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 <linux/sched/signal.h>
16
17#include <asm/mipsmtregs.h>
18#include <asm/mips_mt.h>
19#include <asm/processor.h>
20#include <asm/rtlx.h>
21#include <asm/setup.h>
22#include <asm/vpe.h>
23
24static int sp_stopping;
25struct rtlx_info *rtlx;
26struct chan_waitqueues channel_wqs[RTLX_CHANNELS];
27struct vpe_notifications rtlx_notify;
28void (*aprp_hook)(void) = NULL;
29EXPORT_SYMBOL(aprp_hook);
30
31static void __used dump_rtlx(void)
32{
33	int i;
34
35	pr_info("id 0x%lx state %d\n", rtlx->id, rtlx->state);
36
37	for (i = 0; i < RTLX_CHANNELS; i++) {
38		struct rtlx_channel *chan = &rtlx->channel[i];
39
40		pr_info(" rt_state %d lx_state %d buffer_size %d\n",
41			chan->rt_state, chan->lx_state, chan->buffer_size);
42
43		pr_info(" rt_read %d rt_write %d\n",
44			chan->rt_read, chan->rt_write);
45
46		pr_info(" lx_read %d lx_write %d\n",
47			chan->lx_read, chan->lx_write);
48
49		pr_info(" rt_buffer <%s>\n", chan->rt_buffer);
50		pr_info(" lx_buffer <%s>\n", chan->lx_buffer);
51	}
52}
53
54/* call when we have the address of the shared structure from the SP side. */
55static int rtlx_init(struct rtlx_info *rtlxi)
56{
57	if (rtlxi->id != RTLX_ID) {
58		pr_err("no valid RTLX id at 0x%p 0x%lx\n", rtlxi, rtlxi->id);
59		return -ENOEXEC;
60	}
61
62	rtlx = rtlxi;
63
64	return 0;
65}
66
67/* notifications */
68void rtlx_starting(int vpe)
69{
70	int i;
71	sp_stopping = 0;
72
73	/* force a reload of rtlx */
74	rtlx = NULL;
75
76	/* wake up any sleeping rtlx_open's */
77	for (i = 0; i < RTLX_CHANNELS; i++)
78		wake_up_interruptible(&channel_wqs[i].lx_queue);
79}
80
81void rtlx_stopping(int vpe)
82{
83	int i;
84
85	sp_stopping = 1;
86	for (i = 0; i < RTLX_CHANNELS; i++)
87		wake_up_interruptible(&channel_wqs[i].lx_queue);
88}
89
90
91int rtlx_open(int index, int can_sleep)
92{
93	struct rtlx_info **p;
94	struct rtlx_channel *chan;
95	enum rtlx_state state;
96	int ret = 0;
97
98	if (index >= RTLX_CHANNELS) {
99		pr_debug("rtlx_open index out of range\n");
100		return -ENOSYS;
101	}
102
103	if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
104		pr_debug("rtlx_open channel %d already opened\n", index);
105		ret = -EBUSY;
106		goto out_fail;
107	}
108
109	if (rtlx == NULL) {
110		p = vpe_get_shared(aprp_cpu_index());
111		if (p == NULL) {
112			if (can_sleep) {
113				ret = __wait_event_interruptible(
114					channel_wqs[index].lx_queue,
115					(p = vpe_get_shared(aprp_cpu_index())));
116				if (ret)
117					goto out_fail;
118			} else {
119				pr_debug("No SP program loaded, and device opened with O_NONBLOCK\n");
120				ret = -ENOSYS;
121				goto out_fail;
122			}
123		}
124
125		smp_rmb();
126		if (*p == NULL) {
127			if (can_sleep) {
128				DEFINE_WAIT(wait);
129
130				for (;;) {
131					prepare_to_wait(
132						&channel_wqs[index].lx_queue,
133						&wait, TASK_INTERRUPTIBLE);
134					smp_rmb();
135					if (*p != NULL)
136						break;
137					if (!signal_pending(current)) {
138						schedule();
139						continue;
140					}
141					ret = -ERESTARTSYS;
142					goto out_fail;
143				}
144				finish_wait(&channel_wqs[index].lx_queue,
145					    &wait);
146			} else {
