xref: /openbmc/linux/arch/x86/kernel/hpet.c (revision b868a02e)
1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/clockchips.h>
3 #include <linux/interrupt.h>
4 #include <linux/export.h>
5 #include <linux/delay.h>
6 #include <linux/hpet.h>
7 #include <linux/cpu.h>
8 #include <linux/irq.h>
9 
10 #include <asm/irq_remapping.h>
11 #include <asm/hpet.h>
12 #include <asm/time.h>
13 #include <asm/mwait.h>
14 
15 #undef  pr_fmt
16 #define pr_fmt(fmt) "hpet: " fmt
17 
18 enum hpet_mode {
19 	HPET_MODE_UNUSED,
20 	HPET_MODE_LEGACY,
21 	HPET_MODE_CLOCKEVT,
22 	HPET_MODE_DEVICE,
23 };
24 
25 struct hpet_channel {
26 	struct clock_event_device	evt;
27 	unsigned int			num;
28 	unsigned int			cpu;
29 	unsigned int			irq;
30 	unsigned int			in_use;
31 	enum hpet_mode			mode;
32 	unsigned int			boot_cfg;
33 	char				name[10];
34 };
35 
36 struct hpet_base {
37 	unsigned int			nr_channels;
38 	unsigned int			nr_clockevents;
39 	unsigned int			boot_cfg;
40 	struct hpet_channel		*channels;
41 };
42 
43 #define HPET_MASK			CLOCKSOURCE_MASK(32)
44 
45 #define HPET_MIN_CYCLES			128
46 #define HPET_MIN_PROG_DELTA		(HPET_MIN_CYCLES + (HPET_MIN_CYCLES >> 1))
47 
48 /*
49  * HPET address is set in acpi/boot.c, when an ACPI entry exists
50  */
51 unsigned long				hpet_address;
52 u8					hpet_blockid; /* OS timer block num */
53 bool					hpet_msi_disable;
54 
55 #ifdef CONFIG_GENERIC_MSI_IRQ
56 static DEFINE_PER_CPU(struct hpet_channel *, cpu_hpet_channel);
57 static struct irq_domain		*hpet_domain;
58 #endif
59 
60 static void __iomem			*hpet_virt_address;
61 
62 static struct hpet_base			hpet_base;
63 
64 static bool				hpet_legacy_int_enabled;
65 static unsigned long			hpet_freq;
66 
67 bool					boot_hpet_disable;
68 bool					hpet_force_user;
69 static bool				hpet_verbose;
70 
71 static inline
72 struct hpet_channel *clockevent_to_channel(struct clock_event_device *evt)
73 {
74 	return container_of(evt, struct hpet_channel, evt);
75 }
76 
77 inline unsigned int hpet_readl(unsigned int a)
78 {
79 	return readl(hpet_virt_address + a);
80 }
81 
82 static inline void hpet_writel(unsigned int d, unsigned int a)
83 {
84 	writel(d, hpet_virt_address + a);
85 }
86 
87 static inline void hpet_set_mapping(void)
88 {
89 	hpet_virt_address = ioremap(hpet_address, HPET_MMAP_SIZE);
90 }
91 
92 static inline void hpet_clear_mapping(void)
93 {
94 	iounmap(hpet_virt_address);
95 	hpet_virt_address = NULL;
96 }
97 
98 /*
99  * HPET command line enable / disable
100  */
101 static int __init hpet_setup(char *str)
102 {
103 	while (str) {
104 		char *next = strchr(str, ',');
105 
106 		if (next)
107 			*next++ = 0;
108 		if (!strncmp("disable", str, 7))
109 			boot_hpet_disable = true;
110 		if (!strncmp("force", str, 5))
111 			hpet_force_user = true;
112 		if (!strncmp("verbose", str, 7))
113 			hpet_verbose = true;
114 		str = next;
115 	}
116 	return 1;
117 }
118 __setup("hpet=", hpet_setup);
119 
120 static int __init disable_hpet(char *str)
121 {
122 	boot_hpet_disable = true;
123 	return 1;
124 }
125 __setup("nohpet", disable_hpet);
126 
127 static inline int is_hpet_capable(void)
128 {
129 	return !boot_hpet_disable && hpet_address;
130 }
131 
132 /**
133  * is_hpet_enabled - Check whether the legacy HPET timer interrupt is enabled
134  */
135 int is_hpet_enabled(void)
136 {
137 	return is_hpet_capable() && hpet_legacy_int_enabled;
138 }
139 EXPORT_SYMBOL_GPL(is_hpet_enabled);
140 
141 static void _hpet_print_config(const char *function, int line)
142 {
143 	u32 i, id, period, cfg, status, channels, l, h;
144 
145 	pr_info("%s(%d):\n", function, line);
146 
147 	id = hpet_readl(HPET_ID);
148 	period = hpet_readl(HPET_PERIOD);
149 	pr_info("ID: 0x%x, PERIOD: 0x%x\n", id, period);
150 
151 	cfg = hpet_readl(HPET_CFG);
152 	status = hpet_readl(HPET_STATUS);
153 	pr_info("CFG: 0x%x, STATUS: 0x%x\n", cfg, status);
154 
155 	l = hpet_readl(HPET_COUNTER);
156 	h = hpet_readl(HPET_COUNTER+4);
157 	pr_info("COUNTER_l: 0x%x, COUNTER_h: 0x%x\n", l, h);
158 
159 	channels = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
160 
161 	for (i = 0; i < channels; i++) {
162 		l = hpet_readl(HPET_Tn_CFG(i));
163 		h = hpet_readl(HPET_Tn_CFG(i)+4);
164 		pr_info("T%d: CFG_l: 0x%x, CFG_h: 0x%x\n", i, l, h);
165 
166 		l = hpet_readl(HPET_Tn_CMP(i));
167 		h = hpet_readl(HPET_Tn_CMP(i)+4);
168 		pr_info("T%d: CMP_l: 0x%x, CMP_h: 0x%x\n", i, l, h);
169 
170 		l = hpet_readl(HPET_Tn_ROUTE(i));
171 		h = hpet_readl(HPET_Tn_ROUTE(i)+4);
172 		pr_info("T%d ROUTE_l: 0x%x, ROUTE_h: 0x%x\n", i, l, h);
173 	}
174 }
175 
176 #define hpet_print_config()					\
177 do {								\
178 	if (hpet_verbose)					\
179 		_hpet_print_config(__func__, __LINE__);	\
180 } while (0)
181 
182 /*
183  * When the HPET driver (/dev/hpet) is enabled, we need to reserve
184  * timer 0 and timer 1 in case of RTC emulation.
185  */
186 #ifdef CONFIG_HPET
187 
188 static void __init hpet_reserve_platform_timers(void)
189 {
190 	struct hpet_data hd;
191 	unsigned int i;
192 
193 	memset(&hd, 0, sizeof(hd));
194 	hd.hd_phys_address	= hpet_address;
195 	hd.hd_address		= hpet_virt_address;
196 	hd.hd_nirqs		= hpet_base.nr_channels;
197 
198 	/*
199 	 * NOTE that hd_irq[] reflects IOAPIC input pins (LEGACY_8254
200 	 * is wrong for i8259!) not the output IRQ.  Many BIOS writers
201 	 * don't bother configuring *any* comparator interrupts.
