1/*
2 * drivers/misc/goldfish_audio.c
3 *
4 * Copyright (C) 2007 Google, Inc.
5 * Copyright (C) 2012 Intel, Inc.
6 *
7 * This software is licensed under the terms of the GNU General Public
8 * License version 2, as published by the Free Software Foundation, and
9 * may be copied, distributed, and modified under those terms.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 */
17
18#include <linux/module.h>
19#include <linux/miscdevice.h>
20#include <linux/fs.h>
21#include <linux/platform_device.h>
22#include <linux/types.h>
23#include <linux/pci.h>
24#include <linux/interrupt.h>
25#include <linux/io.h>
26#include <linux/sched.h>
27#include <linux/dma-mapping.h>
28#include <linux/uaccess.h>
29#include <linux/goldfish.h>
30
31MODULE_AUTHOR("Google, Inc.");
32MODULE_DESCRIPTION("Android QEMU Audio Driver");
33MODULE_LICENSE("GPL");
34MODULE_VERSION("1.0");
35
36struct goldfish_audio {
37	char __iomem *reg_base;
38	int irq;
39	/* lock protects access to buffer_status and to device registers */
40	spinlock_t lock;
41	wait_queue_head_t wait;
42
43	char *buffer_virt;		/* combined buffer virtual address */
44	unsigned long buffer_phys;      /* combined buffer physical address */
45
46	char *write_buffer1;		/* write buffer 1 virtual address */
47	char *write_buffer2;		/* write buffer 2 virtual address */
48	char *read_buffer;		/* read buffer virtual address */
49	int buffer_status;
50	int read_supported;         /* true if we have audio input support */
51};
52
53/*
54 *  We will allocate two read buffers and two write buffers.
55 *  Having two read buffers facilitate stereo -> mono conversion.
56 *  Having two write buffers facilitate interleaved IO.
57 */
58#define READ_BUFFER_SIZE        16384
59#define WRITE_BUFFER_SIZE       16384
60#define COMBINED_BUFFER_SIZE    ((2 * READ_BUFFER_SIZE) + \
61					(2 * WRITE_BUFFER_SIZE))
62
63#define AUDIO_READ(data, addr)		(readl(data->reg_base + addr))
64#define AUDIO_WRITE(data, addr, x)	(writel(x, data->reg_base + addr))
65#define AUDIO_WRITE64(data, addr, addr2, x)	\
66	(gf_write_dma_addr((x), data->reg_base + addr, data->reg_base+addr2))
67
68/*
69 *  temporary variable used between goldfish_audio_probe() and
70 *  goldfish_audio_open()
71 */
72static struct goldfish_audio *audio_data;
73
74enum {
75	/* audio status register */
76	AUDIO_INT_STATUS	= 0x00,
77	/* set this to enable IRQ */
78	AUDIO_INT_ENABLE	= 0x04,
79	/* set these to specify buffer addresses */
80	AUDIO_SET_WRITE_BUFFER_1 = 0x08,
81	AUDIO_SET_WRITE_BUFFER_2 = 0x0C,
82	/* set number of bytes in buffer to write */
83	AUDIO_WRITE_BUFFER_1  = 0x10,
84	AUDIO_WRITE_BUFFER_2  = 0x14,
85	AUDIO_SET_WRITE_BUFFER_1_HIGH = 0x28,
86	AUDIO_SET_WRITE_BUFFER_2_HIGH = 0x30,
87
88	/* true if audio input is supported */
89	AUDIO_READ_SUPPORTED = 0x18,
90	/* buffer to use for audio input */
91	AUDIO_SET_READ_BUFFER = 0x1C,
92	AUDIO_SET_READ_BUFFER_HIGH = 0x34,
93
94	/* driver writes number of bytes to read */
95	AUDIO_START_READ  = 0x20,
96
97	/* number of bytes available in read buffer */
98	AUDIO_READ_BUFFER_AVAILABLE  = 0x24,
99
100	/* AUDIO_INT_STATUS bits */
101
102	/* this bit set when it is safe to write more bytes to the buffer */
103	AUDIO_INT_WRITE_BUFFER_1_EMPTY	= 1U << 0,
104	AUDIO_INT_WRITE_BUFFER_2_EMPTY	= 1U << 1,
105	AUDIO_INT_READ_BUFFER_FULL      = 1U << 2,
106
107	AUDIO_INT_MASK                  = AUDIO_INT_WRITE_BUFFER_1_EMPTY |
108					  AUDIO_INT_WRITE_BUFFER_2_EMPTY |
109					  AUDIO_INT_READ_BUFFER_FULL,
