1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 2005 MIPS Technologies, Inc.  All rights reserved.
7 * Copyright (C) 2005, 06 Ralf Baechle (ralf@linux-mips.org)
8 * Copyright (C) 2013 Imagination Technologies Ltd.
9 */
10#include <linux/kernel.h>
11#include <linux/fs.h>
12#include <linux/syscalls.h>
13#include <linux/moduleloader.h>
14#include <linux/atomic.h>
15#include <asm/mipsmtregs.h>
16#include <asm/mips_mt.h>
17#include <asm/processor.h>
18#include <asm/rtlx.h>
19#include <asm/setup.h>
20#include <asm/vpe.h>
21
22static int sp_stopping;
23struct rtlx_info *rtlx;
24struct chan_waitqueues channel_wqs[RTLX_CHANNELS];
25struct vpe_notifications rtlx_notify;
26void (*aprp_hook)(void) = NULL;
27EXPORT_SYMBOL(aprp_hook);
28
29static void __used dump_rtlx(void)
30{
31	int i;
32
33	pr_info("id 0x%lx state %d\n", rtlx->id, rtlx->state);
34
35	for (i = 0; i < RTLX_CHANNELS; i++) {
36		struct rtlx_channel *chan = &rtlx->channel[i];
37
38		pr_info(" rt_state %d lx_state %d buffer_size %d\n",
39			chan->rt_state, chan->lx_state, chan->buffer_size);
40
41		pr_info(" rt_read %d rt_write %d\n",
42			chan->rt_read, chan->rt_write);
43
44		pr_info(" lx_read %d lx_write %d\n",
45			chan->lx_read, chan->lx_write);
46
47		pr_info(" rt_buffer <%s>\n", chan->rt_buffer);
48		pr_info(" lx_buffer <%s>\n", chan->lx_buffer);
49	}
50}
51
52/* call when we have the address of the shared structure from the SP side. */
53static int rtlx_init(struct rtlx_info *rtlxi)
54{
55	if (rtlxi->id != RTLX_ID) {
56		pr_err("no valid RTLX id at 0x%p 0x%lx\n", rtlxi, rtlxi->id);
57		return -ENOEXEC;
58	}
59
60	rtlx = rtlxi;
61
62	return 0;
63}
64
65/* notifications */
66void rtlx_starting(int vpe)
67{
68	int i;
69	sp_stopping = 0;
70
71	/* force a reload of rtlx */
72	rtlx = NULL;
73
74	/* wake up any sleeping rtlx_open's */
75	for (i = 0; i < RTLX_CHANNELS; i++)
76		wake_up_interruptible(&channel_wqs[i].lx_queue);
77}
78
79void rtlx_stopping(int vpe)
80{
81	int i;
82
83	sp_stopping = 1;
84	for (i = 0; i < RTLX_CHANNELS; i++)
85		wake_up_interruptible(&channel_wqs[i].lx_queue);
86}
87
88
89int rtlx_open(int index, int can_sleep)
90{
91	struct rtlx_info **p;
92	struct rtlx_channel *chan;
93	enum rtlx_state state;
94	int ret = 0;
95
96	if (index >= RTLX_CHANNELS) {
97		pr_debug("rtlx_open index out of range\n");
98		return -ENOSYS;
99	}
100
101	if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
102		pr_debug("rtlx_open channel %d already opened\n", index);
103		ret = -EBUSY;
104		goto out_fail;
105	}
106
107	if (rtlx == NULL) {
108		p = vpe_get_shared(aprp_cpu_index());
109		if (p == NULL) {
110			if (can_sleep) {
111				ret = __wait_event_interruptible(
112					channel_wqs[index].lx_queue,
113					(p = vpe_get_shared(aprp_cpu_index())));
114				if (ret)
115					goto out_fail;
116			} else {
117				pr_debug("No SP program loaded, and device opened with O_NONBLOCK\n");
118				ret = -ENOSYS;
119				goto out_fail;
120			}
121		}
122
123		smp_rmb();
124		if (*p == NULL) {
125			if (can_sleep) {
126				DEFINE_WAIT(wait);
127
128				for (;;) {
129					prepare_to_wait(
130						&channel_wqs[index].lx_queue,
131						&wait, TASK_INTERRUPTIBLE);
132					smp_rmb();
133					if (*p != NULL)
134						break;
135					if (!signal_pending(current)) {
136						schedule();
