xref: /openbmc/linux/arch/arm/mach-mvebu/pmsu.c (revision 78700c0a)
1 /*
2  * Power Management Service Unit(PMSU) support for Armada 370/XP platforms.
3  *
4  * Copyright (C) 2012 Marvell
5  *
6  * Yehuda Yitschak <yehuday@marvell.com>
7  * Gregory Clement <gregory.clement@free-electrons.com>
8  * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
9  *
10  * This file is licensed under the terms of the GNU General Public
11  * License version 2.  This program is licensed "as is" without any
12  * warranty of any kind, whether express or implied.
13  *
14  * The Armada 370 and Armada XP SOCs have a power management service
15  * unit which is responsible for powering down and waking up CPUs and
16  * other SOC units
17  */
18 
19 #define pr_fmt(fmt) "mvebu-pmsu: " fmt
20 
21 #include <linux/clk.h>
22 #include <linux/cpu_pm.h>
23 #include <linux/delay.h>
24 #include <linux/init.h>
25 #include <linux/io.h>
26 #include <linux/kernel.h>
27 #include <linux/mbus.h>
28 #include <linux/of_address.h>
29 #include <linux/of_device.h>
30 #include <linux/platform_device.h>
31 #include <linux/resource.h>
32 #include <linux/slab.h>
33 #include <linux/smp.h>
34 #include <asm/cacheflush.h>
35 #include <asm/cp15.h>
36 #include <asm/smp_scu.h>
37 #include <asm/smp_plat.h>
38 #include <asm/suspend.h>
39 #include <asm/tlbflush.h>
40 #include "common.h"
41 
42 
43 #define PMSU_BASE_OFFSET    0x100
44 #define PMSU_REG_SIZE	    0x1000
45 
46 /* PMSU MP registers */
47 #define PMSU_CONTROL_AND_CONFIG(cpu)	    ((cpu * 0x100) + 0x104)
48 #define PMSU_CONTROL_AND_CONFIG_DFS_REQ		BIT(18)
49 #define PMSU_CONTROL_AND_CONFIG_PWDDN_REQ	BIT(16)
50 #define PMSU_CONTROL_AND_CONFIG_L2_PWDDN	BIT(20)
51 
52 #define PMSU_CPU_POWER_DOWN_CONTROL(cpu)    ((cpu * 0x100) + 0x108)
53 
54 #define PMSU_CPU_POWER_DOWN_DIS_SNP_Q_SKIP	BIT(0)
55 
56 #define PMSU_STATUS_AND_MASK(cpu)	    ((cpu * 0x100) + 0x10c)
57 #define PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT	BIT(16)
58 #define PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT	BIT(17)
59 #define PMSU_STATUS_AND_MASK_IRQ_WAKEUP		BIT(20)
60 #define PMSU_STATUS_AND_MASK_FIQ_WAKEUP		BIT(21)
61 #define PMSU_STATUS_AND_MASK_DBG_WAKEUP		BIT(22)
62 #define PMSU_STATUS_AND_MASK_IRQ_MASK		BIT(24)
63 #define PMSU_STATUS_AND_MASK_FIQ_MASK		BIT(25)
64 
65 #define PMSU_EVENT_STATUS_AND_MASK(cpu)     ((cpu * 0x100) + 0x120)
66 #define PMSU_EVENT_STATUS_AND_MASK_DFS_DONE        BIT(1)
67 #define PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK   BIT(17)
68 
69 #define PMSU_BOOT_ADDR_REDIRECT_OFFSET(cpu) ((cpu * 0x100) + 0x124)
70 
71 /* PMSU fabric registers */
72 #define L2C_NFABRIC_PM_CTL		    0x4
