xref: /linux/arch/mips/kernel/smp-bmips.c (revision 700ea5e0e0dd70420a04e703ff264cc133834cba)
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) 2011 by Kevin Cernekee (cernekee@gmail.com)
7  *
8  * SMP support for BMIPS
9  */
10 
11 #include <linux/init.h>
12 #include <linux/sched.h>
13 #include <linux/sched/hotplug.h>
14 #include <linux/mm.h>
15 #include <linux/delay.h>
16 #include <linux/smp.h>
17 #include <linux/interrupt.h>
18 #include <linux/spinlock.h>
19 #include <linux/cpu.h>
20 #include <linux/cpumask.h>
21 #include <linux/reboot.h>
22 #include <linux/io.h>
23 #include <linux/compiler.h>
24 #include <linux/linkage.h>
25 #include <linux/bug.h>
26 #include <linux/kernel.h>
27 
28 #include <asm/time.h>
29 #include <asm/pgtable.h>
30 #include <asm/processor.h>
31 #include <asm/bootinfo.h>
32 #include <asm/pmon.h>
33 #include <asm/cacheflush.h>
34 #include <asm/tlbflush.h>
35 #include <asm/mipsregs.h>
36 #include <asm/bmips.h>
37 #include <asm/traps.h>
38 #include <asm/barrier.h>
39 #include <asm/cpu-features.h>
40 
41 static int __maybe_unused max_cpus = 1;
42 
43 /* these may be configured by the platform code */
44 int bmips_smp_enabled = 1;
45 int bmips_cpu_offset;
46 cpumask_t bmips_booted_mask;
47 unsigned long bmips_tp1_irqs = IE_IRQ1;
48 
49 #define RESET_FROM_KSEG0		0x80080800
50 #define RESET_FROM_KSEG1		0xa0080800
51 
52 static void bmips_set_reset_vec(int cpu, u32 val);
53 
54 #ifdef CONFIG_SMP
55 
56 /* initial $sp, $gp - used by arch/mips/kernel/bmips_vec.S */
57 unsigned long bmips_smp_boot_sp;
58 unsigned long bmips_smp_boot_gp;
59 
60 static void bmips43xx_send_ipi_single(int cpu, unsigned int action);
61 static void bmips5000_send_ipi_single(int cpu, unsigned int action);
62 static irqreturn_t bmips43xx_ipi_interrupt(int irq, void *dev_id);
63 static irqreturn_t bmips5000_ipi_interrupt(int irq, void *dev_id);
64 
65 /* SW interrupts 0,1 are used for interprocessor signaling */
66 #define IPI0_IRQ			(MIPS_CPU_IRQ_BASE + 0)
67 #define IPI1_IRQ			(MIPS_CPU_IRQ_BASE + 1)
68 
69 #define CPUNUM(cpu, shift)		(((cpu) + bmips_cpu_offset) << (shift))
70 #define ACTION_CLR_IPI(cpu, ipi)	(0x2000 | CPUNUM(cpu, 9) | ((ipi) << 8))
71 #define ACTION_SET_IPI(cpu, ipi)	(0x3000 | CPUNUM(cpu, 9) | ((ipi) << 8))
72 #define ACTION_BOOT_THREAD(cpu)		(0x08 | CPUNUM(cpu, 0))
73 
74 static void __init bmips_smp_setup(void)
75 {
76 	int i, cpu = 1, boot_cpu = 0;
77 	int cpu_hw_intr;
78 
79 	switch (current_cpu_type()) {
80 	case CPU_BMIPS4350:
81 	case CPU_BMIPS4380:
82 		/* arbitration priority */
83 		clear_c0_brcm_cmt_ctrl(0x30);
84 
85 		/* NBK and weak order flags */
86 		set_c0_brcm_config_0(0x30000);
87 
88 		/* Find out if we are running on TP0 or TP1 */
89 		boot_cpu = !!(read_c0_brcm_cmt_local() & (1 << 31));
90 
91 		/*
92 		 * MIPS interrupts 0,1 (SW INT 0,1) cross over to the other
93 		 * thread
94 		 * MIPS interrupt 2 (HW INT 0) is the CPU0 L1 controller output
95 		 * MIPS interrupt 3 (HW INT 1) is the CPU1 L1 controller output
