xref: /openbmc/linux/arch/arm/mach-mvebu/pmsu.c (revision a325f174)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Power Management Service Unit(PMSU) support for Armada 370/XP platforms.
4  *
5  * Copyright (C) 2012 Marvell
6  *
7  * Yehuda Yitschak <yehuday@marvell.com>
8  * Gregory Clement <gregory.clement@free-electrons.com>
9  * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
10  *
11  * The Armada 370 and Armada XP SOCs have a power management service
12  * unit which is responsible for powering down and waking up CPUs and
13  * other SOC units
14  */
15 
16 #define pr_fmt(fmt) "mvebu-pmsu: " fmt
17 
18 #include <linux/clk.h>
19 #include <linux/cpu_pm.h>
20 #include <linux/delay.h>
21 #include <linux/init.h>
22 #include <linux/io.h>
23 #include <linux/kernel.h>
24 #include <linux/mbus.h>
25 #include <linux/mvebu-pmsu.h>
26 #include <linux/of.h>
27 #include <linux/of_address.h>
28 #include <linux/platform_device.h>
29 #include <linux/resource.h>
30 #include <linux/slab.h>
31 #include <linux/smp.h>
32 #include <asm/cacheflush.h>
33 #include <asm/cp15.h>
34 #include <asm/smp_scu.h>
35 #include <asm/smp_plat.h>
36 #include <asm/suspend.h>
37 #include <asm/tlbflush.h>
38 #include "common.h"
39 #include "pmsu.h"
40 
41 #define PMSU_BASE_OFFSET    0x100
42 #define PMSU_REG_SIZE	    0x1000
43 
44 /* PMSU MP registers */
45 #define PMSU_CONTROL_AND_CONFIG(cpu)	    ((cpu * 0x100) + 0x104)
46 #define PMSU_CONTROL_AND_CONFIG_DFS_REQ		BIT(18)
47 #define PMSU_CONTROL_AND_CONFIG_PWDDN_REQ	BIT(16)
48 #define PMSU_CONTROL_AND_CONFIG_L2_PWDDN	BIT(20)
49 
50 #define PMSU_CPU_POWER_DOWN_CONTROL(cpu)    ((cpu * 0x100) + 0x108)
51 
52 #define PMSU_CPU_POWER_DOWN_DIS_SNP_Q_SKIP	BIT(0)
53 
54 #define PMSU_STATUS_AND_MASK(cpu)	    ((cpu * 0x100) + 0x10c)
55 #define PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT	BIT(16)
56 #define PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT	BIT(17)
57 #define PMSU_STATUS_AND_MASK_IRQ_WAKEUP		BIT(20)
58 #define PMSU_STATUS_AND_MASK_FIQ_WAKEUP		BIT(21)
59 #define PMSU_STATUS_AND_MASK_DBG_WAKEUP		BIT(22)
60 #define PMSU_STATUS_AND_MASK_IRQ_MASK		BIT(24)
61 #define PMSU_STATUS_AND_MASK_FIQ_MASK		BIT(25)
62 
63 #define PMSU_EVENT_STATUS_AND_MASK(cpu)     ((cpu * 0x100) + 0x120)
64 #define PMSU_EVENT_STATUS_AND_MASK_DFS_DONE        BIT(1)
65 #define PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK   BIT(17)
66 
67 #define PMSU_BOOT_ADDR_REDIRECT_OFFSET(cpu) ((cpu * 0x100) + 0x124)
68 
69 /* PMSU fabric registers */
70 #define L2C_NFABRIC_PM_CTL		    0x4
71 #define L2C_NFABRIC_PM_CTL_PWR_DOWN		BIT(20)
72 
73 /* PMSU delay registers */
