_open(fn_cap, O_RDONLY, 0);
+	if (IS_ERR(snd->filp)) {
+		ERROR(card, "No such PCM capture device: %s\n", fn_cap);
+		snd->filp = NULL;
+	}
+	pcm_file = snd->filp->private_data;
+	snd->substream = pcm_file->substream;
+	snd->card = card;
+
+	return 0;
+}
+
+/**
+ * Close ALSA PCM and control device files
+ */
+static int gaudio_close_snd_dev(struct gaudio *gau)
+{
+	struct gaudio_snd_dev	*snd;
+
+	/* Close control device */
+	snd = &gau->control;
+	if (!IS_ERR(snd->filp))
+		filp_close(snd->filp, current->files);
+
+	/* Close PCM playback device and setup substream */
+	snd = &gau->playback;
+	if (!IS_ERR(snd->filp))
+		filp_close(snd->filp, current->files);
+
+	/* Close PCM capture device and setup substream */
+	snd = &gau->capture;
+	if (!IS_ERR(snd->filp))
+		filp_close(snd->filp, current->files);
+
+	return 0;
+}
+
+/**
+ * gaudio_setup - setup ALSA interface and preparing for USB transfer
+ *
+ * This sets up PCM, mixer or MIDI ALSA devices fore USB gadget using.
+ *
+ * Returns negative errno, or zero on success
+ */
+int __init gaudio_setup(struct gaudio *card)
+{
+	int	ret;
+
+	ret = gaudio_open_snd_dev(card);
+	if (ret)
+		ERROR(card, "we need at least one control device\n");
+
+	return ret;
+
+}
+
+/**
+ * gaudio_cleanup - remove ALSA device interface
+ *
+ * This is called to free all resources allocated by @gaudio_setup().
+ */
+void gaudio_cleanup(struct gaudio *card)
+{
+	if (card)
+		gaudio_close_snd_dev(card);
+}
+