goldfish: audio support

(remove change to another file that escaped into the patch set)

From: Mike Lockwood <[e-mail]>

Provide a simple audio channel between the kernel and the emulator that host
sit. Queued for staging right now as this ought to be an ALSA driver not
just a dumb device of its own making.

Signed-off-by: Mike A. Chan <[e-mail]>
[x86 support]
Signed-off-by: Sheng Yang <[e-mail]>
Signed-off-by: Yunhong Jiang <[e-mail]>
Signed-off-by: Xiaohui Xin <[e-mail]>
Signed-off-by: Jun Nakajima <[e-mail]>
Signed-off-by: Bruce Beare <[e-mail]>
[Clean up]
Signed-off-by: Alan Cox <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/Kconfig

···
 
 source "drivers/staging/zcache/Kconfig"
 
+source "drivers/staging/goldfish/Kconfig"
+
 endif # STAGING

drivers/staging/Makefile

···
 obj-$(CONFIG_SB105X)		+= sb105x/
 obj-$(CONFIG_FIREWIRE_SERIAL)	+= fwserial/
 obj-$(CONFIG_ZCACHE)		+= zcache/
+obj-$(CONFIG_GOLDFISH)		+= goldfish/

drivers/staging/goldfish/Kconfig

···
+config GOLDFISH_AUDIO
+	tristate "Goldfish AVD Audio Device"
+	depends on GOLDFISH
+	---help---
+	  Emulated audio channel for the Goldfish Android Virtual Device
+

drivers/staging/goldfish/Makefile

···
+#
+# Makefile for the Goldfish audio driver
+#
+
+obj-$(CONFIG_GOLDFISH_AUDIO) += goldfish_audio.o

drivers/staging/goldfish/README

···
+- Move to using the ALSA framework not faking it
+- Fix the wrong user page DMA (moving to ALSA may fix that too)