96 		 */
97 		if (boot_cpu == 0)
98 			cpu_hw_intr = 0x02;
99 		else
100 			cpu_hw_intr = 0x1d;
101 
102 		change_c0_brcm_cmt_intr(0xf8018000,
103 					(cpu_hw_intr << 27) | (0x03 << 15));
104 
105 		/* single core, 2 threads (2 pipelines) */
106 		max_cpus = 2;
107 
108 		break;
109 	case CPU_BMIPS5000:
110 		/* enable raceless SW interrupts */
111 		set_c0_brcm_config(0x03 << 22);
112 
113 		/* route HW interrupt 0 to CPU0, HW interrupt 1 to CPU1 */
114 		change_c0_brcm_mode(0x1f << 27, 0x02 << 27);
115 
116 		/* N cores, 2 threads per core */
117 		max_cpus = (((read_c0_brcm_config() >> 6) & 0x03) + 1) << 1;
118 
119 		/* clear any pending SW interrupts */
120 		for (i = 0; i < max_cpus; i++) {
121 			write_c0_brcm_action(ACTION_CLR_IPI(i, 0));
122 			write_c0_brcm_action(ACTION_CLR_IPI(i, 1));
123 		}
124 
125 		break;
126 	default:
127 		max_cpus = 1;
128 	}
129 
130 	if (!bmips_smp_enabled)
131 		max_cpus = 1;
132 
133 	/* this can be overridden by the BSP */
134 	if (!board_ebase_setup)
135 		board_ebase_setup = &bmips_ebase_setup;
136 
137 	__cpu_number_map[boot_cpu] = 0;
138 	__cpu_logical_map[0] = boot_cpu;
139 
140 	for (i = 0; i < max_cpus; i++) {
141 		if (i != boot_cpu) {
142 			__cpu_number_map[i] = cpu;
143 			__cpu_logical_map[cpu] = i;
144 			cpu++;
145 		}
146 		set_cpu_possible(i, 1);
147 		set_cpu_present(i, 1);
148 	}
149 }
150 
151 /*
152  * IPI IRQ setup - runs on CPU0
153  */
154 static void bmips_prepare_cpus(unsigned int max_cpus)
155 {
156 	irqreturn_t (*bmips_ipi_interrupt)(int irq, void *dev_id);
157 
158 	switch (current_cpu_type()) {
159 	case CPU_BMIPS4350:
160 	case CPU_BMIPS4380:
161 		bmips_ipi_interrupt = bmips43xx_ipi_interrupt;
162 		break;
163 	case CPU_BMIPS5000:
164 		bmips_ipi_interrupt = bmips5000_ipi_interrupt;
165 		break;
166 	default:
167 		return;
168 	}
169 
170 	if (request_irq(IPI0_IRQ, bmips_ipi_interrupt, IRQF_PERCPU,
171 			"smp_ipi0", NULL))
172 		panic("Can't request IPI0 interrupt");
173 	if (request_irq(IPI1_IRQ, bmips_ipi_interrupt, IRQF_PERCPU,
174 			"smp_ipi1", NULL))
175 		panic("Can't request IPI1 interrupt");
176 }
177 
178 /*
179  * Tell the hardware to boot CPUx - runs on CPU0
180  */
181 static void bmips_boot_secondary(int cpu, struct task_struct *idle)
182 {
183 	bmips_smp_boot_sp = __KSTK_TOS(idle);
184 	bmips_smp_boot_gp = (unsigned long)task_thread_info(idle);
185 	mb();
186 
187 	/*
188 	 * Initial boot sequence for secondary CPU:
189 	 *   bmips_reset_nmi_vec @ a000_0000 ->
190 	 *   bmips_smp_entry ->
191 	 *   plat_wired_tlb_setup (cached function call; optional) ->
192 	 *   start_secondary (cached jump)
193 	 *
194 	 * Warm restart sequence:
195 	 *   play_dead WAIT loop ->
196 	 *   bmips_smp_int_vec @ BMIPS_WARM_RESTART_VEC ->
197 	 *   eret to play_dead ->
198 	 *   bmips_secondary_reentry ->
199 	 *   start_secondary
200 	 */
201 
202 	pr_info("SMP: Booting CPU%d...\n", cpu);
203 
204 	if (cpumask_test_cpu(cpu, &bmips_booted_mask)) {