110};
111
112static atomic_t open_count = ATOMIC_INIT(0);
113
114static ssize_t goldfish_audio_read(struct file *fp, char __user *buf,
115				   size_t count, loff_t *pos)
116{
117	struct goldfish_audio *data = fp->private_data;
118	int length;
119	int result = 0;
120
121	if (!data->read_supported)
122		return -ENODEV;
123
124	while (count > 0) {
125		length = (count > READ_BUFFER_SIZE ? READ_BUFFER_SIZE : count);
126		AUDIO_WRITE(data, AUDIO_START_READ, length);
127
128		wait_event_interruptible(data->wait, data->buffer_status &
129					 AUDIO_INT_READ_BUFFER_FULL);
130
131		length = AUDIO_READ(data, AUDIO_READ_BUFFER_AVAILABLE);
132
133		/* copy data to user space */
134		if (copy_to_user(buf, data->read_buffer, length))
135			return -EFAULT;
136
137		result += length;
138		buf += length;
139		count -= length;
140	}
141	return result;
142}
143
144static ssize_t goldfish_audio_write(struct file *fp, const char __user *buf,
145				    size_t count, loff_t *pos)
146{
147	struct goldfish_audio *data = fp->private_data;
148	unsigned long irq_flags;
149	ssize_t result = 0;
150	char *kbuf;
151
152	while (count > 0) {
153		ssize_t copy = count;
154
155		if (copy > WRITE_BUFFER_SIZE)
156			copy = WRITE_BUFFER_SIZE;
157		wait_event_interruptible(data->wait, data->buffer_status &
158					(AUDIO_INT_WRITE_BUFFER_1_EMPTY |
159					AUDIO_INT_WRITE_BUFFER_2_EMPTY));
160
161		if ((data->buffer_status & AUDIO_INT_WRITE_BUFFER_1_EMPTY) != 0)
162			kbuf = data->write_buffer1;
163		else
164			kbuf = data->write_buffer2;
165
166		/* copy from user space to the appropriate buffer */
167		if (copy_from_user(kbuf, buf, copy)) {
168			result = -EFAULT;
169			break;
170		}
171
172		spin_lock_irqsave(&data->lock, irq_flags);
173		/*
174		 *  clear the buffer empty flag, and signal the emulator
175		 *  to start writing the buffer
176		 */
177		if (kbuf == data->write_buffer1) {
178			data->buffer_status &= ~AUDIO_INT_WRITE_BUFFER_1_EMPTY;
179			AUDIO_WRITE(data, AUDIO_WRITE_BUFFER_1, copy);
180		} else {
181			data->buffer_status &= ~AUDIO_INT_WRITE_BUFFER_2_EMPTY;
182			AUDIO_WRITE(data, AUDIO_WRITE_BUFFER_2, copy);
183		}
184		spin_unlock_irqrestore(&data->lock, irq_flags);
185
186		buf += copy;
187		result += copy;
188		count -= copy;
189	}
190	return result;
191}
192
193static int goldfish_audio_open(struct inode *ip, struct file *fp)
194{
195	if (!audio_data)
196		return -ENODEV;
197
198	if (atomic_inc_return(&open_count) == 1) {
199		fp->private_data = audio_data;
200		audio_data->buffer_status = (AUDIO_INT_WRITE_BUFFER_1_EMPTY |
201					     AUDIO_INT_WRITE_BUFFER_2_EMPTY);
202		AUDIO_WRITE(audio_data, AUDIO_INT_ENABLE, AUDIO_INT_MASK);
203		return 0;
204	}
205
206	atomic_dec(&open_count);
207	return -EBUSY;
208}
209
210static int goldfish_audio_release(struct inode *ip, struct file *fp)
211{
212	atomic_dec(&open_count);
213	/* FIXME: surely this is wrong for the multi-opened case */
214	AUDIO_WRITE(audio_data, AUDIO_INT_ENABLE, 0);
215	return 0;
216}
217
218static long goldfish_audio_ioctl(struct file *fp, unsigned int cmd,
219				 unsigned long arg)
220{
221	/* temporary workaround, until we switch to the ALSA API */
222	if (cmd == 315)
223		return -1;
224
225	return 0;
226}
227
228static irqreturn_t goldfish_audio_interrupt(int irq, void *dev_id)
229{
230	unsigned long irq_flags;
231	struct goldfish_audio	*data = dev_id;
232	u32 status;
233
234	spin_lock_irqsave(&data->lock, irq_flags);
235
236	/* read buffer status flags */