drivers/staging/goldfish/goldfish_audio.c

···
+/* drivers/misc/goldfish_audio.c
+ *
+ * Copyright (C) 2007 Google, Inc.
+ * Copyright (C) 2012 Intel, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/sched.h>
+#include <linux/dma-mapping.h>
+#include <linux/uaccess.h>
+
+MODULE_AUTHOR("Google, Inc.");
+MODULE_DESCRIPTION("Android QEMU Audio Driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0");
+
+struct goldfish_audio {
+	char __iomem *reg_base;
+	int irq;
+	spinlock_t lock;
+	wait_queue_head_t wait;
+
+	char __iomem *buffer_virt;      /* combined buffer virtual address */
+	unsigned long buffer_phys;      /* combined buffer physical address */
+
+	char __iomem *write_buffer1;    /* write buffer 1 virtual address */
+	char __iomem *write_buffer2;    /* write buffer 2 virtual address */
+	char __iomem *read_buffer;      /* read buffer virtual address */
+	int buffer_status;
+	int read_supported;         /* true if we have audio input support */
+};
+
+/* We will allocate two read buffers and two write buffers.
+   Having two read buffers facilitate stereo -> mono conversion.
+   Having two write buffers facilitate interleaved IO.
+*/
+#define READ_BUFFER_SIZE        16384
+#define WRITE_BUFFER_SIZE       16384
+#define COMBINED_BUFFER_SIZE    ((2 * READ_BUFFER_SIZE) + \
+					(2 * WRITE_BUFFER_SIZE))
+
+#define AUDIO_READ(data, addr)		(readl(data->reg_base + addr))
+#define AUDIO_WRITE(data, addr, x)	(writel(x, data->reg_base + addr))
+
+/* temporary variable used between goldfish_audio_probe() and
+   goldfish_audio_open() */
+static struct goldfish_audio *audio_data;
+
+enum {
+	/* audio status register */
+	AUDIO_INT_STATUS	= 0x00,
+	/* set this to enable IRQ */
+	AUDIO_INT_ENABLE	= 0x04,
+	/* set these to specify buffer addresses */
+	AUDIO_SET_WRITE_BUFFER_1 = 0x08,
+	AUDIO_SET_WRITE_BUFFER_2 = 0x0C,
+	/* set number of bytes in buffer to write */
+	AUDIO_WRITE_BUFFER_1  = 0x10,
+	AUDIO_WRITE_BUFFER_2  = 0x14,
+
+	/* true if audio input is supported */
+	AUDIO_READ_SUPPORTED = 0x18,
+	/* buffer to use for audio input */
+	AUDIO_SET_READ_BUFFER = 0x1C,
+
+	/* driver writes number of bytes to read */
+	AUDIO_START_READ  = 0x20,
+
+	/* number of bytes available in read buffer */
+	AUDIO_READ_BUFFER_AVAILABLE  = 0x24,
+
+	/* AUDIO_INT_STATUS bits */
+
+	/* this bit set when it is safe to write more bytes to the buffer */
+	AUDIO_INT_WRITE_BUFFER_1_EMPTY	= 1U << 0,
+	AUDIO_INT_WRITE_BUFFER_2_EMPTY	= 1U << 1,
+	AUDIO_INT_READ_BUFFER_FULL      = 1U << 2,
+
+	AUDIO_INT_MASK                  = AUDIO_INT_WRITE_BUFFER_1_EMPTY |
+					  AUDIO_INT_WRITE_BUFFER_2_EMPTY |
+					  AUDIO_INT_READ_BUFFER_FULL,
+};
+
+
+static atomic_t open_count = ATOMIC_INIT(0);
+
+
+static ssize_t goldfish_audio_read(struct file *fp, char __user *buf,
+						size_t count, loff_t *pos)
+{
+	struct goldfish_audio *data = fp->private_data;
+	int length;
+	int result = 0;
+
+	if (!data->read_supported)
+		return -ENODEV;
+
+	while (count > 0) {
+		length = (count > READ_BUFFER_SIZE ? READ_BUFFER_SIZE : count);
+		AUDIO_WRITE(data, AUDIO_START_READ, length);
+
+		wait_event_interruptible(data->wait,
+			(data->buffer_status & AUDIO_INT_READ_BUFFER_FULL));
+
+		length = AUDIO_READ(data,
+						AUDIO_READ_BUFFER_AVAILABLE);
+
+		/* copy data to user space */
+		if (copy_to_user(buf, data->read_buffer, length))
+			return -EFAULT;
+
+		result += length;
+		buf += length;
+		count -= length;
+	}
+	return result;
+}
+
+static ssize_t goldfish_audio_write(struct file *fp, const char __user *buf,
+						 size_t count, loff_t *pos)
+{
+	struct goldfish_audio *data = fp->private_data;
+	unsigned long irq_flags;
+	ssize_t result = 0;
+	char __iomem *kbuf;
+
+	while (count > 0) {
+		ssize_t copy = count;
+		if (copy > WRITE_BUFFER_SIZE)
+			copy = WRITE_BUFFER_SIZE;
+		wait_event_interruptible(data->wait, (data->buffer_status &
+					(AUDIO_INT_WRITE_BUFFER_1_EMPTY |
+					AUDIO_INT_WRITE_BUFFER_2_EMPTY)));
+
+		if ((data->buffer_status & AUDIO_INT_WRITE_BUFFER_1_EMPTY) != 0)
+			kbuf = data->write_buffer1;
+		else
+			kbuf = data->write_buffer2;
+
+		/* copy from user space to the appropriate buffer */
+		if (copy_from_user(kbuf, buf, copy)) {
+			result = -EFAULT;
+			break;
+		}
+
+		spin_lock_irqsave(&data->lock, irq_flags);
+		/* clear the buffer empty flag, and signal the emulator
+		 * to start writing the buffer */
+		if (kbuf == data->write_buffer1) {
+			data->buffer_status &= ~AUDIO_INT_WRITE_BUFFER_1_EMPTY;
+			AUDIO_WRITE(data, AUDIO_WRITE_BUFFER_1, copy);
+		} else {
+			data->buffer_status &= ~AUDIO_INT_WRITE_BUFFER_2_EMPTY;
+			AUDIO_WRITE(data, AUDIO_WRITE_BUFFER_2, copy);
+		}
+		spin_unlock_irqrestore(&data->lock, irq_flags);
+
+		buf += copy;
+		result += copy;
+		count -= copy;
+	}
+	return result;
+}
+