205 		/* kseg1 might not exist if this CPU enabled XKS01 */
206 		bmips_set_reset_vec(cpu, RESET_FROM_KSEG0);
207 
208 		switch (current_cpu_type()) {
209 		case CPU_BMIPS4350:
210 		case CPU_BMIPS4380:
211 			bmips43xx_send_ipi_single(cpu, 0);
212 			break;
213 		case CPU_BMIPS5000:
214 			bmips5000_send_ipi_single(cpu, 0);
215 			break;
216 		}
217 	} else {
218 		bmips_set_reset_vec(cpu, RESET_FROM_KSEG1);
219 
220 		switch (current_cpu_type()) {
221 		case CPU_BMIPS4350:
222 		case CPU_BMIPS4380:
223 			/* Reset slave TP1 if booting from TP0 */
224 			if (cpu_logical_map(cpu) == 1)
225 				set_c0_brcm_cmt_ctrl(0x01);
226 			break;
227 		case CPU_BMIPS5000:
228 			write_c0_brcm_action(ACTION_BOOT_THREAD(cpu));
229 			break;
230 		}
231 		cpumask_set_cpu(cpu, &bmips_booted_mask);
232 	}
233 }
234 
235 /*
236  * Early setup - runs on secondary CPU after cache probe
237  */
238 static void bmips_init_secondary(void)
239 {
240 	switch (current_cpu_type()) {
241 	case CPU_BMIPS4350:
242 	case CPU_BMIPS4380:
243 		clear_c0_cause(smp_processor_id() ? C_SW1 : C_SW0);
244 		break;
245 	case CPU_BMIPS5000:
246 		write_c0_brcm_action(ACTION_CLR_IPI(smp_processor_id(), 0));
247 		current_cpu_data.core = (read_c0_brcm_config() >> 25) & 3;
248 		break;
249 	}
250 }
251 
252 /*
253  * Late setup - runs on secondary CPU before entering the idle loop
254  */
255 static void bmips_smp_finish(void)
256 {
257 	pr_info("SMP: CPU%d is running\n", smp_processor_id());
258 
259 	/* make sure there won't be a timer interrupt for a little while */
260 	write_c0_compare(read_c0_count() + mips_hpt_frequency / HZ);
261 
262 	irq_enable_hazard();
263 	set_c0_status(IE_SW0 | IE_SW1 | bmips_tp1_irqs | IE_IRQ5 | ST0_IE);
264 	irq_enable_hazard();
265 }
266 
267 /*
268  * BMIPS5000 raceless IPIs
269  *
270  * Each CPU has two inbound SW IRQs which are independent of all other CPUs.
271  * IPI0 is used for SMP_RESCHEDULE_YOURSELF
272  * IPI1 is used for SMP_CALL_FUNCTION
273  */
274 
275 static void bmips5000_send_ipi_single(int cpu, unsigned int action)
276 {
277 	write_c0_brcm_action(ACTION_SET_IPI(cpu, action == SMP_CALL_FUNCTION));
278 }
279 
280 static irqreturn_t bmips5000_ipi_interrupt(int irq, void *dev_id)
281 {
282 	int action = irq - IPI0_IRQ;
283 
284 	write_c0_brcm_action(ACTION_CLR_IPI(smp_processor_id(), action));
285 
286 	if (action == 0)
287 		scheduler_ipi();
288 	else
289 		generic_smp_call_function_interrupt();
290 
291 	return IRQ_HANDLED;
292 }
293 
294 static void bmips5000_send_ipi_mask(const struct cpumask *mask,
295 	unsigned int action)
296 {
297 	unsigned int i;
298 
299 	for_each_cpu(i, mask)
300 		bmips5000_send_ipi_single(i, action);
301 }
302 
303 /*
304  * BMIPS43xx racey IPIs
305  *
306  * We use one inbound SW IRQ for each CPU.
307  *
308  * A spinlock must be held in order to keep CPUx from accidentally clearing
309  * an incoming IPI when it writes CP0 CAUSE to raise an IPI on CPUy.  The
310  * same spinlock is used to protect the action masks.
