xref: /openbmc/linux/arch/mips/kernel/smp-bmips.c (revision ddc141e5)
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/sched/task_stack.h>
15 #include <linux/mm.h>
16 #include <linux/delay.h>
17 #include <linux/smp.h>
18 #include <linux/interrupt.h>
19 #include <linux/spinlock.h>
20 #include <linux/cpu.h>
21 #include <linux/cpumask.h>
22 #include <linux/reboot.h>
23 #include <linux/io.h>
24 #include <linux/compiler.h>
25 #include <linux/linkage.h>
26 #include <linux/bug.h>
27 #include <linux/kernel.h>
28 
29 #include <asm/time.h>
30 #include <asm/pgtable.h>
31 #include <asm/processor.h>
32 #include <asm/bootinfo.h>
33 #include <asm/pmon.h>
34 #include <asm/cacheflush.h>
35 #include <asm/tlbflush.h>
36 #include <asm/mipsregs.h>
37 #include <asm/bmips.h>
38 #include <asm/traps.h>
39 #include <asm/barrier.h>
40 #include <asm/cpu-features.h>
41 
42 static int __maybe_unused max_cpus = 1;
43 
44 /* these may be configured by the platform code */
45 int bmips_smp_enabled = 1;
46 int bmips_cpu_offset;
47 cpumask_t bmips_booted_mask;
48 unsigned long bmips_tp1_irqs = IE_IRQ1;
49 
50 #define RESET_FROM_KSEG0		0x80080800
51 #define RESET_FROM_KSEG1		0xa0080800
52 
53 static void bmips_set_reset_vec(int cpu, u32 val);
54 
55 #ifdef CONFIG_SMP
56 
57 /* initial $sp, $gp - used by arch/mips/kernel/bmips_vec.S */
58 unsigned long bmips_smp_boot_sp;
59 unsigned long bmips_smp_boot_gp;
60 
61 static void bmips43xx_send_ipi_single(int cpu, unsigned int action);
62 static void bmips5000_send_ipi_single(int cpu, unsigned int action);
63 static irqreturn_t bmips43xx_ipi_interrupt(int irq, void *dev_id);
64 static irqreturn_t bmips5000_ipi_interrupt(int irq, void *dev_id);
65 
66 /* SW interrupts 0,1 are used for interprocessor signaling */
67 #define IPI0_IRQ			(MIPS_CPU_IRQ_BASE + 0)
68 #define IPI1_IRQ			(MIPS_CPU_IRQ_BASE + 1)
69 
70 #define CPUNUM(cpu, shift)		(((cpu) + bmips_cpu_offset) << (shift))
71 #define ACTION_CLR_IPI(cpu, ipi)	(0x2000 | CPUNUM(cpu, 9) | ((ipi) << 8))
72 #define ACTION_SET_IPI(cpu, ipi)	(0x3000 | CPUNUM(cpu, 9) | ((ipi) << 8))
73 #define ACTION_BOOT_THREAD(cpu)		(0x08 | CPUNUM(cpu, 0))
74 
75 static void __init bmips_smp_setup(void)
76 {
77 	int i, cpu = 1, boot_cpu = 0;
78 	int cpu_hw_intr;
79 
80 	switch (current_cpu_type()) {
81 	case CPU_BMIPS4350:
82 	case CPU_BMIPS4380:
83 		/* arbitration priority */
84 		clear_c0_brcm_cmt_ctrl(0x30);
85 
86 		/* NBK and weak order flags */
87 		set_c0_brcm_config_0(0x30000);
88 
89 		/* Find out if we are running on TP0 or TP1 */
90 		boot_cpu = !!(read_c0_brcm_cmt_local() & (1 << 31));
91 
92 		/*
93 		 * MIPS interrupts 0,1 (SW INT 0,1) cross over to the other
94 		 * thread
95 		 * MIPS interrupt 2 (HW INT 0) is the CPU0 L1 controller output
96 		 * MIPS interrupt 3 (HW INT 1) is the CPU1 L1 controller output
97 		 */
98 		if (boot_cpu == 0)
99 			cpu_hw_intr = 0x02;
100 		else
101 			cpu_hw_intr = 0x1d;
102 
103 		change_c0_brcm_cmt_intr(0xf8018000,