73 #define L2C_NFABRIC_PM_CTL_PWR_DOWN		BIT(20)
74 
75 /* PMSU delay registers */
76 #define PMSU_POWERDOWN_DELAY		    0xF04
77 #define PMSU_POWERDOWN_DELAY_PMU		BIT(1)
78 #define PMSU_POWERDOWN_DELAY_MASK		0xFFFE
79 #define PMSU_DFLT_ARMADA38X_DELAY	        0x64
80 
81 /* CA9 MPcore SoC Control registers */
82 
83 #define MPCORE_RESET_CTL		    0x64
84 #define MPCORE_RESET_CTL_L2			BIT(0)
85 #define MPCORE_RESET_CTL_DEBUG			BIT(16)
86 
87 #define SRAM_PHYS_BASE  0xFFFF0000
88 #define BOOTROM_BASE    0xFFF00000
89 #define BOOTROM_SIZE    0x100000
90 
91 #define ARMADA_370_CRYPT0_ENG_TARGET   0x9
92 #define ARMADA_370_CRYPT0_ENG_ATTR     0x1
93 
94 extern void ll_disable_coherency(void);
95 extern void ll_enable_coherency(void);
96 
97 extern void armada_370_xp_cpu_resume(void);
98 extern void armada_38x_cpu_resume(void);
99 
100 static phys_addr_t pmsu_mp_phys_base;
101 static void __iomem *pmsu_mp_base;
102 
103 static void *mvebu_cpu_resume;
104 
105 static const struct of_device_id of_pmsu_table[] = {
106 	{ .compatible = "marvell,armada-370-pmsu", },
107 	{ .compatible = "marvell,armada-370-xp-pmsu", },
108 	{ .compatible = "marvell,armada-380-pmsu", },
109 	{ /* end of list */ },
110 };
111 
112 void mvebu_pmsu_set_cpu_boot_addr(int hw_cpu, void *boot_addr)
113 {
114 	writel(virt_to_phys(boot_addr), pmsu_mp_base +
115 		PMSU_BOOT_ADDR_REDIRECT_OFFSET(hw_cpu));
116 }
117 
118 extern unsigned char mvebu_boot_wa_start;
119 extern unsigned char mvebu_boot_wa_end;
120 
121 /*
122  * This function sets up the boot address workaround needed for SMP
123  * boot on Armada 375 Z1 and cpuidle on Armada 370. It unmaps the
124  * BootROM Mbus window, and instead remaps a crypto SRAM into which a
125  * custom piece of code is copied to replace the problematic BootROM.
126  */
127 int mvebu_setup_boot_addr_wa(unsigned int crypto_eng_target,
128 			     unsigned int crypto_eng_attribute,
129 			     phys_addr_t resume_addr_reg)
130 {
131 	void __iomem *sram_virt_base;
132 	u32 code_len = &mvebu_boot_wa_end - &mvebu_boot_wa_start;
133 
134 	mvebu_mbus_del_window(BOOTROM_BASE, BOOTROM_SIZE);
135 	mvebu_mbus_add_window_by_id(crypto_eng_target, crypto_eng_attribute,
136 				    SRAM_PHYS_BASE, SZ_64K);
137 
138 	sram_virt_base = ioremap(SRAM_PHYS_BASE, SZ_64K);
139 	if (!sram_virt_base) {
140 		pr_err("Unable to map SRAM to setup the boot address WA\n");
141 		return -ENOMEM;
142 	}
143 
144 	memcpy(sram_virt_base, &mvebu_boot_wa_start, code_len);
145 
146 	/*
147 	 * The last word of the code copied in SRAM must contain the
148 	 * physical base address of the PMSU register. We
149 	 * intentionally store this address in the native endianness
150 	 * of the system.