311  */
312 
313 static DEFINE_SPINLOCK(ipi_lock);
314 static DEFINE_PER_CPU(int, ipi_action_mask);
315 
316 static void bmips43xx_send_ipi_single(int cpu, unsigned int action)
317 {
318 	unsigned long flags;
319 
320 	spin_lock_irqsave(&ipi_lock, flags);
321 	set_c0_cause(cpu ? C_SW1 : C_SW0);
322 	per_cpu(ipi_action_mask, cpu) |= action;
323 	irq_enable_hazard();
324 	spin_unlock_irqrestore(&ipi_lock, flags);
325 }
326 
327 static irqreturn_t bmips43xx_ipi_interrupt(int irq, void *dev_id)
328 {
329 	unsigned long flags;
330 	int action, cpu = irq - IPI0_IRQ;
331 
332 	spin_lock_irqsave(&ipi_lock, flags);
333 	action = __this_cpu_read(ipi_action_mask);
334 	per_cpu(ipi_action_mask, cpu) = 0;
335 	clear_c0_cause(cpu ? C_SW1 : C_SW0);
336 	spin_unlock_irqrestore(&ipi_lock, flags);
337 
338 	if (action & SMP_RESCHEDULE_YOURSELF)
339 		scheduler_ipi();
340 	if (action & SMP_CALL_FUNCTION)
341 		generic_smp_call_function_interrupt();
342 
343 	return IRQ_HANDLED;
344 }
345 
346 static void bmips43xx_send_ipi_mask(const struct cpumask *mask,
347 	unsigned int action)
348 {
349 	unsigned int i;
350 
351 	for_each_cpu(i, mask)
352 		bmips43xx_send_ipi_single(i, action);
353 }
354 
355 #ifdef CONFIG_HOTPLUG_CPU
356 
357 static int bmips_cpu_disable(void)
358 {
359 	unsigned int cpu = smp_processor_id();
360 
361 	if (cpu == 0)
362 		return -EBUSY;
363 
364 	pr_info("SMP: CPU%d is offline\n", cpu);
365 
366 	set_cpu_online(cpu, false);
367 	calculate_cpu_foreign_map();
368 	irq_cpu_offline();
369 	clear_c0_status(IE_IRQ5);
370 
371 	local_flush_tlb_all();
372 	local_flush_icache_range(0, ~0);
373 
374 	return 0;
375 }
376 
377 static void bmips_cpu_die(unsigned int cpu)
378 {
379 }
380 
381 void __ref play_dead(void)
382 {
383 	idle_task_exit();
384 
385 	/* flush data cache */
386 	_dma_cache_wback_inv(0, ~0);
387 
388 	/*
389 	 * Wakeup is on SW0 or SW1; disable everything else
390 	 * Use BEV !IV (BMIPS_WARM_RESTART_VEC) to avoid the regular Linux
391 	 * IRQ handlers; this clears ST0_IE and returns immediately.
392 	 */
393 	clear_c0_cause(CAUSEF_IV | C_SW0 | C_SW1);
394 	change_c0_status(
395 		IE_IRQ5 | bmips_tp1_irqs | IE_SW0 | IE_SW1 | ST0_IE | ST0_BEV,
396 		IE_SW0 | IE_SW1 | ST0_IE | ST0_BEV);
397 	irq_disable_hazard();
398 
399 	/*
400 	 * wait for SW interrupt from bmips_boot_secondary(), then jump
401 	 * back to start_secondary()
402 	 */
403 	__asm__ __volatile__(
404 	"	wait\n"
405 	"	j	bmips_secondary_reentry\n"
406 	: : : "memory");
407 }
408 
409 #endif /* CONFIG_HOTPLUG_CPU */
410 
411 struct plat_smp_ops bmips43xx_smp_ops = {
412 	.smp_setup		= bmips_smp_setup,
413 	.prepare_cpus		= bmips_prepare_cpus,
414 	.boot_secondary		= bmips_boot_secondary,
415 	.smp_finish		= bmips_smp_finish,
416 	.init_secondary		= bmips_init_secondary,
417 	.send_ipi_single	= bmips43xx_send_ipi_single,
418 	.send_ipi_mask		= bmips43xx_send_ipi_mask,
419 #ifdef CONFIG_HOTPLUG_CPU
420 	.cpu_disable		= bmips_cpu_disable,
421 	.cpu_die		= bmips_cpu_die,
422 #endif
423 };
424 
425 struct plat_smp_ops bmips5000_smp_ops = {
426 	.smp_setup		= bmips_smp_setup,
427 	.prepare_cpus		= bmips_prepare_cpus,
428 	.boot_secondary		= bmips_boot_secondary,
429 	.smp_finish		= bmips_smp_finish,
430 	.init_secondary		= bmips_init_secondary,
431 	.send_ipi_single	= bmips5000_send_ipi_single,
432 	.send_ipi_mask		= bmips5000_send_ipi_mask,
433 #ifdef CONFIG_HOTPLUG_CPU
434 	.cpu_disable		= bmips_cpu_disable,
435 	.cpu_die		= bmips_cpu_die,
436 #endif
437 };
438 
439 #endif /* CONFIG_SMP */
440 
441 /***********************************************************************
442  * BMIPS vector relocation
443  * This is primarily used for SMP boot, but it is applicable to some
444  * UP BMIPS systems as well.
