xref: /openbmc/linux/arch/mips/kernel/vpe-mt.c (revision 10a03c36)
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) 2004, 2005 MIPS Technologies, Inc.  All rights reserved.
7  * Copyright (C) 2013 Imagination Technologies Ltd.
8  */
9 #include <linux/kernel.h>
10 #include <linux/device.h>
11 #include <linux/fs.h>
12 #include <linux/slab.h>
13 #include <linux/export.h>
14 
15 #include <asm/mipsregs.h>
16 #include <asm/mipsmtregs.h>
17 #include <asm/mips_mt.h>
18 #include <asm/vpe.h>
19 
20 static int major;
21 
22 /* The number of TCs and VPEs physically available on the core */
23 static int hw_tcs, hw_vpes;
24 
25 /* We are prepared so configure and start the VPE... */
vpe_run(struct vpe * v)26 int vpe_run(struct vpe *v)
27 {
28 	unsigned long flags, val, dmt_flag;
29 	struct vpe_notifications *notifier;
30 	unsigned int vpeflags;
31 	struct tc *t;
32 
33 	/* check we are the Master VPE */
34 	local_irq_save(flags);
35 	val = read_c0_vpeconf0();
36 	if (!(val & VPECONF0_MVP)) {
37 		pr_warn("VPE loader: only Master VPE's are able to config MT\n");
38 		local_irq_restore(flags);
39 
40 		return -1;
41 	}
42 
43 	dmt_flag = dmt();
44 	vpeflags = dvpe();
45 
46 	if (list_empty(&v->tc)) {
47 		evpe(vpeflags);
48 		emt(dmt_flag);
49 		local_irq_restore(flags);
50 
51 		pr_warn("VPE loader: No TC's associated with VPE %d\n",
52 			v->minor);
53 
54 		return -ENOEXEC;
55 	}
56 
57 	t = list_first_entry(&v->tc, struct tc, tc);
58 
59 	/* Put MVPE's into 'configuration state' */
60 	set_c0_mvpcontrol(MVPCONTROL_VPC);
61 
62 	settc(t->index);
63 
64 	/* should check it is halted, and not activated */
65 	if ((read_tc_c0_tcstatus() & TCSTATUS_A) ||
66 	   !(read_tc_c0_tchalt() & TCHALT_H)) {
67 		evpe(vpeflags);
68 		emt(dmt_flag);
69 		local_irq_restore(flags);
70 
71 		pr_warn("VPE loader: TC %d is already active!\n",
72 			t->index);
73 
74 		return -ENOEXEC;
75 	}
76 
77 	/*
78 	 * Write the address we want it to start running from in the TCPC
79 	 * register.
80 	 */
81 	write_tc_c0_tcrestart((unsigned long)v->__start);
82 	write_tc_c0_tccontext((unsigned long)0);
83 
84 	/*
85 	 * Mark the TC as activated, not interrupt exempt and not dynamically
86 	 * allocatable
87 	 */
88 	val = read_tc_c0_tcstatus();
89 	val = (val & ~(TCSTATUS_DA | TCSTATUS_IXMT)) | TCSTATUS_A;
90 	write_tc_c0_tcstatus(val);
91 
92 	write_tc_c0_tchalt(read_tc_c0_tchalt() & ~TCHALT_H);
93 
94 	/*
95 	 * We don't pass the memsize here, so VPE programs need to be
96 	 * compiled with DFLT_STACK_SIZE and DFLT_HEAP_SIZE defined.
97 	 */
98 	mttgpr(7, 0);
99 	mttgpr(6, v->ntcs);
100 
101 	/* set up VPE1 */
102 	/*
103 	 * bind the TC to VPE 1 as late as possible so we only have the final
104 	 * VPE registers to set up, and so an EJTAG probe can trigger on it
105 	 */
106 	write_tc_c0_tcbind((read_tc_c0_tcbind() & ~TCBIND_CURVPE) | 1);
107 
108 	write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~(VPECONF0_VPA));
109 
110 	back_to_back_c0_hazard();
111 
112 	/* Set up the XTC bit in vpeconf0 to point at our tc */
113 	write_vpe_c0_vpeconf0((read_vpe_c0_vpeconf0() & ~(VPECONF0_XTC))
114 			      | (t->index << VPECONF0_XTC_SHIFT));
115 
116 	back_to_back_c0_hazard();
117 
118 	/* enable this VPE */
119 	write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_VPA);
120 
121 	/* clear out any left overs from a previous program */
122 	write_vpe_c0_status(0);
123 	write_vpe_c0_cause(0);
124 
125 	/* take system out of configuration state */
126 	clear_c0_mvpcontrol(MVPCONTROL_VPC);
127 
128 	/*
129 	 * SMVP kernels manage VPE enable independently, but uniprocessor
130 	 * kernels need to turn it on, even if that wasn't the pre-dvpe() state.