202 	 */
203 	hd.hd_irq[0] = HPET_LEGACY_8254;
204 	hd.hd_irq[1] = HPET_LEGACY_RTC;
205 
206 	for (i = 0; i < hpet_base.nr_channels; i++) {
207 		struct hpet_channel *hc = hpet_base.channels + i;
208 
209 		if (i >= 2)
210 			hd.hd_irq[i] = hc->irq;
211 
212 		switch (hc->mode) {
213 		case HPET_MODE_UNUSED:
214 		case HPET_MODE_DEVICE:
215 			hc->mode = HPET_MODE_DEVICE;
216 			break;
217 		case HPET_MODE_CLOCKEVT:
218 		case HPET_MODE_LEGACY:
219 			hpet_reserve_timer(&hd, hc->num);
220 			break;
221 		}
222 	}
223 
224 	hpet_alloc(&hd);
225 }
226 
227 static void __init hpet_select_device_channel(void)
228 {
229 	int i;
230 
231 	for (i = 0; i < hpet_base.nr_channels; i++) {
232 		struct hpet_channel *hc = hpet_base.channels + i;
233 
234 		/* Associate the first unused channel to /dev/hpet */
235 		if (hc->mode == HPET_MODE_UNUSED) {
236 			hc->mode = HPET_MODE_DEVICE;
237 			return;
238 		}
239 	}
240 }
241 
242 #else
243 static inline void hpet_reserve_platform_timers(void) { }
244 static inline void hpet_select_device_channel(void) {}
245 #endif
246 
247 /* Common HPET functions */
248 static void hpet_stop_counter(void)
249 {
250 	u32 cfg = hpet_readl(HPET_CFG);
251 
252 	cfg &= ~HPET_CFG_ENABLE;
253 	hpet_writel(cfg, HPET_CFG);
254 }
255 
256 static void hpet_reset_counter(void)
257 {
258 	hpet_writel(0, HPET_COUNTER);
259 	hpet_writel(0, HPET_COUNTER + 4);
260 }
261 
262 static void hpet_start_counter(void)
263 {
264 	unsigned int cfg = hpet_readl(HPET_CFG);
265 
266 	cfg |= HPET_CFG_ENABLE;
267 	hpet_writel(cfg, HPET_CFG);
268 }
269 
270 static void hpet_restart_counter(void)
271 {
272 	hpet_stop_counter();
273 	hpet_reset_counter();
274 	hpet_start_counter();
275 }
276 
277 static void hpet_resume_device(void)
278 {
279 	force_hpet_resume();
280 }
281 
282 static void hpet_resume_counter(struct clocksource *cs)
283 {
284 	hpet_resume_device();
285 	hpet_restart_counter();
286 }
287 
288 static void hpet_enable_legacy_int(void)
289 {
290 	unsigned int cfg = hpet_readl(HPET_CFG);
291 
292 	cfg |= HPET_CFG_LEGACY;
293 	hpet_writel(cfg, HPET_CFG);
294 	hpet_legacy_int_enabled = true;
295 }
296 
297 static int hpet_clkevt_set_state_periodic(struct clock_event_device *evt)
298 {
299 	unsigned int channel = clockevent_to_channel(evt)->num;
300 	unsigned int cfg, cmp, now;
301 	uint64_t delta;
302 
303 	hpet_stop_counter();
304 	delta = ((uint64_t)(NSEC_PER_SEC / HZ)) * evt->mult;
305 	delta >>= evt->shift;
306 	now = hpet_readl(HPET_COUNTER);
307 	cmp = now + (unsigned int)delta;
308 	cfg = hpet_readl(HPET_Tn_CFG(channel));
309 	cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
310 	       HPET_TN_32BIT;
311 	hpet_writel(cfg, HPET_Tn_CFG(channel));
312 	hpet_writel(cmp, HPET_Tn_CMP(channel));
313 	udelay(1);
314 	/*
315 	 * HPET on AMD 81xx needs a second write (with HPET_TN_SETVAL
316 	 * cleared) to T0_CMP to set the period. The HPET_TN_SETVAL
317 	 * bit is automatically cleared after the first write.
318 	 * (See AMD-8111 HyperTransport I/O Hub Data Sheet,
319 	 * Publication # 24674)
320 	 */
321 	hpet_writel((unsigned int)delta, HPET_Tn_CMP(channel));
322 	hpet_start_counter();
323 	hpet_print_config();
324 
325 	return 0;
326 }
327 
328 static int hpet_clkevt_set_state_oneshot(struct clock_event_device *evt)
329 {
330 	unsigned int channel = clockevent_to_channel(evt)->num;
331 	unsigned int cfg;
332 
333 	cfg = hpet_readl(HPET_Tn_CFG(channel));
334 	cfg &= ~HPET_TN_PERIODIC;
335 	cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
336 	hpet_writel(cfg, HPET_Tn_CFG(channel));
337 
338 	return 0;
339 }
340 
341 static int hpet_clkevt_set_state_shutdown(struct clock_event_device *evt)
342 {
343 	unsigned int channel = clockevent_to_channel(evt)->num;
344 	unsigned int cfg;
345 
346 	cfg = hpet_readl(HPET_Tn_CFG(channel));
347 	cfg &= ~HPET_TN_ENABLE;
348 	hpet_writel(cfg, HPET_Tn_CFG(channel));
349 
350 	return 0;
351 }
352 
353 static int hpet_clkevt_legacy_resume(struct clock_event_device *evt)
354 {
355 	hpet_enable_legacy_int();
356 	hpet_print_config();
357 	return 0;
358 }
359 
360 static int
361 hpet_clkevt_set_next_event(unsigned long delta, struct clock_event_device *evt)
362 {
363 	unsigned int channel = clockevent_to_channel(evt)->num;
364 	u32 cnt;
365 	s32 res;
366 
367 	cnt = hpet_readl(HPET_COUNTER);
368 	cnt += (u32) delta;
369 	hpet_writel(cnt, HPET_Tn_CMP(channel));
370 
371 	/*
372 	 * HPETs are a complete disaster. The compare register is
373 	 * based on a equal comparison and neither provides a less
374 	 * than or equal functionality (which would require to take
375 	 * the wraparound into account) nor a simple count down event
376 	 * mode. Further the write to the comparator register is
377 	 * delayed internally up to two HPET clock cycles in certain
378 	 * chipsets (ATI, ICH9,10). Some newer AMD chipsets have even
379 	 * longer delays. We worked around that by reading back the
380 	 * compare register, but that required another workaround for
381 	 * ICH9,10 chips where the first readout after write can
382 	 * return the old stale value. We already had a minimum
383 	 * programming delta of 5us enforced, but a NMI or SMI hitting
384 	 * between the counter readout and the comparator write can
385 	 * move us behind that point easily. Now instead of reading
386 	 * the compare register back several times, we make the ETIME
387 	 * decision based on the following: Return ETIME if the
388 	 * counter value after the write is less than HPET_MIN_CYCLES
389 	 * away from the event or if the counter is already ahead of
390 	 * the event. The minimum programming delta for the generic
391 	 * clockevents code is set to 1.5 * HPET_MIN_CYCLES.