445  ***********************************************************************/
446 
447 static void bmips_wr_vec(unsigned long dst, char *start, char *end)
448 {
449 	memcpy((void *)dst, start, end - start);
450 	dma_cache_wback(dst, end - start);
451 	local_flush_icache_range(dst, dst + (end - start));
452 	instruction_hazard();
453 }
454 
455 static inline void bmips_nmi_handler_setup(void)
456 {
457 	bmips_wr_vec(BMIPS_NMI_RESET_VEC, &bmips_reset_nmi_vec,
458 		&bmips_reset_nmi_vec_end);
459 	bmips_wr_vec(BMIPS_WARM_RESTART_VEC, &bmips_smp_int_vec,
460 		&bmips_smp_int_vec_end);
461 }
462 
463 struct reset_vec_info {
464 	int cpu;
465 	u32 val;
466 };
467 
468 static void bmips_set_reset_vec_remote(void *vinfo)
469 {
470 	struct reset_vec_info *info = vinfo;
471 	int shift = info->cpu & 0x01 ? 16 : 0;
472 	u32 mask = ~(0xffff << shift), val = info->val >> 16;
473 
474 	preempt_disable();
475 	if (smp_processor_id() > 0) {
476 		smp_call_function_single(0, &bmips_set_reset_vec_remote,
477 					 info, 1);
478 	} else {
479 		if (info->cpu & 0x02) {
480 			/* BMIPS5200 "should" use mask/shift, but it's buggy */
481 			bmips_write_zscm_reg(0xa0, (val << 16) | val);
482 			bmips_read_zscm_reg(0xa0);
483 		} else {
484 			write_c0_brcm_bootvec((read_c0_brcm_bootvec() & mask) |
485 					      (val << shift));
486 		}
487 	}
488 	preempt_enable();
489 }
490 
491 static void bmips_set_reset_vec(int cpu, u32 val)
492 {
493 	struct reset_vec_info info;
494 
495 	if (current_cpu_type() == CPU_BMIPS5000) {
496 		/* this needs to run from CPU0 (which is always online) */
497 		info.cpu = cpu;
498 		info.val = val;
499 		bmips_set_reset_vec_remote(&info);
500 	} else {
501 		void __iomem *cbr = BMIPS_GET_CBR();
502 
503 		if (cpu == 0)
504 			__raw_writel(val, cbr + BMIPS_RELO_VECTOR_CONTROL_0);
505 		else {
506 			if (current_cpu_type() != CPU_BMIPS4380)
507 				return;
508 			__raw_writel(val, cbr + BMIPS_RELO_VECTOR_CONTROL_1);
509 		}
510 	}
511 	__sync();
512 	back_to_back_c0_hazard();
513 }
514 
515 void bmips_ebase_setup(void)
516 {
517 	unsigned long new_ebase = ebase;
518 
519 	BUG_ON(ebase != CKSEG0);
520 
521 	switch (current_cpu_type()) {
522 	case CPU_BMIPS4350:
523 		/*
524 		 * BMIPS4350 cannot relocate the normal vectors, but it
525 		 * can relocate the BEV=1 vectors.  So CPU1 starts up at
526 		 * the relocated BEV=1, IV=0 general exception vector @
527 		 * 0xa000_0380.
528 		 *
529 		 * set_uncached_handler() is used here because:
530 		 *  - CPU1 will run this from uncached space
531 		 *  - None of the cacheflush functions are set up yet
532 		 */
533 		set_uncached_handler(BMIPS_WARM_RESTART_VEC - CKSEG0,
534 			&bmips_smp_int_vec, 0x80);
535 		__sync();
536 		return;
537 	case CPU_BMIPS3300:
538 	case CPU_BMIPS4380:
539 		/*
540 		 * 0x8000_0000: reset/NMI (initially in kseg1)
541 		 * 0x8000_0400: normal vectors
542 		 */
543 		new_ebase = 0x80000400;
544 		bmips_set_reset_vec(0, RESET_FROM_KSEG0);
545 		break;
546 	case CPU_BMIPS5000:
547 		/*
548 		 * 0x8000_0000: reset/NMI (initially in kseg1)
549 		 * 0x8000_1000: normal vectors
550 		 */
551 		new_ebase = 0x80001000;
552 		bmips_set_reset_vec(0, RESET_FROM_KSEG0);
553 		write_c0_ebase(new_ebase);
554 		break;
555 	default:
556 		return;
557 	}
558 
559 	board_nmi_handler_setup = &bmips_nmi_handler_setup;
560 	ebase = new_ebase;
561 }
562 
563 asmlinkage void __weak plat_wired_tlb_setup(void)
564 {
565 	/*
566 	 * Called when starting/restarting a secondary CPU.