137						continue;
138					}
139					ret = -ERESTARTSYS;
140					goto out_fail;
141				}
142				finish_wait(&channel_wqs[index].lx_queue,
143					    &wait);
144			} else {
145				pr_err(" *vpe_get_shared is NULL. Has an SP program been loaded?\n");
146				ret = -ENOSYS;
147				goto out_fail;
148			}
149		}
150
151		if ((unsigned int)*p < KSEG0) {
152			pr_warn("vpe_get_shared returned an invalid pointer maybe an error code %d\n",
153				(int)*p);
154			ret = -ENOSYS;
155			goto out_fail;
156		}
157
158		ret = rtlx_init(*p);
159		if (ret < 0)
160			goto out_ret;
161	}
162
163	chan = &rtlx->channel[index];
164
165	state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
166	if (state == RTLX_STATE_OPENED) {
167		ret = -EBUSY;
168		goto out_fail;
169	}
170
171out_fail:
172	smp_mb();
173	atomic_dec(&channel_wqs[index].in_open);
174	smp_mb();
175
176out_ret:
177	return ret;
178}
179
180int rtlx_release(int index)
181{
182	if (rtlx == NULL) {
183		pr_err("rtlx_release() with null rtlx\n");
184		return 0;
185	}
186	rtlx->channel[index].lx_state = RTLX_STATE_UNUSED;
187	return 0;
188}
189
190unsigned int rtlx_read_poll(int index, int can_sleep)
191{
192	struct rtlx_channel *chan;
193
194	if (rtlx == NULL)
195		return 0;
196
197	chan = &rtlx->channel[index];
198
199	/* data available to read? */
200	if (chan->lx_read == chan->lx_write) {
201		if (can_sleep) {
202			int ret = __wait_event_interruptible(
203				channel_wqs[index].lx_queue,
204				(chan->lx_read != chan->lx_write) ||
205				sp_stopping);
206			if (ret)
207				return ret;
208
209			if (sp_stopping)
210				return 0;
211		} else
212			return 0;
213	}
214
215	return (chan->lx_write + chan->buffer_size - chan->lx_read)
216	       % chan->buffer_size;
217}
218
219static inline int write_spacefree(int read, int write, int size)
220{
221	if (read == write) {
222		/*
223		 * Never fill the buffer completely, so indexes are always
224		 * equal if empty and only empty, or !equal if data available
225		 */
226		return size - 1;
227	}
228
229	return ((read + size - write) % size) - 1;
230}
231
232unsigned int rtlx_write_poll(int index)
233{
234	struct rtlx_channel *chan = &rtlx->channel[index];
235
236	return write_spacefree(chan->rt_read, chan->rt_write,
237				chan->buffer_size);
238}
239
240ssize_t rtlx_read(int index, void __user *buff, size_t count)
241{
242	size_t lx_write, fl = 0L;
243	struct rtlx_channel *lx;
244	unsigned long failed;
245
246	if (rtlx == NULL)
247		return -ENOSYS;
248
249	lx = &rtlx->channel[index];
250
251	mutex_lock(&channel_wqs[index].mutex);
252	smp_rmb();
253	lx_write = lx->lx_write;
254
255	/* find out how much in total */
256	count = min(count,
257		     (size_t)(lx_write + lx->buffer_size - lx->lx_read)
258		     % lx->buffer_size);
259
260	/* then how much from the read pointer onwards */
261	fl = min(count, (size_t)lx->buffer_size - lx->lx_read);
262
263	failed = copy_to_user(buff, lx->lx_buffer + lx->lx_read, fl);
264	if (failed)
265		goto out;
266
267	/* and if there is anything left at the beginning of the buffer */
268	if (count - fl)
269		failed = copy_to_user(buff + fl, lx->lx_buffer, count - fl);
270
271out:
272	count -= failed;
273
274	smp_wmb();
275	lx->lx_read = (lx->lx_read + count) % lx->buffer_size;
276	smp_wmb();