151 	 */
152 	__raw_writel((unsigned long)resume_addr_reg,
153 		     sram_virt_base + code_len - 4);
154 
155 	iounmap(sram_virt_base);
156 
157 	return 0;
158 }
159 
160 static int __init mvebu_v7_pmsu_init(void)
161 {
162 	struct device_node *np;
163 	struct resource res;
164 	int ret = 0;
165 
166 	np = of_find_matching_node(NULL, of_pmsu_table);
167 	if (!np)
168 		return 0;
169 
170 	pr_info("Initializing Power Management Service Unit\n");
171 
172 	if (of_address_to_resource(np, 0, &res)) {
173 		pr_err("unable to get resource\n");
174 		ret = -ENOENT;
175 		goto out;
176 	}
177 
178 	if (of_device_is_compatible(np, "marvell,armada-370-xp-pmsu")) {
179 		pr_warn(FW_WARN "deprecated pmsu binding\n");
180 		res.start = res.start - PMSU_BASE_OFFSET;
181 		res.end = res.start + PMSU_REG_SIZE - 1;
182 	}
183 
184 	if (!request_mem_region(res.start, resource_size(&res),
185 				np->full_name)) {
186 		pr_err("unable to request region\n");
187 		ret = -EBUSY;
188 		goto out;
189 	}
190 
191 	pmsu_mp_phys_base = res.start;
192 
193 	pmsu_mp_base = ioremap(res.start, resource_size(&res));
194 	if (!pmsu_mp_base) {
195 		pr_err("unable to map registers\n");
196 		release_mem_region(res.start, resource_size(&res));
197 		ret = -ENOMEM;
198 		goto out;
199 	}
200 
201  out:
202 	of_node_put(np);
203 	return ret;
204 }
205 
206 static void mvebu_v7_pmsu_enable_l2_powerdown_onidle(void)
207 {
208 	u32 reg;
209 
210 	if (pmsu_mp_base == NULL)
211 		return;
212 
213 	/* Enable L2 & Fabric powerdown in Deep-Idle mode - Fabric */
214 	reg = readl(pmsu_mp_base + L2C_NFABRIC_PM_CTL);
215 	reg |= L2C_NFABRIC_PM_CTL_PWR_DOWN;
216 	writel(reg, pmsu_mp_base + L2C_NFABRIC_PM_CTL);
217 }
218 
219 enum pmsu_idle_prepare_flags {
220 	PMSU_PREPARE_NORMAL = 0,
221 	PMSU_PREPARE_DEEP_IDLE = BIT(0),
222 	PMSU_PREPARE_SNOOP_DISABLE = BIT(1),
223 };
224 
225 /* No locking is needed because we only access per-CPU registers */
226 static int mvebu_v7_pmsu_idle_prepare(unsigned long flags)
227 {
228 	unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
229 	u32 reg;
230 
231 	if (pmsu_mp_base == NULL)
232 		return -EINVAL;
233 
234 	/*
235 	 * Adjust the PMSU configuration to wait for WFI signal, enable
236 	 * IRQ and FIQ as wakeup events, set wait for snoop queue empty
237 	 * indication and mask IRQ and FIQ from CPU
238 	 */
239 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
240 	reg |= PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT    |
241 	       PMSU_STATUS_AND_MASK_IRQ_WAKEUP       |
242 	       PMSU_STATUS_AND_MASK_FIQ_WAKEUP       |
243 	       PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT |
244 	       PMSU_STATUS_AND_MASK_IRQ_MASK         |
245 	       PMSU_STATUS_AND_MASK_FIQ_MASK;
246 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
247 
248 	reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
249 	/* ask HW to power down the L2 Cache if needed */
250 	if (flags & PMSU_PREPARE_DEEP_IDLE)
251 		reg |= PMSU_CONTROL_AND_CONFIG_L2_PWDDN;
252 
253 	/* request power down */
254 	reg |= PMSU_CONTROL_AND_CONFIG_PWDDN_REQ;
255 	writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
256 
257 	if (flags & PMSU_PREPARE_SNOOP_DISABLE) {
258 		/* Disable snoop disable by HW - SW is taking care of it */
259 		reg = readl(pmsu_mp_base + PMSU_CPU_POWER_DOWN_CONTROL(hw_cpu));
260 		reg |= PMSU_CPU_POWER_DOWN_DIS_SNP_Q_SKIP;
261 		writel(reg, pmsu_mp_base + PMSU_CPU_POWER_DOWN_CONTROL(hw_cpu));
262 	}
263 
264 	return 0;
265 }
266 
267 int armada_370_xp_pmsu_idle_enter(unsigned long deepidle)
268 {
269 	unsigned long flags = PMSU_PREPARE_SNOOP_DISABLE;
270 	int ret;
271 
272 	if (deepidle)
273 		flags |= PMSU_PREPARE_DEEP_IDLE;
274 
275 	ret = mvebu_v7_pmsu_idle_prepare(flags);
276 	if (ret)
277 		return ret;
278 
279 	v7_exit_coherency_flush(all);
280 