+static int goldfish_audio_open(struct inode *ip, struct file *fp)
+{
+	if (!audio_data)
+		return -ENODEV;
+
+	if (atomic_inc_return(&open_count) == 1) {
+		fp->private_data = audio_data;
+		audio_data->buffer_status = (AUDIO_INT_WRITE_BUFFER_1_EMPTY |
+					     AUDIO_INT_WRITE_BUFFER_2_EMPTY);
+		AUDIO_WRITE(audio_data, AUDIO_INT_ENABLE, AUDIO_INT_MASK);
+		return 0;
+	} else {
+		atomic_dec(&open_count);
+		return -EBUSY;
+	}
+}
+
+static int goldfish_audio_release(struct inode *ip, struct file *fp)
+{
+	atomic_dec(&open_count);
+	/* FIXME: surely this is wrong for the multi-opened case */
+	AUDIO_WRITE(audio_data, AUDIO_INT_ENABLE, 0);
+	return 0;
+}
+
+static long goldfish_audio_ioctl(struct file *fp, unsigned int cmd,
+							unsigned long arg)
+{
+	/* temporary workaround, until we switch to the ALSA API */
+	if (cmd == 315)
+		return -1;
+	else
+		return 0;
+}
+
+static irqreturn_t goldfish_audio_interrupt(int irq, void *dev_id)
+{
+	unsigned long irq_flags;
+	struct goldfish_audio	*data = dev_id;
+	u32 status;
+
+	spin_lock_irqsave(&data->lock, irq_flags);
+
+	/* read buffer status flags */
+	status = AUDIO_READ(data, AUDIO_INT_STATUS);
+	status &= AUDIO_INT_MASK;
+	/* if buffers are newly empty, wake up blocked
+	   goldfish_audio_write() call */
+	if (status) {
+		data->buffer_status = status;
+		wake_up(&data->wait);
+	}
+
+	spin_unlock_irqrestore(&data->lock, irq_flags);
+	return status ? IRQ_HANDLED : IRQ_NONE;
+}
+
+/* file operations for /dev/eac */
+static const struct file_operations goldfish_audio_fops = {
+	.owner = THIS_MODULE,
+	.read = goldfish_audio_read,
+	.write = goldfish_audio_write,
+	.open = goldfish_audio_open,
+	.release = goldfish_audio_release,
+	.unlocked_ioctl = goldfish_audio_ioctl,
+};
+
+static struct miscdevice goldfish_audio_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "eac",
+	.fops = &goldfish_audio_fops,
+};
+
+static int goldfish_audio_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct resource *r;
+	struct goldfish_audio *data;
+	dma_addr_t buf_addr;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (data == NULL) {
+		ret = -ENOMEM;
+		goto err_data_alloc_failed;
+	}
+	spin_lock_init(&data->lock);
+	init_waitqueue_head(&data->wait);
+	platform_set_drvdata(pdev, data);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (r == NULL) {
+		dev_err(&pdev->dev, "platform_get_resource failed\n");
+		ret = -ENODEV;
+		goto err_no_io_base;
+	}
+	data->reg_base = ioremap(r->start, PAGE_SIZE);
+	if (data->reg_base == NULL) {
+		ret = -ENOMEM;
+		goto err_no_io_base;
+	}
+
+	data->irq = platform_get_irq(pdev, 0);
+	if (data->irq < 0) {
+		dev_err(&pdev->dev, "platform_get_irq failed\n");
+		ret = -ENODEV;
+		goto err_no_irq;
+	}
+	data->buffer_virt = dma_alloc_coherent(&pdev->dev,
+				COMBINED_BUFFER_SIZE, &buf_addr, GFP_KERNEL);
+	if (data->buffer_virt == 0) {
+		ret = -ENOMEM;
+		dev_err(&pdev->dev, "allocate buffer failed\n");
+		goto err_alloc_write_buffer_failed;
+	}
+	data->buffer_phys = buf_addr;
+	data->write_buffer1 = data->buffer_virt;
+	data->write_buffer2 = data->buffer_virt + WRITE_BUFFER_SIZE;
+	data->read_buffer = data->buffer_virt + 2 * WRITE_BUFFER_SIZE;
+
+	ret = request_irq(data->irq, goldfish_audio_interrupt,
+					IRQF_SHARED, pdev->name, data);
+	if (ret) {
+		dev_err(&pdev->dev, "request_irq failed\n");
+		goto err_request_irq_failed;
+	}
+
+	ret = misc_register(&goldfish_audio_device);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"misc_register returned %d in goldfish_audio_init\n",
+								ret);
+		goto err_misc_register_failed;
+	}
+
+	AUDIO_WRITE(data, AUDIO_SET_WRITE_BUFFER_1, buf_addr);
+	AUDIO_WRITE(data, AUDIO_SET_WRITE_BUFFER_2,
+						buf_addr + WRITE_BUFFER_SIZE);
+
+	data->read_supported = AUDIO_READ(data, AUDIO_READ_SUPPORTED);
+	if (data->read_supported)
+		AUDIO_WRITE(data, AUDIO_SET_READ_BUFFER,
+					buf_addr + 2 * WRITE_BUFFER_SIZE);
+
+	audio_data = data;
+	return 0;
+
+err_misc_register_failed:
+err_request_irq_failed:
+	dma_free_coherent(&pdev->dev, COMBINED_BUFFER_SIZE,
+					data->buffer_virt, data->buffer_phys);
+err_alloc_write_buffer_failed:
+err_no_irq:
+	iounmap(data->reg_base);
+err_no_io_base:
+	kfree(data);
+err_data_alloc_failed:
+	return ret;
+}
+
+static int goldfish_audio_remove(struct platform_device *pdev)
+{
+	struct goldfish_audio *data = platform_get_drvdata(pdev);
+
+	misc_deregister(&goldfish_audio_device);
+	free_irq(data->irq, data);
+	dma_free_coherent(&pdev->dev, COMBINED_BUFFER_SIZE,
+					data->buffer_virt, data->buffer_phys);
+	iounmap(data->reg_base);
+	kfree(data);
+	audio_data = NULL;
+	return 0;
+}
+
+static struct platform_driver goldfish_audio_driver = {
+	.probe		= goldfish_audio_probe,
+	.remove		= goldfish_audio_remove,
+	.driver = {
+		.name = "goldfish_audio"
+	}
+};
+
+module_platform_driver(goldfish_audio_driver);