74 #define PMSU_POWERDOWN_DELAY		    0xF04
75 #define PMSU_POWERDOWN_DELAY_PMU		BIT(1)
76 #define PMSU_POWERDOWN_DELAY_MASK		0xFFFE
77 #define PMSU_DFLT_ARMADA38X_DELAY	        0x64
78 
79 /* CA9 MPcore SoC Control registers */
80 
81 #define MPCORE_RESET_CTL		    0x64
82 #define MPCORE_RESET_CTL_L2			BIT(0)
83 #define MPCORE_RESET_CTL_DEBUG			BIT(16)
84 
85 #define SRAM_PHYS_BASE  0xFFFF0000
86 #define BOOTROM_BASE    0xFFF00000
87 #define BOOTROM_SIZE    0x100000
88 
89 #define ARMADA_370_CRYPT0_ENG_TARGET   0x9
90 #define ARMADA_370_CRYPT0_ENG_ATTR     0x1
91 
92 extern void ll_disable_coherency(void);
93 extern void ll_enable_coherency(void);
94 
95 extern void armada_370_xp_cpu_resume(void);
96 extern void armada_38x_cpu_resume(void);
97 
98 static phys_addr_t pmsu_mp_phys_base;
99 static void __iomem *pmsu_mp_base;
100 
101 static void *mvebu_cpu_resume;
102 
103 static const struct of_device_id of_pmsu_table[] = {
104 	{ .compatible = "marvell,armada-370-pmsu", },
105 	{ .compatible = "marvell,armada-370-xp-pmsu", },
106 	{ .compatible = "marvell,armada-380-pmsu", },
107 	{ /* end of list */ },
108 };
109 
110 void mvebu_pmsu_set_cpu_boot_addr(int hw_cpu, void *boot_addr)
111 {
112 	writel(__pa_symbol(boot_addr), pmsu_mp_base +
113 		PMSU_BOOT_ADDR_REDIRECT_OFFSET(hw_cpu));
114 }
115 
116 extern unsigned char mvebu_boot_wa_start[];
117 extern unsigned char mvebu_boot_wa_end[];
118 
119 /*
120  * This function sets up the boot address workaround needed for SMP
121  * boot on Armada 375 Z1 and cpuidle on Armada 370. It unmaps the
122  * BootROM Mbus window, and instead remaps a crypto SRAM into which a
123  * custom piece of code is copied to replace the problematic BootROM.
124  */
125 int mvebu_setup_boot_addr_wa(unsigned int crypto_eng_target,
126 			     unsigned int crypto_eng_attribute,
127 			     phys_addr_t resume_addr_reg)
128 {
129 	void __iomem *sram_virt_base;
130 	u32 code_len = mvebu_boot_wa_end - mvebu_boot_wa_start;
131 
132 	mvebu_mbus_del_window(BOOTROM_BASE, BOOTROM_SIZE);
133 	mvebu_mbus_add_window_by_id(crypto_eng_target, crypto_eng_attribute,
134 				    SRAM_PHYS_BASE, SZ_64K);
135 
136 	sram_virt_base = ioremap(SRAM_PHYS_BASE, SZ_64K);
137 	if (!sram_virt_base) {
138 		pr_err("Unable to map SRAM to setup the boot address WA\n");
139 		return -ENOMEM;
140 	}
141 
142 	memcpy(sram_virt_base, &mvebu_boot_wa_start, code_len);
143 
144 	/*
145 	 * The last word of the code copied in SRAM must contain the
146 	 * physical base address of the PMSU register. We
147 	 * intentionally store this address in the native endianness
148 	 * of the system.