392 	 */
393 	res = (s32)(cnt - hpet_readl(HPET_COUNTER));
394 
395 	return res < HPET_MIN_CYCLES ? -ETIME : 0;
396 }
397 
398 static void hpet_init_clockevent(struct hpet_channel *hc, unsigned int rating)
399 {
400 	struct clock_event_device *evt = &hc->evt;
401 
402 	evt->rating		= rating;
403 	evt->irq		= hc->irq;
404 	evt->name		= hc->name;
405 	evt->cpumask		= cpumask_of(hc->cpu);
406 	evt->set_state_oneshot	= hpet_clkevt_set_state_oneshot;
407 	evt->set_next_event	= hpet_clkevt_set_next_event;
408 	evt->set_state_shutdown	= hpet_clkevt_set_state_shutdown;
409 
410 	evt->features = CLOCK_EVT_FEAT_ONESHOT;
411 	if (hc->boot_cfg & HPET_TN_PERIODIC) {
412 		evt->features		|= CLOCK_EVT_FEAT_PERIODIC;
413 		evt->set_state_periodic	= hpet_clkevt_set_state_periodic;
414 	}
415 }
416 
417 static void __init hpet_legacy_clockevent_register(struct hpet_channel *hc)
418 {
419 	/*
420 	 * Start HPET with the boot CPU's cpumask and make it global after
421 	 * the IO_APIC has been initialized.
422 	 */
423 	hc->cpu = boot_cpu_data.cpu_index;
424 	strncpy(hc->name, "hpet", sizeof(hc->name));
425 	hpet_init_clockevent(hc, 50);
426 
427 	hc->evt.tick_resume	= hpet_clkevt_legacy_resume;
428 
429 	/*
430 	 * Legacy horrors and sins from the past. HPET used periodic mode
431 	 * unconditionally forever on the legacy channel 0. Removing the
432 	 * below hack and using the conditional in hpet_init_clockevent()
433 	 * makes at least Qemu and one hardware machine fail to boot.
434 	 * There are two issues which cause the boot failure:
435 	 *
436 	 * #1 After the timer delivery test in IOAPIC and the IOAPIC setup
437 	 *    the next interrupt is not delivered despite the HPET channel
438 	 *    being programmed correctly. Reprogramming the HPET after
439 	 *    switching to IOAPIC makes it work again. After fixing this,
440 	 *    the next issue surfaces:
441 	 *
442 	 * #2 Due to the unconditional periodic mode availability the Local
443 	 *    APIC timer calibration can hijack the global clockevents
444 	 *    event handler without causing damage. Using oneshot at this
445 	 *    stage makes if hang because the HPET does not get
446 	 *    reprogrammed due to the handler hijacking. Duh, stupid me!
447 	 *
448 	 * Both issues require major surgery and especially the kick HPET
449 	 * again after enabling IOAPIC results in really nasty hackery.
450 	 * This 'assume periodic works' magic has survived since HPET
451 	 * support got added, so it's questionable whether this should be
452 	 * fixed. Both Qemu and the failing hardware machine support
453 	 * periodic mode despite the fact that both don't advertise it in
454 	 * the configuration register and both need that extra kick after
455 	 * switching to IOAPIC. Seems to be a feature...
456 	 */
457 	hc->evt.features		|= CLOCK_EVT_FEAT_PERIODIC;
458 	hc->evt.set_state_periodic	= hpet_clkevt_set_state_periodic;
459 
460 	/* Start HPET legacy interrupts */
461 	hpet_enable_legacy_int();
462 
463 	clockevents_config_and_register(&hc->evt, hpet_freq,
464 					HPET_MIN_PROG_DELTA, 0x7FFFFFFF);
465 	global_clock_event = &hc->evt;
466 	pr_debug("Clockevent registered\n");
467 }
468 
469 /*
470  * HPET MSI Support
471  */
472 #ifdef CONFIG_GENERIC_MSI_IRQ
473 static void hpet_msi_unmask(struct irq_data *data)
474 {
475 	struct hpet_channel *hc = irq_data_get_irq_handler_data(data);
476 	unsigned int cfg;
477 
478 	cfg = hpet_readl(HPET_Tn_CFG(hc->num));
479 	cfg |= HPET_TN_ENABLE | HPET_TN_FSB;
480 	hpet_writel(cfg, HPET_Tn_CFG(hc->num));
481 }
482 
483 static void hpet_msi_mask(struct irq_data *data)
484 {
485 	struct hpet_channel *hc = irq_data_get_irq_handler_data(data);
486 	unsigned int cfg;
487 
488 	cfg = hpet_readl(HPET_Tn_CFG(hc->num));
489 	cfg &= ~(HPET_TN_ENABLE | HPET_TN_FSB);
490 	hpet_writel(cfg, HPET_Tn_CFG(hc->num));
491 }
492 
493 static void hpet_msi_write(struct hpet_channel *hc, struct msi_msg *msg)
494 {
495 	hpet_writel(msg->data, HPET_Tn_ROUTE(hc->num));
496 	hpet_writel(msg->address_lo, HPET_Tn_ROUTE(hc->num) + 4);
497 }
498 
499 static void hpet_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
500 {
501 	hpet_msi_write(irq_data_get_irq_handler_data(data), msg);
502 }
503 
504 static struct irq_chip hpet_msi_controller __ro_after_init = {
505 	.name = "HPET-MSI",
506 	.irq_unmask = hpet_msi_unmask,
507 	.irq_mask = hpet_msi_mask,
508 	.irq_ack = irq_chip_ack_parent,
509 	.irq_set_affinity = msi_domain_set_affinity,
510 	.irq_retrigger = irq_chip_retrigger_hierarchy,
511 	.irq_write_msi_msg = hpet_msi_write_msg,
512 	.flags = IRQCHIP_SKIP_SET_WAKE | IRQCHIP_AFFINITY_PRE_STARTUP,
513 };
514 
515 static int hpet_msi_init(struct irq_domain *domain,
516 			 struct msi_domain_info *info, unsigned int virq,
517 			 irq_hw_number_t hwirq, msi_alloc_info_t *arg)
518 {
519 	irq_set_status_flags(virq, IRQ_MOVE_PCNTXT);
520 	irq_domain_set_info(domain, virq, arg->hwirq, info->chip, NULL,
521 			    handle_edge_irq, arg->data, "edge");
522 
523 	return 0;
524 }
525 
526 static void hpet_msi_free(struct irq_domain *domain,
527 			  struct msi_domain_info *info, unsigned int virq)
528 {
529 	irq_clear_status_flags(virq, IRQ_MOVE_PCNTXT);
530 }
531 
532 static struct msi_domain_ops hpet_msi_domain_ops = {
533 	.msi_init	= hpet_msi_init,
534 	.msi_free	= hpet_msi_free,
535 };
536 
537 static struct msi_domain_info hpet_msi_domain_info = {
538 	.ops		= &hpet_msi_domain_ops,
539 	.chip		= &hpet_msi_controller,
540 	.flags		= MSI_FLAG_USE_DEF_DOM_OPS,
541 };
542 
543 static struct irq_domain *hpet_create_irq_domain(int hpet_id)
544 {
545 	struct msi_domain_info *domain_info;
546 	struct irq_domain *parent, *d;
547 	struct fwnode_handle *fn;
548 	struct irq_fwspec fwspec;
549 
550 	if (x86_vector_domain == NULL)
551 		return NULL;
552 
553 	domain_info = kzalloc(sizeof(*domain_info), GFP_KERNEL);