147				pr_err(" *vpe_get_shared is NULL. Has an SP program been loaded?\n");
148				ret = -ENOSYS;
149				goto out_fail;
150			}
151		}
152
153		if ((unsigned int)*p < KSEG0) {
154			pr_warn("vpe_get_shared returned an invalid pointer maybe an error code %d\n",
155				(int)*p);
156			ret = -ENOSYS;
157			goto out_fail;
158		}
159
160		ret = rtlx_init(*p);
161		if (ret < 0)
162			goto out_ret;
163	}
164
165	chan = &rtlx->channel[index];
166
167	state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
168	if (state == RTLX_STATE_OPENED) {
169		ret = -EBUSY;
170		goto out_fail;
171	}
172
173out_fail:
174	smp_mb();
175	atomic_dec(&channel_wqs[index].in_open);
176	smp_mb();
177
178out_ret:
179	return ret;
180}
181
182int rtlx_release(int index)
183{
184	if (rtlx == NULL) {
185		pr_err("rtlx_release() with null rtlx\n");
186		return 0;
187	}
188	rtlx->channel[index].lx_state = RTLX_STATE_UNUSED;
189	return 0;
190}
191
192unsigned int rtlx_read_poll(int index, int can_sleep)
193{
194	struct rtlx_channel *chan;
195
196	if (rtlx == NULL)
197		return 0;
198
199	chan = &rtlx->channel[index];
200
201	/* data available to read? */
202	if (chan->lx_read == chan->lx_write) {
203		if (can_sleep) {
204			int ret = __wait_event_interruptible(
205				channel_wqs[index].lx_queue,
206				(chan->lx_read != chan->lx_write) ||
207				sp_stopping);
208			if (ret)
209				return ret;
210
211			if (sp_stopping)
212				return 0;
213		} else
214			return 0;
215	}
216
217	return (chan->lx_write + chan->buffer_size - chan->lx_read)
218	       % chan->buffer_size;
219}
220
221static inline int write_spacefree(int read, int write, int size)
222{
223	if (read == write) {
224		/*
225		 * Never fill the buffer completely, so indexes are always
226		 * equal if empty and only empty, or !equal if data available
227		 */
228		return size - 1;
229	}
230
231	return ((read + size - write) % size) - 1;
232}
233
234unsigned int rtlx_write_poll(int index)
235{
236	struct rtlx_channel *chan = &rtlx->channel[index];
237
238	return write_spacefree(chan->rt_read, chan->rt_write,
239				chan->buffer_size);
240}
241
242ssize_t rtlx_read(int index, void __user *buff, size_t count)
243{
244	size_t lx_write, fl = 0L;
245	struct rtlx_channel *lx;
246	unsigned long failed;
247
248	if (rtlx == NULL)
249		return -ENOSYS;
250
251	lx = &rtlx->channel[index];
252
253	mutex_lock(&channel_wqs[index].mutex);
254	smp_rmb();
255	lx_write = lx->lx_write;
256
257	/* find out how much in total */
258	count = min(count,
259		     (size_t)(lx_write + lx->buffer_size - lx->lx_read)
260		     % lx->buffer_size);
261
262	/* then how much from the read pointer onwards */
263	fl = min(count, (size_t)lx->buffer_size - lx->lx_read);
264
265	failed = copy_to_user(buff, lx->lx_buffer + lx->lx_read, fl);
266	if (failed)
267		goto out;
268
269	/* and if there is anything left at the beginning of the buffer */
270	if (count - fl)
271		failed = copy_to_user(buff + fl, lx->lx_buffer, count - fl);
272
273out:
274	count -= failed;
275
276	smp_wmb();
277	lx->lx_read = (lx->lx_read + count) % lx->buffer_size;
278	smp_wmb();
279	mutex_unlock(&channel_wqs[index].mutex);
280
281	return count;
282}
283