104 					(cpu_hw_intr << 27) | (0x03 << 15));
105 
106 		/* single core, 2 threads (2 pipelines) */
107 		max_cpus = 2;
108 
109 		break;
110 	case CPU_BMIPS5000:
111 		/* enable raceless SW interrupts */
112 		set_c0_brcm_config(0x03 << 22);
113 
114 		/* route HW interrupt 0 to CPU0, HW interrupt 1 to CPU1 */
115 		change_c0_brcm_mode(0x1f << 27, 0x02 << 27);
116 
117 		/* N cores, 2 threads per core */
118 		max_cpus = (((read_c0_brcm_config() >> 6) & 0x03) + 1) << 1;
119 
120 		/* clear any pending SW interrupts */
121 		for (i = 0; i < max_cpus; i++) {
122 			write_c0_brcm_action(ACTION_CLR_IPI(i, 0));
123 			write_c0_brcm_action(ACTION_CLR_IPI(i, 1));
124 		}
125 
126 		break;
127 	default:
128 		max_cpus = 1;
129 	}
130 
131 	if (!bmips_smp_enabled)
132 		max_cpus = 1;
133 
134 	/* this can be overridden by the BSP */
135 	if (!board_ebase_setup)
136 		board_ebase_setup = &bmips_ebase_setup;
137 
138 	__cpu_number_map[boot_cpu] = 0;
139 	__cpu_logical_map[0] = boot_cpu;
140 
141 	for (i = 0; i < max_cpus; i++) {
142 		if (i != boot_cpu) {
143 			__cpu_number_map[i] = cpu;
144 			__cpu_logical_map[cpu] = i;
145 			cpu++;
146 		}
147 		set_cpu_possible(i, 1);
148 		set_cpu_present(i, 1);
149 	}
150 }
151 
152 /*
153  * IPI IRQ setup - runs on CPU0
154  */
155 static void bmips_prepare_cpus(unsigned int max_cpus)
156 {
157 	irqreturn_t (*bmips_ipi_interrupt)(int irq, void *dev_id);
158 
159 	switch (current_cpu_type()) {
160 	case CPU_BMIPS4350:
161 	case CPU_BMIPS4380:
162 		bmips_ipi_interrupt = bmips43xx_ipi_interrupt;
163 		break;
164 	case CPU_BMIPS5000:
165 		bmips_ipi_interrupt = bmips5000_ipi_interrupt;
166 		break;
167 	default:
168 		return;
169 	}
170 
171 	if (request_irq(IPI0_IRQ, bmips_ipi_interrupt, IRQF_PERCPU,
172 			"smp_ipi0", NULL))
173 		panic("Can't request IPI0 interrupt");
174 	if (request_irq(IPI1_IRQ, bmips_ipi_interrupt, IRQF_PERCPU,
175 			"smp_ipi1", NULL))
176 		panic("Can't request IPI1 interrupt");
177 }
178 
179 /*
180  * Tell the hardware to boot CPUx - runs on CPU0
181  */
182 static int bmips_boot_secondary(int cpu, struct task_struct *idle)
183 {
184 	bmips_smp_boot_sp = __KSTK_TOS(idle);
185 	bmips_smp_boot_gp = (unsigned long)task_thread_info(idle);
186 	mb();
187 
188 	/*
189 	 * Initial boot sequence for secondary CPU:
190 	 *   bmips_reset_nmi_vec @ a000_0000 ->
191 	 *   bmips_smp_entry ->
192 	 *   plat_wired_tlb_setup (cached function call; optional) ->
193 	 *   start_secondary (cached jump)
194 	 *
195 	 * Warm restart sequence:
196 	 *   play_dead WAIT loop ->
197 	 *   bmips_smp_int_vec @ BMIPS_WARM_RESTART_VEC ->
198 	 *   eret to play_dead ->
199 	 *   bmips_secondary_reentry ->
200 	 *   start_secondary
201 	 */
202 
203 	pr_info("SMP: Booting CPU%d...\n", cpu);
204 
205 	if (cpumask_test_cpu(cpu, &bmips_booted_mask)) {
206 		/* kseg1 might not exist if this CPU enabled XKS01 */
207 		bmips_set_reset_vec(cpu, RESET_FROM_KSEG0);