554 	if (!domain_info)
555 		return NULL;
556 
557 	*domain_info = hpet_msi_domain_info;
558 	domain_info->data = (void *)(long)hpet_id;
559 
560 	fn = irq_domain_alloc_named_id_fwnode(hpet_msi_controller.name,
561 					      hpet_id);
562 	if (!fn) {
563 		kfree(domain_info);
564 		return NULL;
565 	}
566 
567 	fwspec.fwnode = fn;
568 	fwspec.param_count = 1;
569 	fwspec.param[0] = hpet_id;
570 
571 	parent = irq_find_matching_fwspec(&fwspec, DOMAIN_BUS_ANY);
572 	if (!parent) {
573 		irq_domain_free_fwnode(fn);
574 		kfree(domain_info);
575 		return NULL;
576 	}
577 	if (parent != x86_vector_domain)
578 		hpet_msi_controller.name = "IR-HPET-MSI";
579 
580 	d = msi_create_irq_domain(fn, domain_info, parent);
581 	if (!d) {
582 		irq_domain_free_fwnode(fn);
583 		kfree(domain_info);
584 	}
585 	return d;
586 }
587 
588 static inline int hpet_dev_id(struct irq_domain *domain)
589 {
590 	struct msi_domain_info *info = msi_get_domain_info(domain);
591 
592 	return (int)(long)info->data;
593 }
594 
595 static int hpet_assign_irq(struct irq_domain *domain, struct hpet_channel *hc,
596 			   int dev_num)
597 {
598 	struct irq_alloc_info info;
599 
600 	init_irq_alloc_info(&info, NULL);
601 	info.type = X86_IRQ_ALLOC_TYPE_HPET;
602 	info.data = hc;
603 	info.devid = hpet_dev_id(domain);
604 	info.hwirq = dev_num;
605 
606 	return irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, &info);
607 }
608 
609 static int hpet_clkevt_msi_resume(struct clock_event_device *evt)
610 {
611 	struct hpet_channel *hc = clockevent_to_channel(evt);
612 	struct irq_data *data = irq_get_irq_data(hc->irq);
613 	struct msi_msg msg;
614 
615 	/* Restore the MSI msg and unmask the interrupt */
616 	irq_chip_compose_msi_msg(data, &msg);
617 	hpet_msi_write(hc, &msg);
618 	hpet_msi_unmask(data);
619 	return 0;
620 }
621 
622 static irqreturn_t hpet_msi_interrupt_handler(int irq, void *data)
623 {
624 	struct hpet_channel *hc = data;
625 	struct clock_event_device *evt = &hc->evt;
626 
627 	if (!evt->event_handler) {
628 		pr_info("Spurious interrupt HPET channel %d\n", hc->num);
629 		return IRQ_HANDLED;
630 	}
631 
632 	evt->event_handler(evt);
633 	return IRQ_HANDLED;
634 }
635 
636 static int hpet_setup_msi_irq(struct hpet_channel *hc)
637 {
638 	if (request_irq(hc->irq, hpet_msi_interrupt_handler,
639 			IRQF_TIMER | IRQF_NOBALANCING,
640 			hc->name, hc))
641 		return -1;
642 
643 	disable_irq(hc->irq);
644 	irq_set_affinity(hc->irq, cpumask_of(hc->cpu));
645 	enable_irq(hc->irq);
646 
647 	pr_debug("%s irq %u for MSI\n", hc->name, hc->irq);
648 
649 	return 0;
650 }
651 
652 /* Invoked from the hotplug callback on @cpu */
653 static void init_one_hpet_msi_clockevent(struct hpet_channel *hc, int cpu)
654 {
655 	struct clock_event_device *evt = &hc->evt;
656 
657 	hc->cpu = cpu;
658 	per_cpu(cpu_hpet_channel, cpu) = hc;
659 	hpet_setup_msi_irq(hc);
660 
661 	hpet_init_clockevent(hc, 110);
662 	evt->tick_resume = hpet_clkevt_msi_resume;
663 
664 	clockevents_config_and_register(evt, hpet_freq, HPET_MIN_PROG_DELTA,
665 					0x7FFFFFFF);
666 }
667 
668 static struct hpet_channel *hpet_get_unused_clockevent(void)
669 {
670 	int i;
671 
672 	for (i = 0; i < hpet_base.nr_channels; i++) {
673 		struct hpet_channel *hc = hpet_base.channels + i;
674 
675 		if (hc->mode != HPET_MODE_CLOCKEVT || hc->in_use)
676 			continue;
677 		hc->in_use = 1;
678 		return hc;
679 	}
680 	return NULL;
681 }
682 
683 static int hpet_cpuhp_online(unsigned int cpu)
684 {
685 	struct hpet_channel *hc = hpet_get_unused_clockevent();
686 
687 	if (hc)
688 		init_one_hpet_msi_clockevent(hc, cpu);
689 	return 0;
690 }
691 
692 static int hpet_cpuhp_dead(unsigned int cpu)
693 {
694 	struct hpet_channel *hc = per_cpu(cpu_hpet_channel, cpu);
695 
696 	if (!hc)
697 		return 0;
698 	free_irq(hc->irq, hc);
699 	hc->in_use = 0;
700 	per_cpu(cpu_hpet_channel, cpu) = NULL;
701 	return 0;
702 }
703 
704 static void __init hpet_select_clockevents(void)
705 {
706 	unsigned int i;
707 
708 	hpet_base.nr_clockevents = 0;
709 
710 	/* No point if MSI is disabled or CPU has an Always Runing APIC Timer */
711 	if (hpet_msi_disable || boot_cpu_has(X86_FEATURE_ARAT))
712 		return;
713 
714 	hpet_print_config();
715 
716 	hpet_domain = hpet_create_irq_domain(hpet_blockid);
717 	if (!hpet_domain)
718 		return;
719 
720 	for (i = 0; i < hpet_base.nr_channels; i++) {
721 		struct hpet_channel *hc = hpet_base.channels + i;
722 		int irq;
723 
724 		if (hc->mode != HPET_MODE_UNUSED)
725 			continue;
726 
727 		/* Only consider HPET channel with MSI support */
728 		if (!(hc->boot_cfg & HPET_TN_FSB_CAP))
729 			continue;
730 
731 		sprintf(hc->name, "hpet%d", i);
732 
733 		irq = hpet_assign_irq(hpet_domain, hc, hc->num);
734 		if (irq <= 0)
735 			continue;
736 
737 		hc->irq = irq;
738 		hc->mode = HPET_MODE_CLOCKEVT;
739 
740 		if (++hpet_base.nr_clockevents == num_possible_cpus())
741 			break;
742 	}
743 
744 	pr_info("%d channels of %d reserved for per-cpu timers\n",
745 		hpet_base.nr_channels, hpet_base.nr_clockevents);
746 }
747 
748 #else
749 
750 static inline void hpet_select_clockevents(void) { }
751 
752 #define hpet_cpuhp_online	NULL
753 #define hpet_cpuhp_dead		NULL
754 
755 #endif
756 
757 /*
758  * Clock source related code
759  */
760 #if defined(CONFIG_SMP) && defined(CONFIG_64BIT)
761 /*
762  * Reading the HPET counter is a very slow operation. If a large number of
763  * CPUs are trying to access the HPET counter simultaneously, it can cause
764  * massive delays and slow down system performance dramatically. This may
765  * happen when HPET is the default clock source instead of TSC. For a
766  * really large system with hundreds of CPUs, the slowdown may be so
767  * severe, that it can actually crash the system because of a NMI watchdog
768  * soft lockup, for example.
