1 /*
2  *
3  * Copyright (C) 2015 Numascale AS. All rights reserved.
4  *
5  * This software is licensed under the terms of the GNU General Public
6  * License version 2, as published by the Free Software Foundation, and
7  * may be copied, distributed, and modified under those terms.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  */
15 
16 #include <linux/clockchips.h>
17 
18 #include <asm/irq.h>
19 #include <asm/numachip/numachip.h>
20 #include <asm/numachip/numachip_csr.h>
21 
22 static DEFINE_PER_CPU(struct clock_event_device, numachip2_ced);
23 
24 static cycles_t numachip2_timer_read(struct clocksource *cs)
25 {
26 	return numachip2_read64_lcsr(NUMACHIP2_TIMER_NOW);
27 }
28 
29 static struct clocksource numachip2_clocksource = {
30 	.name            = "numachip2",
31 	.rating          = 295,
32 	.read            = numachip2_timer_read,
33 	.mask            = CLOCKSOURCE_MASK(64),
34 	.flags           = CLOCK_SOURCE_IS_CONTINUOUS,
35 	.mult            = 1,
36 	.shift           = 0,
37 };
38 
39 static int numachip2_set_next_event(unsigned long delta, struct clock_event_device *ced)
40 {
41 	numachip2_write64_lcsr(NUMACHIP2_TIMER_DEADLINE + numachip2_timer(),
42 		delta);
43 	return 0;
44 }
45 
46 static struct clock_event_device numachip2_clockevent = {
47 	.name            = "numachip2",
48 	.rating          = 400,
49 	.set_next_event  = numachip2_set_next_event,
50 	.features        = CLOCK_EVT_FEAT_ONESHOT,
51 	.mult            = 1,
52 	.shift           = 0,
53 	.min_delta_ns    = 1250,
54 	.min_delta_ticks = 1250,
55 	.max_delta_ns    = LONG_MAX,
56 	.max_delta_ticks = LONG_MAX,
57 };
58 
59 static void numachip_timer_interrupt(void)
60 {
61 	struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
62 
63 	ced->event_handler(ced);
64 }
65 
66 static __init void numachip_timer_each(struct work_struct *work)
67 {
68 	unsigned local_apicid = __this_cpu_read(x86_cpu_to_apicid) & 0xff;
69 	struct clock_event_device *ced = this_cpu_ptr(&numachip2_ced);
70 
71 	/* Setup IPI vector to local core and relative timing mode */
72 	numachip2_write64_lcsr(NUMACHIP2_TIMER_INT + numachip2_timer(),
73 		(3 << 22) | (X86_PLATFORM_IPI_VECTOR << 14) |
74 		(local_apicid << 6));
75 
76 	*ced = numachip2_clockevent;
77 	ced->cpumask = cpumask_of(smp_processor_id());
78 	clockevents_register_device(ced);
79 }
80 
81 static int __init numachip_timer_init(void)
82 {
83 	if (numachip_system != 2)
84 		return -ENODEV;
85 
86 	/* Reset timer */
87 	numachip2_write64_lcsr(NUMACHIP2_TIMER_RESET, 0);
88 	clocksource_register_hz(&numachip2_clocksource, NSEC_PER_SEC);
89 
90 	/* Setup per-cpu clockevents */
91 	x86_platform_ipi_callback = numachip_timer_interrupt;
92 	schedule_on_each_cpu(&numachip_timer_each);
93 
94 	return 0;
95 }
96 
97 arch_initcall(numachip_timer_init);
98