208 
209 		switch (current_cpu_type()) {
210 		case CPU_BMIPS4350:
211 		case CPU_BMIPS4380:
212 			bmips43xx_send_ipi_single(cpu, 0);
213 			break;
214 		case CPU_BMIPS5000:
215 			bmips5000_send_ipi_single(cpu, 0);
216 			break;
217 		}
218 	} else {
219 		bmips_set_reset_vec(cpu, RESET_FROM_KSEG1);
220 
221 		switch (current_cpu_type()) {
222 		case CPU_BMIPS4350:
223 		case CPU_BMIPS4380:
224 			/* Reset slave TP1 if booting from TP0 */
225 			if (cpu_logical_map(cpu) == 1)
226 				set_c0_brcm_cmt_ctrl(0x01);
227 			break;
228 		case CPU_BMIPS5000:
229 			write_c0_brcm_action(ACTION_BOOT_THREAD(cpu));
230 			break;
231 		}
232 		cpumask_set_cpu(cpu, &bmips_booted_mask);
233 	}
234 
235 	return 0;
236 }
237 
238 /*
239  * Early setup - runs on secondary CPU after cache probe
240  */
241 static void bmips_init_secondary(void)
242 {
243 	switch (current_cpu_type()) {
244 	case CPU_BMIPS4350:
245 	case CPU_BMIPS4380:
246 		clear_c0_cause(smp_processor_id() ? C_SW1 : C_SW0);
247 		break;
248 	case CPU_BMIPS5000:
249 		write_c0_brcm_action(ACTION_CLR_IPI(smp_processor_id(), 0));
250 		cpu_set_core(&current_cpu_data, (read_c0_brcm_config() >> 25) & 3);
251 		break;
252 	}
253 }
254 
255 /*
256  * Late setup - runs on secondary CPU before entering the idle loop
257  */
258 static void bmips_smp_finish(void)
259 {
260 	pr_info("SMP: CPU%d is running\n", smp_processor_id());
261 
262 	/* make sure there won't be a timer interrupt for a little while */
263 	write_c0_compare(read_c0_count() + mips_hpt_frequency / HZ);
264 
265 	irq_enable_hazard();
266 	set_c0_status(IE_SW0 | IE_SW1 | bmips_tp1_irqs | IE_IRQ5 | ST0_IE);
267 	irq_enable_hazard();
268 }
269 
270 /*
271  * BMIPS5000 raceless IPIs
272  *
273  * Each CPU has two inbound SW IRQs which are independent of all other CPUs.
274  * IPI0 is used for SMP_RESCHEDULE_YOURSELF
275  * IPI1 is used for SMP_CALL_FUNCTION
276  */
277 
278 static void bmips5000_send_ipi_single(int cpu, unsigned int action)
279 {
280 	write_c0_brcm_action(ACTION_SET_IPI(cpu, action == SMP_CALL_FUNCTION));
281 }
282 
283 static irqreturn_t bmips5000_ipi_interrupt(int irq, void *dev_id)
284 {
285 	int action = irq - IPI0_IRQ;
286 
287 	write_c0_brcm_action(ACTION_CLR_IPI(smp_processor_id(), action));
288 
289 	if (action == 0)
290 		scheduler_ipi();
291 	else
292 		generic_smp_call_function_interrupt();
293 
294 	return IRQ_HANDLED;
295 }
296 
297 static void bmips5000_send_ipi_mask(const struct cpumask *mask,
298 	unsigned int action)
299 {
300 	unsigned int i;
301 
302 	for_each_cpu(i, mask)
303 		bmips5000_send_ipi_single(i, action);
304 }
305 
306 /*
307  * BMIPS43xx racey IPIs
308  *
309  * We use one inbound SW IRQ for each CPU.
310  *
311  * A spinlock must be held in order to keep CPUx from accidentally clearing
312  * an incoming IPI when it writes CP0 CAUSE to raise an IPI on CPUy.  The
313  * same spinlock is used to protect the action masks.