769  *
770  * If multiple CPUs are trying to access the HPET counter at the same time,
771  * we don't actually need to read the counter multiple times. Instead, the
772  * other CPUs can use the counter value read by the first CPU in the group.
773  *
774  * This special feature is only enabled on x86-64 systems. It is unlikely
775  * that 32-bit x86 systems will have enough CPUs to require this feature
776  * with its associated locking overhead. We also need 64-bit atomic read.
777  *
778  * The lock and the HPET value are stored together and can be read in a
779  * single atomic 64-bit read. It is explicitly assumed that arch_spinlock_t
780  * is 32 bits in size.
781  */
782 union hpet_lock {
783 	struct {
784 		arch_spinlock_t lock;
785 		u32 value;
786 	};
787 	u64 lockval;
788 };
789 
790 static union hpet_lock hpet __cacheline_aligned = {
791 	{ .lock = __ARCH_SPIN_LOCK_UNLOCKED, },
792 };
793 
794 static u64 read_hpet(struct clocksource *cs)
795 {
796 	unsigned long flags;
797 	union hpet_lock old, new;
798 
799 	BUILD_BUG_ON(sizeof(union hpet_lock) != 8);
800 
801 	/*
802 	 * Read HPET directly if in NMI.
803 	 */
804 	if (in_nmi())
805 		return (u64)hpet_readl(HPET_COUNTER);
806 
807 	/*
808 	 * Read the current state of the lock and HPET value atomically.
809 	 */
810 	old.lockval = READ_ONCE(hpet.lockval);
811 
812 	if (arch_spin_is_locked(&old.lock))
813 		goto contended;
814 
815 	local_irq_save(flags);
816 	if (arch_spin_trylock(&hpet.lock)) {
817 		new.value = hpet_readl(HPET_COUNTER);
818 		/*
819 		 * Use WRITE_ONCE() to prevent store tearing.
820 		 */
821 		WRITE_ONCE(hpet.value, new.value);
822 		arch_spin_unlock(&hpet.lock);
823 		local_irq_restore(flags);
824 		return (u64)new.value;
825 	}
826 	local_irq_restore(flags);
827 
828 contended:
829 	/*
830 	 * Contended case
831 	 * --------------
832 	 * Wait until the HPET value change or the lock is free to indicate
833 	 * its value is up-to-date.
834 	 *
835 	 * It is possible that old.value has already contained the latest
836 	 * HPET value while the lock holder was in the process of releasing
837 	 * the lock. Checking for lock state change will enable us to return
838 	 * the value immediately instead of waiting for the next HPET reader
839 	 * to come along.
840 	 */
841 	do {
842 		cpu_relax();
843 		new.lockval = READ_ONCE(hpet.lockval);
844 	} while ((new.value == old.value) && arch_spin_is_locked(&new.lock));
845 
846 	return (u64)new.value;
847 }
848 #else
849 /*
850  * For UP or 32-bit.
851  */
852 static u64 read_hpet(struct clocksource *cs)
853 {
854 	return (u64)hpet_readl(HPET_COUNTER);
855 }
856 #endif
857 
858 static struct clocksource clocksource_hpet = {
859 	.name		= "hpet",
860 	.rating		= 250,
861 	.read		= read_hpet,
862 	.mask		= HPET_MASK,
863 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
864 	.resume		= hpet_resume_counter,
865 };
866 
867 /*
868  * AMD SB700 based systems with spread spectrum enabled use a SMM based
869  * HPET emulation to provide proper frequency setting.
870  *
871  * On such systems the SMM code is initialized with the first HPET register
872  * access and takes some time to complete. During this time the config
873  * register reads 0xffffffff. We check for max 1000 loops whether the
874  * config register reads a non-0xffffffff value to make sure that the
875  * HPET is up and running before we proceed any further.
876  *
877  * A counting loop is safe, as the HPET access takes thousands of CPU cycles.
878  *
879  * On non-SB700 based machines this check is only done once and has no
880  * side effects.
881  */
882 static bool __init hpet_cfg_working(void)
883 {
884 	int i;
885 
886 	for (i = 0; i < 1000; i++) {
887 		if (hpet_readl(HPET_CFG) != 0xFFFFFFFF)
888 			return true;
889 	}
890 
891 	pr_warn("Config register invalid. Disabling HPET\n");
892 	return false;
893 }
894 
895 static bool __init hpet_counting(void)
896 {
897 	u64 start, now, t1;
898 
899 	hpet_restart_counter();
900 
901 	t1 = hpet_readl(HPET_COUNTER);
902 	start = rdtsc();
903 
904 	/*
905 	 * We don't know the TSC frequency yet, but waiting for
906 	 * 200000 TSC cycles is safe:
907 	 * 4 GHz == 50us
908 	 * 1 GHz == 200us
909 	 */
910 	do {
911 		if (t1 != hpet_readl(HPET_COUNTER))
912 			return true;
913 		now = rdtsc();
914 	} while ((now - start) < 200000UL);
915 
916 	pr_warn("Counter not counting. HPET disabled\n");
917 	return false;
918 }
919 
920 static bool __init mwait_pc10_supported(void)
921 {
922 	unsigned int eax, ebx, ecx, mwait_substates;
923 
924 	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
925 		return false;
926 
927 	if (!cpu_feature_enabled(X86_FEATURE_MWAIT))
928 		return false;
929 
930 	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
931 		return false;
932 
933 	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
934 
935 	return (ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) &&
936 	       (ecx & CPUID5_ECX_INTERRUPT_BREAK) &&
937 	       (mwait_substates & (0xF << 28));
938 }
939 
940 /*
941  * Check whether the system supports PC10. If so force disable HPET as that
942  * stops counting in PC10. This check is overbroad as it does not take any
943  * of the following into account:
944  *
945  *	- ACPI tables
946  *	- Enablement of intel_idle
947  *	- Command line arguments which limit intel_idle C-state support
948  *
949  * That's perfectly fine. HPET is a piece of hardware designed by committee
950  * and the only reasons why it is still in use on modern systems is the
951  * fact that it is impossible to reliably query TSC and CPU frequency via
952  * CPUID or firmware.