149 	 */
150 	__raw_writel((unsigned long)resume_addr_reg,
151 		     sram_virt_base + code_len - 4);
152 
153 	iounmap(sram_virt_base);
154 
155 	return 0;
156 }
157 
158 static int __init mvebu_v7_pmsu_init(void)
159 {
160 	struct device_node *np;
161 	struct resource res;
162 	int ret = 0;
163 
164 	np = of_find_matching_node(NULL, of_pmsu_table);
165 	if (!np)
166 		return 0;
167 
168 	pr_info("Initializing Power Management Service Unit\n");
169 
170 	if (of_address_to_resource(np, 0, &res)) {
171 		pr_err("unable to get resource\n");
172 		ret = -ENOENT;
173 		goto out;
174 	}
175 
176 	if (of_device_is_compatible(np, "marvell,armada-370-xp-pmsu")) {
177 		pr_warn(FW_WARN "deprecated pmsu binding\n");
178 		res.start = res.start - PMSU_BASE_OFFSET;
179 		res.end = res.start + PMSU_REG_SIZE - 1;
180 	}
181 
182 	if (!request_mem_region(res.start, resource_size(&res),
183 				np->full_name)) {
184 		pr_err("unable to request region\n");
185 		ret = -EBUSY;
186 		goto out;
187 	}
188 
189 	pmsu_mp_phys_base = res.start;
190 
191 	pmsu_mp_base = ioremap(res.start, resource_size(&res));
192 	if (!pmsu_mp_base) {
193 		pr_err("unable to map registers\n");
194 		release_mem_region(res.start, resource_size(&res));
195 		ret = -ENOMEM;
196 		goto out;
197 	}
198 
199  out:
200 	of_node_put(np);
201 	return ret;
202 }
203 
204 static void mvebu_v7_pmsu_enable_l2_powerdown_onidle(void)
205 {
206 	u32 reg;
207 
208 	if (pmsu_mp_base == NULL)
209 		return;
210 
211 	/* Enable L2 & Fabric powerdown in Deep-Idle mode - Fabric */
212 	reg = readl(pmsu_mp_base + L2C_NFABRIC_PM_CTL);
213 	reg |= L2C_NFABRIC_PM_CTL_PWR_DOWN;
214 	writel(reg, pmsu_mp_base + L2C_NFABRIC_PM_CTL);
215 }
216 
217 enum pmsu_idle_prepare_flags {
218 	PMSU_PREPARE_NORMAL = 0,
219 	PMSU_PREPARE_DEEP_IDLE = BIT(0),
220 	PMSU_PREPARE_SNOOP_DISABLE = BIT(1),
221 };
222 
223 /* No locking is needed because we only access per-CPU registers */
224 static int mvebu_v7_pmsu_idle_prepare(unsigned long flags)
225 {
226 	unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
227 	u32 reg;
228 
229 	if (pmsu_mp_base == NULL)
230 		return -EINVAL;
231 
232 	/*
233 	 * Adjust the PMSU configuration to wait for WFI signal, enable
234 	 * IRQ and FIQ as wakeup events, set wait for snoop queue empty
235 	 * indication and mask IRQ and FIQ from CPU
236 	 */
237 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
238 	reg |= PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT    |
239 	       PMSU_STATUS_AND_MASK_IRQ_WAKEUP       |
240 	       PMSU_STATUS_AND_MASK_FIQ_WAKEUP       |
241 	       PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT |
242 	       PMSU_STATUS_AND_MASK_IRQ_MASK         |
243 	       PMSU_STATUS_AND_MASK_FIQ_MASK;
244 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
245 
246 	reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
247 	/* ask HW to power down the L2 Cache if needed */
248 	if (flags & PMSU_PREPARE_DEEP_IDLE)
249 		reg |= PMSU_CONTROL_AND_CONFIG_L2_PWDDN;
250 
251 	/* request power down */
252 	reg |= PMSU_CONTROL_AND_CONFIG_PWDDN_REQ;
253 	writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
254 
255 	if (flags & PMSU_PREPARE_SNOOP_DISABLE) {
256 		/* Disable snoop disable by HW - SW is taking care of it */
257 		reg = readl(pmsu_mp_base + PMSU_CPU_POWER_DOWN_CONTROL(hw_cpu));
258 		reg |= PMSU_CPU_POWER_DOWN_DIS_SNP_Q_SKIP;
259 		writel(reg, pmsu_mp_base + PMSU_CPU_POWER_DOWN_CONTROL(hw_cpu));
260 	}
261 
262 	return 0;
263 }
264 
265 int armada_370_xp_pmsu_idle_enter(unsigned long deepidle)
266 {
267 	unsigned long flags = PMSU_PREPARE_SNOOP_DISABLE;
268 	int ret;
269 
270 	if (deepidle)
271 		flags |= PMSU_PREPARE_DEEP_IDLE;
272 
273 	ret = mvebu_v7_pmsu_idle_prepare(flags);
274 	if (ret)
275 		return ret;
276 
277 	v7_exit_coherency_flush(all);
278 