131 	 */
132 #ifdef CONFIG_SMP
133 	evpe(vpeflags);
134 #else
135 	evpe(EVPE_ENABLE);
136 #endif
137 	emt(dmt_flag);
138 	local_irq_restore(flags);
139 
140 	list_for_each_entry(notifier, &v->notify, list)
141 		notifier->start(VPE_MODULE_MINOR);
142 
143 	return 0;
144 }
145 
cleanup_tc(struct tc * tc)146 void cleanup_tc(struct tc *tc)
147 {
148 	unsigned long flags;
149 	unsigned int mtflags, vpflags;
150 	int tmp;
151 
152 	local_irq_save(flags);
153 	mtflags = dmt();
154 	vpflags = dvpe();
155 	/* Put MVPE's into 'configuration state' */
156 	set_c0_mvpcontrol(MVPCONTROL_VPC);
157 
158 	settc(tc->index);
159 	tmp = read_tc_c0_tcstatus();
160 
161 	/* mark not allocated and not dynamically allocatable */
162 	tmp &= ~(TCSTATUS_A | TCSTATUS_DA);
163 	tmp |= TCSTATUS_IXMT;	/* interrupt exempt */
164 	write_tc_c0_tcstatus(tmp);
165 
166 	write_tc_c0_tchalt(TCHALT_H);
167 	mips_ihb();
168 
169 	clear_c0_mvpcontrol(MVPCONTROL_VPC);
170 	evpe(vpflags);
171 	emt(mtflags);
172 	local_irq_restore(flags);
173 }
174 
175 /* module wrapper entry points */
176 /* give me a vpe */
vpe_alloc(void)177 void *vpe_alloc(void)
178 {
179 	int i;
180 	struct vpe *v;
181 
182 	/* find a vpe */
183 	for (i = 1; i < MAX_VPES; i++) {
184 		v = get_vpe(i);
185 		if (v != NULL) {
186 			v->state = VPE_STATE_INUSE;
187 			return v;
188 		}
189 	}
190 	return NULL;
191 }
192 EXPORT_SYMBOL(vpe_alloc);
193 
194 /* start running from here */
vpe_start(void * vpe,unsigned long start)195 int vpe_start(void *vpe, unsigned long start)
196 {
197 	struct vpe *v = vpe;
198 
199 	v->__start = start;
200 	return vpe_run(v);
201 }
202 EXPORT_SYMBOL(vpe_start);
203 
204 /* halt it for now */
vpe_stop(void * vpe)205 int vpe_stop(void *vpe)
206 {
207 	struct vpe *v = vpe;
208 	struct tc *t;
209 	unsigned int evpe_flags;
210 
211 	evpe_flags = dvpe();
212 
213 	t = list_entry(v->tc.next, struct tc, tc);
214 	if (t != NULL) {
215 		settc(t->index);
216 		write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA);
217 	}
218 
219 	evpe(evpe_flags);
220 
221 	return 0;
222 }
223 EXPORT_SYMBOL(vpe_stop);
224 
225 /* I've done with it thank you */
vpe_free(void * vpe)226 int vpe_free(void *vpe)
227 {
228 	struct vpe *v = vpe;
229 	struct tc *t;
230 	unsigned int evpe_flags;
231 
232 	t = list_entry(v->tc.next, struct tc, tc);
233 	if (t == NULL)
234 		return -ENOEXEC;
235 
236 	evpe_flags = dvpe();
237 
238 	/* Put MVPE's into 'configuration state' */
239 	set_c0_mvpcontrol(MVPCONTROL_VPC);
240 
241 	settc(t->index);
242 	write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA);
243 
244 	/* halt the TC */
245 	write_tc_c0_tchalt(TCHALT_H);
246 	mips_ihb();
247 
248 	/* mark the TC unallocated */
249 	write_tc_c0_tcstatus(read_tc_c0_tcstatus() & ~TCSTATUS_A);
250 
251 	v->state = VPE_STATE_UNUSED;
252 
253 	clear_c0_mvpcontrol(MVPCONTROL_VPC);
254 	evpe(evpe_flags);
255 
256 	return 0;
257 }
258 EXPORT_SYMBOL(vpe_free);
259 
store_kill(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)260 static ssize_t store_kill(struct device *dev, struct device_attribute *attr,
261 			  const char *buf, size_t len)
262 {
263 	struct vpe *vpe = get_vpe(aprp_cpu_index());
264 	struct vpe_notifications *notifier;
265 
266 	list_for_each_entry(notifier, &vpe->notify, list)
267 		notifier->stop(aprp_cpu_index());
268 