281 	ll_disable_coherency();
282 
283 	dsb();
284 
285 	wfi();
286 
287 	/* If we are here, wfi failed. As processors run out of
288 	 * coherency for some time, tlbs might be stale, so flush them
289 	 */
290 	local_flush_tlb_all();
291 
292 	ll_enable_coherency();
293 
294 	/* Test the CR_C bit and set it if it was cleared */
295 	asm volatile(
296 	"mrc	p15, 0, r0, c1, c0, 0 \n\t"
297 	"tst	r0, %0 \n\t"
298 	"orreq	r0, r0, #(1 << 2) \n\t"
299 	"mcreq	p15, 0, r0, c1, c0, 0 \n\t"
300 	"isb	"
301 	: : "Ir" (CR_C) : "r0");
302 
303 	pr_debug("Failed to suspend the system\n");
304 
305 	return 0;
306 }
307 
308 static int armada_370_xp_cpu_suspend(unsigned long deepidle)
309 {
310 	return cpu_suspend(deepidle, armada_370_xp_pmsu_idle_enter);
311 }
312 
313 int armada_38x_do_cpu_suspend(unsigned long deepidle)
314 {
315 	unsigned long flags = 0;
316 
317 	if (deepidle)
318 		flags |= PMSU_PREPARE_DEEP_IDLE;
319 
320 	mvebu_v7_pmsu_idle_prepare(flags);
321 	/*
322 	 * Already flushed cache, but do it again as the outer cache
323 	 * functions dirty the cache with spinlocks
324 	 */
325 	v7_exit_coherency_flush(louis);
326 
327 	scu_power_mode(mvebu_get_scu_base(), SCU_PM_POWEROFF);
328 
329 	cpu_do_idle();
330 
331 	return 1;
332 }
333 
334 static int armada_38x_cpu_suspend(unsigned long deepidle)
335 {
336 	return cpu_suspend(false, armada_38x_do_cpu_suspend);
337 }
338 
339 /* No locking is needed because we only access per-CPU registers */
340 void mvebu_v7_pmsu_idle_exit(void)
341 {
342 	unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
343 	u32 reg;
344 
345 	if (pmsu_mp_base == NULL)
346 		return;
347 	/* cancel ask HW to power down the L2 Cache if possible */
348 	reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
349 	reg &= ~PMSU_CONTROL_AND_CONFIG_L2_PWDDN;
350 	writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(hw_cpu));
351 
352 	/* cancel Enable wakeup events and mask interrupts */
353 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
354 	reg &= ~(PMSU_STATUS_AND_MASK_IRQ_WAKEUP | PMSU_STATUS_AND_MASK_FIQ_WAKEUP);
355 	reg &= ~PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT;
356 	reg &= ~PMSU_STATUS_AND_MASK_SNP_Q_EMPTY_WAIT;
357 	reg &= ~(PMSU_STATUS_AND_MASK_IRQ_MASK | PMSU_STATUS_AND_MASK_FIQ_MASK);
358 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(hw_cpu));
359 }
360 
361 static int mvebu_v7_cpu_pm_notify(struct notifier_block *self,
362 				    unsigned long action, void *hcpu)
363 {
364 	if (action == CPU_PM_ENTER) {
365 		unsigned int hw_cpu = cpu_logical_map(smp_processor_id());
366 		mvebu_pmsu_set_cpu_boot_addr(hw_cpu, mvebu_cpu_resume);
367 	} else if (action == CPU_PM_EXIT) {
368 		mvebu_v7_pmsu_idle_exit();
369 	}
370 
371 	return NOTIFY_OK;
372 }
373 
374 static struct notifier_block mvebu_v7_cpu_pm_notifier = {
375 	.notifier_call = mvebu_v7_cpu_pm_notify,
376 };
377 
378 static struct platform_device mvebu_v7_cpuidle_device;
379 
380 static int broken_idle(struct device_node *np)
381 {
382 	if (of_property_read_bool(np, "broken-idle")) {
383 		pr_warn("CPU idle is currently broken: disabling\n");
384 		return 1;
385 	}
386 
387 	return 0;
388 }
389 
390 static __init int armada_370_cpuidle_init(void)
391 {
392 	struct device_node *np;
393 	phys_addr_t redirect_reg;
394 
395 	np = of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric");
396 	if (!np)
397 		return -ENODEV;
398 
399 	if (broken_idle(np))
400 		goto end;
401 
402 	/*
403 	 * On Armada 370, there is "a slow exit process from the deep
404 	 * idle state due to heavy L1/L2 cache cleanup operations
405 	 * performed by the BootROM software". To avoid this, we
406 	 * replace the restart code of the bootrom by a a simple jump
407 	 * to the boot address. Then the code located at this boot
408 	 * address will take care of the initialization.
