1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * SGI RTC clock/timer routines.
4 *
5 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
6 * Copyright (c) 2009-2013 Silicon Graphics, Inc. All Rights Reserved.
7 * Copyright (c) Dimitri Sivanich
8 */
9#include <linux/clockchips.h>
10#include <linux/slab.h>
11
12#include <asm/uv/uv_mmrs.h>
13#include <asm/uv/uv_hub.h>
14#include <asm/uv/bios.h>
15#include <asm/uv/uv.h>
16#include <asm/apic.h>
17#include <asm/cpu.h>
18
19#define RTC_NAME "sgi_rtc"
20
21static u64 uv_read_rtc(struct clocksource *cs);
22static int uv_rtc_next_event(unsigned long, struct clock_event_device *);
23static int uv_rtc_shutdown(struct clock_event_device *evt);
24
25static struct clocksource clocksource_uv = {
26 .name = RTC_NAME,
27 .rating = 299,
28 .read = uv_read_rtc,
29 .mask = (u64)UVH_RTC_REAL_TIME_CLOCK_MASK,
30 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
31};
32
33static struct clock_event_device clock_event_device_uv = {
34 .name = RTC_NAME,
35 .features = CLOCK_EVT_FEAT_ONESHOT,
36 .shift = 20,
37 .rating = 400,
38 .irq = -1,
39 .set_next_event = uv_rtc_next_event,
40 .set_state_shutdown = uv_rtc_shutdown,
41 .event_handler = NULL,
42};
43
44static DEFINE_PER_CPU(struct clock_event_device, cpu_ced);
45
46/* There is one of these allocated per node */
47struct uv_rtc_timer_head {
48 spinlock_t lock;
49 /* next cpu waiting for timer, local node relative: */
50 int next_cpu;
51 /* number of cpus on this node: */
52 int ncpus;
53 struct {
54 int lcpu; /* systemwide logical cpu number */
55 u64 expires; /* next timer expiration for this cpu */
56 } cpu[] __counted_by(ncpus);
57};
58
59/*
60 * Access to uv_rtc_timer_head via blade id.
61 */
62static struct uv_rtc_timer_head **blade_info __read_mostly;
63
64static int uv_rtc_evt_enable;
65
66/*
67 * Hardware interface routines
68 */
69
70/* Send IPIs to another node */
71static void uv_rtc_send_IPI(int cpu)
72{
73 unsigned long apicid, val;
74 int pnode;
75
76 apicid = cpu_physical_id(cpu);
77 pnode = uv_apicid_to_pnode(apicid);
78 val = (1UL << UVH_IPI_INT_SEND_SHFT) |
79 (apicid << UVH_IPI_INT_APIC_ID_SHFT) |
80 (X86_PLATFORM_IPI_VECTOR << UVH_IPI_INT_VECTOR_SHFT);
81
82 uv_write_global_mmr64(pnode, UVH_IPI_INT, val);
83}
84
85/* Check for an RTC interrupt pending */
86static int uv_intr_pending(int pnode)
87{
88 return uv_read_global_mmr64(pnode, UVH_EVENT_OCCURRED2) &
89 UVH_EVENT_OCCURRED2_RTC_1_MASK;
90}
91
92/* Setup interrupt and return non-zero if early expiration occurred. */
93static int uv_setup_intr(int cpu, u64 expires)
94{
95 u64 val;
96 unsigned long apicid = cpu_physical_id(cpu);
97 int pnode = uv_cpu_to_pnode(cpu);
98
99 uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
100 UVH_RTC1_INT_CONFIG_M_MASK);
101 uv_write_global_mmr64(pnode, UVH_INT_CMPB, val: -1L);
102
103 uv_write_global_mmr64(pnode, UVH_EVENT_OCCURRED2_ALIAS,
104 UVH_EVENT_OCCURRED2_RTC_1_MASK);
105
106 val = (X86_PLATFORM_IPI_VECTOR << UVH_RTC1_INT_CONFIG_VECTOR_SHFT) |
107 ((u64)apicid << UVH_RTC1_INT_CONFIG_APIC_ID_SHFT);
108
109 /* Set configuration */
110 uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG, val);
111 /* Initialize comparator value */
112 uv_write_global_mmr64(pnode, UVH_INT_CMPB, val: expires);
113
114 if (uv_read_rtc(NULL) <= expires)
115 return 0;
116
117 return !uv_intr_pending(pnode);
118}
119
120/*
121 * Per-cpu timer tracking routines
122 */
123
124static __init void uv_rtc_deallocate_timers(void)
125{
126 int bid;
127