279 	ll_disable_coherency();
280 
281 	dsb();
282 
283 	wfi();
284 
285 	/* If we are here, wfi failed. As processors run out of
286 	 * coherency for some time, tlbs might be stale, so flush them
287 	 */
288 	local_flush_tlb_all();
289 
290 	ll_enable_coherency();
291 
292 	/* Test the CR_C bit and set it if it was cleared */
293 	asm volatile(
294 	".arch	armv7-a\n\t"
295 	"mrc	p15, 0, r0, c1, c0, 0 \n\t"
296 	"tst	r0, %0 \n\t"
297 	"orreq	r0, r0, #(1 << 2) \n\t"
298 	"mcreq	p15, 0, r0, c1, c0, 0 \n\t"
299 	"isb	"
300 	: : "Ir" (CR_C) : "r0");
301 
302 	pr_debug("Failed to suspend the system\n");
303 
304 	return 0;
305 }
306 
307 static int armada_370_xp_cpu_suspend(unsigned long deepidle)
308 {
309 	return cpu_suspend(deepidle, armada_370_xp_pmsu_idle_enter);
310 }
311 
312 int armada_38x_do_cpu_suspend(unsigned long deepidle)
313 {
314 	unsigned long flags = 0;
315 
316 	if (deepidle)
317 		flags |= PMSU_PREPARE_DEEP_IDLE;
318 
319 	mvebu_v7_pmsu_idle_prepare(flags);
320 	/*
321 	 * Already flushed cache, but do it again as the outer cache
322 	 * functions dirty the cache with spinlocks
323 	 */
324 	v7_exit_coherency_flush(louis);
325 
326 	scu_power_mode(mvebu_get_scu_base(), SCU_PM_POWEROFF);
327 
328 	cpu_do_idle();
329 
330 	return 1;
331 }
332 
333 static int armada_38x_cpu_suspend(unsigned long deepidle)
334 {
335 	return cpu_suspend(false, armada_38x_do_cpu_suspend);
336 }
337 
338 /* No locking is needed because we only access per-CPU registers */
339 void mvebu_v7_pmsu_idle_exit(void)
340 {
341 	unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
342 	u32 reg;
343 
344 	if (pmsu_mp_base == NULL)
345 		return;
346 	/* cancel ask HW to power down the L2 Cache if possible */
347 	reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
348 	reg &= ~PMSU_CONTROL_AND_CONFIG_L2_PWDDN;
349 	writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
350 
351 	/* cancel Enable wakeup events and mask interrupts */
352 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
353 	reg &= ~(PMSU_STATUS_AND_MASK_IRQ_WAKEUP | PMSU_STATUS_AND_MASK_FIQ_WAKEUP);
354 	reg &= ~PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT;
355 	reg &= ~PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT;
356 	reg &= ~(PMSU_STATUS_AND_MASK_IRQ_MASK | PMSU_STATUS_AND_MASK_FIQ_MASK);
357 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
358 }
359 
360 static int mvebu_v7_cpu_pm_notify(struct notifier_block *self,
361 				    unsigned long action, void *hcpu)
362 {
363 	if (action == CPU_PM_ENTER) {
364 		unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
365 		mvebu_pmsu_set_cpu_boot_addr(hw_cpu, mvebu_cpu_resume);
366 	} else if (action == CPU_PM_EXIT) {
367 		mvebu_v7_pmsu_idle_exit();
368 	}
369 
370 	return NOTIFY_OK;
371 }
372 
373 static struct notifier_block mvebu_v7_cpu_pm_notifier = {
374 	.notifier_call = mvebu_v7_cpu_pm_notify,
375 };
376 
377 static struct platform_device mvebu_v7_cpuidle_device;
378 
379 static int broken_idle(struct device_node *np)
380 {
381 	if (of_property_read_bool(np, "broken-idle")) {
382 		pr_warn("CPU idle is currently broken: disabling\n");
383 		return 1;
384 	}
385 
386 	return 0;
387 }
388 
389 static __init int armada_370_cpuidle_init(void)
390 {
391 	struct device_node *np;
392 	phys_addr_t redirect_reg;
393 
394 	np = of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric");
395 	if (!np)
396 		return -ENODEV;
397 
398 	if (broken_idle(np))
399 		goto end;
400 
401 	/*
402 	 * On Armada 370, there is "a slow exit process from the deep
403 	 * idle state due to heavy L1/L2 cache cleanup operations
404 	 * performed by the BootROM software". To avoid this, we
405 	 * replace the restart code of the bootrom by a a simple jump
406 	 * to the boot address. Then the code located at this boot
407 	 * address will take care of the initialization.