567 	 * Kernel stacks and other important data might only be accessible
568 	 * once the wired entries are present.
569 	 */
570 }
571 
572 void __init bmips_cpu_setup(void)
573 {
574 	void __iomem __maybe_unused *cbr = BMIPS_GET_CBR();
575 	u32 __maybe_unused cfg;
576 
577 	switch (current_cpu_type()) {
578 	case CPU_BMIPS3300:
579 		/* Set BIU to async mode */
580 		set_c0_brcm_bus_pll(BIT(22));
581 		__sync();
582 
583 		/* put the BIU back in sync mode */
584 		clear_c0_brcm_bus_pll(BIT(22));
585 
586 		/* clear BHTD to enable branch history table */
587 		clear_c0_brcm_reset(BIT(16));
588 
589 		/* Flush and enable RAC */
590 		cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
591 		__raw_writel(cfg | 0x100, BMIPS_RAC_CONFIG);
592 		__raw_readl(cbr + BMIPS_RAC_CONFIG);
593 
594 		cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
595 		__raw_writel(cfg | 0xf, BMIPS_RAC_CONFIG);
596 		__raw_readl(cbr + BMIPS_RAC_CONFIG);
597 
598 		cfg = __raw_readl(cbr + BMIPS_RAC_ADDRESS_RANGE);
599 		__raw_writel(cfg | 0x0fff0000, cbr + BMIPS_RAC_ADDRESS_RANGE);
600 		__raw_readl(cbr + BMIPS_RAC_ADDRESS_RANGE);
601 		break;
602 
603 	case CPU_BMIPS4380:
604 		/* CBG workaround for early BMIPS4380 CPUs */
605 		switch (read_c0_prid()) {
606 		case 0x2a040:
607 		case 0x2a042:
608 		case 0x2a044:
609 		case 0x2a060:
610 			cfg = __raw_readl(cbr + BMIPS_L2_CONFIG);
611 			__raw_writel(cfg & ~0x07000000, cbr + BMIPS_L2_CONFIG);
612 			__raw_readl(cbr + BMIPS_L2_CONFIG);
613 		}
614 
615 		/* clear BHTD to enable branch history table */
616 		clear_c0_brcm_config_0(BIT(21));
617 
618 		/* XI/ROTR enable */
619 		set_c0_brcm_config_0(BIT(23));
620 		set_c0_brcm_cmt_ctrl(BIT(15));
621 		break;
622 
623 	case CPU_BMIPS5000:
624 		/* enable RDHWR, BRDHWR */
625 		set_c0_brcm_config(BIT(17) | BIT(21));
626 
627 		/* Disable JTB */
628 		__asm__ __volatile__(
629 		"	.set	noreorder\n"
630 		"	li	$8, 0x5a455048\n"
631 		"	.word	0x4088b00f\n"	/* mtc0	t0, $22, 15 */
632 		"	.word	0x4008b008\n"	/* mfc0	t0, $22, 8 */
633 		"	li	$9, 0x00008000\n"
634 		"	or	$8, $8, $9\n"
635 		"	.word	0x4088b008\n"	/* mtc0	t0, $22, 8 */
636 		"	sync\n"
637 		"	li	$8, 0x0\n"
638 		"	.word	0x4088b00f\n"	/* mtc0	t0, $22, 15 */
639 		"	.set	reorder\n"
640 		: : : "$8", "$9");
641 
642 		/* XI enable */
643 		set_c0_brcm_config(BIT(27));
644 
645 		/* enable MIPS32R2 ROR instruction for XI TLB handlers */
646 		__asm__ __volatile__(
647 		"	li	$8, 0x5a455048\n"
648 		"	.word	0x4088b00f\n"	/* mtc0 $8, $22, 15 */
649 		"	nop; nop; nop\n"
650 		"	.word	0x4008b008\n"	/* mfc0 $8, $22, 8 */
651 		"	lui	$9, 0x0100\n"
652 		"	or	$8, $9\n"
653 		"	.word	0x4088b008\n"	/* mtc0 $8, $22, 8 */
654 		: : : "$8", "$9");
655 		break;
656 	}
657 }
658