284ssize_t rtlx_write(int index, const void __user *buffer, size_t count)
285{
286	struct rtlx_channel *rt;
287	unsigned long failed;
288	size_t rt_read;
289	size_t fl;
290
291	if (rtlx == NULL)
292		return -ENOSYS;
293
294	rt = &rtlx->channel[index];
295
296	mutex_lock(&channel_wqs[index].mutex);
297	smp_rmb();
298	rt_read = rt->rt_read;
299
300	/* total number of bytes to copy */
301	count = min_t(size_t, count, write_spacefree(rt_read, rt->rt_write,
302						     rt->buffer_size));
303
304	/* first bit from write pointer to the end of the buffer, or count */
305	fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
306
307	failed = copy_from_user(rt->rt_buffer + rt->rt_write, buffer, fl);
308	if (failed)
309		goto out;
310
311	/* if there's any left copy to the beginning of the buffer */
312	if (count - fl)
313		failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
314
315out:
316	count -= failed;
317
318	smp_wmb();
319	rt->rt_write = (rt->rt_write + count) % rt->buffer_size;
320	smp_wmb();
321	mutex_unlock(&channel_wqs[index].mutex);
322
323	_interrupt_sp();
324
325	return count;
326}
327
328
329static int file_open(struct inode *inode, struct file *filp)
330{
331	return rtlx_open(iminor(inode), (filp->f_flags & O_NONBLOCK) ? 0 : 1);
332}
333
334static int file_release(struct inode *inode, struct file *filp)
335{
336	return rtlx_release(iminor(inode));
337}
338
339static __poll_t file_poll(struct file *file, poll_table *wait)
340{
341	int minor = iminor(file_inode(file));
342	__poll_t mask = 0;
343
344	poll_wait(file, &channel_wqs[minor].rt_queue, wait);
345	poll_wait(file, &channel_wqs[minor].lx_queue, wait);
346
347	if (rtlx == NULL)
348		return 0;
349
350	/* data available to read? */
351	if (rtlx_read_poll(minor, 0))
352		mask |= EPOLLIN | EPOLLRDNORM;
353
354	/* space to write */
355	if (rtlx_write_poll(minor))
356		mask |= EPOLLOUT | EPOLLWRNORM;
357
358	return mask;
359}
360
361static ssize_t file_read(struct file *file, char __user *buffer, size_t count,
362			 loff_t *ppos)
363{
364	int minor = iminor(file_inode(file));
365
366	/* data available? */
367	if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1))
368		return 0;	/* -EAGAIN makes 'cat' whine */
369
370	return rtlx_read(minor, buffer, count);
371}
372
373static ssize_t file_write(struct file *file, const char __user *buffer,
374			  size_t count, loff_t *ppos)
375{
376	int minor = iminor(file_inode(file));
377
378	/* any space left... */
379	if (!rtlx_write_poll(minor)) {
380		int ret;
381
382		if (file->f_flags & O_NONBLOCK)
383			return -EAGAIN;
384
385		ret = __wait_event_interruptible(channel_wqs[minor].rt_queue,
386					   rtlx_write_poll(minor));
387		if (ret)
388			return ret;
389	}
390
391	return rtlx_write(minor, buffer, count);
392}
393
394const struct file_operations rtlx_fops = {
395	.owner =   THIS_MODULE,
396	.open =    file_open,
397	.release = file_release,
398	.write =   file_write,
399	.read =    file_read,
400	.poll =    file_poll,
401	.llseek =  noop_llseek,
402};
403
404module_init(rtlx_module_init);
405module_exit(rtlx_module_exit);
406
407MODULE_DESCRIPTION("MIPS RTLX");
408MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
409MODULE_LICENSE("GPL");
410