128 for_each_possible_blade(bid) {
129 kfree(objp: blade_info[bid]);
130 }
131 kfree(objp: blade_info);
132}
133
134/* Allocate per-node list of cpu timer expiration times. */
135static __init int uv_rtc_allocate_timers(void)
136{
137 int cpu;
138
139 blade_info = kcalloc(uv_possible_blades, sizeof(void *), GFP_KERNEL);
140 if (!blade_info)
141 return -ENOMEM;
142
143 for_each_present_cpu(cpu) {
144 int nid = cpu_to_node(cpu);
145 int bid = uv_cpu_to_blade_id(cpu);
146 int bcpu = uv_cpu_blade_processor_id(cpu);
147 struct uv_rtc_timer_head *head = blade_info[bid];
148
149 if (!head) {
150 head = kmalloc_node(struct_size(head, cpu,
151 uv_blade_nr_possible_cpus(bid)),
152 GFP_KERNEL, nid);
153 if (!head) {
154 uv_rtc_deallocate_timers();
155 return -ENOMEM;
156 }
157 spin_lock_init(&head->lock);
158 head->ncpus = uv_blade_nr_possible_cpus(bid);
159 head->next_cpu = -1;
160 blade_info[bid] = head;
161 }
162
163 head->cpu[bcpu].lcpu = cpu;
164 head->cpu[bcpu].expires = ULLONG_MAX;
165 }
166
167 return 0;
168}
169
170/* Find and set the next expiring timer. */
171static void uv_rtc_find_next_timer(struct uv_rtc_timer_head *head, int pnode)
172{
173 u64 lowest = ULLONG_MAX;
174 int c, bcpu = -1;
175
176 head->next_cpu = -1;
177 for (c = 0; c < head->ncpus; c++) {
178 u64 exp = head->cpu[c].expires;
179 if (exp < lowest) {
180 bcpu = c;
181 lowest = exp;
182 }
183 }
184 if (bcpu >= 0) {
185 head->next_cpu = bcpu;
186 c = head->cpu[bcpu].lcpu;
187 if (uv_setup_intr(cpu: c, expires: lowest))
188 /* If we didn't set it up in time, trigger */
189 uv_rtc_send_IPI(cpu: c);
190 } else {
191 uv_write_global_mmr64(pnode, UVH_RTC1_INT_CONFIG,
192 UVH_RTC1_INT_CONFIG_M_MASK);
193 }
194}
195
196/*
197 * Set expiration time for current cpu.
198 *
199 * Returns 1 if we missed the expiration time.
200 */
201static int uv_rtc_set_timer(int cpu, u64 expires)
202{
203 int pnode = uv_cpu_to_pnode(cpu);
204 int bid = uv_cpu_to_blade_id(cpu);
205 struct uv_rtc_timer_head *head = blade_info[bid];
206 int bcpu = uv_cpu_blade_processor_id(cpu);
207 u64 *t = &head->cpu[bcpu].expires;
208 unsigned long flags;
209 int next_cpu;
210
211 spin_lock_irqsave(&head->lock, flags);
212
213 next_cpu = head->next_cpu;
214 *t = expires;
215
216 /* Will this one be next to go off? */
217 if (next_cpu < 0 || bcpu == next_cpu ||
218 expires < head->cpu[next_cpu].expires) {
219 head->next_cpu = bcpu;
220 if (uv_setup_intr(cpu, expires)) {
221 *t = ULLONG_MAX;
222 uv_rtc_find_next_timer(head, pnode);
223 spin_unlock_irqrestore(lock: &head->lock, flags);
224 return -ETIME;
225 }
226 }
227
228 spin_unlock_irqrestore(lock: &head->lock, flags);
229 return 0;
230}
231
232/*
233 * Unset expiration time for current cpu.
234 *
235 * Returns 1 if this timer was pending.
236 */
237static int uv_rtc_unset_timer(int cpu, int force)
238{
239 int pnode = uv_cpu_to_pnode(cpu);
240 int bid = uv_cpu_to_blade_id(cpu);
241 struct uv_rtc_timer_head *head = blade_info[bid];
242 int bcpu = uv_cpu_blade_processor_id(cpu);
243 u64 *t = &head->cpu[bcpu].expires;
244 unsigned long flags;
245 int rc = 0;
246
247 spin_lock_irqsave(&head->lock, flags);
248
249 if ((head->next_cpu == bcpu && uv_read_rtc(NULL) >= *t) || force)
250 rc = 1;
251
252 if (rc) {
253 *t = ULLONG_MAX;
254 /* Was the hardware setup for this timer? */
255 if (head->next_cpu == bcpu)
256 uv_rtc_find_next_timer(head, pnode);
257 }
258
259 spin_unlock_irqrestore(lock: &head->lock, flags);
260
261 return rc;
262}
263
264
265/*
266 * Kernel interface routines.