314  */
315 
316 static DEFINE_SPINLOCK(ipi_lock);
317 static DEFINE_PER_CPU(int, ipi_action_mask);
318 
319 static void bmips43xx_send_ipi_single(int cpu, unsigned int action)
320 {
321 	unsigned long flags;
322 
323 	spin_lock_irqsave(&ipi_lock, flags);
324 	set_c0_cause(cpu ? C_SW1 : C_SW0);
325 	per_cpu(ipi_action_mask, cpu) |= action;
326 	irq_enable_hazard();
327 	spin_unlock_irqrestore(&ipi_lock, flags);
328 }
329 
330 static irqreturn_t bmips43xx_ipi_interrupt(int irq, void *dev_id)
331 {
332 	unsigned long flags;
333 	int action, cpu = irq - IPI0_IRQ;
334 
335 	spin_lock_irqsave(&ipi_lock, flags);
336 	action = __this_cpu_read(ipi_action_mask);
337 	per_cpu(ipi_action_mask, cpu) = 0;
338 	clear_c0_cause(cpu ? C_SW1 : C_SW0);
339 	spin_unlock_irqrestore(&ipi_lock, flags);
340 
341 	if (action & SMP_RESCHEDULE_YOURSELF)
342 		scheduler_ipi();
343 	if (action & SMP_CALL_FUNCTION)
344 		generic_smp_call_function_interrupt();
345 
346 	return IRQ_HANDLED;
347 }
348 
349 static void bmips43xx_send_ipi_mask(const struct cpumask *mask,
350 	unsigned int action)
351 {
352 	unsigned int i;
353 
354 	for_each_cpu(i, mask)
355 		bmips43xx_send_ipi_single(i, action);
356 }
357 
358 #ifdef CONFIG_HOTPLUG_CPU
359 
360 static int bmips_cpu_disable(void)
361 {
362 	unsigned int cpu = smp_processor_id();
363 
364 	if (cpu == 0)
365 		return -EBUSY;
366 
367 	pr_info("SMP: CPU%d is offline\n", cpu);
368 
369 	set_cpu_online(cpu, false);
370 	calculate_cpu_foreign_map();
371 	irq_cpu_offline();
372 	clear_c0_status(IE_IRQ5);
373 
374 	local_flush_tlb_all();
375 	local_flush_icache_range(0, ~0);
376 
377 	return 0;
378 }
379 
380 static void bmips_cpu_die(unsigned int cpu)
381 {
382 }
383 
384 void __ref play_dead(void)
385 {
386 	idle_task_exit();
387 
388 	/* flush data cache */
389 	_dma_cache_wback_inv(0, ~0);
390 
391 	/*
392 	 * Wakeup is on SW0 or SW1; disable everything else
393 	 * Use BEV !IV (BMIPS_WARM_RESTART_VEC) to avoid the regular Linux
394 	 * IRQ handlers; this clears ST0_IE and returns immediately.
395 	 */
396 	clear_c0_cause(CAUSEF_IV | C_SW0 | C_SW1);
397 	change_c0_status(
398 		IE_IRQ5 | bmips_tp1_irqs | IE_SW0 | IE_SW1 | ST0_IE | ST0_BEV,
399 		IE_SW0 | IE_SW1 | ST0_IE | ST0_BEV);
400 	irq_disable_hazard();
401 
402 	/*
403 	 * wait for SW interrupt from bmips_boot_secondary(), then jump
404 	 * back to start_secondary()
405 	 */
406 	__asm__ __volatile__(
407 	"	wait\n"
408 	"	j	bmips_secondary_reentry\n"
409 	: : : "memory");
410 }
411 
412 #endif /* CONFIG_HOTPLUG_CPU */
413 
414 const struct plat_smp_ops bmips43xx_smp_ops = {
415 	.smp_setup		= bmips_smp_setup,
416 	.prepare_cpus		= bmips_prepare_cpus,
417 	.boot_secondary		= bmips_boot_secondary,
418 	.smp_finish		= bmips_smp_finish,
419 	.init_secondary		= bmips_init_secondary,
420 	.send_ipi_single	= bmips43xx_send_ipi_single,
421 	.send_ipi_mask		= bmips43xx_send_ipi_mask,
422 #ifdef CONFIG_HOTPLUG_CPU
423 	.cpu_disable		= bmips_cpu_disable,
424 	.cpu_die		= bmips_cpu_die,
425 #endif
426 };
427 
428 const struct plat_smp_ops bmips5000_smp_ops = {
429 	.smp_setup		= bmips_smp_setup,
430 	.prepare_cpus		= bmips_prepare_cpus,
431 	.boot_secondary		= bmips_boot_secondary,
432 	.smp_finish		= bmips_smp_finish,
433 	.init_secondary		= bmips_init_secondary,
434 	.send_ipi_single	= bmips5000_send_ipi_single,
435 	.send_ipi_mask		= bmips5000_send_ipi_mask,
436 #ifdef CONFIG_HOTPLUG_CPU
437 	.cpu_disable		= bmips_cpu_disable,
438 	.cpu_die		= bmips_cpu_die,
439 #endif
440 };
441 
442 #endif /* CONFIG_SMP */
443 
444 /***********************************************************************
445  * BMIPS vector relocation
446  * This is primarily used for SMP boot, but it is applicable to some
447  * UP BMIPS systems as well.