409 	 */
410 	redirect_reg = pmsu_mp_phys_base + PMSU_BOOT_ADDR_REDIRECT_OFFSET(0);
411 	mvebu_setup_boot_addr_wa(ARMADA_370_CRYPT0_ENG_TARGET,
412 				 ARMADA_370_CRYPT0_ENG_ATTR,
413 				 redirect_reg);
414 
415 	mvebu_cpu_resume = armada_370_xp_cpu_resume;
416 	mvebu_v7_cpuidle_device.dev.platform_data = armada_370_xp_cpu_suspend;
417 	mvebu_v7_cpuidle_device.name = "cpuidle-armada-370";
418 
419 end:
420 	of_node_put(np);
421 	return 0;
422 }
423 
424 static __init int armada_38x_cpuidle_init(void)
425 {
426 	struct device_node *np;
427 	void __iomem *mpsoc_base;
428 	u32 reg;
429 
430 	pr_warn("CPU idle is currently broken on Armada 38x: disabling\n");
431 	return 0;
432 
433 	np = of_find_compatible_node(NULL, NULL,
434 				     "marvell,armada-380-coherency-fabric");
435 	if (!np)
436 		return -ENODEV;
437 
438 	if (broken_idle(np))
439 		goto end;
440 
441 	of_node_put(np);
442 
443 	np = of_find_compatible_node(NULL, NULL,
444 				     "marvell,armada-380-mpcore-soc-ctrl");
445 	if (!np)
446 		return -ENODEV;
447 	mpsoc_base = of_iomap(np, 0);
448 	BUG_ON(!mpsoc_base);
449 
450 	/* Set up reset mask when powering down the cpus */
451 	reg = readl(mpsoc_base + MPCORE_RESET_CTL);
452 	reg |= MPCORE_RESET_CTL_L2;
453 	reg |= MPCORE_RESET_CTL_DEBUG;
454 	writel(reg, mpsoc_base + MPCORE_RESET_CTL);
455 	iounmap(mpsoc_base);
456 
457 	/* Set up delay */
458 	reg = readl(pmsu_mp_base + PMSU_POWERDOWN_DELAY);
459 	reg &= ~PMSU_POWERDOWN_DELAY_MASK;
460 	reg |= PMSU_DFLT_ARMADA38X_DELAY;
461 	reg |= PMSU_POWERDOWN_DELAY_PMU;
462 	writel(reg, pmsu_mp_base + PMSU_POWERDOWN_DELAY);
463 
464 	mvebu_cpu_resume = armada_38x_cpu_resume;
465 	mvebu_v7_cpuidle_device.dev.platform_data = armada_38x_cpu_suspend;
466 	mvebu_v7_cpuidle_device.name = "cpuidle-armada-38x";
467 
468 end:
469 	of_node_put(np);
470 	return 0;
471 }
472 
473 static __init int armada_xp_cpuidle_init(void)
474 {
475 	struct device_node *np;
476 
477 	np = of_find_compatible_node(NULL, NULL, "marvell,coherency-fabric");
478 	if (!np)
479 		return -ENODEV;
480 
481 	if (broken_idle(np))
482 		goto end;
483 
484 	mvebu_cpu_resume = armada_370_xp_cpu_resume;
485 	mvebu_v7_cpuidle_device.dev.platform_data = armada_370_xp_cpu_suspend;
486 	mvebu_v7_cpuidle_device.name = "cpuidle-armada-xp";
487 
488 end:
489 	of_node_put(np);
490 	return 0;
491 }
492 
493 static int __init mvebu_v7_cpu_pm_init(void)
494 {
495 	struct device_node *np;
496 	int ret;
497 
498 	np = of_find_matching_node(NULL, of_pmsu_table);
499 	if (!np)
500 		return 0;
501 	of_node_put(np);
502 
503 	/*
504 	 * Currently the CPU idle support for Armada 38x is broken, as
505 	 * the CPU hotplug uses some of the CPU idle functions it is
506 	 * broken too, so let's disable it
507 	 */
508 	if (of_machine_is_compatible("marvell,armada380")) {
509 		cpu_hotplug_disable();
510 		pr_warn("CPU hotplug support is currently broken on Armada 38x: disabling\n");
511 	}
512 
513 	if (of_machine_is_compatible("marvell,armadaxp"))
514 		ret = armada_xp_cpuidle_init();
515 	else if (of_machine_is_compatible("marvell,armada370"))