277	mutex_unlock(&channel_wqs[index].mutex);
278
279	return count;
280}
281
282ssize_t rtlx_write(int index, const void __user *buffer, size_t count)
283{
284	struct rtlx_channel *rt;
285	unsigned long failed;
286	size_t rt_read;
287	size_t fl;
288
289	if (rtlx == NULL)
290		return -ENOSYS;
291
292	rt = &rtlx->channel[index];
293
294	mutex_lock(&channel_wqs[index].mutex);
295	smp_rmb();
296	rt_read = rt->rt_read;
297
298	/* total number of bytes to copy */
299	count = min_t(size_t, count, write_spacefree(rt_read, rt->rt_write,
300						     rt->buffer_size));
301
302	/* first bit from write pointer to the end of the buffer, or count */
303	fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
304
305	failed = copy_from_user(rt->rt_buffer + rt->rt_write, buffer, fl);
306	if (failed)
307		goto out;
308
309	/* if there's any left copy to the beginning of the buffer */
310	if (count - fl)
311		failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
312
313out:
314	count -= failed;
315
316	smp_wmb();
317	rt->rt_write = (rt->rt_write + count) % rt->buffer_size;
318	smp_wmb();
319	mutex_unlock(&channel_wqs[index].mutex);
320
321	_interrupt_sp();
322
323	return count;
324}
325
326
327static int file_open(struct inode *inode, struct file *filp)
328{
329	return rtlx_open(iminor(inode), (filp->f_flags & O_NONBLOCK) ? 0 : 1);
330}
331
332static int file_release(struct inode *inode, struct file *filp)
333{
334	return rtlx_release(iminor(inode));
335}
336
337static unsigned int file_poll(struct file *file, poll_table *wait)
338{
339	int minor = iminor(file_inode(file));
340	unsigned int mask = 0;
341
342	poll_wait(file, &channel_wqs[minor].rt_queue, wait);
343	poll_wait(file, &channel_wqs[minor].lx_queue, wait);
344
345	if (rtlx == NULL)
346		return 0;
347
348	/* data available to read? */
349	if (rtlx_read_poll(minor, 0))
350		mask |= POLLIN | POLLRDNORM;
351
352	/* space to write */
353	if (rtlx_write_poll(minor))
354		mask |= POLLOUT | POLLWRNORM;
355
356	return mask;
357}
358
359static ssize_t file_read(struct file *file, char __user *buffer, size_t count,
360			 loff_t *ppos)
361{
362	int minor = iminor(file_inode(file));
363
364	/* data available? */
365	if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1))
366		return 0;	/* -EAGAIN makes 'cat' whine */
367
368	return rtlx_read(minor, buffer, count);
369}
370
371static ssize_t file_write(struct file *file, const char __user *buffer,
372			  size_t count, loff_t *ppos)
373{
374	int minor = iminor(file_inode(file));
375
376	/* any space left... */
377	if (!rtlx_write_poll(minor)) {
378		int ret;
379
380		if (file->f_flags & O_NONBLOCK)
381			return -EAGAIN;
382
383		ret = __wait_event_interruptible(channel_wqs[minor].rt_queue,
384					   rtlx_write_poll(minor));
385		if (ret)
386			return ret;
387	}
388
389	return rtlx_write(minor, buffer, count);
390}
391
392const struct file_operations rtlx_fops = {
393	.owner =   THIS_MODULE,
394	.open =    file_open,
395	.release = file_release,
396	.write =   file_write,
397	.read =    file_read,
398	.poll =    file_poll,
399	.llseek =  noop_llseek,
400};
401
402module_init(rtlx_module_init);
403module_exit(rtlx_module_exit);
404
405MODULE_DESCRIPTION("MIPS RTLX");
406MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
407MODULE_LICENSE("GPL");
408