448  ***********************************************************************/
449 
450 static void bmips_wr_vec(unsigned long dst, char *start, char *end)
451 {
452 	memcpy((void *)dst, start, end - start);
453 	dma_cache_wback(dst, end - start);
454 	local_flush_icache_range(dst, dst + (end - start));
455 	instruction_hazard();
456 }
457 
458 static inline void bmips_nmi_handler_setup(void)
459 {
460 	bmips_wr_vec(BMIPS_NMI_RESET_VEC, &bmips_reset_nmi_vec,
461 		&bmips_reset_nmi_vec_end);
462 	bmips_wr_vec(BMIPS_WARM_RESTART_VEC, &bmips_smp_int_vec,
463 		&bmips_smp_int_vec_end);
464 }
465 
466 struct reset_vec_info {
467 	int cpu;
468 	u32 val;
469 };
470 
471 static void bmips_set_reset_vec_remote(void *vinfo)
472 {
473 	struct reset_vec_info *info = vinfo;
474 	int shift = info->cpu & 0x01 ? 16 : 0;
475 	u32 mask = ~(0xffff << shift), val = info->val >> 16;
476 
477 	preempt_disable();
478 	if (smp_processor_id() > 0) {
479 		smp_call_function_single(0, &bmips_set_reset_vec_remote,
480 					 info, 1);
481 	} else {
482 		if (info->cpu & 0x02) {
483 			/* BMIPS5200 "should" use mask/shift, but it's buggy */
484 			bmips_write_zscm_reg(0xa0, (val << 16) | val);
485 			bmips_read_zscm_reg(0xa0);
486 		} else {
487 			write_c0_brcm_bootvec((read_c0_brcm_bootvec() & mask) |
488 					      (val << shift));
489 		}
490 	}
491 	preempt_enable();
492 }
493 
494 static void bmips_set_reset_vec(int cpu, u32 val)
495 {
496 	struct reset_vec_info info;
497 
498 	if (current_cpu_type() == CPU_BMIPS5000) {
499 		/* this needs to run from CPU0 (which is always online) */
500 		info.cpu = cpu;
501 		info.val = val;
502 		bmips_set_reset_vec_remote(&info);
503 	} else {
504 		void __iomem *cbr = BMIPS_GET_CBR();
505 
506 		if (cpu == 0)
507 			__raw_writel(val, cbr + BMIPS_RELO_VECTOR_CONTROL_0);
508 		else {
509 			if (current_cpu_type() != CPU_BMIPS4380)
510 				return;
511 			__raw_writel(val, cbr + BMIPS_RELO_VECTOR_CONTROL_1);
512 		}
513 	}
514 	__sync();
515 	back_to_back_c0_hazard();
516 }
517 
518 void bmips_ebase_setup(void)
519 {
520 	unsigned long new_ebase = ebase;
521 
522 	BUG_ON(ebase != CKSEG0);
523 
524 	switch (current_cpu_type()) {
525 	case CPU_BMIPS4350:
526 		/*
527 		 * BMIPS4350 cannot relocate the normal vectors, but it
528 		 * can relocate the BEV=1 vectors.  So CPU1 starts up at
529 		 * the relocated BEV=1, IV=0 general exception vector @
530 		 * 0xa000_0380.
531 		 *
532 		 * set_uncached_handler() is used here because:
533 		 *  - CPU1 will run this from uncached space
534 		 *  - None of the cacheflush functions are set up yet
535 		 */
536 		set_uncached_handler(BMIPS_WARM_RESTART_VEC - CKSEG0,
537 			&bmips_smp_int_vec, 0x80);
538 		__sync();
539 		return;
540 	case CPU_BMIPS3300:
541 	case CPU_BMIPS4380:
542 		/*
543 		 * 0x8000_0000: reset/NMI (initially in kseg1)
544 		 * 0x8000_0400: normal vectors
545 		 */
546 		new_ebase = 0x80000400;
547 		bmips_set_reset_vec(0, RESET_FROM_KSEG0);
548 		break;
549 	case CPU_BMIPS5000:
550 		/*
551 		 * 0x8000_0000: reset/NMI (initially in kseg1)
552 		 * 0x8000_1000: normal vectors
553 		 */
554 		new_ebase = 0x80001000;
555 		bmips_set_reset_vec(0, RESET_FROM_KSEG0);
556 		write_c0_ebase(new_ebase);
557 		break;
558 	default:
559 		return;
560 	}
561 
562 	board_nmi_handler_setup = &bmips_nmi_handler_setup;
563 	ebase = new_ebase;
564 }
565 
566 asmlinkage void __weak plat_wired_tlb_setup(void)
567 {
568 	/*
569 	 * Called when starting/restarting a secondary CPU.