953  *
954  * If HPET is functional it is useful for calibrating TSC, but this can be
955  * done via PMTIMER as well which seems to be the last remaining timer on
956  * X86/INTEL platforms that has not been completely wreckaged by feature
957  * creep.
958  *
959  * In theory HPET support should be removed altogether, but there are older
960  * systems out there which depend on it because TSC and APIC timer are
961  * dysfunctional in deeper C-states.
962  *
963  * It's only 20 years now that hardware people have been asked to provide
964  * reliable and discoverable facilities which can be used for timekeeping
965  * and per CPU timer interrupts.
966  *
967  * The probability that this problem is going to be solved in the
968  * forseeable future is close to zero, so the kernel has to be cluttered
969  * with heuristics to keep up with the ever growing amount of hardware and
970  * firmware trainwrecks. Hopefully some day hardware people will understand
971  * that the approach of "This can be fixed in software" is not sustainable.
972  * Hope dies last...
973  */
974 static bool __init hpet_is_pc10_damaged(void)
975 {
976 	unsigned long long pcfg;
977 
978 	/* Check whether PC10 substates are supported */
979 	if (!mwait_pc10_supported())
980 		return false;
981 
982 	/* Check whether PC10 is enabled in PKG C-state limit */
983 	rdmsrl(MSR_PKG_CST_CONFIG_CONTROL, pcfg);
984 	if ((pcfg & 0xF) < 8)
985 		return false;
986 
987 	if (hpet_force_user) {
988 		pr_warn("HPET force enabled via command line, but dysfunctional in PC10.\n");
989 		return false;
990 	}
991 
992 	pr_info("HPET dysfunctional in PC10. Force disabled.\n");
993 	boot_hpet_disable = true;
994 	return true;
995 }
996 
997 /**
998  * hpet_enable - Try to setup the HPET timer. Returns 1 on success.
999  */
1000 int __init hpet_enable(void)
1001 {
1002 	u32 hpet_period, cfg, id, irq;
1003 	unsigned int i, channels;
1004 	struct hpet_channel *hc;
1005 	u64 freq;
1006 
1007 	if (!is_hpet_capable())
1008 		return 0;
1009 
1010 	if (hpet_is_pc10_damaged())
1011 		return 0;
1012 
1013 	hpet_set_mapping();
1014 	if (!hpet_virt_address)
1015 		return 0;
1016 
1017 	/* Validate that the config register is working */
1018 	if (!hpet_cfg_working())
1019 		goto out_nohpet;
1020 
1021 	/*
1022 	 * Read the period and check for a sane value:
1023 	 */
1024 	hpet_period = hpet_readl(HPET_PERIOD);
1025 	if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
1026 		goto out_nohpet;
1027 
1028 	/* The period is a femtoseconds value. Convert it to a frequency. */
1029 	freq = FSEC_PER_SEC;
1030 	do_div(freq, hpet_period);
1031 	hpet_freq = freq;
1032 
1033 	/*
1034 	 * Read the HPET ID register to retrieve the IRQ routing
1035 	 * information and the number of channels
1036 	 */
1037 	id = hpet_readl(HPET_ID);
1038 	hpet_print_config();
1039 
1040 	/* This is the HPET channel number which is zero based */
1041 	channels = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
1042 
1043 	/*
1044 	 * The legacy routing mode needs at least two channels, tick timer
1045 	 * and the rtc emulation channel.
1046 	 */
1047 	if (IS_ENABLED(CONFIG_HPET_EMULATE_RTC) && channels < 2)
1048 		goto out_nohpet;
1049 
1050 	hc = kcalloc(channels, sizeof(*hc), GFP_KERNEL);
1051 	if (!hc) {
1052 		pr_warn("Disabling HPET.\n");
1053 		goto out_nohpet;
1054 	}
1055 	hpet_base.channels = hc;
1056 	hpet_base.nr_channels = channels;
1057 
1058 	/* Read, store and sanitize the global configuration */
1059 	cfg = hpet_readl(HPET_CFG);
1060 	hpet_base.boot_cfg = cfg;
1061 	cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY);
1062 	hpet_writel(cfg, HPET_CFG);
1063 	if (cfg)
1064 		pr_warn("Global config: Unknown bits %#x\n", cfg);
1065 
1066 	/* Read, store and sanitize the per channel configuration */
1067 	for (i = 0; i < channels; i++, hc++) {
1068 		hc->num = i;
1069 
1070 		cfg = hpet_readl(HPET_Tn_CFG(i));
1071 		hc->boot_cfg = cfg;
1072 		irq = (cfg & Tn_INT_ROUTE_CNF_MASK) >> Tn_INT_ROUTE_CNF_SHIFT;
1073 		hc->irq = irq;
1074 
1075 		cfg &= ~(HPET_TN_ENABLE | HPET_TN_LEVEL | HPET_TN_FSB);
1076 		hpet_writel(cfg, HPET_Tn_CFG(i));
1077 
1078 		cfg &= ~(HPET_TN_PERIODIC | HPET_TN_PERIODIC_CAP
1079 			 | HPET_TN_64BIT_CAP | HPET_TN_32BIT | HPET_TN_ROUTE
1080 			 | HPET_TN_FSB | HPET_TN_FSB_CAP);
1081 		if (cfg)
1082 			pr_warn("Channel #%u config: Unknown bits %#x\n", i, cfg);
1083 	}
1084 	hpet_print_config();
1085 
1086 	/*
1087 	 * Validate that the counter is counting. This needs to be done
1088 	 * after sanitizing the config registers to properly deal with
1089 	 * force enabled HPETs.
1090 	 */
1091 	if (!hpet_counting())
1092 		goto out_nohpet;
1093 
1094 	clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);
1095 
1096 	if (id & HPET_ID_LEGSUP) {
1097 		hpet_legacy_clockevent_register(&hpet_base.channels[0]);
1098 		hpet_base.channels[0].mode = HPET_MODE_LEGACY;
1099 		if (IS_ENABLED(CONFIG_HPET_EMULATE_RTC))
1100 			hpet_base.channels[1].mode = HPET_MODE_LEGACY;
1101 		return 1;
1102 	}
1103 	return 0;
1104 
1105 out_nohpet:
1106 	kfree(hpet_base.channels);
1107 	hpet_base.channels = NULL;
1108 	hpet_base.nr_channels = 0;
1109 	hpet_clear_mapping();
1110 	hpet_address = 0;
1111 	return 0;
1112 }
1113 
1114 /*
1115  * The late initialization runs after the PCI quirks have been invoked
1116  * which might have detected a system on which the HPET can be enforced.