237	status = AUDIO_READ(data, AUDIO_INT_STATUS);
238	status &= AUDIO_INT_MASK;
239	/*
240	 *  if buffers are newly empty, wake up blocked
241	 *  goldfish_audio_write() call
242	 */
243	if (status) {
244		data->buffer_status = status;
245		wake_up(&data->wait);
246	}
247
248	spin_unlock_irqrestore(&data->lock, irq_flags);
249	return status ? IRQ_HANDLED : IRQ_NONE;
250}
251
252/* file operations for /dev/eac */
253static const struct file_operations goldfish_audio_fops = {
254	.owner = THIS_MODULE,
255	.read = goldfish_audio_read,
256	.write = goldfish_audio_write,
257	.open = goldfish_audio_open,
258	.release = goldfish_audio_release,
259	.unlocked_ioctl = goldfish_audio_ioctl,
260};
261
262static struct miscdevice goldfish_audio_device = {
263	.minor = MISC_DYNAMIC_MINOR,
264	.name = "eac",
265	.fops = &goldfish_audio_fops,
266};
267
268static int goldfish_audio_probe(struct platform_device *pdev)
269{
270	int ret;
271	struct resource *r;
272	struct goldfish_audio *data;
273	dma_addr_t buf_addr;
274
275	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
276	if (!data)
277		return -ENOMEM;
278	spin_lock_init(&data->lock);
279	init_waitqueue_head(&data->wait);
280	platform_set_drvdata(pdev, data);
281
282	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
283	if (r == NULL) {
284		dev_err(&pdev->dev, "platform_get_resource failed\n");
285		return -ENODEV;
286	}
287	data->reg_base = devm_ioremap(&pdev->dev, r->start, PAGE_SIZE);
288	if (data->reg_base == NULL)
289		return -ENOMEM;
290
291	data->irq = platform_get_irq(pdev, 0);
292	if (data->irq < 0) {
293		dev_err(&pdev->dev, "platform_get_irq failed\n");
294		return -ENODEV;
295	}
296	data->buffer_virt = dmam_alloc_coherent(&pdev->dev,
297				COMBINED_BUFFER_SIZE, &buf_addr, GFP_KERNEL);
298	if (data->buffer_virt == NULL) {
299		dev_err(&pdev->dev, "allocate buffer failed\n");
300		return -ENOMEM;
301	}
302	data->buffer_phys = buf_addr;
303	data->write_buffer1 = data->buffer_virt;
304	data->write_buffer2 = data->buffer_virt + WRITE_BUFFER_SIZE;
305	data->read_buffer = data->buffer_virt + 2 * WRITE_BUFFER_SIZE;
306
307	ret = devm_request_irq(&pdev->dev, data->irq, goldfish_audio_interrupt,
308			       IRQF_SHARED, pdev->name, data);
309	if (ret) {
310		dev_err(&pdev->dev, "request_irq failed\n");
311		return ret;
312	}
313
314	ret = misc_register(&goldfish_audio_device);
315	if (ret) {
316		dev_err(&pdev->dev,
317			"misc_register returned %d in goldfish_audio_init\n",
318								ret);
319		return ret;
320	}
321
322	AUDIO_WRITE64(data, AUDIO_SET_WRITE_BUFFER_1,
323		      AUDIO_SET_WRITE_BUFFER_1_HIGH, buf_addr);
324	buf_addr += WRITE_BUFFER_SIZE;
325
326	AUDIO_WRITE64(data, AUDIO_SET_WRITE_BUFFER_2,
327		      AUDIO_SET_WRITE_BUFFER_2_HIGH, buf_addr);
328
329	buf_addr += WRITE_BUFFER_SIZE;
330
331	data->read_supported = AUDIO_READ(data, AUDIO_READ_SUPPORTED);
332	if (data->read_supported)
333		AUDIO_WRITE64(data, AUDIO_SET_READ_BUFFER,
334			      AUDIO_SET_READ_BUFFER_HIGH, buf_addr);
335
336	audio_data = data;
337	return 0;
338}
339
340static int goldfish_audio_remove(struct platform_device *pdev)
341{
342	misc_deregister(&goldfish_audio_device);
343	audio_data = NULL;
344	return 0;
345}
346
347static struct platform_driver goldfish_audio_driver = {
348	.probe		= goldfish_audio_probe,
349	.remove		= goldfish_audio_remove,
350	.driver = {
351		.name = "goldfish_audio"
352	}
353};
354
355module_platform_driver(goldfish_audio_driver);
356