570 	 * Kernel stacks and other important data might only be accessible
571 	 * once the wired entries are present.
572 	 */
573 }
574 
575 void bmips_cpu_setup(void)
576 {
577 	void __iomem __maybe_unused *cbr = BMIPS_GET_CBR();
578 	u32 __maybe_unused cfg;
579 
580 	switch (current_cpu_type()) {
581 	case CPU_BMIPS3300:
582 		/* Set BIU to async mode */
583 		set_c0_brcm_bus_pll(BIT(22));
584 		__sync();
585 
586 		/* put the BIU back in sync mode */
587 		clear_c0_brcm_bus_pll(BIT(22));
588 
589 		/* clear BHTD to enable branch history table */
590 		clear_c0_brcm_reset(BIT(16));
591 
592 		/* Flush and enable RAC */
593 		cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
594 		__raw_writel(cfg | 0x100, cbr + BMIPS_RAC_CONFIG);
595 		__raw_readl(cbr + BMIPS_RAC_CONFIG);
596 
597 		cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
598 		__raw_writel(cfg | 0xf, cbr + BMIPS_RAC_CONFIG);
599 		__raw_readl(cbr + BMIPS_RAC_CONFIG);
600 
601 		cfg = __raw_readl(cbr + BMIPS_RAC_ADDRESS_RANGE);
602 		__raw_writel(cfg | 0x0fff0000, cbr + BMIPS_RAC_ADDRESS_RANGE);
603 		__raw_readl(cbr + BMIPS_RAC_ADDRESS_RANGE);
604 		break;
605 
606 	case CPU_BMIPS4380:
607 		/* CBG workaround for early BMIPS4380 CPUs */
608 		switch (read_c0_prid()) {
609 		case 0x2a040:
610 		case 0x2a042:
611 		case 0x2a044:
612 		case 0x2a060:
613 			cfg = __raw_readl(cbr + BMIPS_L2_CONFIG);
614 			__raw_writel(cfg & ~0x07000000, cbr + BMIPS_L2_CONFIG);
615 			__raw_readl(cbr + BMIPS_L2_CONFIG);
616 		}
617 
618 		/* clear BHTD to enable branch history table */
619 		clear_c0_brcm_config_0(BIT(21));
620 
621 		/* XI/ROTR enable */
622 		set_c0_brcm_config_0(BIT(23));
623 		set_c0_brcm_cmt_ctrl(BIT(15));
624 		break;
625 
626 	case CPU_BMIPS5000:
627 		/* enable RDHWR, BRDHWR */
628 		set_c0_brcm_config(BIT(17) | BIT(21));
629 
630 		/* Disable JTB */
631 		__asm__ __volatile__(
632 		"	.set	noreorder\n"
633 		"	li	$8, 0x5a455048\n"
634 		"	.word	0x4088b00f\n"	/* mtc0	t0, $22, 15 */
635 		"	.word	0x4008b008\n"	/* mfc0	t0, $22, 8 */
636 		"	li	$9, 0x00008000\n"
637 		"	or	$8, $8, $9\n"
638 		"	.word	0x4088b008\n"	/* mtc0	t0, $22, 8 */
639 		"	sync\n"
640 		"	li	$8, 0x0\n"
641 		"	.word	0x4088b00f\n"	/* mtc0	t0, $22, 15 */
642 		"	.set	reorder\n"
643 		: : : "$8", "$9");
644 
645 		/* XI enable */
646 		set_c0_brcm_config(BIT(27));
647 
648 		/* enable MIPS32R2 ROR instruction for XI TLB handlers */
649 		__asm__ __volatile__(
650 		"	li	$8, 0x5a455048\n"
651 		"	.word	0x4088b00f\n"	/* mtc0 $8, $22, 15 */
652 		"	nop; nop; nop\n"
653 		"	.word	0x4008b008\n"	/* mfc0 $8, $22, 8 */
654 		"	lui	$9, 0x0100\n"
655 		"	or	$8, $9\n"
656 		"	.word	0x4088b008\n"	/* mtc0 $8, $22, 8 */
657 		: : : "$8", "$9");
658 		break;
659 	}
660 }
661