1117  *
1118  * Also, the MSI machinery is not working yet when the HPET is initialized
1119  * early.
1120  *
1121  * If the HPET is enabled, then:
1122  *
1123  *  1) Reserve one channel for /dev/hpet if CONFIG_HPET=y
1124  *  2) Reserve up to num_possible_cpus() channels as per CPU clockevents
1125  *  3) Setup /dev/hpet if CONFIG_HPET=y
1126  *  4) Register hotplug callbacks when clockevents are available
1127  */
1128 static __init int hpet_late_init(void)
1129 {
1130 	int ret;
1131 
1132 	if (!hpet_address) {
1133 		if (!force_hpet_address)
1134 			return -ENODEV;
1135 
1136 		hpet_address = force_hpet_address;
1137 		hpet_enable();
1138 	}
1139 
1140 	if (!hpet_virt_address)
1141 		return -ENODEV;
1142 
1143 	hpet_select_device_channel();
1144 	hpet_select_clockevents();
1145 	hpet_reserve_platform_timers();
1146 	hpet_print_config();
1147 
1148 	if (!hpet_base.nr_clockevents)
1149 		return 0;
1150 
1151 	ret = cpuhp_setup_state(CPUHP_AP_X86_HPET_ONLINE, "x86/hpet:online",
1152 				hpet_cpuhp_online, NULL);
1153 	if (ret)
1154 		return ret;
1155 	ret = cpuhp_setup_state(CPUHP_X86_HPET_DEAD, "x86/hpet:dead", NULL,
1156 				hpet_cpuhp_dead);
1157 	if (ret)
1158 		goto err_cpuhp;
1159 	return 0;
1160 
1161 err_cpuhp:
1162 	cpuhp_remove_state(CPUHP_AP_X86_HPET_ONLINE);
1163 	return ret;
1164 }
1165 fs_initcall(hpet_late_init);
1166 
1167 void hpet_disable(void)
1168 {
1169 	unsigned int i;
1170 	u32 cfg;
1171 
1172 	if (!is_hpet_capable() || !hpet_virt_address)
1173 		return;
1174 
1175 	/* Restore boot configuration with the enable bit cleared */
1176 	cfg = hpet_base.boot_cfg;
1177 	cfg &= ~HPET_CFG_ENABLE;
1178 	hpet_writel(cfg, HPET_CFG);
1179 
1180 	/* Restore the channel boot configuration */
1181 	for (i = 0; i < hpet_base.nr_channels; i++)
1182 		hpet_writel(hpet_base.channels[i].boot_cfg, HPET_Tn_CFG(i));
1183 
1184 	/* If the HPET was enabled at boot time, reenable it */
1185 	if (hpet_base.boot_cfg & HPET_CFG_ENABLE)
1186 		hpet_writel(hpet_base.boot_cfg, HPET_CFG);
1187 }
1188 
1189 #ifdef CONFIG_HPET_EMULATE_RTC
1190 
1191 /*
1192  * HPET in LegacyReplacement mode eats up the RTC interrupt line. When HPET
1193  * is enabled, we support RTC interrupt functionality in software.
1194  *
1195  * RTC has 3 kinds of interrupts:
1196  *
1197  *  1) Update Interrupt - generate an interrupt, every second, when the
1198  *     RTC clock is updated
1199  *  2) Alarm Interrupt - generate an interrupt at a specific time of day
1200  *  3) Periodic Interrupt - generate periodic interrupt, with frequencies
1201  *     2Hz-8192Hz (2Hz-64Hz for non-root user) (all frequencies in powers of 2)
1202  *
1203  * (1) and (2) above are implemented using polling at a frequency of 64 Hz:
1204  * DEFAULT_RTC_INT_FREQ.
1205  *
1206  * The exact frequency is a tradeoff between accuracy and interrupt overhead.
1207  *
1208  * For (3), we use interrupts at 64 Hz, or the user specified periodic frequency,
1209  * if it's higher.
1210  */
1211 #include <linux/mc146818rtc.h>
1212 #include <linux/rtc.h>
1213 
1214 #define DEFAULT_RTC_INT_FREQ	64
1215 #define DEFAULT_RTC_SHIFT	6
1216 #define RTC_NUM_INTS		1
1217 
1218 static unsigned long hpet_rtc_flags;
1219 static int hpet_prev_update_sec;
1220 static struct rtc_time hpet_alarm_time;
1221 static unsigned long hpet_pie_count;
1222 static u32 hpet_t1_cmp;
1223 static u32 hpet_default_delta;
1224 static u32 hpet_pie_delta;
1225 static unsigned long hpet_pie_limit;
1226 
1227 static rtc_irq_handler irq_handler;
1228 
1229 /*
1230  * Check that the HPET counter c1 is ahead of c2
1231  */
1232 static inline int hpet_cnt_ahead(u32 c1, u32 c2)
1233 {
1234 	return (s32)(c2 - c1) < 0;
1235 }
1236 
1237 /*
1238  * Registers a IRQ handler.
1239  */
1240 int hpet_register_irq_handler(rtc_irq_handler handler)
1241 {
1242 	if (!is_hpet_enabled())
1243 		return -ENODEV;
1244 	if (irq_handler)
1245 		return -EBUSY;
1246 
1247 	irq_handler = handler;
1248 
1249 	return 0;
1250 }
1251 EXPORT_SYMBOL_GPL(hpet_register_irq_handler);
1252 
1253 /*
1254  * Deregisters the IRQ handler registered with hpet_register_irq_handler()
1255  * and does cleanup.
1256  */
1257 void hpet_unregister_irq_handler(rtc_irq_handler handler)
1258 {
1259 	if (!is_hpet_enabled())
1260 		return;
1261 
1262 	irq_handler = NULL;
1263 	hpet_rtc_flags = 0;
1264 }
1265 EXPORT_SYMBOL_GPL(hpet_unregister_irq_handler);
1266 
1267 /*
1268  * Channel 1 for RTC emulation. We use one shot mode, as periodic mode
1269  * is not supported by all HPET implementations for channel 1.
1270  *
1271  * hpet_rtc_timer_init() is called when the rtc is initialized.