269 	release_progmem(vpe->load_addr);
270 	cleanup_tc(get_tc(aprp_cpu_index()));
271 	vpe_stop(vpe);
272 	vpe_free(vpe);
273 
274 	return len;
275 }
276 static DEVICE_ATTR(kill, S_IWUSR, NULL, store_kill);
277 
ntcs_show(struct device * cd,struct device_attribute * attr,char * buf)278 static ssize_t ntcs_show(struct device *cd, struct device_attribute *attr,
279 			 char *buf)
280 {
281 	struct vpe *vpe = get_vpe(aprp_cpu_index());
282 
283 	return sprintf(buf, "%d\n", vpe->ntcs);
284 }
285 
ntcs_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)286 static ssize_t ntcs_store(struct device *dev, struct device_attribute *attr,
287 			  const char *buf, size_t len)
288 {
289 	struct vpe *vpe = get_vpe(aprp_cpu_index());
290 	unsigned long new;
291 	int ret;
292 
293 	ret = kstrtoul(buf, 0, &new);
294 	if (ret < 0)
295 		return ret;
296 
297 	if (new == 0 || new > (hw_tcs - aprp_cpu_index()))
298 		return -EINVAL;
299 
300 	vpe->ntcs = new;
301 
302 	return len;
303 }
304 static DEVICE_ATTR_RW(ntcs);
305 
306 static struct attribute *vpe_attrs[] = {
307 	&dev_attr_kill.attr,
308 	&dev_attr_ntcs.attr,
309 	NULL,
310 };
311 ATTRIBUTE_GROUPS(vpe);
312 
vpe_device_release(struct device * cd)313 static void vpe_device_release(struct device *cd)
314 {
315 }
316 
317 static struct class vpe_class = {
318 	.name = "vpe",
319 	.dev_release = vpe_device_release,
320 	.dev_groups = vpe_groups,
321 };
322 
323 static struct device vpe_device;
324 
vpe_module_init(void)325 int __init vpe_module_init(void)
326 {
327 	unsigned int mtflags, vpflags;
328 	unsigned long flags, val;
329 	struct vpe *v = NULL;
330 	struct tc *t;
331 	int tc, err;
332 
333 	if (!cpu_has_mipsmt) {
334 		pr_warn("VPE loader: not a MIPS MT capable processor\n");
335 		return -ENODEV;
336 	}
337 
338 	if (vpelimit == 0) {
339 		pr_warn("No VPEs reserved for AP/SP, not initialize VPE loader\n"
340 			"Pass maxvpes=<n> argument as kernel argument\n");
341 
342 		return -ENODEV;
343 	}
344 
345 	if (aprp_cpu_index() == 0) {
346 		pr_warn("No TCs reserved for AP/SP, not initialize VPE loader\n"
347 			"Pass maxtcs=<n> argument as kernel argument\n");
348 
349 		return -ENODEV;
350 	}
351 
352 	major = register_chrdev(0, VPE_MODULE_NAME, &vpe_fops);
353 	if (major < 0) {
354 		pr_warn("VPE loader: unable to register character device\n");
355 		return major;
356 	}
357 
358 	err = class_register(&vpe_class);
359 	if (err) {
360 		pr_err("vpe_class registration failed\n");
361 		goto out_chrdev;
362 	}
363 
364 	device_initialize(&vpe_device);
365 	vpe_device.class	= &vpe_class;
366 	vpe_device.parent	= NULL;
367 	dev_set_name(&vpe_device, "vpe1");
368 	vpe_device.devt = MKDEV(major, VPE_MODULE_MINOR);
369 	err = device_add(&vpe_device);
370 	if (err) {
371 		pr_err("Adding vpe_device failed\n");
372 		goto out_class;
373 	}
374 
375 	local_irq_save(flags);
376 	mtflags = dmt();
377 	vpflags = dvpe();
378 
379 	/* Put MVPE's into 'configuration state' */
380 	set_c0_mvpcontrol(MVPCONTROL_VPC);
381 
382 	val = read_c0_mvpconf0();
383 	hw_tcs = (val & MVPCONF0_PTC) + 1;
384 	hw_vpes = ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
385 
386 	for (tc = aprp_cpu_index(); tc < hw_tcs; tc++) {
387 		/*
388 		 * Must re-enable multithreading temporarily or in case we
389 		 * reschedule send IPIs or similar we might hang.
