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Linux/arch/mips/kernel/smp-bmips.c

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

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