1272  */
1273 int hpet_rtc_timer_init(void)
1274 {
1275 	unsigned int cfg, cnt, delta;
1276 	unsigned long flags;
1277 
1278 	if (!is_hpet_enabled())
1279 		return 0;
1280 
1281 	if (!hpet_default_delta) {
1282 		struct clock_event_device *evt = &hpet_base.channels[0].evt;
1283 		uint64_t clc;
1284 
1285 		clc = (uint64_t) evt->mult * NSEC_PER_SEC;
1286 		clc >>= evt->shift + DEFAULT_RTC_SHIFT;
1287 		hpet_default_delta = clc;
1288 	}
1289 
1290 	if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
1291 		delta = hpet_default_delta;
1292 	else
1293 		delta = hpet_pie_delta;
1294 
1295 	local_irq_save(flags);
1296 
1297 	cnt = delta + hpet_readl(HPET_COUNTER);
1298 	hpet_writel(cnt, HPET_T1_CMP);
1299 	hpet_t1_cmp = cnt;
1300 
1301 	cfg = hpet_readl(HPET_T1_CFG);
1302 	cfg &= ~HPET_TN_PERIODIC;
1303 	cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
1304 	hpet_writel(cfg, HPET_T1_CFG);
1305 
1306 	local_irq_restore(flags);
1307 
1308 	return 1;
1309 }
1310 EXPORT_SYMBOL_GPL(hpet_rtc_timer_init);
1311 
1312 static void hpet_disable_rtc_channel(void)
1313 {
1314 	u32 cfg = hpet_readl(HPET_T1_CFG);
1315 
1316 	cfg &= ~HPET_TN_ENABLE;
1317 	hpet_writel(cfg, HPET_T1_CFG);
1318 }
1319 
1320 /*
1321  * The functions below are called from rtc driver.
1322  * Return 0 if HPET is not being used.
1323  * Otherwise do the necessary changes and return 1.
1324  */
1325 int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
1326 {
1327 	if (!is_hpet_enabled())
1328 		return 0;
1329 
1330 	hpet_rtc_flags &= ~bit_mask;
1331 	if (unlikely(!hpet_rtc_flags))
1332 		hpet_disable_rtc_channel();
1333 
1334 	return 1;
1335 }
1336 EXPORT_SYMBOL_GPL(hpet_mask_rtc_irq_bit);
1337 
1338 int hpet_set_rtc_irq_bit(unsigned long bit_mask)
1339 {
1340 	unsigned long oldbits = hpet_rtc_flags;
1341 
1342 	if (!is_hpet_enabled())
1343 		return 0;
1344 
1345 	hpet_rtc_flags |= bit_mask;
1346 
1347 	if ((bit_mask & RTC_UIE) && !(oldbits & RTC_UIE))
1348 		hpet_prev_update_sec = -1;
1349 
1350 	if (!oldbits)
1351 		hpet_rtc_timer_init();
1352 
1353 	return 1;
1354 }
1355 EXPORT_SYMBOL_GPL(hpet_set_rtc_irq_bit);
1356 
1357 int hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
1358 {
1359 	if (!is_hpet_enabled())
1360 		return 0;
1361 
1362 	hpet_alarm_time.tm_hour = hrs;
1363 	hpet_alarm_time.tm_min = min;
1364 	hpet_alarm_time.tm_sec = sec;
1365 
1366 	return 1;
1367 }
1368 EXPORT_SYMBOL_GPL(hpet_set_alarm_time);
1369 
1370 int hpet_set_periodic_freq(unsigned long freq)
1371 {
1372 	uint64_t clc;
1373 
1374 	if (!is_hpet_enabled())
1375 		return 0;
1376 
1377 	if (freq <= DEFAULT_RTC_INT_FREQ) {
1378 		hpet_pie_limit = DEFAULT_RTC_INT_FREQ / freq;
1379 	} else {
1380 		struct clock_event_device *evt = &hpet_base.channels[0].evt;
1381 
1382 		clc = (uint64_t) evt->mult * NSEC_PER_SEC;
1383 		do_div(clc, freq);
1384 		clc >>= evt->shift;
1385 		hpet_pie_delta = clc;
1386 		hpet_pie_limit = 0;
1387 	}
1388 
1389 	return 1;
1390 }
1391 EXPORT_SYMBOL_GPL(hpet_set_periodic_freq);
1392 
1393 int hpet_rtc_dropped_irq(void)
1394 {
1395 	return is_hpet_enabled();
1396 }
1397 EXPORT_SYMBOL_GPL(hpet_rtc_dropped_irq);
1398 
1399 static void hpet_rtc_timer_reinit(void)
1400 {
1401 	unsigned int delta;
1402 	int lost_ints = -1;
1403 
1404 	if (unlikely(!hpet_rtc_flags))
1405 		hpet_disable_rtc_channel();
1406 
1407 	if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
1408 		delta = hpet_default_delta;
1409 	else
1410 		delta = hpet_pie_delta;
1411 
1412 	/*
1413 	 * Increment the comparator value until we are ahead of the
1414 	 * current count.
1415 	 */
1416 	do {
1417 		hpet_t1_cmp += delta;
1418 		hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
1419 		lost_ints++;
1420 	} while (!hpet_cnt_ahead(hpet_t1_cmp, hpet_readl(HPET_COUNTER)));
1421 
1422 	if (lost_ints) {
1423 		if (hpet_rtc_flags & RTC_PIE)
1424 			hpet_pie_count += lost_ints;
1425 		if (printk_ratelimit())
1426 			pr_warn("Lost %d RTC interrupts\n", lost_ints);
1427 	}
1428 }
1429 
1430 irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
1431 {
1432 	struct rtc_time curr_time;
1433 	unsigned long rtc_int_flag = 0;
1434 
1435 	hpet_rtc_timer_reinit();
1436 	memset(&curr_time, 0, sizeof(struct rtc_time));
1437 
1438 	if (hpet_rtc_flags & (RTC_UIE | RTC_AIE)) {
1439 		if (unlikely(mc146818_get_time(&curr_time) < 0)) {
1440 			pr_err_ratelimited("unable to read current time from RTC\n");
1441 			return IRQ_HANDLED;
1442 		}
1443 	}
1444 
1445 	if (hpet_rtc_flags & RTC_UIE &&
1446 	    curr_time.tm_sec != hpet_prev_update_sec) {
1447 		if (hpet_prev_update_sec >= 0)
1448 			rtc_int_flag = RTC_UF;
1449 		hpet_prev_update_sec = curr_time.tm_sec;
1450 	}
1451 
1452 	if (hpet_rtc_flags & RTC_PIE && ++hpet_pie_count >= hpet_pie_limit) {
1453 		rtc_int_flag |= RTC_PF;
1454 		hpet_pie_count = 0;
1455 	}
1456 
1457 	if (hpet_rtc_flags & RTC_AIE &&
1458 	    (curr_time.tm_sec == hpet_alarm_time.tm_sec) &&
1459 	    (curr_time.tm_min == hpet_alarm_time.tm_min) &&
1460 	    (curr_time.tm_hour == hpet_alarm_time.tm_hour))
1461 		rtc_int_flag |= RTC_AF;
1462 
1463 	if (rtc_int_flag) {
1464 		rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
1465 		if (irq_handler)
1466 			irq_handler(rtc_int_flag, dev_id);
1467 	}
1468 	return IRQ_HANDLED;
1469 }
1470 EXPORT_SYMBOL_GPL(hpet_rtc_interrupt);
1471 #endif
1472