267 */
268
269/*
270 * Read the RTC.
271 *
272 * Starting with HUB rev 2.0, the UV RTC register is replicated across all
273 * cachelines of its own page. This allows faster simultaneous reads
274 * from a given socket.
275 */
276static u64 uv_read_rtc(struct clocksource *cs)
277{
278 unsigned long offset;
279
280 if (uv_get_min_hub_revision_id() == 1)
281 offset = 0;
282 else
283 offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
284
285 return (u64)uv_read_local_mmr(UVH_RTC | offset);
286}
287
288/*
289 * Program the next event, relative to now
290 */
291static int uv_rtc_next_event(unsigned long delta,
292 struct clock_event_device *ced)
293{
294 int ced_cpu = cpumask_first(srcp: ced->cpumask);
295
296 return uv_rtc_set_timer(cpu: ced_cpu, expires: delta + uv_read_rtc(NULL));
297}
298
299/*
300 * Shutdown the RTC timer
301 */
302static int uv_rtc_shutdown(struct clock_event_device *evt)
303{
304 int ced_cpu = cpumask_first(srcp: evt->cpumask);
305
306 uv_rtc_unset_timer(cpu: ced_cpu, force: 1);
307 return 0;
308}
309
310static void uv_rtc_interrupt(void)
311{
312 int cpu = smp_processor_id();
313 struct clock_event_device *ced = &per_cpu(cpu_ced, cpu);
314
315 if (!ced || !ced->event_handler)
316 return;
317
318 if (uv_rtc_unset_timer(cpu, force: 0) != 1)
319 return;
320
321 ced->event_handler(ced);
322}
323
324static int __init uv_enable_evt_rtc(char *str)
325{
326 uv_rtc_evt_enable = 1;
327
328 return 1;
329}
330__setup("uvrtcevt", uv_enable_evt_rtc);
331
332static __init void uv_rtc_register_clockevents(struct work_struct *dummy)
333{
334 struct clock_event_device *ced = this_cpu_ptr(&cpu_ced);
335
336 *ced = clock_event_device_uv;
337 ced->cpumask = cpumask_of(smp_processor_id());
338 clockevents_register_device(dev: ced);
339}
340
341static __init int uv_rtc_setup_clock(void)
342{
343 int rc;
344
345 if (!is_uv_system())
346 return -ENODEV;
347
348 rc = clocksource_register_hz(cs: &clocksource_uv, hz: sn_rtc_cycles_per_second);
349 if (rc)
350 printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);
351 else
352 printk(KERN_INFO "UV RTC clocksource registered freq %lu MHz\n",
353 sn_rtc_cycles_per_second/(unsigned long)1E6);
354
355 if (rc || !uv_rtc_evt_enable || x86_platform_ipi_callback)
356 return rc;
357
358 /* Setup and register clockevents */
359 rc = uv_rtc_allocate_timers();
360 if (rc)
361 goto error;
362
363 x86_platform_ipi_callback = uv_rtc_interrupt;
364
365 clock_event_device_uv.mult = div_sc(ticks: sn_rtc_cycles_per_second,
366 NSEC_PER_SEC, shift: clock_event_device_uv.shift);
367
368 clock_event_device_uv.min_delta_ns = NSEC_PER_SEC /
369 sn_rtc_cycles_per_second;
370 clock_event_device_uv.min_delta_ticks = 1;
371
372 clock_event_device_uv.max_delta_ns = clocksource_uv.mask *
373 (NSEC_PER_SEC / sn_rtc_cycles_per_second);
374 clock_event_device_uv.max_delta_ticks = clocksource_uv.mask;
375
376 rc = schedule_on_each_cpu(func: uv_rtc_register_clockevents);
377 if (rc) {
378 x86_platform_ipi_callback = NULL;
379 uv_rtc_deallocate_timers();
380 goto error;
381 }
382
383 printk(KERN_INFO "UV RTC clockevents registered\n");
384
385 return 0;
386
387error:
388 clocksource_unregister(&clocksource_uv);
389 printk(KERN_INFO "UV RTC clockevents failed rc %d\n", rc);
390
391 return rc;
392}
393arch_initcall(uv_rtc_setup_clock);
394

source code of linux/arch/x86/platform/uv/uv_time.c