408 	 */
409 	redirect_reg = pmsu_mp_phys_base + PMSU_BOOT_ADDR_REDIRECT_OFFSET(0);
410 	mvebu_setup_boot_addr_wa(ARMADA_370_CRYPT0_ENG_TARGET,
411 				 ARMADA_370_CRYPT0_ENG_ATTR,
412 				 redirect_reg);
413 
414 	mvebu_cpu_resume = armada_370_xp_cpu_resume;
415 	mvebu_v7_cpuidle_device.dev.platform_data = armada_370_xp_cpu_suspend;
416 	mvebu_v7_cpuidle_device.name = "cpuidle-armada-370";
417 
418 end:
419 	of_node_put(np);
420 	return 0;
421 }
422 
423 static __init int armada_38x_cpuidle_init(void)
424 {
425 	struct device_node *np;
426 	void __iomem *mpsoc_base;
427 	u32 reg;
428 
429 	pr_warn("CPU idle is currently broken on Armada 38x: disabling\n");
430 	return 0;
431 
432 	np = of_find_compatible_node(NULL, NULL,
433 				     "marvell,armada-380-coherency-fabric");
434 	if (!np)
435 		return -ENODEV;
436 
437 	if (broken_idle(np))
438 		goto end;
439 
440 	of_node_put(np);
441 
442 	np = of_find_compatible_node(NULL, NULL,
443 				     "marvell,armada-380-mpcore-soc-ctrl");
444 	if (!np)
445 		return -ENODEV;
446 	mpsoc_base = of_iomap(np, 0);
447 	BUG_ON(!mpsoc_base);
448 
449 	/* Set up reset mask when powering down the cpus */
450 	reg = readl(mpsoc_base + MPCORE_RESET_CTL);
451 	reg |= MPCORE_RESET_CTL_L2;
452 	reg |= MPCORE_RESET_CTL_DEBUG;
453 	writel(reg, mpsoc_base + MPCORE_RESET_CTL);
454 	iounmap(mpsoc_base);
455 
456 	/* Set up delay */
457 	reg = readl(pmsu_mp_base + PMSU_POWERDOWN_DELAY);
458 	reg &= ~PMSU_POWERDOWN_DELAY_MASK;
459 	reg |= PMSU_DFLT_ARMADA38X_DELAY;
460 	reg |= PMSU_POWERDOWN_DELAY_PMU;
461 	writel(reg, pmsu_mp_base + PMSU_POWERDOWN_DELAY);
462 
463 	mvebu_cpu_resume = armada_38x_cpu_resume;
464 	mvebu_v7_cpuidle_device.dev.platform_data = armada_38x_cpu_suspend;
465 	mvebu_v7_cpuidle_device.name = "cpuidle-armada-38x";
466 
467 end:
468 	of_node_put(np);
469 	return 0;
470 }
471 
472 static __init int armada_xp_cpuidle_init(void)
473 {
474 	struct device_node *np;
475 
476 	np = of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric");
477 	if (!np)
478 		return -ENODEV;
479 
480 	if (broken_idle(np))
481 		goto end;
482 
483 	mvebu_cpu_resume = armada_370_xp_cpu_resume;
484 	mvebu_v7_cpuidle_device.dev.platform_data = armada_370_xp_cpu_suspend;
485 	mvebu_v7_cpuidle_device.name = "cpuidle-armada-xp";
486 
487 end:
488 	of_node_put(np);
489 	return 0;
490 }
491 
492 static int __init mvebu_v7_cpu_pm_init(void)
493 {
494 	struct device_node *np;
495 	int ret;
496 
497 	np = of_find_matching_node(NULL, of_pmsu_table);
498 	if (!np)
499 		return 0;
500 	of_node_put(np);
501 
502 	/*
503 	 * Currently the CPU idle support for Armada 38x is broken, as
504 	 * the CPU hotplug uses some of the CPU idle functions it is
505 	 * broken too, so let's disable it
506 	 */
507 	if (of_machine_is_compatible("marvell,armada380")) {
508 		cpu_hotplug_disable();
509 		pr_warn("CPU hotplug support is currently broken on Armada 38x: disabling\n");
510 	}
511 
512 	if (of_machine_is_compatible("marvell,armadaxp"))
513 		ret = armada_xp_cpuidle_init();
514 	else if (of_machine_is_compatible("marvell,armada370"))