390 		 */
391 		clear_c0_mvpcontrol(MVPCONTROL_VPC);
392 		evpe(vpflags);
393 		emt(mtflags);
394 		local_irq_restore(flags);
395 		t = alloc_tc(tc);
396 		if (!t) {
397 			err = -ENOMEM;
398 			goto out_dev;
399 		}
400 
401 		local_irq_save(flags);
402 		mtflags = dmt();
403 		vpflags = dvpe();
404 		set_c0_mvpcontrol(MVPCONTROL_VPC);
405 
406 		/* VPE's */
407 		if (tc < hw_tcs) {
408 			settc(tc);
409 
410 			v = alloc_vpe(tc);
411 			if (v == NULL) {
412 				pr_warn("VPE: unable to allocate VPE\n");
413 				goto out_reenable;
414 			}
415 
416 			v->ntcs = hw_tcs - aprp_cpu_index();
417 
418 			/* add the tc to the list of this vpe's tc's. */
419 			list_add(&t->tc, &v->tc);
420 
421 			/* deactivate all but vpe0 */
422 			if (tc >= aprp_cpu_index()) {
423 				unsigned long tmp = read_vpe_c0_vpeconf0();
424 
425 				tmp &= ~VPECONF0_VPA;
426 
427 				/* master VPE */
428 				tmp |= VPECONF0_MVP;
429 				write_vpe_c0_vpeconf0(tmp);
430 			}
431 
432 			/* disable multi-threading with TC's */
433 			write_vpe_c0_vpecontrol(read_vpe_c0_vpecontrol() &
434 						~VPECONTROL_TE);
435 
436 			if (tc >= vpelimit) {
437 				/*
438 				 * Set config to be the same as vpe0,
439 				 * particularly kseg0 coherency alg
440 				 */
441 				write_vpe_c0_config(read_c0_config());
442 			}
443 		}
444 
445 		/* TC's */
446 		t->pvpe = v;	/* set the parent vpe */
447 
448 		if (tc >= aprp_cpu_index()) {
449 			unsigned long tmp;
450 
451 			settc(tc);
452 
453 			/*
454 			 * A TC that is bound to any other VPE gets bound to
455 			 * VPE0, ideally I'd like to make it homeless but it
456 			 * doesn't appear to let me bind a TC to a non-existent
457 			 * VPE. Which is perfectly reasonable.
458 			 *
459 			 * The (un)bound state is visible to an EJTAG probe so
460 			 * may notify GDB...
461 			 */
462 			tmp = read_tc_c0_tcbind();
463 			if (tmp & TCBIND_CURVPE) {
464 				/* tc is bound >vpe0 */
465 				write_tc_c0_tcbind(tmp & ~TCBIND_CURVPE);
466 
467 				t->pvpe = get_vpe(0);	/* set the parent vpe */
468 			}
469 
470 			/* halt the TC */
471 			write_tc_c0_tchalt(TCHALT_H);
472 			mips_ihb();
473 
474 			tmp = read_tc_c0_tcstatus();
475 
476 			/* mark not activated and not dynamically allocatable */
477 			tmp &= ~(TCSTATUS_A | TCSTATUS_DA);
478 			tmp |= TCSTATUS_IXMT;	/* interrupt exempt */
479 			write_tc_c0_tcstatus(tmp);
480 		}
481 	}
482 
483 out_reenable:
484 	/* release config state */
485 	clear_c0_mvpcontrol(MVPCONTROL_VPC);
486 
487 	evpe(vpflags);
488 	emt(mtflags);
489 	local_irq_restore(flags);
490 
491 	return 0;
492 
493 out_dev:
494 	device_del(&vpe_device);
495 
496 out_class:
497 	put_device(&vpe_device);
498 	class_unregister(&vpe_class);
499 
500 out_chrdev:
501 	unregister_chrdev(major, VPE_MODULE_NAME);
502 
503 	return err;
504 }
505 
vpe_module_exit(void)506 void __exit vpe_module_exit(void)
507 {
508 	struct vpe *v, *n;
509 
510 	device_unregister(&vpe_device);
511 	class_unregister(&vpe_class);
512 	unregister_chrdev(major, VPE_MODULE_NAME);
513 
514 	/* No locking needed here */
515 	list_for_each_entry_safe(v, n, &vpecontrol.vpe_list, list) {
516 		if (v->state != VPE_STATE_UNUSED)
517 			release_vpe(v);
518 	}
519 }
520