516 		ret = armada_370_cpuidle_init();
517 	else if (of_machine_is_compatible("marvell,armada380"))
518 		ret = armada_38x_cpuidle_init();
519 	else
520 		return 0;
521 
522 	if (ret)
523 		return ret;
524 
525 	mvebu_v7_pmsu_enable_l2_powerdown_onidle();
526 	if (mvebu_v7_cpuidle_device.name)
527 		platform_device_register(&mvebu_v7_cpuidle_device);
528 	cpu_pm_register_notifier(&mvebu_v7_cpu_pm_notifier);
529 
530 	return 0;
531 }
532 
533 arch_initcall(mvebu_v7_cpu_pm_init);
534 early_initcall(mvebu_v7_pmsu_init);
535 
536 static void mvebu_pmsu_dfs_request_local(void *data)
537 {
538 	u32 reg;
539 	u32 cpu = smp_processor_id();
540 	unsigned long flags;
541 
542 	local_irq_save(flags);
543 
544 	/* Prepare to enter idle */
545 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
546 	reg |= PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT |
547 	       PMSU_STATUS_AND_MASK_IRQ_MASK     |
548 	       PMSU_STATUS_AND_MASK_FIQ_MASK;
549 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
550 
551 	/* Request the DFS transition */
552 	reg = readl(pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(cpu));
553 	reg |= PMSU_CONTROL_AND_CONFIG_DFS_REQ;
554 	writel(reg, pmsu_mp_base + PMSU_CONTROL_AND_CONFIG(cpu));
555 
556 	/* The fact of entering idle will trigger the DFS transition */
557 	wfi();
558 
559 	/*
560 	 * We're back from idle, the DFS transition has completed,
561 	 * clear the idle wait indication.
562 	 */
563 	reg = readl(pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
564 	reg &= ~PMSU_STATUS_AND_MASK_CPU_IDLE_WAIT;
565 	writel(reg, pmsu_mp_base + PMSU_STATUS_AND_MASK(cpu));
566 
567 	local_irq_restore(flags);
568 }
569 
570 int mvebu_pmsu_dfs_request(int cpu)
571 {
572 	unsigned long timeout;
573 	int hwcpu = cpu_logical_map(cpu);
574 	u32 reg;
575 
576 	/* Clear any previous DFS DONE event */
577 	reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
578 	reg &= ~PMSU_EVENT_STATUS_AND_MASK_DFS_DONE;
579 	writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
580 
581 	/* Mask the DFS done interrupt, since we are going to poll */
582 	reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
583 	reg |= PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK;
584 	writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
585 
586 	/* Trigger the DFS on the appropriate CPU */
587 	smp_call_function_single(cpu, mvebu_pmsu_dfs_request_local,
588 				 NULL, false);
589 
590 	/* Poll until the DFS done event is generated */
591 	timeout = jiffies + HZ;
592 	while (time_before(jiffies, timeout)) {
593 		reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
594 		if (reg & PMSU_EVENT_STATUS_AND_MASK_DFS_DONE)
595 			break;
596 		udelay(10);
597 	}
598 
599 	if (time_after(jiffies, timeout))
600 		return -ETIME;
601 
602 	/* Restore the DFS mask to its original state */
603 	reg = readl(pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
604 	reg &= ~PMSU_EVENT_STATUS_AND_MASK_DFS_DONE_MASK;
605 	writel(reg, pmsu_mp_base + PMSU_EVENT_STATUS_AND_MASK(hwcpu));
606 
607 	return 0;
608 }
609