515 		ret = armada_370_cpuidle_init();
516 	else if (of_machine_is_compatible("marvell,armada380"))
517 		ret = armada_38x_cpuidle_init();
518 	else
519 		return 0;
520 
521 	if (ret)
522 		return ret;
523 
524 	mvebu_v7_pmsu_enable_l2_powerdown_onidle();
525 	if (mvebu_v7_cpuidle_device.name)
526 		platform_device_register(&mvebu_v7_cpuidle_device);
527 	cpu_pm_register_notifier(&mvebu_v7_cpu_pm_notifier);
528 
529 	return 0;
530 }
531 
532 arch_initcall(mvebu_v7_cpu_pm_init);
533 early_initcall(mvebu_v7_pmsu_init);
534 
535 static void mvebu_pmsu_dfs_request_local(void *data)
536 {
537 	u32 reg;
538 	u32 cpu = smp_processor_id();
539 	unsigned long flags;
540 
541 	local_irq_save(flags);
542 
543 	/* Prepare to enter idle */
544 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
545 	reg |= PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT |
546 	       PMSU_STATUS_AND_MASK_IRQ_MASK     |
547 	       PMSU_STATUS_AND_MASK_FIQ_MASK;
548 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
549 
550 	/* Request the DFS transition */
551 	reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(cpu));
552 	reg |= PMSU_CONTROL_AND_CONFIG_DFS_REQ;
553 	writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(cpu));
554 
555 	/* The fact of entering idle will trigger the DFS transition */
556 	wfi();
557 
558 	/*
559 	 * We're back from idle, the DFS transition has completed,
560 	 * clear the idle wait indication.
561 	 */
562 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
563 	reg &= ~PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT;
564 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
565 
566 	local_irq_restore(flags);
567 }
568 
569 int mvebu_pmsu_dfs_request(int cpu)
570 {
571 	unsigned long timeout;
572 	int hwcpu = cpu_logical_map(cpu);
573 	u32 reg;
574 
575 	/* Clear any previous DFS DONE event */
576 	reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
577 	reg &= ~PMSU_EVENT_STATUS_AND_MASK_DFS_DONE;
578 	writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
579 
580 	/* Mask the DFS done interrupt, since we are going to poll */
581 	reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
582 	reg |= PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK;
583 	writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
584 
585 	/* Trigger the DFS on the appropriate CPU */
586 	smp_call_function_single(cpu, mvebu_pmsu_dfs_request_local,
587 				 NULL, false);
588 
589 	/* Poll until the DFS done event is generated */
590 	timeout = jiffies + HZ;
591 	while (time_before(jiffies, timeout)) {
592 		reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
593 		if (reg & PMSU_EVENT_STATUS_AND_MASK_DFS_DONE)
594 			break;
595 		udelay(10);
596 	}
597 
598 	if (time_after(jiffies, timeout))
599 		return -ETIME;
600 
601 	/* Restore the DFS mask to its original state */
602 	reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
603 	reg &= ~PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK;
604 	writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
605 
606 	return 0;
607 }
608